Date of Defense

4-16-2025

Date of Graduation

4-2025

Department

Biological Sciences

First Advisor

Andrew Thompson

Second Advisor

Pamela Hoppe

Abstract

Rio Pearlfish (Nematolebias whitei) have unique adaptations that enable survival in harsh, fluctuating environments. This species lives in small puddles that dry up biannually. During the dry season, Rio Pearlfish adults die, whereas embryos undergo a unique form of dormancy known as diapause. When the wet season returns, the embryos stop dormancy and hatch, allowing the species to survive. This unique life cycle makes Rio Pearlfish an ideal model organism for studying ecology, evolution, and development. A better understanding of Rio Pearlfish diapause will contribute to a better overall understanding of environmental adaptations, conservation, vertebrate evolution, genetic diseases, and mammalian “hatching.”

This project specifically investigates how the Rio Pearlfish genetically controls diapause. In this study, the genetic mechanisms behind diapause are analyzed through a DNA sequencing technique known as ATAC-Seq. The primary goal of this research is to better understand the expression and regulation patterns of genes controlling hatching delay and diapause in killifishes. While little is known about the molecular mechanisms of this dormancy, it is understood that these organisms stop growing and lower their metabolism. Thus, this study investigates the hypothesis that 1.) diapause in Rio Pearlfish is controlled by repression of RNA production via chromatin condensation during diapause followed by its reactivation via chromatin decondensation upon hatching, and 2.) Rio Pearlfish suppress cell cycle progression until hatching by downregulating cell cycle checkpoint genes during diapause via chromatin condensation.

Access Setting

Honors Thesis-Restricted

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