稀土钬离子对蚕豆根尖细胞的遗传损伤

目的　探讨稀土钬离子对蚕豆根尖细胞的遗传毒性及其分子机制。方法　运用氧化钬与稀硝酸反应制备硝酸钬结晶 ,配制硝酸钬梯度溶液 ,对蚕豆根尖染毒 6h ,修复 2 4h后检测根尖细胞的微核率 (FMN‰ )、染色体畸变率 (CAF‰ )及DNA损伤。结果　钬离子溶液诱导了蚕豆根尖细胞FMN‰、CAF‰升高 ,并呈现一定的剂量 -效应关系 (rFMN=0 96 2 ,P <0 0 1;rCAF=0 96 0 ,P <0 0 5 ) ;钬离子诱导了蚕豆根尖细胞DNA损伤 ,表现为随着剂量的递增 ,彗星头长缩短 ,尾长、拖尾率和DNA损伤率增加。结论　钬离子对蚕豆根尖细胞具有一定的遗传损伤作用 ;钬离子诱导蚕豆根尖细胞染色体畸变和微核产生的分子机制主要为DNA断裂作用。

Genetic damage to root-tip cells of vicia faba induced by holmium ions of rare earths

Objective To investigate the effects of holmium ions on g enetic damage to root-tip cells of vicia faba and its molecular mechanism.Methods Crystal of nitrate,made by reaction of holmium tr ioxide and nitric acid,was dissolved in distilled water,then diluted into gradie nt solutions.Soaked in such holmium nitrate solutions for 6 hours,root tips of vicia faba were then recovered and cultivated for 24 hours,respectively.The frequencies of micronuclei and chromosomal aberration in root-tip cells were cal culated under microscope and the DNA damage was tested by single cell gel electr ophoresis (SCGE).Results The frequencies of micronuclei or chromosomal abe rration were induced to increase,and certain dose-dependent responses were showe d (r FMN=0.962,P<0.01;r CAF=0.960,P<0.05).The D NA damage was also caused by holmium ions.The average head diameter decreased gr adually,and the average tail length increased with the rise of dosage compar ed with control.Meanwhile,the percentage of tailed cells and ratio of damaged DN A increased with the rise of concentrations.Conclusion Holmium ions had certain genotoxicity to root- tip cells of vicia faba.The molecular mechanism for chromosomal aberration and micronuclei induced by holmium ions was most probably DNA breakage to root-tip c ells of vicia faba.