One of the most remarkable feats to be accomplished during the transformation of a fertilized egg into a complex organism is the production of many different specialized cell types, but precisely how this task is achieved is not well understood. The multicellular green alga Volvox carteri is an excellent organism in which to investigate this issue because Volvox is developmentally very simple, possessing just two different cell types: large reproductive cells called gonidia, and small motile cells called somatic cells. The glsA (for gonidialess) gene is essential for the production of the large cells that become gonidia, and encodes a protein (GlsA) that is closely related to human, rat, and mouse proteins whose accumulation are positively correlated with cell division/proliferation and cancer. Recently work from this lab showed that GlsA associates with at least two other proteins (DP and Hsp70A), one of which (DP) is related to a known regulator of cell division in both higher plants and animals. The goals of the current project are to determine whether these proteins, like GlsA, are also required to produce cells of two different sizes and functions, and to determine how they do so. To accomplish these aims, established molecular procedures will be used to 1) generate Volvox variants that express reduced amounts of DP and Hsp70A and 2) to clone additional genes that encode factors required to produce cells of different sizes and fates. It is anticipated that these studies will provide insights into the manner in which cell division and cell differentiation are coupled in Volvox, and perhaps also in crop plants and humans as well. Furthermore, the students who complete these studies will receive valuable training toward careers as independent researchers.
