@phdthesis{Cheng2024, author = {Cheng, Feng}, title = {Evolution and ontogeny of electric organ discharge in African weakly electric fish genus Campylomormyrus: a genomic and transcriptomic perspective}, doi = {10.25932/publishup-63017}, url = {http://nbn-resolving.de/urn:nbn:de:kobv:517-opus4-630172}, school = {Universit{\"a}t Potsdam}, pages = {176}, year = {2024}, abstract = {The African weakly electric fishes (Mormyridae) exhibit a remarkable adaptive radiation possibly due to their species-specific electric organ discharges (EODs). It is produced by a muscle-derived electric organ that is located in the caudal peduncle. Divergence in EODs acts as a pre-zygotic isolation mechanism to drive species radiations. However, the mechanism behind the EOD diversification are only partially understood. The aim of this study is to explore the genetic basis of EOD diversification from the gene expression level across Campylomormyrus species/hybrids and ontogeny. I firstly produced a high quality genome of the species C. compressirostris as a valuable resource to understand the electric fish evolution. The next study compared the gene expression pattern between electric organs and skeletal muscles in Campylomormyrus species/hybrids with different types of EOD duration. I identified several candidate genes with an electric organ-specific expression, e.g. KCNA7a, KLF5, KCNJ2, SCN4aa, NDRG3, MEF2. The overall genes expression pattern exhibited a significant association with EOD duration in all analyzed species/hybrids. The expression of several candidate genes, e.g. KCNJ2, KLF5, KCNK6 and KCNQ5, possibly contribute to the regulation of EOD duration in Campylomormyrus due to their increasing or decreasing expression. Several potassium channel genes showed differential expression during ontogeny in species and hybrid with EOD alteration, e.g. KCNJ2. I next explored allele specific expression of intragenus hybrids by crossing the duration EOD species C. compressirostris with the medium duration EOD species C. tshokwe and the elongated duration EOD species C. rhynchophorus. The hybrids exhibited global expression dominance of the C. compressirostris allele in the adult skeletal muscle and electric organ, as well as in the juvenile electric organ. Only the gene KCNJ2 showed dominant expression of the allele from C. rhynchophorus, and this was increasingly dominant during ontogeny. It hence supported our hypothesis that KCNJ2 is a key gene of regulating EOD duration. Our results help us to understand, from a genetic perspective, how gene expression effect the EOD diversification in the African weakly electric fish.}, language = {en} } @phdthesis{Kersting2024, author = {Kersting, Katerina}, title = {Development of a CRISPR/Cas gene editing technique for the coccolithophore Chrysotila carterae}, school = {Universit{\"a}t Potsdam}, pages = {137}, year = {2024}, language = {en} } @phdthesis{Stange2024, author = {Stange, Maike}, title = {A study on Coronin-A and Aip1 function in motility of Dictyostelium discoideum and on Aip1 interchangeability between Dictyostelium discoideum and Arabidopsis thaliana}, doi = {10.25932/publishup-62856}, url = {http://nbn-resolving.de/urn:nbn:de:kobv:517-opus4-628569}, school = {Universit{\"a}t Potsdam}, pages = {xiv, 168}, year = {2024}, abstract = {Actin is one of the most highly conserved proteins in eukaryotes and distinct actin-related proteins with filament-forming properties are even found in prokaryotes. Due to these commonalities, actin-modulating proteins of many species share similar structural properties and proposed functions. The polymerization and depolymerization of actin are critical processes for a cell as they can contribute to shape changes to adapt to its environment and to move and distribute nutrients and cellular components within the cell. However, to what extent functions of actin-binding proteins are conserved between distantly related species, has only been addressed in a few cases. In this work, functions of Coronin-A (CorA) and Actin-interacting protein 1 (Aip1), two proteins involved in actin dynamics, were characterized. In addition, the interchangeability and function of Aip1 were investigated in two phylogenetically distant model organisms. The flowering plant Arabidopsis thaliana (encoding two homologs, AIP1-1 and AIP1-2) and in the amoeba Dictyostelium discoideum (encoding one homolog, DdAip1) were chosen because the functions of their actin cytoskeletons may differ in many aspects. Functional analyses between species were conducted for AIP1 homologs as flowering plants do not harbor a CorA gene. In the first part of the study, the effect of four different mutation methods on the function of Coronin-A protein and the resulting phenotype in D. discoideum was revealed in two genetic knockouts, one RNAi knockdown and a sudden loss-of-function mutant created by chemical-induced dislocation (CID). The advantages and disadvantages of the different mutation methods on the motility, appearance and development of the amoebae were investigated, and the results showed that not all observed properties were affected with the same intensity. Remarkably, a new combination of Selection-Linked Integration and CID could be established. In the second and third parts of the thesis, the exchange of Aip1 between plant and amoeba was carried out. For A. thaliana, the two homologs (AIP1-1 and AIP1-2) were analyzed for functionality as well as in D. discoideum. In the Aip1-deficient amoeba, rescue with AIP1-1 was more effective than with AIP1-2. The main results in the plant showed that in the aip1-2 mutant background, reintroduced AIP1-2 displayed the most efficient rescue and A. thaliana AIP1-1 rescued better than DdAip1. The choice of the tagging site was important for the function of Aip1 as steric hindrance is a problem. The DdAip1 was less effective when tagged at the C-terminus, while the plant AIP1s showed mixed results depending on the tag position. In conclusion, the foreign proteins partially rescued phenotypes of mutant plants and mutant amoebae, despite the organisms only being very distantly related in evolutionary terms.}, language = {en} } @phdthesis{You2024, author = {You, Lili}, title = {Chloroplast engineering for recombinant protein production and stress protection}, school = {Universit{\"a}t Potsdam}, pages = {133}, year = {2024}, language = {en} } @phdthesis{Schaefer2024, author = {Sch{\"a}fer, Marj{\"a}nn Helena}, title = {Untersuchungen zur Evolution der 15-Lipoxygenase (ALOX15) bei S{\"a}ugetieren und funktionelle Charakterisierung von Knock-in-M{\"a}usen mit humanisierter Reaktionsspezifit{\"a}t der 15-Lipoxygenase-2 (Alox15b)}, doi = {10.25932/publishup-62034}, url = {http://nbn-resolving.de/urn:nbn:de:kobv:517-opus4-620340}, school = {Universit{\"a}t Potsdam}, pages = {XVII, 280}, year = {2024}, abstract = {Arachidons{\"a}urelipoxygenasen (ALOX-Isoformen) sind Lipid-peroxidierenden Enzyme, die bei der Zelldifferenzierung und bei der Pathogenese verschiedener Erkrankungen bedeutsam sind. Im menschlichen Genom gibt es sechs funktionelle ALOX-Gene, die als Einzelkopiegene vorliegen. F{\"u}r jedes humane ALOX-Gen gibt es ein orthologes Mausgen. Obwohl sich die sechs humanen ALOX-Isoformen strukturell sehr {\"a}hnlich sind, unterscheiden sich ihre funktionellen Eigenschaften deutlich voneinander. In der vorliegenden Arbeit wurden vier unterschiedliche Fragestellungen zum Vorkommen, zur biologischen Rolle und zur Evolutionsabh{\"a}ngigkeit der enzymatischen Eigenschaften von S{\"a}ugetier-ALOX-Isoformen untersucht: 1) Spitzh{\"o}rnchen (Tupaiidae) sind evolution{\"a}r n{\"a}her mit dem Menschen verwandt als Nagetiere und wurden deshalb als Alternativmodelle f{\"u}r die Untersuchung menschlicher Erkrankungen vorgeschlagen. In dieser Arbeit wurde erstmals der Arachidons{\"a}urestoffwechsel von Spitzh{\"o}rnchen untersucht. Dabei wurde festgestellt, dass im Genom von Tupaia belangeri vier unterschiedliche ALOX15-Gene vorkommen und die Enzyme sich hinsichtlich ihrer katalytischen Eigenschaften {\"a}hneln. Diese genomische Vielfalt, die weder beim Menschen noch bei M{\"a}usen vorhanden ist, erschwert die funktionellen Untersuchungen zur biologischen Rolle des ALOX15-Weges. Damit scheint Tupaia belangeri kein geeigneteres Tiermodel f{\"u}r die Untersuchung des ALOX15-Weges des Menschen zu sein. 2) Entsprechend der Evolutionshypothese k{\"o}nnen S{\"a}ugetier-ALOX15-Orthologe in Arachidons{\"a}ure-12-lipoxygenierende- und Arachidons{\"a}ure-15-lipoxygenierende Enzyme eingeteilt werden. Dabei exprimieren S{\"a}ugetierspezies, die einen h{\"o}heren Evolutionsgrad als Gibbons aufweisen, Arachidons{\"a}ure-15-lipoxygenierende ALOX15-Orthologe, w{\"a}hrend evolution{\"a}r weniger weit entwickelte S{\"a}ugetiere Arachidons{\"a}ure-12 lipoxygenierende Enzyme besitzen. In dieser Arbeit wurden elf neue ALOX15-Orthologe als rekombinante Proteine exprimiert und funktionell charakterisiert. Die erhaltenen Ergebnisse f{\"u}gen sich widerspruchsfrei in die Evolutionshypothese ein und verbreitern deren experimentelle Basis. Die experimentellen Daten best{\"a}tigen auch das Triadenkonzept. 3) Da humane und murine ALOX15B-Orthologe unterschiedliche funktionelle Eigenschaften aufweisen, k{\"o}nnen Ergebnisse aus murinen Krankheitsmodellen zur biologischen Rolle der ALOX15B nicht direkt auf den Menschen {\"u}bertragen werden. Um die ALOX15B-Orthologen von Maus und Mensch funktionell einander anzugleichen, wurden im Rahmen der vorliegenden Arbeit Knock-in M{\"a}use durch die In vivo Mutagenese mittels CRISPR/Cas9-Technik hergestellt. Diese exprimieren eine humanisierte Mutante (Doppelmutation von Tyrosin603Asparagins{\"a}ure+Histidin604Valin) der murinen Alox15b. Diese M{\"a}use waren lebens- und fortpflanzungsf{\"a}hig, zeigten aber geschlechtsspezifische Unterschiede zu ausgekreuzten Wildtyp-Kontrolltieren im Rahmen ihre Individualentwicklung. 4) In vorhergehenden Untersuchungen zur Rolle der ALOX15B in Rahmen der Entz{\"u}ndungsreaktion wurde eine antiinflammatorische Wirkung des Enzyms postuliert. In der vorliegenden Arbeit wurde untersucht, ob eine Humanisierung der murinen Alox15b die Entz{\"u}ndungsreaktion in zwei verschiedenen murinen Entz{\"u}ndungsmodellen beeinflusst. Eine Humanisierung der murinen Alox15b f{\"u}hrte zu einer verst{\"a}rkten Ausbildung von Entz{\"u}ndungssymptomen im induzierten Dextran-Natrium-Sulfat-Kolitismodell. Im Gegensatz dazu bewirkte die Humanisierung der Alox15b eine Abschw{\"a}chung der Entz{\"u}ndungssymptome im Freund'schen Adjuvans Pfoten{\"o}demmodell. Diese Daten deuten darauf hin, dass sich die Rolle der ALOX15B in verschiedenen Entz{\"u}ndungsmodellen unterscheidet.}, language = {de} } @phdthesis{Szekely2024, author = {Sz{\´e}kely, Andr{\´a}s Csaba}, title = {Long-distance circadian coordination via a phloem-delivered mobile transcript}, school = {Universit{\"a}t Potsdam}, pages = {105}, year = {2024}, language = {en} } @phdthesis{Hammel2024, author = {Hammel, Alexander}, title = {Establishing the red microalga Porphyridium purpureum as a novel platform for the production of recombinant proteins}, doi = {10.25932/publishup-63270}, url = {http://nbn-resolving.de/urn:nbn:de:kobv:517-opus4-632709}, school = {Universit{\"a}t Potsdam}, pages = {ix, 159}, year = {2024}, abstract = {Microalgae have been recognized as a promising green production platform for recombinant proteins. The majority of studies on recombinant protein expression have been conducted in the green microalga C. reinhardtii. While promising improvement regarding nuclear transgene expression in this alga has been made, it is still inefficient due to epigenetic silencing, often resulting in low yields that are not competitive with other expressor organisms. Other microalgal species might be better suited for high-level protein expression, but are limited in their availability of molecular tools. The red microalga Porphyridium purpureum recently emerged as candidate for the production of recombinant proteins. It is promising in that transformation vectors are episomally maintained as autonomously replicating plasmids in the nucleus at a high copy number, thus leading to high expression values in this red alga. In this work, we expand the genetic tools for P. purpureum and investigate parameters that govern efficient transgene expression. We provide an improved transformation protocol to streamline the generation of transgenic lines in this organism. After being able to efficiently generate transgenic lines, we showed that codon usage is a main determinant of high-level transgene expression, not only at the protein level but also at the level of mRNA accumulation. The optimized expression constructs resulted in YFP accumulation up to an unprecedented 5\% of the total soluble protein. Furthermore, we designed new constructs conferring efficient transgene expression into the culture medium, simplifying purification and harvests of recombinant proteins. To further improve transgene expression, we tested endogenous promoters driving the most highly transcribed genes in P. purpureum and found minor increase of YFP accumulation. We employed the previous findings to express complex viral antigens from the hepatitis B virus and the hepatitis C virus in P. purpureum to demonstrate its feasibility as producer of biopharmaceuticals. The viral glycoproteins were successfully produced to high levels and could reach their native confirmation, indicating a functional glycosylation machinery and an appropriate folding environment in this red alga. We could successfully upscale the biomass production of transgenic lines and with that provide enough material for immunization trials in mice that were performed in collaboration. These trials showed no toxicity of neither the biomass nor the purified antigens, and, additionally, the algal-produced antigens were able to elicit a strong and specific immune response. The results presented in this work pave the way for P. purpureum as a new promising producer organism for biopharmaceuticals in the microalgal field.}, language = {en} } @phdthesis{Siebler2024, author = {Siebler, Lara}, title = {Identifying novel regulators of heat stress memory in Arabidopsis thaliana}, doi = {10.25932/publishup-63447}, url = {http://nbn-resolving.de/urn:nbn:de:kobv:517-opus4-634477}, school = {Universit{\"a}t Potsdam}, pages = {135}, year = {2024}, abstract = {Heat stress (HS) is a major abiotic stress that negatively affects plant growth and productivity. However, plants have developed various adaptive mechanisms to cope with HS, including the acquisition and maintenance of thermotolerance, which allows them to respond more effectively to subsequent stress episodes. HS memory includes type II transcriptional memory which is characterized by enhanced re-induction of a subset of HS memory genes upon recurrent HS. In this study, new regulators of HS memory in A. thaliana were identified through the characterization of rein mutants. The rein1 mutant carries a premature stop in CYCLIN-DEPENDENT-KINASE 8 (CDK8) which is part of the cyclin kinase module of the Mediator complex. Rein1 seedlings show impaired type II transcriptional memory in multiple heat-responsive genes upon re-exposure to HS. Additionally, the mutants exhibit a significant deficiency in HS memory at the physiological level. Interaction studies conducted in this work indicate that CDK8 associates with the memory HEAT SHOCK FACTORs HSAF2 and HSFA3. The results suggest that CDK8 plays a crucial role in HS memory in plants together with other memory HSFs, which may be potential targets of the CDK8 kinase function. Understanding the role and interaction network of the Mediator complex during HS-induced transcriptional memory will be an exciting aspect of future HS memory research. The second characterized mutant, rein2, was selected based on its strongly impaired pAPX2::LUC re-induction phenotype. In gene expression analysis, the mutant revealed additional defects in the initial induction of HS memory genes. Along with this observation, basal thermotolerance was impaired similarly as HS memory at the physiological level in rein2. Sequencing of backcrossed bulk segregants with subsequent fine mapping narrowed the location of REIN2 to a 1 Mb region on chromosome 1. This interval contains the At1g65440 gene, which encodes the histone chaperone SPT6L. SPT6L interacts with chromatin remodelers and bridges them to the transcription machinery to regulate nucleosome and Pol II occupancy around the transcriptional start site. The EMS-induced missense mutation in SPT6L may cause altered HS-induced gene expression in rein2, possibly triggered by changes in the chromatin environment resulting from altered histone chaperone function. Expanding research on screen-derived factors that modify type II transcriptional memory has the potential to enhance our understanding of HS memory in plants. Discovering connections between previously identified memory factors will help to elucidate the underlying network of HS memory. This knowledge can initiate new approaches to improve heat resilience in crops.