Molecular adaptation and thermal plasticity in a cold-adapted Antarctic fish
Evolutionary adaptation and the connected acclimation capacity of species to changing environmental conditions represents one of the key factors in the composition and dynamics of any ecosystem. In marine environments temperature is one of the major factors defining the aquatic fauna. In respect to...
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| Format: | Thesis |
| Language: | unknown |
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Staats- und Universitätsbibliothek Bremen
2013
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| Online Access: | https://epic.awi.de/id/eprint/32672/ http://elib.suub.uni-bremen.de/edocs/00103081-1.pdf https://hdl.handle.net/10013/epic.41362 |
| Summary: | Evolutionary adaptation and the connected acclimation capacity of species to changing environmental conditions represents one of the key factors in the composition and dynamics of any ecosystem. In marine environments temperature is one of the major factors defining the aquatic fauna. In respect to progressing climate change the question arises how individual species react to higher temperatures and how this affects the entire ecosystem. Species that are highly specialized on stable environmental conditions seem to be especially vulnerable. This thesis characterizes the Antarctic eelpout Pachycara brachycephalum (Pappenheim, 1912) in regards to its adaptation to low habitat temperatures as well as its capacity to acclimate to higher temperatures at the molecular level. A cDNA library was established and subjected to high-throughput sequencing to provide a basis for sequence analyses. To characterize differences between a cold-adapted and a eurythermal species, an already existing cDNA library of the closely related congener Zoarces viviparus (Linnaeus, 1758) was included in large-scale comparisons. The repertoire of functional genes reflected cold-adaptation features of cellular metabolism in P. brachycephalum, e.g. through a higher ratio of ubiquitin–related genes. These genes are of great importance in cold-adaptation and counter the cold denaturation of proteins. Furthermore, the amino acid sequences of orthologous proteins displayed differences between the eury- and the stenotherm. The observed position-specific interchanges in P. brachycephalum highly conform with the flexibility hypothesis. According to this hypothesis a protein may be destabilized in its three-dimensional structure by minimal changes within the amino acid sequence. This destabilization sustains reaction kinetics in the cold. In addition, differences were noted in the encoding of amino acids at DNA level. Within homologous proteins of P. brachycephalum amino acids are encoded with a preference for AT-richer triplets on the third codon ... |
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