Refine
Year of publication
- 2023 (65) (remove)
Document Type
- Doctoral Thesis (51)
- Article (11)
- Postprint (3)
Language
- English (65) (remove)
Is part of the Bibliography
- yes (65)
Keywords
- 5-methoxycarbonylmethyl-2-thiouridine (3)
- Arabidopsis thaliana (3)
- H2S biosynthesis (3)
- Klimawandel (3)
- Moco biosynthesis (3)
- cellular bioenergetics (3)
- climate change (3)
- cytosolic tRNA thiolation (3)
- photosynthesis (3)
- sulfite oxidase (3)
- Ausbreitung (2)
- Evolutionsbiologie (2)
- Immunoassay (2)
- Photosynthese (2)
- Pipistrellus nathusii (2)
- Solanum tuberosum (2)
- Stärke (2)
- Zooplankton (2)
- acoustic communication (2)
- adaptation (2)
- animal migration (2)
- bats (2)
- dispersal (2)
- eavesdropping (2)
- echolocation (2)
- ecology (2)
- evolutionary biology (2)
- fluctuating light (2)
- genomics (2)
- immunoassay (2)
- metabolomics (2)
- phonotaxis (2)
- playback (2)
- potato (2)
- starch (2)
- (Xeno)Hormone (1)
- (xeno)hormones (1)
- 10-Formyltetrahydrofolat (1)
- 10-Formyltetrahydrofolate (1)
- 26S-Proteasom-System-Abbau (1)
- 3-Phosphoglycerinsäure (1)
- 5,10-Methenyltetrahydrofolat (1)
- 5,10-Methenyltetrahydrofolate (1)
- 5,10-Methylenetetrahydrofolate (1)
- 5-Methoxycarbonylmethyl-2-Thiouridin (1)
- 5-Methylaminomethyl-2-Thiouridin (1)
- 5-Methyltetrahydrofolat (1)
- 5-Methyltetrahydrofolate (1)
- 5-methylaminomethyl-2-thiouridine (1)
- 60S maturation (1)
- 60S-Reifung (1)
- AC Elektrokinetik (1)
- AC Elektroosmosis (1)
- AC electrokinetics (1)
- AC electroosmosis (1)
- Adaptation (1)
- African weakly electric fish (1)
- Amperometrie (1)
- Anpassung (1)
- Antarctica (1)
- Antibiotikaresistenz (1)
- Antibody (1)
- Antikörper (1)
- Arealverschiebungen (1)
- Artverbreitungsmodelle (1)
- Assemblierungsfaktor (1)
- Auxin (1)
- B. calyciflorus species complex (1)
- BROAD LEAF1 (1)
- Bakterien (1)
- Bakteriophagen (1)
- Barley (1)
- Bayes'sche Inferenz (1)
- Bayesian inference (1)
- Beschleunigungsmessungen (1)
- Bewegungsökologie (1)
- Biodiversität (1)
- Biofilm (1)
- Biogenese (1)
- Biomolekülinteraktionen (1)
- Biosensoren (1)
- Blattbreite (1)
- Brassinosteriods (1)
- CED (1)
- CHO-THF, CH-THF, CH2-THF und CH3-THF (1)
- CHO-THF, CH-THF, CH2-THF, and CH3-THF (1)
- Carlini Station (1)
- Cell-free protein synthesis (1)
- Central America (1)
- Chelonia mydas (1)
- Chytridiomycota (1)
- Codierungssequenz (1)
- Cold acclimation (1)
- Cytosolische Translation in Pflanzen (1)
- DNA (1)
- DNA Methylation (1)
- DNA metabarcoding (1)
- DNA-Aptamer (1)
- Darmkrebs (1)
- Dermochelys coriacea (1)
- Dielektrophorese (1)
- Dissertation (1)
- E. coli (1)
- Ein Kohlenstoff (1)
- Einzelzell-Analyse (1)
- Einzelzell-Sequenzierung (1)
- Electrophysiology (1)
- Energiebudget (1)
- Enzym (1)
- Epigenetics (1)
- European hare (1)
- Evolutionsrunde (1)
- FLC (1)
- FLOWERING LOCUS C (1)
- Feldhase (1)
- Filamente (1)
- Fis (1)
- Fluoreszenzfluktuationsspektroskopie (1)
- Fluoreszenzkorrelationspektroskopie (1)
- Fluoreszenzmikroskopie (1)
- Fortbewegung (1)
- FtsZ (1)
- FtsZ ring assemby (1)
- FtsZ-Ringbildung (1)
- Futtersuchverhalten (1)
- G protein-coupled estrogen receptor (1)
- G protein-gekoppelter Östrogen Rezeptor (1)
- GPS (1)
- Genomik (1)
- Gerste (1)
- Glycin-Decarboxylase-Komplex (=GCV) (1)
- Glycin-Spaltsystem (1)
- Glycin-Synthase-Komplex (Umkehrung von GCV) (1)
- Grünland (1)
- H2S-Biosynthese (1)
- H3K27me3 Methylation (1)
- Hantaviren (1)
- Hantavirus (1)
