@phdthesis{Nowak2020,
  author    = {Nowak, Jacqueline},
  title     = {Devising computational tools to quantify the actin cytoskeleton and pavement cell shape using network-based approaches},
  school      = {Universit{\"a}t Potsdam},
  pages     = {123},
  year      = {2020},
  abstract  = {Recent advances in microscopy have led to an improved visualization of different cell processes. Yet, this also leads to a higher demand of tools which can process images in an automated and quantitative fashion. Here, we present two applications that were developed to quantify different processes in eukaryotic cells which rely on the organization and dynamics of the cytoskeleton.. In plant cells, microtubules and actin filaments form the backbone of the cytoskeleton. These structures support cytoplasmic streaming, cell wall organization and tracking of cellular material to and from the plasma membrane. To better understand the underlying mechanisms of cytoskeletal organization, dynamics and coordination, frameworks for the quantification are needed. While this is fairly well established for the microtubules, the actin cytoskeleton has remained difficult to study due to its highly dynamic behaviour. One aim of this thesis was therefore to provide an automated framework to quantify and describe actin organization and dynamics. We used the framework to represent actin structures as networks and examined the transport efficiency in Arabidopsis thaliana hypocotyl cells. Furthermore, we applied the framework to determine the growth mode of cotton fibers and compared the actin organization in wild-type and mutant cells of rice. Finally, we developed a graphical user interface for easy usage. Microtubules and the actin cytoskeleton also play a major role in the morphogenesis of epidermal leaf pavement cells. These cells have highly complex and interdigitated shapes which are hard to describe in a quantitative way. While the relationship between microtubules, the actin cytoskeleton and shape formation is the object of many studies, it is still not clear how and if the cytoskeletal components predefine indentations and protrusions in pavement cell shapes. To understand the underlying cell processes which coordinate cell morphogenesis, a quantitative shape descriptor is needed. Therefore, the second aim of this thesis was the development of a network-based shape descriptor which captures global and local shape features, facilitates shape comparison and can be used to evaluate shape complexity. We demonstrated that our framework can be used to describe and compare shapes from various domains. In addition, we showed that the framework accurately detects local shape features of pavement cells and outperform contending approaches. In the third part of the thesis, we extended the shape description framework to describe pavement cell shape features on tissue-level by proposing different network representations of the underlying imaging data.},
  language  = {en}
}
@phdthesis{Paraskevopoulou2019,
  author    = {Paraskevopoulou, Sofia},
  title     = {Adaptive genetic variation and responses to thermal stress in brachionid rotifers},
  pages     = {IV, 177},
  year      = {2019},
  abstract  = {The importance of cryptic diversity in rotifers is well understood regarding its ecological consequences, but there remains an in depth comprehension of the underlying molecular mechanisms and forces driving speciation. Temperature has been found several times to affect species spatio-temporal distribution and organisms' performance, but we lack information on the mechanisms that provide thermal tolerance to rotifers. High cryptic diversity was found recently in the freshwater rotifer "Brachionus calyciflorus", showing that the complex comprises at least four species: B. calyciflorus sensu stricto (s.s.), B. fernandoi, B. dorcas, and B. elevatus. The temporal succession among species which have been observed in sympatry led to the idea that temperature might play a crucial role in species differentiation. The central aim of this study was to unravel differences in thermal tolerance between species of the former B. calyciflorus species complex by comparing phenotypic and gene expression responses. More specifically, I used the critical maximum temperature as a proxy for inter-species differences in heat-tolerance; this was modeled as a bi-dimensional phenotypic trait taking into consideration the intention and the duration of heat stress. Significant differences on heat-tolerance between species were detected, with B. calyciflorus s.s. being able to tolerate higher temperatures than B. fernandoi. Based on evidence of within species neutral genetic variation, I further examined adaptive genetic variability within two different mtDNA lineages of the heat tolerant B. calyciflorus s.s. to identify SNPs and genes under selection that might reflect their adaptive history. These analyses did not reveal adaptive genetic variation related to heat, however, they show putatively adaptive genetic variation which may reflect local adaptation. Functional enrichment of putatively positively selected genes revealed signals of adaptation in genes related to "lipid metabolism", "xenobiotics biodegradation and metabolism" and "sensory system", comprising candidate genes which can be utilized in studies on local adaptation. An absence of genetically-based differences in thermal adaptation between the two mtDNA lineages, together with our knowledge that B. calyciflorus s.s. can withstand a broad range of temperatures, led to the idea to further investigate shared transcriptomic responses to long-term exposure to high and low temperatures regimes. With this, I identified candidate genes that are involved in the response to temperature imposed stress. Lastly, I used comparative transcriptomics to examine responses to imposed heat-stress in heat-tolerant and heat-sensitive Brachionus species. I found considerably different patterns of gene expression in the two species. Most striking are patterns of expression regarding the heat shock proteins (hsps) between the two species. In the heat-tolerant, B. calyciflorus s.s., significant up-regulation of hsps at low temperatures was indicative of a stress response at the cooler end of the temperature regimes tested here. In contrast, in the heat-sensitive B. fernandoi, hsps generally exhibited up-regulation of these genes along with rising temperatures. Overall, identification of differences in expression of genes suggests suppression of protein biosynthesis to be a mechanism to increase thermal tolerance. Observed patterns in population growth are correlated with the hsp gene expression differences, indicating that this physiological stress response is indeed related to phenotypic life history performance.},
  language  = {en}
}
@phdthesis{Lehmann2018,
  author    = {Lehmann, Andreas},
  title     = {Variability in human life history traits},
  school      = {Universit{\"a}t Potsdam},
  pages     = {110},
  year      = {2018},
  language  = {de}
}
@phdthesis{Lotkowska2014,
  author    = {Lotkowska, Magda Ewa},
  title     = {Functional analysis of MYB112 transcription factor in the model plant Arabidopsis thaliana},
  url       = {http://nbn-resolving.de/urn:nbn:de:kobv:517-opus-72131},
  school      = {Universit{\"a}t Potsdam},
  year      = {2014},
  abstract  = {Transcription factors (TFs) are ubiquitous gene expression regulators and play essential roles in almost all biological processes. This Ph.D. project is primarily focused on the functional characterisation of MYB112 - a member of the R2R3-MYB TF family from the model plant Arabidopsis thaliana. This gene was selected due to its increased expression during senescence based on previous qRT-PCR expression profiling experiments of 1880 TFs in Arabidopsis leaves at three developmental stages (15 mm leaf, 30 mm leaf and 20\% yellowing leaf). MYB112 promoter GUS fusion lines were generated to further investigate the expression pattern of MYB112. Employing transgenic approaches in combination with metabolomics and transcriptomics we demonstrate that MYB112 exerts a major role in regulation of plant flavonoid metabolism. We report enhanced and impaired anthocyanin accumulation in MYB112 overexpressors and MYB112-deficient mutants, respectively. Expression profiling reveals that MYB112 acts as a positive regulator of the transcription factor PAP1 leading to increased anthocyanin biosynthesis, and as a negative regulator of MYB12 and MYB111, which both control flavonol biosynthesis. We also identify MYB112 early responsive genes using a combination of several approaches. These include gene expression profiling (Affymetrix ATH1 micro-arrays and qRT-PCR) and transactivation assays in leaf mesophyll cell protoplasts. We show that MYB112 binds to an 8-bp DNA fragment containing the core sequence (A/T/G)(A/C)CC(A/T)(A/G/T)(A/C)(T/C). By electrophoretic mobility shift assay (EMSA) and chromatin immunoprecipitation coupled to qPCR (ChIP-qPCR) we demonstrate that MYB112 binds in vitro and in vivo to MYB7 and MYB32 promoters revealing them as direct downstream target genes. MYB TFs were previously reported to play an important role in controlling flavonoid biosynthesis in plants. Many factors acting upstream of the anthocyanin biosynthesis pathway show enhanced expression levels during nitrogen limitation, or elevated sucrose content. In addition to the mentioned conditions, other environmental parameters including salinity or high light stress may trigger anthocyanin accumulation. In contrast to several other MYB TFs affecting anthocyanin biosynthesis pathway genes, MYB112 expression is not controlled by nitrogen limitation, or carbon excess, but rather is stimulated by salinity and high light stress. Thus, MYB112 constitutes a previously uncharacterised regulatory factor that modifies anthocyanin accumulation under conditions of abiotic stress.},