}, language = {en} } @phdthesis{Freimuth2024, author = {Freimuth, Nina}, title = {Elucidating the suppression of root hair formation by a member of a novel, short ENTH protein family in Arabidopsis thaliana}, doi = {10.25932/publishup-63499}, url = {http://nbn-resolving.de/urn:nbn:de:kobv:517-opus4-634994}, school = {Universit{\"a}t Potsdam}, pages = {XIII, 156}, year = {2024}, abstract = {This work analyzed functional and regulatory aspects of the so far little characterized EPSIN N-terminal Homology (ENTH) domain-containing protein EPSINOID2 in Arabidopsis thaliana. ENTH domain proteins play accessory roles in the formation of clathrin-coated vesicles (CCVs) (Zouhar and Sauer 2014). Their ENTH domain interacts with membranes and their typically long, unstructured C-terminus contains binding motifs for adaptor protein complexes and clathrin itself. There are seven ENTH domain proteins in Arabidopsis. Four of them possess the canonical long C-terminus and participate in various, presumably CCV-related intracellular transport processes (Song et al. 2006; Lee et al. 2007; Sauer et al. 2013; Collins et al. 2020; Heinze et al. 2020; Mason et al. 2023). The remaining three ENTH domain proteins, however, have severely truncated C-termini and were termed EPSINOIDs (Zouhar and Sauer 2014; Freimuth 2015). Their functions are currently unclear. Preceding studies focusing on EPSINOID2 indicated a role in root hair formation: epsinoid2 T DNA mutants exhibited an increased root hair density and EPSINOID2-GFP was specifically located in non-hair cell files in the Arabidopsis root epidermis (Freimuth 2015, 2019). In this work, it was clearly shown that loss of EPSINOID2 leads to an increase in root hair density through analyses of three independent mutant alleles, including a newly generated CRISPR/Cas9 full deletion mutant. The ectopic root hairs emerging from non-hair positions in all epsinoid2 mutant alleles are most likely not a consequence of altered cell fate, because extensive genetic analyses placed EPSINOID2 downstream of the established epidermal patterning network. Thus, EPSINOID2 seems to act as a cell autonomous inhibitor of root hair formation. Attempts to confirm this hypothesis by ectopically overexpressing EPSINOID2 led to the discovery of post-transcriptional and -translational regulation through different mechanisms. One involves the little characterized miRNA844-3p. Interference with this pathway resulted in ectopic EPSINOID2 overexpression and decreased root hair density, confirming it as negative factor in root hair formation. A second mechanism likely involves proteasomal degradation. Treatment with proteasomal inhibitor MG132 led to EPSINOID2-GFP accumulation, and a KEN box degron motif was identified in the EPSINOID2 sequence associated with degradation through a ubiquitin/proteasome-dependent pathway. In line with a tight dose regulation, genetic analyses of all three mutant alleles indicate that EPSINOID2 is haploinsufficient. Lastly, it was revealed that, although EPSINOID2 promoter activity was found in all epidermal cells, protein accumulation was observed in N-cells only, hinting at yet another layer of regulation.}, language = {en} } @phdthesis{Hippel2024, author = {Hippel, Barbara von}, title = {Long-term bacteria-fungi-plant associations in permafrost soils inferred from palaeometagenomics}, doi = {10.25932/publishup-63600}, url = {http://nbn-resolving.de/urn:nbn:de:kobv:517-opus4-636009}, school = {Universit{\"a}t Potsdam}, pages = {xii, 198}, year = {2024}, abstract = {The arctic is warming 2 - 4 times faster than the global average, resulting in a strong feedback on northern ecosystems such as boreal forests, which cover a vast area of the high northern latitudes. With ongoing global warming, the treeline subsequently migrates northwards into tundra areas. The consequences of turning ecosystems are complex: on the one hand, boreal forests are storing large amounts of global terrestrial carbon and act as a carbon sink, dragging carbon dioxide out of the global carbon cycle, suggesting an enhanced carbon uptake with increased tree cover. On the other hand, with the establishment of trees, the albedo effect of tundra decreases, leading to enhanced soil warming. Meanwhile, permafrost thaws, releasing large amounts of previously stored carbon into the atmosphere. So far, mainly vegetation dynamics have been assessed when studying the impact of warming onto ecosystems. Most land plants are living in close symbiosis with bacterial and fungal communities, sustaining their growth in nutrient poor habitats. However, the impact of climate change on these subsoil communities alongside changing vegetation cover remains poorly understood. Therefore, a better understanding of soil community dynamics on multi millennial timescales is inevitable when addressing the development of entire ecosystems. Unravelling long-term cross-kingdom dependencies between plant, fungi, and bacteria is not only a milestone for the assessment of warming on boreal ecosystems. On top, it also is the basis for agriculture strategies to sustain society with sufficient food in a future warming world. The first objective of this thesis was to assess ancient DNA as a proxy for reconstructing the soil microbiome (Manuscripts I, II, III, IV). Research findings across these projects enable a comprehensive new insight into the relationships of soil microorganisms to the surrounding vegetation. First, this was achieved by establishing (Manuscript I) and applying (Manuscript II) a primer pair for the selective amplification of ancient fungal DNA from lake sediment samples with the metabarcoding approach. To assess fungal and plant co-variation, the selected primer combination (ITS67, 5.8S) amplifying the ITS1 region was applied on samples from five boreal and arctic lakes. The obtained data showed that the establishment of fungal communities is impacted by warming as the functional ecological groups are shifting. Yeast and saprotroph dominance during the Late Glacial declined with warming, while the abundance of mycorrhizae and parasites increased with warming. The overall species richness was also alternating. The results were compared to shotgun sequencing data reconstructing fungi and bacteria (Manuscripts III, IV), yielding overall comparable results to the metabarcoding approach. Nonetheless, the comparison also pointed out a bias in the metabarcoding, potentially due to varying ITS lengths or copy numbers per genome. The second objective was to trace fungus-plant interaction changes over time (Manuscripts II, III). To address this, metabarcoding targeting the ITS1 region for fungi and the chloroplast P6 loop for plants for the selective DNA amplification was applied (Manuscript II). Further, shotgun sequencing data was compared to the metabarcoding results (Manuscript III). Overall, the results between the metabarcoding and the shotgun approaches were comparable, though a bias in the metabarcoding was assumed. We demonstrated that fungal shifts were coinciding with changes in the vegetation. Yeast and lichen were mainly dominant during the Late Glacial with tundra vegetation, while warming in the Holocene lead to the expansion of boreal forests with increasing mycorrhizae and parasite abundance. Aside, we highlighted that Pinaceae establishment is dependent on mycorrhizal fungi such as Suillineae, Inocybaceae, or Hyaloscypha species also on long-term scales. The third objective of the thesis was to assess soil community development on a temporal gradient (Manuscripts III, IV). Shotgun sequencing was applied on sediment samples from the northern Siberian lake Lama and the soil microbial community dynamics compared to ecosystem turnover. Alongside, podzolization processes from basaltic bedrock were recovered (Manuscript III). Additionally, the recovered soil microbiome was compared to shotgun data from granite and sandstone catchments (Manuscript IV, Appendix). We assessed if the establishment of the soil microbiome is dependent on the plant taxon and as such comparable between multiple geographic locations or if the community establishment is driven by abiotic soil properties and as such the bedrock area. We showed that the development of soil communities is to a great extent driven by the vegetation changes and temperature variation, while time only plays a minor role. The analyses showed general ecological similarities especially between the granite and basalt locations, while the microbiome on species-level was rather site-specific. A greater number of correlated soil taxa was detected for deep-rooting boreal taxa in comparison to grasses with shallower roots. Additionally, differences between herbaceous taxa of the late Glacial compared to taxa of the Holocene were revealed. With this thesis, I demonstrate the necessity to investigate subsoil community dynamics on millennial time scales as it enables further understanding of long-term ecosystem as well as soil development processes and such plant establishment. Further, I trace long-term processes leading to podzolization which supports the development of applied carbon capture strategies under future global warming.}, language = {en} } @phdthesis{Kiss2024, author = {Kiss, Andrea}, title = {Moss-associated bacterial and archaeal communities of northern peatlands: key taxa, environmental drivers and potential functions}, doi = {10.25932/publishup-63064}, url = {http://nbn-resolving.de/urn:nbn:de:kobv:517-opus4-630641}, school = {Universit{\"a}t Potsdam}, pages = {XX, 139, liv}, year = {2024}, abstract = {Moss-microbe associations are often characterised by syntrophic interactions between the microorganisms and their hosts, but the structure of the microbial consortia and their role in peatland development remain unknown. In order to study microbial communities of dominant peatland mosses, Sphagnum and brown mosses, and the respective environmental drivers, four study sites representing different successional stages of natural northern peatlands were chosen on a large geographical scale: two brown moss-dominated, circumneutral peatlands from the Arctic and two Sphagnum-dominated, acidic peat bogs from subarctic and temperate zones. The family Acetobacteraceae represented the dominant bacterial taxon of Sphagnum mosses from various geographical origins and displayed an integral part of the moss core community. This core community was shared among all investigated bryophytes and consisted of few but highly abundant prokaryotes, of which many appear as endophytes of Sphagnum mosses. Moreover, brown mosses and Sphagnum mosses represent habitats for archaea which were not studied in association with peatland mosses so far. Euryarchaeota that are capable of methane production (methanogens) displayed the majority of the moss-associated archaeal communities. Moss-associated methanogenesis was detected for the first time, but it was mostly negligible under laboratory conditions. Contrarily, substantial moss-associated methane oxidation was measured on both, brown mosses and Sphagnum mosses, supporting that methanotrophic bacteria as part of the moss microbiome may contribute to the reduction of methane emissions from pristine and rewetted peatlands of the northern hemisphere. Among the investigated abiotic and biotic environmental parameters, the peatland type and the host moss taxon were identified to have a major impact on the structure of moss-associated bacterial communities, contrarily to archaeal communities whose structures were similar among the investigated bryophytes. For the first time it was shown that different bog development stages harbour distinct bacterial communities, while at the same time a small core community is shared among all investigated bryophytes independent of geography and peatland type. The present thesis displays the first large-scale, systematic assessment of bacterial and archaeal communities associated both with brown mosses and Sphagnum mosses. It suggests that some host-specific moss taxa have the potential to play a key role in host moss establishment and peatland development.}, language = {en} } @article{OgunkolaGuiraudieCaprazFeronetal.2023, author = {Ogunkola, Moses Olalekan and Guiraudie-Capraz, Gaelle and F{\´e}ron, Fran{\c{c}}ois and Leimk{\"u}hler, Silke}, title = {The Human Mercaptopyruvate Sulfurtransferase TUM1 Is Involved in Moco Biosynthesis, Cytosolic tRNA Thiolation and Cellular Bioenergetics in Human Embryonic Kidney Cells}, series = {Biomolecules}, volume = {13}, journal = {Biomolecules}, edition = {1}, publisher = {MDPI}, address = {Basel, Schweiz}, issn = {2218-273X}, doi = {10.3390/biom13010144}, pages = {1 -- 23}, year = {2023}, abstract = {Sulfur is an important element that is incorporated into many biomolecules in humans. The incorporation and transfer of sulfur into biomolecules is, however, facilitated by a series of different sulfurtransferases. Among these sulfurtransferases is the human mercaptopyruvate sulfurtransferase (MPST) also designated as tRNA thiouridine modification protein (TUM1). The role of the human TUM1 protein has been suggested in a wide range of physiological processes in the cell among which are but not limited to involvement in Molybdenum cofactor (Moco) biosynthesis, cytosolic tRNA thiolation and generation of H2S as signaling molecule both in mitochondria and the cytosol. Previous interaction studies showed that TUM1 interacts with the L-cysteine desulfurase NFS1 and the Molybdenum cofactor biosynthesis protein 3 (MOCS3). Here, we show the roles of TUM1 in human cells using CRISPR/Cas9 genetically modified Human Embryonic Kidney cells. Here, we show that TUM1 is involved in the sulfur transfer for Molybdenum cofactor synthesis and tRNA thiomodification by spectrophotometric measurement of the activity of sulfite oxidase and liquid chromatography quantification of the level of sulfur-modified tRNA. Further, we show that TUM1 has a role in hydrogen sulfide production and cellular bioenergetics.}, language = {en} } @article{MarggrafLindeckeVoigtetal.2023, author = {Marggraf, Lara Christin and Lindecke, Oliver and Voigt, Christian C. and Pētersons, Gunārs and Voigt-Heucke, Silke Luise}, title = {Nathusius' bats, Pipistrellus nathusii, bypass mating opportunities of their own species, but respond to foraging heterospecifics on migratory transit flights}, series = {Frontiers in Ecology and Evolution}, journal = {Frontiers in Ecology and Evolution}, publisher = {Frontiers}, address = {Lausanne, Schweiz}, issn = {2296-701X}, doi = {10.3389/fevo.2022.908560}, pages = {1 -- 10}, year = {2023}, abstract = {In late summer, migratory bats of the temperate zone face the challenge of accomplishing two energy-demanding tasks almost at the same time: migration and mating. Both require information and involve search efforts, such as localizing prey or finding potential mates. In non-migrating bat species, playback studies showed that listening to vocalizations of other bats, both con-and heterospecifics, may help a recipient bat to find foraging patches and mating sites. However, we are still unaware of the degree to which migrating bats depend on con-or heterospecific vocalizations for identifying potential feeding or mating opportunities during nightly transit flights. Here, we investigated the vocal responses of Nathusius' pipistrelle bats, Pipistrellus nathusii, to simulated feeding and courtship aggregations at a coastal migration corridor. We presented migrating bats either feeding buzzes or courtship calls of their own or a heterospecific migratory species, the common noctule, Nyctalus noctula. We expected that during migratory transit flights, simulated feeding opportunities would be particularly attractive to bats, as well as simulated mating opportunities which may indicate suitable roosts for a stopover. However, we found that when compared to the natural silence of both pre-and post-playback phases, bats called indifferently during the playback of conspecific feeding sounds, whereas P. nathusii echolocation call activity increased during simulated feeding of N. noctula. In contrast, the call activity of P. nathusii decreased during the playback of conspecific courtship calls, while no response could be detected when heterospecific call types were broadcasted. Our results suggest that while on migratory transits, P. nathusii circumnavigate conspecific mating aggregations, possibly to save time or to reduce the risks associated with social interactions where aggression due to territoriality might be expected. This avoidance behavior could be a result of optimization strategies by P. nathusii when performing long-distance migratory flights, and it could also explain the lack of a response to simulated conspecific feeding. However, the observed increase of activity in response to simulated feeding of N. noctula, suggests that P. nathusii individuals may be eavesdropping on other aerial hawking insectivorous species during migration, especially if these occupy a slightly different foraging niche.}, language = {en} } @phdthesis{Artins2023, author = {Artins, Anthony}, title = {Crosstalk between Target Of Rapamycin (TOR) and sugar signaling in Arabidopsis thaliana}, school = {Universit{\"a}t Potsdam}, pages = {125}, year = {2023}, language = {en} } @phdthesis{Amen2023, author = {Amen, Rahma}, title = {Adaptive radiation in African weakly electric fish genus Campylomormyrus}, school = {Universit{\"a}t Potsdam}, pages = {XIV, 155}, year = {2023}, abstract = {The African weakly electric fish genus Campylomormyrus includes 15 described species mostly native to the Congo River and its tributaries. They are considered sympatric species, because their distribution area overlaps. These species generate species-specific electric organ discharges (EODs) varying in waveform characteristics, including duration, polarity, and phase number. They exhibit also pronounced divergence in their snout, i.e. the length, thickness, and curvature. The diversifications in these two phenotypical traits (EOD and snout) have been proposed as key factors promoting adaptive radiation in Campylomormyrus. The role of EODs as a pre-zygotic isolation mechanism driving sympatric speciation by promoting assortative mating has been examined using behavioral, genetical, and histological approaches. However, the evolutionary effects of the snout morphology and its link to species divergence have not been closely examined. Hence, the main objective of this study is to investigate the effect of snout morphology diversification and its correlated EOD to better understand their sympatric speciation and evolutionary drivers. Moreover, I aim to utilize the intragenus and intergenus hybrids of Campylomormyrus to better understand trait divergence as well as underlying molecular/genetic mechanisms involved in the radiation scenario. To this end, I utilized three different approaches: feeding behavior analysis, diet assessment, and geometric morphometrics analysis. I performed feeding behavior experiments to evaluate the concept of the phenotype-environment correlation by testing whether Campylomormyrus species show substrate preferences. The behavioral experiments showed that the short snout species exhibits preference to sandy substrate, the long snout species prefers a stone substrate, and the species with intermediate snout size does not exhibit any substrate preference. The experiments suggest that the diverse feeding apparatus in the genus Campylomormyrus may have evolved in adaptation to their microhabitats. I also performed diet assessments of sympatric Campylomormyrus species and a sister genus species (Gnathonemus petersii) with markedly different snout morphologies and EOD using NGS-based DNA metabarcoding of their stomach contents. The diet of each species was documented showing that aquatic insects such as dipterans, coleopterans and trichopterans represent the major diet component. The results showed also that all species are able to exploit diverse food niches in their habitats. However, comparing the diet overlap indices showed that different snout morphologies and the associated divergence in the EOD translated into different prey spectra. These results further support the idea that the EOD could be a 'magic trait' triggering both adaptation and reproductive isolation. Geometric morphometrics method was also used to compare the phenotypical shape traits of the F1 intragenus (Campylomormyrus) and intergenus (Campylomormyrus species and Gnathonemus petersii) hybrids relative to their parents. The hybrids of these species were well separated based on the morphological traits, however the hybrid phenotypic traits were closer to the short-snouted species. In addition, the likelihood that the short snout expressed in the hybrids increases with increasing the genetic distance of the parental species. The results confirmed that additive effects produce intermediate phenotypes in F1-hybrids. It seems, therefore, that morphological shape traits in hybrids, unlike the physiological traits, were not expressed straightforward.