Summary of microarray data

Fig. 17. This is a modified version of Fig. 1 from Spellman et al. (1998) Mol. Biol. Cell 9:3273-3297. Cells were synchronized by four methods (alpha-factor block and release, cdc15 block and release, cdc28 block and release, and centrifugal elutriation). RNA was isolated from cells at various times during synchronous growth and converted to fluorescently tagged cDNA. Control cDNA, labeled with a different fluorescent tag, was prepared from unsynchronized cultures of the same cells. The control and experimental cDNA preparations were mixed and hybridized to cDNA microarrays representing nearly all yeast genes. The results were quantified and analyzed. Of 6200 genes, 800 were found whose expression levels clearly varied in a cell-cycle-specific fashion. Results for those 800 genes are summarized in this figure. Each gene is represented by a row of results. Two cell cycles are shown for the block and release methods, and one cycle is shown for centrifugal elutriation (which does not produce as good synchrony but is more natural). The genes are arranged in groups (shown in the colored bar on the right), based on the position in the cell cycle where their expression is maximal. The same correlation between colors and cell cycle phases is employed in the horizontal bars at the top of the figure. It is evident that dividing the genes into groups is somewhat arbitrary, because there appears to be a continual variation in time of maximal expression as one moves from the top of the diagram to the bottom. If you want to know the identities of the 800 cell-cycle-regulated genes, look at the original paper or visit the associated web site (http://cellcycle-www.stanford.edu).