Oxygen sensing in crustaceans: functions and mechanisms

Animals that live in changing environments need to adjust their metabolism to maintain body functions, and sensing these changing conditions is essential for mediating the short- and long-term physiological and behavioral responses that make these adjustments. Previous research on nematodes and insects facing changing oxygen levels has shown that these animals rapidly respond using atypical soluble guanylyl cyclases (sGCs) as oxygen sensors connected to downstream cGMP pathways, and they respond more slowly using hypoxia-inducible transcription factors (HIFs) that are further modulated by oxygen-sensing prolyl hydroxylases (PHs). Crustaceans are known to respond in different ways to hypoxia, but the mechanisms responsible for sensing oxygen levels are more poorly understood than in nematodes and insects. Our paper reviews the functions of and mechanisms underlying oxygen sensing in crustaceans. Furthermore, using the oxygen sensing abilities of nematodes and insects as guides in analyzing available crustacean transcriptomes, we identified orthologues of atypical sGCs, HIFs, and PHs in crustaceans, including in their chemosensory organs and neurons. These molecules include atypical sGCs activated by hypoxia (Gyc-88E/GCY-31 and Gyc-89D/GCY-33) but not those activated by hyperoxia (GCY-35, GCY-36), as well as orthologues of HIF-alpha, HIF-beta, and PH. We offer possible directions for future research on oxygen sensing by crustaceans.

Automated summary

Animals living in changing environments must adjust their metabolism to ensure body functions, with nematodes and insects known to use atypical sGCs as oxygen sensors and respond through downstream cGMP pathways, while crustaceans' mechanisms for sensing oxygen levels are less understood. By analyzing crustacean transcriptomes using the guidance from nematodes and insects, researchers identified orthologues of atypical sGCs, HIFs, and PHs in crustaceans, offering potential directions for future research on oxygen sensing by crustaceans.