Faculty Mentor(s)

Dr. Erika Calvo-Ochoa, Biology

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Hypoxia, the lack of sufficient oxygen in tissues to sustain bodily functions, has a deleterious effect on physiological and behavioral health. Unlike mammalian brains, which are restrained in their capacity to recover following damage and hypoxic injury, zebrafish are an excellent model to study exposure to hypoxia due to substantial neuroplasticity mechanisms within their brain. Specifically, the olfactory bulbs (OBs) display high neuroplasticity and neurogenesis (i.e., generation of new neurons), making it a useful model to study neural responses under stressed environmental conditions such as hypoxia. Here, we establish a new paradigm of hypoxic exposure in zebrafish to uncover the effects of oxygen deprivation on the olfactory system. To induce hypoxia, we displaced dissolved O2 (DO) by perfusing N2 gas into the water until we reached hypoxic levels of 0.6-0.8 mg/mL DO compared to the normoxic (control) DO of 5.0 mg/mL. We then allowed zebrafish to recover for either 1-hour post hypoxia (1 hph) exposure or 1-day post hypoxia (1 dph). To measure the efficacy of our hypoxic conditions, we stained for active mitochondrial dehydrogenase activity, determined by triphenyl tetrazolium chloride (TTC) staining. To assess degeneration in the OBs, we performed immunohistochemistry assays to label astrocytes through Glial fibrillary acidic protein (GFAP) staining and cells undergoing apoptosis through Terminal deoxynucleotidyl transferase biotin-dUTP nick end labeling (TUNEL). We observed decreased TTC staining which suggests mitochondrial activity reduction, (indicative of neural death or damage) caused by hypoxia in the olfactory bulbs. In addition, we found that at 1 dph, the OBs present an increase in astrocyte activation and cells undergoing apoptosis. Overall, these findings validate hypoxia as an injury model for studying degeneration and regeneration in zebrafish. This research can give insights into further understanding of hypoxia’s impact on the body, specifically on olfactory morphology.


Research reported in this publication was supported in part by funding provided by the National Aeronautics and Space Administration (NASA) under award numbers G00028549 and G00028550, Michigan Space Grant Consortium and the Biology Department of Hope College.

Title on poster differs from abstract booklet. Poster title: Olfactory Dysfunction Following Oxygen Deprivation in Zebrafish