Cytoplasmic effects of cortisol in liver.

1. The time-course of the induction by cortisol of tryptophan pyrrolase in mouse liver was established. 2.

The synthesis of nicotinamide-adenine dinucleotide and poly (adenosine diphosphate ribose) in various classes of rat liver nuclei.

1. The activities of NMN adenylyltransferase and an enzyme that synthesizes poly (ADP-ribose) from NAD were investigated in the various classes of rat liver nuclei fractionated by zonal centrifugation. 2.

A study of nucleated erythrocytes by density-gradient centrifugation in a zonal rotor.

1. Several substances of high molecular weight were examined for their suitability as suspension media in the formation of density gradients for the zonal centrifugation of avian erythrocytes. None proved satisfactory.

The fractionation of nuclei from mammalian cells by zonal centrifugation.

1. Purified liver nuclei from adult rats separate into two main zones when centrifuged in the slow-speed zonal rotor. One zone contains diploid nuclei, the other tetraploid.