title: Single-stranded DNA from oncornavirus-infected cells enriched in virus-specific DNA sequences.
abstract: We previously found that a minor fraction of single-stranded DNA (ss-DNA) isolated from native nuclear DNA of normal chicken embryonic cells and cells of other species hybridized with bulk nuclear DNA or cellular RNA in great excess. At least one-third of ss-DNA belonging to the nonrepetitious part of the cell genome could be hybridized to homologous RNAs. In the present work, similar results were obtained with ss-DNA from cells of chickens infected by avian myeloblastosis virus (AMV). To investigate whether this enrichment of ss-DNA in transcribed DNA sequences involves provirus DNA, radioactive AMV RNA and cDNA copies of AMV RNA were used. Most of the 70S AMV RNA hybridized much faster to ss-DNA from productively infected leukemic cells than to bulk DNA. cDNA, either double-stranded or single-stranded, made in the presence of actinomycin D hybridized to total nuclear DNA with similar kinetics. In contrast, about half of the double-stranded cDNA molecules hybridized 40-50 times faster to ss-DNA than to total DNA, indicating that only one of the provirus DNA strands seems to be present in ss-DNA. This was confirmed by the fact that relatively insignificant amounts of the ss-cDNA molecules made in the presence of actinomycin D could be annealed to ss-DNA as compared with bulk DNA. These results indicate that actively transcribed DNA sequences can be selectively distributed in the ss-DNA fraction, probably because of single strand breaks in the vicinity of transcription sites.
mesh_terms: D000818:Animals; D001354:Avian Leukosis Virus / Q000378:metabolism*; D009189:Avian Myeloblastosis Virus / Q000378:metabolism*; D002645:Chickens; D004277:DNA, Single-Stranded / Q000096:biosynthesis / Q000302:isolation & purification; D004279:DNA, Viral / Q000096:biosynthesis / Q000302:isolation & purification; D007700:Kinetics; D007942:Leukemia, Experimental / Q000097:blood; D009693:Nucleic Acid Hybridization; D009695:Nucleic Acid Renaturation
chemical_list: D004277:DNA, Single-Stranded; D004279:DNA, Viral