PRECISE MAPPING OF THE HOMOTHALLISM GENES HML AND HMR IN SACCHAROMYCES CEREVISIAE

Amar J. S. Klar ¹, Jean McIndoo ¹, James B. Hicks ¹, and Jeffrey N. Strathern ¹

¹ Cold Spring Harbor Laboratory, P.O. Box 100, Cold Spring Harbor, N.Y. 11724

The HML and HMR loci carry unexpressed copies of MATa and MAT information, and a replica of that information is transposed to MAT during mating-type interchange in Saccharomyces yeasts. A negative control mechanism keeps silent the information located at the HML and HMR loci. We mapped these loci by constructing strains in which these loci are expressed. In these strains, the mating type of the segregants is dependent upon the allele at HML and HMR. This novel approach is independent of their switching function. HML is located on the left arm of chromosome III distal to his4 by about 26.8 centimorgans (cM). HMR maps on the right arm of the same chromosome distal to thr4 by about 39.8 cM and proximal to MAL2 by about 1.0 cM. The results allow the exact placement of these loci and are in accord with the observations made by Harashima and Oshima (1976).

This article has been cited by other articles:

				T. Srikantha, S. A. Lachke, and D. R. Soll Three Mating Type-Like Loci in Candida glabrata Eukaryot. Cell, April 1, 2003; 2(2): 328 - 340. [Abstract] [Full Text] [PDF]

				P. W. Sherwood The Yeast Genetics Course at Cold Spring Harbor Laboratory: Thirty Years and Counting Genetics, April 1, 2001; 157(4): 1399 - 1402. [Full Text]