EFFECTS OF WATERBORNE HEXAVALENT CHROMIUM (Cr⁶⁺) EXPOSURE ON CR BIOACCUMULATION, IGF2, GLUT2 AND PPARG EXPRESSION ON GROUPER EMBRYO DEVELOPMENT

To investigate the bioaccumulation and genotoxicity of waterborne hexavalent chromium (Cr⁶⁺) in the embryos of the grouper (Epinephelus coioides), the embryos were exposed to a gradient levels of hexavalent chromium (0, 0.2, 0.6, 1, 5, 10, 20, 40, 60 and 80 mg/L) for 30 hours to measure the Cr bioaccumulation and the mRNA expression levels of cell growth gene igf2, nutrient metabolism genes glut2 and pparg at the morula stage, the blastula stage, the late gastrula, the brain vesicle stage and the heart beating stage. The results showed that the Cr bioaccumulation and the uptake rate increased with the increased waterborne Cr⁶⁺, but the uptake rate decreased with the development of the embryo. The morula stage had the strongest ability to absorb waterborne Cr⁶⁺, which is 20 times that of the heart beating stage. At the morula stage, blastula stage and late gastrula, the waterborne Cr⁶⁺ exposure significantly promoted igf2 and glut2 mRNA expression, while it clearly inhibited the pparg mRNA expression (P<0.05). At the late gastrula and the brain vesicle stage, the waterborne Cr⁶⁺ exposure enhanced significantly pparg mRNA expression (P<0.05). These findings demonstrated that the waterborne Cr⁶⁺ exposure had a significance effect on the Cr bioaccumulation, cell growth and nutrient metabolism of grouper embryos, which provide a theoretical basis for the grouper embryos protection in the aquatic environment.