Male rats weaned at 18 days of age were fed on a fat-deficient diet or a similar diet containing 5 per cent. maize oil. After 14 weeks 4 animals from each group were each given a single subcutaneous injection of 0.45 µC, of Na₂H³²PO₄ per g. bodyweight; 4 hr. later they were killed and the livers were removed for estimation of acid-soluble inorganic and organic P, phospholipin, phosphoprotein, deoxypentose nucleic acid (DNA) and pentose nucleic acid (PNA); fractions were assayed for radio-activity and, if appropriate, N content.

No difference in the uptake of ³²P into phosphoprotein, phospholipin, DNA or PNA was found between normal and fat-deficient rats. Since after 4 hr. the incorporation of ³²P into the acid-soluble P fractions had passed its maximum (Abst. 3258, Vol. 13), the lower specific activity of the acidsoluble organic P found in the livers of fat-deficient animals could not definitely be ascribed to a difference in the rate of incorporation of ³²P. The experiment was therefore repeated and the animals were killed 75 min. after injection of the isotope, to correspond with the rate of maximum incorporation of ³²P into the acid-soluble P fraction and to precede the time of maximum ³²P incorporation into the acid-soluble organic P fraction. No significant difference was observed between the specific activities of the acid-soluble inorganic P in the Livers of either group, but the specific activity of the acid-soluble organic P in the livers of the animals given the fat-deficient diet was significantly lower than that found in the rats fed normally.

Further studies in vitro on the liver tissue from both diet groups of rats showed no difference in anaerobic glycolysis, suggesting that the decreased uptake of ³²P into the acid-soluble organic P fraction in the livers of the fat-deficient animals is related to a dissociation of oxidation from phosphorylation accompanying the oxidation of intermediates in the Krebs cycle by the DPN-linked dehydrogenases.-G. A. Garton.