Sexual Differences in Gonad Fatty Acid Compositions in Dominant Limpets Species from the Sanriku Coast in Northern Japan

Lipids in the gonads of two species of limpets from the Sanriku Coast in northern Japan were examined for lipid class and fatty acid composition. Dominant limpets were found to contain total lipids (TL) at, 1 to 2% and 5 to 6%, in the testes and ovaries, respectively. The testis was rich in phosphatidylcholine and phosphatidylethanolamine was found present. Triacylglycerol (TG) was the main constituent in the ovary. Significant differences were found in the proportion of fatty acid components of TL for those two organs. Icosapentaenoic acid (20:5n-3) was the most abundant fatty acid in the testis, with palmitic acid (16:0) being so in the ovary. Predominant fatty acids (>10% of total fatty acids in TL) generally contained 16:0, vaccenic acid (18:1n-7) and 20:5n-3 and 16:0, 18:1n-7 and arachidonic acid (20:4n-6) in the testis and ovary, respectively. The testis tends to be predominantly with amount of n-3 polyunsaturated fatty acids, 20:5n-3 being particularly high, at twice that in the ovary. The ovary contained much higher saturated fatty acids, compared to testis lipids. The quantitative distribution of fatty acids in lipid classes for male and female gonads was also determined. TG in the testis and ovary were rich in saturated fatty acid with abundant 16:0. The proportions of 20:4n-6 and 20:5n-3 in TG were low compared with those in TL and phospholipids (PL). PL contained more 20:4n-6 and 20:5n-3 than TG. PL in the testis were rich in 16:0, 18:1n-7 and 20:5n-3, and rich in 16:0, 20:4n-6 and 20:5n-3 in the ovary.