Fig. 4.

—Proportions of epigenetic marks in the first introns of genes classified by gene essentiality. Genes are classified into essential genes and nonessential genes by gene essentiality (see Materials and Methods). The same procedures used for figure 3 were applied in this analysis, where we grouped genes by the numbers of introns in the genes from G1 to G20 in the same way as for figure 3. For each group in each class, we estimated the proportions of chromatin marks as described in the figure 3 legend.