Identification of schistosome hybrids and larval parasites using rRNA probes

Abstract

Observations have been made on the ribosomal RNA (rRNA) gene units of hybrid progeny produced by experimental crosses of S. haematobium × S. mattheei, S. mattheei × S. bovis and S. haematobium × S. intercalatum. Hybridisation of DNA probe pSM 889 to restriction endonuclease digested DNA extracted from adult worms showed that each parental form could be differentiated by differences in the rRNA gene unit. In each experimental cross the F1 hybrid generation produced a composite major banding pattern of the two parental species. No differences associated with the stage of development were detected in the major bands of hybridisation when DNA extracted from various life-cycle stages of S. mansoni and S. margrebowiei was digested with EcoR1 and hybridised with probe pSM 889. Prepatent infections of S. mansoni in Biomphalaria glabrata were detected 16 days post-infection utilising probe pSM 389 and dot blot analysis. Small numbers of intact cercariae dotted onto nitrocellulose were detected using probe pSM 389, 10 cercariae being the minimum number required for accurate determination.