EAGER: Environmental nitrite is a nitric oxide donor that modulates fish olfactory function.

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This project explores a novel hypothesis about the sense of smell (olfaction) in bony fishes. In mammals, detection of smells and brain integration of olfactory information can be mediated by nitric oxide that is produced in the brain mainly by oxygen-dependent (aerobic) processes. Fishes often live in oxygen-poor environments in which aerobic production of nitric oxide is inhibited. Thus, it is unknown how nitric oxide-dependent smell sensation occurs in fishes when in low-oxygen environments, conditions that are becoming more common in a warming climate. The project will investigate how goldfish uptake aquatic nitrogenous compounds within the nose, and how nitric oxide is generated to control neuronal function, even under low-oxygen conditions. The results of this research will be applicable to other fishes, including aquacultured species such as trout, and thus could have direct applications in fish farming and may help to inform conservation efforts. The goals of the project’s integrated education components are to enhance the success of Hispanic and other underrepresented graduate students at Texas State University (a Hispanic Serving Institution), focusing especially on building science communication writing skills, which can ultimately be used to inform the local community about the relevance of the sense of smell in natural populations.The role of nitric oxide in olfactory processes is complex and poorly understood. Moreover, little is known about how this signaling molecule modulates olfaction in aquatic vertebrates. This research will use goldfish as a model to test whether environmental nitrite is actively taken up from the water via a chloride-carbonate anion-exchange transporter protein in the nasal epithelium of teleost fishes, accumulated there, and then transported into the central nervous system to be used as a nitric oxide donor to control neuronal function. The project will also test whether nitric oxide can be produced by non-oxidative pathways (via heme proteins and molybdenum enzymes), thus ensuring olfactory function even in hypoxic or anoxic conditions. The project is considered to be potentially transformative because, if the hypotheses are supported, the project will establish a new mechanism to detect and transfer olfactory sensory information to the brain, and lead to new directions in the field of fish sensory biology. A post-doctoral fellow and a graduate student trainee, recruited from groups underrepresented in science, will be involved in the research, and an annual writing workshop will meet an identified need for development of graduate students’ scientific communication skills. The award will also add to the research resources at the institution.This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.