The toxic effects of crude oil on the fish early life stage

Abstract

This study clarifies the comparative developmental toxic effects of Iranian Heavy Crude Oil (IHCO) between embryonic spotted seabass (Lateolabrax maculates) and olive flounder (Paralichthys olivaceus). From 24 hrs after exposure to IHCO, several complex effects, including the pericardium edema, spinal curvature, developmental delay and tail fin malformation were observed in both of embryonic fish. The extent of edema, spinal curvature and developmental delay in olive flounder were stronger than those of spotted seabass in oil exposed groups, whereas the levels of CYP1A expression were lower than those of spotted bass. Here, we utilized high-throughput RNA-seq to characterize the developmental toxic effects of the crude oil. The assembled contigs contained 16,942 known unigenes in flounder and 167,049 known unigenes in spotted seabass in this study. Comparison of different gene expression between exposed to crude oil and control samples revealed that the number of 97-108 genes differently up-regulated but 448-419 genes differently down-regulated at 4 hrs following exposure. Gene pathway analysis of the differently expressed gene set indicated the immune and embryonic heart tube development, cell signaling responses. The expression patterns of thirteen differently expressed genes were validated by quantitative real-time RT-PCR (average correlation cutoff p<0.001). Over all, these findings implicated that the embryoniveral complex effects, including the pericardium edema, spinal curvature, developmental delay and tail fin malformation were observed in both of embryonic fish. The extent of edema, spinal curvature and developmental delay in olive flounder were stronger than those of spotted seabass in oil exposed groups, whereas the levels of CYP1A expression were lower than those of spotted bass. Here, we utilized high-throughput RNA-seq to characterize the developmental toxic effects of the crude oil. The assembled contigs contained 16,942 known unigenes in flounder and 167,049 known unigenes in spotted seabass in this study. Comparison of different gene expression between exposed to crude oil and control samples revealed that the number of 97-108 genes differently up-regulated but 448-419 genes differently down-regulated at 4 hrs following exposure. Gene pathway analysis of the differently expressed gene set indicated the immune and embryonic heart tube development, cell signaling responses. The expression patterns of thirteen differently expressed genes were validated by quantitative real-time RT-PCR (average correlation cutoff p<0.001). Over all, these findings implicated that the embryoni