title: 35S a and b RNA subunits of avian RNA tumor virus strains cloned and passaged in chick and duck cells.
abstract: The RNA of transforming and nontransforming avian RNA tumor viruses was heat denatured and examined for its 35S subunit composition by polyacrylamide gel electrophoresis (gel slicing and/or autoradiography). The RNA of virus strains capable of transforming chick embryo fibroblasts in vitro always contained a subunits: the RNA of Pr-RSV of subgroups A, B or C was composed only of a subunits, even after prolonged passage in chick cells, whereas the RNA of SR-RSV-A, SR-RSV-B, SR-RSV-D(H) and B77 also contained b subunits in varying amounts, even when examined as early as possible (8-10 days) after cloning. The b subunit content did not correlate with length of time after cloning. Nontransforming viruses such as RAV-2 and nontransforming derivatives of transforming viruses such as NT-SR-RSV-A, SR-RSV-B AV-3, NC-SRV-D(H), NC-SRV-D(H)(U4), NC-B77-42 and NC-B77-43 contained only b subunits. When B77 virus grown in chick cells was passaged in duck embryo fibroblasts, the ratio of a/b subunits in its RNA did not change markedly. However, when it was cloned in duck embryo fibroblasts, the transformed clones produced virus that contained almost exclusively b subunits. On transfer to chick cells, a subunits once again appeared, and the a/b subunit ratio was soon similar to that of the original B77. B77 virus produced by cloned, transformed duck embryo fibroblasts was found to contain a large excess of nontransforming virus particles.
mesh_terms: D001355:Alpharetrovirus / Q000032:analysis / Q000378:metabolism*; D001358:Avian Sarcoma Viruses / Q000032:analysis; D002460:Cell Line; D002471:Cell Transformation, Neoplastic; D003673:Defective Viruses / Q000032:analysis; D008970:Molecular Weight; D012367:RNA, Viral / Q000032:analysis / Q000302:isolation & purification / Q000378:metabolism*
chemical_list: D012367:RNA, Viral