A FEMALE-SPECIFIC CDNA SEQUENCE OF SCHISTOSOMA-MANSONI ENCODING A MUCIN-LIKE PROTEIN THAT IS EXPRESSED IN THE EPITHELIAL-CELLS OF THE REPRODUCTIVE DUCT

Seven cDNA clones of Schistosoma mansoni containing the C-terminal part of the deduced sequence of a mucin-like protein have been identified. The protein contains 28 % threonines, 20 % serines, and has a pi of 3.4. On Northern blots of RNA of adult worms, the cDNA clones detect 2 transcripts of 1.65 and 4.2 kb which are expressed only in female worms. The tissue of gene expression, as revealed by in situ hybridization, is the epithelium surrounding the female reproduction duct proximal to its entrance into the ootype. Accumulation of N-glycosylation sires suggests that the protein, like other mucins, might form a protective layer, coating the lining of the duct. Regarding its acidic pi, we hypothesize a role in preventing premature egg-shell formation. This is the first female-specifically transcribed sequence, hitherto known in S. mansoni that is not expressed in the vitellaria.