title: Negatively supercoiled DNA from plants infected with a single-stranded DNA virus.
abstract: A method for isolating covalently closed circular double-stranded DNA from plants infected with the geminivirus, tomato golden mosaic virus, is described. Ethidium bromide titration showed this DNA to be negatively supercoiled with a superhelical density of -0.062. The presence of S1 nuclease-sensitive secondary structure in the supercoiled DNA was demonstrated by its conversion to the open circular and linear DNA forms on treatment with this enzyme.
mesh_terms: D004270:DNA, Circular / Q000302:isolation & purification*; D004278:DNA, Superhelical / Q000302:isolation & purification*; D004279:DNA, Viral / Q000302:isolation & purification*; D004720:Endonucleases / Q000494:pharmacology; D004996:Ethidium; D009029:Mosaic Viruses / Q000032:analysis*; D009690:Nucleic Acid Conformation; D010944:Plants / Q000382:microbiology*; D015719:Single-Strand Specific DNA and RNA Endonucleases
chemical_list: D004270:DNA, Circular; D004278:DNA, Superhelical; D004279:DNA, Viral; D004720:Endonucleases; D015719:Single-Strand Specific DNA and RNA Endonucleases; D004996:Ethidium