镍对蚕豆根尖细胞的遗传毒性效应

Genotoxic Effects of Nickel on Root Tip Cells of Vicia faba L.

采用蚕豆根尖细胞微核试验,研究了不同浓度硝酸镍(5￣5000μmol·L-1)对蚕豆根尖生长、细胞有丝分裂指数(MI)、微核率以及染色体畸变的影响,以此评价镍的遗传毒性和蚕豆根尖微核技术应用于镍污染检测的可行性。结果表明,5μmol·L-1镍显著促进根的生长,提高有丝分裂指数,对微核形成和染色体畸变无明显影响。在10￣5000μmol·L-1镍浓度范围,蚕豆根的生长受阻,有丝分裂指数下降,表现出明显的剂量-效应关系;微核率和染色体畸变率先升高,且呈明显的剂量-效应关系,分别于100μmol·L-1和50μmol·L-1达到最大值;随着镍浓度的增加,两者均下降,但仍显著高于对照。镍引起的染色体畸变以染色体断片和落后染色体为主。这些结果表明,镍能诱导蚕豆根尖细胞微核的产生和染色体畸变,具有一定的遗传毒性;同时表明,在5￣500μmol·L-1浓度范围内,蚕豆根尖微核检测体系可应用于镍污染的监测。

Nickel is one of the most toxic environmental pollutants affecting genetically the various organisms. In order to evaluate the genotoxicity of nickel and the feasibility of nickel pollution detection by Viciafaba-micronucleus test, we examined the growth, mitotic index, rate of micronuclei formation and chromosome aberrations in root tip cells of Viciafaba L. after exposure to different concentrations of nickel nitrate ranging from 5 to 5 000 μmol·L^-1. The results showed that nickel enhanced significantly the growth of root tip cells and mitotic index, but had no evident effects on the formation of micronuclei and chromosome aberrations at low concentration of 5 μmol·L^-1. However, higher concentrations of 10-5 000 μmol·L^-1 nickel decreased the growth of root tip ceils and mitotic index with significant dose-effect relationship. The rate of micronuclei and chromosome aberrations was increased dose-dependently, reaching the maximum values at 100 μmol·L^-1 and 50 μmol·L^-1, respectively, followed by a drop with the increase of nickel concentrations, however, both higher than those of the control. Fragmental and lagging chromosomes were predominant in chromosome aberrations caused by nickel. These results indicate that nickel exerts genotoxicity to root tip cells of Viciafaba L. to a certain degree, as shown by micronucleus formation and chromosome aberrations. The results also indicate that Viciafaba-micronucleus test is feasible for detection of nickel pollution in environment at certain concentrations ranging from 5 to 500 μmol·L^-1.