35-7 Sat Jan 2 Development of the O2 sensing system in an amphibious fish Cochrane, PV*; Jonz, MG; Wright, PA; University of Guelph, ON, Canada ; University of Ottawa, ON, Canada; University of Guelph, ON, Canada cochranp@uoguelph.ca
Proper development of the O2 sensing system is essential for survival. However, the development of the O2 sensing system in animals can be altered by exposure to high/low O2 levels during early life. We characterized the development of the O2 sensing system in the mangrove rivulus (Kryptolebias marmoratus), an amphibious fish that transitions between hypoxic aquatic environments and O2-rich terrestrial environments. We found that the development of serotonergic O2-sensitive chemoreceptors (neuroepithelial cells; NECs) on the gills of K. marmoratus is accelerated relative to the only other species of fish studied to date, zebrafish, and that cutaneous NECs are retained from the larval stage to adulthood. We also found that the hyperventilatory response to acute hypoxia is present in embryonic K. marmoratus, indicating that functional O2-sensing pathways are formed during embryonic development. We then exposed embryos to aquatic normoxia, aquatic hyperoxia, aquatic hypoxia, or terrestrial conditions for the first 30 days of development and tested the hypothesis that environmental O2 availability during embryonic development modulates the development of the O2 sensing system in amphibious fishes. Surprisingly, we found that O2 availability during embryonic development did not influence the development or morphology of NECs on the gills and skin of K. marmoratus. Collectively, our results demonstrate that, unlike zebrafish, the development of the O2 sensing system is insensitive to environmental O2 levels during the embryonic stage, suggesting that life history differences may underlie interspecies variation in plasticity.
