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1.
Interaction of lectins with a detergent-solubilized ATPase from eel electric organ was studied. Concanavalin A, which binds to alpha-mannosides, altered the rate of enzyme migration in agar and inhibited the formation of an antigen-antibody precipitate: other lectins had no such effects. Concanavalin A similar amounts partially inhibited (Na+ + K+)-ATPase; this inhibition was reversible by alpha-methylglucoside. There was no corresponding effect of concanavalin A on the potassium p-nitrophenylphosphatase. Concanavalin A also did not interfere with ouabain binding. Thus, concanavalin A binds to an antigenic region also involved in Na+ and/or ATP binding, but does not interact with a K+ site. 相似文献
2.
It has been well established that there is considerable genetic variability in resistance of domestic animals to nematode parasites. Utilization of this resource to reduce dependency on present parasite control methods will take place only if breeding for resistance is shown to be a profitable control strategy. Therefore, a cost/benefit analysis is needed, but most of the information required for that is still lacking.Resistance is a complex character and any selection criterion used in a selective breeding program can only cover part of all mechanisms involved. Moreover, one should take into consideration that it might be worthwhile to select animals for their capacity to overcome the pathogenic effects of infection rather than the infection itself.Selection criteria used in genetic experiments to date are too complicated to be practicable. There is a great need for simple and cheap procedures to identify genetically superior individuals. Genetic variability of resistance is large enough to allow a reasonable rate of progress to be obtained by practicable breeding programs. Furthermore, if major resistance genes could be identified, as is suggested by some work, a suitable breeding strategy would have an enormous impact. 相似文献
3.
The extreme thermoacidophiles of the genus Sulfolobus are among the best-studied archaea but have lacked small, reliable plasmid vectors, which have proven extremely useful for manipulating and analyzing genes in other microorganisms. Here we report the successful construction of a series of Sulfolobus–Escherichia coli shuttle vectors based on the small multicopy plasmid pRN1 from Sulfolobus islandicus. Selection in suitable uracil auxotrophs is provided through inclusion of pyrEF genes in the plasmid. The shuttle vectors do not integrate into the genome and do not rearrange. The plasmids allow functional overexpression of genes, as could be demonstrated for the β-glycosidase (lacS) gene of S. solfataricus. In addition, we demonstrate that this β-glycosidase gene could function as selectable marker in S. solfataricus. The shuttle plasmids differ in their interruption sites within pRN1 and allowed us to delineate functionally important regions of pRN1. The orf56/orf904 operon appears to be essential for pRN1 replication, in contrast interruption of the highly conserved orf80/plrA gene is tolerated. The new vector system promises to facilitate genetic studies of Sulfolobus and to have biotechnological uses, such as the overexpression or optimization of thermophilic enzymes that are not readily performed in mesophilic hosts. 相似文献
4.
Marian C. Cheung Gertrud Wolfbauer Hiroshi Deguchi José A. Fernández John H. Griffin John J. Albers 《Biochimica et Biophysica Acta (BBA)/Molecular and Cell Biology of Lipids》2009,1791(3):206-211
To gain further insights into the relationship between plasma phospholipid transfer protein (PLTP) and lipoprotein particles, PLTP mass and phospholipid transfer activity were measured, and their associations with the level and size of lipoprotein particles examined in 39 healthy adult subjects. No bivariate correlation was observed between PLTP activity and mass. PLTP activity was positively associated with cholesterol, triglyceride, apo B and VLDL particle level (rs = 0.40–0.56, p ≤ 0.01) while PLTP mass was positively associated with HDL-C, large HDL particles, and mean LDL and HDL particle sizes (rs = 0.44–0.52, p < 0.01). Importantly, plasma PLTP specific activity (SA) was significantly associated with specific lipoprotein classes, positively with VLDL, IDL, and small LDL particles (rs = 0.42–0.62, p ≤ 0.01) and inversely with large LDL, large HDL, and mean LDL and HDL particle size (rs = − 0.42 to − 0.70, p ≤ 0.01). After controlling for triglyceride levels, the correlation between PLTP mass or SA and HDL size remained significant. In linear models, HDL size explained 45% of the variability of plasma PLTP SA while triglyceride explained 34% of the PLTP activity. Thus, in healthy adults a significant relationship exists between HDL size and plasma PLTP SA (rs = − 0.70), implying that HDL particle size may modulate PLTP SA in the vascular compartment. 相似文献
5.
