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61.
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
62.
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
63.
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64.
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
65.
Moraxella osloensis is a gram-negative bacterium associated with Phasmarhabditis hermaphrodita, a slug-parasitic nematode that has prospects for biological control of mollusk pests, especially the grey garden slug, Deroceras reticulatum. This bacterium-feeding nematode acts as a vector that transports M. osloensis into the shell cavity of the slug, and the bacterium is the killing agent in the nematode-bacterium complex. We discovered that M. osloensis produces an endotoxin(s), which is tolerant to heat and protease treatments and kills the slug after injection into the shell cavity. Washed or broken cells treated with penicillin and streptomycin from 3-day M. osloensis cultures were more pathogenic than similar cells from 2-day M. osloensis cultures. However, heat and protease treatments and 2 days of storage at 22 degrees C increased the endotoxin activity of the young broken cells but not the endotoxin activity of the young washed cells treated with the antibiotics. This suggests that there may be a proteinaceous substance(s) that is structurally associated with the endotoxin(s) and masks its toxicity in the young bacterial cells. Moreover, 2 days of storage of the young washed bacterial cells at 22 degrees C enhanced their endotoxin activity if they were not treated with the antibiotics. Furthermore, purified lipopolysaccharide (LPS) from the 3-day M. osloensis cultures was toxic to slugs, with an estimated 50% lethal dose of 48 microg per slug, thus demonstrating that the LPS of M. osloensis is an endotoxin that is active against D. reticulatum. This appears to be the first report of a biological toxin that is active against mollusks. 相似文献
66.
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
67.
Ravinder Kaur Grewal Monika Lulsdorf Janine Croser Sergio Ochatt Albert Vandenberg Thomas D. Warkentin 《Plant cell reports》2009,28(8):1289-1299
This is the first report on the production of double-haploid chickpea embryos and regenerated plants through anther culture
using Canadian cultivar CDC Xena (kabuli) and Australian cultivar Sonali (desi). Maximum anther induction rates were 69% for
Sonali and 63% for CDC Xena. Under optimal conditions, embryo formation occurred within 15–20 days of culture initiation with
2.3 embryos produced per anther for CDC Xena and 2.0 embryos per anther for Sonali. For anther induction, the following stress
treatments were used: (1) flower clusters were treated at 4°C for 4 days, (2) anthers were subjected to electric shock treatment
of three exponentially decaying pulses of 50–400 V with 25 μF capacitance and 25 Ω resistance, (3) anthers were centrifuged
at 168–1,509g for 2–15 min, and finally (4) anthers were cultured for 4 days in high-osmotic pressure (563 mmol) liquid medium. Anthers
were then transferred to a solid embryo development medium and, 15–20 days later, embryo development was observed concomitant
with a small amount of callus growth of 0.1–3 mm. Anther-derived embryos were regenerated on plant regeneration medium. Electroporation
treatment of anthers enhanced root formation, which is often a major hurdle in legume regeneration protocols. Cytological
studies using DAPI staining showed a wide range of ploidy levels from haploid to tetraploid in 10–30-day-old calli. Flow cytometric
analysis of calli, embryos and regenerated plants showed haploid profiles and/or spontaneous doubling of the chromosomes during
early regeneration stages. 相似文献
68.
A crown rot disease in wheat caused by the fungusFusarium graminearum Schw. Group 1 is a widespread problem in chronically Zn-deficient Australian soils. A link between crown rot and Zn deficiency
was established by Sparrow and Graham (1988). This paper reports a test of a further hypothesis, that wheat genotypes more
efficient at extracting zinc from low-zinc soils are more resistant to infection by this pathogen. Three wheat cultivars (Excalibur,
Songlen and Durati) of differential Zn efficiency were tested at three zinc levels (0.05, 0.5 and 2.0 mg Zn kg−1 of soil) and three levels ofF. graminearum S. Group 1 inoculum (0.1 g and 0.3 g kg−1 live chaff-inoculum and control having 0.1 g kg−1 dead chaff inoculum). Six weeks after sowing dry matter production of shoots and roots was decreased byFusarium inoculation at 0.05 mg and 0.5 mg kg−1 applied Zn.Fusarium inoculum at 0.1 g was as effective as 0.3 g kg−1 for infection and decreasing dry matter. The infection at the basal part of culm decreased significantly by increasing the
rate of Zn application. Excalibur, a Zn-efficient cultivar (tolerant to Zn deficiency) produced significantly more shoot and
root dry matter, and showed less disease infection compared with Zn-inefficient cultivars (Durati and Songlen) at low (0.05
mg Zn kg−1 soil) and medium (0.5 mg Zn kg−1 soil) Zn fertilization rates. Higher rate of Zn fertilization (2.0 mg Zn kg−1 soil) reduced the disease level in Durati to the level of Excalibur but the disease level of Songlen was still high, indicating
its high Zn requirement and or sensitivity to crown rot. The data on Zn uptake show that Excalibur, being Zn-efficient, was
able to scavenge enough Zn from Zn-deficient soil, we suggest that besides sustaining growth Excalibur was able to build and
maintain resistance to the pathogen; inefficient cultivars needed extra Zn fertilization to achieve performance comparable
to that of Excalibur. The present study indicates that growing Zn-efficient cultivars of wheat along with judicious use of
Zn fertilizer in Zn-deficient areas where crown rot is a problem may sustain wheat production by reducing the severity of
the disease as well as by increasing the plant vigour through improved Zn nutrition. ei]Section editor: R Rodriques-Kalana 相似文献
69.
Almost all animals show sex differences in body size. For example, in Drosophila, females are larger than males. Although Drosophila is widely used as a model to study growth, the mechanisms underlying this male-female difference in size remain unclear. Here, we describe a novel role for the sex determination gene transformer (tra) in promoting female body growth. Normally, Tra is expressed only in females. We find that loss of Tra in female larvae decreases body size, while ectopic Tra expression in males increases body size. Although we find that Tra exerts autonomous effects on cell size, we also discovered that Tra expression in the fat body augments female body size in a non cell-autonomous manner. These effects of Tra do not require its only known targets doublesex and fruitless. Instead, Tra expression in the female fat body promotes growth by stimulating the secretion of insulin-like peptides from insulin producing cells in the brain. Our data suggest a model of sex-specific growth in which body size is regulated by a previously unrecognized branch of the sex determination pathway, and identify Tra as a novel link between sex and the conserved insulin signaling pathway. 相似文献
70.