- Heat stress memory, Heat shock factors, Mediator subunits, MED23, MED32, Arabidopsis thaliana (1)
- Histone Modification (1)
- Holozän (1)
- Hordeum vulgare (1)
- Hybridisierung (1)
- IBD (1)
- INDETERMINATE DOMAIN protein (1)
- INDETERMINATE DOMAIN-Protein (1)
- Illumina amplicon sequencing (1)
- Influenza (1)
- Influenza A Virus (1)
- Interaktion (1)
- Interaktions Netzwerk (1)
- JUMONJI (1)
- Jaguar (1)
- Kartoffel (1)
- Kaskadeneffekte (1)
- Koexistenz (1)
- Kompromiss (1)
- Konfokale Mikroskopie (1)
- Konsequenzen von Fang und Besenderung (1)
- Krebs (1)
- Krebsbiomarker (1)
- Krebserkennung (1)
- Krebstherapie (1)
- Kälteakklimatisierung (1)
- LOC (1)
- Landnutzung (1)
- Landschaft der Angst (1)
- Lebensmittelanalytik (1)
- Lebensraumnutzung (1)
- Lipopolysaccharid (1)
- Maltodextrin (1)
- Matrix (1)
- Membrane proteins (1)
- Membranfluidität (1)
- Metabolit (1)
- Metacommunity (1)
- Metagemeinschaft (1)
- Metallkation (1)
- Micro-translantation (1)
- Microscale Thermophoresis (MST) (1)
- Mikrofluidik (1)
- Mittelamerika (1)
- Moco-Biosynthese (1)
- Muskel-Skelett-System / Bewegungsapparat (1)
- Mykotoxine (1)
- Nanoelektroden (1)
- Neu-Delhi Metallo-Beta-Laktamase 1 (NDM-1) (1)
- New Delhi metallo-β-lactamase 1 (NDM-1) (1)
- Oberflächenplasmonenresonanzspektroskopie (SPR-Spektroskopie) (1)
- One-carbon (1)
- Open Access (1)
- Open Source (1)
- PGR5 (1)
- POC (1)
- PVA (population viability analysis) (1)
- Palmöl (1)
- Paläoökologie (1)
- Photosystem I (1)
- Pichia pastoris (1)
- Plant cytosolic translation (1)
- Pleistozän (1)
- Populationsdynamik (1)
- Populationsgefährdungsanalyse (1)
- Populationskonnektivität (1)
- Protein (1)
- Protein expression (1)
- Protein synthesis (1)
- Protein-Aptamer Interaktion (1)
- Proteinmultimerisierung (1)
- Proteinrekonstitution (1)
- Proteinspiegel regulieren (1)
- Proteinsynthese (1)
- Python (1)
- QSP (1)
- RING/U-box E3 (1)
- Rahmenübereinkommen der Vereinten Nationen über Klimaänderungen (1)
- Reaktionsgeschwindigkeit (1)
- Repetition (1)
- Ribosomal protein heterogeneity (1)
- Ribosomal protein substoichiometry (1)
- Ribosomale Protein Substöchiometrie (1)
- Ribosomale Proteinheterogenität (1)
- Ribosome biogenesis (1)
- Ribosome specialization (1)
- Ribosomen-Biogenese (1)
- Ribosomen-Spezialisierung (1)
- Riesenvesikel (1)
- RpoS (1)
- SEPE Factors (1)
- SEPS factors (1)
- SVP (1)
- Saccharomyces cerevisiae (1)
- Samenausbreitung (1)
- Sandwich-Assay auf Basis von Aptameren (1)
- Schutz von Raubtieren (1)
- Seed Coat Development (1)
- Seed development (1)
- Sequenzierung der nächsten Generation (1)
- Serin-Biosensor (1)
- Serin-Hydroxymethyltransferase (1)
- Siberia (1)
- Sibirien (1)
- Simulationsframework (1)
- Skalierung (1)
- Source und Sink (1)
- St. Nicolas House Algorithm (1)
- St. Nicolas House Analysis (1)
- Stammzelldifferenzierung (1)
- Statistical Exercise (1)
- Stethophyma grossum (1)
- Stoffwechsel (1)
- Sulfit-Oxidase (1)
- Summer Schools (1)
- Sumpfschrecke (1)
- Surface Plasmon Resonance (SPR) (1)
- Systembiologie (1)
- Säugetiere (1)
- Thylakoidmembran (1)
- Tierortung (1)
- Tierpersönlichkeit (1)
- Tierökologie (1)
- Transkriptomik (1)
- Translational regulation (1)
- Translationseffizienz (1)
- Translationsregulation (1)
- Transponierbare Elemente (1)
- Treibhausgase (1)
- TusA (1)
- Ubiquitinierung (1)
- Umweltfilterung (1)
- Urokinase-Typ Plasminogen Aktivator (uPA) (1)
- Urokinase-type Plasminogen Activator (uPA) (1)
