AN ANALYSIS OF AN APPARENT SEX DIFFERENCE IN THE DESOXYRIBONUCLEIC ACID CONTENT OF RAT LIVER
ABSTRACT Using the extraction procedure of Schmidt & Thannhauser (1945) and the indole reaction for DNA according to Ceriotti (1952), the DNA content of female rat liver was about one and a half times that of male liver. Castration of male rats, with or without administration of testosterone propionate, had no effect on the liver DNA content. Spaying of female rats (5–6 weeks of age) caused a decrease of the liver DNA content. Substitution with oestradiol benzoate restored the amount of DNA. No significant sex difference was observed in the DNA content of either rat brain, kidney, spleen and thymus, or mouse liver. Dische's diphenylamine reaction showed no significant sex difference in the rat liver DNA content. It was concluded that rat liver may contain a substance which is controlled by oestrogens and which interferes with the indole reaction. The interfering factor is present in the protein fraction of the liver extract. The possible nature of this interfering substance is discussed.