排序方式: 共有73条查询结果,搜索用时 15 毫秒
41.
F. E. Pitre N. J. B. Brereton S. Audoire G. M. Richter I. Shield 《Plant biosystems》2013,147(2):479-483
Abstract Non‐destructive assessment of root systems is important in order to understand and optimise the potential of resource capture and allocation by the plant. We studied the relationships between electrical capacitance (EC) and the below‐ and above‐ground biomass of willows. Cuttings of Salix viminalis × Salix schwerinii cv. Olof were maintained in pots and root development was followed up using a portable capacitance meter over the course of 2.5 months. Pot observations were compared with excavation of two‐year‐old established trees. A strong significant linear relationship (R 2 = 0.81, p < 0.001) was obtained between EC and root biomass (dry weight [DW]) for the pot experiment. EC also showed good correlations with stem and leaf biomass, as well as with stem height. In the excavated willow trees, there was a strong logarithmic relationship between EC and root biomass (R 2 = 0.66, p < 0.001). These results suggest that EC is a good estimator of below‐ground biomass in willow and may become useful in screening varieties for differences in root biomass traits, especially in distinguishing below‐ground resource allocation at an early stage. 相似文献
42.
Katayoun Omidi Mohsen Hooshyar Matthew Jessulat Bahram Samanfar Megan Sanders Daniel Burnside Sylvain Pitre Andrew Schoenrock Jianhua Xu Mohan Babu Ashkan Golshani 《PloS one》2014,9(1)
One of the main mechanisms for double stranded DNA break (DSB) repair is through the non-homologous end-joining (NHEJ) pathway. Using plasmid and chromosomal repair assays, we showed that deletion mutant strains for interacting proteins Pph3p and Psy2p had reduced efficiencies in NHEJ. We further observed that this activity of Pph3p and Psy2p appeared linked to cell cycle Rad53p and Chk1p checkpoint proteins. Pph3/Psy2 is a phosphatase complex, which regulates recovery from the Rad53p DNA damage checkpoint. Overexpression of Chk1p checkpoint protein in a parallel pathway to Rad53p compensated for the deletion of PPH3 or PSY2 in a chromosomal repair assay. Double mutant strains Δpph3/Δchk1 and Δpsy2/Δchk1 showed additional reductions in the efficiency of plasmid repair, compared to both single deletions which is in agreement with the activity of Pph3p and Psy2p in a parallel pathway to Chk1p. Genetic interaction analyses also supported a role for Pph3p and Psy2p in DNA damage repair, the NHEJ pathway, as well as cell cycle progression. Collectively, we report that the activity of Pph3p and Psy2p further connects NHEJ repair to cell cycle progression. 相似文献
43.
Background
Bacillus organisms are common laboratory contaminants. The majority of Bacillus bacteraemias are transient and not clinically significant. Clinically significant infection due to Bacillus species is rare and mostly due to Bacillus cereus infections in immuno-compromised hosts.Case presentation
We report a case of central venous catheter infection with Bacillus pumilus in an immunocompetent child with tufting enteropathy on long-term parenteral nutrition (PN). There were three episodes of central venous catheter infection with Bacillus pumilus in three months. Despite adequate and appropriate use of intravenous antibiotics, the infection failed to clear resulting in the need for removal of the catheter for complete cure.Conclusion
Bacillus species can cause clinically significant central venous catheter infection, even in an immunocompetent host. Despite adequate antibiotic treatment, the central venous catheter may need removal for complete cure. 相似文献44.
Werther Guidi Nissim Hafssa Kadri Frederic E. Pitre 《International journal of phytoremediation》2015,17(8):745-752
In this preliminary screening study, we tested the phytoextraction potential of nine Canadian native/well-adapted plant species on a soil highly polluted by trace elements (TE) from a copper refinery. Plant physiological parameters and soil cover index were monitored for a 12-week period. At the end of the trial, biomass yield, bioconcentration (BFC) and translocation (TF) factors for the main TE as well as phytoextraction potential were determined. Most plants were severely injured by the high pollution levels, showing symptoms of toxicity including chlorosis, mortality and very low biomass yield. However, Indian mustard showed the highest selenium extraction potential (65 mg m?2), even under harsh growing conditions. Based on our results, tall fescue and ryegrass, which mainly stored As, Cu, Pb and Zn within roots, could be used effectively for phytostabilization. 相似文献
45.
