Putative polypeptide transfer from male to female Schistosoma mansoni

Mature males and females, and unisexual females of Schistosoma mansoni were incubated in medium containing [14C]leucine. By use of polyacrylamide gel electrophoresis and fluorography no differences were detected in their ability to synthesize polypeptides. Male worms thus labelled were paired for various periods with unlabelled mature or unisexual females both in vitro and by surgical implantation into hamsters. Female worms paired in vitro had two controls: an accompanying female that did not pair and an additional female placed in the conditioned medium after removal of the other worms. After separation and washing, only small amounts of label were found in females by liquid scintillation counting despite the release by males of substantial amounts of label into the medium. No label was detected in fluorograms of polyacrylamide electrophoresis gels of re-paired females after 7 days' exposure to X-ray film, but a faint pattern of normal polypeptides above 50 kDa did develop after 6 weeks. In light microscope autoradiographs a low grain count was found over sections of unlabelled females paired with labelled males but this was no greater than that over females incubated in medium that had formerly held males. We have been unable to detect any polypeptide reported to be synthesized exclusively by male worms and transferred in large amounts to females. Although female worms did take up small amounts of male-derived metabolic products, the transfer of a specific polypeptide of 66 kDa in significant quantities did not take place under the conditions investigated.