GENETIC-ANALYSIS OF ANTIBODY RESPONSIVENESS TO SHEEP ERYTHROCYTES IN CROSSES BETWEEN LINES OF MICE SELECTED FOR HIGH OR LOW ANTIBODY-SYNTHESIS

  • 1 January 1979
    • journal article
    • research article
    • Vol. 36  (3) , 427-438
Abstract
Two selective breedings of mice for minimal or maximal agglutinin response to heterologous [sheep] erythrocytes were carried out (selection I and II). For both selections, the heritability was 0.18-0.36 and the number of relevant loci was from 7-13. The data of 10-20 generations at selection limit are available and large populations of interline hybrids F1, F2 and both backcrosses were analyzed, thus making this data definitive. The character high response was partially dominant in F1 hybrids of both selections, the degree of this incomplete dominance was 0.27 in selection I and 0.54 in selection II. In selection I, 38% of the F2 variance was due to genetic factors (VG) and 62% to environmental effects (VE). The partition of phenotypic variance of F2 and backcrosses into additive variance (VA) and dominance variance (VD) was made according to 3 methods and the mean results were: VA = 0.72 and VD = 0.05. The resulting mean heritability was 0.35 and the number of relevant loci was about 10. In selection II, 69% of the F2 variance was due to VG and 31% to VE. The 3 methods of variance calculation give somewhat discordant results. According to the more probable estimation VA = 0.95, the mean heritability was 0.23 and the number of loci was about 6. Crosses between homologous lines of the 2 selections indicated that the 2 high lines probably have identical homogeneous genetic constitution while the 2 low lines contain some different high effect loci.