Effect of low lysine diet on rat liver nuclear metabolism.

Prolonged dietary lysine deficiency induced by feeding male weanling rats a diet low in lysine for 6 weeks resulted in substantial impairment of growth as compared with control rats and in alterations in the morphology of the nucleus of hepatocytes. Electronmicrographs of liver nuclei from lysine deficient rats showed an increased incidence of binucleated cells, reduction in numbers of nucleoli, changes in the position and size of nucleoli within the nucleus and altered patterns of chromatin aggregation in lysine deficient rats. Mass ratios of nonhistone proteins to DNA in liver chromatin from lysine deficient rats were higher than those of controls and electrophoretic patterns of chromatin nonhistone proteins were altered. In particular, one high molecular weight fraction of these proteins showing the same mobility as myosin was substantially enriched. The histone: DNA ratio and histone electrophoretic patterns, however, appeared to be unchanged. Incorporation of [3H] thymidine into DNA was increased, but the nuclear content of DNA was unchanged in lysine deficient animals.