  language  = {en}
}
@phdthesis{Trost2014,
  author    = {Trost, Gerda},
  title     = {Poly(A) Polymerase 1 (PAPS1) influences organ size and pathogen response in Arabidopsis thaliana},
  url       = {http://nbn-resolving.de/urn:nbn:de:kobv:517-opus-72345},
  school      = {Universit{\"a}t Potsdam},
  year      = {2014},
  abstract  = {Polyadenylation of pre-mRNAs is critical for efficient nuclear export, stability, and translation of the mature mRNAs, and thus for gene expression. The bulk of pre-mRNAs are processed by canonical nuclear poly(A) polymerase (PAPS). Both vertebrate and higher-plant genomes encode more than one isoform of this enzyme, and these are coexpressed in different tissues. However, in neither case is it known whether the isoforms fulfill different functions or polyadenylate distinct subsets of pre-mRNAs. This thesis shows that the three canonical nuclear PAPS isoforms in Arabidopsis are functionally specialized owing to their evolutionarily divergent C-terminal domains. A moderate loss-of-function mutant in PAPS1 leads to increase in floral organ size, whereas leaf size is reduced. A strong loss-of-function mutation causes a male gametophytic defect, whereas a weak allele leads to reduced leaf growth. By contrast, plants lacking both PAPS2 and PAPS4 function are viable with wild-type leaf growth. Polyadenylation of SMALL AUXIN UP RNA (SAUR) mRNAs depends specifically on PAPS1 function. The resulting reduction in SAUR activity in paps1 mutants contributes to their reduced leaf growth, providing a causal link between polyadenylation of specific pre-mRNAs by a particular PAPS isoform and plant growth. Additionally, opposite effects of PAPS1 on leaf and flower growth reflect the different identities of these organs. The overgrowth of paps1 mutant petals is due to increased recruitment of founder cells into early organ primordia whereas the reduced leaf size is due to an ectopic pathogen response. This constitutive immune response leads to increased resistance to the biotrophic oomycete Hyaloperonospora arabidopsidis and reflects activation of the salicylic acid-independent signalling pathway downstream of ENHANCED DISEASE SUSCEPTIBILITY1 (EDS1)/PHYTOALEXIN DEFICIENT4 (PAD4). Immune responses are accompanied by intracellular redox changes. Consistent with this, the redox-status of the chloroplast is altered in paps1-1 mutants. The molecular effects of the paps1-1 mutation were analysed using an RNA sequencing approach that distinguishes between long- and short tailed mRNA. The results shown here suggest the existence of an additional layer of regulation in plants and possibly vertebrate gene expression, whereby the relative activities of canonical nuclear PAPS isoforms control de novo synthesized poly(A) tail length and hence expression of specific subsets of mRNAs.},
  language  = {en}
}
@phdthesis{Arnold2014,
  author    = {Arnold, Anne},
  title     = {Modeling photosynthesis and related metabolic processes : from detailed examination to consideration of the metabolic context},
  url       = {http://nbn-resolving.de/urn:nbn:de:kobv:517-opus-72277},
  school      = {Universit{\"a}t Potsdam},
  year      = {2014},
  abstract  = {Mathematical modeling of biological systems is a powerful tool to systematically investigate the functions of biological processes and their relationship with the environment. To obtain accurate and biologically interpretable predictions, a modeling framework has to be devised whose assumptions best approximate the examined scenario and which copes with the trade-off of complexity of the underlying mathematical description: with attention to detail or high coverage. Correspondingly, the system can be examined in detail on a smaller scale or in a simplified manner on a larger scale. In this thesis, the role of photosynthesis and its related biochemical processes in the context of plant metabolism was dissected by employing modeling approaches ranging from kinetic to stoichiometric models. The Calvin-Benson cycle, as primary pathway of carbon fixation in C3 plants, is the initial step for producing starch and sucrose, necessary for plant growth. Based on an integrative analysis for model ranking applied on the largest compendium of (kinetic) models for the Calvin-Benson cycle, those suitable for development of metabolic engineering strategies were identified. Driven by the question why starch rather than sucrose is the predominant transitory carbon storage in higher plants, the metabolic costs for their synthesis were examined. The incorporation of the maintenance costs for the involved enzymes provided a model-based support for the preference of starch as transitory carbon storage, by only exploiting the stoichiometry of synthesis pathways. Many photosynthetic organisms have to cope with processes which compete with carbon fixation, such as photorespiration whose impact on plant metabolism is still controversial. A systematic model-oriented review provided a detailed assessment for the role of this pathway in inhibiting the rate of carbon fixation, bridging carbon and nitrogen metabolism, shaping the C1 metabolism, and influencing redox signal transduction. The demand of understanding photosynthesis in its metabolic context calls for the examination of the related processes of the primary carbon metabolism. To this end, the Arabidopsis core model was assembled via a bottom-up approach. This large-scale model can be used to simulate photoautotrophic biomass production, as an indicator for plant growth, under so-called optimal, carbon-limiting and nitrogen-limiting growth conditions. Finally, the introduced model was employed to investigate the effects of the environment, in particular, nitrogen, carbon and energy sources, on the metabolic behavior. This resulted in a purely stoichiometry-based explanation for the experimental evidence for preferred simultaneous acquisition of nitrogen in both forms, as nitrate and ammonium, for optimal growth in various plant species. The findings presented in this thesis provide new insights into plant system's behavior, further support existing opinions for which mounting experimental evidences arise, and posit novel hypotheses for further directed large-scale experiments.},
  language  = {en}
}
@phdthesis{Serrano2014,
  author    = {Serrano, Paloma},
  title     = {Methanogens from Siberian permafrost as models for life on Mars : response to simulated martian conditions and biosignature characterization},
  url       = {http://nbn-resolving.de/urn:nbn:de:kobv:517-opus-72299},
  school      = {Universit{\"a}t Potsdam},
  year      = {2014},
  abstract  = {Mars is one of the best candidates among planetary bodies for supporting life. The presence of water in the form of ice and atmospheric vapour together with the availability of biogenic elements and energy are indicators of the possibility of hosting life as we know it. The occurrence of permanently frozen ground - permafrost, is a common phenomenon on Mars and it shows multiple morphological analogies with terrestrial permafrost. Despite the extreme inhospitable conditions, highly diverse microbial communities inhabit terrestrial permafrost in large numbers. Among these are methanogenic archaea, which are anaerobic chemotrophic microorganisms that meet many of the metabolic and physiological requirements for survival on the martian subsurface. Moreover, methanogens from Siberian permafrost are extremely resistant against different types of physiological stresses as well as simulated martian thermo-physical and subsurface conditions, making them promising model organisms for potential life on Mars. The main aims of this investigation are to assess the survival of methanogenic archaea under Mars conditions, focusing on methanogens from Siberian permafrost, and to characterize their biosignatures by means of Raman spectroscopy, a powerful technology for microbial identification that will be used in the ExoMars mission. For this purpose, methanogens from Siberian permafrost and non-permafrost habitats were subjected to simulated martian desiccation by exposure to an ultra-low subfreezing temperature (-80ºC) and to Mars regolith (S-MRS and P-MRS) and atmospheric analogues. They were also exposed to different concentrations of perchlorate, a strong oxidant found in martian soils. Moreover, the biosignatures of methanogens were characterized at the single-cell level using confocal Raman microspectroscopy (CRM). The results showed survival and methane production in all methanogenic strains under simulated martian desiccation. After exposure to subfreezing temperatures, Siberian permafrost strains had a faster metabolic recovery, whereas the membranes of non-permafrost methanogens remained intact to a greater extent. The strain Methanosarcina soligelidi SMA-21 from Siberian permafrost showed significantly higher methane production rates than all other strains after the exposure to martian soil and atmospheric analogues, and all strains survived the presence of perchlorate at the concentration on Mars. Furthermore, CRM analyses revealed remarkable differences in the overall chemical composition of permafrost and non-permafrost strains of methanogens, regardless of their phylogenetic relationship. The convergence of the chemical composition in non-sister permafrost strains may be the consequence of adaptations to the environment, and could explain their greater resistance compared to the non-permafrost strains. As part of this study, Raman spectroscopy was evaluated as an analytical technique for remote detection of methanogens embedded in a mineral matrix. This thesis contributes to the understanding of the survival limits of methanogenic archaea under simulated martian conditions to further assess the hypothetical existence of life similar to methanogens on the martian subsurface. In addition, the overall chemical composition of methanogens was characterized for the first time by means of confocal Raman microspectroscopy, with potential implications for astrobiological research.},
