IN-VIVO LABELING OF SCHISTOSOMA-JAPONICUM CERCARIAE WITH S-35

A technique was developed for in vivo labeling of adult Schistosoma ja ponicum worms using S-35 bound to methionine and cysteine. The isotope was applied in an in vivo labeling system in which Oncomelania hupens is snails harboring a patent S. japonicum were in individually exposed to the label, Following exposure to cercariae, mice were perfused aft er 6 wk. For autoradiography and fluorography, the worms were mounted on cardboard. covered with x-ray films, and exposed for 5 wk. With bot h techniques, images of bath malt and female worms were obtained in th e 1- and 2-mu Ci groups, but not in the 0.5-mu Ci group. Fluorography proved more sensitive than autoradiography. Snail survival, labeled ce rcariae, and worm establishment were not affected by the radiolabeling . S-35 was thus found useful for radiolabeling adult S. japonicum worm s.