Stress-responsive genes (hsp70 and mt) and genotoxicity elicited by roxarsone exposure in Carassius auratus.

In this study, comet assay (single-cell gel electrophoresis), real-time quantitative PCR (qPCR) and proteomics approach were used to comprehensively assess toxicity elicited by roxarsone exposure in C. auratus at 50, 150 and 300 μg/L for 7, 14 and 21 days. Results of comet assay showed that DNA were seriously damaged under the pressure of roxarsone, especially the concentration of 50 μg/L that always maintained a sustained and increased damage effect to fish liver cell during the 21 days experiment. The expressions of biomarker genes showed that hsp70 gene expressions raised significantly and the group of 50 μg/L also showed a continued increased response effect, whereas mt gene was only slightly increased. Results of proteomics for the concentration of 300 μg/L found that thirty six significantly changed proteins were identified by MALDI-TOF/TOF-MS. They are involved in many important processes including energy producing, cytoskeleton stabilization, substance metabolism and stress response. Among these metabolites, carbohydrate metabolism (mainly occurred during day 1-14) and cytoskeleton proteins (mainly occurred during day 14-21) were the most identified proteins. These results revealed that the low levels of 50 μg/L probably led to a continuous damage than the higher groups during the experiment time. Furthermore, proteomics results might implied that though cell system expected to mobilize almost all the functional proteins to quickly establish a new homeostasis together when facing the roxarsone at first, but in the end the destroyed cell cytoskeleton structure might burst the bubble.