- Vesikel (1)
- Videoanalyse (1)
- Virionenbildung (1)
- Virus (1)
- Virus-Wirt-Interaktion (1)
- Viskoelastizität (1)
- Zeitpunkt von Störungen (1)
- Zellmembran (1)
- Zellproliferation (1)
- Zellteilung (1)
- Zellteilungsdefekt (1)
- Zentrosomen Amplifikation (1)
- accelerometry (1)
- adaptive Laborentwicklung (1)
- adaptive laboratory evolution (1)
- adaptive radiation (1)
- amperometry (1)
- animal personality (1)
- antibiotic resistance (1)
- antibody (1)
- aptamer-based sandwich assay (1)
- aquatic fungi (1)
- assembly factor (1)
- ausgewogener Komplex (1)
- autonom replizierende Sequenz (1)
- bacteria (1)
- bacteriophage (1)
- balanced complex (1)
- biodiversity (1)
- biofilm (1)
- biogenesis (1)
- biomolecule interactions (1)
- biosensors (1)
- body proportions (1)
- bootstrap (1)
- cancer (1)
- cancer biomarker (1)
- cancer detection (1)
- cancer therapy (1)
- cascading effects (1)
- catch-up-growth (1)
- cbFBA (1)
- cell division (1)
- cell membrane (1)
- cell proliferation (1)
- centrosome amplification (1)
- cetacean (1)
- changepoint analysis (1)
- changepoint detection (1)
- child growth (1)
- chromosomale Instabilität (1)
- coexistence (1)
- colon cancer (1)
- confocal microscopy (1)
- conservation (1)
- correlation (1)
- dielectrophoresis (1)
- disturbance timing (1)
- doctoral thesis (1)
- ecological modelling (1)
- ecological speciation (1)
- editing (1)
- education (1)
- endosymbiosis (1)
- energy budget (1)
- environment filtering (1)
- enzyme (1)
- evolution (1)
- felid conservation (1)
- filaments (1)
- fisheries management (1)
- flowering (1)
- fluktuierendes Licht (1)
- fluorescence correlation spectroscopy (1)
- fluorescence fluctuation spectroscopy (1)
- fluorescence microscopy (1)
- fluorescent proteins (1)
- fluoreszierende Proteine (1)
- food access (1)
- food analysis (1)
- foraging behaviour (1)
- functional traits (1)
- funktionale Merkmale (1)
- gene (1)
- genome (1)
- genome-wide association studies (GWAS) (1)
- genotype-by-Environmental interaction (GxE) (1)
- geometric morphometric (1)
- giant vesicles (1)
- giving-up density (1)
- glycine cleavage system (1)
- glycine decarboxylase complex (=GCV) (1)
- glycine synthase complex (reversal of GCV) (1)
- gram-negative (1)
- gramnegativ (1)
- grassland (1)
- green house gases (1)
- growth defect (1)
- habitat use (1)
- height in history (1)
- high resolution (1)
- hohe Auflösung (1)
- holocene (1)
- hybridization (1)
- individual-based modelling (1)
- individuen-basierte Modellierung (1)
- influenza (1)
- influenza A virus (1)
- interaction (1)
- interaction network (1)
- interactomics (1)
- jaguar (1)
- lab-on-chip (1)
- land use (1)
- landscape of fear (1)
- large marsh grasshopper (1)
- leaf width (1)
- lipopolysaccharide (1)
- low NPQ (1)
- malnutrition (1)
- maltodextrin (1)
- mammals (1)
- matrix (1)
- membrane fluidity (1)
- mesenchymal stromal cells (1)
- mesenchymale stromale Zellen (1)
- metabolic network (1)
- metabolisches Netzwerk (1)
- metabolism (1)
- metabolite (1)
- metal cation (1)
- microfluidics (1)
- migration (1)
- mini growth spurt (1)
- movement (1)
- movement ecology (1)
- musculoskeletal system (1)
- mycotoxins (1)
- nanoelectrodes (1)
- network reconstruction (1)
- next generation sequencing (1)
- nutrition (1)
- oil palm (1)
- organelles (1)
- pace of life (1)
- paleoecology (1)
- performance evaluation (1)
- phenomics (1)
- photosystem I (1)
