Centrifugation, equilibrium density

A useful modification of equilibrium centrifugation involves spinning a concentrated salt solution in which the salt has a high molar mass, such as CsCl. A concentration gradient of the salt is generated, which in turn results in a density gradient in the solution. 

DNA samples purified by either stringent methods (equilibrium centrifugation in cesium chloride density gradients) or simple methods (organic extraction) have yielded reproducible RAPD patterns. However, in plants (e.g., members of the evening primrose family, Onagraceae) and... 

There are two principal methods that are suitable for quantitative determination of the constitutional heterogeneity fractionation and equilibrium sedimentation (equilibrium centrifugation) in a density gradient. In fractionation, the different solubilities of the polymers of various com-... 

For equilibrium centrifugation in a density gradient, a mixture of two solvents is prepared, one of which has a lower density than the other, and the density of any component in the polymer product lies between the densities of the two solvents. At equilibrium, a density gradient forms at... 

Illustration showing separation by equilibrium-density-gradient centrifugation. The homogeneous mixture in (a) separates into three bands (b) after applying centrifugal force. 

A phenol-degrading community was examined using phenol followed by analysis of the stable-isotope-labeled RNA by equilibrium density centrifugation, and complemented... 

In accordance with Equation (2.338) the determination of the figure of fiuid equilibrium is reduced to the following problem we have to find such a surface of the fluid, S(x,y,z), that its partial derivatives should be proportional to the corresponding components of the acting force. As we pointed out, when a fluid rotates uniformly around the same axis the total force can be represented as a sum of the attraction and centrifugal forces, and the former depends on the shape of the fluid mass in a rather complicated way. Besides, in the case of an inhomogeneous fluid the potential of the attraction field depends on the distribution of a density of a fiuid and for this reason this problem becomes even more complicated. 

An unknown event disturbed the equilibrium of the interstellar cloud, and it collapsed. This process may have been caused by shock waves from a supernova explosion, or by a density wave of a spiral arm of the galaxy. The gas molecules and the particles were compressed, and with increasing compression, both temperature and pressure increased. It is possible that the centrifugal forces due to the rotation of the system prevented a spherical contraction. The result was a relatively flat, rotating disc of matter, in the centre of which was the primeval sun. Analogues of the early solar system, i.e., protoplanetary discs, have been identified from the radiation emitted by T Tauri stars (Koerner, 1997). 

Isolation of Plasmid Enriched DNA. The three strains of B. megaterium were cultured in yeast-soy broth (4% Bacto-yeast extract and 1.6% Bacto-soytone from Difco Laboratories, Detroit, pH 7.2). Plasmid DNA from each strain was isolated and purified by cesium chloride-ethidium bromide equilibrium density centrifugation following the procedure of Carlton and Brown ( ). Subsequent gel electrophoresis (0.5% agarose) revealed the presence of some chromosomal DNA contamination. 

---