1. Rat liver nuclei were isolated from normal rats and rats fasted for 36 hours by a slight modification of the Behrens technique. 2. The nucleus of the rat liver cell contains two types of alkaline phosphatase. This confirms the previous findings on rat liver nuclei isolated in aqueous media. 3. The one type of alkaline phosphatase is not activated by magnesium ions, and this enzyme is very st...

Recombinant plasmids with inserts complementary to the mRNA for carbamyl phosphate synthetase I were identified from a rat liver cDNA library by hybrid-selected mRNA translation. Four clones, the largest being 3100 base pairs, were identified for the rat liver enzyme. Using the rat liver cDNA as a probe, two homologous recombinant plasmids of approximately 1200 base pairs in length were isolate...