- physical fitness (1)
- physical time (1)
- phytoplankton host (1)
- plant (1)
- plasticity (1)
- pleistocene (1)
- point-of-care (1)
- population connectivity (1)
- population dynamics (1)
- proteasomal degradation (1)
- protein (1)
- protein multimerization (1)
- protein reconstitution (1)
- protein-aptamer interaction (1)
- protein-level regulation (1)
- proteomics (1)
- pubertal timing (1)
- public health (1)
- range shifts (1)
- reaction rate (1)
- reductive acetyl-CoA pathway (1)
- reductive glycine pathway (1)
- reduktiver Acetyl-CoA-Weg (1)
- reduktiver Glycinweg (1)
- repair (1)
- räumlich explizites Modell (1)
- saccharomyces cerevisiae (1)
- salinity gradient (1)
- scaling (1)
- secular changes (1)
- sedaDNA (1)
- seed dispersal (1)
- serine biosensor (1)
- serine hydroxymethyltransferase (1)
- short vegetative phase (1)
- short-term growth (1)
- simulation framework (1)
- single cell imaging (1)
- single-cell RNA-sequencing (1)
- single-cell analysis (1)
- social network (1)
- socioeconomy (1)
- source and sink (1)
- spatially explicit model (1)
- species distribution modelling (1)
- stem cell differentiation (1)
- stock assessment (1)
- stock structure (1)
- stunting (1)
- suppressor mutant screen (1)
- synthetic biology (1)
- synthetic formatotrphy (1)
- synthetische Biologie (1)
- systems biology (1)
- tRNA Thiomodifikation (1)
- tRNA thiomodifications (1)
- thylakoid membranes (1)
- tracking (1)
- tracking impacts (1)
- trade-off (1)
- transcriptomics (1)
- transfer (1)
- translation efficiency (1)
- transposable elements (1)
- trophic apparatus (1)
- tuber second growth (1)
- tuberization (1)
- ubiquitination (1)
- vesicle (1)
- video analysis (1)
- virus (1)
- virus assembly (1)
- virus-host interaction (1)
- viscoelasticity (1)
- whole chromosomal instability (1)
- zelluläre Bioenergetik (1)
- zooplankton (1)
- zytosolische tRNA-Thiolierung (1)
- Ökologie (1)
- ökologische Modellierung (1)
Institute
- Institut für Biochemie und Biologie (65) (remove)
Light is the essential energy source for plants to drive photosynthesis. In nature, light availability is highly variable and often fluctuates on very short time scales. As a result, plants developed mechanisms to cope with these fluctuations. Understanding how to improve light use efficiency in natural fluctuating light (FL) conditions is a major target for agronomy.
In the first project, we identified an Arabidopsis thaliana plant that showed reduced levels of rapidly inducible non-photochemical quenching (NPQ). This plant was devoid of any T-DNA insertion. Using a mapping-by-sequencing approach, we successfully located the causal genomic region near the end of chromosome 4. Through variant investigations in that region, we identified a deletion of about 20 kb encompassing 9 genes. By complementation analysis, we confirmed that one of the deleted genes, VTC2, is the causal gene responsible for the low NPQ. Loss of VTC2 decreased NPQ particularly in old leaves, with young leaves being only slightly affected. Additionally, ascorbate levels were almost abolished in old leaves, likely causing the NPQ decrease by reducing the activity of the xanthophyll cycle. Although ascorbate levels in younger leaves were reduced compared to wild-type plants, they remained at a comparably higher level. This difference may be due to the VTC2 paralog VTC5, which is expressed at a higher level in young leaves than in old ones.
