@article{RuzanskiSmirnovaRejzeketal.2013, author = {Ruzanski, Christian and Smirnova, Julia and Rejzek, Martin and Cockburn, Darrell and Pedersen, Henriette L. and Pike, Marilyn and Willats, William G. T. and Svensson, Birte and Steup, Martin and Ebenh{\"o}h, Oliver and Smith, Alison M. and Field, Robert A.}, title = {A bacterial glucanotransferase can replace the complex maltose metabolism required for starch to sucrose conversion in leaves at night}, series = {The journal of biological chemistry}, volume = {288}, journal = {The journal of biological chemistry}, number = {40}, publisher = {American Society for Biochemistry and Molecular Biology}, address = {Bethesda}, issn = {0021-9258}, doi = {10.1074/jbc.M113.497867}, pages = {28581 -- 28598}, year = {2013}, abstract = {Controlled conversion of leaf starch to sucrose at night is essential for the normal growth of Arabidopsis. The conversion involves the cytosolic metabolism of maltose to hexose phosphates via an unusual, multidomain protein with 4-glucanotransferase activity, DPE2, believed to transfer glucosyl moieties to a complex heteroglycan prior to their conversion to hexose phosphate via a cytosolic phosphorylase. The significance of this complex pathway is unclear; conversion of maltose to hexose phosphate in bacteria proceeds via a more typical 4-glucanotransferase that does not require a heteroglycan acceptor. It has recently been suggested that DPE2 generates a heterogeneous series of terminal glucan chains on the heteroglycan that acts as a glucosyl buffer to ensure a constant rate of sucrose synthesis in the leaf at night. Alternatively, DPE2 and/or the heteroglycan may have specific properties important for their function in the plant. To distinguish between these ideas, we compared the properties of DPE2 with those of the Escherichia coli glucanotransferase MalQ. We found that MalQ cannot use the plant heteroglycan as an acceptor for glucosyl transfer. However, experimental and modeling approaches suggested that it can potentially generate a glucosyl buffer between maltose and hexose phosphate because, unlike DPE2, it can generate polydisperse malto-oligosaccharides from maltose. Consistent with this suggestion, MalQ is capable of restoring an essentially wild-type phenotype when expressed in mutant Arabidopsis plants lacking DPE2. In light of these findings, we discuss the possible evolutionary origins of the complex DPE2-heteroglycan pathway.}, language = {en} } @article{BadalyanNeumannSchaalLeimkuehleretal.2013, author = {Badalyan, Artavazd and Neumann-Schaal, Meina and Leimk{\"u}hler, Silke and Wollenberger, Ursula}, title = {A Biosensor for aromatic aldehydes comprising the mediator dependent PaoABC-Aldehyde oxidoreductase}, series = {Electroanalysis : an international journal devoted to fundamental and practical aspects of electroanalysis}, volume = {25}, journal = {Electroanalysis : an international journal devoted to fundamental and practical aspects of electroanalysis}, number = {1}, publisher = {Wiley-VCH}, address = {Weinheim}, issn = {1040-0397}, doi = {10.1002/elan.201200362}, pages = {101 -- 108}, year = {2013}, abstract = {A novel aldehyde oxidoreductase (PaoABC) from Escherichia coli was utilized for the development of an oxygen insensitive biosensor for benzaldehyde. The enzyme was immobilized in polyvinyl alcohol and currents were measured for aldehyde oxidation with different one and two electron mediators with the highest sensitivity for benzaldehyde in the presence of hexacyanoferrate(III). The benzaldehyde biosensor was optimized with respect to mediator concentration, enzyme loading and pH using potassium hexacyanoferrate(III). The linear measuring range is between 0.5200 mu M benzaldehyde. In correspondence with the substrate selectivity of the enzyme in solution the biosensor revealed a preference for aromatic aldehydes and less effective conversion of aliphatic aldehydes. The biosensor is oxygen independent, which is a particularly attractive feature for application. The biosensor can be applied to detect contaminations with benzaldehyde in solvents such as benzyl alcohol, where traces of benzaldehyde in benzyl alcohol down to 0.0042?\% can be detected.}, language = {en} } @article{AllanWeisserFischeretal.2013, author = {Allan, Eric and Weisser, Wolfgang W. and Fischer, Markus and Schulze, Ernst-Detlef and Weigelt, Alexandra and Roscher, Christiane and Baade, Jussi and Barnard, Romain L. and Bessler, Holger and Buchmann, Nina and Ebeling, Anne and Eisenhauer, Nico and Engels, Christof and Fergus, Alexander J. F. and Gleixner, Gerd and Gubsch, Marlen and Halle, Stefan and Klein, Alexandra-Maria and Kertscher, Ilona and Kuu, Annely and Lange, Markus and Le Roux, Xavier and Meyer, Sebastian T. and Migunova, Varvara D. and Milcu, Alexandru and Niklaus, Pascal A. and Oelmann, Yvonne and Pasalic, Esther and Petermann, Jana S. and Poly, Franck and Rottstock, Tanja and Sabais, Alexander C. W. and Scherber, Christoph and Scherer-Lorenzen, Michael and Scheu, Stefan and Steinbeiss, Sibylle and Schwichtenberg, Guido and Temperton, Vicky and Tscharntke, Teja and Voigt, Winfried and Wilcke, Wolfgang and Wirth, Christian and Schmid, Bernhard}, title = {A comparison of the strength of biodiversity effects across multiple functions}, series = {Oecologia}, volume = {173}, journal = {Oecologia}, number = {1}, publisher = {Springer}, address = {New York}, issn = {0029-8549}, doi = {10.1007/s00442-012-2589-0}, pages = {223 -- 237}, year = {2013}, abstract = {In order to predict which ecosystem functions are most at risk from biodiversity loss, meta-analyses have generalised results from biodiversity experiments over different sites and ecosystem types. In contrast, comparing the strength of biodiversity effects across a large number of ecosystem processes measured in a single experiment permits more direct comparisons. Here, we present an analysis of 418 separate measures of 38 ecosystem processes. Overall, 45 \% of processes were significantly affected by plant species richness, suggesting that, while diversity affects a large number of processes not all respond to biodiversity. We therefore compared the strength of plant diversity effects between different categories of ecosystem processes, grouping processes according to the year of measurement, their biogeochemical cycle, trophic level and compartment (above- or belowground) and according to whether they were measures of biodiversity or other ecosystem processes, biotic or abiotic and static or dynamic. Overall, and for several individual processes, we found that biodiversity effects became stronger over time. Measures of the carbon cycle were also affected more strongly by plant species richness than were the measures associated with the nitrogen cycle. Further, we found greater plant species richness effects on measures of biodiversity than on other processes. The differential effects of plant diversity on the various types of ecosystem processes indicate that future research and political effort should shift from a general debate about whether biodiversity loss impairs ecosystem functions to focussing on the specific functions of interest and ways to preserve them individually or in combination.}, language = {en} } @article{BukovinszkyHelmsingGrauetal.2013, author = {Bukovinszky, Tibor and Helmsing, Nico R. and Grau, R. A. and Bakker, Elisabeth S. and Bezemer, T. Martijn and Vos, Matthijs and Uittenhout, H. and Verschoor, A. M.}, title = {A device to study the behavioral responses of zooplankton to food quality and quantity}, series = {Journal of insect behavior}, volume = {26}, journal = {Journal of insect behavior}, number = {4}, publisher = {Springer}, address = {New York}, issn = {0892-7553}, doi = {10.1007/s10905-012-9366-0}, pages = {453 -- 465}, year = {2013}, abstract = {In order to explore the behavioral mechanisms underlying aggregation of foragers on local resource patches, it is necessary to manipulate the location, quality and quantity of food patches. This requires careful control over the conditions in the foraging arena, which may be a challenging task in the case of aquatic resource-consumer systems, like that of freshwater zooplankton feeding on suspended algal cells. We present an experimental tool designed to aid behavioral ecologists in exploring the consequences of resource characteristics for zooplankton aggregation behavior and movement decisions under conditions where the boundaries and characteristics (quantity and quality) of food patches can be standardized. The aggregation behavior of Daphnia magna and D. galeata x hyalina was tested in relation to i) the presence or absence of food or ii) food quality, where algae of high or low nutrient (phosphorus) content were offered in distinct patches. Individuals of both Daphnia species chose tubes containing food patches and D. galeata x hyalina also showed a preference towards food patches of high nutrient content. We discuss how the described equipment complements other behavioral approaches providing a useful tool to understand animal foraging decisions in environments with heterogeneous resource distributions.}, language = {en} } @article{TikhonenkoMagidsonGraefetal.2013, author = {Tikhonenko, Irina and Magidson, Valentin and Gr{\"a}f, Ralph and Khodjakov, Alexey and Koonce, Michael P.}, title = {A kinesin-mediated mechanism that couples centrosomes to nuclei}, series = {Cellular and molecular life sciences}, volume = {70}, journal = {Cellular and molecular life sciences}, number = {7}, publisher = {Springer}, address = {Basel}, issn = {1420-682X}, doi = {10.1007/s00018-012-1205-0}, pages = {1285 -- 1296}, year = {2013}, abstract = {The M-type kinesin isoform, Kif9, has recently been implicated in maintaining a physical connection between the centrosome and nucleus in Dictyostelium discoideum. However, the mechanism by which Kif9 functions to link these two organelles remains obscure. Here we demonstrate that the Kif9 protein is localized to the nuclear envelope and is concentrated in the region underlying the centrosome point of attachment. Nuclear anchorage appears mediated through a specialized transmembrane domain located in the carboxyl terminus. Kif9 interacts with microtubules in in vitro binding assays and effects an endwise depolymerization of the polymer. These results suggest a model whereby Kif9 is anchored to the nucleus and generates a pulling force that reels the centrosome up against the nucleus. This is a novel activity for a kinesin motor, one important for progression of cells into mitosis and to ensure centrosome-nuclear parity in a multinuclear environment.}, language = {en} } @phdthesis{Wang2013, author = {Wang, Ting}, title = {A novel R2R3 MYB-like transcription factor regulates ABA mediated stress response and leaf growth in Arabidopsis}, address = {Potsdam}, pages = {102 S.