Tissue-Biased and Species-Specific Regulation of Glutathione Peroxidase () Genes in Scallops Exposed to Toxic Dinoflagellates.

Marine bivalves could accumulate paralytic shellfish toxins (PSTs) produced by toxic microalgae, which might induce oxidative stress. Glutathione peroxidases (GPxs) are key enzymes functioning in the antioxidant defense, whereas our understanding of their roles in PST challenge in bivalves is limited. Herein, through genome-wide screening, we identified nine () and eight () genes in Zhikong scallop () and Yesso scallop (), respectively, and revealed the expansion of GPx3 sub-family in both species. RNA-Seq analysis revealed high expression of scallop s after D stage larva during early development, and in adult hepatopancreas. However, in scallops exposed to PST-producing dinoflagellates, no was significantly induced in the hepatopancreas. In scallop kidneys where PSTs were transformed to higher toxic analogs, most s were up-regulated, with s being acutely and chronically induced by and . exposure, respectively, but only one from subfamily was up-regulated by . exposure. Our results suggest the function of scallop s in protecting kidneys against the oxidative stresses by PST accumulation or transformation. The tissue-, species-, and toxin-dependent expression pattern of scallop s also implied their functional diversity in response to toxin exposure.