Plants require the PROTON GRADIENT REGULATION 5 (PGR5) protein for survival in FL. pgr5 mutants die because they fail to increase the luminal proton concentration in response to high light (HL) phases. A rapid elevation in ∆pH is needed to slow down electron transport through the Cytochrome b6 f complex (photosynthetic control). In FL, such lack of control in the pgr5 mutants results in photosystem I (PSI) overreduction, reactive oxygen species (ROS) production, and cell death. Decreases in photosystem II (PSII) activity introduced by crossing pgr5 with PSII deficient mutants
rescued the lethality of pgr5 in FL. PGR5 was suggested to act as part of the ferredoxin-plastoquinone reductase (FQR), involved in cyclic electron transfer around PSI. However, the proposed molecular role of PGR5 remains highly debated. To learn more about PGR5 function, we performed a forward genetic screen in Arabidopsis thaliana to identify EMS-induced suppressor mutants surviving longer when grown in FL compared to pgr5 mutants (referred to as ”suppressor of pgr5 lethality in fluctuating light”, splf ). 11 different candidate genes were identified in a total of 22 splf plants.
Mutants of seven of these genes in the pgr5 background showed low Fv/Fm values when grown in non-fluctuating low light (LL). Five of these 4genes were previously reported to have a role in PSII biogenesis or function. Two others, RPH1 and a DEAD/DEAH box helicase (AT3G02060), have not been linked to PSII function before. Three of splf candidate genes link to primary metabolism, fructose-2,6-bisphosphatase (F2KP ), udp-glucose pyrophosphorylase 1 (UGP1 ) and ferredoxin-dependent glutamate synthase (Fd-GOGAT ). They are characterized by the fact that they survive longer in FL than pgr5 mutants but do not procede beyond the early vegetative
phase and then die.
Plant metabolism serves as the primary mechanism for converting assimilated carbon into essential compounds crucial for plant growth and ultimately, crop yield. This renders it a focal point of research with significant implications. Despite notable strides in comprehending the genetic principles underpinning metabolism and yield, there remains a dearth of knowledge regarding the genetic factors responsible for trait variation under varying environmental conditions. Given the burgeoning global population and the advancing challenges posed by climate change, unraveling the intricacies of metabolic and yield responses to water scarcity became increasingly important in safeguarding food security.
Our research group has recently started to work on the genetic resources of legume species. To this end, the study presented here investigates the metabolic diversity across five different legume species at a tissue level, identifying species-specific biosynthesis of alkaloids as well as iso-/flavonoids with diverse functional groups, namely prenylation, phenylacylation as well as methoxylation, to create a resource for follow up studies investigation the metabolic diversity in natural diverse populations of legume species.
Following this, the second study investigates the genetic architecture of drought-induced changes in a global common bean population. Here, a plethora of quantitative trait loci (QTL) associated with various traits are identified by performing genome-wide association studies (GWAS), including for lipid signaling. On this site, overexpression of candidates highlighted the induction of several oxylipins reported to be pivotal in coping with harsh environmental conditions such as water scarcity.
Diverging from the common bean and GWAS, the following study focuses on identifying drought-related QTL in tomato using a bi-parental breeding population. This descriptive study highlights novel multi-omic QTL, including metabolism, photosynthesis as well as fruit setting, some of which are uniquely assigned under drought. Compared to conventional approaches using the bi-parental IL population, the study presented improves the resolution by assessing further backcrossed ILs, named sub-ILs.
In the final study, a photosynthetic gene, namely a PetM subunit of the cytochrome b6f complex encoding gene, involved in electron flow is characterized in an horticultural important crop. While several advances have been made in model organisms, this study highlights the transition of this fundamental knowledge to horticultural important crops, such as tomato, and investigates its function under differing light conditions. Overall, the presented thesis combines different strategies in unveiling the genetic components in multi-omic traits under drought using conventional breeding populations as well as a diverse global population. To this end, it allows a comparison of either approach and highlights their strengths and weaknesses.
