Physiological and chemical studies on the nitrogenous components in the extracts of aquatic animals

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The present co-operative studies were undertaken to elucidate the accumulation machanisms and physiological roles of the principal nitrogenous components in tissue extracts of aquatic animals, and the following results were obtained.1. Taurine, glycine, alanine and glycinebetaine contributed to the intracellular osmoregulation in a wide range of marine molluscs and crustaceans. Proline, glutamic acid, sarcosine, <beta> -alanine and/or homarine were also proved to be important osmoregulators in some tissues or in some species. 2. Homarine and trigonelline contents of tiger prawn and top shell were affected by the salinity of environmental seawater and by diets containing homarine. 3. During air exposure, strombine or rhodoic acid accumulated in the tissues of scallop and abalone. The muscular exercise resulted in significant increases of octopine and rhodoic acid in scallop and abalone, respectively. A new opine, <beta> -alanopine was isolated from the blood shell muscle. 4. Imidazole compounds such as histidine, carnosine and anserine were found to contribute greatly to the buffering capacity of fish muscles. 5. The tissue taurine levels of chum salmon, eel and guppy were affected by its level of diet. The taurine contents of the whole body and muscle of eel increased slightly when the fish was transferred into seawater. The trimethylamine oxide level of these fish was also affected by trimethylamine (TMA) content of diet and by salinity of environmental water. The enhancement of TMA monooxygenase activity was observed when eel and guppy were administered with TMA or adapted to seawater. 6. Carp and crucian carp synthesized creatine from glycine and arginine through glycocyamine, but some of the other fish did not; they could only convert glycocyamine to creatine. Red sea bream and rainbow trout were assumed to synthesize creatine at the larval stage and to incorporate most of it from foods after growing up.