Comparative gene expression between two yeast species

The Ascomycete yeasts present one of the most promising systems for comparative functional genomics. Fungi have been densely sampled by a number of sequencing projects [1], covering an enormous range of divergence. Genome sequence analyses of the Saccharomyces yeasts and related species have been used to establish the history of gene duplication [2-6], conservation at binding sites [7,8], and co-evolution of binding sites with regulators [9]. Thus, a range of evolutionary phenomena can be studied in these species based on their genomic sequence. However, sequence conservation is not always completely predictive of functional conservation. As just one example, we recently reported that only a subset of conserved promoter motifs actually drive periodic gene expression over the cell cycle in two closely related species [10].