The single cell green alga, Chlamydomonas, has two whip-like flagella that are used for swimming. If the flagella are mechanically removed by vigorous agitation, they grow back rapidly. During regrowth a family of genes that encode the flagellar structural proteins, alpha-and beta- tubulin, are activated and produce copious amounts of RNA and protein. Once the flagella have completely regrown, the tubulin genes becomes inactive. The objective of the proposed work is to elucidate the molecular mechanism responsible for tubulin gene regulation. In tubulin gene that are necessary and sufficient for on-off switching. The experimental approach to be used involves gene transfer techniques, and the use of isolated nuclei. The principal investigator also describes experiments designed to isolate and characterize proteins in the nucleus that bind to the tubulin gene regulatory regions, and as a consequence, somehow activates or inactivates the genes. One of the central questions in biology today concerns the mechanism involved in the regulated expression of genes in higher plants and animals. This mechanism is fundamental to such processes as growth and development. This proposal, then, approaches a timely and important problem by developing and exploiting a model system ideally suited for the analysis of gene expression.
