Connecting Environment and Phenotype: Deciphering Mechanisms of Diapause Entry and Exit in the Annual Killifish <i>Austrofundulus limnaeus</i>

Abstract

Embryonic development is complex, dynamic, and dependent on environmental factors. Mechanisms of sensing and integrating environmental stimuli are diverse, and understanding these mechanisms in extant species can elucidate how complex phenotypes emerge from genomic information expressed in an environmental context. In Austrofundulus limnaeus, an annual killifish with alternative developmental trajectories, light and temperature are vital factors that determine if an embryo will enter a state of diapause. We hypothesize that embryos of A. limnaeus use the vitamin D3 signaling pathway as a vehicle to incorporate these ecological signals into their developmental programing. Here we provide evidence of this pathway's importance in regulating both entrance into and exit from diapause. We use a pharmacological approach to explore this pathway and closely related hormone receptors on the regulation of diapause. Exposure of A. limnaeus embryos to metabolites found in similar invertebrate signaling pathways, as well as parallel studies performed on Danio rerio zebrafish embryos support a role for vitamin D3 signaling in the control of developmental progression. Further, we highlight key potential targets for the vitamin D3 pathway that may elicit exit from diapause through regulation of DNA methylation.