HOST-RELATED DNA-SEQUENCES ARE LOCALIZED IN THE BODY OF SCHISTOSOME ADULTS

The localization of host (mouse)-related DNA sequences in the adults a nd cercariae of Schistosoma japonicum and S. mansoni was examined by i n situ hybridization using P-32-labelled probes. The hybridization sig nals to the sequences of the mouse type C and type A retroviruses were clearly observed in the subtegumental layer and inner tissues of S. j aponicum adults. In contrast, it was hard to find any signals to these sequences in S. mansoni adults. Distinct signals to the env-specific region of the mouse ecotropic type C retrovirus were observed in the s ubtegumental layer and inner tissues of S. mansoni adults. No signal t o the sequence of the mouse type B retrovirus was found on the section s of either schistosome adult. The signals to the sequence of the geno mic clone SmM51 derived from male S. mansoni were found in the tissues of both the schistosome adults. The signals to the sequences of the m ouse type A and env-specific region of ecotropic type C retroviruses w ere not seen in the cercariae of each species, whereas the signals to the sequence of SmM51 were detected in S. mansoni cercariae. These obs ervations suggest that host-related DNA sequences might be incorporate d unequally into the schistosome genome during development in the fina l host.