Association of rous sarcoma virus DNA with Xenopus laevis spermatozoa and 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 associates, 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 micrograms/10(7) sperm cells. Fertilization with pAPrC-treated spermatozoa induced developmental malformations in 25-30% of embryos. Immunohistochemical analysis of tissue sections from defective animals revealed aberrations in myotomal structures, and increased expression of pp60src protein in myoblasts, neuronal tube, and epidermis. The presence of characteristic v-src and RSV-long terminal repeat (LTR) sequences in X. laevis DNA was detected by PCR analysis. Embryonic RNA hybridized with a src-specific and an RSV-LTR specific probes indicating expression of the viral DNA. Plasmid DNAs without the v-src gene (pATV9) or completely free of any RSV sequences (pBR322) did 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 internalization and may be subsequently carried into eggs during the process of artificial fertilization. Correlation between the defective morphogenesis of X. laevis and increased expression of the src gene as well as an interference of RSV DNA with the developmental programs of frog embryos are discussed.
Habrová
V
V
Department of Physiology and Developmental Biology, Faculty of Science, Charles University, Prague, Czech Republic.
Takác
M
M
Navrátil
J
J
Mácha
J
J
Cesková
N
N
Jonák
J
J
D000818:Animals; D001358:Avian Sarcoma Viruses / Q000235:genetics*; D004279:DNA, Viral / Q000378:metabolism*; D005306:Fertilization; D019084:Fluorescent Antibody Technique, Indirect; D008297:Male; D010063:Ovum; D012367:RNA, Viral / Q000032:analysis; D013094:Spermatozoa / Q000378:metabolism*; D014982:Xenopus laevis / Q000196:embryology / Q000378:metabolism*
D004279:DNA, Viral; D012367:RNA, Viral