Sexual differences in the composition and metabolism of lipids in the mantle of the mussel Mytilus galloprovincialis LMK (Mollusca: Bivalvia)

Abstract Studies carried out on the different species of lipids in the mantle of mussels ( M. galloprovincialis ) during the prespawning period have revealed significant differences between males and females. 1. 1. The total lipid content of female mantle is twice as high as in the male mantle, the difference resulting from the triacylglycerides (lipidic granules in oocytes). Total phospholipids and cholesterol are similar in both sexes as is the occurrence of fatty acids 16:0, 20:5ω3 and 22:6ω3. 2. 2. The differences between 16:0/16:1 ratio in the phospholipids of females and males show that the desaturase enzyme may not have the same activity in both sexes. The acylation-deacylation cycle for the phospholipid biosynthesis is probably highly active in this tissue. 3. 3. Experiments carried out with labeled glycerol have shown that in the male mantle, phosphatidylinositol (PI) and triacylglycerols have a higher and phosphatidylcholine (PC) a lower renewal rate compared to female mantle. The ratio of the specific activities of PI/PC is correlated with sexual stages in the female mantle and increases during vitellogenesis.