Electrophoretic Mobility of Mycobacterium avium Complex Organisms

The electrophoretic mobilities (EPMs) of 30 Mycobacterium avium complex organisms were measured. The EPMs of 15 clinical isolates ranged from -1.9 to -5.0 microM cm V(-1) s(-1), and the EPMs of 15 environmental isolates ranged from -1.9 to -4.6 microM cm V(-1) s(-1) at pH 7.     

Electrophoretic Mobility of Mycobacterium avium Complex Organisms

The electrophoretic mobilities (EPMs) of 30 Mycobacterium avium complex organisms were measured. The EPMs of 15 clinical isolates ranged from −1.9 to −5.0 μm cm V⁻¹ s⁻¹, and the EPMs of 15 environmental isolates ranged from −1.9 to −4.6 μm cm V⁻¹ s⁻¹ at pH 7.     

Cellular Electrophoretic Mobility and the Mitotic Cycle

The electrophoretic mobility of RPMI No. 41 cells grown in suspension, parasynchronized by double thymidine blocking and cold shock, is reported. No. 41 cells have a higher electrophoretic mobility during the mitotic peak phase than at other times in the mitotic cycle. Treatment of parasynchronous cells by neuraminidase reduces the mobility to the same value irrespective of the stage of the cells in the mitotic cycle. The higher electrophoretic mobility of cells in mitotic peak phase is probably due to a higher surface charge density at this time, possibly caused by a higher concentration of ionized neuraminic acid carboxyl groups at the hydrodynamic shear layer. The mobility of nonsynchronous rapidly and slowly growing cells differs; neuraminidase reduces their mobility by proportionately similar amounts. The results suggest that the differences in mobility between rapidly and slowly growing cells cannot be accounted for exclusively by differences in the amount of neuraminic acid groups at the shear layer.     

Dependence of the Electrophoretic Mobility of DNA in Gels on Field Intermittency

Abstract

The electrophoretic mobility of double helical DNA in agarose and Polyacrylamide gels increases as a function of time after the electric field is applied to the gel and decreases after the field is terminated. The changes are large for long (more than 10 kb) molecules. The effects of other variables are indicated.     

Electrophoretic Mobility of DNA in Solutions of High Ionic Strength

The free-solution mobilities of small single-stranded DNA (ssDNA) and double-stranded DNA (dsDNA) have been measured by capillary electrophoresis in solutions containing 0.01–1.0 M sodium acetate. The mobility of dsDNA is greater than that of ssDNA at all ionic strengths because of the greater charge density of dsDNA. The mobilities of both ssDNA and dsDNA decrease with increasing ionic strength until approaching plateau values at ionic strengths greater than ∼0.6 M. Hence, ssDNA and dsDNA appear to interact in a similar manner with the ions in the background electrolyte. For dsDNA, the mobilities predicted by the Manning electrophoresis equation are reasonably close to the observed mobilities, using no adjustable parameters, if the average distance between phosphate residues (the b parameter) is taken to be 1.7 Å. For ssDNA, the predicted mobilities are close to the observed mobilities at ionic strengths ≤0.01 M if the b-value is taken to be 4.1 Å. The predicted and observed mobilities diverge strongly at higher ionic strengths unless the b-value is reduced significantly. The results suggest that ssDNA strands exist as an ensemble of relatively compact conformations at high ionic strengths, with b-values corresponding to the relatively short phosphate-phosphate distances through space.     

Electrophoretic Mobility of Amylase in Drosophilids Indicates Adaptation to Ecological Diversity

Understanding the significance of electrophoretic variation is of interest for both ecological and evolutionary genetics. Although there has been a very active neutralist–selectionist debate about the patterns of electrophoretic variation in natural populations, it is only recently that charged amino acids have been shown to be important in enzyme adaptation. In this study we carried out a broad electrophoretic survey of amylase variation in 150 species of Drosophilids. The distribution of amylase electromorphs was found to be correlated with the geographical origin of the flies. Generally the faster migrating variants are found in warmer temperatures. There is also a correlation with the feeding habits of the species, in particular, fungus feeders consistently showed a deviating pattern of electrophoretic mobility. These correlations between ecological diversity and electrophoretic patterns indicate that at least some of the changes in charged amino acids are adaptive, and result from selection to cope with specific environments.     

A Model Allowing Continuous Variation in Electrophoretic Mobility of Neutral Alleles

The infinite-sites model with no recombination is extended to include mutations that affect electrophoretic mobility. The model allows the effect of a single-site mutation to have a continuous effect on mobility. Formulae are obtained for the variance of electrophoretic mobility of alleles after an arbitrary lenght of time. A special case of the general model is the case of stepwise production of neutral alleles with an arbitrary number of steps.     

