title: The origin of yolk-DNA in Xenopus laevis.
abstract: Xenopus laevis serum and plasma was found to contain an average of 25 microgram DNA/ml. Isolated X. laevis oocytes incubated in medium containing 25 microgram DNA/ml labeled with either 125I, 32P or 14C and from three different sources (bovine, E. coli and X. laevis), incorporated the label at an average rate of 0.11 ng.mm-2.hr-1. Sucrose gradient fractionation of oocytes revealed that 40-75% of the acid-precipitable label incorporated was associated with the yolk platelets. Additional incubations of oocytes in unlabeled medium demonstrated that the DNA incorporated into the yolk platelets was undergoing turnover; only 20% of the yolk-associated DNA was still present after a one-week incubation. Our data suggest that yolk-DNA arises by the adventitious uptake of DNA present in the maternal serum by vitellogenic oocytes.
mesh_terms: D000818:Animals; D002417:Cattle; D002499:Centrifugation, Density Gradient; D004247:DNA / Q000097:blood* / Q000302:isolation & purification / Q000378:metabolism*; D004269:DNA, Bacterial / Q000378:metabolism; D004926:Escherichia coli; D005260:Female; D008099:Liver / Q000378:metabolism; D009865:Oocytes / Q000378:metabolism*; D010063:Ovum / Q000378:metabolism*; D014981:Xenopus / Q000097:blood*; D015017:Yolk Sac / Q000378:metabolism*
chemical_list: D004269:DNA, Bacterial; D004247:DNA