Abstract In invertebrates inhabiting hydrothermal vent areas, hypotaurine, a precursor of taurine, is thought to mitigate the toxicity hydrogen sulfide in fluids. Information about hypotaurine synthesis pathways limited, although two pathways, cysteamine [2-aminoethanethiol (AET)] pathway and cysteine sulfinate (CSA) are known mammals. this study, we cloned cDNA encoding AET dioxygenase (ADO), ...