Effect of vitamin B12 deficiency and fasting on the incorporation of P32 into nucleic acids and phospholipides of infant rats.

Histochemical studies have shown a decreased concentration of cytoplasmic pentose nucleic acid1 in the liver (l-4)) pancreas (2), spinal cord (3), and cervical ganglia (3) of vitamin Blz-deficient rats. The concentration of both PNA and DNA per gm. of tissue was decreased in livers from weanling rats fed a diet containing iodinated casein, but the amount per cell was unchanged (5, 6). Comparison of new born rats from control and vitamin Blz-depleted dams (7) showed no difference in the DNA or PNA concentration per gm. of liver tissue, but the deficient livers contained slightly less PNA per cell. Brain tissue from the deficient offspring had more cells and more DNA per gm. of tissue, but the amount of DNA per nucleus was unchanged. The amount of PNA per brain cell was less in the deficient animals. Recent observations on growing rats produced by vitamin Blz-depleted dams (8) confirmed earlier results that the concentration of DNA and PNA per gm. of liver is decreased and demonstrated a decreased rate of PNA and DNA regeneration after partial hepatectomy. From carcass analyses it has been postulated (9) that vitamin B,z plays a role in carbohydrate and fat metabolism. An extension of this study (10) showed that a deficiency of vitamin B,z results in a derangement of carbohydrate utilization and a decreased phospholipide content of blood and tissues. In order to gain more insight into the effect of vitamin Blz on nucleic acid and phospholipide metabolism, a study was made of P32 incorporation into brain and liver tissue of new born rats from vitamin Blz-depleted and control dams. The specific activity of the acid-soluble phosphorus de-