Animal movement is a crucial aspect of life, influencing ecological and evolutionary processes. It plays an important role in shaping biodiversity patterns, connecting habitats and ecosystems. Anthropogenic landscape changes, such as in agricultural environments, can impede the movement of animals by affecting their ability to locate resources during recurring movements within home ranges and, on a larger scale, disrupt migration or dispersal. Inevitably, these changes in movement behavior have far-reaching consequences on the mobile link functions provided by species inhabiting such extensively altered matrix areas. In this thesis, I investigate the movement characteristics and activity patterns of the European hare (Lepus europaeus), aiming to understand their significance as a pivotal species in fragmented agricultural landscapes. I reveal intriguing results that shed light on the importance of hares for seed dispersal, the influence of personality traits on behavior and space use, the sensitivity of hares to extreme weather conditions, and the impacts of GPS collaring on mammals' activity patterns and movement behavior.
In Chapter I, I conducted a controlled feeding experiment to investigate the potential impact of hares on seed dispersal. By additionally utilizing GPS data of hares in two contrasting landscapes, I demonstrated that hares play a vital role, acting as effective mobile linkers for many plant species in small and isolated habitat patches. The analysis of seed intake and germination success revealed that distinct seed traits, such as density, surface area, and shape, profoundly affect hares' ability to disperse seeds through endozoochory. These findings highlight the interplay between hares and plant communities and thus provide valuable insights into seed dispersal mechanisms in fragmented landscapes.
By employing standardized behavioral tests in Chapter II, I revealed consistent behavioral responses among captive hares while simultaneously examining the intricate connection between personality traits and spatial patterns within wild hare populations. This analysis provides insights into the ecological interactions and dynamics within hare populations in agricultural habitats. Examining the concept of animal personality, I established a link between personality traits and hare behavior. I showed that boldness, measured through standardized tests, influences individual exploration styles, with shy and bold hares exhibiting distinct space use patterns. In addition to providing valuable insights into the role of animal personality in heterogeneous environments, my research introduced a novel approach demonstrating the feasibility of remotely assessing personality types using animal-borne sensors without additional disturbance of the focal individual.
While climate conditions severely impact the activity and, consequently, the fitness of wildlife species across the globe, in Chapter III, I uncovered the sensitivity of hares to temperature, humidity, and wind speed during their peak reproduction period. I found a strong response in activity to high temperatures above 25°C, with a particularly pronounced effect during temperature extremes of over 35°C. The non-linear relationship between temperature and activity was characterized by contrasting responses observed for day and night. These findings emphasize the vulnerability of hares to climate change and the potential consequences for their fitness and population dynamics with the ongoing rise of temperature.
Since such insights can only be obtained through capturing and tagging free-ranging animals, I assessed potential impacts and the recovery process post-collar attachment in Chapter IV. For this purpose, I examined the daily distances moved and the temporal-associated activity of 1451 terrestrial mammals out of 42 species during their initial tracking period. The disturbance intensity and the speed of recovery varied across species, with herbivores, females, and individuals captured and collared in relatively secluded study areas experiencing more pronounced disturbances due to limited anthropogenic influences.
Mobile linkers are essential for maintaining biodiversity as they influence the dynamics and resilience of ecosystems. Furthermore, their ability to move through fragmented landscapes makes them a key component for restoring disturbed sites. Individual movement decisions determine the scale of mobile links, and understanding variations in space use among individuals is crucial for interpreting their functions. Climate change poses further challenges, with wildlife species expected to adjust their behavior, especially in response to high-temperature extremes, and comprehending the anthropogenic influence on animal movements will remain paramount to effective land use planning and the development of successful conservation strategies.
This thesis provides a comprehensive ecological understanding of hares in agricultural landscapes. My research findings underscore the importance of hares as mobile linkers, the influence of personality traits on behavior and spatial patterns, the vulnerability of hares to extreme weather conditions, and the immediate consequences of collar attachment on mammalian movements. Thus, I contribute valuable insights to wildlife conservation and management efforts, aiding in developing strategies to mitigate the impact of environmental changes on hare populations. Moreover, these findings enable the development of methodologies aimed at minimizing the impacts of collaring while also identifying potential biases in the data, thereby benefiting both animal welfare and the scientific integrity of localization studies.