}, language = {en} } @phdthesis{MartinezSeidel2023, author = {Martinez-Seidel, Federico}, title = {Ribosome Heterogeneity and Specialization during Temperature Acclimation in Plants}, doi = {10.25932/publishup-58072}, url = {http://nbn-resolving.de/urn:nbn:de:kobv:517-opus4-580724}, school = {Universit{\"a}t Potsdam}, pages = {374}, year = {2023}, abstract = {Ribosomes decode mRNA to synthesize proteins. Ribosomes, once considered static, executing machines, are now viewed as dynamic modulators of translation. Increasingly detailed analyses of structural ribosome heterogeneity led to a paradigm shift toward ribosome specialization for selective translation. As sessile organisms, plants cannot escape harmful environments and evolved strategies to withstand. Plant cytosolic ribosomes are in some respects more diverse than those of other metazoans. This diversity may contribute to plant stress acclimation. The goal of this thesis was to determine whether plants use ribosome heterogeneity to regulate protein synthesis through specialized translation. I focused on temperature acclimation, specifically on shifts to low temperatures. During cold acclimation, Arabidopsis ceases growth for seven days while establishing the responses required to resume growth. Earlier results indicate that ribosome biogenesis is essential for cold acclimation. REIL mutants (reil-dkos) lacking a 60S maturation factor do not acclimate successfully and do not resume growth. Using these genotypes, I ascribed cold-induced defects of ribosome biogenesis to the assembly of the polypeptide exit tunnel (PET) by performing spatial statistics of rProtein changes mapped onto the plant 80S structure. I discovered that growth cessation and PET remodeling also occurs in barley, suggesting a general cold response in plants. Cold triggered PET remodeling is consistent with the function of Rei-1, a REIL homolog of yeast, which performs PET quality control. Using seminal data of ribosome specialization, I show that yeast remodels the tRNA entry site of ribosomes upon change of carbon sources and demonstrate that spatially constrained remodeling of ribosomes in metazoans may modulate protein synthesis. I argue that regional remodeling may be a form of ribosome specialization and show that heterogeneous cytosolic polysomes accumulate after cold acclimation, leading to shifts in the translational output that differs between wild-type and reil-dkos. I found that heterogeneous complexes consist of newly synthesized and reused proteins. I propose that tailored ribosome complexes enable free 60S subunits to select specific 48S initiation complexes for translation. Cold acclimated ribosomes through ribosome remodeling synthesize a novel proteome consistent with known mechanisms of cold acclimation. The main hypothesis arising from my thesis is that heterogeneous/ specialized ribosomes alter translation preferences, adjust the proteome and thereby activate plant programs for successful cold acclimation.}, language = {en} } @phdthesis{GonzalezDuran2023, author = {Gonzalez Duran, Enrique}, title = {Genetic control of intracellular gene transfer by DNA repair in N. tabacum}, school = {Universit{\"a}t Potsdam}, pages = {XII, 127, XLI}, year = {2023}, abstract = {Mitochondria and plastids are organelles with an endosymbiotic origin. During evolution, many genes are lost from the organellar genomes and get integrated in the nuclear genome, in what is known as intracellular/endosymbiotic gene transfer (IGT/EGT). IGT has been reproduced experimentally in Nicotiana tabacum at a gene transfer rate (GTR) of 1 event in 5 million cells, but, despite its centrality to eukaryotic evolution, there are no genetic factors known to influence the frequency of IGT in higher eukaryotes. The focus of this work was to determine the role of different DNA repair pathways of double strand break repair (DSBR) in the integration step of organellar DNA in the nuclear genome during IGT. Here, a CRISPR/Cas9 mutagenesis strategy was implemented in N. tabacum, with the aim of generating mutants in nuclear genes without expected visible phenotypes. This strategy led to the generation of a collection of independent mutants in the LIG4 (necessary for non-homologous end joining, NHEJ) and POLQ genes (necessary for microhomology mediated end joining, MMEJ). Targeting of other DSBR genes (KU70, KU80, RPA1C) generated mutants with unexpectedly strong developmental phenotypes.. These factors have telomeric roles, hinting towards a possible relationship between telomere length, and strength of developmental disruption upon loss of telomere structure in plants. The mutants were made in a genetic background encoding a plastid-encoded IGT reporter, that confers kanamycin resistance upon transfer to the nucleus. Through large scale independent experiments, increased IGT from the chloroplast to the nucleus was observed in lig4 mutants, as well as lines encoding a POLQ gene with a defective polymerase domain (polqΔPol). This shows that NHEJ or MMEJ have a double-sided relationship with IGT: while transferred genes may integrate using either pathway, the presence of both pathways suppresses IGT in wild-type somatic cells, thus demonstrating for the first time the extent on which nuclear genes control IGT frequency in plants. The IGT frequency increases in the mutants are likely mediated by increased availability of double strand breaks for integration. Additionally, kinetic analysis reveals that gene transfer (GT) events accumulate linearly as a function of time spent under antibiotic selection in the experiment, demonstrating that, contrary to what was previously thought, there is no such thing as a single GTR in somatic IGT experiments. Furthermore, IGT in tissue culture experiments appears to be the result of a "race against the clock" for integration in the nuclear genome, that starts when the organellar DNA arrives to the nucleus granting transient antibiotic resistance. GT events and escapes of kanamycin selection may be two possible outcomes from this race: those instances where the organellar DNA gets to integrate are recovered as GT events, and in those cases where timely integration fails, antibiotic resistance cannot be sustained, and end up considered as escapes. In the mutants, increased opportunities for integration in the nuclear genome change the overall ratio between IGT and escape events. The resources generated here are promising starting points for future research: (1) the mutant collection, for the further study of processes that depend on DNA repair in plants (2) the collection of GT lines obtained from these experiments, for the study of the effect of DSBR pathways over integration patterns and stability of transferred genes and (3) the developed CRISPR/Cas9 workflow for mutant generation, to make N. tabacum meet its potential as an attractive model for answering complex biological questions.}, language = {en} } @phdthesis{Buehler2023, author = {B{\"u}hler, Miriam}, title = {The role of (xeno)hormone-activated GPER1 for centrosome amplification and whole chromosomal instability in colon cell lines}, school = {Universit{\"a}t Potsdam}, pages = {IX, 144}, year = {2023}, abstract = {The G protein-coupled estrogen receptor (GPER1) is acknowledged as an important mediator of estrogen signaling. Given the ubiquitous expression of GPER1, it is likely that the receptor plays a role in a variety of malignancies, not only in the classic hormonally regulated tissues (e.g., breast, ovary, and prostate), but also in the colon. As colorectal cancer (CRC) is the third most common cancer in both men and women worldwide and environmental factors and dietary habits are important risk factors, it is increasingly recognized that natural and synthetic hormones and their associated receptors might play a role in CRC. Through oral consumption, environmental contaminants with endocrine activity are in contact with the gastrointestinal mucosa, where they might exert their toxic effects. Although GPER1 has been shown to be engaged in physiological and pathophysiological processes, its role in CRC remains poorly understood. Thus, pro- as well as anti-tumorigenic effects are described in the literature. This thesis has uncovered novel roles of GPER1 in mediating major CRC-associated phenotypes in transformed and non-transformed colon cell lines. Exposure to the estrogens 17β-estradiol (E2), bisphenol-A (BPA) and diethylstilbestrol (DES) but also the androgen dihydrotestosterone (DHT) resulted in GPER1-dependent induction of supernumerary centrosomes, whole chromosomal instability (w-CIN) and aneuploidy. Indeed, both knockdown and inhibition of GPER1 attenuated the generation of (xeno)hormone-driven supernumerary centrosomes and karyotype instability. Mechanistically, (xeno)hormone-induced centrosome amplification was associated with transient multipolar mitosis and the generation of so called anaphase "lagging" chromosomes. The results of this thesis propose a GPER1/PKA/AKAP9-pathway in regulating centrosome numbers in colorectal cancer cells and the involvement of the centriolar protein centrin. Remarkably, exposure to (xeno)hormones resulted in atypical enlargement and unexpected phosphorylation of the centriole marker centrin in interphase. These findings provide a novel role for GPER1 in key CRC-prone lesions and shed light on underlying mechanisms that involve GPER1 function in the colon. Elucidating to what extent centrosomal proteins are involved in the GPER1-mediated aneugenic effect will be an important task for future studies. The present study was intended to lay a first foundation to understand the molecular basis and potential risk factors of CRC which might help to reduce the use of laboratory animals. Since numerous animal experiments are conducted in biomedical research, the development of alternative methods is indispensable. The Federal Institute for Risk Assessment (BfR) as the German Center for the Protection of Laboratory Animals (Bf3R) addresses this issue by uncovering underlying mechanisms leading to colorectal cancer as necessary prerequisite in order to develop alternative methods.}, language = {en} } @phdthesis{vonBismarck2023, author = {von Bismarck, Thekla}, title = {The influence of long-term light acclimation on photosynthesis in dynamic light}, school = {Universit{\"a}t Potsdam}, pages = {x, 163}, year = {2023}, abstract = {Photosynthesis converts light into metabolic energy which fuels plant growth. In nature, many factors influence light availability for photosynthesis on different time scales, from shading by leaves within seconds up to seasonal changes over months. Variability of light energy supply for photosynthesis can limit a plant´s biomass accumulation. Plants have evolved multiple strategies to cope with strongly fluctuation light (FL). These range from long-term optimization of leaf morphology and physiology and levels of pigments and proteins in a process called light acclimation, to rapid changes in protein activity within seconds. Therefore, uncovering how plants deal with FL on different time scales may provide key ideas for improving crop yield. Photosynthesis is not an isolated process but tightly integrates with metabolism through mutual regulatory interactions. We thus require mechanistic understanding of how long-term light acclimation shapes both, dynamic photosynthesis and its interactions with downstream metabolism. To approach this, we analyzed the influence of growth light on i) the function of known rapid photosynthesis regulators KEA3 and VCCN1 in dynamic photosynthesis (Chapter 2-3) and ii) the interconnection of photosynthesis with photorespiration (PR; Chapter 4). We approached topic (i) by quantifying the effect of different growth light regimes on photosynthesis and photoprotection by using kea3 and vccn1 mutants. Firstly, we found that, besides photosynthetic capacity, the activities of VCCN1 and KEA3 during a sudden high light phase also correlated with growth light intensity. This finding suggests regulation of both proteins by the capacity of downstream metabolism. Secondly, we showed that KEA3 accelerated photoprotective non-photochemical quenching (NPQ) kinetics in two ways: Directly via downregulating the lumen proton concentration and thereby de-activating pH-dependent NPQ, and indirectly via suppressing accumulation of the photoprotective pigment zeaxanthin. For topic (ii), we analyzed the role of PR, a process which recycles a toxic byproduct of the carbon fixation reactions, in metabolic flexibility in a dynamically changing light environment. For this we employed the mutants hpr1 and ggt1 with a partial block in PR. We characterized the function of PR during light acclimation by tracking molecular and physiological changes of the two mutants. Our data, in contrast to previous reports, disprove a generally stronger physiological relevance of PR under dynamic light conditions. Additionally, the two different mutants showed pronounced and distinct metabolic changes during acclimation to a condition inducing higher photosynthetic activity. This underlines that PR cannot be regarded purely as a cyclic detoxification pathway for 2PG. Instead, PR is highly interconnected with plant metabolism, with GGT1 and HPR1 representing distinct metabolic modulators. In summary, the presented work provides further insight into how energetic and metabolic flexibility is ensured by short-term regulators and PR during long-term light acclimation.}, language = {en} } @phdthesis{Rolo2023, author = {Rolo, David}, title = {Assembly of photosystem I in thylakoid membranes}, school = {Universit{\"a}t Potsdam}, pages = {177}, year = {2023}, abstract = {The light reactions of photosynthesis are carried out by a series of multiprotein complexes embedded in thylakoid membranes. Among them, photosystem I (PSI), acting as plastocyanin-ferderoxin oxidoreductase, catalyzes the final reaction. Together with light-harvesting antenna I, PSI forms a high-molecular-weight supercomplex of ~600 kDa, consisting of eighteen subunits and nearly two hundred co-factors. Assembly of the various components into a functional thylakoid membrane complex requires precise coordination, which is provided by the assembly machinery. Although this includes a small number of proteins (PSI assembly factors) that have been shown to play a role in the formation of PSI, the process as a whole, as well as the intricacy of its members, remains largely unexplored. In the present work, two approaches were used to find candidate PSI assembly factors. First, EnsembleNet was used to select proteins thought to be functionally related to known PSI assembly factors in Arabidopsis thaliana (approach I), and second, co-immunoprecipitation (Co-IP) of tagged PSI assembly factors in Nicotiana tabacum was performed (approach II). Here, the novel PSI assembly factors designated CO-EXPRESSED WITH PSI ASSEMBLY 1 (CEPA1) and Ycf4-INTERACTING PROTEIN 1 (Y4IP1) were identified. A. thaliana null mutants for CEPA1 and Y4IP1 showed a growth phenotype and pale leaves compared with the wild type. Biophysical experiments using pulse amplitude modulation (PAM) revealed insufficient electron transport on the PSII acceptor side. Biochemical analyses revealed that both CEPA1 and Y4IP1 are specifically involved in PSI accumulation in A. thaliana at the post-translational level but are not essential. Consistent with their roles as factors in the assembly of a thylakoid membrane protein complex, the two proteins localize to thylakoid membranes. Remarkably, cepa1 y4ip1 double mutants exhibited lethal phenotypes in early developmental stages under photoautotrophic growth. Finally, co-IP and native gel experiments supported a possible role for CEPA1 and Y4IP1 in mediating PSI assembly in conjunction with other PSI assembly factors (e.g., PPD1- and PSA3-CEPA1 and Ycf4-Y4IP1). The fact that CEPA1 and Y4IP1 are found exclusively in green algae and higher plants suggests eukaryote-specific functions. Although the specific mechanisms need further investigation, CEPA1 and Y4IP1 are two novel assembly factors that contribute to PSI formation.