SCHISTOSOMA-MANSONI - CHANGES IN THE ALBUMIN GLAND OF BIOMPHALARIA-GLABRATA SNAILS SELECTED FOR NONSUSCEPTIBILITY TO THE PARASITE

The LAC-line strain of the snail Biomphalaria glabrata has very low su sceptibility to the parasite Schistosoma mansoni and a very low reprod uctive potential. Upon examination of the reproductive tract of these snails, light and electron microscopy revealed obvious abnormalities i n the albumen gland. Secretory cells that are normally cuboidal in sus ceptible NMRI (F-0) snails were squamous in LAC-line snails. These LAC -line cells contained small secretory granules and negligible rough en doplasmic reticulum and Golgi, compared to large granules and an exten sive array of both organelles in F-0 albumen gland cells. Comparative analyses of soluble protein extracts of F-0 and LAC-line albumen gland s showed several qualitative differences. Among the most prominent was an 18-kDa protein in F-0 snails that was remarkably reduced in the so luble protein extracts of LAC-line snails. Also, metabolic incorporati on of [S-35]-methionine was impaired in LAC-line albumen glands. Wheth er these albumen gland changes are caused by decreased susceptibility to parasitism is yet to determined.