Figure 1.

Scatter plots of RGF versus RSCU. The RGF of tRNA genes is the observed frequency of an isoacceptor tRNA gene in Gallus gallus genome divided by the frequency expected if all isoacceptor tRNA genes for that amino acid were equally frequent in the genome. The RSCU is the observed frequency of a codon divided by the frequency expected if all synonyms for that amino acid were used equally. (a) RSCU was measured in the highly expressed genes and (b) RSCU was measured in the lowly expressed genes.