Subterranean Fishes of the World

3223

2013

AIM 2013

While sleep is a near-universal behavior throughout animal kingdom, its function and evolutionary basis remain unclear. Sleep quantity and quality are regulated by metabolic state. Neural regulation of sleep, appetite and energy homeostasis is critical for an animal’s survival and under stringent evolutionary pressure. Across phyla, starvation results in reduced or disrupted sleep suggesting animals suppress sleep in order to forage for food. Understanding the evolutionary basis for sleep loss in nutrient poor environments will provide critical insight into how animals adapt to an altered habitat. We are currently investigating the biological basis of sleep in the Mexican cavefish Astyanax mexicanus, a model system for investigating evolutionarily derived sleep loss. It is possible that cavefish sleep less than surface fish because they are more sensitive to small perturbations in food availability. Alternatively, these sleep changes could be evolutionary hard-wired, as an adaptation constant nutrient shortage in caves. To differentiate between these two possibilities we are currently rearing fish on high and low calorie diets to determine whether high-metabolic stores can rescue the reduced sleep in cavefish. We are collaborating with Erik Duboue and Richard Borowsky (NYU) to pharmacologically interrogate the molecular basis for reduced sleep in cave populations. Blocking ß-adrenergic signaling with propranolol increases sleep in cavefish while having no effect on surface fish raising the possibility that increased catecholamine signaling is responsible for reduced sleep in A. mexicanus cave populations. We are currently using RNA-seq in starved or sleep-deprived cave and surface populations to determine additional molecular pathways that may underlie reduced sleep in cave populations. Additionally, we are examining cortisol levels, a conserved indicator of stress and sleep deprivation, to determine whether cave populations are chronically sleep deprived or have evolved reduced sleep need.

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