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First published online July 25, 2005
Journal of Experimental Biology 208, 2923-2929 (2005)
Published by The Company of Biologists 2005
doi: 10.1242/jeb.01737

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Metabolic responses to cold in subterranean crustaceans

Julien Issartel^1,*, David Renault², Yann Voituron³, Alain Bouchereau⁴, Philippe Vernon² and Frédéric Hervant¹

¹ Ecologie des Hydrosystèmes Fluviaux, UMR CNRS 5023, Université Lyon 1, 69622 Villeurbanne Cedex, France
² Fonctionnement des Ecosystèmes et Biologie de la Conservation, UMR CNRS 6553, Université Rennes 1, 35042 Rennes Cedex, France
³ Physiologie des Régulations Energétiques, Cellulaires et Moléculaires, UMR CNRS 5123, Université Lyon 1, 69622 Villeurbanne Cedex, France
⁴ Osmoadaptation et Métabolismes de Stress, UMR CNRS 6026, Université Rennes 1, 35042 Rennes Cedex, France

^* Author for correspondence (e-mail: julien.issartel{at}univ-lyon1.fr)

Accepted 7 June 2005

Changes in polyol, sugar and free amino acid (FAA) body contents were investigated in the aquatic, subterranean (i.e. hypogean) crustaceans Niphargus rhenorhodanensis and Niphargus virei and in a morphologically close aquatic, surface-dwelling (i.e. epigean) crustacean Gammarus fossarum acclimated to 12°C, 3°C and –2°C. With decreasing temperature, G. fossarum significantly increased its alanine and glutamine levels, while trehalose body content was found to increase above control levels only at –2°C. N. virei showed moderate increases of alanine and glycine, and no change in trehalose level was observed in this species. By contrast, N. rhenorhodanensis was the only species showing a significant rise in its total FAA pool, mainly explained by alanine, glycine, arginine and glutamine accumulations. This species also gradually increased its trehalose body content with decreasing temperature. Several cold-hardy ectotherms show metabolic responses to cold that are identical to those observed in N. rhenorhodanensis. A previous comparative study showed that the hypogean N. rhenorhodanensis exhibited a survival time (Lt₅₀) at –2°C that was 26.3 times and 2.6 times higher than the hypogean N. virei and the epigean G. fossarum, respectively. Thus, crustacean levels of FAA and trehalose were correlated with their respective cold tolerances. Such differences in metabolic responses to cold in both hypogean organisms were unexpected since they both live in thermally buffered biotopes. Considering the current distribution areas of the two subterranean crustaceans studied, we assume that the cold hardiness found in the hypogean N. rhenorhodanensis could be correlated with its biogeography history during the quaternary glaciations.

Key words: hypogean crustacean, cold hardiness, free amino acid, trehalose, life history

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				J. Issartel, Y. Voituron, V. Odagescu, A. Baudot, G. Guillot, J.-P. Ruaud, D. Renault, P. Vernon, and F. Hervant Freezing or supercooling: how does an aquatic subterranean crustacean survive exposures at subzero temperatures? J. Exp. Biol., September 1, 2006; 209(17): 3469 - 3475. [Abstract] [Full Text] [PDF]