}, language = {en} } @phdthesis{Derežanin2023, author = {Derežanin, Lorena}, title = {Contribution of structural variation to adaptive evolution of mammalian genomes}, doi = {10.25932/publishup-59144}, url = {http://nbn-resolving.de/urn:nbn:de:kobv:517-opus4-591443}, school = {Universit{\"a}t Potsdam}, pages = {188}, year = {2023}, abstract = {Following the extinction of dinosaurs, the great adaptive radiation of mammals occurred, giving rise to an astonishing ecological and phenotypic diversity of mammalian species. Even closely related species often inhabit vastly different habitats, where they encounter diverse environmental challenges and are exposed to different evolutionary pressures. As a response, mammals evolved various adaptive phenotypes over time, such as morphological, physiological and behavioural ones. Mammalian genomes vary in their content and structure and this variation represents the molecular mechanism for the long-term evolution of phenotypic variation. However, understanding this molecular basis of adaptive phenotypic variation is usually not straightforward. The recent development of sequencing technologies and bioinformatics tools has enabled a better insight into mammalian genomes. Through these advances, it was acknowledged that mammalian genomes differ more, both within and between species, as a consequence of structural variation compared to single-nucleotide differences. Structural variant types investigated in this thesis - such as deletion, duplication, inversion and insertion, represent a change in the structure of the genome, impacting the size, copy number, orientation and content of DNA sequences. Unlike short variants, structural variants can span multiple genes. They can alter gene dosage, and cause notable gene expression differences and subsequently phenotypic differences. Thus, they can lead to a more dramatic effect on the fitness (reproductive success) of individuals, local adaptation of populations and speciation. In this thesis, I investigated and evaluated the potential functional effect of structural variations on the genomes of mustelid species. To detect the genomic regions associated with phenotypic variation I assembled the first reference genome of the tayra (Eira barbara) relying on linked-read sequencing technology to achieve a high level of genome completeness important for reliable structural variant discovery. I then set up a bioinformatics pipeline to conduct a comparative genomic analysis and explore variation between mustelid species living in different environments. I found numerous genes associated with species-specific phenotypes related to diet, body condition and reproduction among others, to be impacted by structural variants. Furthermore, I investigated the effects of artificial selection on structural variants in mice selected for high fertility, increased body mass and high endurance. Through selective breeding of each mouse line, the desired phenotypes have spread within these populations, while maintaining structural variants specific to each line. In comparison to the control line, the litter size has doubled in the fertility lines, individuals in the high body mass lines have become considerably larger, and mice selected for treadmill performance covered substantially more distance. Structural variants were found in higher numbers in these trait-selected lines than in the control line when compared to the mouse reference genome. Moreover, we have found twice as many structural variants spanning protein-coding genes (specific to each line) in trait-selected lines. Several of these variants affect genes associated with selected phenotypic traits. These results imply that structural variation does indeed contribute to the evolution of the selected phenotypes and is heritable. Finally, I suggest a set of critical metrics of genomic data that should be considered for a stringent structural variation analysis as comparative genomic studies strongly rely on the contiguity and completeness of genome assemblies. Because most of the available data used to represent reference genomes of mammalian species is generated using short-read sequencing technologies, we may have incomplete knowledge of genomic features. Therefore, a cautious structural variation analysis is required to minimize the effect of technical constraints. The impact of structural variants on the adaptive evolution of mammalian genomes is slowly gaining more focus but it is still incorporated in only a small number of population studies. In my thesis, I advocate the inclusion of structural variants in studies of genomic diversity for a more comprehensive insight into genomic variation within and between species, and its effect on adaptive evolution.}, language = {en} } @phdthesis{Leer2023, author = {Leer, Marina}, title = {Computational analysis of the effects of ageing and diet on stem cell function and ectopic fat accumulation in the musculoskeletal system}, school = {Universit{\"a}t Potsdam}, pages = {130}, year = {2023}, abstract = {The musculoskeletal system provides support and enables movement to the body, and its deterioration is a crucial aspect of age-related functional decline. Mesenchymal stromal cells (MSCs) play an important role in musculoskeletal homeostasis due to their broad differentiation potentials and their ability to support osteogenic and myogenic tissue maintenance and regeneration. In the bone, MSCs differentiate either into osteochondrogenic progenitors to form osteocytes and chondrocytes, or increasingly with age into adipogenic progenitors which give rise to bone-resident adipocytes. In skeletal muscle, during healthy regeneration MSCs provide regulatory signals that activate local, tissue-specific stem cells, known as satellite cells, which regenerate contractile myofibres. This process involves a significant cross-talk to immune cells stemming from both lymphoid and myeloid lineages. During ageing, muscle-resident MSCs undergo increased adipogenic lineage commitment, causing niche changes that contribute to fatty infiltration in muscles. These shifts in cell populations in bone lead to the loss of osteogenic cells and subsequently osteoporosis, or in muscle to impaired regeneration and to the development of sarcopenia. However, the signals that drive transition of MSCs into their respective cellular fates remain elusive. This thesis aims to elucidate the transcriptional shifts modulating cell states and cell types in musculoskeletal MSC fate determination. Single-cell RNA-sequencing (scRNA-seq) was used to characterise cell type-specific transcript regulation. State-of-the-art bioinformatics tools were combined with different analytical platforms that include both droplet-based scRNA-seq for large heterogeneous populations, and microfluidics-based scRNA-seq to assess small, rare subpopulations. For each platform, distinct computational pipelines were established including filtering steps to exclude low-quality cells, and data visualisation was performed by dimensionality reduction. Downstream analysis included clustering, cell type annotation, and differential gene expression to investigate transcriptional states in defined cell types during ageing and injury in the muscle and bone. Finally, a novel tool to assess publication activities in defined areas of research for the identified marker genes was developed. The results in the bone indicate that ageing MSCs increasingly commit towards an adipogenic fate at the expense of osteogenic specialisation. The data also suggests that significant cell population shifts of MSC-type fibro-adipogenic progenitors during muscle ageing underlie the pathologies observed in homeostatic and post-injury regenerative conditions. High-throughput visualisation of publication activity for candidate genes enabled more effective biological evaluation of scRNA-seq data. These results expose critical age-related changes in the stem cell niches of skeletal muscle and bone, highlight their respective sensitivity to nutrition and pathology, and elucidate novel factors that modulate stem cell-based regeneration. Targeting these processes might improve musculoskeletal health in the context of ageing and prevent the negative effects of pathological lineage determination.}, language = {en} } @phdthesis{KoikkarahAji2023, author = {Koikkarah Aji, Amit}, title = {Quantitative sub cellular characterization of Hantavirus structural proteins}, doi = {10.25932/publishup-58661}, url = {http://nbn-resolving.de/urn:nbn:de:kobv:517-opus4-586612}, school = {Universit{\"a}t Potsdam}, pages = {101}, year = {2023}, abstract = {Hantaviruses (HVs) are a group of zoonotic viruses that infect human beings primarily through aerosol transmission of rodent excreta and urine samplings. HVs are classified geographically into: Old World HVs (OWHVs) that are found in Europe and Asia, and New World HVs (NWHVs) that are observed in the Americas. These different strains can cause severe hantavirus diseases with pronounced renal syndrome or severe cardiopulmonary system distress. HVs can be extremely lethal, with NWHV infections reaching up to 40 \% mortality rate. HVs are known to generate epidemic outbreaks in many parts of the world including Germany, which has seen periodic HV infections over the past decade. HV has a trisegmented genome. The small segment (S) encodes the nucleocapsid protein (NP), the middle segment (M) encodes the glycoproteins (GPs) Gn and Gc which forms up to tetramers and primarily monomers \\& dimers upon independent expression respectively and large segment (L) encodes RNA dependent RNA polymerase (RdRp). Interactions between these viral proteins are crucial in providing mechanistic insights into HV virion development. Despite best efforts, there continues to be lack of quantification of these associations in living cells. This is required in developing the mechanistic models for HV viral assembly. This dissertation focuses on three key questions pertaining to the initial steps of virion formation that primarily involves the GPs and NP. The research investigations in this work were completed using Fluorescence Correlation Spectroscopy (FCS) approaches. FCS is frequently used in assessing the biophysical features of bio-molecules including protein concentration and diffusion dynamics and circumvents the requirement of protein overexpression. FCS was primarily applied in this thesis to evaluate protein multimerization, at single cell resolution. The first question addressed which GP spike formation model proposed by Hepojoki et al.(2010) appropriately describes the evidence in living cells. A novel in cellulo assay was developed to evaluate the amount of fluorescently labelled and unlabeled GPs upon co-expression. The results clearly showed that Gn and Gc initially formed a heterodimeric Gn:Gc subunit. This sub-unit then multimerizes with congruent Gn:Gc subunits to generate the final GP spike. Based on these interactions, models describing the formation of GP complex (with multiple GP spike subunits) were additionally developed. HV GP assembly primarily takes place in the Golgi apparatus (GA) of infected cells. Interestingly, NWHV GPs are hypothesized to assemble at the plasma membrane (PM). This led to the second research question in this thesis, in which a systematic comparison between OWHV and NWHV GPs was conducted to validate this hypothesis. Surprisingly, GP localization at the PM was congruently observed with OWHV and NWHV GPs. Similar results were also discerned with OWHV and NWHV GP localization in the absence of cytoskeletal factors that regulate HV trafficking in cells. The final question focused on quantifying the NP-GP interactions and understanding their influence of NP and GP multimerization. Gc mutlimers were detected in the presence of NP and complimented by the presence of localized regions of high NP-Gc interactions in the perinuclear region of living cells. Gc-CT domain was shown to influence NP-Gc associations. Gn, on the other hand, formed up to tetrameric complexes, independent from the presence of NP. The results in this dissertation sheds light on the initial steps of HV virion formation by quantifying homo and heterotypic interactions involving NP and GPs, which otherwise are very difficult to perform. Finally, the in cellulo methodologies implemented in this work can be potentially extended to understand other key interactions involved in HV virus assembly.}, language = {en} } @phdthesis{Gaetjen2023, author = {G{\"a}tjen, Dominic}, title = {A Pichia pastoris surface display system for the efficient screening of high-producing antibody clones}, school = {Universit{\"a}t Potsdam}, pages = {120}, year = {2023}, abstract = {Pichia pastoris (syn. Komagataella phaffi) is a distinguished expression system widely used in industrial production processes. Recent molecular research has focused on numerous approaches to increase recombinant protein yield in P. pastoris. For example, the design of expression vectors and synthetic genetic elements, gene copy number optimization, or co-expression of helper proteins (transcription factors, chaperones, etc.). However, high clonal variability of transformants and low screening throughput have hampered significant success. To enhance screening capacities, display-based methodologies inherit the potential for efficient isolation of producer clones via fluorescence-activated cell sorting (FACS). Therefore, this study focused on developing a novel clone selection method that is based on the non-covalent attachment of Fab fragments on the P. pastoris cell surface to be applicable for FACS. Initially, a P. pastoris display system was developed, which is a prerequisite for the surface capture of secreted Fabs. A Design of Experiments approach was applied to analyze the influence of various genetic elements on antibody fragment display. The combined P. pastoris formaldehyde dehydrogenase promoter (PFLD1), Saccharomyces cerevisiae invertase 2 signal peptide (ScSUC2), - agglutinin (ScSAG1) anchor protein, and the ARS of Kluyveromyces lactis (panARS) conferred highest display levels. Subsequently, eight single-chain variable fragments (scFv) specific for the constant part of the Fab heavy or light chain were individually displayed in P. pastoris. Among the tested scFvs, the anti-human CH1 IgG domain scFv allowed the most efficient Fab capture detected by flow cytometry. Irrespective of the Fab sequence, exogenously added as well as simultaneously secreted Fabs were successfully captured on the cell surface. Furthermore, Fab secretion capacities were shown to correlate to the level of surface-bound Fabs as demonstrated for characterized producer clones. Flow-sorted clones presenting high amounts of Fabs showed an increase in median Fab titers (factor of 21 to 49) compared to unsorted clones when screened in deep-well plates. For selected candidates, improved functional Fab yields of sorted cells vs. unsorted cells were confirmed in an upscaled shake flask production. Since the scFv capture matrix was encoded on an episomal plasmid with inherently unstable autonomously replicating sequences (ARS), efficient plasmid curing was observed after removing the selective pressure. Hence, sorted clones could be immediately used for production without the need to modify the expression host or vector. The resulting switchable display/secretion system provides a streamlined approach for the isolation of Fab producers and subsequent Fab production.}, language = {en} } @phdthesis{Riedel2023, author = {Riedel, Soraya Lisanne}, title = {Development of electrochemical antibody-based and enzymatic assays for mycotoxin analysis in food}, doi = {10.25932/publishup-60747}, url = {http://nbn-resolving.de/urn:nbn:de:kobv:517-opus4-607477}, school = {Universit{\"a}t Potsdam}, pages = {XV, 95}, year = {2023}, abstract = {Electrochemical methods are promising to meet the demand for easy-to-use devices monitoring key parameters in the food industry. Many companies run own lab procedures for mycotoxin analysis, but it is a major goal to simplify the analysis. The enzyme-linked immunosorbent assay using horseradish peroxidase as enzymatic label, together with 3,3',5,5' tetramethylbenzidine (TMB)/H2O2 as substrates allows sensitive mycotoxin detection with optical detection methods. For the miniaturization of the detection step, an electrochemical system for mycotoxin analysis was developed. To this end, the electrochemical detection of TMB was studied by cyclic voltammetry on different screen-printed electrodes (carbon and gold) and at different pH values (pH 1 and pH 4). A stable electrode reaction, which is the basis for the further construction of the electrochemical detection system, could be achieved at pH 1 on gold electrodes. An amperometric detection method for oxidized TMB, using a custom-made flow cell for screen-printed electrodes, was established and applied for a competitive magnetic bead-based immunoassay for the mycotoxin ochratoxin A. A limit of detection of 150 pM (60 ng/L) could be obtained and the results were verified with optical detection. The applicability of the magnetic bead-based immunoassay was tested in spiked beer using a handheld potentiostat connected via Bluetooth to a smartphone for amperometric detection allowing to quantify ochratoxin A down to 1.2 nM (0.5 µg/L). Based on the developed electrochemical detection system for TMB, the applicability of the approach was demonstrated with a magnetic bead-based immunoassay for the ergot alkaloid, ergometrine. Under optimized assay conditions a limit of detection of 3 nM (1 µg/L) was achieved and in spiked rye flour samples ergometrine levels in a range from 25 to 250 µg/kg could be quantified. All results were verified with optical detection. The developed electrochemical detection method for TMB gives great promise for the detection of TMB in many other HRP-based assays. A new sensing approach, based on an enzymatic electrochemical detection system for the mycotoxin fumonisin B1 was established using an Aspergillus niger fumonisin amine oxidase (AnFAO). AnFAO was produced recombinantly in E. coli as maltose-binding protein fusion protein and catalyzes the oxidative deamination of fumonisins, producing hydrogen peroxide. It was found that AnFAO has a high storage and temperature stability. The enzyme was coupled covalently to magnetic particles, and the enzymatically produced H2O2 in the reaction with fumonisin B1 was detected amperometrically in a flow injection system using Prussian blue/carbon electrodes and the custom-made wall-jet flow cell. Fumonisin B1 could be quantified down to 1.5 µM (≈ 1 mg/L). The developed system represents a new approach to detect mycotoxins using enzymes and electrochemical methods.}, language = {en} } @article{TaguchiGotoMatsuokaetal.2023, author = {Taguchi, Mioko and Goto, Mutsuo and Matsuoka, Koji and Tiedemann, Ralph and Pastene, Luis A.