}, year = {2013}, language = {en} } @article{FiorentinoManganelliGiustietal.2013, author = {Fiorentino, V. and Manganelli, Giuseppe and Giusti, Folco and Tiedemann, Ralph and Ketmaier, Valerino}, title = {A question of time the land snail Murella muralis (Gastropoda: Pulmonata) reveals constraints on past ecological speciation}, series = {Molecular ecology}, volume = {22}, journal = {Molecular ecology}, number = {1}, publisher = {Wiley-Blackwell}, address = {Hoboken}, issn = {0962-1083}, doi = {10.1111/mec.12107}, pages = {170 -- 186}, year = {2013}, abstract = {The lively debate about speciation currently focuses on the relative importance of factors driving population differentiation. While many studies are increasingly producing results on the importance of selection, little is known about the interaction between drift and selection. Moreover, there is still little knowledge on the spatial-temporal scales at which speciation occurs, that is, arrangement of habitat patches, abruptness of habitat transitions, climate and habitat changes interacting with selective forces. To investigate these questions, we quantified variation on a fine geographical scale analysing morphological (shell) and genetic data sets coupled with environmental data in the land snail Murella muralis, endemic to the Mediterranean island of Sicily. Analysis of a fragment of the mitochondrial DNA cytochrome oxidase I gene (COI) and eight nuclear microsatellite loci showed that genetic variation is highly structured at a very fine spatial scale by local palaeogeographical events and historical population dynamics. Molecular clock estimates, calibrated here specifically for Tyrrhenian land snails, provided a framework of palaeogeographical events responsible for the observed geographical variations and migration routes. Finally, we showed for the first time well-documented lines of evidence of selection in the past, which explains divergence of land snail shell shapes. We suggest that time and palaeogeographical history acted as constraints in the progress along the ecological speciation continuum. Our study shows that testing for correlation among palaeogeography, morphology and genetic data on a fine geographical scale provides information fundamental for a detailed understanding of ecological speciation processes.}, language = {en} } @article{BrothersHiltAttermeyeretal.2013, author = {Brothers, Soren M. and Hilt, Sabine and Attermeyer, Katrin and Grossart, Hans-Peter and Kosten, Sarian and Lischke, Betty and Mehner, Thomas and Meyer, Nils and Scharnweber, Inga Kristin and K{\"o}hler, Jan}, title = {A regime shift from macrophyte to phytoplankton dominance enhances carbon burial in a shallow, eutrophic lake}, series = {Ecosphere : the magazine of the International Ecology University}, volume = {4}, journal = {Ecosphere : the magazine of the International Ecology University}, number = {11}, publisher = {Wiley}, address = {Washington}, issn = {2150-8925}, doi = {10.1890/ES13-00247.1}, pages = {17}, year = {2013}, abstract = {Ecological regime shifts and carbon cycling in aquatic systems have both been subject to increasing attention in recent years, yet the direct connection between these topics has remained poorly understood. A four-fold increase in sedimentation rates was observed within the past 50 years in a shallow eutrophic lake with no surface in-or outflows. This change coincided with an ecological regime shift involving the complete loss of submerged macrophytes, leading to a more turbid, phytoplankton-dominated state. To determine whether the increase in carbon (C) burial resulted from a comprehensive transformation of C cycling pathways in parallel to this regime shift, we compared the annual C balances (mass balance and ecosystem budget) of this turbid lake to a similar nearby lake with submerged macrophytes, a higher transparency, and similar nutrient concentrations. C balances indicated that roughly 80\% of the C input was permanently buried in the turbid lake sediments, compared to 40\% in the clearer macrophyte-dominated lake. This was due to a higher measured C burial efficiency in the turbid lake, which could be explained by lower benthic C mineralization rates. These lower mineralization rates were associated with a decrease in benthic oxygen availability coinciding with the loss of submerged macrophytes. In contrast to previous assumptions that a regime shift to phytoplankton dominance decreases lake heterotrophy by boosting whole-lake primary production, our results suggest that an equivalent net metabolic shift may also result from lower C mineralization rates in a shallow, turbid lake. The widespread occurrence of such shifts may thus fundamentally alter the role of shallow lakes in the global C cycle, away from channeling terrestrial C to the atmosphere and towards burying an increasing amount of C.}, language = {en} } @phdthesis{Zauber2013, author = {Zauber, Henrik}, title = {A systems biology driven approach for analyzing lipid protein interactions in sterol biosynthesis mutants}, address = {Potsdam}, pages = {126 S.}, year = {2013}, language = {en} } @article{GulbinsPalmadaReicheletal.2013, author = {Gulbins, Erich and Palmada, Monica and Reichel, Martin and Lueth, Anja and Boehmer, Christoph and Amato, Davide and Mueller, Christian P. and Tischbirek, Carsten H. and Groemer, Teja W. and Tabatabai, Ghazaleh and Becker, Katrin Anne and Tripal, Philipp and Staedtler, Sven and Ackermann, Teresa F. and van Brederode, Johannes and Alzheimer, Christian and Weller, Michael and Lang, Undine E. and Kleuser, Burkhard and Grassme, Heike and Kornhuber, Johannes}, title = {Acid sphingomyelinase-ceramide system mediates effects of antidepressant drugs}, series = {Nature medicine}, volume = {19}, journal = {Nature medicine}, number = {7}, publisher = {Nature Publ. Group}, address = {New York}, issn = {1078-8956}, doi = {10.1038/nm.3214}, pages = {934 -- +}, year = {2013}, abstract = {Major depression is a highly prevalent severe mood disorder that is treated with antidepressants. The molecular targets of antidepressants require definition. We investigated the role of the acid sphingomyelinase (Asm)-ceramide system as a target for antidepressants. Therapeutic concentrations of the antidepressants amitriptyline and fluoxetine reduced Asm activity and ceramide concentrations in the hippocampus, increased neuronal proliferation, maturation and survival and improved behavior in mouse models of stress-induced depression. Genetic Asm deficiency abrogated these effects. Mice overexpressing Asm, heterozygous for acid ceramidase, treated with blockers of ceramide metabolism or directly injected with C16 ceramide in the hippocampus had higher ceramide concentrations and lower rates of neuronal proliferation, maturation and survival compared with controls and showed depression-like behavior even in the absence of stress. The decrease of ceramide abundance achieved by antidepressant-mediated inhibition of Asm normalized these effects. Lowering ceramide abundance may thus be a central goal for the future development of antidepressants.}, language = {en} } @article{FechnerBaumannWalz2013, author = {Fechner, Lennart and Baumann, Otto and Walz, Bernd}, title = {Activation of the cyclic AMP pathway promotes serotonin-induced Ca2+ oscillations in salivary glands of the blowfly Calliphora vicina}, series = {Cell calcium}, volume = {53}, journal = {Cell calcium}, number = {2}, publisher = {Churchill Livingstone}, address = {Edinburgh}, issn = {0143-4160}, doi = {10.1016/j.ceca.2012.10.004}, pages = {94 -- 101}, year = {2013}, abstract = {Ca2+ and cAMP signalling pathways interact in a complex manner at multiple sites. This crosstalk fine-tunes the spatiotemporal patterns of Ca2+ and cAMP signals. In salivary glands of the blowfly Calliphora vicina fluid secretion is stimulated by serotonin (5-hydroxytryptamine, 5-HT) via activation of two different 5-HT receptors coupled to the InsP(3)/Ca2+ (Cv5-HT2 alpha) or the cAMP pathway (Cv5-HT7), respectively. We have shown recently in permeabilized gland cells that cAMP sensitizes InsP(3)-induced Ca2+ release to InsP(3). Here we study the effects of the CAMP signalling pathway on 5-HT-induced oscillations in transepithelial potential (TEP) and in intracellular [Ca2+]. We show: (1) Blocking the activation of the cAMP pathway by cinanserin suppresses the generation of TEP and Ca2+ oscillations, (2) application of 8-CPT-cAMP in the presence of cinanserin restores 5-HT-induced TEP and Ca2+ oscillations, (3) 8-CPT-cAMP sensitizes the InsP(3)/Ca2+ signalling pathway to 5-HT and the Cv5-HT2 alpha, receptor agonist 5-MeOT, (4) 8-CPT-cAMP induces Ca2+ oscillations in cells loaded with subthreshold concentrations of InsP(3), (5) inhibition of protein kinase A by H-89 abolishes 5-HT-induced TEP and Ca2+ spiking and mimics the effect of cinanserin. These results suggest that activation of the cyclic AMP pathway promotes the generation of 5-HT-induced Ca2+ oscillations in blowfly salivary glands.}, language = {en} } @phdthesis{Freudenberger2013, author = {Freudenberger, Lisa}, title = {Adaptation of nature conservation to global change: an ecosystem-based approach to priority-setting}, address = {Potsdam}, pages = {253 S.}, year = {2013}, language = {en} } @article{AndresGohlkeBroekeretal.2013, author = {Andres, Dorothee and Gohlke, Ulrich and Br{\"o}ker, Nina Kristin and Schulze, Stefan and Rabsch, Wolfgang and Heinemann, Udo and Barbirz, Stefanie and Seckler, Robert}, title = {An essential serotype recognition pocket on phage P22 tailspike protein forces Salmonella enterica serovar Paratyphi A O-antigen fragments to bind as nonsolution conformers}, series = {Glycobiology}, volume = {23}, journal = {Glycobiology}, number = {4}, publisher = {Oxford Univ. Press}, address = {Cary}, issn = {0959-6658}, doi = {10.1093/glycob/cws224}, pages = {486 -- 494}, year = {2013}, abstract = {Bacteriophage P22 recognizes O-antigen polysaccharides of Salmonella enterica subsp. enterica (S.) with its tailspike protein (TSP). In the serovars S. Typhimurium, S. Enteritidis, and S. Paratyphi A, the tetrasaccharide repeat units of the respective O-antigens consist of an identical main chain trisaccharide but different 3,6-dideoxyhexose substituents. Here, the epimers abequose, tyvelose and paratose determine the specific serotype. P22 TSP recognizes O-antigen octasaccharides in an extended binding site with a single 3,6-dideoxyhexose binding pocket. We have isolated S. Paratyphi A octasaccharides which were not available previously and determined the crystal structure of their complex with P22 TSP. We discuss our data together with crystal structures of complexes with S. Typhimurium and S. Enteritidis octasaccharides determined earlier. Isothermal titration calorimetry showed that S. Paratyphi A octasaccharide binds P22 TSP less tightly, with a difference in binding free energy of similar to 7 kJ mol(-1) at 20 degrees C compared with S. Typhimurium and S. Enteritidis octasaccharides. Individual protein-carbohydrate contacts were probed by amino acid replacements showing that the dideoxyhexose pocket contributes to binding of all three serotypes. However, S. Paratyphi A octasaccharides bind in a conformation with an energetically unfavorable phi/epsilon glycosidic bond angle combination. In contrast, octasaccharides from the other serotypes bind as solution-like conformers. Two water molecules are conserved in all P22 TSP complexes with octasaccharides of different serotypes. They line the dideoxyhexose binding pocket and force the S. Paratyphi A octasaccharides to bind as nonsolution conformers. This emphasizes the role of solvent as part of carbohydrate binding sites.