title: Synergistic effects of N-ethyl-N-nitrosourea (an alkylating agent with a low Swain-Scott substrate constant) and X-rays in the stamen hairs of Tradescantia clone BNL 4430.
abstract: The mutagenic interaction between N-ethyl-N-nitrosourea (ENU) and X-rays was tested in the stamen hairs of Tradescantia clone BNL 4430, a blue/pink heterozygote. ENU, a monofunctional alkylating agent with a low Swain-Scott substrate constant (s) of 0.26, exhibited a strong cytotoxicity. ENU-induced somatic pink mutation frequency per 10(4) hair-cell divisions increased with increasing ENU dose, with a slope of 1.243 on a log-log graph, the slope value being similar to that for X-ray-induced mutation frequency. Three out of five combined treatments with ENU and X-rays produced mutation frequencies significantly higher than those expected from the additive effects of the two mutagens. Clear synergistic effects were detected when relatively higher X-ray doses were applied, resembling those confirmed earlier between methyl methanesulfonate (MMS) and X-rays, although the s value for ENU is very much smaller than that (0.88) for MMS. It is therefore concluded that mutagenic interactions between alkylating agents and X-rays do not have any clear relationship with the s values.
authors.affiliation: Department of Regulation Biology, Faculty of Science, Saitama University, Urawa, Japan.
authors.forename: N
authors.initials: N
authors.lastname: Shima
authors.forename: S
authors.initials: S
authors.lastname: Ichikawa
mesh_terms: D004307:Dose-Response Relationship, Radiation; D005038:Ethylnitrosourea / Q000633:toxicity*; D009153:Mutagens / Q000633:toxicity*; D010944:Plants / Q000187:drug effects* / Q000528:radiation effects*; D014965:X-Rays
chemical_list: D009153:Mutagens; D005038:Ethylnitrosourea