Issartel Julien, Renault David, Voituron Yann, Bouchereau Alain, Vernon Philippe, Hervant Frédéric
Ecologie des Hydrosystèmes Fluviaux, UMR CNRS 5023, Université Lyon 1, 69622 Villeurbanne Cedex, France.
J Exp Biol. 2005 Aug;208(Pt 15):2923-9. doi: 10.1242/jeb.01737.
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 degrees C, 3 degrees C and -2 degrees 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 degrees 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 degrees 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.
研究了水生、地下（即穴居）甲壳类动物莱茵尼菲虾（Niphargus rhenorhodanensis）和维氏尼菲虾（Niphargus virei）以及形态相近的水生、地表栖息（即地表生活）甲壳类动物河蚬（Gammarus fossarum）在适应12摄氏度、3摄氏度和零下2摄氏度时多元醇、糖类和游离氨基酸（FAA）体内含量的变化。随着温度降低，河蚬的丙氨酸和谷氨酰胺水平显著增加，而海藻糖体内含量仅在零下2摄氏度时高于对照水平。维氏尼菲虾的丙氨酸和甘氨酸有适度增加，且该物种的海藻糖水平未观察到变化。相比之下，莱茵尼菲虾是唯一总FAA库显著增加的物种，主要原因是丙氨酸、甘氨酸、精氨酸和谷氨酰胺的积累。该物种的海藻糖体内含量也随着温度降低而逐渐增加。一些耐寒变温动物对寒冷的代谢反应与在莱茵尼菲虾中观察到的相同。先前的一项比较研究表明，穴居的莱茵尼菲虾在零下2摄氏度时的存活时间（Lt50）分别比穴居的维氏尼菲虾和地表生活的河蚬高26.3倍和2.6倍。因此，甲壳类动物的FAA和海藻糖水平与其各自的耐寒性相关。这两种穴居生物对寒冷的代谢反应存在差异是出乎意料的，因为它们都生活在热缓冲的生物群落中。考虑到所研究的两种地下甲壳类动物的当前分布区域我们假设穴居的莱茵尼菲虾中发现的耐寒性可能与其第四纪冰川时期的生物地理历史相关。