}, language = {en} } @article{NguyenSchippersGoniRamosetal.2013, author = {Nguyen, Hung M. and Schippers, Jos H. M. and Goni-Ramos, Oscar and Christoph, Mathias P. and Dortay, Hakan and van der Hoorn, Renier A. L. and M{\"u}ller-R{\"o}ber, Bernd}, title = {An upstream regulator of the 26S proteasome modulates organ size in Arabidopsis thaliana}, series = {The plant journal}, volume = {74}, journal = {The plant journal}, number = {1}, publisher = {Wiley-Blackwell}, address = {Hoboken}, issn = {0960-7412}, doi = {10.1111/tpj.12097}, pages = {25 -- 36}, year = {2013}, abstract = {In both animal and plant kingdoms, body size is a fundamental but still poorly understood attribute of biological systems. Here we report that the Arabidopsis NAC transcription factor Regulator of Proteasomal Gene Expression' (RPX) controls leaf size by positively modulating proteasome activity. We further show that the cis-element recognized by RPX is evolutionarily conserved between higher plant species. Upon over-expression of RPX, plants exhibit reduced growth, which may be reversed by a low concentration of the pharmacological proteasome inhibitor MG132. These data suggest that the rate of protein turnover during growth is a critical parameter for determining final organ size.}, language = {en} } @phdthesis{Bortfeld2013, author = {Bortfeld, Silvia}, title = {Analysis of Medicago truncatula transcription factors involved in the arbuscular mycorrhizal symbiosis}, url = {http://nbn-resolving.de/urn:nbn:de:kobv:517-opus-70664}, school = {Universit{\"a}t Potsdam}, year = {2013}, abstract = {For the first time the transcriptional reprogramming of distinct root cortex cells during the arbuscular mycorrhizal (AM) symbiosis was investigated by combining Laser Capture Mirodissection and Affymetrix GeneChip® Medicago genome array hybridization. The establishment of cryosections facilitated the isolation of high quality RNA in sufficient amounts from three different cortical cell types. The transcript profiles of arbuscule-containing cells (arb cells), non-arbuscule-containing cells (nac cells) of Rhizophagus irregularis inoculated Medicago truncatula roots and cortex cells of non-inoculated roots (cor) were successfully explored. The data gave new insights in the symbiosis-related cellular reorganization processes and indicated that already nac cells seem to be prepared for the upcoming fungal colonization. The mycorrhizal- and phosphate-dependent transcription of a GRAS TF family member (MtGras8) was detected in arb cells and mycorrhizal roots. MtGRAS shares a high sequence similarity to a GRAS TF suggested to be involved in the fungal colonization processes (MtRAM1). The function of MtGras8 was unraveled upon RNA interference- (RNAi-) mediated gene silencing. An AM symbiosis-dependent expression of a RNAi construct (MtPt4pro::gras8-RNAi) revealed a successful gene silencing of MtGras8 leading to a reduced arbuscule abundance and a higher proportion of deformed arbuscules in root with reduced transcript levels. Accordingly, MtGras8 might control the arbuscule development and life-time. The targeting of MtGras8 by the phosphate-dependent regulated miRNA5204* was discovered previously (Devers et al., 2011). Since miRNA5204* is known to be affected by phosphate, the posttranscriptional regulation might represent a link between phosphate signaling and arbuscule development. In this work, the posttranscriptional regulation was confirmed by mis-expression of miRNA5204* in M. truncatula roots. The miRNA-mediated gene silencing affects the MtGras8 transcript abundance only in the first two weeks of the AM symbiosis and the mis-expression lines seem to mimic the phenotype of MtGras8-RNAi lines. Additionally, MtGRAS8 seems to form heterodimers with NSP2 and RAM1, which are known to be key regulators of the fungal colonization process (Hirsch et al., 2009; Gobbato et al., 2012). These data indicate that MtGras8 and miRNA5204* are linked to the sym pathway and regulate the arbuscule development in phosphate-dependent manner.}, language = {en} } @article{HillLeowBleidornetal.2013, author = {Hill, Natascha and Leow, Alexander and Bleidorn, Christoph and Groth, Detlef and Tiedemann, Ralph and Selbig, Joachim and Hartmann, Stefanie}, title = {Analysis of phylogenetic signal in protostomial intron patterns using Mutual Information}, series = {Theory in biosciences}, volume = {132}, journal = {Theory in biosciences}, number = {2}, publisher = {Springer}, address = {New York}, issn = {1431-7613}, doi = {10.1007/s12064-012-0173-0}, pages = {93 -- 104}, year = {2013}, abstract = {Many deep evolutionary divergences still remain unresolved, such as those among major taxa of the Lophotrochozoa. As alternative phylogenetic markers, the intron-exon structure of eukaryotic genomes and the patterns of absence and presence of spliceosomal introns appear to be promising. However, given the potential homoplasy of intron presence, the phylogenetic analysis of this data using standard evolutionary approaches has remained a challenge. Here, we used Mutual Information (MI) to estimate the phylogeny of Protostomia using gene structure data, and we compared these results with those obtained with Dollo Parsimony. Using full genome sequences from nine Metazoa, we identified 447 groups of orthologous sequences with 21,732 introns in 4,870 unique intron positions. We determined the shared absence and presence of introns in the corresponding sequence alignments and have made this data available in "IntronBase", a web-accessible and downloadable SQLite database. Our results obtained using Dollo Parsimony are obviously misled through systematic errors that arise from multiple intron loss events, but extensive filtering of data improved the quality of the estimated phylogenies. Mutual Information, in contrast, performs better with larger datasets, but at the same time it requires a complete data set, which is difficult to obtain for orthologs from a large number of taxa. Nevertheless, Mutual Information-based distances proved to be useful in analyzing this kind of data, also because the estimation of MI-based distances is independent of evolutionary models and therefore no pre-definitions of ancestral and derived character states are necessary.}, language = {en} } @article{BaselHarmsPrechtl2013, author = {Basel, Nicolai and Harms, Ute and Prechtl, Helmut}, title = {Analysis of students' arguments on evolutionary theory}, series = {Journal of biological education}, volume = {47}, journal = {Journal of biological education}, number = {4}, publisher = {Routledge, Taylor \& Francis Group}, address = {Abingdon}, issn = {0021-9266}, doi = {10.1080/00219266.2013.799078}, pages = {192 -- 199}, year = {2013}, abstract = {A qualitative exploratory study was conducted to reveal students' argumentation skills in the context of the topic of evolution. Transcripts from problem-centred interviews on secondary students' beliefs about evolutionary processes of adaptation were analysed using a content analysis approach. For this purpose two categorical systems were deductively developed: one addressing the complexity of students' arguments, the other focusing on students' use of argumentation schemes. Subsequently, the categorical systems were inductively elaborated upon the basis of the analysed material showing a satisfactory inter-rater reliability. Regarding the arguments' complexity, students produced mainly single claims or claims with a single justification consisting of either data or warrants. With regard to argumentation schemes students drew their arguments mainly using causal schemes, analogies, or illustrative examples. Results are discussed in light of possible implications for teaching evolutionary theory using classroom argumentation.}, language = {en} } @article{BadalyanYogaSchwuchowetal.2013, author = {Badalyan, Artavazd and Yoga, Etienne Galemou and Schwuchow, Viola and P{\"o}ller, Sascha and Schuhmann, Wolfgang and Leimk{\"u}hler, Silke and Wollenberger, Ursula}, title = {Analysis of the interaction of the molybdenum hydroxylase PaoABC from Escherichia coli with positively and negatively charged metal complexes}, series = {Electrochemistry communications : an international journal dedicated to rapid publications in electrochemistry}, volume = {37}, journal = {Electrochemistry communications : an international journal dedicated to rapid publications in electrochemistry}, publisher = {Elsevier}, address = {New York}, issn = {1388-2481}, doi = {10.1016/j.elecom.2013.09.017}, pages = {5 -- 7}, year = {2013}, abstract = {An unusual behavior of the periplasmic aldehyde oxidoreductase (PaoABC) from Escherichia coil has been observed from electrochemical investigations of the enzyme catalyzed oxidation of aromatic aldehydes with different mediators under different conditions of ionic strength. The enzyme has similarity to other molybdoenzymes of the xanthine oxidase family, but the catalytic behavior turned out to be very different. Under steady state conditions the turnover of PaoABC is maximal at pH 4 for the negatively charged ferricyanide and at pH 9 for a positively charged osmium complex. Stopped-flow kinetic measurements of the catalytic half reaction showed that oxidation of benzaldehyde proceeds also above pH 7. Thus, benzaldehyde oxidation can proceed under acidic and basic conditions using this enzyme, a property which has not been described before for molybdenum hydroxylases. It is also suggested that the electron transfer with artificial electron acceptors and PaoABC can proceed at different protein sites and depends on the nature of the electron acceptor in addition to the ionic strength. (C) 2013 Elsevier B.V. All rights reserved.