The goals of this project are to characterize the mechanisms by which ploidy is limited in Saccharomyces cerevisiae. Yeast with ploidies as high as 6n have been easily generated, however, it has not been possible using low-resolution techniques to generate viable yeast with a ploidy above 6n (greater than 6n). Limitations in polyploidy are also seen in other eukarytoic cells in a cell-type specific manner. Many liver hepatocytes are 4n, but, the number that achieve a ploidy of 8n are limited. In addition, the proliferative activity of rat liver carcinoma cells decreases in an inverse proportion to their ploidy. In contrast, megakaryocytes can reach as high as 64n.
The specific aims of this research proposal are the following: (1) Accurately identify the limits on increasing polyploidy in yeast. Complementary markers will be used to select for viable 8n polyploids from crosses using large numbers of parental cells. The frequency with which 8n polyploids arise (if 8n polyploidy is possible in these strains) will be determined. The phenotypes of isolated 8n yeast will be carefully examined. (2) Identify genes that are involved in limiting polyploidy. Seventeen genes are known to have ploidy-regulated expression. The role that the altered expression of each may play in the prevention of viable greater than 6n strains will be analyzed by overexpressing those that are repressed in polyploids and disrupting those that are induced. (3) Identify differences in the patterns of genes expressed during conjugation when comparing n x n and polyploid crosses. Whole genome mRNA expression microarrays will be used to analyze yeast in n x n, 2n x 2n, and 4n x 4n crosses. Genes that are differentially expressed between these crosses will be identified and examined further.

Agency
National Institute of Health (NIH)
Institute
National Institute of General Medical Sciences (NIGMS)
Type
Postdoctoral Individual National Research Service Award (F32)
Project #
5F32GM020565-02
Application #
6385199
Study Section
Biological Sciences 2 (BIOL)
Program Officer
Wolfe, Paul B
Project Start
2000-07-01
Project End
Budget Start
2001-07-01
Budget End
2002-06-30
Support Year
2
Fiscal Year
2001
Total Cost
$40,196
Indirect Cost
Name
Whitehead Institute for Biomedical Research
Department
Type
DUNS #
076580745
City
Cambridge
State
MA
Country
United States
Zip Code
02142
Reynolds, Todd B; Jansen, An; Peng, Xin et al. (2008) Mat formation in Saccharomyces cerevisiae requires nutrient and pH gradients. Eukaryot Cell 7:122-30
Reynolds, Todd B (2006) The Opi1p transcription factor affects expression of FLO11, mat formation, and invasive growth in Saccharomyces cerevisiae. Eukaryot Cell 5:1266-75
Reynolds, T B; Fink, G R (2001) Bakers' yeast, a model for fungal biofilm formation. Science 291:878-81