CA Siegrist C van Delden M Bel C Combescure C Delhumeau M Cavassini O Clerc S Meier K Hadaya PM Soccal S Yerly L Kaiser B Hirschel A Calmy;HN Study Group;Swiss HIV Cohort Study 《PloS one》2012,7(7):e40428
Background
Memory responses require immune competence. We assessed the influence of priming with AS03-adjuvanted pandemic vaccine (Pandemrix®) on memory responses of HIV patients, kidney recipients (SOT) and healthy controls (HC).Method
Participants (HIV: 197, SOT: 53; HC: 156) were enrolled in a prospective study and 390/406 (96%) completed it. All had been primed in 2009/2010 with 1 (HC) or 2 (patients) doses of Pandemrix®, and were boosted with the 2010/2011 seasonal influenza vaccine. Geometric mean titres and seroprotection rates were measured 12 months after priming and 4 weeks after boosting. Primary and memory responses were directly compared in 191 participants (HCW: 69, HIV: 71, SOT: 51) followed during 2 consecutive seasons.Results
Most participants (HC: 77.8%, HIV: 77.6%, SOT: 66%) remained seroprotected at 12 months post-priming. Persisting A/09/H1N1 titers were high in HIV (100.2) and HC (120.1), but lower in SOT (61.4) patients. Memory responses reached higher titers in HIV (507.8) than in HC (253.5) and SOT (136.9) patients. Increasing age and lack of HAART reduced persisting and memory responses, mainly influenced by residual antibody titers. Comparing 2009/2010 and 2010/2011 titers in 191 participants followed for 2 seasons indicated lower post-2010/2011 titers in HC (240.2 vs 313.9), but higher titers in HIV (435.7 vs 338.0) and SOT (136 vs 90.3) patients.Conclusions
Priming with 2 doses of Pandemrix® elicited persistent antibody responses and even stronger memory responses to non-adjuvanted seasonal vaccine in HIV patients than 1 dose in healthy subjects. Adjuvanted influenza vaccines may improve memory responses of immunocompromised patients.Trial Registration
ClinicalTrials.gov NCT01022905相似文献46.
The intermediate filament protein synemin is present in astrocyte progenitors and glioblastoma cells but not in mature astrocytes. Here we demonstrate a role for synemin in enhancing glioblastoma cell proliferation and clonogenic survival, as synemin RNA interference decreased both behaviors by inducing G1 arrest along with Rb hypophosphorylation and increased protein levels of the G1/S inhibitors p21(Cip1) and p27(Kip1). Akt involvement was demonstrated by decreased phosphorylation of its substrate, p21(Cip1), and reduced Akt catalytic activity and phosphorylation at essential activation sites. Synemin silencing, however, did not affect the activities of PDPK1 and mTOR complex 2, which directly phosphorylate Akt activation sites, but instead enhanced the activity of the major regulator of Akt dephosphorylation, protein phosphatase type 2A (PP2A). This was accompanied by changes in PP2A subcellular distribution resulting in increased physical interactions between PP2A and Akt, as shown by proximity ligation assays (PLAs). PLAs and immunoprecipitation experiments further revealed that synemin and PP2A form a protein complex. In addition, treatment of synemin-silenced cells with the PP2A inhibitor cantharidic acid resulted in proliferation and pAkt and pRb levels similar to those of controls. Collectively these results indicate that synemin positively regulates glioblastoma cell proliferation by helping sequester PP2A away from Akt, thereby favoring Akt activation. 相似文献
47.
FRANK BAUMANN JIN-SHENG HE† KARSTEN SCHMIDT PETER KÜHN THOMAS SCHOLTEN 《Global Change Biology》2009,15(12):3001-3017
We investigated the main parameters [e.g. mean annual air temperature , mean annual soil temperature, mean annual precipitation, soil moisture (SM), soil chemistry, and physics] influencing soil organic carbon (Corg), soil total nitrogen (Nt) as well as plant available nitrogen (Nmin) at 47 sites along a 1200 km transect across the high‐altitude and low‐latitude permafrost region of the central‐eastern Tibetan Plateau. This large‐scale survey allows testing the hypothesis that beside commonly used ecological variables, diversity of pedogenesis is another major component for assessing carbon (C) and nitrogen (N) cycling. The aim of the presented research was to evaluate consequences of permafrost degradation for C and N stocks and hence nutrient supply for plants, as the transect covers all types of permafrost including heavily degraded areas and regions without permafrost. Our results show that SM is the dominant parameter explaining 64% of Corg and 60% of N variation. The extent of the effect of SM is determined by permafrost, current aeolian sedimentation occurring mostly on degraded sites, and pedogenesis. Thus, the explanatory power for C and N concentrations is significantly improved by adding CaCO3 content (P=0.012 for Corg; P=0.006 for Nt) and soil texture (P=0.077 for Corg; P=0.015 for Nt) to the model. For soil temperature, no correlations were detected indicating that in high‐altitude grassland ecosystems influenced by permafrost, SM overrides soil temperature as the main driving parameter at landscape scale. It was concluded from the current study that degradation of permafrost and corresponding changes in soil hydrology combined with a shift from mature stages of pedogenesis to initial stages, have severe impact on soil C and plant available N. This may alter biodiversity patterns as well as the development and functioning of the ecosystems on the Tibetan Plateau. 相似文献
48.