  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}
}
@phdthesis{Tenenboim2014,
  author    = {Tenenboim, Yehezkel},
  title     = {Characterization of a Chlamydomonas protein involved in cell division and autophagy},
  url       = {http://nbn-resolving.de/urn:nbn:de:kobv:517-opus-70650},
  school      = {Universit{\"a}t Potsdam},
  year      = {2014},
  abstract  = {The contractile vacuole (CV) is an osmoregulatory organelle found exclusively in algae and protists. In addition to expelling excessive water out of the cell, it also expels ions and other metabolites and thereby contributes to the cell's metabolic homeostasis. The interest in the CV reaches beyond its immediate cellular roles. The CV's function is tightly related to basic cellular processes such as membrane dynamics and vesicle budding and fusion; several physiological processes in animals, such as synaptic neurotransmission and blood filtration in the kidney, are related to the CV's function; and several pathogens, such as the causative agents of sleeping sickness, possess CVs, which may serve as pharmacological targets. The green alga Chlamydomonas reinhardtii has two CVs. They are the smallest known CVs in nature, and they remain relatively untouched in the CV-related literature. Many genes that have been shown to be related to the CV in other organisms have close homologues in C. reinhardtii. We attempted to silence some of these genes and observe the effect on the CV. One of our genes, VMP1, caused striking, severe phenotypes when silenced. Cells exhibited defective cytokinesis and aberrant morphologies. The CV, incidentally, remained unscathed. In addition, mutant cells showed some evidence of disrupted autophagy. Several important regulators of the cell cycle as well as autophagy were found to be underexpressed in the mutant. Lipidomic analysis revealed many meaningful changes between wild-type and mutant cells, reinforcing the compromised-autophagy observation. VMP1 is a singular protein, with homologues in numerous eukaryotic organisms (aside from fungi), but usually with no relatives in each particular genome. Since its first characterization in 2002 it has been associated with several cellular processes and functions, namely autophagy, programmed cell-death, secretion, cell adhesion, and organelle biogenesis. It has been implicated in several human diseases: pancreatitis, diabetes, and several types of cancer. Our results reiterate some of the observations in VMP1's six reported homologues, but, importantly, show for the first time an involvement of this protein in cell division. The mechanisms underlying this involvement in Chlamydomonas, as well as other key aspects, such as VMP1's subcellular localization and interaction partners, still await elucidation.},
  language  = {en}
}
@phdthesis{Dethloff2013,
  author    = {Dethloff, Frederik},
  title     = {In vivo 13C stable isotope tracing of single leaf development in the cold},
  url       = {http://nbn-resolving.de/urn:nbn:de:kobv:517-opus-70486},
  school      = {Universit{\"a}t Potsdam},
  year      = {2013},
  abstract  = {Measuring the metabolite profile of plants can be a strong phenotyping tool, but the changes of metabolite pool sizes are often difficult to interpret, not least because metabolite pool sizes may stay constant while carbon flows are altered and vice versa. Hence, measuring the carbon allocation of metabolites enables a better understanding of the metabolic phenotype. The main challenge of such measurements is the in vivo integration of a stable or radioactive label into a plant without perturbation of the system. To follow the carbon flow of a precursor metabolite, a method is developed in this work that is based on metabolite profiling of primary metabolites measured with a mass spectrometer preceded by a gas chromatograph (Wagner et al. 2003; Erban et al. 2007; Dethloff et al. submitted). This method generates stable isotope profiling data, besides conventional metabolite profiling data. In order to allow the feeding of a 13C sucrose solution into the plant, a petiole and a hypocotyl feeding assay are developed. To enable the processing of large numbers of single leaf samples, their preparation and extraction are simplified and optimised. The metabolite profiles of primary metabolites are measured, and a simple relative calculation is done to gain information on carbon allocation from 13C sucrose. This method is tested examining single leaves of one rosette in different developmental stages, both metabolically and regarding carbon allocation from 13C sucrose. It is revealed that some metabolite pool sizes and 13C pools are tightly associated to relative leaf growth, i.e. to the developmental stage of the leaf. Fumaric acid turns out to be the most interesting candidate for further studies because pool size and 13C pool diverge considerably. In addition, the analyses are also performed on plants grown in the cold, and the initial results show a different metabolite pool size pattern across single leaves of one Arabidopsis rosette, compared to the plants grown under normal temperatures. Lastly, in situ expression of REIL genes in the cold is examined using promotor-GUS plants. Initial results suggest that single leaf metabolite profiles of reil2 differ from those of the WT.},
  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}
}
@phdthesis{Fleischmann2012,
  author    = {Fleischmann, Tobias},
  title     = {Deletion plastid{\"a}rer ribosomaler Proteine in Nicotiana tabacum im Kontext reduktiver Genomevolutionund Entwicklung einer Hochdurchsatzplattform zur Analysevon miRNAs in Chlamydomonas reinhardtii},
  url       = {http://nbn-resolving.de/urn:nbn:de:kobv:517-opus-60393},
  school      = {Universit{\"a}t Potsdam},
  year      = {2012},
  abstract  = {Im Rahmen des ersten Teils der vorliegenden Doktorarbeit konnten zwei nicht-essentielle (rps15, rpl36) und f{\"u}nf essentielle (rps3, rps16, rpl22, rpl23, rpl32) im Plastom von Nicotiana tabacum kodierte Proteine des plastid{\"a}ren Ribosoms bez{\"u}glich ihrer Essentialit{\"a}t charakterisiert werden. Diese Gene wurden durch gezielte Knockout-Experimente inaktiviert und die resultierenden Effekte untersucht. Die Ergebnisse lassen einen R{\"u}ckschluss auf die Lokalisation der Gene der insgesamt sieben untersuchten ribosomalen Proteine zu, die im Plastom mehrerer parasitischer, Plastiden-besitzender Spezies nicht mehr nachweisbar sind. Im Fall von rps15 k{\"o}nnte tats{\"a}chlich ein Verlust des Genes stattgefunden haben, im Fall der restlichen Gene ist eher mit einem Transfer in den Nukleus zu rechnen (rpl36 ausgenommen). Dies w{\"u}rde bedeuten, dass die Geschwindigkeit der erfolgreichen Etablierung eines Gentransfers in vielen parasitischen Spezies gegen{\"u}ber gr{\"u}nen Pflanzen stark erh{\"o}ht ist. Alle in E. coli nicht-essentiellen Proteine mit Homologen in Plastiden (rps15, rpl33, rpl36) sind auch dort, trotz ~1,5 Milliarden Jahren getrennter Evolution, nicht essentiell. Dieses Ergebnis best{\"a}tigt den schon fr{\"u}her festgestellten hohen Konservierungsgrad der bakteriellen und plastid{\"a}ren Translationsmaschinerien. Die Ph{\"a}notypen der KO-Pflanzen der nicht-essentiellen Gene (rps15, rpl36) weisen auf eine interessante Rolle von S15 w{\"a}hrend der Ribosomenassemblierung hin und im Fall von L36 auf eine wichtige funktionelle Rolle im Plastiden-Ribosomen sowie auf eine Involvierung der Plastidentranslation in der Generierung eines retrograden Signals, welches die Blattform zu beeinflussen im Stande ist. Des Weiteren konnte eine Verbindung der Translationsaktivit{\"a}t mit der Ausbildung von Seitentrieben hergestellt werden, die vermutlich auf ver{\"a}nderte Auxinsynthese im Chloroplast zur{\"u}ckzuf{\"u}hren ist. Aus dem Folgeprojekt, bei dem Doppel-KO-Pflanzen nicht-essentieller ribosomaler Proteine erzeugt wurden, l{\"a}sst sich auf eine relativ große Plastizit{\"a}t der Architektur von Plastidenribosomen schließen. Im zweiten Teil der Arbeit konnte erfolgreich ein Hochdurchsatz-Screeningsystem zur semiquantitativen Analyse von 192 verschiedenen miRNAs aus Chlamydomonas reinhardtii etabliert werden. Es gelang durch die Untersuchung von 23 verschiedenen Wachstums- und Stressbedingungen sowie Entwicklungsstadien mehrere miRNAs zu identifizieren, die eine differenzielle Expression zeigen sowie unter allen untersuchten Bedingungen konstant bleibende miRNAs nachzuweisen. Dadurch konnten mehrere vielversprechende Kandidaten-miRNAs ausgemacht werden, die nun eingehender untersucht werden k{\"o}nnen.},
