| dc.description.abstract | The individual and combined pesticides of terbufos and fenthion were evaluated using human hepatoma cell line HepG2 and zebrafish embryos to specify the genotoxicity mechanism. To analyze the genotoxicity, the neutral comet assay and H2AX phosphorylation (γH2AX) were used and showed that exposed cells caused DNA double strand breaks (DSBs) when mixed with terbufos and/or fenthion. At the level of equimolar concentration (40 µM), the pesticide combination showed almost no toxicity, genotoxicity, and effects on homologous recombination (HR) activity. Within HepG2 cells, cells exposed to the individual and combined treatment showed decreased expression of Xrcc2, which is an HR repair gene; on the other hand, the combined pesticides decreased expression of one of the Non-homologous end joining (NHEJ) repair genes, called Xrcc6. Moreover, although only terbufos or fenthion managed to lessen XRCC2 protein expression, Ku70 affected all cells treated irrespective of up- or downregulation. In zebrafish embryos, fenthion was found to be the only effective substance to cause HR genes (Rad51 and Rad18) to experience disruption following exposure for 24 h; in contrast, the combined pesticides increased the level of Rad51 and Xrcc2 (HR genes) expression while at the same time impeding Rad51, Rad18, Xrcc2, and Xrcc6 genes with terbufos or fenthion only. Furthermore, fenthion or the pesticide combination impaired the hatching rate of zebrafish. To conclude, terbufos, fenthion, and the combined pesticides induced DSBs in the HepG2 cells and zebrafish embryos. Furthermore, we found terbufos and fenthion show antagonism in combination and reduce the toxicity in HepG2 or zebrafish embryos, this is a novel finding. | en_US |