}, language = {en} } @article{LiangHeinrichHelleetal.2013, author = {Liang, Wei and Heinrich, Ingo and Helle, Gerhard and Linan, Isabel Dorado and Heinken, Thilo}, title = {Applying CLSM to increment core surfaces for histometric analyses a novel advance in quantitative wood anatomy}, series = {Dendrochronologia : an interdisciplinary journal of tree-ring science}, volume = {31}, journal = {Dendrochronologia : an interdisciplinary journal of tree-ring science}, number = {2}, publisher = {Elsevier}, address = {Jena}, issn = {1125-7865}, doi = {10.1016/j.dendro.2012.09.002}, pages = {140 -- 145}, year = {2013}, abstract = {A novel procedure has been developed to conduct cell structure measurements on increment core samples of conifers. The procedure combines readily available hardware and software equipment. The essential part of the procedure is the application of a confocal laser scanning microscope (CLSM) which captures images directly from increment cores surfaced with the advanced WSL core-microtome. Cell wall and lumen are displayed with a strong contrast due to the monochrome black and green nature of the images. Consecutive images are merged into long images representing entire increment cores which are then analysed for cell structures in suitable software.}, language = {en} } @phdthesis{Doering2013, author = {D{\"o}ring, Anett}, title = {Arabidopsis thaliana endomembrane / Golgi V-ATPase activity regulates the cellulose synthase life-time at, and the delivery to, the plasma membrane}, address = {Potsdam}, pages = {116 S.}, year = {2013}, language = {en} } @article{SchradeScheffler2013, author = {Schrade, Lisa and Scheffler, Christiane}, title = {Assessing the applicability of the digital laser rangefinder GLM Professional (R) Bosch 250 VF for anthropometric field studies}, series = {Journal of biological and clinical anthropology : Anthropologischer Anzeiger ; Mitteilungsorgan der Gesellschaft f{\"u}r Anthropologie}, volume = {70}, journal = {Journal of biological and clinical anthropology : Anthropologischer Anzeiger ; Mitteilungsorgan der Gesellschaft f{\"u}r Anthropologie}, number = {2}, publisher = {Schweizerbart}, address = {Stuttgart}, issn = {0003-5548}, doi = {10.1127/0003-5548/2013/0223}, pages = {137 -- 145}, year = {2013}, abstract = {The digital laser rangefinder GLM Professional (R) BOSCH 250 VF was tested as a modified preproduction model with regard to its applicability of quantifying humans' height. The aim of this investigation was to determine and evaluate the instrument's precision, as well as its manageability within anthropometric field studies. Data collected by the digital laser rangefinder did not show a significant difference to data of control by an anthropometer. Furthermore, more than 96\% of the difference values are located within area of agreement. Nevertheless, the GLM Professional (R) is a highly sensitive instrument and mean SD within threefold data acquisition is twice as high as SD resulting from data collection by an anthropometer. However, due to the minimal percentage differences within data acquisition and compared to the standard method, the GLM Professional (R) is proved to be a reliable instrument and to be highly applicable for anthropometric field studies. Furthermore, due to its excellent manageability and compact size, the GLM Professional (R) shows a very good applicability even for less trained anthropometrists and thus ameliorates the possibilities of collecting reliable data within anthropometric field studies.}, language = {en} } @article{SchradeScheffler2013, author = {Schrade, Lisa and Scheffler, Christiane}, title = {Assessing the applicability of the digital laser rangefinder GLM Professional Bosch 250 VF for anthropometric field studies}, year = {2013}, language = {en} } @article{EigemannHiltSalkaetal.2013, author = {Eigemann, Falk and Hilt, Sabine and Salka, Ivette and Grossart, Hans-Peter}, title = {Bacterial community composition associated with freshwater algae species specificity vs. dependency on environmental conditions and source community}, series = {FEMS microbiology ecology}, volume = {83}, journal = {FEMS microbiology ecology}, number = {3}, publisher = {Wiley-Blackwell}, address = {Hoboken}, issn = {0168-6496}, doi = {10.1111/1574-6941.12022}, pages = {650 -- 663}, year = {2013}, abstract = {We studied bacterial associations with the green alga Desmodesmus armatus and the diatom Stephanodiscus minutulus under changing environmental conditions and bacterial source communities, to evaluate whether bacteriaalgae associations are species-specific or more generalized and determined by external factors. Axenic and xenic algae were incubated in situ with and without allelopathically active macrophytes, and in the laboratory with sterile and nonsterile lake water and an allelochemical, tannic acid (TA). Bacterial community composition (BCC) of algae-associated bacteria was analyzed by denaturing gradient gel electrophoresis (DGGE), nonmetric multidimensional scaling, cluster analyses, and sequencing of DGGE bands. BCC of xenic algal cultures of both species were not significantly affected by changes in their environment or bacterial source community, except in the case of TA additions. Species-specific interactions therefore appear to overrule the effects of environmental conditions and source communities. The BCC of xenic and axenic D.armatus cultures subjected to in situ bacterial colonization, however, had lower similarities (ca.55\%), indicating that bacterial precolonization is a strong factor for bacteriaalgae associations irrespective of environmental conditions and source community. Our findings emphasize the ecological importance of species-specific bacteriaalgae associations with important repercussions for other processes, such as the remineralization of nutrients, and organic matter dynamics.}, language = {en} } @article{RadchukJohstGroeneveldetal.2013, author = {Radchuk, Viktoriia and Johst, Karin and Gr{\"o}neveld, Juergen and Grimm, Volker and Schtickzelle, Nicolas}, title = {Behind the scenes of population viability modeling predicting butterfly metapopulation dynamics under climate change}, series = {Ecological modelling : international journal on ecological modelling and engineering and systems ecolog}, volume = {259}, journal = {Ecological modelling : international journal on ecological modelling and engineering and systems ecolog}, number = {2}, publisher = {Elsevier}, address = {Amsterdam}, issn = {0304-3800}, doi = {10.1016/j.ecolmodel.2013.03.014}, pages = {62 -- 73}, year = {2013}, abstract = {Studies explaining the choice of model structure for population viability analysis (PVA) are rare and no such study exists for butterfly species, a focal group for conservation. Here, we describe in detail the development of a model to predict population viability of a glacial relict butterfly species, Boloria eunomia, under climate change. We compared four alternative formulations of an individual-based model, differing in the environmental factors acting on the survival of immature life stages: temperature (only temperature impact), weather (temperature, precipitation, and sunshine), temperature and parasitism, and weather and parasitism. Following pattern-oriented modeling, four observed patterns were used to contrast these models: one qualitative (response of population size to habitat parameters) and three quantitative ones describing population dynamics during eight years (mean and variability of population size, and magnitude of the temporal autocorrelation in yearly population growth rates). The four model formulations were not equally able to depict population dynamics under current environmental conditions; the model including only temperature was selected as the most parsimonious model sufficiently well reproducing the empirical patterns. We used all four model formulations to test a range of climate change scenarios that were characterized by changes in both mean and variability of the weather variables. All models predicted adverse effects of climate change and resulted in the same ranking of mean climate change scenarios. However, models differed in their absolute values of population viability measures, underlining the need to explicitly choose the most appropriate model formulation and avoid arbitrary usage of environmental drivers in a model. We conclude that further applications of pattern-oriented modeling to butterfly and other species are likely to help in identifying the key factors impacting the viability of certain taxa, which, ultimately, will aid and speed up informed management decisions for endangered species under climate change.}, language = {en} } @article{SeifanSeifanSchiffersetal.2013, author = {Seifan, Merav and Seifan, Tal and Schiffers, Katja and Jeltsch, Florian and Tielboerger, Katja}, title = {Beyond the competition-colonization trade-off - linking multiple trait response to disturbance characteristics}, series = {The American naturalist : a bi-monthly journal devoted to the advancement and correlation of the biological sciences}, volume = {181}, journal = {The American naturalist : a bi-monthly journal devoted to the advancement and correlation of the biological sciences}, number = {2}, publisher = {Univ. of Chicago Press}, address = {Chicago}, issn = {0003-0147}, doi = {10.1086/668844}, pages = {151 -- 160}, year = {2013}, abstract = {Disturbances' role in shaping communities is well documented but highly disputed. We suggest replacing the overused two-trait trade-off approach with a functional group scheme, constructed from combinations of four key traits that represent four classes of species' responses to disturbances. Using model results and field observations from sites affected by two highly different disturbances, we demonstrated that popular dichotomous trade-offs are not sufficient to explain community dynamics, even if some emerge under certain conditions. Without disturbances, competition was only sufficient to predict species survival but not relative success, which required some escape mechanism (e.g., long-term dormancy). With highly predictable and large-scale disturbances, successful species showed a combination of high individual tolerance to disturbance and, more surprisingly, high competitive ability. When disturbances were less predictable, high individual tolerance and long-term seed dormancy were favored, due to higher environmental uncertainty. Our study demonstrates that theories relying on a small number of predefined trade-offs among traits (e.g., competition-colonization trade-off) may lead to unrealistic results. We suggest that the understanding of disturbance-community relationships can be significantly improved by employing sets of relevant trait assemblies instead of the currently common approach in which trade-offs are assumed in advance.}, language = {en} } @article{CarregariFlorianoRodriguesSimionietal.2013, author = {Carregari, Victor Corasolla and Floriano, Rafael Stuani and Rodrigues-Simioni, Lea and Winck, Flavia V. and Baldasso, Paulo Aparecido and Ponce-Soto, Luis Alberto and Marangoni, Sergio}, title = {Biochemical, Pharmacological, and Structural Characterization of New Basic PLA(2) Bbil-TX from Bothriopsis bilineata Snake Venom}, series = {BioMed research international}, journal = {BioMed research international}, publisher = {Hindawi Publishing Corp.