  language  = {de}
}
@misc{PlathHermannSchroederetal.2010,
  author    = {Plath, Martin and Hermann, Bernd and Schr{\"o}der, Christine and Riesch, R{\"u}diger and Tobler, Michael and Garc{\´i}a de Le{\´o}n, Francisco J. and Schlupp, Ingo and Tiedemann, Ralph},
  title     = {Locally adapted fish populations maintain small-scale genetic differentiation despite perturbation by a catastrophic flood event},
  url       = {http://nbn-resolving.de/urn:nbn:de:kobv:517-opus-48599},
  year      = {2010},
  abstract  = {Background: Local adaptation to divergent environmental conditions can promote population genetic differentiation even in the absence of geographic barriers and hence, lead to speciation. Perturbations by catastrophic events, however, can distort such parapatric ecological speciation processes. Here, we asked whether an exceptionally strong flood led to homogenization of gene pools among locally adapted populations of the Atlantic molly (Poecilia mexicana, Poeciliidae) in the Cueva del Azufre system in southern Mexico, where two strong environmental selection factors (darkness within caves and/or presence of toxic H2S in sulfidic springs) drive the diversification of P. mexicana. Nine nuclear microsatellites as well as heritable female life history traits (both as a proxy for quantitative genetics and for trait divergence) were used as markers to compare genetic differentiation, genetic diversity, and especially population mixing (immigration and emigration) before and after the flood. Results: Habitat type (i.e., non-sulfidic surface, sulfidic surface, or sulfidic cave), but not geographic distance was the major predictor of genetic differentiation. Before and after the flood, each habitat type harbored a genetically distinct population. Only a weak signal of individual dislocation among ecologically divergent habitat types was uncovered (with the exception of slightly increased dislocation from the Cueva del Azufre into the sulfidic creek, El Azufre). By contrast, several lines of evidence are indicative of increased flood-induced dislocation within the same habitat type, e.g., between different cave chambers of the Cueva del Azufre. Conclusions: The virtual absence of individual dislocation among ecologically different habitat types indicates strong natural selection against migrants. Thus, our current study exemplifies that ecological speciation in this and other systems, in which extreme environmental factors drive speciation, may be little affected by temporary perturbations, as adaptations to physico-chemical stressors may directly affect the survival probability in divergent habitat types.},
  language  = {en}
}
@misc{WinklerHeinken2007,
  author    = {Winkler, Eckart and Heinken, Thilo},
  title     = {Spread of an ant-dispersed annual herb : an individual-based simulation study on population development of Melampyrum pratense L.},
  url       = {http://nbn-resolving.de/urn:nbn:de:kobv:517-opus-46491},
  year      = {2007},
  abstract  = {The paper presents a simulation and parameter-estimation approach for evaluating stochastic patterns of population growth and spread of an annual forest herb, Melampyrum pratense (Orobanchaceae). The survival of a species during large-scale changes in land use and climate will depend, to a considerable extent, on its dispersal and colonisation abilities. Predictions on species migration need a combination of field studies and modelling efforts. Our study on the ability of M. pratense to disperse into so far unoccupied areas was based on experiments in secondary woodland in NE Germany. Experiments started in 1997 at three sites where the species was not yet present, with 300 seeds sown within one square meter. Population development was then recorded until 2001 by mapping of individuals with a resolution of 5 cm. Additional observations considered density dependence of seed production. We designed a spatially explicit individual-based computer simulation model to explain the spatial patterns of population development and to predict future population spread. Besides primary drop of seeds (barochory) it assumed secondary seed transport by ants (myrmecochory) with an exponentially decreasing dispersal tail. An important feature of populationpattern explanation was the simultaneous estimation of both population-growth and dispersal parameters from consistent spatio-temporal data sets. As the simulation model produced stochastic time series and random spatially discrete distributions of individuals we estimated parameters by minimising the expectation of weighted sums of squares. These sums-ofsquares criteria considered population sizes, radial population distributions around the area of origin and distributions of individuals within squares of 25*25 cm, the range of density action. Optimal parameter values, together with the precision of the estimates, were obtained from calculating sums of squares in regular grids of parameter values. Our modelling results showed that transport of fractions of seeds by ants over distances of 1…2 m was indispensable for explaining the observed population spread that led to distances of at most 8 m from population origin within 3 years. Projections of population development over 4 additional years gave a diffusion-like increase of population area without any "outposts". This prediction generated by the simulation model gave a hypothesis which should be revised by additional field observations. Some structural deviations between observations and model output already indicated that for full understanding of population spread the set of dispersal mechanisms assumed in the model may have to be extended by additional features of plant-animal mutualism.},
  language  = {en}
}
@misc{HeinkenSchmidtvonOheimbetal.2006,
  author    = {Heinken, Thilo and Schmidt, Marcus and von Oheimb, Goddert and Kriebitzsch, Wolf-Ulrich and Ellenberg, Hermann},
  title     = {Soil seed banks near rubbing trees indicate dispersal of plant species into forests by wild boar},
  url       = {http://nbn-resolving.de/urn:nbn:de:kobv:517-opus-46476},
  year      = {2006},
  abstract  = {Current knowledge about processes that generate long-distance dispersal of plants is still limited despite its importance for persistence of populations and colonization of new potential habitats. Today wild large mammals are presumed to be important vectors for long-distance transport of diaspores within and between European temperate forest patches, and in particular wild boars recently came into focus. Here we use a specific habit of wild boar, i.e. wallowing in mud and subsequent rubbing against trees, to evaluate epizoic dispersal of vascular plant diaspores. We present soil seed bank data from 27 rubbing trees versus 27 control trees from seven forest areas in Germany. The mean number of viable seeds and the plant species number were higher in soil samples near rubbing trees compared with control trees. Ten of the 20 most frequent species were more frequent, and many species exclusively appeared in the soil samples near rubbing trees. The large number of plant species and seeds - approximated > 1000 per tree - in the soils near rubbing trees is difficult to explain unless the majority were dispersed by wild boar. Hooked and bristly diaspores, i.e. those adapted to epizoochory, were more frequent, above that many species with unspecialised diaspores occurred exclusively near rubbing trees. Different to plant species closely tied to forest species which occur both in forest and open vegetation, and non-forest species were more frequent near rubbing trees compared with controls. These findings are consistent with previous studies on diaspore loads in the coats and hooves of shot wild boars. However, our method allows to identify the transport of diaspores from the open landscape into forest stands where they might especially emerge after disturbance, and a clustered distribution of epizoochorically dispersed seeds. Moreover, accumulation of seeds of wetness indicators near rubbing trees demonstrates directed dispersal of plant species inhabiting wet places between remote wallows.},
  language  = {en}
}
@misc{DortayMuellerRoeber2010,
  author    = {Dortay, Hakan and M{\"u}ller-R{\"o}ber, Bernd},
  title     = {A highly efficient pipeline for protein expression in Leishmania tarentolae sing infrared fluorescence protein as marker},
  url       = {http://nbn-resolving.de/urn:nbn:de:kobv:517-opus-44773},
  year      = {2010},
