Impact of Seasonal Temperature Decrease and Cold Shock on the Composition of Free Amino Acids and Phosphomonoethers in Various Organs of Amur Sleeper Percottus glenii (Eleotridae)

Abstract

The Amur sleeper Perccottus glenii is used as a model for investigation of free amino acids' responses in various organs to changes of temperature during the annual cycle and under a prolonged cold shock. Phosphoethanol and phosphoserine are found during seasonal decrease of temperature and at the fourth day of cold shock in the brain. Up to the beginning of winter, the pool of phosphoethanoamine increases by 94 times. That of taurine, which is in negative reciprocal relationship with phosphoethanoamine, decreases at the seasonal drop of temperature and temperature shock. In December, fourfold increase of the taurine level was found in muscles (56% of the total pool of amino acids), while eightfold in plasma (43%). The cold shock does not stimulate accumulation of taurine in plasma, muscles, and brain and only slightly increases its content in the liver. In contrast to the constantly increasing taurine content in the plasma and muscles from April to December, the pools of proteinogenic amino acids fluctuate during the annual cycle, considerably increasing after hypobiosis and at the fourth day after the cold shock. The specific decrease of the large pool of histidine in the brain by 16.7 times is found at the fourth day of the shock, while it is by 4.8 times in muscle in winter. It is supposed that phosphoethanol (in the brain) and taurine (in other organs) may be protectors in adaptation of fish to low temperatures.