The purpose of this experiment was to characterize the high density lipoproteins (HDL) as a function of hydrated density. HDL was subfractionated on the basis of hydrated density by CsCl density gradient centrifugation of whole serum or the d 1.063-1.25 g/ml HDL fraction isolated from three men and three women. Apolipoprotein A-I and A-II quantitation by radial immunodiffusion showed that the A-I/A-II ratio varied with the lipoprotein hydrated density. The A-I/A-II molar ratio of HDL lipoproteins banding between d 1.106 and 1.150 g/ml was nearly constant at 2.2 +/- 0.2. In the density range 1.151-1.25 g/ml the A-I/A-II ratio increased as the density increased. On the other hand, in the density range between 1.077 and 1.105 the A-I/A-II ratio increased as the density decreased, ranging from 2.8 +/- 0.5 for the d 1.093-1.105 g/ml fraction to 5.6 +/- 1.3 for the d 1.077-1.082 g/ml fraction. The d 1.063-1.076 g/ml fraction and the d 1.077-1.082 g/ml fractions had comparable A-I/A-II ratios. Serum and the d 1.063-1.25 g/ml HDL fraction exhibited similar trends. The cholesterol/(A-I + A-II) ratio decreased as the density increased in all 12 samples (six serum and six HDL) examined. Gradient gel electrophoresis of the density gradient fractions showed that as the density increased from 1.063 to 1.200 g/ml the apparent molecular weight decreased from 3.9 x 10(5) to 1.1 x 10(5). HDL subfractions with the same hydrated densities had comparable molecular weights and A-I/A-II and cholesterol/(A-I + A-II) ratios when isolated from men or women. HDL contains subpopulations that differ in the A-I/A-II molar ratio.-Cheung, M. C., and J. J. Albers. Distribution of cholesterol and apolipoprotein A-I and A-II in human high density lipoprotein subfractions separated by CsCl equilibrium gradient centrifugation: evidence for HDL subpopulations with differing A-I/A-II molar ratios. 相似文献
6.
Paul M. Rowe William T. Link Charlene P. Osborn Harold Gainer R. Wayne Albers 《Journal of neurochemistry》1991,57(3):1088-1090
The distributions of alpha-subunit isoforms of the Na+,K(+)-ATPase in rat pituitary were determined by immunoblotting and immunohistochemistry. Immunoreactivity for all three forms is present in the neural lobe, whereas the anterior lobe contains only alpha 1 and alpha 2. Most areas of the intermediate lobe exhibit faint immunoreactivity for only alpha 1, but thin strands of cells which stain strongly for all three isoforms are also present in this lobe. The previously reported ouabain inhibitable Na+,K(+)-ATPase activity in the neural lobe is consistent with the presence of both alpha 2 and alpha 3 subunits. 相似文献
7.
Federico L Ren H Mueller PA Wu T Liu S Popovic J Blalock EM Sunkara M Ovaa H Albers HM Mills GB Morris AJ Smyth SS 《Molecular endocrinology (Baltimore, Md.)》2012,26(5):786-797
Brown adipose tissue is a thermogenic organ that dissipates stored energy as heat to maintain body temperature. This process may also provide protection from development of diet-induced obesity. We report that the bioactive lipid mediator lysophosphatidic acid (LPA) markedly decreases differentiation of cultured primary brown adipocyte precursors, whereas potent selective inhibitors of the LPA-generating enzyme autotaxin (ATX) promote differentiation. Transgenic mice overexpressing ATX exhibit reduced expression of brown adipose tissue-related genes in peripheral white adipose tissue and accumulate significantly more fat than wild-type controls when fed a high-fat diet. Our results indicate that ATX and its product LPA are physiologically relevant negative regulators of brown fat adipogenesis and are consistent with a model in which a decrease in mature peripheral brown adipose tissue results in increased susceptibility to diet-induced obesity in mice. 相似文献
8.
9.
Ching-Hong Chen John J. Albers 《Biochemical and biophysical research communications》1982,107(3):1091-1096
The distribution of lecithin-cholesterol acyltransferase (LCAT) in human plasma was assessed by measuring both LCAT mass and activity in plasma fractions separated by sequential flotation ultracentrifugation, single-spin gradient ultracentrifugation, dextran sulfate-Mg2+ precipitation or agarose gel filtration. Although most of the LCAT was found to be associated with the high density lipoprotein fraction, a small amount of active LCAT (approximately 1% of the plasma LCAT mass and activity) was consistently associated with the low density lipoprotein fraction. LCAT was not found in the very low density lipoprotein fraction. The LDL-associated LCAT may play an important role in the acylation of lysolecithin by lysolecithin acyltransferase activity of LCAT. 相似文献
10.
Cheung MC Brown BG Marino Larsen EK Frutkin AD O'Brien KD Albers JJ 《Biochimica et biophysica acta》2006,1762(1):131-137
Plasma phospholipid lipid transfer protein (PLTP) has several known key functions in lipoprotein metabolism. Recent studies suggest that it also may play a role in the inflammatory response. Inflammatory cell activity contributes to the development of atherosclerosis. To seek further evidence for the association of PLTP with inflammation, we studied the relationship between PLTP activity and five inflammatory markers [C-reactive protein (CRP), serum amyloid A (SAA), interleukin 6 (IL-6), white blood cells (WBC), and fibrinogen] in 93 patients with low HDL and cardiovascular disease (CVD). Plasma PLTP activity had the strongest correlation with CRP (r=0.332, P<0.001) followed by SAA (r=0.239, P=0.021). PLTP, CRP, and SAA were significantly associated with body mass index (BMI), insulin or glucose, apolipoprotein (apo) B, and/or apo E level (r=0.264-0.393, P<0.01). PLTP, SAA, and IL-6 also were associated with the concentration of HDL particles without apo A-II [Lp(A-I)](r=0.373-0.472, P<0.005, n=56), but not particles with apo A-II. Smoking was associated with increased PLTP activity, CRP, and WBC, and hypertension with increased PLTP activity. In linear models, CRP remained significantly associated with PLTP after adjustment of CVD risk factors and insulin resistance. Also, much of the variability of plasma PLTP activity was explained by CRP, BMI, Lp(A-I), smoking, glucose, and blood pressure. These findings show for the first time that plasma PLTP activity is associated positively with CRP in CVD, a state of chronic inflammation. 相似文献