Genome-wide maps of chromatin state in liver cells of Astyanax mexicanus [ChIP-seq]
Organisms adapt to and survive in environments with varying nutrient availability. Cis-regulatory changes play important roles in adaptation and phenotypic evolution. To what extent cis-regulatory elements contribute to metabolic adaptation is less understood. Here we have utilized a unique vertebrate model, Astyanax mexicanus, that survives in nutrient rich surface and nutrient deprived cave water to uncover gene regulatory networks in metabolic adaptation. We performed genome-wide analysis of accessible chromatin and histone modifications in the liver tissue of one surface and two independently derived cave populations, providing the first genome-wide epigenetic landscape in this organism. We find that many cis-regulatory elements differ between surface and the cavefish, while the two independently derived cave populations have evolved remarkably similar regulatory signatures. Changes in gene regulatory networks between the surface and cave morphotypes point to global changes in key metabolic pathways. Overall design: Chromatin profiles of H3K4me3, H3K27Ac, and H3K27me3 by immunoprecipitation in liver tissue from 2 or 3 replicates each of Surface, and Pachon and Tinaja cave variants of Astyanax mexicanus.