A comparative study of RNA-seq analysis on two marine embryonic fish exposed to Iranian Heavy Crude Oil

Abstract

This study clarifies the comparative developmental effects of Iranian heavy crude oil (IHCO) on the different toxic sensitivities of transcriptional responses between fish species and the weathering status of crude oil. We utilized high-throughput (Illumina RNA-seq) to characterize the developmental toxic effects from oil exposure. The assembled contigs contain 66,070 known unigenes in flounder and 76,498 known unigenes in spotted seabass. Comparison of different gene expression profiles reveals that the numbers DEGs are differentially higher up and downregulated in embryonic seabass than those of embryonic flounder exposed to fresh IHCO (FIHCO) and weathered IHCO (WIHCO). Gene pathway analysis from the most differentially expressed gene set was classified from crude oil exposure: indicated the oxidative phosphorylation, disease pathway (Parkinson’s, Alzheimer’s, Huntington’s disease) and cardiac muscle contraction. The expression patterns of 13 differentially expressed genes were validated by quantitative real-time RT-PCR (average correlation cutoff p< 0.005). Especially, the level of genes involving detoxification (CYP1A, CYP1B1 and CYP1C1) in embryonic seabass increased higher than those of flounder but the other genes involving cell processing, development and immune system changed higher in flounder exposure to FIHCO and WIHCO. In differentially orthologous gene clusters analysis, embryonic flounder seem likeoughput (Illumina RNA-seq) to characterize the developmental toxic effects from oil exposure. The assembled contigs contain 66,070 known unigenes in flounder and 76,498 known unigenes in spotted seabass. Comparison of different gene expression profiles reveals that the numbers DEGs are differentially higher up and downregulated in embryonic seabass than those of embryonic flounder exposed to fresh IHCO (FIHCO) and weathered IHCO (WIHCO). Gene pathway analysis from the most differentially expressed gene set was classified from crude oil exposure: indicated the oxidative phosphorylation, disease pathway (Parkinson’s, Alzheimer’s, Huntington’s disease) and cardiac muscle contraction. The expression patterns of 13 differentially expressed genes were validated by quantitative real-time RT-PCR (average correlation cutoff p< 0.005). Especially, the level of genes involving detoxification (CYP1A, CYP1B1 and CYP1C1) in embryonic seabass increased higher than those of flounder but the other genes involving cell processing, development and immune system changed higher in flounder exposure to FIHCO and WIHCO. In differentially orthologous gene clusters analysis, embryonic flounder seem like