Abstract #54

Gene-environment interaction in yeast: the genetic and molecular basis for strain-specific response to condition. Erin Smith^1,2, Leonid Kruglyak¹. 1) Dept Ecol & Evol Biol, Princeton Univ, Princeton, NJ; 2) Molecular and Cellular Biology, University of Washington, Seattle, WA.
   Organisms are primed to respond to their environments, yet the particular behavior of individual strains can vary greatly. The precise molecular mechanisms involved in these gene-environment interactions, however, are rarely delineated. In order to address this, we are studying the genetic regulation of transcriptional phenotypes in the yeast Saccharomyces cerevisae grown in different conditions. A set of 114 segregants from a cross between a lab (BY4716, isogenic to S288c) and a vineyard strain (RM11-1a) were grown in batch culture with synthetic medium (YNB) and either 2% glucose or 1% ethanol. Transcriptional phenotypes were measured by expression microarrays, and genetic regulators of the level of each transcript were determined by performing linkage analysis in each condition separately. In order to assess the extent of gene-environment interaction, data from a single segregant were paired and linkage analysis was performed on the difference between the conditions. Gene-environment interactions were very common, affecting approximately one quarter of all transcripts, as compared to about half of all transcripts showing linkage to at least one locus within a condition. Loci that showed gene-environment interaction were less likely to be located near the open reading frame of the transcript in question, suggesting that promoter and other cis-linked polymorphisms are less environmentally dependent than those in trans acting pathways. Coregulation of large groups of transcripts was also variable across conditions, and it was common for a group to regulated by one locus in one condition, yet regulated by another locus or loci in the other condition. We are currently performing allele-exchange experiments to determine the specific polymorphisms responsible for a set of these environmentally dependent phenotypes.

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