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761.
Eyal Seroussi Shelly Klompus Maayan Silanikove Oleg Krifucks Fira Shapiro Arieh Gertler Gabriel Leitner 《Immunogenetics》2013,65(12):861-871
The recent burst of duplication and divergence of the bovine PLA2G2D genes is considered typical of immune response genes, and it was recently shown that PLA2G2D is abundantly expressed in mouse leukocytes and acts as an immunosuppressive phospholipase. Analysis of 1,143 Holstein bulls indicated that the four common haplotypes spanning PLA2G2D display copy number variation ranging from 1 to 4 per haploid genome. Association of the fourth haplotype with negative total merit remained significant (P?<?0.002) when corrected for population relatedness. We compared the lipase and bactericidal activities of bovine pancreatic PLA2G1B with human PLA2G2A and G2D and bovine PLA2G2D1 and G2D4 proteins, which had been subcloned, expressed, and refolded by us, and the impact of point mutations in the calcium binding site was investigated. All tested phospholipases were ineffective bactericides of Escherichia coli isolated from bovine mastitis. However, in lactating mice treated with E. coli or lipopolysaccharide (LPS), intramammary injection of bovine PLA2G1B relieved visual and histological inflammation and reduced blood levels of infiltrating lactose. Further studies are warranted to determine whether the observed anti-inflammatory effect involves competitive binding of the receptor Pla2r1 which may mimic the LPS resistance effect in Pla2r1-deficient mice. 相似文献
762.
Molecular size heterogeneity of human leukocyte interferon 总被引:3,自引:0,他引:3
Molecular sieving of human leukocyte interferon revealed an apparent molecular weight of 26,000. However, after denaturation by guanidine hydrochloride in the presence of a reducing agent and reactivation by extensive dialysis, a molecular weight of only 21,000 was observed. The reactivated human leukocyte interferon (mol wt 21,000) gave a single peak of activity when analyzed by sodium dodecyl sulfate-polyacrylamide gel electrophoresis, confirming that a single molecular weight species was generated by the denaturation and reactivation procedure. A partial unfolding of the molecule was evident when the interferon preparation was heated to 50 degrees C in the absence or presence of an unfolding agent and then sieved on Sephadex G-100 Superfine. These results suggest that the interferon molecule undergoes a proteolytic cleavage probably by a protease present in extracellular fluid. Thus, a peptide fragment dissociates from the parent molecule when human leukocyte interferon is denatured in the presence of a reducing agent, resulting in a drop of 5,000 in molecular weight; interestingly, the resultant 21,000 molecular weight form still retains its antiviral activity. 相似文献
763.
T. Hilton Grayson Preet S. Chadha Paul P. Bertrand Hui Chen Margaret J. Morris Sevvandi Senadheera Timothy V. Murphy Shaun L. Sandow 《Histochemistry and cell biology》2013,139(2):309-321
Diet-induced obesity induces changes in mechanisms that are essential for the regulation of normal artery function, and in particular the function of the vascular endothelium. Using a rodent model that reflects the characteristics of human dietary obesity, in the rat saphenous artery we have previously demonstrated that endothelium-dependent vasodilation shifts from an entirely nitric oxide (NO)-mediated mechanism to one involving upregulation of myoendothelial gap junctions and intermediate conductance calcium-activated potassium channel activity and expression. This study investigates the changes in NO-mediated mechanisms that accompany this shift. In saphenous arteries from controls fed a normal chow diet, acetylcholine-mediated endothelium-dependent vasodilation was blocked by NO synthase and soluble guanylyl cyclase inhibitors, but in equivalent arteries from obese animals sensitivity to these agents was reduced. The expression of endothelial NO synthase (eNOS) and caveolin-3 in rat saphenous arteries was unaffected by obesity, whilst that of caveolin-1 monomer and large oligomeric complexes of caveolins-1 and -2 were increased in membrane-enriched samples. The density of caveolae was increased at the membrane and cytoplasm of endothelial and smooth muscle cells of saphenous arteries from obese rats. Dissociation of eNOS from caveolin-1, as a prerequisite for activation of the enzyme, may be compromised and thereby impair NO-mediated vasodilation in the saphenous artery from diet-induced obese rats. Such altered signaling mechanisms in obesity-related vascular disease represent significant potential targets for therapeutic intervention. 相似文献
764.
Booysen Elzaan Bezuidenhout Martin van Staden Anton Du Preez Dimitrov Dimiter Deane Shelly M. Dicks Leon M. T. 《Probiotics and antimicrobial proteins》2019,11(1):310-316
Probiotics and Antimicrobial Proteins - Vancomycin is often used to treat infections caused by β-lactam-resistant bacteria. However, methicillin-resistant strains of Staphylococcus aureus... 相似文献
765.
Males of the Mediterranean fruit fly, Ceratitis capitata (medfly), defend individual leaves of host and non-host trees as mating territories and attract females via production of
a sex pheromone (a behavior termed ‘calling’). Males tend to aggregate within the tree canopy, and the present study examined
the influence of (1) location and (2) resources on female visitation to male aggregations. Males were placed in screen-covered
containers, which were suspended on field-caged trees at two locations selected to differ in only one of the following parameters:
height above ground (low versus high), leaf density (sparse versus dense), distance to main trunk (canopy edge versus center),
proximity to a food source (bird feces absent or present), and proximity to a host fruit (oranges absent or present). Females
were released, and we periodically recorded the number of calling males in each of the test aggregations as well as the number
of females sighted within 15 cm of each male aggregation. Male calling did not differ between treatments in any of the experiments.
However, females were more frequently sighted near males calling (1) in dense foliage, (2) near the central trunk, (3) near
bird feces, and (4) near oranges. In an additional experiment, we compared male settlement (in the absence of females) on
leaves in the same sites used previously to determine the degree of congruence between the sexes in microhabitat use. Aside
from the lack of center-edge effect, males displayed the same settlement patterns as females. In a final experiment, we found
no effect of male calling on the distribution of other males: released males were sighted with equal frequency near cups containing
mature, calling males and cups containing immature, non-calling males. Medfly lek behavior is discussed in light of these
findings. 相似文献
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The present study investigates the mechanism of zymosan-activated plasma (ZAP)-mediated eicosanoid production by the isolated, perfused rabbit liver and described ZAP-mediated eicosanoid stimulation in cultured hepatocytes. Perfused livers receiving untreated plasma demonstrated no significant changes in portal venous pressure or the rates of release of lactic dehydrogenase or acid phosphatase activity (indicators of cellular injury). The control group livers demonstrated stable rates of release for 6-keto PGF1 alpha and thromboxane B2 (TXB2). In contrast, the infusion of ZAP alone resulted in a rapid but transient release of TXB2 from the livers. No significant changes in perfusion pressure or enzyme release were observed following ZAP administration. Perfusion of livers with a calcium-free buffer decreased the basal rates of both 6-keto PGF1 alpha and TXB2 production and significantly, but not completely, attenuated the ZAP-mediated increase in hepatic TXB2 production. Perfusion of livers with nifedipine (3 microM) had no effect on ZAP-mediated TXB2 production in this model. Isolated hepatocytes responded to ZAP-treatment with significant increases in TXB2 production. These data suggest that activated fluid phase complement components induce thromboxane production by specific cells within the liver and that this stimulation is partially dependent upon the release of intracellular calcium but independent of complement-mediated cellular injury. 相似文献