Freezing resistance in Antarctic and Arctic fishes: its relation to mode of life, ecology and evolution

Woehrmann A.

Date de parution: décembre 1997
Volume: 21
Number: 4
Pagination: 423-442
Editeur: Société Française d'Ichtyologie
doi: https://doi.org/10.26028/cybium/1997-214-010
Résumé

Biological antifreezes are present in most Antarctic and Arctic fishes and lower the freezing point of most of their body fluids below the freezing point of seawater (‑1.9°C), without substantially increasing their osmotic pressure. In the blood of Antarctic notothenioid and Arctic gadiform fishes, freezing is inhibited by antifreeze glycopeptides (AFGP). These anti­freeze molecules are built up of repeating tripeptide units (Ala-Ala-Thr)n, to which the disaccharide b-D-galactosyl-(1->3)a-N-acetyl-D-galactosamine is linked through the hydroxyl oxygen of the threonyl residue. Species of Liparididae, Zoarcidae, Cottidae and Pleuronectidae in the Antarctic, Arctic and northern-boreal waters synthesize only unglycosylated antifreeze peptides (AFP). The level of antifreeze concentration was dependent on the ambient water temperature, the depth of distribution, the life history and the level of activity of the species. Whereas the synthesis of AFGP in Antarctic and Arctic fish species appear to regulate by the ambient water temperature, the AFP production in Arctic fish and probably in non-notothenioid Antarctic fish will be controlled by photoperiod. Surprisingly, detectable concentrations of AFGPs in perciform fish of the Antarctic and gadiform fish of the Arctic and Antarctic could illustrate, that before the continental drift occurred a precursor glycopeptid existed, and that the existence of freezing resistance in some species reflects the past glaciation. The wide distribution and high heterogeneity of AFPs point to the assumption that these peptides are results of cold shock stress responses in a different way.

Mots-clés: Activity - AFGP - Antarctic Ocean - Antifreeze - Arctic Ocean - Evolution - Gadiformes - Metabolism - Mode of life - Notothenioidei - PN - PS
PDF visible pour tous