Effect of Divergent Selection for IgM and IgG Levels on the Change in Gene Frequency of Blood Group Systems and Blood Protein Loci in Chickens

Abstract

To examine the effect of divergent selection for serum immunoglobulin M (IgM) and G (IgG) levels two pairs of chicken lines of four generations were selected. The base population from which the experiment was started composed of six lines. Serum IgM and IgG levels and changes in gene frequencies of blood groups and blood protein loci were monitored for all individuals in each generation. Selection was effective (P<0.01) in changing the serum IgM and IgG levels. The differences between the high immunoglobulin M (HIM) and low immunoglobulin M (LIM) lines as well as high immunoglobulin G (HIG) and low immunoglobulin G (LIG) lines became gradually larger during the process of selection. A remarkable effect of selection on the changes of gene frequencies of blood proteins was not observed. In the HIM line, gene frequency of the BA allele increased and that of the BG and BN alleles decreased over the course of selection. In the LIM line, gene frequency of the BA allele decreased and that of BG and BN alleles increased during the selection. Similar tendency was also observed for the BA, BG, and BN alleles of HIG and LIG lines. This contrasting change in gene frequency of the BA, BG, and BN alleles in the two selected lines suggest that the B blood group alleles may be involved in IgM and IgG production.