CAREER: Establishing a new field of study dedicated to animal oxidase water

Water is critical for life. We know of no life form that can survive without it. In addition, an underappreciated phenomenon is that the chemical processes of life occurring within cells produce substantial amounts of new H2O as a byproduct. As a result, living beings are their own water factories. However, for animals, relatively little is known about the importance of internal water production versus other water sources (e.g., drinking water). A key constraint is that until recently, measuring internal water production was difficult and required at least two samples of body water (typically distilled from blood) collected days to weeks apart. This requirement complicates studies of captive animals and forces studies in the wild to depend on recaptures of previously sampled animals. Recently, a new method has been developed that can estimate internal water production based on a single sample, at a fraction of the cost of prior methods. This method creates a new frontier of biotechnology with application to essentially all living beings, and particularly to studies of animals that have previously been considered too difficult to conduct. Because internal water production is also tied to healthy cell functioning and the rate of energy use, fields ranging from wildlife biology to exercise science to space medicine stand to benefit from advancing this new analytical approach. This project uses the new method to assess how internal water production is influenced by fundamental aspects of animal biology: different diet compositions, thermoregulatory abilities, and variation in basic physiology between vertebrates versus invertebrates. This project also provides major educational benefits. Undergraduate and graduate courses generally lack teaching material focused on internal water production, because so few data are available; this project will translate research results into college-level teaching materials, including development of a new course. In addition, the underlying biotechnology has wide applications, thus this project will support a workshop for K-12 educators, focused on effective teaching of the key concepts. This teaching will prepare students to understand cutting-edge science as they enter the workforce and professional training. This project will assess the contributions of oxidase water (i.e., metabolically-produced water synthesized with assimilated atmospheric oxygen) to the total body water pool in a wide variety of animal taxa. Specific predictions, based on fundamental physiological hypotheses, are that: high metabolic rates of endotherms provide greater fractional input of oxidase water than in ectotherms; high temperatures cause endotherms to rely more heavily on oxidase water because of thermoregulatory water losses; and that carnivores rely more heavily on oxidase water than herbivores because of reduced food water intake. The central study method includes measuring Δ17O in body water (i.e., Δ17OBW), a novel variable that combines data from all three stable oxygen isotopes. The unique Δ17O value of atmospheric oxygen was recently shown to reflect the contribution of oxidase water—which contains atmospheric oxygen—to the total body water pool. 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.