Comparative studies of RNA synthesis and polyribosome metabolism in normal (RFL) and transformed (RFL-T) cells under serum starvation show that their growth is more or less dependent upon serum factor. By limiting serum in the medium, 80 to 90% of RNA or protein synthesis is inhibited in RFL cells, while in RFL-T cells macromolecular synthesis proceeds at one-third to one-fourth the rate of con...

A method that gives high recovery of deoxyribonucleic acid (DNA) from crude bacterial lysates using ethidium bromide-cesium chloride density gradient centrifugation is presented. After Pronase digestion and shearing of the lysate, essentially 100% recovery of chromosomal DNA and a reproducible recovery of covalently closed circular (CCC) plasmid DNA is obtained for a specific plasmid in a given...

1. Conditions have been established for the estimation of molecular weights of proteins by analytical gel filtration and sucrose-density-gradient centrifugation in 2.5M-potassium chloride-l M-sodium chloride; Halobacterium cutirubrum polynucleotide phosphorylase, DNA-dependent RNA polymerase and RNA-dependent RNA polymerase have been studied by these methods. 2. The RNA-dependent polymerase has...

Incomplete particles arising during productive growth of adenovirus were separated from infectious particles by density gradient centrifugation. The DNA contained in particles of low density was characterized by restriction enzyme analysis and by electron microscopy and heteroduplexing techniques. The DNA is heterogeneous in length, ranging in size from 15% of the normal genome to full length. ...

A new type of biological particle, isolated from the marine dinoflagellate Gonyaulax polyedra, has been partially purified and characterized. When the pH is lowered, the particle emits light in vitro in a fashion closely mimicking the flash of the living cell, and it is referred to as a scintillon (flashing unit). Scintillons are obtained by breaking the cells in buffer at pH 8.2 and purifying ...

The purification of human neutrophils for in vitro studies is challenging as they are easily activated through ex vivo manipulations. The technique of erythrocyte sedimentation combined with density gradient centrifugation remains widely practiced and was the subject of this study. Since in the sedimentation step the leukocytes are incubated with dextran, we have raised the likelihood that cell...

A direct fluorescent-antibody test for smallpox is described which utilizes a conjugated antivaccinia serum that was purified by diethylaminoethyl fractionation. The purity of the conjugate was analyzed by density gradient centrifugation, and specific staining of smallpox and nonsmallpox specimens was measured quantitatively by a photovoltmeter. Variola elementary bodies were identified in all ...

A quick density gradient-banding subfractionation method has been developed for d < 1.063 g/ml lipoproteins. Up to 324 ml of plasma can be resolved into five distinct layers by a single ultracentrifugation. The separation was achieved with a discontinuous density gradient formed between plasma and a layer of NaCl solution of d 1.080 g/ml in an angle-head rotor during centrifugation at 45,000 rp...