The origin of 7 S RNA in virions of avian sarcoma viruses.

Duck and chick embryo fibroblasts were labeled with ³²PO₄^3? and cellular 7S RNA was purified. Ribonuclease T₁ digests were prepared and the resulting oligonucleotides were fractionated by two-dimensional electrophoresis. Duck 7 S RNA lacked one large oligonucleotide present in chicken 7 S RNA, thus establishing that the two species contain 7 S RNAs of different sequence. The Prague C strain of Rous sarcoma virus was grown in each type of host and the 7 S RNA found in progeny virus was examined. It was found to be identical to that of the host which produced the virus.