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Abstract |
Isolation, temperature and thermal steadiness provided by Antarctic Ocean make it a particularly favourable environment for studying of genetic adaptations to cold and stenothermy. The impact, on a very long-range, of Antarctic climate, has led, for several species, to the loss of the universal Heat Shock Response (HSR). Such an evolution results, on the molecular level, from changes in function and/or nature of Hsps, especially in the subfamily of Hsps70. The characterization of three Hsps70 genes and, at least, one Hsp90 in krill Euphausia superba, a key-species of this regional trophic web, authorized a functional study, involving RT-qPCR technics, of Hsps regulation in response to a heat stress. This approach showed the preservation of the HSR in E. superba, despite the fact that this species inhabits Antarctic Ocean for several million years. Even though conditions for transcriptional inducibility or constitutivity remain hard to determine, especially for Hsps70, results from E. superba experiments, juxtaposed to current knowledge about krill ecology and physiology, led to hypothesis about HSR preservation in a thermally cold and steady environment. These findings can also be of great interest for larger studies about global warming impact on Antarctic fauna. A parallel study at structural and phylogenetic level led to confirm functional results. |
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