Identification of possible hypoxia sensor for behavioral responses in a marine annelid, Capitella teleta

Hypoxia often occurs in summer and causes deleterious effects on marine benthic animals. A marine annelid, Capitella teleta , has tolerance to hypoxia, as shown by the fact that it inhabits organically polluted area, 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 C. teleta . To examine the involvement of TRPA1 in the response of C. teleta to hypoxia, we exposed C. teleta to hypoxic water with or without a TRPA1-specific inhibitor, A-967079. Hypoxic stimulation induced escape behavior of C. teleta from the sediment, and this behavior was suppressed by the inhibitor. The cloned TRPA gene from C. teleta was phylogenetically categorized into TRPAbasal , and contains an oxygen-dependent degradation domain, which is important for the detection of hypoxia. Whole-mount in situ 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 organism9s niches in hypoxic environments by detecting whether hypoxia exceeds a level that would imperil its survival.