Difference in relative synonymous codon usage (RSCU) across codons between genes with high and low gene expression. Codons are sorted after average ΔRSCU. The right-most column indicate codons with significantly increased usage in high-expression genes as determined by a t-test. Each * denotes a species for which the t-test was significant, in the same order as they are listed in the Figure. Codons above the horizontal dotted lines were used to designed optimal codons and were used to calculate frequencies of optimal codon usage (F
) in all species. The colors in the figure indicate the gradient of ΔRSCU values, from the most positive(orange) to the most negative (green).