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Unformatted text preview: pe of signal transduction pathway dissected in the New genome-wide assays have identiﬁed additional genes
that are turned on in response to pheromones. Researchers
used DNA arrays (see Chapter 10 of the main textbook) to
assay simultaneously the abundance of cDNA’s corresponding to virtually all cellular mRNAs in cells before and after treatment with pheromone (Fig. A.16a). The arrays
contain oligonucleotides corresponding to all the annotated
ORFs known to code for yeast proteins (about 6000 of
them). In a representative experiment, cDNA pools from
two sets of a cells—one treated with a pheromone, the
other untreated—were differentially labeled with the ﬂuorescent dyes Cy3 (green) or Cy5 (red) and then mixed and
probed by competitive hybridization to the genomic arrays.
Changes in the abundance of an individual mRNA produces a spot that ﬂuoresces red or green, depending on
whether the corresponding mRNA increases or decreases
in abundance in response to -pheromone treatment. A genomic view of the data can be obtained b...
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- Spring '08