SEXUAL-DIFFERENTIATION OF REPRODUCTIVE TISSUE IN BIVALVE MOLLUSKS - IDENTIFICATION OF MALE ASSOCIATED POLYPEPTIDE IN THE MANTLE OF MYTILUS-GALLOPROVINCIALIS LMK

We have addressed the question of sexual reproductive tissue dimorphis m in bivalve molluscs, Mytilus galloprovincialis Lmk, which is a stabl e gonochoric species although with no apparent differences in gonad mo rphology of both sexes. At all periods of the annual cycle the protein s specific of male/female gonads were identified. One of these protein s, ''male-associated polypeptide'' with apparent MW 39 kDa (MAP-39), h as been biochemically and immunochemically characterized. MAP-39 conce ntration in male mature gonads achieved up to 10% of the total soluble protein while in female ones only traces of this protein could be det ected. In male mantle, MAP-39 expression was associated with the proce ss of gonad development and maturation as well as gamete spawning, alt hough this polypeptide has been localized in fibroblast-like cells, me mbrane of follicles and connective tissue matrix of the mantle but not in germinal cells.