Tissue specificity and age changes for the pattern of the H1 group of histones in chromatin from mouse tissues.

Polyacrylamide gel electrophoresis of the H1 group of histones extracted from different rat and mouse tissues shows a different pattern of fraction (H1, H1 degrees, H1 degrees met) when the two species are compared. Different tissues of each species also have a different pattern of H1 histone fraction and subfraction. However, the age-associated changes of mouse H1 histones from liver and spleen chromatin show the same type of alteration of fraction ratios which had been demonstrated in our earlier research with rat tissues. In both species there is a relative increase of the F1 degree and F1 degree met fractions in tissues from old animals. The presence of the F1 degree fraction in only non-dividing cells suggests that there may be an age-specific type of chromatin condensation.