Effects of Cold Shock on Responses of Phosphomonoesters and Free Amino Acids in Phospholipid-Rich Organs in the Amur Sleeper Perccottus Glehni

Abstract

Similarities and differences were found in the mechanisms of adaptation of the brain and liver to cold shock in the freshwater fish Perccottus glehni. The quantity of phosphoethanolamine in the brain on day 4 of cold shock at +4°C increased 84-fold from the level in controls (+20°C), accounting for 22.3% of the total pool of free amino acids and ninhydrin-positive compounds. Phosphoserine was absent from the brain at +20°C, but cold shock initiated its accumulation to 1.8% of the total pool. The taurine pool at +4°C decreased from 28.3 to 20% of the total pool, yielding first place to phosphoethanolamine. However, in the liver, phosphoethanolamine (PE) and phosphoserine (PS) were not seen in the free form either in controls or at 4°C. The dominant amino acid in the liver at both temperatures was taurine, the quantity at +4°C being significantly increased. Th glutamate pool decreased nine-fold at +4°C. It is suggested that the intense accumulation of PE and PS in the brain at low temperatures is evidence of the specific features of the adaptation of the neuron membrane, reflecting quantitative changes in phospholipids, possibly including sphingosine-1-phosphate.