REIBER, C.L.; University of Nevada,Las Vegas: Integrated hypoxic response: From the gene to behavior

Appropriate ontogeny of physiological regulatory mechanisms is critical for an animal’s ability to deal with environmental variables encountered at different developmental stages and varying periods during their life cycle. Selective pressures can be encountered at any point during an animal’s embryonic, larval or reproductive period. Thus, evolutionarily significant adaptations should be selected for at all stages of the life cycle. Investigations that focus on a few developmental stages or are limited to only a narrow view of the animal’s biology can overlook mechanisms that may allow an animal to survive a stress. Aerobic metabolism and oxygen limitations can be used to assess regulatory mechanisms across levels of complexity. Most animals rely on oxygen to support aerobic metabolism and the generation of ATP, and have a suite of compensatory responses that enable them to maintain oxygen delivery to tissues. While immediate physiological responses to hypoxia are readily observed in most species, there must also exist a cellular response to hypoxia. The molecular mechanisms involved in the response to hypoxia involve many genes that are regulated by oxygen via a DNA binding protein, HIF1. HIF induced gene products include erythropoietin (increased Hb production), VEGF (enhance vascularization) and glycolitic enzymes (enhance anaerobic metabolism). In many invertebrates, Hb is a large extra cellular protein composed of many subunits. In addition to increasing Hb concentrations, some animals are able to change the type of Hb produced. We have found that the tadpole shrimp elicits a broad array of response to hypoxic exposure, from the behavioral & physiological to the cellular & molecular level. This system lends itself nicely to investigating the integrated response toward maintaining aerobic metabolism. This work is supported by an NSF grant to C.L.R (IBN 9874534)