The transcription response of spores to different components of the medium. (a) The experimental design. Mature spores (prepared from strain DS1) were incubated in rich medium (YPD) that induces spore germination (Figure 2a) or in either component of the medium (glucose alone or 'nitrogen' - synthetic minimal medium without glucose). Each circle represents a time point at which genome-wide gene expression was monitored; RNA was extracted, labeled and hybridized to micorarray complementary to all (approximately 6,200) yeast ORFs. The reference RNA was a mixture of RNA from Mata and Matα log phase cells. (b) The matrix of pairwise correlations describing the similarity between gene expression of all approximately 6,200 genes in the yeast genome for each pair of time points following incubation of spores in glucose, 'nitrogen' or YPD media. Every point represents the correlation between the transcription patterns of two time points. *Correlations are color-coded according to the bar shown. (c-e) Enlargements of the parts marked in circles in the correlation matrix presented in (b).