Identification of Possible Hypoxia Sensor for Behavioral Responses in a Marine Annelid,

Hypoxia often occurs in summer and causes deleterious effects on marine benthic animals. A marine annelid, , is tolerant to hypoxia, as shown by the fact that it inhabits organically polluted areas, where severe hypoxia is often observed. To understand how this species adapts to the environment, we focused on its hypoxia sensor, and we showed that TRPAbasal was a possible contributor to hypoxia detection in To examine the involvement of TRPA1 in the response of to hypoxia, we exposed to hypoxic water with or without a TRPA1-specific inhibitor, A-967079. Hypoxic stimulation induced escape behavior in from the sediment, and this behavior was suppressed by the inhibitor. The cloned TRPA gene from was phylogenetically categorized into , and contains an oxygen-dependent degradation domain, which is important for the detection of hypoxia. Whole-mount hybridization analysis showed that the gene was transcribed in the prostomium, where sensing functions are localized. These results suggested that the worm has a hypoxia-sensing system possibly utilizing CtTRPAbasal, and this system contributes to expanding the organism's niches in hypoxic environments by detecting whether hypoxia exceeds a level that would imperil its survival.