In this work, the role of the TusA protein was investigated for the cell functionality and FtsZ ring assembly in Escherichia coli. TusA is the tRNA-2-thiouridine synthase that acts as a sulfur transferase in tRNA thiolation for the formation of 2-thiouridine at the position 34 (wobble base) of tRNALys, tRNAGlu and tRNAGln. It binds the persulfide form of sulfur and transfers it to further proteins during mnm5s2U tRNA modification at wobble position and for Moco biosynthesis. With this thiomodification of tRNA, the ribosome binding is more efficient and frameshifting is averted during the protein translation. Previous studies have revealed an essential role of TusA in bacterial cell physiology since deletion of the tusA gene resulted in retarded growth and filamentous cells during the exponential growth phase in a rich medium which suddenly disappeared during the stationary phase. This indicates a problem in the cell division process. Therefore the focus of this work was to investigate the role of TusA for cell functionality and FtsZ ring formation and thus the cell separation.
The reason behind the filamentous growth of the tusA mutant strain was investigated by growth and morphological analyses. ΔtusA cells showed a retarded growth during the exponential phase compared to the WT strain. Also, morphological analysis of ΔtusA cells confirmed the filamentous cell shape. The growth and cell division defects in ΔtusA indicated a defect in FtsZ protein as a key player of cell division. The microscopic investigation revealed that filamentous ΔtusA cells possessed multiple DNA parts arranged next to each other. This suggested that although the DNA replication occurred correctly, there was a defect in the step where FtsZ should act; probably FtsZ is unable to assemble to the ring structure or the assembled ring is not able to constrict. All tested mutant strains (ΔtusD, ΔtusE and ΔmnmA) involved in the mnm5s2U34 tRNA modification pathway shared the similar retarded growth and filamentous cell shape like ΔtusA strain. Thus, the cell division defect arises from a defect in mnm5s2U34 tRNA thiolation.
Since the FtsZ ring formation was supposed to be defective in filaments, a possible intracellular interaction of TusA and FtsZ was examined by fluorescent (EGFP and mCherry) fusion proteins expression and FRET. FtsZ expressing tusA mutant (DE3) cells showed a red mCherry signal at the cell poles, indicating that FtsZ is still in the assembling phase. Interestingly, the cellular region of EGFP-TusA fusion protein expressed in ΔtusA (DE3) was conspicuous; the EGFP signal was spread throughout the whole cell and, in addition, a slight accumulation of the EGFP-TusA fluorescence was detectable at the cell poles, the same part of the cell as for mCherry-FtsZ. Thus, this strongly suggested an interaction of TusA and FtsZ.
Furthermore, the cellular FtsZ and Fis concentrations, and their change during different growth phases were determined via immunoblotting. All tested deletion strains of mnm5s2U34 tRNA modification show high cellular FtsZ and Fis levels in the exponential phase, shifting to the later growth phases. This shift reflects the retarded growth, whereby the deletion strains reach later the exponential phase. Conclusively, the growth and cell division defect, and thus the formation of filaments, is most likely caused by changes in the cellular FtsZ and Fis concentrations.
Finally, the translation efficiencies of certain proteins (RpoS, Fur, Fis and mFis) in tusA mutant and in additional gene deletion strains were studied whether they were affected by using unmodified U34 tRNAs of Lys, Glu and Gln. The translation efficiency is decreased in mnm5s2U34 tRNA modification-impaired strains in addition to their existing growth and cell division defect due to the elimination of these three amino acids. Finally, these results confirm and reinforce the importance of Lys, Glu and Gln and the mnm5s2U34 tRNA thiolation for efficient protein translation. Thus, these findings verify that the translation of fur, fis and rpoS is regulated by mnm5s2U34 tRNA modifications, which is growth phase-dependent.
In total, this work showed the importance of the role of TusA for bacterial cell functionality and physiology. The deletion of the tusA gene disrupted a complex regulatory network within the cell, that most influenced by the decreased translation of Fis and RpoS, caused by the absence of mnm5s2U34 tRNA modifications. The disruption of RpoS and Fis cellular network influences in turn the cellular FtsZ level in the early exponential phase. Finally, the reduced FtsZ concentration leads to elongated, filamentous E. coli cells, which are unable to divide.
