A shift in erythrocyte histone H1 complement following selection in quail (Coturnix japonica)

This work was aimed at comparing distribution of isoforms for polymorphic histone H1 variants H1.b and H1.z and variably abundant histone H1.d subtype between quail (Coturnix japonica) population selected for a high egg yolk cholesterol content and the control birds. The isoforms of histone H1.b (H1.b1, H1.b2) and histone H1.z (H1.z1, H1.z2) differed in their apparent molecular weights judging from their differential migration rates in one- and two-dimensional SDS-polyacrylamide gels. Stained histone H1.d bands and spots in one-dimensional acetic acid-urea and two-dimensional SDS-polyacrylamide gel patterns, respectively, exhibited differential intensities among quail individuals. Histone H1.d phenotypes with high (dh), intermediate (dhdl), and low (dl) amount of protein, displaying a small within-phenotype variability of the protein band intensities (coefficients of band variation below a threshold value of 0.25) were shown to be inherited in a Mendelian fashion with two alleles at a locus contributing to the band intensity. The frequencies of histone H1 alleles at loci H1.b (χ2 = 13.32, d.f. = 1, P < 0.001), H1.z (χ2 = 21.84, d.f. = 1, P < 0.001), and H1.d (χ2 = 8.98, d.f. = 1, P < 0.01) were found to be statistically significant among the control and selected population. In general, a moderate degree of genetic divergence (FST equal to 0.07 and 0.1 at loci H1.b and H1.z, respectively) was observed among the control and selected quail populations. Selection may directly or indirectly affect the complement of H1 histones because of their presumably differential interactions with DNA and/or DNA-associated proteins resulting in alterations in the chromatin function.