Venn diagram evaluating the prediction of highly expressed genes (tCAI and dCAI) by comparison with microarray gene expression data (Expr). The overlap between genes with top 10% tCAI, dCAI, and Expr values are pictured as overlapping circles, in which the number of genes found by either method is given. The organisms are sorted in order of decreasing correlation (rho) between tCAI and dCAI values based on all genes in each organism. For organisms with high correlation (high rho) between tCAI and dCAI values, most genes are predicted as highly expressed by both measures. Moreover, these predictions overlap significantly with genes found to be highly expressed experimentally by microarrays. For organisms with low correlation (low rho) between tCAI and dCAI values, few genes are predicted as highly expressed by both measures. Here, more genes predicted as highly expressed by tCAI are found to be highly expressed by microarrays than for dCAI. dCAI, dominant codon adaptation index; tCAI, translational codon adaptation index.