DNA in cells exhibits a supercoiled state in which the double helix is additionally twisted to form extended intertwined loops called plectonemes. Although supercoiling is vital to many cellular processes, its dynamics remain elusive. In this work, we directly visualize the dynamics of individual plectonemes. We observe that multiple plectonemes can be present and that their number depends on a...

A procedure has been developed for the quantitative determination of the extraetable proteins of the nit heart. Utilizing extraction with a sucrose-versene solution and employing differential centrifugation, followed by extraction with a phosphate-pyrophosphate buffer, low-ionic-strength extractives, a mitochondrial fraction, and high-ionic-strength extractives have been obtained. Electrophoret...

It is known since the early days of molecular biology that proteins locate their specific targets on DNA up to two orders of magnitude faster than the Smoluchowski 3D diffusion rate. It was the idea due to Delbrück that they are non-specifically adsorbed on DNA, and sliding along DNA provides for the faster 1D search. Surprisingly, the role of DNA conformation was never considered in this conte...

The observation that “old” water dominates storm runoff suggests that release of low-solute water from soils rather than rainwater must cause storm runoff dilution. This inference is supported by sprinkling experiments in an 860-m catchment in the Oregon Coast Range, in which .200 mm of both high and low ionic strength precipitation produced similar concentration-discharge trends. Rainwater che...

The kinetics of Mn(VII) oxidation of lysine in moderately sulfuric acid solutions was studiedspectrophotometrically in the presence and absence of Mn(II) as catalyst. The reaction was arrangedto be under pseudo first-order condition with respect to Mn(VII). The results showed that the pseudofirst-order rate constant increases with increasing [H2SO4], [(Mn)II], and [lysine]. The dependence ofthe...

A systematic approach to the in vitro measurement of HNA-dependent RNA polymerase activities in nuclei from immature rat uterus has been undertaken in order to evaluate the early effects of estradiol. The experimental conditions include excess of nucleoside .i’-triphosphate and short time assays (6 min) at low temperature (25”) in order to obtain the maximal velocity of the reaction and to mini...

We present a numerical and experimental study of the effects of ionic strength on electrophoretic focusing and separations. We review the development of ionic strength models for electrophoretic mobility and chemical activity and highlight their differences in the context of electrophoretic separation and focusing simulations. We couple a fast numerical solver for electrophoretic transport with...

The influence of varying the ionic strength of the bathing solution on the contraction of chemically skinned frog atrial muscle fibers was studied. The rate of tension development activated by calcium slows as the ionic strength is elevated. The size of caffeine contracture, however, was larger in the fiber preloaded with calcium at a higher ionic strength. There was a decrease in the maintaine...

A systematic approach to the in vitro measurement of HNA-dependent RNA polymerase activities in nuclei from immature rat uterus has been undertaken in order to evaluate the early effects of estradiol. The experimental conditions include excess of nucleoside .i’-triphosphate and short time assays (6 min) at low temperature (25”) in order to obtain the maximal velocity of the reaction and to mini...

The Rb+(K+) efflux of erythrocytes from six mammalian species was investigated in solutions of physiological and low ionic strength. A species dependent increase of the Rb+(K+) efflux in low ionic strength solution could be observed. The rate constant of Rb+(K+) efflux of erythrocytes in physiological ionic strength solution correlates with the content of arachidonic acid of the membrane phosph...