Chromatin was prepared from isolated nuclei of proliferating and differentiated cultures of C1300 mouse neuroblastoma cells. Differentiation was induced by serum withdrawal or treatment with dibutyryl cyclic AMP. The ability to support DNA-dependent RNA synthesis when assayed in a cell-free system is three times greater for chromatin from proliferating cells. Histones isolated from proliferatin...

Despite growing concern about electromagnetic radiation, the interaction between 50- to 60-Hz fields and biological structures remains obscure. Epidemiological studies have failed to prove a significantly correlation between exposure to radiation fields and particular pathologies. We demonstrate that a 50- to 60-Hz magnetic field interacts with cell differentiation through two opposing mechanis...

Photoactivation allows one to pulse-label molecules and obtain quantitative data about their behavior. We have devised a new modeling-based analysis for photoactivatable actin experiments that simultaneously measures properties of monomeric and filamentous actin in a three-dimensional cellular environment. We use this method to determine differences in the dynamic behavior of β- and γ-actin iso...

The distribution of tubulin in soluble, reversibly stabilized (assembled) and insoluble forms has been determined in neuroblastoma cells undergoing microtubule-dependent neurite elongation. Procedures were developed to obtain reproducible tubulin fractions and to assay total tubulin. Radioimmunoassays showed that both differentiated and nondifferentiated cell contained approximately 4 pg of tub...