RegA, RegA Homologs, and Control of Cellular Differentiation in Volvox Carteri

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Stephen M. MillerProposal # IOS-0744719regA, regA homologs, and control of cellular differentiation in Volvox carteriPlants and animals evolved long ago from single-celled (unicellular) ancestors. A critical early step in this process was the invention of multicellularity?the ability to make more than one cell type. But because plants and animals possess so many cells and types of cells, and because they have been evolving for so long, it has been very difficult to determine at a genetic level just how they came to be multicellular. That is, it is unclear which types of genes or changes in genes might make it more likely for a species of single-celled organisms to make descendants that possess more than one cell type. This project seeks to answer this problem using species of green algae (multicellular Volvox carteri and unicellular Chlamydomonas reinhardtii) that are close relatives of plants but simpler and better suited to study the evolution of multicellularity. Experiments will focus on a family of genes (regA and related genes) that evolved differently in Volvox and Chlamydomonas and that are believed to control the ability to make different cell types. To determine how multiple cell types are made in Volvox and how the ability to make more than one type of cell evolved in this organism, molecular genetic methods will be used to identify genes that are controlled by regA, and to compare the actions of regA-related genes in Volvox and Chlamydomonas. It is expected that these experiments will show how genes can change in relatively subtle ways over time to bring about monumental biological change. These studies should greatly improve the understanding of how complex organisms like plants and animals evolved, and will provide an easily teachable example of how evolution works at the level of the gene to produce new types of cells and organisms. An important broader impact of this project is that two female minority Ph.D. students who have great potential for long and successful careers in academic research will carry it out. They will increase the representation of underrepresented groups in the sciences, and their example and guidance should inspire many other minority students to pursue careers in science.