Comparison of nutrient composition of gonads and coelomic fluid of green sea urchin Strongylocentrotus droebachiensis

Liyana-Pathirana, Chandrika and Shahidi, Fereidoon and Whittick, Alan (2002) Comparison of nutrient composition of gonads and coelomic fluid of green sea urchin Strongylocentrotus droebachiensis. Journal of Shellfish Research, 21 (2). pp. 861-870. ISSN 0730-8000

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Abstract

The compositional characteristics of sea urchin gonads and coeloniic lluid from Stnmgylocemnitus droehuchiensis harvested in the coasts of Newfoundland and thereafter reared in an aquaculture facility and fed on a Laminaria diet for a 3-week period, were assessed. Evaluations were performed on the basis of proximate composition, lipid class distribution, fatty acid composition, total and free amino acid composition, and contents of nucleic acids and carotenoids. Noticeable changes existed between proximate composition of sea urchin gonads and coelomic fluid. Moisture content was 74.7 + 0.04 and 96.5 ± 0.03% in gonads and coelomic fluid, respectively. Gonads contained very high levels of lipids, proteins, and carbohydrates; whereas, these were present at very low levels in the coelomic fluid. Major nonpolar lipid classes were triacylglycerols (TAG), free fatty acids (FFA). and sterols (ST) while dommant polar lipid classes were phosphatidylcholine (PC), phosphatidylethanolamine (PE). sphingomyelin/ lysophosphatidylcholine (SM/LPC). and phosphatidylserine / phosphatidylinositol (PS/PlI in both the gonads and the coelomic fluid. Major saturated fatty acids (SPA) were 14;0 and 16:0; whereas. 20:ln-15 was the main monounsaturated fatty acid (MUFA) present. Furthermore, 20:5n-3 (eicosapentaenoic acid, EPA) was the dominant polyunsaturated fatty acid (PUFA) in the gonads and the coelomic fluid. The total amino acid (TAA) and free amino acid (FAA) profiles were dominated by glycine. The total FAA content was much higher in the gonads than in the coelomic fluid. In addition, the total carotenoid content of sea urchin gonads was approximately 6.4 times greater than that of coelomic fluid. Hence, most of the carotenoids were concentrated in the gonadal tissue. Echininone and fucoxanthin were the dominant carotenoids in the gonads and the coelomic fluid, respectively. The content of deoxyribonucleic acid (DNA) and ribonucleic acid (RNA) was much higher in the gonad than in the coelomic fluid, thus indicating greater biomass and protein synthetic activity in the former tissue. The present study demonstrates that sea urchin gonads have much in common with sea urchin coelomic fluid on a qualitative basis. However, there were marked quantital;ve differences between the two tissues.

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