}, title = {Population genetic structure of Bryde's whales (Balaenoptera brydei) on the central and western North Pacific feeding grounds}, series = {Canadian Journal of Fisheries and Aquatic Sciences}, volume = {80}, journal = {Canadian Journal of Fisheries and Aquatic Sciences}, number = {1}, publisher = {Canadian science publishing}, address = {Ottawa}, issn = {0706-652X}, doi = {10.1139/cjfas-2022-0005}, pages = {142 -- 155}, year = {2023}, abstract = {The genetic structure of Bryde's whale (Balaenoptera brydei) on the central and western North Pacific feeding grounds was investigated using a total of 1195 mitochondrial control region sequences and 1182 microsatellite genotypes at 17 loci in specimens collected from three longitudinal areas, 1W (135 degrees E-165 degrees E), 1E (165 degrees E-180 degrees), and 2 (180 degrees-155 degrees W). Genetic diversities were similar among areas and a haplotype network did not show any geographic structure, while an analysis of molecular variance found evidence of genetic structure in this species. Pairwise FST and G'ST estimates and heterogeneity tests attributed this structure to weak but significant differentiation between areas 1W/1E and 2. A Mantel test and a high-resolution analysis of genetic diversity statistics showed a weak spatial cline of genetic differentiation. These findings could be reconciled by two possible stock structure scenarios: (1) a single population with kin-association affecting feeding ground preference and (2) two populations with feeding ground preference for either area 1W or area 2. An estimated dispersal rate between areas 1W and 2 indicates that both scenarios should be considered as a precautionary principle in stock assessments.}, language = {en} } @phdthesis{Gramma2023, author = {Gramma, Vladislav}, title = {Potato FLC-like and SVP-like proteins jointly control growth and distinct developmental processes}, school = {Universit{\"a}t Potsdam}, pages = {x, 138}, year = {2023}, abstract = {Based on worldwide consumption, Solanum tuberosum L. (potato) is the most important non-grain food crop. Potato has two ways of stable propagation: sexually via flowering and vegetatively via tuberization. Remarkably, these two developmental processes are controlled by similar molecular regulators and mechanisms. Given that FLC and SVP genes act as key flowering regulators in the model species Arabidopsis and in various other crop species, this study aimed at identifying FLC and SVP homologs in potato and investigating their roles in the regulation of plant development, with a particular focus on flowering and tuberization. Our analysis demonstrated that there are five FLC-like and three SVP like proteins encoded in the potato genome. The expression profiles of StFLCs and StSVPs throughout potato development and the detected interactions between their proteins indicate tissue specificity of the individual genes and distinct roles of a variety of putative protein complexes. In particular, we discovered that StFLC-D, as well as StFLC-B, StSVP-A, and StSVP-B play a complex role in the regulation of flowering time, as not only increased but also decreased levels of their transcripts promote earlier flowering. Most importantly, StFLC-D has a marked impact on tuberization under non-inductive conditions and susceptibility to temperature-induced tuber malformation, also known as second growth. Plants with decreased levels of StFLC-D demonstrated a strong ability to produce tubers under long days and appeared to be insensitive to temperature-induced second growth. Lastly, our data also suggests that StFLCs and StSVPs may be involved in the nitrogen-dependent regulation of potato development. Taken together, this study highlights the functional importance of StFLC and StSVP genes in the regulation of distinct developmental processes in potato.}, language = {en} } @phdthesis{Parry2023, author = {Parry, Victor}, title = {From individual to community level: Assessing swimming movement, dispersal and fitness of zooplankton}, doi = {10.25932/publishup-59769}, url = {http://nbn-resolving.de/urn:nbn:de:kobv:517-opus4-597697}, school = {Universit{\"a}t Potsdam}, pages = {ix, 118}, year = {2023}, abstract = {Movement is a mechanism that shapes biodiversity patterns across spatialtemporal scales. Thereby, the movement process affects species interactions, population dynamics and community composition. In this thesis, I disentangled the effects of movement on the biodiversity of zooplankton ranging from the individual to the community level. On the individual movement level, I used video-based analysis to explore the implication of movement behavior on preypredator interactions. My results showed that swimming behavior was of great importance as it determined their survival in the face of predation. The findings also additionally highlighted the relevance of the defense status/morphology of prey, as it not only affected the prey-predator relationship by the defense itself but also by plastic movement behavior. On the community movement level, I used a field mesocosm experiment to explore the role of dispersal (time i.e., from the egg bank into the water body and space i.e., between water bodies) in shaping zooplankton metacommunities. My results revealed that priority effects and taxon-specific dispersal limitation influenced community composition. Additionally, different modes of dispersal also generated distinct community structures. The egg bank and biotic vectors (i.e. mobile links) played significant roles in the colonization of newly available habitat patches. One crucial aspect that influences zooplankton species after arrival in new habitats is the local environmental conditions. By using common garden experiments, I assessed the performance of zooplankton communities in their home vs away environments in a group of ponds embedded within an agricultural landscape. I identified environmental filtering as a driving factor as zooplankton communities from individual ponds developed differently in their home and away environments. On the individual species level, there was no consistent indication of local adaptation. For some species, I found a higher abundance/fitness in their home environment, but for others, the opposite was the case, and some cases were indifferent. Overall, the thesis highlights the links between movement and biodiversity patterns, ranging from the individual active movement to the community level.}, language = {en} } @phdthesis{Pramanik2023, author = {Pramanik, Shreya}, title = {Protein reconstitution in giant vesicles}, doi = {10.25932/publishup-61278}, url = {http://nbn-resolving.de/urn:nbn:de:kobv:517-opus4-612781}, school = {Universit{\"a}t Potsdam}, pages = {VIII, 132}, year = {2023}, abstract = {Das Leben auf der Erde ist vielf{\"a}ltig und reicht von einzelligen Organismen bis hin zu mehrzelligen Lebewesen wie dem Menschen. Obwohl es Theorien dar{\"u}ber gibt, wie sich diese Organismen entwickelt haben k{\"o}nnten, verstehen wir nur wenig dar{\"u}ber, wie "Leben" aus Molek{\"u}len entstanden ist. Die synthetische Bottom-up-Biologie zielt darauf ab, minimale Zellen zu schaffen, indem sie verschiedene Module wie Kompartimentierung, Wachstum, Teilung und zellul{\"a}re Kommunikation kombiniert. Alle lebenden Zellen haben eine Membran, die sie von dem sie umgebenden w{\"a}ssrigen Medium trennt und sie sch{\"u}tzt. Dar{\"u}ber hinaus haben alle eukaryotischen Zellen Organellen, die von intrazellul{\"a}ren Membranen umschlossen sind. Jede Zellmembran besteht haupts{\"a}chlich aus einer Lipiddoppelschicht mit Membranproteinen. Lipide sind amphiphile Molek{\"u}le, die molekulare Doppelschichten aus zwei Lipid-Monoschichten oder Bl{\"a}ttchen bilden. Die hydrophoben Ketten der Lipide sind einander zugewandt, w{\"a}hrend ihre hydrophilen Kopfgruppen die Grenzfl{\"a}chen zur w{\"a}ssrigen Umgebung bilden. Riesenvesikel sind Modellmembransysteme, die Kompartimente mit einer Gr{\"o}ße von mehreren Mikrometern bilden und von einer einzigen Lipiddoppelschicht umgeben sind. Die Gr{\"o}ße der Riesenvesikel ist mit der Gr{\"o}ße von Zellen vergleichbar und macht sie zu guten Membranmodellen, die mit einem Lichtmikroskop untersucht werden k{\"o}nnen. Allerdings fehlen den Riesenvesikelmembranen nach der ersten Pr{\"a}paration Membranproteine, die in weiteren Pr{\"a}parationsschritten in diese Membranen eingebaut werden m{\"u}ssen. Je nach Protein kann es entweder {\"u}ber Ankerlipide an eines der Membranbl{\"a}ttchen gebunden oder {\"u}ber seine Transmembrandom{\"a}nen in die Lipiddoppelschicht eingebaut werden. Diese Arbeit befasst sich mit der Herstellung von Riesenvesikeln und der Rekonstitution von Proteinen in diesen Vesikeln. Außerdem wird ein mikrofluidischer Chip entworfen, der in verschiedenen Experimenten verwendet werden kann. Die Ergebnisse dieser Arbeit werden anderen Forschern helfen, die Protokolle f{\"u}r die Herstellung von GUVs zu verstehen, Proteine in GUVs zu rekonstituieren und Experimente mit dem mikrofluidischen Chip durchzuf{\"u}hren. Auf diese Weise wird die vorliegende Arbeit f{\"u}r das langfristige Ziel von Nutzen sein, die verschiedenen Module der synthetischen Biologie zu kombinieren, um eine Minimalzelle zu schaffen.}, language = {en} } @phdthesis{MendesFerreira2023, author = {Mendes Ferreira, Clara}, title = {Indirect, tri-trophic effects of fear on biodiversity}, doi = {10.25932/publishup-61102}, url = {http://nbn-resolving.de/urn:nbn:de:kobv:517-opus4-611020}, school = {Universit{\"a}t Potsdam}, pages = {119}, year = {2023}, abstract = {Predator-forager interactions are a major factor in evolutionary adaptation of many species, as predators need to gain energy by consuming prey species, and foragers needs to avoid the worst fate of mortality while still consuming resources for energetic gains. In this evolutionary arms race, the foragers have constantly evolved anti-predator behaviours (e.g. foraging activity changes). To describe all these complex changes, researchers developed the framework of the landscape of fear, that is, the spatio-temporal variation of perceived predation risk. This concept simplifies all the involved ecological processes into one framework, by integrating animal biology and distribution with habitat characteristics. Researchers can then evaluate the perception of predation risk in prey species, what are the behavioural responses of the prey and, therefore, understand the cascading effects of landscapes of fear at the resource levels (tri-trophic effects). Although tri-trophic effects are well studied at the predator-prey interaction level, little is known on how the forager-resource interactions are part of the overall cascading effects of landscapes of fear, despite the changes of forager feeding behaviour - that occur with perceived predation risk - affecting directly the level of the resources. This thesis aimed to evaluate the cascading effects of the landscape of fear on biodiversity of resources, and how the feeding behaviour and movement of foragers shaped the final resource species composition (potential coexistence mechanisms). We studied the changes caused by landscapes of fear on wild and captive rodent communities and evaluated: the cascading effects of different landscapes of fear on a tri-trophic system (I), the effects of fear on a forager's movement patterns and dietary preferences (II) and cascading effects of different types of predation risk (terrestrial versus avian, III). In Chapter I, we applied a novel measure to evaluate the cascading effects of fear at the level of resources, by quantifying the diversity of resources left after the foragers gave-up on foraging (diversity at the giving-up density). We tested the measure at different spatial levels (local and regional) and observed that with decreased perceived predation risk, the density and biodiversity of resources also decreased. Foragers left a very dissimilar community of resources based on perceived risk and resources functional traits, and therefore acted as an equalising mechanism. In Chapter II, we wanted to understand further the decision-making processes of rodents in different landscapes of fear, namely, in which resource species rodents decided to forage on (based on three functional traits: size, nutrients and shape) and how they moved depending on perceived predation risk. In safe landscapes, individuals increased their feeding activity and movements and despite the increased costs, they visited more often patches that were further away from their central-place. Despite a preference for the bigger resources regardless of risk, when perceived predation risk was low, individuals changed their preference to fat-rich resources. In Chapter III, we evaluated the cascading effects of two different types of predation risk in rodents: terrestrial (raccoon) versus avian predation risk. Raccoon presence or absence did not alter the rodents feeding behaviour in different landscapes of fear. Rodent's showed risk avoidance behaviours towards avian predators (spatial risk avoidance), but not towards raccoons (lack of temporal risk avoidance). By analysing the effects of fear in tri-trophic systems, we were able to deepen the knowledge of how non-consumptive effects of predators affect the behaviour of foragers, and quantitatively measure the cascading effects at the level of resources with a novel measure. Foragers are at the core of the ecological processes and responses to the landscape of fear, acting as variable coexistence agents for resource species depending on perceived predation risk. This newly found measures and knowledge can be applied to more trophic chains, and inform researchers on biodiversity patterns originating from landscapes of fear.}, language = {en} } @phdthesis{BysaniKondagari2023, author = {Bysani Kondagari, Viswanada Reddy}, title = {Engineering and evolution of saccharomyces cerevisiae for synthetic formatotrophic growth via the reductive glycine pathway}, doi = {10.25932/publishup-58222}, url = {http://nbn-resolving.de/urn:nbn:de:kobv:517-opus4-582222}, school = {Universit{\"a}t Potsdam}, pages = {124}, year = {2023}, abstract = {Increasing demand for food, healthcare, and transportation arising from the growing world population is accompanied by and driving global warming challenges due to the rise of the atmospheric CO2 concentration. Industrialization for human needs has been increasingly releasing CO2 into the atmosphere for the last century or more. In recent years, the possibility of recycling CO2 to stabilize the atmospheric CO2 concentration and combat rising temperatures has gained attention. Thus, using CO2 as the feedstock to address future world demands is the ultimate solution while controlling the rapid climate change. Valorizing CO2 to produce activated and stable one-carbon feedstocks like formate and methanol and further upgrading them to industrial microbial processes to replace unsustainable feedstocks would be crucial for a future biobased circular economy. However, not all microbes can grow on formate as a feedstock, and those microbes that can grow are not well established for industrial processes. S. cerevisiae is one of the industrially well-established microbes, and it is a significant contributor to bioprocess industries. However, it cannot grow on formate as a sole carbon and energy source. Thus, engineering S. cerevisiae to grow on formate could potentially pave the way to sustainable biomass and value-added chemicals production. The Reductive Glycine Pathway (RGP), designed as the aerobic twin of the anaerobic Reductive Acetyl-CoA pathway, is an efficient formate and CO2 assimilation pathway. The RGP comprises of the glycine synthesis module (Mis1p, Gcv1p, Gcv2p, Gcv3p, and Lpd1p), the glycine to serine conversion module (Shmtp), the pyruvate synthesis module (Cha1p), and the energy supply module (Fdh1p). The RGP requires formate and elevated CO2 levels to operate the glycine synthesis module. In this study, I established the RGP in the yeast system using growth-coupled selection strategies to achieve formate and CO2-dependent biomass formation in aerobic conditions. Firstly, I constructed serine biosensor strains by disrupting the native serine and glycine biosynthesis routes in the prototrophic S288c and FL100 yeast strains and insulated serine, glycine, and one-carbon metabolism from the central metabolic network. These strains cannot grow on glucose as the sole carbon source but require the supply of serine or glycine to complement the engineered auxotrophies. Using growth as a readout, I employed these strains as selection hosts to establish the RGP. Initially, to achieve this, I engineered different serine-hydroxymethyltransferases in the genome of serine biosensor strains for efficient glycine to serine conversion. Then, I implemented the glycine synthesis module of the RGP in these strains for the glycine and serine synthesis from formate and CO2. I successfully conducted Adaptive Laboratory Evolution (ALE) using these strains, which yielded a strain capable of glycine and serine biosynthesis from formate and CO2. Significant growth improvements from 0.0041 h-1 to 0.03695 h-1 were observed during ALE. To validate glycine and serine synthesis, I conducted carbon tracing experiments with 13C formate and 13CO2, confirming that more than 90\% of glycine and serine biosynthesis in the evolved strains occurs via the RGP. Interestingly, labeling data also revealed that 10-15\% of alanine was labelled, indicating pyruvate synthesis from the formate-derived serine using native serine deaminase (Cha1p) activity. Thus, RGP contributes to a small pyruvate pool which is converted to alanine without any selection pressure for pyruvate synthesis from formate. Hence, this data confirms the activity of all three modules of RGP even in the presence of glucose. Further, ALE in glucose limiting conditions did not improve pyruvate flux via the RGP. Growth characterization of these strains showed that the best growth rates were achieved in formate concentrations between 25 mM to 300 mM. Optimum growth required 5\% CO2, and dropped when the CO2 concentration was reduced from 5\% to 2.5\%. Whole-genome sequencing of these evolved strains revealed mutations in genes that encode Gdh1p, Pet9p, and Idh1p. These enzymes might influence intracellular NADPH, ATP, and NADH levels, indicating adjustment to meet the energy demand of the RGP. I reverse-engineered the GDH1 truncation mutation on unevolved serine biosensor strains and reproduced formate dependent growth. To elucidate the effect of the GDH1 mutation on formate assimilation, I reintroduced this mutation in the S288c strain and conducted carbon-tracing experiments to compared formate assimilation between WT and ∆gdh1 mutant strains. Comparatively, enhanced formate assimilation was recorded in the ∆gdh1 mutant strain. Although the 13C carbon tracing experiments confirmed the activity of all three modules of the RGP, the overall pyruvate flux via the RGP might be limited by the supply of reducing power. Hence, in a different approach, I overexpressed the formate dehydrogenase (Fdh1p) for energy supply and serine deaminase (Cha1p) for active pyruvate synthesis in the S288c parental strain and established growth on formate and serine without glucose in the medium. Further reengineering and evolution of this strain with a consistent energy, and formate-derived serine supply for pyruvate synthesis, is essential to achieve complete formatotrophic growth in the yeast system.