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Diversity and Ecophysiology of Cyanobacterial Mat Communities in Arctic and Antarctic Ecosystems

Diversity and Ecophysiology of Cyanobacterial Mat Communities in Arctic and Antarctic Ecosystems

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KLEINTEICH, Julia, 2013. Diversity and Ecophysiology of Cyanobacterial Mat Communities in Arctic and Antarctic Ecosystems

@phdthesis{Kleinteich2013Diver-22664, title={Diversity and Ecophysiology of Cyanobacterial Mat Communities in Arctic and Antarctic Ecosystems}, year={2013}, author={Kleinteich, Julia}, address={Konstanz}, school={Universität Konstanz} }

eng deposit-license Diversität und Ökophysiologie cyanobakterieller Mattengemeinschaften in den Ökosystemen der Arktis und Antarktis 2013-04-09T08:35:30Z Kleinteich, Julia Kleinteich, Julia 2013 Cyanobacteria (more commonly known as blue-green algae) are photosynthetic bacteria with a worldwide distribution. They are most common in the freshwater environment but are also present in many marine waters. As they are pioneer-organisms and they can often be found in extreme environments. They also constitute the dominant primary producers in the terrestrial Polar Regions and therefore have a pivotal role in polar ecosystems. In freshwater streams, ponds, and lakes that are formed during the polar summer, they occur as benthic or floating mats several millimetres to centimetres thick, sometimes covering several square meters. These mats are the nutritional basis and the micro-habitat for several other types of organisms (primarily proto- and metazoa).<br />This study describes the species diversity of cyanobacterial mat communities from the Arctic and Antarctic that were collected prior to and during the thesis using molecular phylogenetic techniques. The characterization was accomplished by morphological identification as well as the sequencing of the ribosomal RNA genes and the more variable ITS-region (intergenic spacer region). Conventional molecular biological methods (clone-library, automated ribosomal intergenic spacer analysis (ARISA)) were applied as well as „Next-Generation-Sequencing“ based on the 454® technology. The latter allows thousands of sequences to be obtained from a single sample. Using these methods a comprehensive picture of the phylogenetic diversity could be obtained and mats from the Arctic and the Antarctic region compared with and within each other.<br /><br />Cyanobacteria synthesize multiple secondary metabolites, some of which are toxic to most higher organisms including humans. Health hazards or even life threatening incidents regularly occur in the temperate and tropical regions during bloom events (mass-occurrences of cyanobacteria).<br /><br />This study demonstrated that cyanobacterial toxins are present in cyanobacterial mats of the Arctic and the Antarctic. In the Arctic two cyanobacterial toxins were recorded for the first time: An unusual variant of the cyanobacterial hepatotoxin microcystin. This toxin acts as an inhibitor of cellular protein phosphatases (PP 1, 2A, 4 und 5). The second toxin identified was the neurotoxic saxitoxin which inhibits neuronal signal propagation by blocking Na2+ channels. Cylindrospermopsin, a protein synthesis inhibitor was detected for the first time in the Antarctic. These results indicate that the potential for toxin production in the cyanobacterial communities of the Arctic and Antarctic is higher than previously thought.<br /><br />The Polar Regions are currently subject to profound change: Temperatures are increasing at higher rates than anywhere else on the planet. In is expected that a consequence of climate change will be that the composition of the mat communities comprising cyanobacteria and associated proto- and metazoans, are affected. Because of their simple trophic structure and their sensitivity to change, they are an ideal model system for the exploration of climate induced changes. Therefore the effect of climate change on the diversity and toxicity of cyanobacterial mats was studied here in a laboratory based approach. Increased temperatures (8 - 16 °C) resulted in a higher concentration of microcystin as well as in structural changes of the community composition. Based on these results as well as on previous studies, it can be expected that climate change will affect the toxicity of cyanobacteria in the Polar Regions and in lower latitudes. A general increase and a wider distribution of toxic cyanobacteria, as well as an increase of the rate of toxin production may be expected. Diversity and Ecophysiology of Cyanobacterial Mat Communities in Arctic and Antarctic Ecosystems

Dateiabrufe seit 01.10.2014 (Informationen über die Zugriffsstatistik)

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