Free amino acid composition in blood and muscle of the gobi Precottus glehni at the period of preparation and completion of hibernation

Abstract

The freshwater fish gobi Preccottus glehni survives after wintering in ponds frozen in winter till the very bottom. In adaptation of poikilothermal animals to wintering at near-zero temperatures, an essential role is played by free amino acids; accumulation of a large amount of some particular acid at the period of preparation to the state of hibernation can indicate the protective role of this acid in the low-temperature adaptation. In the present work it has been shown that as soon as by the end of August, in the gobi muscle, the taurine concentration increases three times as compared with that in July, the taurine pool after this reaching 50% of the total pool of free amino acids in the muscle tissue. During December and after the 3-month hibernation in ice, it exceeds the April and July levels 8 and 4 times, respectively, and amounts to 50% of the total free amino acid pool for muscle and to 40% for blood. Several days prior to the beginning of winter hibernation under natural conditions, both in blood and in muscle, there is revealed disappearance or a sharp fall of concentration of essential amino acids. An essential peculiarity of the change in the free amino acid composition after hibernation was a significant rise of alanine concentration in muscle—3.5 times as compared with July and 1.4–1.8 times as compared with changes in December. The total free amino acid pool in muscle in December as compared with that in July increased almost 1.5 times (34.76 ± 1.12 μmol/g wet weight), while after hibernation—2 times. Peculiarities of taurine accumulation long before the beginning of winter cold allow suggesting that role of taurine consists in providing a possibility of existence of eurythermal fish at near-zero temperature.