Effects of polychlorinated biphenyls (PCBs) on root meristem cells of common onion (Allium cepa L.) and on early life stages of zebrafish (Danio rerio)
2008
Quilang, J.P. | de Guzman, M.C. | Catalan, M.H.dH., Philippines Univ. Diliman, Diliman, Quezon City (Philippines). Inst. of Biology | Rubio, R.O., Philippines Univ. Diliman, Diliman, Quezon City (Philippines). National Inst. for Science and Mathematics Education Development | Jacinto, S.D., Philippines Univ. Diliman, Diliman Quezon City (Philippines). Inst. of Biology | Santiago, E.C., Philippines Univ. Diliman, Diliman, Quezon City (Philippines). National Inst. for Science and Mathematics Education Development | Cao, E.P., Philippines Univ. Diliman, Diliman, Quezon City (Philippines). Inst. of Biology
Polychlorinated biphenyls (PCBs) are chemical mixtures that are common environmental pollutants and considered potential carcinogens. In this study, the common onion, Allium cepa, was used to determine the cytotoxicity and genotoxicity of a mixture of PCBs at three concentrations, namely, 10 nM, 100 nM and 1000 nM. Distilled deionized water and 0.2% dimethylsulfoxide (DMSO) were used as negative controls. Cytotoxicity was observed at the three concentrations tested as shown by a significant reduction in average mitotic indices. Chromosomal aberrations were also observed, which is suggestive of the genotoxicity of these pollutants. The effects of PCBs on the early life stages of zebrafish, Danio rerio, were also investigated. The three levels of PCBs were tested including the embryo medium, 0.2% DMSOand 2% ethanol that served as controls. Embryos at 6-8 hours postfertilization were exposed to the different treatments and were observed everyday for 5 days. Results showed a significant decrease in the mean number of melanocytes and average length at 5 days postfertilization, a delay in hatching of embryos and a significant increase in average percent of fish with deformities for the 1000 nM PCB concentration. This study demonstrates that the Allium test is a simple and reliable method to assess cytotoxicity and genotoxicity of PCBs. Exposure of zebrafish embryos to high concentrations of PCBs also delays growth and hatching rates and causes teratogenic effects. These results may have implications on the health of humans and other organisms at risk to PCB exposures as these chemicals are known to bioaccumulate.
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