}, language = {en} } @phdthesis{Carrasco2023, author = {Carrasco, Tomas}, title = {Genome structure analysis and patterns of transposable elements evolution in the slow-evolving Testudines clade}, doi = {10.25932/publishup-60657}, url = {http://nbn-resolving.de/urn:nbn:de:kobv:517-opus4-606577}, school = {Universit{\"a}t Potsdam}, pages = {144}, year = {2023}, abstract = {Transposable elements (TEs) are loci that can replicate and multiply within the genome of their host. Within the host, TEs through transposition are responsible for variation on genomic architecture and gene regulation across all vertebrates. Genome assemblies have increased in numbers in recent years. However, to explore in deep the variations within different genomes, such as SNPs (single nucleotide polymorphism), INDELs (Insertion-deletion), satellites and transposable elements, we need high-quality genomes. Studies of molecular markers in the past 10 years have limitations to correlate with biological differences because molecular markers rely on the accuracy of the genomic resources. This has generated that a substantial part of the studies of TE in recent years have been on high quality genomic resources such as Drosophila, zebrafinch and maize. As testudine have a slow mutation rate lower only to crocodilians, with more than 300 species, adapted to different environments all across the globe, the testudine clade can help us to study variation. Here we propose Testudines as a clade to study variation and the abundance of TE on different species that diverged a long time ago. We investigated the genomic diversity of sea turtles, identifying key genomic regions associated to gene family duplication, specific expansion of particular TE families for Dermochelyidae and that are important for phenotypic differentiation, the impact of environmental changes on their populations, and the dynamics of TEs within different lineages. In chapter 1, we identify that despite high levels of genome synteny within sea turtles, we identified that regions of reduced collinearity and microchromosomes showed higher concentrations of multicopy gene families, as well as genetic distances between species, indicating their potential importance as sources of variation underlying phenotypic differentiation. We found that differences in the ecological niches occupied by leatherback and green turtles have led to contrasting evolutionary paths for their olfactory receptor genes. We identified in leatherback turtles a long-term low population size. Nonetheless, we identify no correlation between the regions of reduced collinearity with abundance of TEs or an accumulation of a particular TE group. In chapter 2, we identified that sea turtle genomes contain a significant proportion of TEs, with differences in TE abundance between species, and the discovery of a recent expansion of Penelope-like elements (PLEs) in the highly conserved sea turtle genome provides new insights into the dynamics of TEs within Testudines. In chapter 3, we compared the proportion of TE across the Testudine clade, and we identified that the proportion of transposable elements within the clade is stable, regardless of the quality of the assemblies. However, we identified that the proportion of TEs orders has correlation with genome quality depending of their expanded abundancy. For retrotransposon, a highly abundant element for this clade, we identify no correlation. However, for DNA elements a rarer element on this clade, correlate with the quality of the assemblies. Here we confirm that high-quality genomes are fundamental for the study of transposable element evolution and the conservation within the clade. The detection and abundance of specific orders of TEs are influenced by the quality of the genomes. We identified that a reduction in the population size on D. coriacea had left signals of long-term low population sizes on their genomes. On the same note we identified an expansion of TE on D. coriacea, not present in any other member of the available genomes of Testudines, strongly suggesting that it is a response of deregulation of TE on their genomes as consequences of the low population sizes. Here we have identified important genomic regions and gene families for phenotypic differentiation and highlighted the impact of environmental changes on the populations of sea turtles. We stated that accurate classification and analysis of TE families are important and require high-quality genome assemblies. Using TE analysis we manage to identify differences in highly syntenic species. These findings have significant implications for conservation and provide a foundation for further research into genome evolution and gene function in turtles and other vertebrates. Overall, this study contributes to our understanding of evolutionary change and adaptation mechanisms.}, language = {en} } @phdthesis{Goethel2023, author = {G{\"o}thel, Markus}, title = {Entwicklung eines Verfahrens zur Generierung von spezifischen monoklonalen Antik{\"o}rpern gegen Mikroorganismen basierend auf in silico Epitopanalysen}, doi = {10.25932/publishup-58801}, url = {http://nbn-resolving.de/urn:nbn:de:kobv:517-opus4-588017}, school = {Universit{\"a}t Potsdam}, pages = {XVI, 113}, year = {2023}, abstract = {Monoklonale Antik{\"o}rper (mAK) sind eines der wichtigsten Biomolek{\"u}le f{\"u}r die Umweltanalytik und die medizinische Diagnostik. F{\"u}r die Detektion von Mikroorganismen bilden sie die Grundlage f{\"u}r ein schnelles und pr{\"a}zises Testverfahren. Bis heute gibt es, aufgrund des hohen zeitlichen und materiellen Aufwandes und der unspezifischen Immunisierungsstrategien, nur wenige mAK, die spezifisch Mikroorganismen erkennen. Zu diesem Zweck sollte ein anwendbares Verfahren f{\"u}r die Generierung von mAK gegen Mikroorganismen entwickelt werden, welches anhand von Escherichia coli O157:H7 und Legionella pneumophila validiert wurde. In dieser Dissertation konnten neue Oberfl{\"a}chenstrukturen auf den Mikroorganismen mittels vergleichender Genomanalysen und in silico Epitopanalysen identifiziert werden. Diese wurden in das Virush{\"u}llprotein VP1 integriert und f{\"u}r eine gezielte Immunisierungsstrategie verwendet. F{\"u}r die Bestimmung antigenspezifischer antik{\"o}rperproduzierender Hybridome wurde ein Immunf{\"a}rbeprotokoll entwickelt und etabliert, um die Hybridome im Durchflusszytometer zu sortieren. In der vorliegenden Studie konnten f{\"u}r E. coli O157:H7 insgesamt 53 potenzielle Proteinkandidaten und f{\"u}r L. pneumophila 38 Proteine mithilfe der bioinformatischen Analyse identifiziert werden. F{\"u}nf verschiedene potenzielle Epitope wurden f{\"u}r E. coli O157:H7 und drei verschiedenen f{\"u}r L. pneumophila ausgew{\"a}hlt und f{\"u}r die Immunisierung mit chim{\"a}ren VP1 verwendet. Alle Immunseren zeigten eine antigenspezifische Immunantwort. Aus den nachfolgend generierten Hybridomzellen konnten mehrere Antik{\"o}rperkandidaten gewonnen werden, welche in Charakterisierungsstudien eine starke Bindung zu E. coli O157:H7 bzw. L. pneumophila vorwiesen. Kreuzreaktivit{\"a}ten zu anderen relevanten Mikroorganismen konnten keine bzw. nur in geringem Maße festgestellt werden. Folglich konnte der hier beschriebene interdisziplin{\"a}re Ansatz zur Generierung spezifischer mAK gegen Mikroorganismen nachweislich spezifische mAK hervorbringen und ist als hocheffizienter Arbeitsablauf f{\"u}r die Herstellung von Antik{\"o}rpern gegen Mikroorganismen einsetzbar.}, language = {de} } @misc{MarggrafLindeckeVoigtetal.2023, author = {Marggraf, Lara Christin and Lindecke, Oliver and Voigt, Christian C. and Pētersons, Gunārs and Voigt-Heucke, Silke Luise}, title = {Nathusius' bats, Pipistrellus nathusii, bypass mating opportunities of their own species, but respond to foraging heterospecifics on migratory transit flights}, series = {Zweitver{\"o}ffentlichungen der Universit{\"a}t Potsdam : Mathematisch-Naturwissenschaftliche Reihe}, journal = {Zweitver{\"o}ffentlichungen der Universit{\"a}t Potsdam : Mathematisch-Naturwissenschaftliche Reihe}, number = {1306}, issn = {1866-8372}, doi = {10.25932/publishup-57957}, url = {http://nbn-resolving.de/urn:nbn:de:kobv:517-opus4-579574}, pages = {10}, year = {2023}, abstract = {In late summer, migratory bats of the temperate zone face the challenge of accomplishing two energy-demanding tasks almost at the same time: migration and mating. Both require information and involve search efforts, such as localizing prey or finding potential mates. In non-migrating bat species, playback studies showed that listening to vocalizations of other bats, both con-and heterospecifics, may help a recipient bat to find foraging patches and mating sites. However, we are still unaware of the degree to which migrating bats depend on con-or heterospecific vocalizations for identifying potential feeding or mating opportunities during nightly transit flights. Here, we investigated the vocal responses of Nathusius' pipistrelle bats, Pipistrellus nathusii, to simulated feeding and courtship aggregations at a coastal migration corridor. We presented migrating bats either feeding buzzes or courtship calls of their own or a heterospecific migratory species, the common noctule, Nyctalus noctula. We expected that during migratory transit flights, simulated feeding opportunities would be particularly attractive to bats, as well as simulated mating opportunities which may indicate suitable roosts for a stopover. However, we found that when compared to the natural silence of both pre-and post-playback phases, bats called indifferently during the playback of conspecific feeding sounds, whereas P. nathusii echolocation call activity increased during simulated feeding of N. noctula. In contrast, the call activity of P. nathusii decreased during the playback of conspecific courtship calls, while no response could be detected when heterospecific call types were broadcasted. Our results suggest that while on migratory transits, P. nathusii circumnavigate conspecific mating aggregations, possibly to save time or to reduce the risks associated with social interactions where aggression due to territoriality might be expected. This avoidance behavior could be a result of optimization strategies by P. nathusii when performing long-distance migratory flights, and it could also explain the lack of a response to simulated conspecific feeding. However, the observed increase of activity in response to simulated feeding of N. noctula, suggests that P. nathusii individuals may be eavesdropping on other aerial hawking insectivorous species during migration, especially if these occupy a slightly different foraging niche.}, language = {en} } @misc{OgunkolaGuiraudieCaprazFeronetal.2023, author = {Ogunkola, Moses Olalekan and Guiraudie-Capraz, Gaelle and F{\´e}ron, Fran{\c{c}}ois and Leimk{\"u}hler, Silke}, title = {The Human Mercaptopyruvate Sulfurtransferase TUM1 Is Involved in Moco Biosynthesis, Cytosolic tRNA Thiolation and Cellular Bioenergetics in Human Embryonic Kidney Cells}, series = {Zweitver{\"o}ffentlichungen der Universit{\"a}t Potsdam : Mathematisch-Naturwissenschaftliche Reihe}, journal = {Zweitver{\"o}ffentlichungen der Universit{\"a}t Potsdam : Mathematisch-Naturwissenschaftliche Reihe}, number = {1307}, issn = {1866-8372}, doi = {10.25932/publishup-57958}, url = {http://nbn-resolving.de/urn:nbn:de:kobv:517-opus4-579580}, pages = {23}, year = {2023}, abstract = {Sulfur is an important element that is incorporated into many biomolecules in humans. The incorporation and transfer of sulfur into biomolecules is, however, facilitated by a series of different sulfurtransferases. Among these sulfurtransferases is the human mercaptopyruvate sulfurtransferase (MPST) also designated as tRNA thiouridine modification protein (TUM1). The role of the human TUM1 protein has been suggested in a wide range of physiological processes in the cell among which are but not limited to involvement in Molybdenum cofactor (Moco) biosynthesis, cytosolic tRNA thiolation and generation of H2S as signaling molecule both in mitochondria and the cytosol. Previous interaction studies showed that TUM1 interacts with the L-cysteine desulfurase NFS1 and the Molybdenum cofactor biosynthesis protein 3 (MOCS3). Here, we show the roles of TUM1 in human cells using CRISPR/Cas9 genetically modified Human Embryonic Kidney cells. Here, we show that TUM1 is involved in the sulfur transfer for Molybdenum cofactor synthesis and tRNA thiomodification by spectrophotometric measurement of the activity of sulfite oxidase and liquid chromatography quantification of the level of sulfur-modified tRNA. Further, we show that TUM1 has a role in hydrogen sulfide production and cellular bioenergetics.}, language = {en} } @phdthesis{Jiang2023, author = {Jiang, Li}, title = {Analysis of the role of Heat shock factors and Mediator subunits in heat stress memory in Arabidopsis thaliana}, school = {Universit{\"a}t Potsdam}, pages = {194}, year = {2023}, abstract = {In nature, plants often encounter biotic and abiotic stresses, which can cause reduced crop yield and quality, and threaten the nutrition of a growing human population. As heat stress (HS) is one of the main abiotic stresses, and is projected to increase due to global warming, it is necessary to better understand how plants respond and survive under HS. In Arabidopsis thaliana, plants can survive under severe HS if primed by a non-lethal HS, a process called acquisition of thermotolerance. This primed stated can be maintained for several days, and the ability of plants to maintain the primed state is called maintenance of acquired thermotolerance (mATT) or HS memory. According to current research, two Heat shock factors (HSFs) HSFA2 and HSFA3 are known to account for the majority of mATT capability, and there are other HSFs e.g. HSFA1b and HSFA6b in HSF complexes containing HSFA2 and/or HSFA3, however, the roles of these HSFs in HS memory is not clearly understood. Moreover, the mechanism of these HSFs in regulating HS memory is unclear, whether transcriptional machinery e.g. the Mediator complex contributes to transcriptional memory. This work investigates the role of HSFs and Mediator subunits in HS memory in A. thaliana. For the role of HSFs, the interaction between HSFA1b and HSFA2 during HS memory phase was confirmed by in vivo co- immunoprecipitation (Co-IP). HSFA1b, HSFA2, HSFA3 and HSFA6b targeted HS memory-related genes according to DNA affinity purification sequencing (DAP-seq) data, and targets of HSFA1b were confirmed in vivo by chromatin immunoprecipitation qPCR (ChIP-qPCR). The mutant of hsfa6b showed an HS memory deficiency phenotype in mATT survival assay. These data confirmed the role for HSFA2 and HSFA3 in HS memory, and suggest that HSFA1b and HSFA6b also function in HS memory. The Mediator complex functions as an RNA Polymerase II (RNA Pol II) co-regulator, and includes Head, Middle, Tail and Kinase modules. Both MED23 and MED32 belong to the Tail module, and they have a positive role in HS memory. MED23 interacted with HSFA3, as determined by yeast two hybrid (Y2H) and in vivo Co-IP assays. The med23 mutant showed a decreased HS memory phenotype, reduced expression of Type I (sustained expression) memory genes following HS, and reduced accumulation of the memory-associated Tri-methylation of histone H3 lysine 4 (H3K4me3)histone modification at HS memory-related gene loci after HS. MED23 was recruited to HS-inducible memory and non-memory genes after HS, as determined by ChIP-qPCR. The med32 mutant showed a reduced HS memory phenotype, decreased expression of Type I and Type II (hyper-induction) memory genes, and lower accumulation of H3K4me3 at memory gene lociafter HS. However, MED32 did not show interaction with any tested HSF in Y2H or in vivo Co-IP. MED32 regulated the recruitment of RNA Pol II at HS-inducible genes after HS, but was not itself recruited to HS memory genes after HS. These results provided more evidence that the Mediator subunits MED23 and MED32 regulate HS memory on transcriptional and epigenetic levels. In general, this work provides a better insight into the molecular mechanism of how HSFs and Mediator subunits regulate HS memory in plants and will provide new perspectives to breed crops with improved thermotolerance.