Evolution of Development and Physiology
Howard, Alicia D. , Duncan, Leonard , Buckley, Stephanie , Miller, Stephen M. .
Analysis of an ortholog and paralogs of regA, a cell-type regulator in Volvox carteri f. nagariensis.
Little is known about the molecular basis of the transition from unicellularity to multicellularity with cellular differentiation, primarily because of a lack of extant model organisms in lineages containing close unicellular and multicellular relatives. Volvox carteri is an excellent model for studying the evolution of cellular differentiation mechanisms. It is closely related to extant volvocine green algae that are unicellular or multicellular with no or incomplete division of labor between cell types. It shares a common ancestor with unicellular Chlamydomonas reinhardtii, that lived only ~50 MYA. V. carteri forma nagariensis has two cell types: large reproductive gonidia and small motile somatic cells. The somatic regenerator gene (regA), encodes a product (RegA) that represses reproductive potential in somatic cells. RegA bares no primary sequence homology to other proteins in sequence databases, but is enriched in amino acids commonly found in transcription factors. Analysis of the predicted secondary structure revealed that RegA contains a VARL (Volvocine Algal RegA-like) domain that resembles the poorly conserved SAND DNA-binding domain. Searches of the annotated C. reinhardtii and the assembled V. carteri genomes have revealed several genes in both genomes that potentially encode VARL domains. Taken together, the available evidence suggests that members of this multigene family were likely involved in the transition to cellular differentiation in the volvocine lineage. The goals of this project are to 1) characterize an upstream regA paralog (rlsA) to determine if it functions in cellular differentiation; and 2) determine whether or not the other V. carteri regA-like sequence genes (rls) encode VARL domains, and under what conditions they are expressed.
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1 - University of Maryland Baltimore County, Biological Sciences, 1000 Hilltop Circle, Baltimore, MD, 21250, USA
2 - University of Texas Southwestern Medical Center, Department of Cell Biology
3 - University of Maryland Baltimore County, Biological Sciences
Presentation Type: Plant Biology Abstract
Location: Exhibit Hall (Northeast, Southwest & Southeast)/Hilton
Date: Sunday, July 8th, 2007
Time: 8:00 AM