}, address = {New York}, issn = {2314-6133}, doi = {10.1155/2013/612649}, pages = {12}, year = {2013}, abstract = {Bbil-TX, a PLA(2), was purified from Bothriopsis bilineata snake venom after only one chromatographic step using RP-HPLC on mu-Bondapak C-18 column. A molecular mass of 14243.8 Da was confirmed by -Tof ltima API ESI/ MS (TOF MS mode) mass spectrometry. The partial protein sequence obtained was then submitted to BLASTp, with the search restricted to PLA(2) from snakes and shows high identity values when compared to other PLA(2)s. PLA(2) activity was presented in the presence of a synthetic substrate and showed a minimum sigmoidal behavior, reaching its maximal activity at pH 8.0 and 25-37 degrees C. Maximum PLA(2) activity required Ca2+ and in the presence of Cd2+, Zn2+, Mn2+, and Mg2+ it was reduced in the presence or absence of Ca2+. Crotapotin from Crotalus durissus cascavella rattlesnake venom and antihemorrhagic factor DA2-II from Didelphis albiventris opossum sera under optimal conditions significantly inhibit the enzymatic activity. Bbil-TX induces myonecrosis in mice. The fraction does not show a significant cytotoxic activity in myotubes and myoblasts (C2C12). The infiammatory events induced in the serum of mice by Bbil-TX isolated from Bothriopsis bilineata snake venom were investigated. An increase in vascular permeability and in the levels of TNF-a, IL-6, and IL-1 was was induced. Since Bbil-TX exerts a stronger proinfiammatory effect, the phospholipid hydrolysis may be relevant for these phenomena.}, language = {en} } @phdthesis{Sandmann2013, author = {Sandmann, Michael}, title = {Biochemische und cytologische Marker der Zellentwicklung synchronisierter St{\"a}mme con Chlamydomonas reinhardtii}, address = {Potsdam}, pages = {121 S.}, year = {2013}, language = {de} } @phdthesis{Badalyan2013, author = {Badalyan, Artavazd}, title = {Bioelectrochemistry of molybdenum hydroxylases : aldehyde oxidoreductase PaoABC from escherichia coli and xanthine dehydrogenase from rhodobacter capsulatus}, address = {Potsdam}, pages = {117 S.}, year = {2013}, language = {en} } @article{Scheffler2013, author = {Scheffler, Christiane}, title = {Biological age}, series = {Auxology : Studying Human Growth and Development}, journal = {Auxology : Studying Human Growth and Development}, editor = {Hermanussen, Michael}, publisher = {Schweizerbart Science Publishers}, address = {Stuttgart}, isbn = {978-3-510-65278-5}, pages = {44 -- 47}, year = {2013}, language = {en} } @unpublished{CierjacksKowarikJoshietal.2013, author = {Cierjacks, Arne and Kowarik, Ingo and Joshi, Jasmin Radha and Hempel, Stefan and Ristow, Michael and von der Lippe, Moritz and Weber, Ewald}, title = {Biological flora of the british isles: robinia pseudoacacia}, series = {The journal of ecology}, volume = {101}, journal = {The journal of ecology}, number = {6}, publisher = {Wiley-Blackwell}, address = {Hoboken}, issn = {0022-0477}, doi = {10.1111/1365-2745.12162}, pages = {1623 -- 1640}, year = {2013}, abstract = {This account presents information on all aspects of the biology of Robinia pseudoacacia L. that are relevant to understanding its ecological characteristics and behaviour. The main topics are presented within the standard framework of the Biological Flora of the British Isles: distribution, habitat, communities, responses to biotic factors, responses to environment, structure and physiology, phenology, floral and seed characters, herbivores and disease, and history and conservation.Robinia pseudoacacia, false acacia or black locust, is a deciduous, broad-leaved tree native to North America. The medium-sized, fast-growing tree is armed with spines, and extensively suckering. It has become naturalized in grassland, semi-natural woodlands and urban habitats. The tree is common in the south of the British Isles and in many other regions of Europe.Robinia pseudoacacia is a light-demanding pioneer species, which occurs primarily in disturbed sites on fertile to poor soils. The tree does not tolerate wet or compacted soils. In contrast to its native range, where it rapidly colonizes forest gaps and is replaced after 15-30years by more competitive tree species, populations in the secondary range can persist for a longer time, probably due to release from natural enemies.Robinia pseudoacacia reproduces sexually, and asexually by underground runners. Disturbance favours clonal growth and leads to an increase in the number of ramets. Mechanical stem damage and fires also lead to increased clonal recruitment. The tree benefits from di-nitrogen fixation associated with symbiotic rhizobia in root nodules. Estimated symbiotic nitrogen fixation rates range widely from 23 to 300kgha(-1)year(-1). The nitrogen becomes available to other plants mainly by the rapid decay of nitrogen-rich leaves.Robinia pseudoacacia is host to a wide range of fungi both in the native and introduced ranges. Megaherbivores are of minor significance in Europe but browsing by ungulates occurs in the native range. Among insects, the North American black locust gall midge (Obolodiplosis robiniae) is specific to Robinia and is spreading rapidly throughout Europe. In parts of Europe, Robinia pseudoacacia is considered an invasive non-indigenous plant and the tree is controlled. Negative impacts include shading and changes of soil conditions as a result of nitrogen fixation.}, language = {en} } @article{HechavarriaMaciasVateretal.2013, author = {Hechavarria, Julio C. and Macias, Silvio and Vater, Marianne and Voss, Cornelia and Mora, Emanuel C. and Kossl, Manfred}, title = {Blurry topography for precise target-distance computations in the auditory cortex of echolocating bats}, series = {Nature Communications}, volume = {4}, journal = {Nature Communications}, number = {10}, publisher = {Nature Publ. Group}, address = {London}, issn = {2041-1723}, doi = {10.1038/ncomms3587}, pages = {11}, year = {2013}, abstract = {Echolocating bats use the time from biosonar pulse emission to the arrival of echo (defined as echo delay) to calculate the space depth of targets. In the dorsal auditory cortex of several species, neurons that encode increasing echo delays are organized rostrocaudally in a topographic arrangement defined as chronotopy. Precise chronotopy could be important for precise target-distance computations. Here we show that in the cortex of three echolocating bat species (Pteronotus quadridens, Pteronotus parnellii and Carollia perspicillata), chronotopy is not precise but blurry. In all three species, neurons throughout the chronotopic map are driven by short echo delays that indicate the presence of close targets and the robustness of map organization depends on the parameter of the receptive field used to characterize neuronal tuning. The timing of cortical responses (latency and duration) provides a binding code that could be important for assembling acoustic scenes using echo delay information from objects with different space depths.}, language = {en} } @article{Scheffler2013, author = {Scheffler, Christiane}, title = {Body composition}, series = {Auxology : Studying Human Growth and Development}, journal = {Auxology : Studying Human Growth and Development}, editor = {Hermanussen, Michael}, publisher = {Schweizerbart Science Publishers}, address = {Stuttgart}, isbn = {978-3-510-65278-5}, pages = {30 -- 31}, year = {2013}, language = {en} } @phdthesis{Rietsch2013, author = {Rietsch, Katrin}, title = {Body composition especially external skeletal robustness in association with physical activity and recreation in pre-pubertal children : a national and international investigation}, url = {http://nbn-resolving.de/urn:nbn:de:kobv:517-opus-66913}, school = {Universit{\"a}t Potsdam}, year = {2013}, abstract = {In children the way of life, nutrition and recreation changed in recent years and as a consequence body composition shifted as well. It is established that overweight belongs to a global problem. In addition, German children exhibit a less robust skeleton than ten years ago. These developments may elevate the risk of cardiovascular diseases and skeletal modifications. Heredity and environmental factors as nutrition, socioeconomic status, physical activity and inactivity influence fat accumulation and the skeletal system. Based on these negative developments associations between type of body shape, skeletal measures and physical activity; relations between external skeletal robustness, physical activity and inactivity, BMI and body fat and also the progress of body composition especially external skeletal robustness in comparison in Russian and German children were investigated. In a cross-sectional study 691 German boys and girls aged 6 to 10 years were examined. Anthropometric measurements were taken and questionnaires about physical activity and inactivity were answered by parents. Additionally, pedometers were worn to determinate the physical activity in children. To compare the body composition in Russian and German children data from the years 2000 and 2010 were used. The study has shown that pyknomorphic individuals exhibit the highest external skeletal robustness and leptomorphic ones the lowest. Leptomorphic children may have a higher risk for bone diseases in adulthood. Pyknomorphic boys are more physically active by tendency. This is assessed as positive because pyknomorphic types display the highest BMI and body fat. Results showed that physical activity may reduce BMI and body fat. In contrast physical inactivity may lead to an increase of BMI and body fat and may rise with increasing age. Physical activity encourages additionally a robust skeleton. Furthermore external skeletal robustness is associated with BMI in order that BMI as a measure of overweight should be consider critically. The international 10-year comparison has shown an increase of BMI in Russian children and German boys. Currently, Russian children exhibit a higher external skeletal robustness than the Germans. However, in Russian boys skeleton is less robust than ten years ago. This trend should be observed in the future as well in other countries. All in all, several measures should be used to describe health situation in children and adults. Furthermore, in children it is essential to support physical activity in order to reduce the risk of obesity and to maintain a robust skeleton. In this way diseases are able to prevent in adulthood.}, language = {en} } @phdthesis{Brothers2013, author = {Brothers, Soren M.