Meeting Abstract

P2.101  Thursday, Jan. 5  Sundials in the Void: Assessing Circadian Rhythms in a Cave Adapted Species CARLSON, B.M.*; GROSS, J.B.; University of Cincinnati; University of Cincinnati

The coordination of biological processes with the surrounding environment is critical to the success and survival of organisms. For instance, photic input (sunlight) entrains rhythmic gene expression, which in turn influences patterns in metabolism, activity and other biological “outputs”. It has long remained unclear how deviation from a normal light-dark phase can negatively influence these biological processes in organisms that do not encounter sunlight; regressive and constructive morphological traits are well characterized across many cave-dwelling species, but little is known about changes to physiological processes that normally rely on periodic photic input. We aim to explore this question by assessing the fate and function of circadian biology in Astyanax mexicanus, an emerging model fish system consisting of a derived, cave-dwelling morphotype and an extant, “ancestral” surface morphotype. Based on studies in other species, we expect to observe significant changes in the circadian biology of the cave morphotype, relative to the surface form, as a consequence of life in perpetual darkness. Presumably, these changes will manifest as a decoupling of circadian rhythms from photic input or even complete abandonment of circadian rhythmicity. To determine whether, and to what extent, a biological rhythm persists in A. mexicanus, we have devised a technique to measure and quantify activity patterns in adult surface, cave and hybrid fish. We also present preliminary data investigating potential structural and expression differences of candidate genes governing circadian rhythms in surface v. cave morphs. This work provides a starting point for exploring the presence v. absence of a persistent biological rhythm in A. mexicanus after millions of generations spent in the darkness of a cave.