The development of seeds in angiosperms starts with a complex process of double fertilization, involving the fusion of the maternal egg cell and central cell with two paternal sperm cells. This gives rise to the embryo and the nourishing endosperm, which are then enclosed by the seed coat, derived from the maternal integuments. The growth of the seed coat in Arabidopsis thaliana (Arabidopsis) is actively inhibited before fertilization by epigenetic regulators known as Polycomb Group (PcG) proteins. These proteins deposit a repressive histone mark called H3K27me3, which must be removed to enable seed coat formation. In this thesis, I explored the mechanism of removal of H3K27me3 marks from the integument cells following fertilization, which allows for seed coat formation. We hypothesized that this removal should be primarily facilitated by histone demethylases from the JMJ family and potentially influenced by the plant hormones Brassinosteroids (BRs). This hypothesis was supported by the expression patterns of the JMJ protein REF6 and of BR related genes, which are specifically expressed in the integuments and in the seed coat. Moreover, mutations in both these pathways lead to developmental defects, such as reduced ovule viability and delayed seed coat growth. Our research provides evidence suggesting that BR signalling is likely involved in recruiting JMJ-type histone demethylases to target loci responsible for seed coat growth. Moreover, we have discovered an additional pathway through which BRs regulate seed coat development, independent of their influence on H3K27me3 marks. This finding emphasizes the diverse roles of BRs in coordinating seed development, extending beyond their well-known involvement in plant growth and development. Furthermore, I explored the role of another epigenetic mark, DNA methylation, in fertilization-independent (or autonomous) seed formation in Arabidopsis. For this, we utilized epigenetic Recombinant Inbred Lines (epiRILs) and thus identified an epigenetic Quantitative Trait Locus (epiQTL) on chromosome II, potentially responsible for the larger autonomous seed size observed in DNA methylation mutants. Overall, this thesis significantly enhances our comprehension of the intricate relationship between epigenetic modifications, hormonal signaling, and plant reproductive processes. It offers valuable insights into the genetic mechanisms governing both sexual and asexual seed formation, while also presenting potential avenues for the engineer of advantageous traits in agricultural crops.
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.
Starch is a biopolymer for which, despite its simple composition, understanding the precise mechanism behind its formation and regulation has been challenging. Several approaches and bioanalytical tools can be used to expand the knowledge on the different parts involved in the starch metabolism. In this sense, a comprehensive analysis targeting two of the main groups of molecules involved in this process: proteins, as effectors/regulators of the starch metabolism, and maltodextrins as starch components and degradation products, was conducted in this research work using potato plants (Solanum tuberosum L. cv. Desiree) as model of study. On one side, proteins physically interacting to potato starch were isolated and analyzed through mass spectrometry and western blot for their identification. Alternatively, starch interacting proteins were explored in potato tubers from transgenic plants having antisense inhibition of starch-related enzymes and on tubers stored under variable environmental conditions. Most of the proteins recovered from the starch granules corresponded to previously described proteins having a specific role in the starch metabolic pathway. Another set of proteins could be grouped as protease inhibitors, which were found weakly interacting to starch. Variations in the protein profile obtained after electrophoresis separation became clear when tubers were stored under different temperatures, indicating a differential expression of proteins in response to changing environmental conditions.
On the other side, since maltodextrin metabolism is thought to be involved in both starch initiation and degradation, soluble maltooligosaccharide content in potato tubers was analyzed in this work under diverse experimental variables. For this, tuber disc samples from wild type and transgenic lines strongly repressing either the plastidial or cytosolic form of the -glucan phosphorylase and phosphoglucomutase were incubated with glucose, glucose-6-phosphate, and glucose-1-phosphate solutions to evaluate the influence of such enzymes on the conversion of the carbon sources into soluble maltodextrins, in comparison to wild-type samples. Relative maltodextrin amounts analyzed through capillary electrophoresis equipped with laser-induced fluorescence (CE-LIF) revealed that tuber discs could immediately uptake glucose-1-phosphate and use it to produce maltooligosaccharides with a degree of polymerization of up to 30 (DP30), in contrast to transgenic tubers with strong repression of the plastidial glucan phosphorylase. The results obtained from the maltodextrin analysis support previous indications that a specific transporter for glucose-1-phosphate may exist in both the plant cells and the plastidial membranes, thereby allowing a glucose-6-phosphate independent transport. Furthermore, it confirms that the plastidial glucan phosphorylase is responsible for producing longer maltooligosaccharides in the plastids by catalyzing a glucan polymerization reaction when glucose-1-phosphate is available. All these findings contribute to a better understanding of the role of the plastidial glucan phosphorylase as a key enzyme directly involved in the synthesis and degradation of glucans and their implication on starch metabolism.