BACKGROUND: Urinary bladder dysfunction is a complication in diabetes but the mechanisms involved are undefined. Here, we investigated roles of oxidative stress and oxidant driven signaling pathways in a murine model of diabetes, with an emphasis on urothelial vs. smooth muscle regional changes. METHODS: Mice were dosed with streptozotocin (150 mg/kg) or vehicle and studied at 5 weeks. Functional changes were assessed by in vitro cystometry. Immunohistochemical methods and automated digital imaging was used for morphometric and histochemical analysis of bladder tissue regions. RESULTS: We detected significant increases in protein 3-nitrotyrosine in both urothelium and smooth muscle regions during diabetes, demonstrating an increased prevalence of reactive nitrogen species. In light of nitric oxide synthase (NOS) isoforms as potential contributors to increased protein nitration, all three NOS isoforms were studied; region specific increases in NOS1 (urothelium and smooth muscle), NOS2 (urothelium only) but no alterations in NOS3 isoform were detected during diabetes. In contrast, p21-Rac1 (coordinating protein of NADPH oxidase) was significantly increased only in smooth muscle (diabetic vs. controls). We also investigated phosphorylation of ERK, JNK, p38 and Akt using immunohistochemical techniques; each of these was increased during diabetes but with different distributions in the two major regions of bladder tissues viz the smooth muscle and urothelium. CONCLUSIONS: The STZ mouse model of diabetes exhibits bladder dysfunction and structural changes similar to human. Reactive nitrogen species formation occurs in this setting and region specific assessments also revealed that urothelial changes and smooth muscle changes are discrete with respect to mechanisms of reactive nitrogen species (increased production of NO vs. superoxide anion) and activation of oxidant related stress signaling pathways. 相似文献
49.
Predation by a predator complex consisting of adults of the lygaeidGeocoris punctipes (Say), the nabidsNabis roseipennis Reuter and/orTropiconabis capsiformis Germar and the coccinelids,Hippodamia convergens Guerin-Meneville andColeomegilla maculata (DeGeer) onHeliothis virescens (F.) eggs, 1st-instar larvae or both on late pinhead square and early bloom stage cotton was evaluated in field cages in
Mississippi. Prey densities of 4 (11, 512/ha) or 8 per cage and predator: prey (P:p) ratios of 1∶1, 2∶1, 3∶1, 4∶1 and 5∶1
were used. Prey were labeled with phosphorus-32 or carbon-14 to determine predator ingestion and effectiveness. Average percent
egg predation as a function of P:p ratio ranged from 2.1 to 12.1 for a 48 h period. The average percent predation on larvae
as a function of P:p ratio ranged from 5.3 to 22.0. The hemiptera fed more than the coleoptera on larvae, andG. punctipes was the best egg predator. For the range of predator densities used, the average area of discovery for the predator complex
was 6.98 × 10−3 m/day and 2.34 × 10−2 m/day when exposed to eggs and larvae, respectively.
Publication No 5936-Mississippi Agricultural and Forestry Experiment Station, Mississippi State, MS 39762. 相似文献
50.
MOTIVATION: Recently, we described a Maximum Weighted Matching (MWM) method
for RNA structure prediction. The MWM method is capable of detecting
pseudoknots and other tertiary base-pairing interactions in a
computationally efficient manner (Cary and Stormo, Proceedings of the Third
International Conference on Intelligent Systems for Molecular Biology, pp.
75-80, 1995). Here we report on the results of our efforts to improve the
MWM method's predictive accuracy, and show how the method can be extended
to detect base interactions formerly inaccessible to automated RNA modeling
techniques. RESULTS: Improved performance in MWM structure prediction was
achieved in two ways. First, new ways of calculating base pair likelihoods
have been developed. These allow experimental data and combined statistical
and thermodynamic information to be used by the program. Second, accuracy
was improved by developing techniques for filtering out spurious base pairs
predicted by the MWM program. We also demonstrate here a means by which the
MWM folding method may be used to detect the presence of base triples in
RNAs. AVAILABILITY: http://www.cshl.org/mzhanglab/tabaska/j axpage. html
CONTACT: tabaska@cshl.org
相似文献