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71.
We studied variation in isozyme patterns of 8 metabolic enzymes in 5 species of Heterorhabditis (H. bacteriophora, H. indica, H. marelata, H. megidis, and H. zealandica) comprising 18 isolates. Isozyme banding patterns of all the 8 enzymes were species specific; however, 3 enzymes, i.e., arginine kinase, fumarate hydratase, and malate dehydrogenase, displayed distinct patterns among all the 18 isolates. Phylogenetic analysis of the isozyme patterns produced dendrograms depicting a high degree of genetic variation among Heterorhabditis species, with the average pairwise distance of 0.2000. Trees constructed using different phylogenetic methods showed a relatively close genetic relationship between H. megidis and H. zealandica and between H. bacteriophora and H. indica. Also, H. bacteriophora HP88 was the most distant species from H. megidis (UK isolate), H. marelatus (Oregon isolate), and H. zealandica (X1 isolate) with pairwise distance of 0.1957, 0.2228, and 0.2120, respectively. Phylogenetic analysis also revealed genetic variation among H. bacteriophora isolates with the average pairwise distance of 0.1507. GPS2 and GPS3 were the most closely related isolates with the average distance of only 0.0870, followed by GPS1 and GPS2 with average distance of 0.1087. In contrast, KMD19 and HP88, OH25, and HP88, and OH25 and Acows isolates were the most divergent populations with a pairwise distance of 0.2011 and 37 character differences. Pairwise distance analysis also revealed that genetic divergence among populations of H. bacteriophora is relatively independent of geographic distance. Overall, these results demonstrate strong subspecies structuring in H. bacteriophora. 相似文献
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74.
Salti SM Hammelev EM Grewal JL Reddy ST Zemple SJ Grossman WJ Grayson MH Verbsky JW 《Journal of immunology (Baltimore, Md. : 1950)》2011,187(12):6301-6309
CTLs and NK cells use the perforin/granzyme cytotoxic pathway to kill virally infected cells and tumors. Human regulatory T cells also express functional granzymes and perforin and can induce autologous target cell death in vitro. Perforin-deficient mice die of excessive immune responses after viral challenges, implicating a potential role for this pathway in immune regulation. To further investigate the role of granzyme B in immune regulation in response to viral infections, we characterized the immune response in wild-type, granzyme B-deficient, and perforin-deficient mice infected with Sendai virus. Interestingly, granzyme B-deficient mice, and to a lesser extent perforin-deficient mice, exhibited a significant increase in the number of Ag-specific CD8(+) T cells in the lungs and draining lymph nodes of virally infected animals. This increase was not the result of failure in viral clearance because viral titers in granzyme B-deficient mice were similar to wild-type mice and significantly less than perforin-deficient mice. Regulatory T cells from WT mice expressed high levels of granzyme B in response to infection, and depletion of regulatory T cells from these mice resulted in an increase in the number of Ag-specific CD8(+) T cells, similar to that observed in granzyme B-deficient mice. Furthermore, granzyme B-deficient regulatory T cells displayed defective suppression of CD8(+) T cell proliferation in vitro. Taken together, these results suggest a role for granzyme B in the regulatory T cell compartment in immune regulation to viral infections. 相似文献
75.
Dispersal of organisms is influenced by environmental and innate population variability. It results in redistribution of populations with potential consequences for gene flow, population resilience and stability, and evolutionary diversification of traits in response to specific selection pressures. However, dispersal behavior in soil-dwelling organisms is understudied. Species of entomopathogenic nematodes, a group of soil-inhabiting lethal insect parasites used in biological pest control show a dichotomy in foraging behavior. Some species have been classified as ambushers while others as cruisers. We previously discovered that the ambush foraging Steinernema carpocapsae possesses a small group of sprinters that disperse faster than the fastest moving cruisers. In this study, we genetically selected S. carpocapsae for enhanced dispersal in the absence of hosts by capturing the fastest and farthest reaching infective juveniles (IJs) emanating from a nematode-infected Galleria mellonella cadaver, in soil. S. carpocapsae showed positive response to selection for dispersal with 13–23 and 21–37 fold increase in the percent IJs dispersing to the farthest distance from the source cadaver, after five and ten rounds of selection, respectively. There was also a significant increase in the average displacement of the selected lines (6.85–7.54 cm/day) than the foundation population (5.54 cm/day) maintained by passing through G. mellonella larvae in Petri dishes. The overall mean realized heritability for dispersal was 0.60. The farthest reaching IJs of the selected lines comprised more males (72 %) than the foundation population (44 %) at most time points. Trade-offs associated with enhanced dispersal included reduced reproduction capacity and nictation ability, a trait associated with ambush foraging. In conclusion, this study revealed the costs and benefits associated with selection for enhanced dispersal in a soil-dwelling insect parasite, enhancing our understanding of the evolution of new behavioral patterns, which could have important implications in biological control. 相似文献
76.