}, language = {en} } @phdthesis{Agarwal2023, author = {Agarwal, Pallavi}, title = {Functional characterization of ROS-responsive genes, ANAC085 and ATR7, in Arabidopsis thaliana}, school = {Universit{\"a}t Potsdam}, pages = {XVII, 169}, year = {2023}, language = {en} } @phdthesis{Rasul2023, author = {Rasul, Fiaz}, title = {Biostimulant SuperFifty based molecular priming to increase plant strength and stress tolerance}, year = {2023}, language = {en} } @phdthesis{Mariette2023, author = {Mariette, Alban}, title = {Building a wall: Developing small molecule biosensors to visualize cell wall biosynthesis and untangling mechanismus underlying nucleotide sugar transport}, school = {Universit{\"a}t Potsdam}, pages = {249}, year = {2023}, language = {en} } @phdthesis{Kiemel2023, author = {Kiemel, Katrin}, title = {Zooplankton adaptations and community dynamics in space and time}, school = {Universit{\"a}t Potsdam}, year = {2023}, abstract = {In times of ongoing biodiversity loss, understanding how communities are structured and what mechanisms and local adaptations underlie the patterns we observe in nature is crucial for predicting how future ecological and anthropogenic changes might affect local and regional biodiversity. Aquatic zooplankton are a group of primary consumers that represent a critical link in the food chain, providing nutrients for the entire food web. Thus, understanding the adaptability and structure of zooplankton communities is essential. In this work, the genetic basis for the different temperature adaptations of two seasonally shifted (i.e., temperature-dependent) occurring freshwater rotifers of a formerly cryptic species complex (Brachionus calyciflorus) was investigated to understand the overall genetic diversity and evolutionary scenario for putative adaptations to different temperature regimes. Furthermore, this work aimed to clarify to what extent the different temperature adaptations may represent a niche partitioning process thus enabling co-existence. The findings were then embedded in a metacommunity context to understand how zooplankton communities assemble in a kettle hole metacommunity located in the northeastern German "Uckermark" and which underlying processes contribute to the biodiversity patterns we observe. Using a combined approach of newly generated mitochondrial resources (genomes/cds) and the analysis of a candidate gene (Heat Shock Protein 40kDa) for temperature adaptation, I showed that the global representatives of B. calyciflorus s.s.. are genetically more similar than B. fernandoi (average pairwise nucleotide diversity: 0.079 intraspecific vs. 0.257 interspecific) indicating that both species carry different standing genetic variation. In addition to differential expression in the thermotolerant B. calyciflorus s.s. and thermosensitive B. fernandoi, the HSP 40kDa also showed structural variation with eleven fixed and six positively selected sites, some of which are located in functional areas of the protein. The estimated divergence time of ~ 25-29 Myr combined with the fixed sites and a prevalence of ancestral amino acids in B. calyciflorus s.s. indicate that B. calyciflorus s.s. remained in the ancestral niche, while B. fernandoi partitioned into a new niche. The comparison of mitochondrial and nuclear markers (HPS 40kDa, ITS1, COI) revealed a hybridisation event between the two species. However, as hybridisation between the two species is rare, it can be concluded that the temporally isolated niches (i.e., seasonal-shifted occurrence) they inhabit based on their different temperature preferences most likely represent a pre-zygotic isolation mechanism that allows sympatric occurrence while maintaining species boundaries. To determine the processes underlying zooplankton community assembly, a zooplankton metacommunity comprising 24 kettle holes was sampled over a two-year period. Active (i.e., water samples) and dormant communities (i.e., dormant eggs hatched from sediment) were identified using a two-fragment DNA metabarcoding approach (COI and 18S). Species richness and diversity as well as community composition were analysed considering spatial, temporal and environmental parameters. The analysis revealed that environmental filtering based on parameters such as pH, size and location of the habitat patch (i.e., kettle hole) and surrounding field crops largely determined zooplankton community composition (explained variance: Bray-Curtis dissimilarities: 10.5\%; Jaccard dissimilarities: 12.9\%), indicating that adaptation to a particular habitat is a key feature of zooplankton species in this system. While the spatial configuration of the kettle holes played a minor role (explained variance: Bray-Curtis dissimilarities: 2.8\% and Jaccard dissimilarities: 5.5\%), the individual kettle hole sites had a significant influence on the community composition. This suggests monopolisation/priority effects (i.e., dormant communities) of certain species in individual kettle holes. As environmental filtering is the dominating process structuring zooplankton communities, this system could be significantly influenced by future land-use change, pollution and climate change.}, language = {en} } @phdthesis{Pruefer2023, author = {Pr{\"u}fer, Mareike}, title = {Charakterisierung und wechselfeldgest{\"u}tzte Herstellung von Enzym-Nanoarrays}, doi = {10.25932/publishup-61232}, url = {http://nbn-resolving.de/urn:nbn:de:kobv:517-opus4-612329}, school = {Universit{\"a}t Potsdam}, pages = {104}, year = {2023}, abstract = {Dielektrophorese ist die Manipulation polarisierbarer Partikel durch inhomogene elektrische Wechselfelder. In dieser Arbeit wurden drei verschiedene Enzyme durch Dielektrophorese immobilisiert und anschließend hinsichtlich ihrer katalytischen Aktivit{\"a}t untersucht: Meerrettichperoxidase, Cholinoxidase aus Alcaligenes sp. und Glucoseoxidase aus Aspergillus niger. Die Immobilisierung erfolgte durch Dielektrophorese auf nano-Elektrodenarrays aus Wolfram-Zylindern mit 500 nm Durchmesser oder aus Titannitrid-Ringen mit 20 nm Breite. Die Immobilisierung der Enzyme konnte fluoreszenzmikroskopisch entweder anhand der intrinsischen Fluoreszenz oder aufgrund einer Fluoreszenzmarkierung vor oder nach der Immobilisierung f{\"u}r alle getesteten Enzyme nachgewiesen werden. Die Messung der Enzymaktivit{\"a}t erfolgte quantitativ durch den direkten oder indirekten Nachweis des gebildeten Produktes oder, im Falle der Cholinoxidase, durch Beobachtung der intrinsischen Fluoreszenz des Cofaktors FAD, die vom Oxidationszustand dieses Enzyms abh{\"a}ngt. F{\"u}r die Meerrettichperoxidase konnte so eine hohe erhaltene Enzymaktivit{\"a}t nach der Immobilisierung nachgewiesen werden. Die Aktivit{\"a}t der permanent immobilisierten Fraktion der Meerrettichperoxidase entsprach bis zu 47 \% der h{\"o}chstm{\"o}glichen Aktivit{\"a}t einer Monolage dieses Enzyms auf den Elektroden des Chips. Diese Aktivit{\"a}t kann als aktive, aber zuf{\"a}llig gegen{\"u}ber der Oberfl{\"a}che ausgerichtete Enzymschicht interpretiert werden. F{\"u}r die permanent immobilisierte Glucoseoxidase wurde nur eine Aktivit{\"a}t entsprechend <1,3 \% der Aktivit{\"a}t einer solchen Enzymschicht detektiert, w{\"a}hrend f{\"u}r die immobilisierte Cholinoxidase gar keine Aktivit{\"a}t nachgewiesen werden konnte. Die Aktivit{\"a}t der durch DEP immobilisierten Enzyme konnte somit quantitativ bestimmt werden. Der Anteil an erhaltener Aktivit{\"a}t h{\"a}ngt dabei stark vom verwendeten Enzym ab.}, language = {de} } @phdthesis{Petrich2023, author = {Petrich, Annett}, title = {Quantitative fluorescence microscopy methods to investigate molecular interactions and dynamics in living cells}, doi = {10.25932/publishup-61180}, url = {http://nbn-resolving.de/urn:nbn:de:kobv:517-opus4-611800}, school = {Universit{\"a}t Potsdam}, pages = {244}, year = {2023}, abstract = {Biomolecules such as proteins and lipids have vital roles in numerous cellular functions, including biomolecule transport, protein functions, cellular homeostasis and biomembrane integrity. Traditional biochemistry methods do not provide precise information about cellular biomolecule distribution and behavior under native environmental conditions since they are not transferable to live cell samples. Consequently, this can lead to inaccuracies in quantifying biomolecule interactions due to potential complexities arising from the heterogeneity of native biomembranes. To overcome these limitations, minimal invasive microscopic techniques, such as fluorescence fluctuation spectroscopy (FFS) in combination with fluorescence proteins (FPs) and fluorescence lipid analogs, have been developed. FFS techniques and membrane property sensors enable the quantification of various parameters, including concentration, dynamics, oligomerization, and interaction of biomolecules in live cell samples. In this work, several FFS approaches and membrane property sensors were implemented and employed to examine biological processes of diverse context. Multi-color scanning fluorescence fluctuation spectroscopy (sFCS) was used the examine protein oligomerization, protein-protein interactions (PPIs) and protein dynamics at the cellular plasma membrane (PM). Additionally, two-color number and brightness (N\&B) analysis was extended with the cross-correlation analysis in order to quantify hetero-interactions of proteins in the PM with very slow motion, which would not accessible with sFCS due strong initial photobleaching. Furthermore, two semi-automatic analysis pipelines were designed: spectral F{\"o}rster resonance energy transfer (FRET) analysis to study changes in membrane charge at the inner leaflet of the PM, and spectral generalized polarization (GP) imaging and spectral phasor analysis to monitor changes in membrane fluidity and order. An important parameter for studying PPIs is molecular brightness, which directly determines oligomerization and can be extracted from FFS data. However, FPs often display complex photophysical transitions, including dark states. Therefore, it is crucial to characterize FPs for their dark-states to ensure reliable oligomerization measurements. In this study, N\&B and sFCS analysis were applied to determine photophysical properties of novel green FPs under different conditions (i.e., excitation power and pH) in living cells. The results showed that the new FPs, mGreenLantern (mGL) and Gamillus, exhibited the highest molecular brightness at the cost of lower photostability. The well-established monomeric enhanced green fluorescent protein (mEGFP) remained the best option to investigate PPIs at lower pH, while mGL was best suited for neutral pH, and Gamillus for high pH. These findings provide guidance for selecting an appropriate FP to quantify PPIs via FFS under different environmental conditions. Next, several biophysical fluorescence microscopy approaches (i.e., sFCS, GP imaging, membrane charge FRET) were employed to monitor changes in lipid-lipid-packing in biomembranes in different biological context. Lipid metabolism in cancer cells is known to support rapid proliferation and metastasis. Therefore, targeting lipid synthesis or membrane integrity holds immense promise as an anticancer strategy. However, the mechanism of action of the novel agent erufosine (EPC3) on membrane stability is not fully under stood. The present work revealed that EPC3 reduces lipid packing and composition as well as increased membrane fluidity and dynamic, hence, modifies lipid-lipid-interaction. These effects on membrane integrity were likely triggered by modulations in lipid metabolism and membrane organization. In the case of influenza A virus (IAV) infection, regulation of lipid metabolism is crucial for multiple steps in IAV replication and is related to the pathogenicity of IAV. Here, it is shown for the first time that IAV infection triggers a local enrichment of negatively charged lipids at the inner leaflet of the PM, which decreases membrane fluidity and dynamic, as well as increases lipid packing at the assembly site in living cells. This suggests that IAV alters lipid-lipid interactions and organization at the PM. Overall, this work highlights the potential of biophysical techniques as a screening platform for studying membrane properties in living cells at the single-cell level. Finally, this study addressed remaining questions about the early stage of IAV assembly. The recruitment of matrix protein 1 (M1) and its interaction with other viral surface proteins, hemagglutinin (HA), neuraminidase (NA), and matrix protein 2 (M2), has been a subject of debate due to conflicting results. In this study, different FFS approaches were performed in transfected cells to investigate interactions between IAV proteins themselves and host factors at the PM. FFS measurements revealed that M2 interacts strongly with M1, leading to the translocation of M1 to the PM. This interaction likely took place along the non-canonical pathway, as evidenced by the detection of an interaction between M2 and the host factor LC3-II, leading to the recruitment of LC3-II to the PM. Moreover, weaker interaction was observed between HA and membrane-bound M1, and no interaction between NA and M1. Interestingly, higher oligomeric states of M1 were only detectable in infected cells. These results indicate that M2 initiates virion assembly by recruiting M1 to the PM, which may serve as a platform for further interactions with viral proteins and host factors.}, language = {en} } @phdthesis{Stanke2023, author = {Stanke, Sandra}, title = {AC electrokinetic immobilization of influenza viruses and antibodies on nanoelectrode arrays for on-chip immunoassays}, doi = {10.25932/publishup-61716}, url = {http://nbn-resolving.de/urn:nbn:de:kobv:517-opus4-617165}, school = {Universit{\"a}t Potsdam}, pages = {x, 115}, year = {2023}, abstract = {In the present thesis, AC electrokinetic forces, like dielectrophoresis and AC electroosmosis, were demonstrated as a simple and fast method to functionalize the surface of nanoelectrodes with submicrometer sized biological objects. These nanoelectrodes have a cylindrical shape with a diameter of 500 nm arranged in an array of 6256 electrodes. Due to its medical relevance influenza virus as well as anti-influenza antibodies were chosen as a model organism. Common methods to bring antibodies or proteins to biosensor surfaces are complex and time-consuming. In the present work, it was demonstrated that by applying AC electric fields influenza viruses and antibodies can be immobilized onto the nanoelectrodes within seconds without any prior chemical modification of neither the surface nor the immobilized biological object. The distribution of these immobilized objects is not uniform over the entire array, it exhibits a decreasing gradient from the outer row to the inner ones. Different causes for this gradient have been discussed, such as the vortex-shaped fluid motion above the nanoelectrodes generated by, among others, electrothermal fluid flow. It was demonstrated that parts of the accumulated material are permanently immobilized to the electrodes. This is a unique characteristic of the presented system since in the literature the AC electrokinetic immobilization is almost entirely presented as a method just for temporary immobilization. The spatial distribution of the immobilized viral material or the anti-influenza antibodies at the electrodes was observed by either the combination of fluorescence microscopy and deconvolution or by super-resolution microscopy (STED). On-chip immunoassays were performed to examine the suitability of the functionalized electrodes as a potential affinity-based biosensor. Two approaches were pursued: A) the influenza virus as the bio-receptor or B) the influenza virus as the analyte. Different sources of error were eliminated by ELISA and passivation experiments. Hence, the activity of the immobilized object was inspected by incubation with the analyte. This resulted in the successful detection of anti-influenza antibodies by the immobilized viral material. On the other hand, a detection of influenza virus particles by the immobilized anti-influenza antibodies was not possible. The latter might be due to lost activity or wrong orientation of the antibodies. Thus, further examinations on the activity of by AC electric fields immobilized antibodies should follow. When combined with microfluidics and an electrical read-out system, the functionalized chips possess the potential to serve as a rapid, portable, and cost-effective point-of-care (POC) device. This device can be utilized as a basis for diverse applications in diagnosing and treating influenza, as well as various other pathogens.}, language = {en} } @phdthesis{Leins2023, author = {Leins, Johannes A.}, title = {Combining model detail with large scales}, doi = {10.25932/publishup-58283}, url = {http://nbn-resolving.de/urn:nbn:de:kobv:517-opus4-582837}, school = {Universit{\"a}t Potsdam}, pages = {xv, 168}, year = {2023}, abstract = {The global climate crisis is significantly contributing to changing ecosystems, loss of biodiversity and is putting numerous species on the verge of extinction. In principle, many species are able to adapt to changing conditions or shift their habitats to more suitable regions. However, change is progressing faster than some species can adjust, or potential adaptation is blocked and disrupted by direct and indirect human action. Unsustainable anthropogenic land use in particular is one of the driving factors, besides global heating, for these ecologically critical developments. Precisely because land use is anthropogenic, it is also a factor that could be quickly and immediately corrected by human action. In this thesis, I therefore assess the impact of three climate change scenarios of increasing intensity in combination with differently scheduled mowing regimes on the long-term development and dispersal success of insects in Northwest German grasslands. The large marsh grasshopper (LMG, Stethophyma grossum, Linn{\´e} 1758) is used as a species of reference for the analyses. It inhabits wet meadows and marshes and has a limited, yet fairly good ability to disperse. Mowing and climate conditions affect the development and mortality of the LMG differently depending on its life stage. The specifically developed simulation model HiLEG (High-resolution Large Environmental Gradient) serves as a tool for investigating and projecting viability and dispersal success under different climate conditions and land use scenarios. It is a spatially explicit, stage- and cohort-based model that can be individually configured to represent the life cycle and characteristics of terrestrial insect species, as well as high-resolution environmental data and the occurrence of external disturbances. HiLEG is a freely available and adjustable software that can be used to support conservation planning in cultivated grasslands. In the three case studies of this thesis, I explore various aspects related to the structure of simulation models per se, their importance in conservation planning in general, and insights regarding the LMG in particular. It became apparent that the detailed resolution of model processes and components is crucial to project the long-term effect of spatially and temporally confined events. Taking into account conservation measures at the regional level has further proven relevant, especially in light of the climate crisis. I found that the LMG is benefiting from global warming in principle, but continues to be constrained by harmful mowing regimes. Land use measures could, however, be adapted in such a way that they allow the expansion and establishment of the LMG without overly affecting agricultural yields. Overall, simulation models like HiLEG can make an important contribution and add value to conservation planning and policy-making. Properly used, simulation results shed light on aspects that might be overlooked by subjective judgment and the experience of individual stakeholders. Even though it is in the nature of models that they are subject to limitations and only represent fragments of reality, this should not keep stakeholders from using them, as long as these limitations are clearly communicated. Similar to HiLEG, models could further be designed in such a way that not only the parameterization can be adjusted as required, but also the implementation itself can be improved and changed as desired. This openness and flexibility should become more widespread in the development of simulation models.