Variations of Ertyhrocyte Histone H1 Subtypes in a Muscovy Duck Population

Multiple non-allelic subtypes of histone H1 have been detected in higher organisms. These specific variants with distinct structural features may differ in their ability to condense chromatin and hence modify transcriptional activity. Such functional divergence between H1 subtypes has still not been established definitively, but it cannot be excluded that the role of a particular subtype may depend on its allelic complement. An allelic polymorphism of the erytrocyte histone H1 was found for three (H1.z, H1.a and H1.b) of six protein subtypes in different interbreed and interstrain hybrids of Pekin ducks. Here, we show various allelic complements of the erytrhrocyte histones H1.b and H1c' in another duck species, Muscovy ducks. Proteins were isolated by double extraction with perchloric acid from erythrocyte nuclei prepared in the presence of saponin. An electropheretical analysis was conducted, first on a acid-urea polyacrylamide gel, and next on a two-dimensional gel containing 0.1% SDS. Both distinct histone subtypes, H1.b and H1.c', migrated in the acid-urea gel as single bands giving three phenotypes of each protein, H1.b1, H1.b2, H1.b1b2 and H1.c'1, H1.c'2, H1.c'1c'2. The homozygous forms H1.b1, and H1.b2 or H1.c'1, and H1.c'2, migrated on these gels as sharp bands with different mobilities, while the heterozygous ones (H1.b1b2 or H1c'1c'2) constituted a diffused band with an intermediate location relative to the homozygous forms. On the two-dimensional acrylamide gel, the proteins belonging to distinct homozygotes were visualised as single spots differing in location relative to the adjacent proteins (H1.b relative to H1.a and H1.c' relative to H1.d), while the heterozygous proteins appeared as a double spot. These electrophoretic data seems to indicate that proteins originating from distinguished homozygotes may differ in their net charges and show similar apparent molecular masses. In the screened duck population, we observed that the individuals with histone H1.b2 (phenotype b2) and those with H1.c'1 (phenotype c'1) were the most common, while those with histone H1.b1 (phenotype b1) and histone H1.c'2 (phenotype c'2) were quite rare. Unfortunately, we were unable to analyse the offspring of the tested population, but, based on our earlier findings, we assume that the occurence of such variations among histone H1 subtypes is determined genetically.