title: Response of X-ray-sensitive CHO mutant cells (xrs-6c) to radiation. II. Relationship between cell survival and the induction of chromosomal damage with low doses of alpha particles.
abstract: The induction of cytotoxicity, chromosomal aberrations, and sister chromatid exchanges (SCEs) was measured in CHO K-1c cells and in isogenic X-ray-sensitive mutant xrs-6c cells that had been irradiated with X rays and alpha particles in isoleucine-deficient alpha-minimal essential medium in G1 phase of the cell cycle. There was a noticeable shoulder region on the survival curve for CHO K-1c cells irradiated with very low doses of alpha particles, whereas this feature was absent for xrs-6c cells with alpha-particle doses as low as 0.5 cGy. Higher frequencies of chromatid-type aberrations were induced in G1-phase xrs-6c cells than in G1-phase CHO K-1c cells by both gamma- and alpha-particle irradiation. Induction of nonlethal chromosomal aberrations was observed following exposure to 2-6 cGy of alpha particles, doses yielding 97-100% cell survival. Irradiation with 0.5 cGy of alpha particles induced SCE; nearly 60% of irradiated cells contained significantly increased levels of SCE. However, only 3% of the nuclei of cells exposed to 0.5 cGy of alpha-particle radiation were actually traversed by an alpha particle. The observation that a large fraction of cells apparently survive exposure to very low doses of alpha-particle radiation with persistent genetic damage manifested by both chromosomal aberrations and SCEs may have important implications for the carcinogenic hazards of high-LET radiation.
authors.affiliation: Laboratory of Radiobiology, Harvard School of Public Health, Boston, Massachusetts 02115.
authors.forename: H
authors.initials: H
authors.lastname: Nagasawa
authors.forename: J B
authors.initials: JB
authors.lastname: Little
authors.forename: W C
authors.initials: WC
authors.lastname: Inkret
authors.forename: S
authors.initials: S
authors.lastname: Carpenter
authors.forename: M R
authors.initials: MR
authors.lastname: Raju
authors.forename: D J
authors.initials: DJ
authors.lastname: Chen
authors.forename: G F
authors.initials: GF
authors.lastname: Strniste
mesh_terms: D000512:Alpha Particles; D000818:Animals; D002453:Cell Cycle / Q000528:radiation effects; D002460:Cell Line; D002470:Cell Survival / Q000528:radiation effects*; D002869:Chromosome Aberrations; D002875:Chromosomes / Q000528:radiation effects*; D004260:DNA Repair; D004307:Dose-Response Relationship, Radiation; D005720:Gamma Rays; D009154:Mutation; D011836:Radiation Tolerance; D012854:Sister Chromatid Exchange / Q000528:radiation effects