MALE-PREDOMINANT CARBOXYLESTERASE EXPRESSION IN THE REPRODUCTIVE-SYSTEM OF MOLLUSKS AND INSECTS - IMMUNOCHEMICAL AND BIOCHEMICAL SIMILARITYBETWEEN MYTILUS MALE ASSOCIATED POLYPEPTIDE (MAP) AND DROSOPHILA SEX-SPECIFIC ESTERASE-S

We suggested that sexual differentiation oi the reproductive system in gonochoric species of invertebrates can be characterized by common mo lecular mechanisms in spite of high morphological divergences of repro ductive tract organs in different animal groups. The present study foc used on this problem and report our observations on biochemical charac teristics of male-associated polypeptide (MAP) identified in the gonad tissue of bivalve molluscs, Mytilus galloprovincialis, in comparison to those of male-specific carboxylesterase (esterase S) of Drosophila virilis ejaculatory bulbs. We provide evidences for the immunochemical similarity of Mytilus MAP and Drosophila esterase S. We also show tha t MAP is characterized by esterase activity toward both, alpha- and be ta-naphthyl acetates. Using immunofluorescence,we found MAP in the gon ad (mantle) connective tissue, membranes oi follicles and around gonad ducts but nor in sperm cells. Nevertheless, the levels oi MAP express ion depend on presence or absence of ripe spermatozoa in the gonad fol licles. In mature gonads before spawning, MAP is expressed at high lev el, while in the spent gonads only traces of this polypeptide could be detected. Using Western immunoblot, MAP was not observed in spermatoz oa obtained by biopsy of gonad follicles. In contrast, we found this p rotein in spawned sperm cells. Thus, we suggest that spawning may be r equired to establish the trafficking mechanisms that control whether M AP is retained or excreted by the gonad. Taken together, the results i ndicate that MAP of M. galloprovincialis is structurally and functiona lly related to esterase S of D. virilis ejaculatory bulbs. (C) 1997 El sevier Science Inc.