Lipoprotein patterns in acrylamide gel electrophoresis

Nongenetic variation, genetic-environmental interactions and altered gene expression. II. Disease, parasite and pollution effects

The use of protein electrophoretic data for determining the relationships among species or populations is widespread and generally accepted. However, there are many confounding factors that may alter the results of an electrophoretic study and may possibly allow erroneous conclusions to be drawn in taxonomic, systematic or population studies. Measured enzyme activities can also be affected significantly. Parasites, disease and pollution can affect levels of enzyme activity, and electrophoretic results can be affected both quantitatively and qualitatively. Blood serum is particularly vulnerable to variation to variation due to disease, pollution or parasites because damaged tissues may release tissue-specific enzymes into the bloodstream. Capture, handling, chemical treatments, bacteria, natural toxins and consumed food may also contribute to variation. Potential pollution impacts at specimen collection sites should be investigated, and study organisms should be inspected and/or treated for detection and elimination of parasites and disease.

Gradient acrylamide/agarose gels for electrophoretic separation of intact human very low density lipoproteins, intermediate density lipoproteins, lipoprotein a, and low density lipoproteins

An exponential gradient gel with 0-10% acrylamide and 0.5% agarose was developed for electrophoresis of intact high molecular weight lipoproteins. This system resolves very low density lipoproteins, intermediate density lipoproteins, lipoprotein a, and low density lipoproteins in a size-dependent fashion. The characteristic relative mobility of these species can be determined in relation to protein and colloidal gold reference materials. Electron microscopy of selected lipoprotein fractions confirmed that relative mobility was related to apparent lipoprotein diameter. The composite gel medium can be used with prestained lipoproteins and permits immunoelectroblotting for qualitative analysis of apolipoprotein constituents.

Biochemical and immunological characterization of the variant surface coat glycoprotein shed by African trypanosomes

As the variant surface coat glycoprotein (VSG) was shed from Trypanosoma brucei rhodesiense into the blood of infected rats, it was biochemically characterized and compared with VSG that had been purified from trypanosomal homogenates. To determine if VSG was in association with lipid, membranes and lipoproteins in plasma of infected rats (IRP), VSG isolated from plasma (PVSG), and VSG isolated from trypanosomal homogenates (HVSG) were all concentrated by ultracentrifugation and assayed for the presence of VSG by radial immunodiffusion (minimum level of detection, 25 micrograms/ml) and by immunoelectroblots (minimum level of detection, 1 microgram/ml). Crimson red was used to detect lipid (minimum level of detection, 10 micrograms per sample) in electrophoresed samples. The VSG was neither concentrated with membrane or lipoprotein fractions nor stained by lipid crimson. Lipids from normal rat plasma, IRP, trypanosomal homogenates, HVSG, and PVSG were also extracted and separated by thin-layer chromatography (minimum level of detection, 20 micrograms of trypanosomal phospholipid per sample). The trypanosomal homogenates had five bands as detected by iodine vapors, of which three were phospholipids as detected by molybdenum blue. Both normal rat plasma and IRP had identical patterns of bands with a single phospholipid. The PVSG had one neutral lipid contaminant that apparently was not physically associated with the shed surface coat. The HVSG contained no lipids at all. Therefore, no evidence was obtained to implicate an association between membranes and VSG, once the latter had been shed into the blood of infected hosts. From immunoelectroblots of denatured material, it was determined that both HVSG and PVSG had the same reduced molecular weight. From molecular sieve column chromatography, however, it was determined that VSG released during the homogenization of trypanosomes is a noncovalently linked dimer, whereas that shed in the blood is apparently a trimer. This difference in native structure made no difference in immunological effect. Administered in a regimen that mimicked what the host encounters during a first peak of parasitemia, both HVSG and PVSG induced nonspecific proliferation of splenic lymphocytes and production of unelicited antibodies without the generation of nonspecific immunosuppression. This polyclonal activation of lymphocytes was not the result of contamination by exogenous pyrogen, because the activity was lost if VSG was immunologically absorbed from plasma.(ABSTRACT TRUNCATED AT 400 WORDS)

Reversible thermal conformation changes in human serum low-density lipoprotein

Human serum beta(1) (LDL(2)) lipoprotein was preparatively divided into three subfractions on the basis of density, and the protein conformation was investigated by optical rotatory dispersion and circular dichroism. The protein conformation was found to vary substantially as a function of lipid composition and temperature in a gradual and reversible manner. Surprisingly, the reversible temperature range includes physiological temperature. From the character of the spectra, it appears that alpha-helix, disordered, and beta conformations can be present in the protein moiety. The presence of these conformations and their distribution appears to depend upon both lipid content and temperature. The importance of this conformational flexibility in its relation to the role of the lipoprotein in lipid transport is discussed.

Human serum α-1-lipoprotein patterns revealed by starch gel electrophoresis

The recognition of different serum alpha-1-lipoproteins patterns was made possible by improved lipoprotein staining and separation methods. Three common and some less common patterns were found. The common alpha-1-lipoprotein patterns, here called S, M and F, were found to differ in their relative frequency in men and women, and to be associated with significantly different serum alpha-1-lipoprotein concentrations.