  abstract  = {Background: Leishmania tarentolae, a unicellular eukaryotic protozoan, has been established as a novel host for recombinant protein production in recent years. Current protocols for protein expression in Leishmania are, however, time consuming and require extensive lab work in order to identify well-expressing cell lines. Here we established an alternative protein expression work-flow that employs recently engineered infrared fluorescence protein (IFP) as a suitable and easy-to-handle reporter protein for recombinant protein expression in Leishmania. As model proteins we tested three proteins from the plant Arabidopsis thaliana, including a NAC and a type-B ARR transcription factor. Results: IFP and IFP fusion proteins were expressed in Leishmania and rapidly detected in cells by deconvolution microscopy and in culture by infrared imaging of 96-well microtiter plates using small cell culture volumes (2 μL - 100 μL). Motility, shape and growth of Leishmania cells were not impaired by intracellular accumulation of IFP. In-cell detection of IFP and IFP fusion proteins was straightforward already at the beginning of the expression pipeline and thus allowed early pre-selection of well-expressing Leishmania clones. Furthermore, IFP fusion proteins retained infrared fluorescence after electrophoresis in denaturing SDS-polyacrylamide gels, allowing direct in-gel detection without the need to disassemble cast protein gels. Thus, parameters for scaling up protein production and streamlining purification routes can be easily optimized when employing IFP as reporter. Conclusions: Using IFP as biosensor we devised a protocol for rapid and convenient protein expression in Leishmania tarentolae. Our expression pipeline is superior to previously established methods in that it significantly reduces the hands-on-time and work load required for identifying well-expressing clones, refining protein production parameters and establishing purification protocols. The facile in-cell and in-gel detection tools built on IFP make Leishmania amenable for high-throughput expression of proteins from plant and animal sources.},
  language  = {en}
}
@phdthesis{Leicht2008,
  author    = {Leicht, Katja},
  title     = {Positionelle Klonierung von Tbc1d1 als Kandidatengen f{\"u}r Adipositas},
  url       = {http://nbn-resolving.de/urn:nbn:de:kobv:517-opus-34610},
  school      = {Universit{\"a}t Potsdam},
  year      = {2008},
  abstract  = {Nob1 (New Zealand obese 1) bezeichnet einen Adipositas-QTL auf Chr. 5 der Maus (LODBMI >3,3), der in einem R{\"u}ckkreuzungsexperiment der Mausst{\"a}mme NZO (adip{\"o}s) und SJL (schlank) identifiziert wurde. Um Kandidatengene f{\"u}r Adipositas zu finden, wurden mehr als 300 Nob1-Transkripte mit Hilfe von Genexpressionsanalysen auf Unterschiede in stoffwechselrelevanten Geweben zwischen beiden Mausst{\"a}mmen untersucht. Sieben Gene zeigten eine differentielle Expression: 2310045A20Rik, Tbc1d1, Ppp1cb, Mll5, Insig1, Abhd1 und Alox5ap. Die codierenden Bereiche dieser Gene wurden anschließend auf Sequenzunterschiede zwischen NZO und SJL untersucht. Nur im Gen Tbc1d1, das im Peak-Bereich des Nob1 lokalisiert ist, wurde eine SJL-spezifische Deletion von sieben Basen detektiert, die zu einer Leserasterverschiebung und einem vorzeitigen Abbruch des Proteins in der funktionellen Rab-GAP-Dom{\"a}ne f{\"u}hrt (Loss-of-Function-Mutation). Interessanterweise wurde eine Variante von TBC1D1 (R125W) in Kopplungsanalysen mit Adipositas beim Menschen assoziiert (Stone et al., 2006). TBC1D1 zeigt eine hohe Homologie zu TBC1D4 (AS160), das im Insulinsignalweg eine wichtige Rolle spielt. In 17 weiteren Genen im Peak-Bereich des Nob1 wurde keine weitere SJL-spezifischen Mutation detektiert. Bei NZO-Tieren erfolgte die Tbc1d1-mRNA-Expression vorwiegend in glycolytischen Fasern des Skelettmuskels. Zudem wurden zwei gewebsspezifisch exprimierte Tbc1d1-Isoformen identifiziert, die sich durch alternatives Splicen der Exone 12 und 13 unterscheiden. Die im Rahmen dieser Arbeit gefundenen Ergebnisse machen Tbc1d1 zu einem plausiblen Kandidatengen f{\"u}r den Nob1-QTL. Welche Funktion Tbc1d1 im Glucose- und Fettstoffwechsel des Skelettmuskels hat, muss in weiteren Analysen untersucht werden.},
  language  = {de}
}
@misc{Koechy2008,
  author    = {K{\"o}chy, Martin},
  title     = {Effects of simulated daily precipitation patterns on annual plant populations depend on life stage and climatic region},
  url       = {http://nbn-resolving.de/urn:nbn:de:kobv:517-opus-33747},
  year      = {2008},
  abstract  = {Background: To improve the understanding of consequences of climate change for annual plant communities, I used a detailed, grid-based model that simulates the effect of daily rainfall variability on individual plants in five climatic regions on a gradient from 100 to 800 mm mean annual precipitation (MAP). The model explicitly considers moisture storage in the soil. I manipulated daily rainfall variability by changing the daily mean rain (DMR, rain volume on rainy days averaged across years for each day of the year) by ± 20\%. At the same time I adjusted intervals appropriately between rainy days for keeping the mean annual volume constant. In factorial combination with changing DMR I also changed MAP by ± 20\%. Results: Increasing MAP generally increased water availability, establishment, and peak shoot biomass. Increasing DMR increased the time that water was continuously available to plants in the upper 15 to 30 cm of the soil (longest wet period, LWP). The effect of DMR diminished with increasing humidity of the climate. An interaction between water availability and density-dependent germination increased the establishment of seedlings in the arid region, but in the more humid regions the establishment of seedlings decreased with increasing DMR. As plants matured, competition among individuals and their productivity increased, but the size of these effects decreased with the humidity of the regions. Therefore, peak shoot biomass generally increased with increasing DMR but the effect size diminished from the semiarid to the mesic Mediterranean region. Increasing DMR reduced via LWP the annual variability of biomass in the semiarid and dry Mediterranean regions. Conclusion: More rainstorms (greater DMR) increased the recharge of soil water reservoirs in more arid sites with consequences for germination, establishment, productivity, and population persistence. The order of magnitudes of DMR and MAP overlapped partially so that their combined effect is important for projections of climate change effects on annual vegetation.},
  language  = {en}
}
@phdthesis{Riewe2008,
  author    = {Riewe, David},
  title     = {The relevance of adenylate levels and adenylate converting enzymes on metabolism and development of potato (Solanum tuberosum L.) tubers},
  url       = {http://nbn-resolving.de/urn:nbn:de:kobv:517-opus-27323},
  school      = {Universit{\"a}t Potsdam},
  year      = {2008},
  abstract  = {Adenylates are metabolites with essential function in metabolism and signaling in all living organisms. As Cofactors, they enable thermodynamically unfavorable reactions to be catalyzed enzymatically within cells. Outside the cell, adenylates are involved in signalling processes in animals and emerging evidence suggests similar signaling mechanisms in the plants' apoplast. Presumably, apoplastic apyrases are involved in this signaling by hydrolyzing the signal mediating molecules ATP and ADP to AMP. This PhD thesis focused on the role of adenylates on metabolism and development of potato (Solanum tuberosum) by using reverse genetics and biochemical approaches. To study the short and long term effect of cellular ATP and the adenylate energy charge on potato tuber metabolism, an apyrase from Escherichia coli targeted into the amyloplast was expressed inducibly and constitutively. Both approaches led to the identification of adaptations to reduced ATP/energy charge levels on the molecular and developmental level. These comprised a reduction of metabolites and pathway fluxes that require significant amounts of ATP, like amino acid or starch synthesis, and an activation of processes that produce ATP, like respiration and an immense increase in the surface-to-volume ratio. To identify extracellular enzymes involved in adenylate conversion, green fluorescent protein and activity localization studies in potato tissue were carried out. It was found that extracellular ATP is imported into the cell by an apoplastic enzyme complement consisting of apyrase, unspecific phosphatase, adenosine nucleosidase and an adenine transport system. By changing the expression of a potato specific apyrase via transgenic approaches, it was found that this enzyme has strong impact on plant and particular tuber development in potato. Whereas metabolite levels were hardly altered, transcript profiling of tubers with reduced apyrase activity revealed a significant upregulation of genes coding for extensins, which are associated with polar growth. The results are discussed in context of adaptive responses of plants to changes in the adenylate levels and the proposed role of apyrase in apoplastic purinergic signaling and ATP salvaging. In summary, this thesis provides insight into adenylate regulated processes within and outside non-photosynthetic plant cells.},
  language  = {en}
}
@misc{KoechyMathajJeltschetal.2008,
  author    = {K{\"o}chy, Martin and Mathaj, Martin and Jeltsch, Florian and Malkinson, Dan},
  title     = {Resilience of stocking capacity to changing climate in arid to Mediterranean landscapes},
  url       = {http://nbn-resolving.de/urn:nbn:de:kobv:517-opus-18720},
  year      = {2008},
