to examine gojobori and nei 's hypothesis that the immunoglobulin heavy-chain variable-region ( vh ) genes in mammals are subject to diversity-enhancing selection , we studied the rates of synonymous and nonsynonymous nucleotide substitution in the complementarity-determining regions ( cdrs ) and in the framework regions ( frs ) of mouse and human vh genes .
C0877857
immunoglobulin
C0021024
complementarity-determining regions