Oxygen chemoreceptors in aquatic vertebrates

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The control of oxygen uptake is important to all vertebrates for survival during periods of low oxygen (hypoxia). Specialized cells, called oxygen chemoreceptors, detect changes in blood or environmental oxygen and initiate a cascade of events that ultimately leads to physiological changes in respiratory rate and cardiovascular function. While many studies have described these cells in mammals, oxygen chemoreceptors are poorly defined in aquatic vertebrates, such as fish and amphibians. This Discovery Grant application proposes research to fill these voids and: (i) determine the role of membrane ion channels and intracellular factors in 'shaping' the oxygen chemoreceptor response to hypoxia in zebrafish and goldfish, (ii) study the synaptic physiology between chemoreceptors and sensory neurons in the gill using a novel experimental approach, and (iii) characterize the first physiological response of a skin oxygen chemoreceptor at the cellular level. The proposed experiments will include sensitive patch-clamp electrophysiological recording and microspectrofluorimetry of isolated chemoreceptors, high-resolution confocal microscopy, and behavioural studies. This research will provide the first description of the cellular and neurochemical basis of oxygen sensing in the gill, and the development of these processes from embryos to adults. This research will also provide a greater understanding of how respiratory regulation may have evolved. These findings will constitute significant advances in the fields of oxygen sensing, neurobiology, development and comparative physiology. The program will support the training of an average of 4 graduate students per year at the M.Sc. or Ph.D. level, in addition to numerous undergraduate students.