}, title = {Carbon gains, losses, and feedbacks in shallow, eutrophic lakes of phytoplankton and macrophyte dominance}, url = {http://nbn-resolving.de/urn:nbn:de:kobv:517-opus-68200}, school = {Universit{\"a}t Potsdam}, year = {2013}, abstract = {Lakes are increasingly being recognized as an important component of the global carbon cycle, yet anthropogenic activities that alter their community structure may change the way they transport and process carbon. This research focuses on the relationship between carbon cycling and community structure of primary producers in small, shallow lakes, which are the most abundant lake type in the world, and furthermore subject to intense terrestrial-aquatic coupling due to their high perimeter:area ratio. Shifts between macrophyte and phytoplankton dominance are widespread and common in shallow lakes, with potentially large consequences to regional carbon cycling. I thus compared a lake with clear-water conditions and a submerged macrophyte community to a turbid, phytoplankton-dominated lake, describing differences in the availability, processing, and export of organic and inorganic carbon. I furthermore examined the effects of increasing terrestrial carbon inputs on internal carbon cycling processes. Pelagic diel (24-hour) oxygen curves and independent fluorometric approaches of individual primary producers together indicated that the presence of a submerged macrophyte community facilitated higher annual rates of gross primary production than could be supported in a phytoplankton-dominated lake at similar nutrient concentrations. A simple model constructed from the empirical data suggested that this difference between regime types could be common in moderately eutrophic lakes with mean depths under three to four meters, where benthic primary production is a potentially major contributor to the whole-lake primary production. It thus appears likely that a regime shift from macrophyte to phytoplankton dominance in shallow lakes would typically decrease the quantity of autochthonous organic carbon available to lake food webs. Sediment core analyses indicated that a regime shift from macrophyte to phytoplankton dominance was associated with a four-fold increase in carbon burial rates, signalling a major change in lake carbon cycling dynamics. Carbon mass balances suggested that increasing carbon burial rates were not due to an increase in primary production or allochthonous loading, but instead were due to a higher carbon burial efficiency (carbon burial / carbon deposition). This, in turn, was associated with diminished benthic mineralization rates and an increase in calcite precipitation, together resulting in lower surface carbon dioxide emissions. Finally, a period of unusually high precipitation led to rising water levels, resulting in a feedback loop linking increasing concentrations of dissolved organic carbon (DOC) to severely anoxic conditions in the phytoplankton-dominated system. High water levels and DOC concentrations diminished benthic primary production (via shading) and boosted pelagic respiration rates, diminishing the hypolimnetic oxygen supply. The resulting anoxia created redox conditions which led to a major release of nutrients, DOC, and iron from the sediments. This further transformed the lake metabolism, providing a prolonged summertime anoxia below a water depth of 1 m, and leading to the near-complete loss of fish and macroinvertebrates. Pelagic pH levels also decreased significantly, increasing surface carbon dioxide emissions by an order of magnitude compared to previous years. Altogether, this thesis adds an important body of knowledge to our understanding of the significance of the benthic zone to carbon cycling in shallow lakes. The contribution of the benthic zone towards whole-lake primary production was quantified, and was identified as an important but vulnerable site for primary production. Benthic mineralization rates were furthermore found to influence carbon burial and surface emission rates, and benthic primary productivity played an important role in determining hypolimnetic oxygen availability, thus controlling the internal sediment loading of nutrients and carbon. This thesis also uniquely demonstrates that the ecological community structure (i.e. stable regime) of a eutrophic, shallow lake can significantly influence carbon availability and processing. By changing carbon cycling pathways, regime shifts in shallow lakes may significantly alter the role of these ecosystems with respect to the global carbon cycle.}, language = {en} } @article{MalinovaSteupFettke2013, author = {Malinova, Irina and Steup, Martin and Fettke, J{\"o}rg}, title = {Carbon transitions from either Calvin cycle or transitory starch to heteroglycans as revealed by 14-C-labeling experiments using protoplasts from Arabidopsis}, series = {Physiologia plantarum}, volume = {149}, journal = {Physiologia plantarum}, number = {1}, publisher = {Wiley-Blackwell}, address = {Hoboken}, issn = {0031-9317}, doi = {10.1111/ppl.12033}, pages = {25 -- 44}, year = {2013}, abstract = {Plants metabolize transitory starch by precisely coordinated plastidial and cytosolic processes. The latter appear to include the action of water-soluble heteroglycans (SHG(in)) whose monosaccharide pattern is similar to that of apoplastic glycans (SHG(ex)) but, unlike SHG(ex), SHG(in) strongly interacts with glucosyl transferases. In this study, we analyzed starch metabolism using mesophyll protoplasts from wild-type plants and two knock-out mutants [deficient in the cytosolic transglucosidase, disproportionating isoenzyme 2 (DPE2) or the plastidial phosphoglucomutase (PGM1)] from Arabidopsis thaliana. Protoplasts prelabeled by photosynthetic (CO2)-C-14 fixation were transferred to an unlabeled medium and were darkened or illuminated. Carbon transitions from the Calvin cycle or from starch to both SHG(in) and SHG(ex) were analyzed. In illuminated protoplasts, starch turn-over was undetectable but darkened protoplasts continuously degraded starch. During illumination, neither the total C-14 content nor the labeling patterns of the sugar residues of SHG(in) were significantly altered but both the total amount and the labeling of the constituents of SHG(ex) increased with time. In darkened protoplasts, the C-14-content of most of the sugar residues of SHG(in) transiently and strongly increased and then declined. This effect was not observed in any SHG(ex) constituent. In darkened DPE2-deficient protoplasts, none of the SHG(in) constituents exhibited an essential transient increase in labeling. In contrast, some residues of SHG(in) from the PGM1 mutant exhibited a transient increase in label but this effect significantly differed from that of the wild type. Two conclusions are reached: first, SHG(in) and SHG(ex) exert different metabolic functions and second, SHG(in) is directly involved in starch degradation.}, language = {en} } @article{WangFritzschBernardingetal.2013, author = {Wang, Jing and Fritzsch, Claire and Bernarding, Johannes and Krause, Thomas and Mauritz, Karl-Heinz and Brunetti, Maddalena and Dohle, Christian}, title = {Cerebral activation evoked by the mirror illusion of the hand in stroke patients compared to normal subjects}, series = {Neurorehabilitation : an interdisciplinary journal}, volume = {33}, journal = {Neurorehabilitation : an interdisciplinary journal}, number = {4}, publisher = {IOS Press}, address = {Amsterdam}, issn = {1053-8135}, doi = {10.3233/NRE-130999}, pages = {593 -- 603}, year = {2013}, abstract = {BACKGROUND: Mirror therapy (MT) was found to improve motor function after stroke, but its neural mechanisms remain unclear, especially in single stroke patients. OBJECTIVES: The following imaging study was designed to compare brain activation patterns evoked by the mirror illusion in single stroke patients with normal subjects. METHODS: Fifteen normal volunteers and five stroke patients with severe arm paresis were recruited. Cerebral activations during movement mirroring by means of a video chain were recorded with functional magnetic resonance imaging (fMRI). Single-subject analysis was performed using SPM 8. RESULTS: For normal subjects, ten and thirteen subjects displayed lateralized cerebral activations evoked by the mirror illusion while moving their right and left hand respectively. The magnitude of this effect in the precuneus contralateral to the seen hand was not dependent on movement speed or subjective experience. Negative correlation of activation strength with age was found for the right hand only. The activation pattern in stroke patients is comparable to that of normal subjects and present in four out of five patients. CONCLUSIONS: In summary, the mirror illusion can elicit cerebral activation contralateral to the perceived hand in the majority of single normal subjects, but not in all of them. This is similar even in stroke patients with severe hemiparesis.}, language = {en} } @phdthesis{Glaubitz2013, author = {Glaubitz, Ulrike}, title = {Characterization of different rice (Oryza satvia L.) cultivars under high night temperatures in the vegetative stage}, address = {Potsdam}, pages = {158 S.}, year = {2013}, language = {en} } @phdthesis{Dahl2013, author = {Dahl, Jan-Ulrik}, title = {Characterization of the role of the sulfur carrier protein TusA for molybdenum cofactor biosynthesis in Escherichia coli}, address = {Potsdam}, year = {2013}, language = {en} } @phdthesis{FigueiraMartins2013, author = {Figueira Martins, N{\´a}dia Joana}, title = {Characterization of transgenic tobacco lines with altered contents of the chloroplast ATP synthase and Clp protease}, address = {Potsdam}, pages = {98 S.}, year = {2013}, language = {en} } @phdthesis{Blankenburg2013, author = {Blankenburg, Stefanie}, title = {Charakterisierung der GABAB-Rezeptor Subtypen 1 und 2 der Amerikanischen Großschabe Periplaneta americana}, url = {http://nbn-resolving.de/urn:nbn:de:kobv:517-opus-69648}, school = {Universit{\"a}t Potsdam}, year = {2013}, abstract = {Die nichtproteinogene Aminos{\"a}ure GABA (γ-Aminobutters{\"a}ure) gilt als der wichtigste inhibitorische Neurotransmitter im Zentralnervensystem von Vertebraten sowie Invertebraten und vermittelt ihre Wirkung u. a. {\"u}ber die metabotropen GABAB-Rezeptoren. Bisher sind diese Rezeptoren bei Insekten nur rudiment{\"a}r untersucht. F{\"u}r die Amerikanische Großschabe als etablierter Modellorganismus konnte pharmakologisch eine modulatorische Rolle der GABAB-Rezeptoren bei der Bildung von Prim{\"a}rspeichel nachgewiesen werden. Ziel dieser Arbeit war eine umfassende Charakterisierung der GABAB-Rezeptor-Subtypen 1 und 2 von Periplaneta americana. Unter Verwendung verschiedenster Klonierungsstrategien sowie der Kooperationsm{\"o}glichkeit mit der Arbeitsgruppe von Prof. Dr. T. Miura (Hokkaido, Japan) in Hinsicht auf eine dort etablierte P. americana EST-Datenbank gelang die Klonierung von zwei Rezeptor-cDNAs. Die Analyse der abgeleiteten Aminos{\"a}uresequenzen auf GB-spezifische Dom{\"a}nen und konservierte Aminos{\"a}ure-Reste, sowie der Vergleich zu bekannten GB Sequenzen anderer Arten legen nahe, dass es sich bei den isolierten Sequenzen um die GABAB-Rezeptor-Subtypen 1 und 2 (PeaGB1 und PeaGB2) handelt. F{\"u}r die funktionelle und pharmakologische Charakterisierung des Heteromers aus PeaGB1 und PeaGB2 wurden Expressionskonstrukte f{\"u}r die Transfektion in HEK-flpTM-Zellen hergestellt. Das Heteromer aus PeaGB1 und PeaGB2 hemmt bei steigenden GABA-Konzentrationen die cAMP-Produktion. Die Substanzen SKF97541 und 3-APPA konnten als Agonisten identifiziert werden. CGP55845 und CGP54626 wirken als vollwertige Antagonisten. Das in vitro ermittelte pharmakologische Profil im Vergleich zur Pharmakologie an der isolierten Dr{\"u}se best{\"a}tigt, dass die GABA-Wirkung in der Speicheldr{\"u}se tats{\"a}chlich von GBs vermittelt wird. F{\"u}r die immunhistochemische Charakterisierung konnte ein spezifischer polyklonaler Antik{\"o}rper gegen die extrazellul{\"a}re Schleife 2 des PeaGB1 generiert werden. Ein weiterer Antik{\"o}rper, welcher gegen den PeaGB2 gerichtet ist, erwies sich hingegen nicht als ausreichend spezifisch. Western-Blot-Analysen best{\"a}tigen das Vorkommen beider Subtypen im Zentralnervensystem von P. americana. Zudem wird der PeaGB1 in der Speicheldr{\"u}se und in den Geschlechtsdr{\"u}sen der Schabenm{\"a}nnchen exprimiert. Immunhistochemische Analysen zeigen eine PeaGB1-{\"a}hnliche Markierung in den GABAergen Fasern der Speicheldr{\"u}se auf. Demnach fungiert der PeaGB1 hier als Autorezeptor. Weiterhin konnte eine PeaGB1-{\"a}hnliche Markierung in nahezu allen Gehirnneuropilen festgestellt werden. Auch die akzessorischen Dr{\"u}sen der M{\"a}nnchen, Pilzdr{\"u}se und Phallusdr{\"u}se, sind PeaGB1-immunreaktiv.