| 摘要: | 本研究使用人類肝臟細胞HepG2和斑馬魚胚胎評估單獨或混合有機磷農藥terbufos和fenthion的毒性，以確定遺傳毒性機制。我們使用單細胞凝膠電泳實驗和 H2AX 磷酸化 (γH2AX) 分析遺傳毒性，結果顯示細胞在與terbufos和/或fenthion相互混合時會導致 DNA 雙鍵斷裂 (DSB)。當濃度為40 ?M，複合藥物幾乎沒有藥物毒性、基因毒性以及對同源重組 (HR) 活性的影響。在 HepG2 細胞，當細胞處理藥物後，同源重組(HR) 修復基因Xrcc2表達降低；另一方面，複合藥物也降低了非同重組NHEJ 修復基因Xrcc6的表達，此外，儘管只有 terbufos或fenthion可降低 XRCC2 蛋白表達，有機磷農藥仍可影響所有處理過的細胞Ku70的表達，無論是正調控還是負調控。在斑馬魚胚胎實驗中，暴露在有機磷農藥24 小時後，fenthion是造成 HR 基因（Rad51 和 Rad18）發生破壞的唯一有效物質；相比之下，複合藥物增加了 Rad51 和 Xrcc2（HR 基因）的表達水平，單獨使用terbufos或fenthion則阻礙了 Rad51、Rad18、Xrcc2 和 Xrcc6 基因表達。此外，fenthion或複合藥物降低斑馬魚的孵化率。總之，terbufos、fenthion和複合藥物在 HepG2 細胞和斑馬魚胚胎中誘導了 DNA 雙鍵斷裂。此外，我們發現terbufos和fenthion複合藥物顯示出拮抗作用並降低HepG2和斑馬魚胚胎的毒性，這是一個新發現。;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 ?M), 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. |
