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Quantitative analysis of wine yeast gene expression profiles under winemaking conditions. Cristian Varela1*, Javier Cárdenas1, Francisco Melo2, Eduardo Agosin1§ |
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Wine fermentation is a dynamic and complex process in which the yeast cell is subjected to multiple stress conditions. A successful adaptation involves changes in gene expression profiles where a large number of genes are up- or down-regulated. Functional genomic approaches are commonly used to obtain global gene expression profiles, thereby providing a comprehensive view of yeast physiology. We used Serial Analysis of Gene Expression (SAGE) to quantify gene expression profiles in an industrial strain of Saccharomyces cerevisiae under winemaking conditions. The transcriptome of wine yeast was analysed at three stages during the fermentation process, mid-exponential phase, and early- and late-stationary phases. Upon correlation with the yeast genome, we found three classes of transcripts: (i) sequences that corresponded to Open Reading Frames (ORFs); (ii) expressed sequences from intergenic regions; and (iii) messengers that did not match the published reference yeast genome. About 10% of transcripts matched non-annotated ORF regions within the yeast genome and could correspond to small novel genes originally omitted in the first gene annotation effort. Up to 22% of transcripts, particularly at late-stationary phase, did not match any known location within the genome. As the available reference yeast genome was obtained from a laboratory strain, these expressed sequences could represent genes only expressed by an industrial yeast strain. Further studies are necessary to identify the role of these potential genes during wine fermentation.
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1Departamento de Ingeniería Química y Bioprocesos, Facultad de Ingeniería. 2Departamento de Genética Molecular y Microbiología, Facultad de Ciencias Biológicas. Pontificia Universidad Católica de Chile, Santiago, Chile.
* current address: The Australian Wine Research Institute, PO Box 197, Glen Osmond (Adelaide) SA 5064, Australia
§To whom correspondence should be addressed at: E-mail: agosin@ing.puc.cl |