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

  Objective   To investigate the effects of holmiumions on genetic damage to root-tip cells of vicia faba and its molecular mechanism.

  Methods   Crystal of nitrate, made by reaction of holmium trioxide and nitric acid, was dissolved in distilled water, then diluted into gradient 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 calculated under microscope and the DNA damage was tested by single cell gel electrophoresis(SCGE).

  Results   The frequencies of micronuclei or chromosomal aberration were induced to increase, and certain dose-dependent responses were showed(r_FMN=0.962, P < 0.01;r_CAF=0.960, P < 0.05).The DNA damage was also caused by holmium ions.The average head diameter decreased gradually, and the average tail length increased with the rise of dosage compared with control.Meanwhile, the percentage of tailed cells and ratio of damaged DNA increased with the rise of concentrations.

  Conclusion   Holmiumions had certain genotoxicity to root-tip cells of vicia faba.The molecular mechanism for chromosomal aberration and micronuclei induced by holmiumions was most probably DNA breakage to root-tip cells of vicia faba.