Comparative toxicity of three alternative booster antifouling biocide on embryonic flounder (Paralichthys olivaceus) : An approach to transcriptome and morphogenesis

Abstract

The use of alternative biocides for antifouling application has increased since the restriction on the use of organotin compounds. However, there is the limited information of those biocides on the toxicity to nan-target marine organism. The present study determined the toxic effects of the alternative antifouling compounds including Diuron, Irgarol 1051 and Sea-nine 211 on embryonic flounder. At 48h after exposure, frequency percentage of mortality was <10% in all the exposure group of Irgarol 1051 and Diuron. But embryos were shown 100% of mortality in the exposure group of 100 ug/L for sea-nine 211. Overall, three biocides produced a largely overlapping suite of defects including caudal fin fold defects, dorsal curvature, and pericardial edema. Those biocides may be ranked in the following order from highest malformation and mortalities Sea-nine 211>Irgarol1051>Diuron. We used high-throughput sequencing (RNA-seq) to characterize the developmental toxic effects from biocide exposure. Genes associated with proteolysis involved in cellular protein catabolic pathway process, and intracellular signal transduction were down-regulated in flounder embryos treated with three biocides. Genes associated with microtubule cytoskeleton and regulation of cell morphogenesis were up-regulated at embryos exposed to Irgarol 1051 and Sea-nine 211, while they were down-regulated in embryos exposed to Diuron. Different gene expression profiles were also observed in embryos exposed to biocides with different chemical compositions. Overall, our study provides a better understanding of the underlying molecular toxic mechanisms via RNA-seq and DEGs in embryonic flounder.