Seasonal Variation of Extractive Nitrogeneous Constituents in the Muscle of the Ascidian Halocynthia roretzi

Abstract

Seasonal variation of extractive nitrogenous components in the muscle of the cultured ascidian Halocynthia roretzi was investigated in the specimens collected bimonthly from January 1983 to January 1984 at Okkirai Bay, Iwate Prefecture. The ascidian muscle extracts were characterized by being rich in free amino acids, especially in taurine, proline, glutamic acid, glycine, alanine and histidine. Considerable amounts of quaternary ammonium bases such as glycinebetaine and homarine were found, but arginine and creatine were scanty.
Extractive nitrogen, most free amino acids, and nucleotides and related compounds showed a pronounced annual cycle with maximum in summer and/or autumn and minimum in winter.
The nitrogen of free amino acids accounted for 47-67% of extractive nitrogen, which was followed by those of glycinebetaine(9-19%), nucleotides and related compounds(5-9%), and other constituents such as homarine, trigonelline, trimethylamine oxide, trimethylamine, creatine and creatinine(5-14%). The sum total amounted to 80-90% of extractive nitrogen, but was fairly lower than those so far found by us in the muscles of other marine animals.