Codon usage patterns in the Atlantic salmon Salmo salar L.

Synonymous codon usage patterns were investigated for the teleost fish Salmo salar L. Correspondence analysis was used to identify the single major cause of variation in codon usage. The most important trend is from nearly random use of all synonymous codons, in genes with a moderate G + C content, to selective use of a smaller subset of codons in genes with a relatively high G + C content. The identity of the central nucleotide of the triplet also has a bearing on the frequency with which some codons are used. There does not appear to be a mutational pressure-translational selection balance in operation. The most abundant codons are identified for all the genes and also for the most biased and the least biased genes.