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51.
Sambuddha Banerjee Aurkie Ray Soma Sen Samiran Mitra David L. Hughes Ray J. Butcher Stuart R. Batten David R. Turner 《Inorganica chimica acta》2008,361(9-10):2692-2700
The effects of pseudohalides on the modes of binding of a hydrazone ligand are investigated and we report here four new hydrazone complexes [Co(L)2] · ClO4 (1), [Co(L)2]2[Co(SCN)4] (2), [Mn(L)2] (3) and [Mn(N3)2 (LH)2] · H2O (4) [where LH = condensation product of pyridine-2-carboxaldehyde and benzhydrazide]. The hydrazone ligand is quite diverse in its chelating ability and can act as a neutral or mononegative ligand and as a bidentate or tridentate unit. In this paper, we report structures showing different denticities of the ligand having different charges. The complexes are characterized by IR, UV–Vis spectroscopy and cyclic voltammetric studies and the structures are conclusively established by single crystal X-ray diffraction study. Of the complexes, 1 and 3 are purely metal hydrazone complexes whereas 2 and 4 incorporate coordinated pseudohalides in their crystal structures, and 4 shows different coordination modes of the hydrazone ligand. 相似文献
52.
A 14-year-old boy with severe asthma was treated with prednisone and disodium cromoglycate with considerable subjective improvement, though there was persistent airways obstruction. After several weeks'' freedom from symptoms he died in a severe attack of nocturnal asthma. Necropsy findings suggested that hypersecretion had been occurring in die medium-sized airways for several days before death. 相似文献
53.
54.
L. A. Batten 《Bird Study》2013,60(3):157-164
Inland roosts did not show increased numbers during spring migration, and midsummer roosts of non-breeders proved less extensive than had been supposed 相似文献
55.
Rachael?C. Wilkinson Laura?E. Batten Neil?J. Wells Petra?C.F. Oyston Peter?L. Roach 《Bioscience reports》2015,35(6)
The bacterial stringent response is induced by nutrient deprivation and is mediated by enzymes of the RSH (RelA/SpoT homologue; RelA, (p)ppGpp synthetase I; SpoT, (p)ppGpp synthetase II) superfamily that control concentrations of the ‘alarmones’ (p)ppGpp (guanosine penta- or tetra-phosphate). This regulatory pathway is present in the vast majority of pathogens and has been proposed as a potential anti-bacterial target. Current understanding of RelA-mediated responses is based on biochemical studies using Escherichia coli as a model. In comparison, the Francisella tularensis RelA sequence contains a truncated regulatory C-terminal region and an unusual synthetase motif (EXSD). Biochemical analysis of F. tularensis RelA showed the similarities and differences of this enzyme compared with the model RelA from Escherichia coli. Purification of the enzyme yielded a stable dimer capable of reaching concentrations of 10 mg/ml. In contrast with other enzymes from the RelA/SpoT homologue superfamily, activity assays with F. tularensis RelA demonstrate a high degree of specificity for GTP as a pyrophosphate acceptor, with no measurable turnover for GDP. Steady state kinetic analysis of F. tularensis RelA gave saturation activity curves that best fitted a sigmoidal function. This kinetic profile can result from allosteric regulation and further measurements with potential allosteric regulators demonstrated activation by ppGpp (5′,3′-dibisphosphate guanosine) with an EC50 of 60±1.9 μM. Activation of F. tularensis RelA by stalled ribosomal complexes formed with ribosomes purified from E. coli MRE600 was observed, but interestingly, significantly weaker activation with ribosomes isolated from Francisella philomiragia. 相似文献
56.
Robyn Manley Lara E. Harrup Eva Veronesi Francesca Stubbins Jo Stoner Simon Gubbins Anthony Wilson Carrie Batten Constantianus J. M. Koenraadt Mark Henstock James Barber Simon Carpenter 《PloS one》2015,10(8)
Background
Schmallenberg virus (SBV), an arboviral pathogen of ruminants, emerged in northern Europe during 2011 and has subsequently spread across a vast geographic area. While Culicoides biting midges (Diptera: Ceratopogonidae) have been identified as a biological transmission agent of SBV, the role of mosquitoes (Diptera: Culicidae) as potential vectors has not been defined beyond small-scale field collections in affected areas. Culex pipiens L. are one of the most widespread mosquitoes in northern Europe; they are present on farms across the region and have previously been implicated as vectors of several other arboviruses. We assessed the ability of three colony lines of Cx. pipiens, originating from geographically diverse field populations, to become fully infected by SBV using semi-quantitative real-time RT-PCR (sqPCR).Findings
Two colony lines of Cx. pipiens were created in the UK (‘Brookwood’ and ‘Caldbeck’) from field collections of larvae and pupae and characterised using genetic markers. A third strain of Cx. pipiens from CVI Wageningen, The Netherlands, was also screened during experiments. Intrathoracic inoculation of the Brookwood line resulted in infections after 14 days that were characterised by high levels of RNA throughout individuals, but which demonstrated indirect evidence of salivary gland barriers. Feeding of 322 individuals across the three colony lines on a membrane based infection system resulted in no evidence of full dissemination of SBV, although infections did occur in a small proportion of Cx. pipiens from each line.Conclusions/Significance
This study established two novel lines of Cx. pipiens mosquitoes of UK origin in the laboratory and subsequently tested their competence for SBV. Schmallenberg virus replication and dissemination was restricted, demonstrating that Cx. pipiens is unlikely to be an epidemiologically important vector of the virus in northern Europe. 相似文献57.
