Comparative toxicity study of Water Borne Two Booster Biocides (CuPT and ZnPT) on embryonic flounder

Abstract

A new generation of booster biocides, including the metal pyrithiones (PTs) such as copper pyrithione (CuPT) and zinc pyrithione (ZnPT), has been increasingly used as a tributyltin substitute. In the marine environment, ZnPT can easily transchelate Cu to form CuPT, and the environmental fate and persistence of these two metal pyrithiones are closely related. Although some data regarding the toxicity of biocides in marine organisms are available, little is known about their sublethal toxic pathways or mechanisms in marine fish. We thus compared the toxic effects of two booster biocides on embryonic flounder by investigating their effects of developmental malformation and transcriptional changes. In our study, the toxic potency of CuPT was greater with respect to developmental malformation and mortality than ZnPT. Consistent with the developmental effects, the expression of genes related to tail fin malformation (including plod2, furin, and wnt3a) was greater in embryonic flounder exposed to CuPT than in those exposed to ZnPT. In analyses of differential gene expression profiles (fold change of genes with a cutoff P < 0.05) as assessed using high-throughput RNA sequencing, genes associated with muscle development and nervous system development were significantly changed commonly. Gene ontology analysis of embryos exposed to CuPT revealed affected cellular respiration and kidney development, whereas genes associated with cell development, nervous system development and heart development showed significant variation in embryos exposed to ZnPT. Overall, our study clarifies the common and unique developmental toxic effects of CuPT and ZnPT through transcriptomic analyses in a non-target species, embryonic flounder.