[Effect of thyroxine on the protein makeup of condensed and diffuse chromatin from the liver of rats of different ages].

Contant composition of histones and marked alterations in the non-histone proteins were found in condensed and diffuse chtomatins of rat liver tissue during postnatal ontogenesis both in normal state and in treatment with thyroxine. Thyroxine affected the ratio histones (non-histone proteins in condensed chromatin of animals of the all age groups studied, except the old rats, in which the ration did not differ from the control values. After thyroxine administration the ratio histones) non-histone proteins was increased in diffuse chromatin of predolescent rats; the ratio was slightly decreased in diffuse chromatin of puberal rats and it was remarkably unaltered in the chromatin of adult and t was remarkably unaltered in the chromatin of adult an old animals. Considering the fact that thyroxine increased in the condensed chromatin the content of non-histone proteins and decreased the content of histones, the data obtained suggest that the hormone caused a shift in the ratio condensed/diffuse chromatin towards the increase in content of the diffuse chromatin.