}, language = {en} } @phdthesis{Stuebler2023, author = {St{\"u}bler, Sabine}, title = {Mathematical model of the mucosal immune response to study inflammatory bowel diseases and their treatments}, doi = {10.25932/publishup-61230}, url = {http://nbn-resolving.de/urn:nbn:de:kobv:517-opus4-612301}, school = {Universit{\"a}t Potsdam}, pages = {xiv, 194}, year = {2023}, abstract = {Inflammatory bowel diseases (IBD), characterised by a chronic inflammation of the gut wall, develop as consequence of an overreacting immune response to commensal bacteria, caused by a combination of genetic and environmental conditions. Large inter-individual differences in the outcome of currently available therapies complicate the decision for the best option for an individual patient. Predicting the prospects of therapeutic success for an individual patient is currently only possible to a limited extent; for this, a better understanding of possible differences between responders and non-responders is needed. In this thesis, we have developed a mathematical model describing the most important processes of the gut mucosal immune system on the cellular level. The model is based on literature data, which were on the one hand used (qualitatively) to choose which cell types and processes to incorporate and to derive the model structure, and on the other hand (quantitatively) to derive the parameter values. Using ordinary differential equations, it describes the concentration-time course of neutrophils, macrophages, dendritic cells, T cells and bacteria, each subdivided into different cell types and activation states, in the lamina propria and mesenteric lymph nodes. We evaluate the model by means of simulations of the healthy immune response to salmonella infection and mucosal injury. A virtual population includes IBD patients, which we define through their initially asymptomatic, but after a trigger chronically inflamed gut wall. We demonstrate the model's usefulness in different analyses: (i) The comparison of virtual IBD patients with virtual healthy individuals shows that the disease is elicited by many small or fewer large changes, and allows to make hypotheses about dispositions relevant for development of the disease. (ii) We simulate the effects of different therapeutic targets and make predictions about the therapeutic outcome based on the pre-treatment state. (iii) From the analysis of differences between virtual responders and non-responders, we derive hypotheses about reasons for the inter-individual variability in treatment outcome. (iv) For the example of anti-TNF-alpha therapy, we analyse, which alternative therapies are most promising in case of therapeutic failure, and which therapies are most suited for combination therapies: For drugs also directly targeting the cytokine levels or inhibiting the recruitment of innate immune cells, we predict a low probability of success when used as alternative treatment, but a large gain when used in a combination treatment. For drugs with direct effects on T cells, via modulation of the sphingosine-1-phosphate receptor or inhibition of T cell proliferation, we predict a considerably larger probability of success when used as alternative treatment, but only a small additional gain when used in a combination therapy.}, language = {en} } @phdthesis{CalderonQuinonez2023, author = {Calder{\´o}n Qui{\~n}{\´o}nez, Ana Patricia}, title = {Ecology and conservation of the jaguar (Panthera onca) in Central America}, doi = {10.25932/publishup-61367}, url = {http://nbn-resolving.de/urn:nbn:de:kobv:517-opus4-613671}, school = {Universit{\"a}t Potsdam}, pages = {140}, year = {2023}, abstract = {Conservation of the jaguar relies on holistic and transdisciplinary conservation strategies that integratively safeguard essential, connected habitats, sustain viable populations and their genetic exchange, and foster peaceful human-jaguar coexistence. These strategies define four research priorities to advance jaguar conservation throughout the species' range. In this thesis I provide several relevant ecological and sociological insights into these research priorities, each addressed in a separate chapter. I focus on the effects of anthropogenic landscapes on jaguar habitat use and population gene flow, spatial patterns of jaguar habitat suitability and functional population connectivity, and on innovative governance approaches which can work synergistically to help achieve human-wildlife conviviality. Furthermore, I translate these insights into recommendations for conservation practice by providing tools and suggestions that conservation managers and stakeholders can use to implement local actions but also make broad scale conservation decisions in Central America. In Chapter 2, I model regional habitat use of jaguars, producing spatially-explicit maps for management of key areas of habitat suitability. Using an occupancy model of 13-year-camera-trap occurrence data, I show that human influence has the strongest impact on jaguar habitat use, and that Jaguar Conservation Units are the most important reservoirs of high quality habitat in this region. I build upon these results by zooming in to an area of high habitat suitability loss in Chapter 3, northern Central America. Here I study the drivers of jaguar gene flow and I produce spatially-explicit maps for management of key areas of functional population connectivity in this region. I use microsatellite data and pseudo-optimized multiscale, multivariate resistance surfaces of gene flow to show that jaguar gene flow is influenced by environmental, and even more strongly, by human influence variables; and that the areas of lowest gene flow resistance largely coincide with the location of the Jaguar Conservation Units. Given that human activities significantly impact jaguar habitat use and gene flow, securing viable jaguar populations in anthropogenic landscapes also requires fostering peaceful human-wildlife coexistence. This is a complex challenge that cannot be met without transdisciplinary academic research and cross-sectoral, collaborative governance structures that effectively respond to the multiple challenges of such coexistence. With this in mind, I focus in Chapter 4 on carnivore conservation initiatives that apply transformative governance approaches to enact transformative change towards human-carnivore coexistence. Using the frameworks of transformative biodiversity governance and convivial conservation, I highlight in this chapter concrete pathways, supported by more inclusive, democratic forms of conservation decision-making and participation that promote truly transformative changes towards human-jaguar conviviality.}, language = {en} } @phdthesis{Sureshkumar2023, author = {Sureshkumar, Priyavathi}, title = {Erweiterung der zellbasierten Calcium-Imaging-Methode im eukaryotischen zellfreien Proteinsynthese-System f{\"u}r die transient-receptor-potential (TRP) - Ionenkan{\"a}le}, doi = {10.25932/publishup-61987}, url = {http://nbn-resolving.de/urn:nbn:de:kobv:517-opus4-619872}, school = {Universit{\"a}t Potsdam}, pages = {x, 110}, year = {2023}, abstract = {Die Fluoreszenz-Calcium-Imaging-Methode wird auch heute noch als g{\"a}ngige Methode verwendet, vor allem wegen der geringeren Kosten f{\"u}r das Wirkstoffscreening in der pharmazeutischen Forschung, wobei Ionenkan{\"a}le sowie einige der G-Protein gekoppelte Rezeptoren (GPCRs) die Mehrzahl der Wirkstoffziele ansprechen. Die zellfreie Synthese eukaryotischer Proteine hat nicht die Nachteile, die bei der {\"U}berexpression dieser ionenpermeablen Proteine in Zellen auftreten k{\"o}nnen, wie z. B. Zelltoxizit{\"a}t, geringere Proteinexpression und die Beseitigung der exprimierten Proteine aufgrund ver{\"a}nderter Dom{\"a}nen sowie die zeitaufw{\"a}ndige Pflege von Zelllinien. Die Synthese von Ionenkan{\"a}len in zellfreien Proteinsyntheseplattformen f{\"u}r das k{\"u}nftige Wirkstoffscreening ist noch in der Grundlagenforschung. Obwohl die Fluoreszenz-Calcium-Imaging-Methode in zellbasierten Assays weit verbreitet ist, wurde diese Methode bisher noch nicht in zellfreien Proteinexpressionssystemen verwendet. Insgesamt ist die neue Anwendung der Calcium-Imaging-Methode in eukaryontischen zellfreien Systemen eine Voraussetzung f{\"u}r die schnelle pharmakologische Analyse von Wirkstoffen. Das erste Ziel dieser wissenschaftlichen Arbeit bestand darin, die grundlegenden Prinzipien der Calcium-Imaging-Methode zur Untersuchung von Ionenkan{\"a}len in zellbasierten Systemen zu untersuchen. Hierf{\"u}r wurden zwei Tumorzelllinien des Auges verwendet, und zwar benigne Pterygiumzellen und maligne Aderhautmelanom 92.1 Zellen. In diesen Studien wurde die Interaktion zwischen den nativ {\"u}berexprimierten transient-receptor-potential-Ionenkan{\"a}len (TRPs) wie TRP Vanilliod 1 (TRPV1) (Capsaicinrezeptor) und TRP Melastatin 8 (TRPM8) (Mentholrezeptor) in diesen Tumorzellen nach Zugabe von verschiedenen Medikamenten und Hormonen untersucht. Das zweite Ziel dieser Arbeit war es, den Calcium-Mechanismus von GPCRs in den Zellen zu untersuchen. Zu diesem Zweck wurde Mas, ein GPCR und Angiotensin (1-7) -Hormonrezeptor, aus dem renin-angiotensin-aldosteron-system (RAAS) in der Human Embryonic Kidney-293 (HEK293) Zelllinie {\"u}berexprimiert. In dieser Studie wurden insbesondere die Aktivierung klassischer GPCR-Signalwege wie Phospholipase C und Proteinkinase C durch Angiotensin-(1-7) {\"u}ber Mas und die Beteiligung von TRP-Kan{\"a}len nachgewiesen. Die zellbasierte-Calcium-Imaging-Methode f{\"u}r chemische Calcium-Indikatoren ließ sich aufgrund der Anwesenheit einer großen Menge cytosolischer Carboxylesterasen gut anwenden. Carboxylesterase ist das wichtigste Enzym in der Calcium Imaging Methode, das die Verarbeitung chemischen Calcium-Farbstoffe behandelt. Dieses Enzym fehlt jedoch in Mikrosomen, die als Basismembran f{\"u}r die Integration synthetisierter Ionenkan{\"a}le in eukaryontischen zellfreien Systemen verwendet werden. Das dritte Ziel dieser Forschungsarbeit war die Umsetzung der zellbasierten Calcium-Imaging Methode und der Calcium-Signalwege in zellfreie Systeme. Hier wurde die zellfrei synthetisierte Carboxylesterase in Mikrosomen von Spodoptera frugiperda (Sf21) als praktikables Calcium-Imaging-Werkzeug etabliert, um sowohl native ionenpermeable Proteine als auch zellfrei-synthetisierte Ionenkan{\"a}le zu untersuchen. Die Enzymaktivit{\"a}t der zellfrei-synthetisierten Carboxylesterase in Mikrosomen wurde durch Esterase-Assays und den Calcium-Fluoreszenzfarbstoff Fluo-5N Acetoxymethylester (Fluo-5N AM) Belastungstests nachgewiesen. Das Calcium-Imaging der nativ vorhandenen Ca2+-ATPase des sarkoplasmatischen/endoplasmatischen Retikulums (SERCA) und der Ryanodin-Rezeptoren (RyR) in den Mikrosomen sowie der zell-frei exprimierten TRP-Ionenkan{\"a}le wurden mit dem Fura-5N-AM- Fluoreszenzfarbstoff in mit Carboxylesterase vorsynthetisierten Mikrosomen nachgewiesen. Zusammenfassend l{\"a}sst sich sagen, dass das Prinzip der zellbasierten Calcium-Imaging -Methode vielversprechend an das eukaryotische zellfreie Sf21-System angepasst werden konnte, um Ionenkan{\"a}le zu analysieren. Nach entsprechender Forschung k{\"o}nnte die etablierte Methode in Zukunft auch auf andere Membranproteine ausgeweitet werden. Dies umfasst die Untersuchung anderer zell-frei exprimierte GPCRs oder anderer Ionenkan{\"a}le wie Kalium-, Natrium- und Chlorid-Ionenkan{\"a}le.}, language = {de} } @phdthesis{Malchow2023, author = {Malchow, Anne-Kathleen}, title = {Developing an integrated platform for predicting niche and range dynamics}, doi = {10.25932/publishup-60273}, url = {http://nbn-resolving.de/urn:nbn:de:kobv:517-opus4-602737}, school = {Universit{\"a}t Potsdam}, pages = {xiv, 169}, year = {2023}, abstract = {Species are adapted to the environment they live in. Today, most environments are subjected to rapid global changes induced by human activity, most prominently land cover and climate changes. Such transformations can cause adjustments or disruptions in various eco-evolutionary processes. The repercussions of this can appear at the population level as shifted ranges and altered abundance patterns. This is where global change effects on species are usually detected first. To understand how eco-evolutionary processes act and interact to generate patterns of range and abundance and how these processes themselves are influenced by environmental conditions, spatially-explicit models provide effective tools. They estimate a species' niche as the set of environmental conditions in which it can persist. However, the currently most commonly used models rely on static correlative associations that are established between a set of spatial predictors and observed species distributions. For this, they assume stationary conditions and are therefore unsuitable in contexts of global change. Better equipped are process-based models that explicitly implement algorithmic representations of eco-evolutionary mechanisms and evaluate their joint dynamics. These models have long been regarded as difficult to parameterise, but an increased data availability and improved methods for data integration lessen this challenge. Hence, the goal of this thesis is to further develop process-based models, integrate them into a complete modelling workflow, and provide the tools and guidance for their successful application. With my thesis, I presented an integrated platform for spatially-explicit eco-evolutionary modelling and provided a workflow for their inverse calibration to observational data. In the first chapter, I introduced RangeShiftR, a software tool that implements an individual-based modelling platform for the statistical programming language R. Its open-source licensing, extensive help pages and available tutorials make it accessible to a wide audience. In the second chapter, I demonstrated a comprehensive workflow for the specification, calibration and validation of RangeShiftR by the example of the red kite in Switzerland. The integration of heterogeneous data sources, such as literature and monitoring data, allowed to successfully calibrate the model. It was then used to make validated, spatio-temporal predictions of future red kite abundance. The presented workflow can be adopted to any study species if data is available. In the third chapter, I extended RangeShiftR to directly link demographic processes to climatic predictors. This allowed me to explore the climate-change responses of eight Swiss breeding birds in more detail. Specifically, the model could identify the most influential climatic predictors, delineate areas of projected demographic suitability, and attribute current population trends to contemporary climate change. My work shows that the application of complex, process-based models in conservation-relevant contexts is feasible, utilising available tools and data. Such models can be successfully calibrated and outperform other currently used modelling approaches in terms of predictive accuracy. Their projections can be used to predict future abundances or to assess alternative conservation scenarios. They further improve our mechanistic understanding of niche and range dynamics under climate change. However, only fully mechanistic models, that include all relevant processes, allow to precisely disentangle the effects of single processes on observed abundances. In this respect, the RangeShiftR model still has potential for further extensions that implement missing influential processes, such as species interactions. Dynamic, process-based models are needed to adequately model a dynamic reality. My work contributes towards the advancement, integration and dissemination of such models. This will facilitate numeric, model-based approaches for species assessments, generate ecological insights and strengthen the reliability of predictions on large spatial scales under changing conditions.}, language = {en} } @phdthesis{Kulshreshtha2023, author = {Kulshreshtha, Ritika}, title = {Dissecting the functional of role of microtubule and cellulose microfibril patterning during flower development in Arabidopsis}, school = {Universit{\"a}t Potsdam}, pages = {215}, year = {2023}, language = {en} } @article{Pandey2023, author = {Pandey, Yogesh}, title = {Enriched cell-free and cell-based native membrane derived vesicles (nMV) enabling rapid in-vitro electrophysiological analysis of the voltage-gated sodium channel 1.5.}, series = {Biochimica et Biophysica Acta (BBA) - Biomembranes}, volume = {1865}, journal = {Biochimica et Biophysica Acta (BBA) - Biomembranes}, number = {5}, publisher = {Elsevier}, address = {Amsterdam}, issn = {1879-2642}, doi = {10.1016/j.bbamem.2023.184144}, year = {2023}, abstract = {Here, we demonstrate the utility of native membrane derived vesicles (nMVs) as tools for expeditious electrophysiological analysis of membrane proteins. We used a cell-free (CF) and a cell-based (CB) approach for preparing protein-enriched nMVs. We utilized the Chinese Hamster Ovary (CHO) lysate-based cell-free protein synthesis (CFPS) system to enrich ER-derived microsomes in the lysate with the primary human cardiac voltage-gated sodium channel 1.5 (hNaV1.5; SCN5A) in 3 h. Subsequently, CB-nMVs were isolated from fractions of nitrogen-cavitated CHO cells overexpressing the hNaV1.5. In an integrative approach, nMVs were micro-transplanted into Xenopus laevis oocytes. CB-nMVs expressed native lidocaine-sensitive hNaV1.5 currents within 24 h; CF-nMVs did not elicit any response. Both the CB- and CF-nMV preparations evoked single-channel activity on the planar lipid bilayer while retaining sensitivity to lidocaine application. Our findings suggest a high usability of the quick-synthesis CF-nMVs and maintenance-free CB-nMVs as ready-to-use tools for in-vitro analysis of electrogenic membrane proteins and large, voltage-gated ion channels.}, language = {en} }