Coexpression of species-specific histone H1 and H2B genes in mouse-rat hybrid cells

Five different clones of somatic hybrid cell lines between mouse and rat cells were examined for the expression of species-specific histone H1 and H2B subtypes. It was found that one hybrid (140-3) contained only mouse specific histones and the other four clones had both mouse and rat specific histones in various ratios. In three cases (141-B, NBr10A, NBr20A), the relative amount of mouse and rat specific histones was correlated with the karyotype of the hybrids. However, this was not true in one case (NG108-15). The results indicate that a single mammalian hybrid clone can express both parental types of histones, and the histone expression in these hybrids is not regulated by an allelic exclusion but may be expressed codominantly by gene dosage.