}, language = {de} } @phdthesis{Hasdorf2013, author = {Hasdorf, Sebastian}, title = {Charakterisierung der Photosynthese in an extreme Standorte angepassten Arabidopsi thaliana {\"O}kotypen und in ribosomalen Tabakmutanten}, address = {Potsdam}, pages = {139 S.}, year = {2013}, language = {de} } @article{GergsZenkerGrimmetal.2013, author = {Gergs, Andre and Zenker, Armin and Grimm, Volker and Preuss, Thomas G.}, title = {Chemical and natural stressors combined from cryptic effects to population extinction}, series = {Scientific reports}, volume = {3}, journal = {Scientific reports}, number = {2}, publisher = {Nature Publ. Group}, address = {London}, issn = {2045-2322}, doi = {10.1038/srep02036}, pages = {8}, year = {2013}, abstract = {In addition to natural stressors, populations are increasingly exposed to chemical pollutants released into the environment. We experimentally demonstrate the loss of resilience for Daphnia magna populations that are exposed to a combination of natural and chemical stressors even though effects on population size of a single stressor were cryptic, i.e. hard to detect statistically. Data on Daphnia population demography and along with model-based exploration of our predator-prey system revealed that direct trophic interactions changed the population size-structure and thereby increased population vulnerability to the toxicant which acts in a size selective manner. Moreover, population vulnerability to the toxicant increases with predator size and predation intensity whereas indirect trait-mediated interactions via predator kairomones may buffer chemical effects to a certain extent. Our study demonstrates that population size can be a poor endpoint for risk assessments of chemicals and that ignoring disturbance interactions can lead to severe underestimation of extinction risk.}, language = {en} } @article{LinklaterMayerSwaisgood2013, author = {Linklater, Wayne L. and Mayer, Katharina and Swaisgood, Ronald R.}, title = {Chemical signals of age, sex and identity in black rhinoceros}, series = {Animal behaviour}, volume = {85}, journal = {Animal behaviour}, number = {3}, publisher = {Elsevier}, address = {London}, issn = {0003-3472}, doi = {10.1016/j.anbehav.2012.12.034}, pages = {671 -- 677}, year = {2013}, abstract = {Olfactory communication may be particularly important to black rhinoceros, Diceros bicornis, because they are solitary living and have comparatively poor eyesight but their populations are structured by inter-and intrasexual relationships. Understanding olfactory functions and processes might achieve better conservation management but their study in rhinoceros remains anecdotal or descriptive. Experimental approaches are required but rarely possible as rhinoceros are difficult to observe and manipulate. We measured the olfactory investigation behaviour (duration and frequency of sniffing) of black rhinoceros in four experiments designed to determine the function of chemosignals in dung and urine. A habituationedishabituation trial demonstrated that black rhinoceros discriminated individually distinctive odours from faecal signals (experiment 1). When adults (>6 years old) were presented with dung from conspecifics of different sex and age classes (adult, and subadult from 2 to 4 years old), male dung was investigated more by both sexes, and females investigated subadult dung more (experiment 2). Both dung and urine from the same adult donors were investigated by both sexes, but male dung was investigated more than female dung and female urine more than male urine, although differences were statistically weak (experiment 3). Lastly, fresh faecal samples and those aged 1, 2, 4, 16 and 32 days were similarly investigated, indicating that they still function as olfactory signals. Together the results indicate that dung or urine signalled age, sex and identity to conspecifics and signals may persist as dung decays. Chemosignals are likely to be important to the social and spatial organization of black rhinoceros.}, language = {en} } @article{LiangHeinrichSimardetal.2013, author = {Liang, Wei and Heinrich, Ingo and Simard, Sonia and Helle, Gerhard and Linan, Isabel Dorado and Heinken, Thilo}, title = {Climate signals derived from cell anatomy of Scots pine in NE Germany}, series = {Tree physiology}, volume = {33}, journal = {Tree physiology}, number = {8}, publisher = {Oxford Univ. Press}, address = {Oxford}, issn = {0829-318X}, doi = {10.1093/treephys/tpt059}, pages = {833 -- 844}, year = {2013}, abstract = {Tree-ring chronologies of Pinus sylvestris L. from latitudinal and altitudinal limits of the species distribution have been widely used for climate reconstructions, but there are many sites within the temperate climate zone, as is the case in northeastern Germany, at which there is little evidence of a clear climate signal in the chronologies. In this study, we developed long chronologies of several cell structure variables (e. g., average lumen area and cell wall thickness) from P. sylvestris growing in northeastern Germany and investigated the influence of climate on ring widths and cell structure variables. We found significant correlations between cell structure variables and temperature, and between tree-ring width and relative humidity and vapor pressure, respectively, enabling the development of robust reconstructions from temperate sites that have not yet been realized. Moreover, it has been shown that it may not be necessary to detrend chronologies of cell structure variables and thus low-frequency climate signals may be retrieved from longer cell structure chronologies. The relatively extensive resource of archaeological material of P. sylvestris covering approximately the last millennium may now be useful for climate reconstructions in northeastern Germany and other sites in the temperate climate zone.}, language = {en} } @article{PlueDeFrenneAcharyaetal.2013, author = {Plue, Jan and De Frenne, Pieter and Acharya, Kamal P. and Brunet, Jorg and Chabrerie, Olivier and Decocq, Guillaume and Diekmann, Martin and Graae, Bente J. and Heinken, Thilo and Hermy, Martin and Kolb, Annette and Lemke, Isgard and Liira, Jaan and Naaf, Tobias and Shevtsova, Anna and Verheyen, Kris and Wulf, Monika and Cousins, Sara A. O.}, title = {Climatic control of forest herb seed banks along a latitudinal gradient}, series = {Global ecology and biogeography : a journal of macroecology}, volume = {22}, journal = {Global ecology and biogeography : a journal of macroecology}, number = {10}, publisher = {Wiley-Blackwell}, address = {Hoboken}, issn = {1466-822X}, doi = {10.1111/geb.12068}, pages = {1106 -- 1117}, year = {2013}, abstract = {Aim Seed banks are central to the regeneration strategy of many plant species. Any factor altering seed bank density thus affects plant regeneration and population dynamics. Although seed banks are dynamic entities controlled by multiple environmental drivers, climatic factors are the most comprehensive, but still poorly understood. This study investigates how climatic variation structures seed production and resulting seed bank patterns. Location Temperate forests along a 1900km latitudinal gradient in north-western (NW) Europe. Methods Seed production and seed bank density were quantified in 153 plots along the gradient for four forest herbs with different seed longevity: Geum urbanum, Milium effusum, Poa nemoralis and Stachys sylvatica. We tested the importance of climatic and local environmental factors in shaping seed production and seed bank density. Results Seed production was determined by population size, and not by climatic factors. G.urbanum and M.effusum seed bank density declined with decreasing temperature (growing degree days) and/or increasing temperature range (maximum-minimum temperature). P.nemoralis and S.sylvatica seed bank density were limited by population size and not by climatic variables. Seed bank density was also influenced by other, local environmental factors such as soil pH or light availability. Different seed bank patterns emerged due to differential seed longevities. Species with long-lived seeds maintained constant seed bank densities by counteracting the reduced chance of regular years with high seed production at colder northern latitudes. Main conclusions Seed bank patterns show clear interspecific variation in response to climate across the distribution range. Not all seed banking species may be as well equipped to buffer climate change via their seed bank, notably in short-term persistent species. Since the buffering capacity of seed banks is key to species persistence, these results provide crucial information to advance climatic change predictions on range shifts, community and biodiversity responses.