title: Virus-specific DNA in the cytoplasm of avian sarcoma virus-infected cells is a precursor to covalently closed circular viral DNA in the nucleus.
abstract: Three principal forms of viral DNA have been identified in cells infected with avian sarcoma virus: (i) a linear duplex molecule synthesized in the cytoplasm, (ii) a covalently closed circular molecule found in the nucleus, and (iii) proviral DNA covalently linked to high-molecular-weight cell DNA. To define precursor product relationships among these forms of viral DNA, we performed pulsechase experiments using 5-bromodeoxyuridine to label by density the linear species of viral DNA in the cytoplasm during the first 4 h after infection. After a 4-to 8-h chase with thymidine, a portion of the density-labeled viral DNA was transported to the nucleus and converted to a covalently closed circular form. We conclude that linear viral DNA, synthesized in the cytoplasm, is the precursor to closed circular DNA observed in the nucleus.
mesh_terms: D000818:Animals; D001358:Avian Sarcoma Viruses / Q000378:metabolism*; D001973:Bromodeoxyuridine; D002460:Cell Line; D002467:Cell Nucleus / Q000378:metabolism; D003593:Cytoplasm / Q000378:metabolism; D004270:DNA, Circular / Q000096:biosynthesis; D004279:DNA, Viral / Q000096:biosynthesis*; D009694:Nucleic Acid Precursors / Q000096:biosynthesis*; D011784:Quail
chemical_list: D004270:DNA, Circular; D004279:DNA, Viral; D009694:Nucleic Acid Precursors; D001973:Bromodeoxyuridine