Relative biological efficiency for the induction of various gene mutationsin normal and enriched with B-10 Tradescantia cells by neutrons from Cf-252 source

The effectiveness of neutrons from a Californium-252 source in the inductio n of various abnormalities in the Tradescantia clone 4430 stamen hair cells (Trad-SH assay) were studied. A special attention was paid to check whethe r any enhancement in effects is visible in the cells enriched with boron io ns. Inflorescences. normal or pretreated with chemicals containing boron, w ere irradiated in the air with neutrons from a Cf-252 source at KAERI, Taej on, Korea. To estimate the relative biological effectiveness (RBE) of the b eam under the study, numbers of Tradescantia inflorescence without chemical pretreatment were irradiated with various doses of X-rays. The ranges of r adiation doses used for neutrons were 0-1.0 Cy and for X-rays 0-0.5 Gy. Fol lowing the culturing according to standard procedures screening of gene and lethal mutations in somatic cells of stamen hairs was done in the extended period, between days 7 and 19 after exposures. Maximal RBE values for the induction of pink, colorless and lethal mutations were evaluated from compa rison of the slopes in linear parts of the dose response curves obtained af ter irradiation with X-rays and californium source. The RBEmax value or the induction of gene mutation was estimated as 7.2 comparing the value 5.6 in the studies reported earlier. The comparison of dose-response curves and i ts alteration, due to changes in the cells and plants environment during an d after irradiation, explains the observed differences. Inflorescence pretr eated with borax responded to neutrons differently depending on the biologi cal end points. Although: for the induction of pink mutations no significan t difference was observed. though, in the case of cell lethality, pretreate d with boron ion plants have shoved a statistically significant increase of the RBE value from 5.5 to 34.7, and in the case of colorless mutations fro m 1.6 to 5.6. (C) 2001 Elsevier Science B.V. All rights reserved.