Transcriptional analysis of coexisting genomes in interspecific hybrids of Saccharomyces cerevisiae and Saccharomyces bayanus.
Duccio Cavalieri (1), Julia Oh (2), Christine Queitsch (3), Christian Landry (4)
(1) Department of Pharmacology, University of Florence, Viale Pieraccini 6, Florence, 50139, Italy; (2) Department of Biological Sciences, Stanford University, Stanford CA, 94305 USA; (3) Bauer Center for Genomics Research, Harvard University, 7 Divinity Avenue, Cambridge, MA 02138 USA; (4) Organismic and Evolutionary Biology, Harvard University, 16 Divinity Avenue, Cambridge, MA 02138 USA
Throughout evolutionary history, hybridization of separately evolving genomes has given rise to novel species with often greatly altered physiological responses to environmental conditions. Studies on cis-trans regulation of transcription in interspecific hybrids has the potential to shed new light on how the evolution of transcriptional regulation is connected to the appearance of novel phenotypes in diverged species. Here we study the integration of the independently evolving transcriptional networks of two closely related yeast species, Saccharomyces cerevisiae and Saccharomyces bayanus and their F1 hybrid. Both yeasts are sequenced and their genomes are divergent enough to allow the design of species-specific microarray elements. In order to assess the relative contribution of the S.c. and S.b. alleles to the transcriptional phenotype of hybrid cells upon temperature shift we have used S. cerevisiae ORF microarrays and designed 70 base pair oligonucleotides that enable to examine allele-specific expression for a subset of the homologous genes. Our results reveal novel transcriptional profiles in hybrid cells, demonstrating that the interaction of the two genomes opens a novel transcriptional landscape, particularly altering the regulation of chaperone and ribosome biogenesis genes in response to growth in the cold. The results obtained allow to reconstruct the relative contribution of the two separate genomes to the regulatory network underlying the hybrid phenotype.