  abstract  = {Small livestock is an important resource for rural human populations in dry climates. How strongly will climate change affect the capacity of the rangeland? We used hierarchical modelling to scale quantitatively the growth of shrubs and annual plants, the main food of sheep and goats, to the landscape extent in the eastern Mediterranean region. Without grazing, productivity increased in a sigmoid way with mean annual precipitation. Grazing reduced productivity more strongly the drier the landscape. At a point just under the stocking capacity of the vegetation, productivity declined precipitously with more intense grazing due to a lack of seed production of annuals. We repeated simulations with precipitation patterns projected by two contrasting IPCC scenarios. Compared to results based on historic patterns, productivity and stocking capacity did not differ in most cases. Thus, grazing intensity remains the stronger impact on landscape productivity in this dry region even in the future.},
  language  = {en}
}
@misc{WackervonElert2002,
  author    = {Wacker, Alexander and von Elert, Eric},
  title     = {Strong influences of larval diet history on subsequent post-settlement growth in the freshwater mollusc Dreissena polymorpha},
  url       = {http://nbn-resolving.de/urn:nbn:de:kobv:517-opus-17627},
  year      = {2002},
  abstract  = {Significant seasonal variation in size at settlement has been observed in newly settled larvae of Dreissena polymorpha in Lake Constance. Diet quality, which varies temporally and spatially in freshwater habitats, has been suggested as a significant factor influencing life history and development of freshwater invertebrates. Accordingly, experiments were conducted with field-collected larvae to test the hypothesis that diet quality can determine planktonic larval growth rates, size at settlement and subsequent post-metamorphic growth rates. Larvae were fed one of two diets or starved. One diet was composed of cyanobacterial cells which are deficient in polyunsaturated fatty acids (PUFAs), and the other was a mixed diet rich in PUFAs. Freshly metamorphosed animals from the starvation treatment had a carbon content per individual 70\% lower than that of larvae fed the mixed diet. This apparent exhaustion of larval internal reserves resulted in a 50\% reduction of the postmetamorphic growth rates. Growth was also reduced in animals previously fed the cyanobacterial diet. Hence, low food quantity or low food quality during the larval stage of D. polymorpha lead to irreversible effects for postmetamorphic animals, and is related to inferior competitive abilities.},
  language  = {en}
}
@misc{WackervonElert2001,
  author    = {Wacker, Alexander and von Elert, Eric},
  title     = {Polyunsaturated fatty acids : evidence for non-substitutable biochemical resources in Daphnia galeata},
  url       = {http://nbn-resolving.de/urn:nbn:de:kobv:517-opus-17587},
  year      = {2001},
  abstract  = {The factors that determine the efficiency of energy transfer in aquatic food webs have been investigated for many decades. The plant-animal interface is the most variable and least predictable of all levels in the food web. In order to study determinants of food quality in a large lake and to test the recently proposed central importance of the long-chained eicosapentaenoic acid (EPA) at the pelagic producer-grazer interface, we tested the importance of polyunsaturated fatty acids (PUFAs) at the pelagic producerconsumer interface by correlating sestonic food parameters with somatic growth rates of a clone of Daphnia galeata. Daphnia growth rates were obtained from standardized laboratory experiments spanning one season with Daphnia feeding on natural seston from Lake Constance, a large pre-alpine lake. Somatic growth rates were fitted to sestonic parameters by using a saturation function. A moderate amount of variation was explained when the model included the elemental parameters carbon (r2 = 0.6) and nitrogen (r2 = 0.71). A tighter fit was obtained when sestonic phosphorus was incorporated (r2 = 0.86). The nonlinear regression with EPA was relatively weak (r2 = 0.77), whereas the highest degree of variance was explained by three C18-PUFAs. The best (r2 = 0.95), and only significant, correlation of Daphnia's growth was found with the C18-PUFA α-linolenic acid (α-LA; C18:3n-3). This correlation was weakest in late August when C:P values increased to 300, suggesting that mineral and PUFA-limitation of Daphnia's growth changed seasonally. Sestonic phosphorus and some PUFAs showed not only tight correlations with growth, but also with sestonic α-LA content. We computed Monte Carlo simulations to test whether the observed effects of α-LA on growth could be accounted for by EPA, phosphorus, or one of the two C18-PUFAs, stearidonic acid (C18:4n-3) and linoleic acid (C18:2n-6). With >99 \% probability, the correlation of growth with α-LA could not be explained by any of these parameters. In order to test for EPA limitation of Daphnia's growth, in parallel with experiments on pure seston, growth was determined on seston supplemented with chemostat-grown, P-limited Stephanodiscus hantzschii, which is rich in EPA. Although supplementation increased the EPA content 80-800x, no significant changes in the nonlinear regression of the growth rates with α-LA were found, indicating that growth of Daphnia on pure seston was not EPA limited. This indicates that the two fatty acids, EPA and α-LA, were not mutually substitutable biochemical resources and points to different physiological functions of these two PUFAs. These results support the PUFA-limitation hypothesis for sestonic C:P < 300 but are contrary to the hypothesis of a general importance of EPA, since no evidence for EPA limitation was found. It is suggested that the resource ratios of EPA and α-LA rather than the absolute concentrations determine which of the two resources is limiting growth.},
  language  = {en}
}
@misc{KoechyBrakenhielm2008,
  author    = {K{\"o}chy, Martin and Br{\aa}kenhielm, Sven},
  title     = {Separation of effects of moderate N deposition from natural change in ground vegetation of forests and bogs},
  url       = {http://nbn-resolving.de/urn:nbn:de:kobv:517-opus-16621},
  year      = {2008},
  abstract  = {The effect of moderate rates of nitrogen deposition on ground floor vegetation is poorly predicted by uncontrolled surveys or fertilization experiments using high rates of nitrogen (N) addition. We compared the temporal trends of ground floor vegetation in permanent plots with moderate (7-13 kg ha-1 year-1) and lower bulk N deposition (4-6 kg ha-1 year-1) in southern Sweden during 1982-1998. We examined whether trends differed between growth forms (vascular plants and bryophytes) and vegetation types (three types of coniferous forest, deciduous forest, and bog). Trends of site-standardized cover and richness varied among growth forms, vegetation types, and deposition regions. Cover in spruce forests decreased at the same rate with both moderate and low deposition. In pine forests cover decreased faster with moderate deposition and in bogs cover decreased faster with low deposition. Cover of bryophytes in spruce forests increased at the same rate with both moderate and low deposition. In pine forests cover decreased faster with moderate deposition and in bogs and deciduous forests there was a strong non-linear increase with moderate deposition. The trend of number of vascular plants was constant with moderate and decreased with low deposition. We found no trend in the number of bryophyte species. We propose that the decrease of cover and number with low deposition was related to normal ecosystem development (increased shading), suggesting that N deposition maintained or increased the competitiveness of some species in the moderate-deposition region. Deposition had no consistent negative effect on vegetation suggesting that it is less important than normal successional processes.},
  language  = {en}
}
@phdthesis{Wasiolka2007,
  author    = {Wasiolka, Bernd},
  title     = {The impact of overgrazing on reptile diversity and population dynamics of Pedioplanis l. lineoocellata in the southern Kalahari},
  url       = {http://nbn-resolving.de/urn:nbn:de:kobv:517-opus-16611},
  school      = {Universit{\"a}t Potsdam},
  year      = {2007},
  abstract  = {Die Vegetationskomposition und -struktur, beispielsweise die unterschiedliche Architektur von B{\"a}umen, Str{\"a}uchern, Gr{\"a}sern und Kr{\"a}utern, bietet ein großes Spektrum an Habitaten und Nischen, die wiederum eine hohe Tierdiversit{\"a}t in den Savannensystemen des s{\"u}dlichen Afrikas erm{\"o}glichen. Dieses {\"O}kosystem wurde jedoch {\"u}ber Jahrzehnte weltweit durch intensive anthropogene Landnutzung (z.B. Viehwirtschaft) nachhaltig ver{\"a}ndert. Dabei wurden die Zusammensetzung, Diversit{\"a}t und Struktur der Vegetation stark ver{\"a}ndert. {\"U}berweidung in Savannensystemen f{\"u}hrt zu einer Degradation des Habitates einhergehend mit dem Verlust von perennierenden Gr{\"a}sern und krautiger Vegetation. Dies f{\"u}hrt zu einem Anstieg an vegetationsfreien Bodenfl{\"a}chen. Beides, sowohl der Verlust an perennierenden Gr{\"a}sern und krautiger Vegetation sowie der Anstieg an vegetationsfreien Fl{\"a}chen f{\"u}hrt zu verbesserten Etablierungsbedingungen f{\"u}r Str{\"a}ucher (z.B. Rhigozum trichotomum, Acacia mellifera) und auf lange Sicht zu stark verbuschten Fl{\"a}chen. Die Tierdiversit{\"a}t in Savannen ist hiervon entscheidend beeinflusst. Mit sinkender struktureller Diversit{\"a}t verringert sich auch die Tierdiversit{\"a}t. W{\"a}hrend der Einfluss von {\"U}berweidung auf die Vegetation relativ gut untersucht ist sind Informationen {\"u}ber den Einfluss von {\"U}berweidung auf die Tierdiversit{\"a}t, speziell