Meiotic eukaryotic sex is thought to have originated at least 600 million years ago. Its most familiar manifestations occur in the germ-line tissues of multicellular plants and animals, but most modern single-celled eukaryotes, including yeasts, ciliates, and algae, also engage in meiotic sex, and it is assumed that meiotic sex first arose in unicells and provided the basis for the evolution of multicellularity. Since sex and speciation are intimately intertwined, an understanding of biodiversity is critically dependent on an understanding of how sexual strategies operate and evolve. This project is focused on two closely related species of unicellular green algae, Chlamydomonas reinhardtii and Chlamydomonas incerta, that have very similar 'housekeeping genes' but whose sex-related genes are highly divergent. Previous support from the NSF has enabled this laboratory to identify and clone genes that govern sexual differentiation and zygote maturation in these organisms, including genes resident in the key mating-type locus. The current project will continue the analysis of their function and their evolution. The project focuses on three genes. 1) The Mid gene product induces cells to differentiate as mating-type minus and suppresses the plus differentiation pathway; experiments are designed to identify proteins that participate with the Mid protein in effecting this transcriptional regulation. 2) The Iso1 gene encodes a chromatin-remodeling factor in the ISWI family that is up-regulated in response to nitrogen starvation -- the environmental signal that initiates sexual differentiation -- and is necessary for expression of gamete-related genes; experiments are designed to understand its mode of regulation, its target genes, and its relationship to Mid expression. 3) The Gsp1 gene product is involved in the expression of zygote-specific genes following gametic cell fusion; experiments are designed to understand how this transcriptional regulation is effected.
|Effective start/end date||15/07/03 → 31/12/07|
- National Science Foundation: $810,000.00