Low-Temperature Adaptation of the Rana temporaria Gastrocnemius Muscle at the Onset of Anabiosis

A study of the effect of a seasonal decrease in ambient temperature on the composition of free amino acids and ninhydrin-positive secondary metabolites in gastrocnemius muscles of the frog Rana temporaria revealed that at the onset of winter anabiosis, as compared to the summer season, the alanine pool increased from 2.43 to 6.10 µmol/g w.w., and the 3-methylhistidine pool rose from 1.52 to 2.80 µmol/g w.w. For the first time, muscles of poikilothermic animals (namely, frogs) were found to contain cysteic acid and phosphoethanolamine, the level of which increased by the onset of hibernation, particularly for cysteic acid (from 0.91 to 2.15 µmol/g w.w.). The taurine level proved to be far lower compared to animals both of lower and higher phylogenetic ranks, but by the onset of hibernation it increased almost threefold. Presumably, the accumulation of the above metabolites relates to their protective role at temperatures that are extremely low for the survival of R. temporaria.