title: Double-strand breaks from 125I incorporated in the DNA and cell death.
abstract: Track structure calculations of the local energy deposition by electrons emitted during the decay of 125I are used to demonstrate that the range of high energy deposition is small (< 10 nm) and restricted to the DNA and its immediate environment. An experiment in which 125I is incorporated into the DNA of synchronized CHO cells during a pulse and decays are allowed to accumulate a given time after the incorporation is described. Here it is shown that damage from 125I decays in newly replicated DNA (cells frozen for decay accumulation within 1 h after labelling) are relatively non-toxic whereas decays in mature DNA (cells frozen 5 h after labelling) are highly lethal. It is suggested that during DNA maturation the labelled DNA becomes associated with (or reorganized into) a radiosensitive nuclear structure and that damage to this structure is the primary cause of radiation-induced cell death.
authors.affiliation: Concordia University, Montreal, Canada.
authors.forename: D E
authors.initials: DE
authors.lastname: Charlton
authors.forename: K G
authors.initials: KG
authors.lastname: Hofer
authors.forename: N
authors.initials: N
authors.lastname: Vanloon
authors.forename: M H
authors.initials: MH
authors.lastname: Schneiderman
mesh_terms: D000818:Animals; D016466:CHO Cells; D016923:Cell Death / Q000528:radiation effects*; D006224:Cricetinae; D004247:DNA / Q000528:radiation effects*; D004249:DNA Damage; D007457:Iodine Radioisotopes
chemical_list: D007457:Iodine Radioisotopes; D004247:DNA