Induction of in vivo somatic mutations by low dose radiation in mice -threshold and dose rate effects-.

采用体内体细胞突变法（PH-HTF1）研究了低剂量辐射对小鼠的遗传效应。剂量率效应也用同样的方法进行了试验。10R X射线诱导体内体细胞突变：PT雌性与HT雄性交配，然后在妊娠10-1/2天给予10R X射线（55-62R/min）。出生6周后处死F1小鼠（a/a,b/+,pc^<ch>/+,d/+,pa/+,pe/+,in/+），在非豚鼠（黑色）背景上检测色斑。10R暴露后，746F1后代中发现30个斑点（0.04），而750个未暴露对照中发现22个斑点。在0和130 R.2之间没有明显偏离线性剂量反应关系。慢性照射诱导体内体细胞突变：在同一时间段内以不同剂量率（55 ~ 62r /min、1r /min、0.5R/min）照射110 R的X射线，0.1R/min照射32.5R。每个F1的突变体数分别为26/218（0.119）、23/116（0.198）、25/161（0.155）和8/59（0.136）。靶细胞存活数和每个位点每R的突变率：根据毛总数和突变毛的比值估计靶细胞数。估计靶细胞数分别为530、1211、1853和3500。结果表明，在55 ~ 62 R/min 1.0R/min、0.5R/min和0.1R/min剂量下，每个R位点的突变率分别为1.9x10^<-7>、1.6x10^<-7>、0.8x10^<-m>和1.1x10^<-7>，与精原细胞特异性位点突变的结果一致。阈值/剂量率效应/人类遗传风险

Genetic effects of low dose radiation were examined with the use of in vivo somatic mutation method (PH-HTF1)in mice.Dose rate effects were also tested with the same method.1.Induction of in vivo somatic mutations with 10R of X rays:PT female was mated with HT males, and then 10R of X rays(55-62R/min)was given on the 10-1/2 the day of gestation.F1 mice (a/a,b/+,pc^<ch>/++,d/+,pa/+,pe/+,in/+)were sacrificed 6 weeks after birth,and colored spots were examined on the non-agouti(black)background.30 spots were found in 746F1 offspring(0.04)after 10R exposure,whereas 22spots were found in 750 unexposed controls. There is no significant diviation from linear dose response relationship between 0 and 130 R.2.Induction of in vivo somatic mutations by chronic exposure:110 R of X rays were given at different dose rate,55-62R/min,1 R/min,0.5R/min in the same time schedule.32.5R was also given at 0.1R/min.Numbers of mutants per F1 were 26/218(0.119),23/116(0.198),25/161 (0.155),and 8/59(0.136),respectively.3.Numbers of survived target cells and mutation rate per locus per R:Numbers of target cells were estimated from the ratio of total numbers of hair and mutant hairs.Estimated numbers of target cells were 530,1211,1853,and 3500,respectively.Consequently,mutation rate per locus per R was 1.9x10^<-7>,1.6x10^<-7>,0.8x10^<-m>,and 1.1x10^<-7>at dose rate of 55-62 R/min 1.0R/min,0.5R/min,and 0.1R/min,respectively,The results were compatible with those by specific locus mutations for spermatogonia.Threshold/Dose rate effect/Human genetic risk