PKCβII activation is achieved by primary phosphorylation at three phosphorylation sites, followed by the addition of secondary messengers for full activation. Phosphorylation is essential for enzyme maturation, and the associated conformational changes are known to modulate the enzyme activation. To probe into the structural basis of conformational changes on phosphorylation of PKCβII, a comprehensive study of the changes in its complexes with ATP and ruboxistaurin was performed. ATP is a phosphorylating agent in its phosphorylation reaction, and ruboxistaurin is its specific inhibitor. This study provides insight into the differences in the important structural features in phosphorylated and non‐phosphorylated states of PKCβII. Less conformational changes when PKCβII is bound to inhibitor in comparison to when it is bound to its phosphorylating agent in both states were observed. The interactions of ruboxistaurin significant in restricting PKCβII to attain the conformational state competent for full activation are reported. Proteins 2014; 82:1332–1347. © 2013 Wiley Periodicals, Inc. 相似文献
77.
Synne Jenum Harleen M. S. Grewal David A. Hokey John Kenneth Mario Vaz Timothy Mark Doherty Frode Lars Jahnsen TB Trials Study Group 《PloS one》2014,9(7)
Background
QuantiFERON-TB Gold In-Tube (QFT) is an IFNγ-release assay used in the diagnosis of Mycobacterium tuberculosis (MTB) infection. The risk of TB progression increases with the magnitude of the MTB-specific IFNγ-response. QFT reversion, also associated with low Tuberculin Skin Test responses, may therefore represent a transient immune response with control of M. tuberculosis infection. However, studies at the single cell level have suggested that the quality (polyfunctionality) of the T-cell response is more important than the quantity of cytokines produced.Objective
To explore the quality and/or magnitude of mycobacteria-specific T-cell responses associated with QFT reversion and persistent QFT-positivity.Methods
Multi-color flowcytometry on prospectively collected peripheral blood mononuclear cells was applied to assess mycobacteria-specific T-cell responses in 42 QFT positive Indian adolescents of whom 21 became QFT negative (reverters) within one year. Ten QFT consistent negatives were also included as controls.Results
There was no difference in the qualitative PPD-specific CD4+ T-cell response between QFT consistent positives and reverters. However, compared with QFT consistent positives, reverters displayed lower absolute frequencies of polyfunctional (IFNγ+IL2+TNFα+) CD4+ T-cells at baseline, which were further reduced to the point where they were not different to QFT negative controls one year later. Moreover, absolute frequencies of these cells correlated well with the magnitude of the QFT-response.Conclusion
Whereas specific polyfunctional CD4+ T-cells have been suggested to protect against TB progression, our data do not support that higher relative or absolute frequencies of PPD-specific polyfunctional CD4+ T-cells in peripheral blood can explain the reduced risk of TB progression observed in QFT reverters. On the contrary, absolute frequencies of these cells correlated with the QFT-response, suggesting that this readout reflects antigenic load. 相似文献78.
Stangoulis James C. R. Grewal Harsharn S. Bell Richard W. Graham Robin D. 《Plant and Soil》2000,225(1-2):243-251
Boron (B) efficiency of oilseed rape (Brassica napus) and mustard (B. juncea) genotypes was determined on a low B soil at Mt. Compass, South Australia. B efficiency was observed in oilseed rape genotypes,
Zhongyou 821, Dunkeld and Zheyou 2, and in mustard genotypes Pusa Bold and CSIRO 6. Genotypes grown in the field were also
grown under glass-house conditions, in pots filled with pre-washed sand extracted from the Mt. Compass field site. Two B treatments,
one B adequate (0.25 mg B kg−1 soil) and one B deficient (imposed by omission) were used to indicate whether vegetative response to B could predict final
yield response and provide a more convenient selection criterion for identifying B-efficient germplasm. Vegetative response
of 35 d old (D35) genotypes grown in pot culture closely reflected field response, indicating the expression of B efficiency
traits in early growth, and its potential use in selection.
This revised version was published online in June 2006 with corrections to the Cover Date. 相似文献
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80.
Platelet-activating factor mediated effects on human neutrophil function are inhibited by pertussis toxin 总被引:4,自引:0,他引:4
P M Lad C V Olson I S Grewal 《Biochemical and biophysical research communications》1985,129(3):632-638
Pretreatment of human neutrophils with pertussis toxin inhibits platelet-activating factor-mediated chemotaxis, superoxide generation, aggregation, and release of lysozyme. By contrast, superoxide generation observed in the presence of phorbol-12-myristate-13 acetate is unaffected. Our results suggest that a target protein for pertussis toxin, probably a GTP binding protein termed "Ni", is involved in the actions of platelet-activating factor on human neutrophils. 相似文献