Muneo Sameshima

Pigmentation of prawn (Penaeus japonicus) with carotenoids: I. Effect of dietary astaxanthin, β-carotene and canthaxanthin on pigmentation

Abstract In experiment 1, four diets (control, astaxanthin, β -carotene and canthaxanthin) were fed to single groups of prawns (mean weight, 8.5 g) for 8 weeks. Dietary astaxanthin was incorporated into body tissues at a higher rate than the other dietary carotenoids. The free astaxanthin concentrations of the prawn after 8 weeks were the same for the four diet groups. Dietary astaxanthin, β -carotene and canthaxanthin were deposited in prawn body tissue mainly as astaxanthin esters. In experiment 2, five diets supplemented with astaxanthin at levels of 0, 50, 100, 200 and 400 ppm were fed to single groups of prawns (mean weight, 3.7 g) for 8 weeks. Total carotenoid and astaxanthin ester concentrations of the prawn after 8 weeks increased with increasing dietary astaxanthin level up to 200 ppm. The same final total carotenoid or astaxanthin ester concentrations were found with the 200 and 400 ppm feed supplements. Feeding various pigments did not result in any notable changes in daily feed intake, percent gain or feed efficiency.

Occurrence of Nα-acetylhistidine in the muscle and deacetylation by several tissues of nile tilapia (oreochromis niloticus)

Abstract 1. 1. Nα- Acetyl - l - histidine was identified in protein-free extracts of muscle of Nile tilapia ( Oreochromis niloticus ), and this substance was the major component (2.8 μmol/g tissue) of the imidazole pool in the muscle of the fish. 2. 2. High Nα -acetylhistidine-deacetylating activity was found in crude enzyme solutions prepared from kidney, brain, liver and eye of the fish, and kidney was the richest source of this activity. 3. 3. After intraperitoneal administration of Nα -acetylhistidine to the fish, a drastic increase in kidney histidine concentration was observed after 2 hr. 4. 4. It is supposed that exogenously administered Nα -acetylhistidine is transported to kidney via blood plasma, and effectively deacetylated to histidine by the enzyme(s) of the kidney.