In all species except H. sapiens, the mean for the highest-expressed genes tended to be higher than that for the genes with the lowest expression level (Figure 6).Figure 6Comparison of the mean 5??? between genes with the highest 5% and the lowest 5% expression level in E. coli, S. cerevisiae, D. melanogaster, and H. sapiens.Since GC content, codon bias, and expression level all correlated with ,