Comparative rates of synthesis in diphosphopyridine nucleotide by normal and tumour tissue from mouse mammary gland: studies with isolated nuclei

Abstract

Nuclei were isolated from lactating and non-lactating mammary glands from strains of mice with high (C3H) and low (NZ) tumor incidence, and from mammary-gland carcinomata from C3H mice. Tissues were compared on the basis of the rates of synthesis of diphosphopyridine nucleotide (DPN) from adenosine triphosphate (ATP) and nicotinamide mononucleotide by the isolated nuclei. The mean rates of synthesis (per 109 nuclei) by tumor was about one-third that of gland from pregnant, non-lactating mice and about one-fifth that of lactating gland tissue. The results were very consistent, and in all cases the differences between means were statistically highly significant. There was no statistical difference between the mean rates for lactating glands from C3H and NZ mice. The mean rates of synthesis (per 109 nuclei) for nuclei isolated from livers of fetal, young and adult mice were very much less than that of the adult mice. The significance of these findings is discussed in the light of previous work relating to a possible lesion in tumor tissue involving enzyme systems linked with DPN.