Soil Microbial Community Associated with an Invasive Grass Differentially Impacts Native Plant Performance 总被引:1,自引:0,他引:1
This study is one of the first to show that invasive plant-induced changes in the soil microbial community can negatively
impact native plant performance. This greenhouse experiment tested whether soil microbial communities specific to the rhizospheres
of an invasive grass (Aegilops triuncialis) and two native plants (Lasthenia californica and Plantago erecta) affected invasive and/or native plant performance. Each of these species were grown in separate pots for 2 months to prime
the soils with plant-specific rhizosphere microbial communities. Each plant species was then planted in native- and invasive-primed
soil, and effects on plant performance were monitored. At 5 months, differences in microbial biomarker fatty acids between
invaded and native soils mirrored previous differences found in field-collected soil. L. californica performance was significantly reduced when grown in invaded soil compared to native soil (flowering date was delayed, aboveground
biomass decreased, specific root length increased, and root mass ratio increased). In contrast, P. erecta and A. triuncialis performance were unaffected when grown in invaded vs native soil. These results suggest that in some cases, invasion-induced
changes in the soil microbial community may contribute to a positive feedback loop, leading to the increased dominance of
invasive species in an ecosystem. 相似文献
58.
Summary Using the PAP unlabelled antibody method, LH, FSH, TSH and ACTH were localized at light microscope level in cultured cells dissociated from the porcine adenohypophysis. Antisera were shown to be specific for the subunits of the porcine glycoprotein hormones by radioimmunoassay and absorption studies. Using these antisera, it was found that LH and FSH were contained within the same cell, with TSH in a separate cell. When absorbed with LH, anti-porcine ACTH stained a separate distinct population of ACTH cells.Adjacent ultra-thin sections stained with anti-pLH and anti-pFSH, and examined at electron microscope level, showed that the ovoid, 150–400 nm secretory granules of the LH/FSH gonadotrophs contained both LH and FSH.The authors gratefully acknowledge the technical assistance of Carole Smith and Adrian Walsh 相似文献
59.
The effects of a maternal injection of trypan blue on primitive streak mouse embryos were studied with electron microscopy. Commercial trypan blue was purified by descending paper chromatography, and pregnant females received an intraperitoneal injection of the collected blue fraction on the evening of the 7th day of gestation. Ultrastructurally, the changes in the visceral endoderm were apparent 10 min after the injection and included an increase in the number of fuzzy-coated vesicles in the apical cytoplasm. By 20 min the apical cytoplasm of the extraembryonic visceral endodermal cells was filled with many fuzzy-coated vesicles and numerous vacuoles of various size and electron density. 30 min after the injection, the extraembryonic visceral endodermal cells were relatively smooth lacking a microvillous border and evidence of endocytic activity was rare. Many embryonic visceral endodermal cells were observed in various stages of degeneration although the underlying embryonic ectoderm appeared unaffected. Morphologically, it appears that trypan blue exerts its first effect by altering the endocytic activity of the visceral endoderm. 相似文献
60.
A series of Ni(II) and Cu(II) complexes of the hexaaza macrocycles, 3,6,9,17,20,23-hexaazatricyclo[23.3.1.111,15]triaconta-1(29),11(30),12,14,25,27-hexaene (L1) and 3,6,9,16,19,22-hexaazatricyclo[22.2.2.211,14]triaconta-1(26),11(29),12,14(30),24(28),25-hexaene (L2), have been prepared and the crystal structures determined for [Ni2L1(O2CCH3)2(H2O)2](ClO4)2 (1), [Ni2L2(DMF)6](ClO4)4 · 2H2O (2), {[Cu2L2Br(O2CCH3)](ClO4)2}n (3), [Cu2L2(μ-CO3)(H2O)2]2(ClO4)4 · 8H2O (4), [Cu2L2(O2CCH3)2](BF4)2 (5), and [Cu2L1(μ-imidazolate)Br]2Br4 · 6H2O (6). In these complexes, two metal centers are bound per ligand; in 1 and 3-6, the N3 subunits of L1 or L2 coordinate meridionally to the metal centers, whilst in 2, each N3 subunit in L2 adopts a facial mode of coordination. The binuclear cations in 1 and 2 have chair-like conformations, with the distorted octahedral Ni(II) coordination spheres completed by terminal water and a bidentate acetate ligand in 1 and three DMF ligands in 2. The Cu(II) centers in 3-6 generally reside in square planar environments, although a weakly binding ligand enters the coordination sphere in some cases, generating a distorted square pyramidal geometry. The binuclear [Cu2L2]4+ units in 3, 4 and 5 adopt similar bowl-shaped conformations, stabilized by H-bonding interactions between pairs of amine groups from L2 and a perchlorate or tetrafluoroborate anion. In 3, the binuclear units are linked through acetate groups, bridging in a syn-anti fashion, to produce a zig-zag polymeric chain structure, whilst 4 incorporates a tetrameric cation consisting of two binuclear units linked via a pair of carbonate bridges. Compound 6 features an imidazolate bridge between the two Cu(II) centers bound by L1. Pairs of [Cu2L1(μ-imidazolate)]3+ units are then weakly linked through a pair of bromide anions. 相似文献