RUI: Characterizing the Role of Regulatory Genes in Adaptive Evolution to Complex Environments

California State University-Dominguez Hills Foundation, Carson CA

Investigators

Abstract

This work will characterize a fundamental mechanism of evolution, not only leading to a better understanding of the evolutionary process, but eventually allowing for prediction of evolutionary outcomes. The investigators will use experimental evolution, a technique where organisms are evolved in the laboratory under strict conditions, allowing the PI to probe basic questions about the evolutionary process. This process will allow the PI to understand the role of advantageous mutations, including in genes that affect expression of other genes. These types of mutations may be particularly advantageous for organisms in changing environments. This work will be performed in collaboration with undergraduate and master's students at a Hispanic and Minority Serving Institution (HSI and MSI), where almost 90% of students are from groups underrepresented in STEM fields. Further, the PI will integrate this project into her upper division microbiology course as an authentic research experience for 24-48 undergraduate students per year, and perform outreach activities related to this project with K-12 educators. In these ways, the research will help to increase the diversity of students entering the STEM pipeline and leave them better prepared for roles in STEM fields. Changes in gene regulation are a driving force for evolution. Cis regulatory elements are often the cause of evolutionary change when comparing different species, whereas trans regulatory elements are often altered when organisms need to adapt to changing environments. Experimental evolution studies with microbes have begun to probe the role of these factors, but often in unchanging environments where either functional or cis regulatory changes would be favored. The PI will explore the role mutations in trans regulatory elements play in adaptation to a heterogeneous environment by focusing on mutations identified in two regulatory genes, cytR and sspA, that they have shown are adaptive in long-term cultures of Escherichia coli in complex media. To characterize their role in adaptation, the PI will first correlate the adaptive genotype with the transcriptome of the population to identify gene expression changes, and determine which of those changes confer the adaptive phenotype. The PI will then perform experimental evolution on mutant cells to determine how these mutations may change the evolutionary pathways cells can use to adapt to a heterogeneous environment. Understanding how these types of regulatory changes affect adaptation will contribute to the fundamental understanding of evolutionary principles.