Action of a Pyrimido-pyrimidine Compound on Platelet Behaviour in Vitro

A pyrimido-pyrimidine compound (RA433) was found in vitro to be a significantly more potent inhibitor of platelet behaviour than the previously available pyrimido-pyrimidine compound RA8—dipyridamole. In a turbidimetric system RA433 inhibits platelet aggregation induced by adenosine diphosphate, collagen, and noradrenaline; further, in a glass-bead-column technique it is a powerful inhiitor of platelet adhesiveness.     

Capillary Electrophoresis Measurements of Electrophoretic Mobility for Colloidal Particles of Biological Interest

The electrophoretic mobilities of three bacterial strains were investigated by capillary electrophoresis (CE) and were compared with results obtained by microelectrophoresis (ME). The CE measurements yielded bimodal electropherograms for two of the strains, thus illustrating for the first time that surface charge variations within a monoclonal population can be probed by CE. Intrapopulation variations were not detected by ME. The mobilities of three chemically distinct types of latex microspheres were also measured. Differences between the mean mobilities obtained by CE and ME were not statistically significant (P ≤ 0.50); the standard deviations of the CE measurements were typically 2 to 10 times smaller than those obtained by comparable ME measurements. The reproducibility of CE permitted batch-to-batch mobility variations to be probed for the bacteria (one of the strains exhibited such variations), and aggregation was evident in one of the latex suspensions. These effects were not measurable with ME.     

Differential Response of B and T Cells to ALS revealed by Electrophoretic Mobility Determinations

SINCE their discovery anti-lymphocyte antisera (ALS) have been widely investigated in order to clarify their mode of action and to determine their usefulness in clinical practice. Briefly, it seems that the efficacy of a particular ALS depends on its mode of production and on the method adopted for testing its immunosuppressive effect. It also seems likely that many ALS have a harmful effect on a population of thymus-dependent (T) lymphocytes¹. It is the intention of this paper to confirm this notion and to indicate that other lymphocytes (B cells) are likely to be less affected by ALS.     

Effect of pH on the Electrophoretic Mobility of Spores of Bacillus anthracis and Its Surrogates in Aqueous Solutions

The electrophoretic mobility (EPM) of endospores of Bacillus anthracis and surrogates was measured in aqueous solution across a broad pH range and several ionic strengths. EPM values trended around phylogenetic clustering based on the 16S rRNA gene. Measurements reported here provide new insight for Bacillus anthracis surrogate selection and for attachment/detachment and transport studies.     

Calculation of the Electrophoretic Mobility of a Particle Bearing Bound Polyelectrolyte Using the Nonlinear Poisson-Boltzmann Equation

A numerical method for determining the electrophoretic mobility of a polyelectrolyte-coated particle is presented. The particle surface is modeled as having a permeable layer of polyelectrolyte molecules anchored to its surface. Fluid flow within the polyelectrolyte layer is subject to Stokes drag arising from the polyelectrolyte segments. The method allows arbitrary distribution of polymer segments and charge density normal to the surface to be used. The hydrodynamic plane of shear may also be varied. The potential profile is determined by a numerical solution to the nonlinearized Poisson-Boltzmann equation. The potential profile is then used in a numerical solution to the Navier-Stokes equation to give the required mobility. The use of the nonlinearized Poisson-Boltzmann equation extends the results to higher charge density/lower ionic strength conditions than previous treatments. The surface potentials and mobilities for three limiting charge distributions are compared for both the linear and nonlinear treatments to delimit the range of validity of the linear treatment. The utility of the numerical, nonlinear treatment is demonstrated by an improved fit to the electrophoretic mobility of human erythrocytes as a function of ionic strength in the range 10 to 150 mM.     

Surface Charge of Trypanosoma cruzi. Binding of Cationized Ferritin and Measurement of Cellular Electrophoretic Mobility*

SYNOPSIS The surface charge of epimastigote and trypomastigote forms of Trypanosoma cruzi was evaluated by means of binding of cationized ferritin to the cell surface as visualized by electron microscopy, and by direct measurements of the cellular microelectrophoretic mobility (EPM). Epimastigote forms had a mean EPM of -0.52 μm^.s^-1.V^-1.cm and were lightly labeled with cationized ferritin. In contrast, bloodstream trypomastigotes had a much higher EPM (-1.14), and the surface was heavily labeled with cationized ferritin. When trypomastigotes from stationary phase cultures were isolated on DEAE cellulose columns, the mean EPM was found to be significantly lower (-0.63), and labeling with cationized ferritin decreased. With a mixed population containing epimastigote, trypomastigote, and intermediate forms, EPM values ranging between -0.70 to -1.14 were found. From these observations we conclude that there is a definite increase in negative surface charge during development from epi- to trypomastigote forms of T. cruzi.     

Astroglial Mechanisms of Ketamine Action Include Reduced Mobility of Kir4.1-Carrying Vesicles

Neurochemical Research - The finding that ketamine, an anaesthetic, can elicit a rapid antidepressant effect at low doses that lasts for weeks in patients with depression is arguably a major...