Desai Somshekhar R, Verlecar Xivanand N, Goswami Usha
Biological Oceanography, National Institute of Oceanography, Dona Paula, 403 004 Goa, India.
Ecotoxicology. 2006 May;15(4):359-63. doi: 10.1007/s10646-006-0076-2. Epub 2006 May 4.
Genotoxic effects of cadmium on phytoplankton Chaetoceros tenuissimus have been evaluated using DNA damage by Comet assay. Cadmium concentrations ranging from 2.4 to 10 mg/l were used to evaluate the effects. Results showed that as the concentration of Cd increased growth of the diatom decreased. Alkaline single-cell gel electrophoresis (Comet assay) method, which is highly sensitive in detection of DNA damage in eukaryotic cells, was used to observe genomic changes in marine diatom cells. DNA damage was measured as percent number of comets and normal cells. 65% cells were found to be damaged at 10 mg/l concentration of Cd as compared to 23% in 2.4 mg/l and only 5% in controls. More than 50% apoptotic cells were observed on 8th day at 10 mg/l and 12th day at 7.5 mg/l concentrations. At lower Cd concentrations (4.5 mg/l and below) the damage was below 30% till the last day. This suggested that higher Cd levels have early damaging effects on cell nuclear material and that % injury increases with advancement of exposure period. One advantage of use of C. tenuissimus is the ease with which it can be cultured in a defined medium. C. tenuissimus diatom can be used as an in vivo model for ecogenotoxicity assessment using the Comet assay.
已通过彗星试验检测DNA损伤，评估了镉对浮游植物细弱角毛藻的遗传毒性作用。使用2.4至10毫克/升的镉浓度来评估其影响。结果表明，随着镉浓度的增加，硅藻的生长减少。碱性单细胞凝胶电泳（彗星试验）方法在检测真核细胞DNA损伤方面高度敏感，用于观察海洋硅藻细胞的基因组变化。DNA损伤以彗星细胞和正常细胞的百分比来衡量。与2.4毫克/升时的23%以及对照组的仅5%相比，在镉浓度为10毫克/升时发现65%的细胞受损。在镉浓度为10毫克/升时，第8天观察到超过50%的凋亡细胞；在镉浓度为7.5毫克/升时，第12天观察到超过50%的凋亡细胞。在较低的镉浓度（4.5毫克/升及以下）下直到最后一天损伤都低于30%。这表明较高的镉水平对细胞核物质有早期损伤作用，且损伤百分比随着暴露时间的延长而增加。使用细弱角毛藻的一个优点是它可以在特定培养基中轻松培养。细弱角毛藻硅藻可以用作使用彗星试验进行生态遗传毒性评估的体内模型。
