Stress responsive genes expression in intestine, liver and muscle of marine medaka fish

Abstract

To monitor the impact of organic pollutants on health of aquatic ecosystem, the molecular biomarker studies have been approached in various organisms. In this study we used the stress responsive genes such as catalase (CAT), cytochrome P450 (CYP1A), glutathione peroxidase (GPX), glutathione reductase (GR), glutathione S-transferase (GST), superoxide dismutase (SOD) and ubiquitin (UB) as biomarkers to investigate the effects of organic pollutant on transcriptional changes in intestine, liver and muscle of marine medaka fish (Oryzias javanicus). Marine medaka fishes were exposed to a variety of concentrations of organophosphorus pesticide, iprobenfos, then the organic pollutant induced transcriptional changes of 7 stress responsive genes in 3 tissues were analyzed by using quantitative RT-PCR. Pretreatment of medaka fishes in vivo with iprobenfos produced a marked induction of CAT, GPX and UB gene expression (>5 fold) in liver and also CYP1A, GR, GST, G6PD and SOD gene expression in liver increased significantly comparing with non-exposed control fish. The mRNA levels of those stress responsive genes in other 2 tissues, intestine and muscle were changed at certain exposure conditions but the changes in liver were the most remarkable comparing with other tissues. In particular, some of those gene expressions in muscle did not show a significant change in low dose of exposure. This study suggests that transcriptional changes in these 7 genes can be a good biomarkers to detect stress levels in Oryzias javanicus and also may be used for monitoring environmental exposure to organophosphorus pesticide.