TANDEMLY REPEATED GENOMIC SEQUENCE DEMONSTRATES INTER-STRAIN AND INTRA-STRAIN GENETIC-VARIATION IN SCHISTOSOMA-JAPONICUM

Genetic variability within and among four geographical strains of Schi stosoma japonicum was examined using a novel repetitive element. The e lement, termed Sjrh1.0, was isolated from genomic DNA of a Philippine strain of S. japonicum using a combination of restriction fragment PCR and band-stab PCR. Sjrh1.0 is a tandemly repeated element, the sequen ce of which appears to be species-specific, in that it hybridized to D NA from S. japonicum but not to DNA from S. mansoni. Its sequence does not match previously deposited sequences in GenBank. When employed as a probe in Southern hybridization analysis, radiolabelled Sjrh1.0 rev ealed sex-specific and strain-specific differences in genomic DNA of i ndividual worms. We also found individual genetic variation within geo graphical isolates of the Asian schistosome.