Examination of pigmentation differences in cave and surface Astyanax mexicanus using in situ hybridization

Abstract

By Ayana Phelps, Biological Sciences/Spanish

Advisor: Joshua Gross

Presentation ID: AM_ATRIUM22

Abstract: The extreme environment of the cave has contributed to several phenotypic differences between the cave and surface-dwelling morphs of Astyanax mexicanus. One obvious difference is reduced pigmentation in the cavefish compared to closely-related surface-dwellers. To understand this extreme cave phenotype, we evaluated gene expression differences that may underlie these differences. We examined five genes associated with three pigmentation cell types: iridophores, xanthophores, and melanophores. Utilizing in situ hybridization, we visualized gene expression levels and patterns across three developmental stages (24 hours post fertilization [hpf], 36 hpf, and 72 hpf) in two independent cavefish populations and compared them to surface fish. Our results reveal substantial expression level differences between cave and surface fish, however spatial patterns tend to be similar between morphs. Future studies will determine if early gene expression differences have a functional impact, which explains natural pigmentation differences between cave and surface-dwelling fish.