f{\"u}r Reptilien, eher sp{\"a}rlich vorhanden. Zus{\"a}tzlich ist sehr wenig bekannt zum Einfluss auf die Populationsdynamik (z.B. Verhaltensanpassungen, Raumnutzung, {\"U}berlebensrate, Sterberate) einzelner Reptilienarten. Ziel meiner Doktorarbeit ist es den Einfluss von {\"U}berweidung durch kommerzielle Farmnutzung auf die Reptiliengemeinschaft und auf verschiedene Aspekte der Populationsdynamik der Echse Pedioplanis lineoocellata lineoocellata zu untersuchen. Hinsichtlich bestimmter Naturschutzmaßnahmen ist es einerseits wichtig zu verstehen welchen Auswirkungen {\"U}berweidung auf die gesamte Reptiliengemeinschaft hat. Und zum anderen wie entscheidende Faktoren der Populationsdynamik beeinflusst werden. Beides f{\"u}hrt zu einem besseren Verst{\"a}ndnis der Reaktion von Reptilien auf Habitatdegradation zu erlangen. Die Ergebnisse meiner Doktorarbeit zeigen eindeutig einen negativen Einfluss der {\"U}berweidung und der daraus resultierende Habitatdegradation auf (1) die gesamte Reptiliengemeinschaft und (2) auf einzelne Aspekte der Populationsdynamik von P. lineoocellata. Im Teil 1 wird die signifikante Reduzierung der Reptiliendiversit{\"a}t und Abundanz in degradierten Habitaten beschrieben. Im zweiten Teil wird gezeigt, dass P. lineoocellata das Verhalten an die verschlechterten Lebensbedingungen anpassen kann. Die Art bewegt sich sowohl h{\"a}ufiger als auch {\"u}ber einen l{\"a}ngeren Zeitraum und legt dabei gr{\"o}ßere Distanzen zur{\"u}ck. Zus{\"a}tzlich vergr{\"o}ßerte die Art ihr Revier (home range) (Teil 3). Im abschließenden Teil wird der negative Einfluss von {\"U}berweidung auf die Populationsdynamik von P. lineoocellata beschrieben: In degradierten Habitaten nimmt die Populationsgr{\"o}ße von adulten und juvenilen Echsen ab, die {\"U}berlebens- und Geburtenrate sinken, w{\"a}hren zus{\"a}tzlich das Pr{\"a}dationsrisiko ansteigt. Verantwortlich hierf{\"u}r ist zum einen die ebenfalls reduzierte Nahrungsverf{\"u}gbarkeit (Arthropoden) auf degradierten Fl{\"a}chen. Dies hat zur Folge, dass die Populationsgr{\"o}ße abnimmt und die Fitness der Individuen verringert wird, welches sich durch eine Reduzierung der {\"U}berlebens- und Geburtenrate bemerkbar macht. Und zum anderen ist es die Reduzierung der Vegetationsbedeckung und der R{\"u}ckgang an perennierenden Gr{\"a}sern welche sich negativ auswirken. Als Konsequenz hiervon gehen Nischen und Mikrohabitate verloren und die M{\"o}glichkeiten der Reptilien zur Thermoregulation sind verringert. Des Weiteren hat dieser Verlust an perennierender Grasbedeckung auch ein erh{\"o}htes Pr{\"a}dationsrisikos zur Folge. Zusammenfassend l{\"a}sst sich sagen, dass nicht nur B{\"a}ume und Str{\"a}ucher, wie in anderen Studien gezeigt, eine bedeutende Rolle f{\"u}r die Diversit{\"a}t spielen, sondern auch das perennierende Gras eine wichtige Rolle f{\"u}r die Faunendiversit{\"a}t spielt. Weiterhin zeigte sich, dass Habitatdegradation nicht nur die Population als gesamtes beeinflusst, sondern auch das Verhalten und Populationsparameter einzelner Arten. Des Weiteren ist es Reptilien m{\"o}glich durch Verhaltensflexibilit{\"a}t auf verschlechterte Umweltbedingen zu reagieren.},
  language  = {en}
}
@misc{Koechy2006,
  author    = {K{\"o}chy, Martin},
  title     = {Opposite trends in life stages of annual plants caused by daily rainfall variability},
  url       = {http://nbn-resolving.de/urn:nbn:de:kobv:517-opus-14699},
  pages     = {347 -- 357},
  year      = {2006},
  abstract  = {Global Circulation Models of climate predict not only a change of annual precipitation amounts but also a shift in the daily distribution. To improve the understanding of the importance of daily rain pattern for annual plant communities, which represent a large portion of semi-natural vegetation in the Middle East, I used a detailed, spatially explicit model. The model explicitly considers water storage in the soil and has been parameterized and validated with data collected in field experiments in Israel and data from the literature. I manipulated daily rainfall variability by increasing the mean daily rain intensity on rainy days (MDI, rain volume/day) and decreasing intervals between rainy days while keeping the mean annual amount constant. In factorial combination, I also increased mean annual precipitation (MAP). I considered five climatic regions characterized by 100, 300, 450, 600, and 800 mm MAP. Increasing MDI decreased establishment when MAP was >250 mm but increased establishment at more arid sites. The negative effect of increasing MDI was compensated by increasing mortality with increasing MDI in dry and typical Mediterranean regions (c. 360-720 mm MAP). These effects were strongly tied to water availability in upper and lower soil layers and modified by competition among seedlings and adults. Increasing MAP generally increased water availability, establishment, and density. The order of magnitudes of MDI and MAP effects overlapped partially so that their combined effect is important for projections of climate change effects on annual vegetation. The effect size of MAP and MDI followed a sigmoid curve along the MAP gradient indicating that the semi-arid region (≈300 mm MAP) is the most sensitive to precipitation change with regard to annual communitie},
  subject      = {Klima{\"a}nderung},
  language  = {en}
}
@misc{Koechy2006,
  author    = {K{\"o}chy, Martin},
  title     = {Stochastic time series of daily precipitation for the interior of Israel},
  url       = {http://nbn-resolving.de/urn:nbn:de:kobv:517-opus-13155},
  year      = {2006},
  abstract  = {This contribution describes a generator of stochastic time series of daily precipitation for the interior of Israel from c. 90 to 900 mm mean annual precipitation (MAP) as a tool for studies of daily rain variability. The probability of rainfall on a given day of the year is described by a regular Gaussian peak curve function. The amount of rain is drawn randomly from an exponential distribution whose mean is the daily mean rain amount (averaged across years for each day of the year) described by a flattened Gaussian peak curve. Parameters for the curves have been calculated from monthly aggregated, long-term rain records from seven meteorological stations. Parameters for arbitrary points on the MAP gradient are calculated from a regression equation with MAP as the only independent variable. The simple structure of the generator allows it to produce time series with daily rain patterns that are projected under climate change scenarios and simultaneously control MAP. Increasing within-year variability of daily precipitation amounts also increases among-year variability of MAP as predicted by global circulation models. Thus, the time series incorporate important characteristics for climate change research and represent a flexible tool for simulations of daily vegetation or surface hydrology dynamics.},
  language  = {en}
}
@misc{KoechyTielboerger2006,
  author    = {K{\"o}chy, Martin and Tielb{\"o}rger, Katja},
  title     = {Hydrothermal time model of germination : parameters for 36 Mediterranean annual species based on a simplified approach},
  url       = {http://nbn-resolving.de/urn:nbn:de:kobv:517-opus-12406},
  year      = {2006},
  abstract  = {Germination rates and germination fractions of seeds can be predicted well by the hydrothermal time (HTT) model. Its four parameters hydrothermal time, minimum soil temperature, minimum soil moisture, and variation of minimum soil moisture, however, must be determined by lengthy germination experiments at combinations of several levels of soil temperature and moisture. For some applications of the HTT model it is more important to have approximate estimates for many species rather than exact values for only a few species. We suggest that minimum temperature and variation of minimum moisture can be estimated from literature data and expert knowledge. This allows to derive hydrothermal time and minimum moisture from existing data from germination experiments with one level of temperature and moisture. We applied our approach to a germination experiment comparing germination fractions of wild annual species along an aridity gradient in Israel. Using this simplified approach we estimated hydrothermal time and minimum moisture of 36 species. Comparison with exact data for three species shows that our method is a simple but effective method for obtaining parameters for the HTT model. Hydrothermal time and minimum moisture supposedly indicate climate related germination strategies. We tested whether these two parameters varied with the climate at the site where the seeds had been collected. We found no consistent variation with climate across species, suggesting that variation is more strongly controlled by site-specific factors.},
  language  = {en}
}
@misc{Koechy2006,
  author    = {K{\"o}chy, Martin},
  title     = {Photodegradation of grass litter in semi-arid grasslands : a global perspective},
  url       = {http://nbn-resolving.de/urn:nbn:de:kobv:517-opus-12006},
  year      = {2006},
  abstract  = {In a recent contribution in Nature (vol. 442, pp. 555-558) Austin \& Vivanco showed that sunlight is the dominant factor for decomposition of grass litter in a semi-arid grassland in Argentine. The quantification of this effect was portrayed as a novel finding. I put this result in the context of three other publications from as early as 1980 that quantified photodegradation. My synopsis shows that photodegradation is an important process in semi-arid grasslands in South America, North America and eastern Europe.},
