Fig. 5

Toxin resistance and response regulatory networks in the scallop kidney and hepatopancreas. a Amino acids conferring PST or TTX resistance on sodium channel Nav1 (highlighted in red) identified in this and other studies^{69, 75,76,77,78,79}. Skull signs indicate toxin-producing and -resistant species. b Expression of sodium channels Nav1 and Nav2, and PST concentration and toxicity levels in major organs of C. farreri. Toxicity (μg STX eq. per 100 g) was determined by converting total concentration of PSTs to micrograms of STX equivalents per 100 g of tissue⁸⁰. c Temporal variations in abundance of different PSTs and gene networks in the kidney and hepatopancreas after exposure to the toxic alga Alexandrium minutum. Toxin response modules were identified by enrichment analysis of DEGs during exposure to A. minutum and each module was annotated with the two most significantly enriched GO term(s). The green module is the largest kidney-specific response module, where cytosolic sulfotransferase (Sult) genes are enriched (Supplementary Data 10) and highly expressed on day 5 after A. minutum exposure (as indicated in the heat map). d A schematic diagram showing different roles of the scallop hepatopancreas and kidney in toxin metabolism, with the hepatopancreas primarily responsible for PST accumulation, whereas the kidney primarily for PST transformation mediated by SULTs