ASSOCIATION OF ROUS-SARCOMA VIRUS-DNA WITH XENOPUS-LAEVIS SPERMATOZOAAND ITS TRANSFER TO OVA THROUGH FERTILIZATION

Mature Xenopus laevis spermatozoa are capable of binding plasmid pAPrC carrying the complete Rous sarcoma virus (RSV) DNA. Each sperm cell a ssociates, on an average, with 70-160 molecules of the plasmid DNA in a DNase resistant form, if the spermatozoa were exposed to the DNA at a concentration of 1.0-1.4 mu g/10(7) sperm cells. Fertilization with pAPrC-treated spermatozoa induced developmental malformations in 25-30 % of embryos. Immunohistochemical analysis of tissue sections from def ective animals revealed aberrations in myotomal structures, and increa sed expression of pp60(src) protein in myoblasts, neuronal tube, and e pidermis. The presence of characteristic v-src and RSV-long terminal r epeat (LTR) sequences in X. laevis DNA was detected by PCR analysis. E mbryonic RNA hybridized with a src-specific and an RSV-LTR specific pr obes indicating expression of the viral DNA. Plasmid DNAs without the v-src gene (pATV9) or completely free of any RSV sequences (pBR322) di d not induce any changes in embryonic development. Our results provide evidence that the pBR322-cloned DNA form of the RSV genome associates with frog sperm cells in a DNase-resistant manner suggesting internal ization and may be subsequently carried into eggs during the process o f artificial fertilization. Correlation between the defective morphoge nesis of X. laevis and increased expression of the src gene as well as an interference of RSV DNA with the developmental programs of frog em bryos are discussed. (C) 1996 Wiley-Liss, Inc.