  language  = {en}
}
@inproceedings{RossmanithBlaumKeiletal.2006,
  author    = {Rossmanith, Eva and Blaum, Niels and Keil, Manfred and Langerwisch, F. and Meyer, Jork and Popp, Alexander and Schmidt, Michael and Schultz, Christoph and Schwager, Monika and Vogel, Melanie and Wasiolka, Bernd and Jeltsch, Florian},
  title     = {Scaling up local population dynamics to regional scales},
  url       = {http://nbn-resolving.de/urn:nbn:de:kobv:517-opus-7320},
  year      = {2006},
  abstract  = {In semi-arid savannas, unsustainable land use can lead to degradation of entire landscapes, e.g. in the form of shrub encroachment. This leads to habitat loss and is assumed to reduce species diversity. In BIOTA phase 1, we investigated the effects of land use on population dynamics on farm scale. In phase 2 we scale up to consider the whole regional landscape consisting of a diverse mosaic of farms with different historic and present land use intensities. This mosaic creates a heterogeneous, dynamic pattern of structural diversity at a large spatial scale. Understanding how the region-wide dynamic land use pattern affects the abundance of animal and plant species requires the integration of processes on large as well as on small spatial scales. In our multidisciplinary approach, we integrate information from remote sensing, genetic and ecological field studies as well as small scale process models in a dynamic region-wide simulation tool. <hr> Interdisziplin{\"a}res Zentrum f{\"u}r Musterdynamik und Angewandte Fernerkundung Workshop vom 9. - 10. Februar 2006.},
  language  = {en}
}
@inproceedings{PoppBlaumDomptailetal.2006,
  author    = {Popp, Alexander and Blaum, Niels and Domptail, Stephanie and Herpel, Nicole and Gr{\"o}ngr{\"o}ft, Alexander and Hoffman, T. T. and J{\"u}rgens, Norbert and Milton, Sue and Nuppenau, Ernst-August and Rossmanith, Eva and Schmidt, Michael and Vogel, Melanie and Vohland, Katrin and Jeltsch, Florian},
  title     = {From satellite imagery to soil-plant interactions},
  url       = {http://nbn-resolving.de/urn:nbn:de:kobv:517-opus-7302},
  year      = {2006},
  abstract  = {Decisions for the conservation of biodiversity and sustainable management of natural resources are typically related to large scales, i.e. the landscape level. However, understanding and predicting the effects of land use and climate change on scales relevant for decision-making requires to include both, large scale vegetation dynamics and small scale processes, such as soil-plant interactions. Integrating the results of multiple BIOTA subprojects enabled us to include necessary data of soil science, botany, socio-economics and remote sensing into a high resolution, process-based and spatially-explicit model. Using an example from a sustainably-used research farm and a communally used and degraded farming area in semiarid southern Namibia we show the power of simulation models as a tool to integrate processes across disciplines and scales.},
  language  = {en}
}
@misc{KoechyWilson2004,
  author    = {K{\"o}chy, Martin and Wilson, Scott D.},
  title     = {Variation in nitrogen deposition and available soil nitrogen in a forest-grassland ecotone in Canada},
  url       = {http://nbn-resolving.de/urn:nbn:de:kobv:517-opus-5768},
  year      = {2004},
  abstract  = {Regional variation in nitrogen (N) deposition increases plant productivity and decreases species diversity, but landscape- or local-scale influences on N deposition are less well-known. Using ion-exchange resin, we measured variation of N deposition and soil N availability within Elk Island National Park in the ecotone between grassland and boreal forest in western Canada. The park receives regionally high amounts of atmospheric N deposition (22 kg ha⁻¹ yr⁻¹). N deposition was on average higher ton clayrich luvisols than on brunisols, and areas burned 1 - 15 years previously received more atmospheric N than unburned sites. We suggest that the effects of previous fires and soil type on deposition rate act through differences in canopy structure. The magnitude of these effects varied with the presence of ungulate grazers (bison, moose, elk) and vegetation type (forest, shrubland, grassland). Available soil N (ammonium and nitrate) was higher in burned than unburned sites in the absence of grazing, suggesting an effect of deposition. On grazed sites, differences between fire treatments were small, presumably because the removal of biomass by grazers reduced the effect of fire. Aspen invades native grassland in this region, and our results suggest that fire without grazing might reinforce the expansion of forest into grassland facilitated by N deposition.},
  language  = {en}
}
@article{Gzik2003,
  author    = {Gzik, Axel},
  title     = {Vitalit{\"a}t und Konkurrenzkraft charakteristischer Pflanzenarten von Feuchtstandorten der Unteren Havelaue},
  series = {Brandenburgische Umwelt-Berichte : BUB ; Schriftenreihe der Mathematisch-Naturwissenschaftlichen Fakult{\"a}t der Universit{\"a}t Potsdam},
  volume    = {13},
  journal   = {Brandenburgische Umwelt-Berichte : BUB ; Schriftenreihe der Mathematisch-Naturwissenschaftlichen Fakult{\"a}t der Universit{\"a}t Potsdam},
  issn      = {1434-2375},
  url       = {http://nbn-resolving.de/urn:nbn:de:kobv:517-opus-4046},
  pages     = {72 -- 81},
  year      = {2003},
  language  = {de}
}
@article{Scheffler2001,
  author    = {Scheffler, Christiane},
  title     = {Bewegungsmuster in Alltagssituationen},
  series = {Brandenburgische Umwelt-Berichte : BUB ; Schriftenreihe der Mathematisch-Naturwissenschaftlichen Fakult{\"a}t der Universit{\"a}t Potsdam},
  volume    = {10},
  journal   = {Brandenburgische Umwelt-Berichte : BUB ; Schriftenreihe der Mathematisch-Naturwissenschaftlichen Fakult{\"a}t der Universit{\"a}t Potsdam},
  issn      = {1434-2375},
  url       = {http://nbn-resolving.de/urn:nbn:de:kobv:517-opus-3933},
  pages     = {94 -- 99},
  year      = {2001},
  language  = {de}
}
@article{NothGreilScheffleretal.2001,
  author    = {Noth, Veronika and Greil, Holle and Scheffler, Christiane and Lange, E.},
  title     = {Strategien bei der Handhabung von Verschl{\"u}ssen im Kleinkind- und Vorschulalter},
  series = {Brandenburgische Umwelt-Berichte : BUB ; Schriftenreihe der Mathematisch-Naturwissenschaftlichen Fakult{\"a}t der Universit{\"a}t Potsdam},
  volume    = {10},
  journal   = {Brandenburgische Umwelt-Berichte : BUB ; Schriftenreihe der Mathematisch-Naturwissenschaftlichen Fakult{\"a}t der Universit{\"a}t Potsdam},
  issn      = {1434-2375},
  url       = {http://nbn-resolving.de/urn:nbn:de:kobv:517-opus-3916},
  pages     = {77 -- 86},
  year      = {2001},
  language  = {de}
}
@article{Greil2001,
  author    = {Greil, Holle},
  title     = {Wachstum und Variabilit{\"a}t im K{\"o}rperbau und ihre Ber{\"u}cksichtigung bei industriellen Gr{\"o}ßensystemen},
  series = {Brandenburgische Umwelt-Berichte : BUB ; Schriftenreihe der Mathematisch-Naturwissenschaftlichen Fakult{\"a}t der Universit{\"a}t Potsdam},
  volume    = {10},
  journal   = {Brandenburgische Umwelt-Berichte : BUB ; Schriftenreihe der Mathematisch-Naturwissenschaftlichen Fakult{\"a}t der Universit{\"a}t Potsdam},
  issn      = {1434-2375},
  url       = {http://nbn-resolving.de/urn:nbn:de:kobv:517-opus-3901},
  pages     = {62 -- 76},
  year      = {2001},
  language  = {de}
}
@article{Greil2001,
  author    = {Greil, Holle},
  title     = {K{\"o}rpermaße 2000},
  series = {Brandenburgische Umwelt-Berichte : BUB ; Schriftenreihe der Mathematisch-Naturwissenschaftlichen Fakult{\"a}t der Universit{\"a}t Potsdam},
  volume    = {10},
  journal   = {Brandenburgische Umwelt-Berichte : BUB ; Schriftenreihe der Mathematisch-Naturwissenschaftlichen Fakult{\"a}t der Universit{\"a}t Potsdam},
  issn      = {1434-2375},
  url       = {http://nbn-resolving.de/urn:nbn:de:kobv:517-opus-3889},
  pages     = {23 -- 53},
  year      = {2001},
  language  = {de}
}
@article{Greil2001,
  author    = {Greil, Holle},
  title     = {Wie weit sind wir der DIN 33402 entwachsen?},
  series = {Brandenburgische Umwelt-Berichte : BUB ; Schriftenreihe der Mathematisch-Naturwissenschaftlichen Fakult{\"a}t der Universit{\"a}t Potsdam},
  volume    = {10},
  journal   = {Brandenburgische Umwelt-Berichte : BUB ; Schriftenreihe der Mathematisch-Naturwissenschaftlichen Fakult{\"a}t der Universit{\"a}t Potsdam},
  issn      = {1434-2375},
  url       = {http://nbn-resolving.de/urn:nbn:de:kobv:517-opus-3870},
  pages     = {7 -- 22},
  year      = {2001},
  language  = {de}
}
@article{BeierHinrichsenKlatt1997,
  author    = {Beier, Wolfgang and Hinrichsen, A. and Klatt, Reimund},
  title     = {{\"O}kofaunistische Untersuchungen auf ausgew{\"a}hlten Truppen{\"u}bungspl{\"a}tzen Brandenburgs},
  series = {Brandenburgische Umwelt-Berichte : BUB ; Schriftenreihe der Mathematisch-Naturwissenschaftlichen Fakult{\"a}t der Universit{\"a}t Potsdam},
  volume    = {1},
  journal   = {Brandenburgische Umwelt-Berichte : BUB ; Schriftenreihe der Mathematisch-Naturwissenschaftlichen Fakult{\"a}t der Universit{\"a}t Potsdam},
  issn      = {1434-2375},
  url       = {http://nbn-resolving.de/urn:nbn:de:kobv:517-opus-2788},
  pages     = {130 -- 137},
  year      = {1997},
  language  = {de}
}