title: [Metabolic and structural properties of extrachromosomal DNA in mammalian cells].
abstract: Discrete bands of free DNAs of approximately 25 kbp were detected in human cell cultures. According to electrophoretic shifts induced by single and double strand breaks, they from topological isoforms (supercoiled, open, and linear). Long-term labeling (24 h) of growing and quiescent cultured cells by [3H]thymidine indicates differences of free versus chromosomal DNAs including (i) significantly lower specific radioactivity in growing cells, (ii) higher specific radioactivity in quiescent cells, and (iii) resistance to fluorodeoxyuridine labeling. During apoptosis of cultured Namalwa cells, heterogeneous fragments are formed which differ from free DNAs. Crosslinking of nascent RNA with DNA template by 8-methoxypsoralen indicated slight transcriptional activity of free DNAs.
authors.forename: O I
authors.initials: OI
authors.lastname: Serdiuk
authors.forename: T I
authors.initials: TI
authors.lastname: Sukhova
authors.forename: R P
authors.initials: RP
authors.lastname: Alekhina
authors.forename: V P
authors.initials: VP
authors.lastname: Shelepov
authors.forename: S L
authors.initials: SL
authors.lastname: Arsenin
authors.forename: V L
authors.initials: VL
authors.lastname: Moiseev
authors.forename: A V
authors.initials: AV
authors.lastname: Likhtenshteĭn
mesh_terms: D017209:Apoptosis; D002478:Cells, Cultured; D004247:DNA / Q000737:chemistry* / Q000378:metabolism; D004249:DNA Damage; D006801:Humans; D009690:Nucleic Acid Conformation; D014158:Transcription, Genetic
chemical_list: D004247:DNA