}, language = {en} } @article{DormannElithBacheretal.2013, author = {Dormann, Carsten F. and Elith, Jane and Bacher, Sven and Buchmann, Carsten M. and Carl, Gudrun and Carre, Gabriel and Garcia Marquez, Jaime R. and Gruber, Bernd and Lafourcade, Bruno and Leitao, Pedro J. and M{\"u}nkem{\"u}ller, Tamara and McClean, Colin and Osborne, Patrick E. and Reineking, Bjoern and Schr{\"o}der-Esselbach, Boris and Skidmore, Andrew K. and Zurell, Damaris and Lautenbach, Sven}, title = {Collinearity a review of methods to deal with it and a simulation study evaluating their performance}, series = {Ecography : pattern and diversity in ecology ; research papers forum}, volume = {36}, journal = {Ecography : pattern and diversity in ecology ; research papers forum}, number = {1}, publisher = {Wiley-Blackwell}, address = {Hoboken}, issn = {0906-7590}, doi = {10.1111/j.1600-0587.2012.07348.x}, pages = {27 -- 46}, year = {2013}, abstract = {Collinearity refers to the non independence of predictor variables, usually in a regression-type analysis. It is a common feature of any descriptive ecological data set and can be a problem for parameter estimation because it inflates the variance of regression parameters and hence potentially leads to the wrong identification of relevant predictors in a statistical model. Collinearity is a severe problem when a model is trained on data from one region or time, and predicted to another with a different or unknown structure of collinearity. To demonstrate the reach of the problem of collinearity in ecology, we show how relationships among predictors differ between biomes, change over spatial scales and through time. Across disciplines, different approaches to addressing collinearity problems have been developed, ranging from clustering of predictors, threshold-based pre-selection, through latent variable methods, to shrinkage and regularisation. Using simulated data with five predictor-response relationships of increasing complexity and eight levels of collinearity we compared ways to address collinearity with standard multiple regression and machine-learning approaches. We assessed the performance of each approach by testing its impact on prediction to new data. In the extreme, we tested whether the methods were able to identify the true underlying relationship in a training dataset with strong collinearity by evaluating its performance on a test dataset without any collinearity. We found that methods specifically designed for collinearity, such as latent variable methods and tree based models, did not outperform the traditional GLM and threshold-based pre-selection. Our results highlight the value of GLM in combination with penalised methods (particularly ridge) and threshold-based pre-selection when omitted variables are considered in the final interpretation. However, all approaches tested yielded degraded predictions under change in collinearity structure and the folk lore'-thresholds of correlation coefficients between predictor variables of |r| >0.7 was an appropriate indicator for when collinearity begins to severely distort model estimation and subsequent prediction. The use of ecological understanding of the system in pre-analysis variable selection and the choice of the least sensitive statistical approaches reduce the problems of collinearity, but cannot ultimately solve them.}, language = {en} } @article{PfestorfWeissMuelleretal.2013, author = {Pfestorf, H. and Weiss, L. and M{\"u}ller, J. and Boch, Steffen and Socher, S. A. and Prati, Daniel and Sch{\"o}ning, Ingo and Weisser, W. and Fischer, M. and Jeltsch, Florian}, title = {Community mean traits as additional indicators to monitor effects of land-use intensity On grassland plant diversity}, series = {Perspectives in plant ecology, evolution and systematics}, volume = {15}, journal = {Perspectives in plant ecology, evolution and systematics}, number = {1}, publisher = {Elsevier}, address = {Jena}, issn = {1433-8319}, doi = {10.1016/j.ppees.2012.10.003}, pages = {1 -- 11}, year = {2013}, abstract = {Semi-natural grasslands, biodiversity hotspots in Central-Europe, suffer from the cessation of traditional land-use. Amount and intensity of these changes challenge current monitoring frameworks typically based on classic indicators such as selected target species or diversity indices. Indicators based on plant functional traits provide an interesting extension since they reflect ecological strategies at individual and ecological processes at community levels. They typically show convergent responses to gradients of land-use intensity over scales and regions, are more directly related to environmental drivers than diversity components themselves and enable detecting directional changes in whole community dynamics. However, probably due to their labor- and cost intensive assessment in the field, they have been rarely applied as indicators so far. Here we suggest overcoming these limitations by calculating indicators with plant traits derived from online accessible databases. Aiming to provide a minimal trait set to monitor effects of land-use intensification on plant diversity we investigated relationships between 12 community mean traits, 2 diversity indices and 6 predictors of land-use intensity within grassland communities of 3 different regions in Germany (part of the German 'Biodiversity Exploratory' research network). By standardization of traits and diversity measures, use of null models and linear mixed models we confirmed (i) strong links between functional community composition and plant diversity, (ii) that traits are closely related to land-use intensity, and (iii) that functional indicators are equally, or even more sensitive to land-use intensity than traditional diversity indices. The deduced trait set consisted of 5 traits, i.e., specific leaf area (SLA), leaf dry matter content (LDMC), seed release height, leaf distribution, and onset of flowering. These database derived traits enable the early detection of changes in community structure indicative for future diversity loss. As an addition to current monitoring measures they allow to better link environmental drivers to processes controlling community dynamics.}, language = {en} } @article{Scheffler2013, author = {Scheffler, Christiane}, title = {Comparative Biology and Human Life History}, series = {Auxology : Studying Human Growth and Development}, journal = {Auxology : Studying Human Growth and Development}, editor = {Hermanussen, Michael}, publisher = {Schweizerbart Science Publishers}, address = {Stuttgart}, isbn = {978-3-510-65278-5}, pages = {38 -- 41}, year = {2013}, language = {en} } @article{BeninaObataMehterovetal.2013, author = {Benina, Maria and Obata, Toshihiro and Mehterov, Nikolay and Ivanov, Ivan and Petrov, Veselin and Toneva, Valentina and Fernie, Alisdair R. and Gechev, Tsanko S.}, title = {Comparative metabolic profiling of Haberlea rhodopensis, Thellungiella halophyla, and Arabidopsis thaliana exposed to low temperature}, series = {Frontiers in plant science}, volume = {4}, journal = {Frontiers in plant science}, number = {1}, publisher = {Frontiers Research Foundation}, address = {Lausanne}, issn = {1664-462X}, doi = {10.3389/fpls.2013.00499}, pages = {11}, year = {2013}, abstract = {Haberlea rhodopensis is a resurrection species with extreme resistance to drought stress and desiccation but also with ability to withstand low temperatures and freezing stress. In order to identify biochemical strategies which contribute to Haberlea's remarkable stress tolerance, the metabolic reconfiguration of H. rhodopensis during low temperature (4 degrees C) and subsequent return to optimal temperatures (21 degrees C) was investigated and compared with that of the stress tolerant Thellungiella halophyla and the stress sensitive Arabidopsis thaliana. Metabolic analysis by GC-MS revealed intrinsic differences in the metabolite levels of the three species even at 21 degrees C. H. rhodopensis had significantly more raffinose, melibiose, trehalose, rhamnose, myo-inositol, sorbitol, galactinol, erythronate, threonate, 2-oxoglutarate, citrate, and glycerol than the other two species. A. thaliana had the highest levels of putrescine and fumarate, while T halophila had much higher levels of several amino acids, including alanine, asparagine, beta-alanine, histidine, isoleucine, phenylalanine, serine, threonine, and valine. In addition, the three species responded differently to the low temperature treatment and the subsequent recovery, especially with regard to the sugar metabolism. Chilling induced accumulation of maltose in H. rhodopensis and raffinose in A. thaliana but the raffinose levels in low temperature exposed Arabidopsis were still much lower than these in unstressed Haberlea. While all species accumulated sucrose during chilling, that accumulation was transient in H. rhodopensis and A. thaliana but sustained in T halophila after the return to optimal temperature. Thus, Haberlea's metabolome appeared primed for chilling stress but the low temperature acclimation induced additional stress-protective mechanisms. A diverse array of sugars, organic acids, and polyols constitute Haberlea's main metabolic defence mechanisms against chilling, while accumulation of amino acids and amino acid derivatives contribute to the low temperature acclimation in Arabidopsis and Thellungiella. Collectively, these results show inherent differences in the metabolomes under the ambient temperature and the strategies to respond to low temperature in the three species.}, language = {en} } @article{MassieRyabovBlasiusetal.2013, author = {Massie, Thomas Michael and Ryabov, Alexei and Blasius, Bernd and Weithoff, Guntram and Gaedke, Ursula}, title = {Complex transient dynamics of stage-structured populations in response to environmental changes}, series = {The American naturalist : a bi-monthly journal devoted to the advancement and correlation of the biological sciences}, volume = {182}, journal = {The American naturalist : a bi-monthly journal devoted to the advancement and correlation of the biological sciences}, number = {1}, publisher = {Univ. of Chicago Press}, address = {Chicago}, issn = {0003-0147}, doi = {10.1086/670590}, pages = {103 -- 119}, year = {2013}, abstract = {Stage structures of populations can have a profound influence on their dynamics. However, not much is known about the transient dynamics that follow a disturbance in such systems. Here we combined chemostat experiments with dynamical modeling to study the response of the phytoplankton species Chlorella vulgaris to press perturbations. From an initially stable steady state, we altered either the concentration or dilution rate of a growth-limiting resource. This disturbance induced a complex transient response-characterized by the possible onset of oscillations-before population numbers relaxed to a new steady state. Thus, cell numbers could initially change in the opposite direction of the long-term change. We present quantitative indexes to characterize the transients and to show that the dynamic response is dependent on the degree of synchronization among life stages, which itself depends on the state of the population before perturbation. That is, we show how identical future steady states can be approached via different transients depending on the initial population structure. Our experimental results are supported by a size-structured model that accounts for interplay between cell-cycle and population-level processes and that includes resource-dependent variability in cell size. Our results should be relevant to other populations with a stage structure including organisms of higher order.}, language = {en} }