Patterns of synonymous codon usage for Hsp60 genes
To understand the peculiarities of codon usage, it is necessary to assess not only the degree of codon usage bias, but also the representation of synonymous codons in a gene, or, in other words, the patterns of synonymous codon usage. The approach widely used for this purpose is the calculation of synonymous codon usage bias, reflecting the peculiarities of amino acid coding, when some codons in a gene are used more often than other synonymous codons68. Under the influence of the mutational pressure and natural selection69, the representation of various codons in a gene plays an important role in the processes of its transcription70 and translation71. Determination of patterns of synonymous codon usage is necessary for understanding the features of gene/genome evolution. Thus, the relative synonymous codon usage (RSCU) of 64 codons in the Hsp60 genes was calculated (Figure 11; Supplementary, RSCU).