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81.
82.
Alpha-dendrotoxin acceptor from bovine brain is a K+ channel protein. Evidence from the N-terminal sequence of its larger subunit 总被引:4,自引:0,他引:4
V E Scott D N Parcej J N Keen J B Findlay J O Dolly 《The Journal of biological chemistry》1990,265(33):20094-20097
High affinity acceptors for alpha-dendrotoxin, a selective probe for certain fast activating voltage-dependent K+ channels, were purified approximately 4,000-fold from synaptic plasma membranes of bovine cerebral cortex. Although the preparation possessed a low content of high affinity sites for beta-bungarotoxin, antagonism of alpha-dendrotoxin binding by the latter required high concentrations; this indicates that more than one acceptor subtype has been purified. After deglycosylation of the acceptor, the sizes of its subunits were determined electrophoretically to be Mr 65,000 and Mr 39,000. Solid phase microsequencing of these isolated subunits showed that the smaller one had a blocked N terminus, but the Mr 65,000 protein gave a sequence of 27 residues. This is virtually identical to the N-terminal sequence deduced from cDNA of RCK 5, a K+ channel protein from rat brain known to be susceptible to alpha-dendrotoxin. This first report on the partial sequence of any K+ channel protein confirms that the extensive information acquired to date on the alpha-dendrotoxin acceptors is pertinent to functional neuronal K+ channels. 相似文献
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Sleep and Biological Rhythms - Deciphering the significance of dreams, remains a dream till date. A little is known about its underlying mechanism, brain regions involved and implications with wake... 相似文献
85.
Dolan Thomas J Hatcher CP Satterfield DA Theodore MJ Bach MC Linscott KB Zhao X Wang X Mair R Schmink S Arnold KE Stephens DS Harrison LH Hollick RA Andrade AL Lamaro-Cardoso J de Lemos AP Gritzfeld J Gordon S Soysal A Bakir M Sharma D Jain S Satola SW Messonnier NE Mayer LW 《PloS one》2011,6(5):e19361
Real-time PCR (rt-PCR) is a widely used molecular method for detection of Neisseria meningitidis (Nm). Several rt-PCR assays for Nm target the capsule transport gene, ctrA. However, over 16% of meningococcal carriage isolates lack ctrA, rendering this target gene ineffective at identification of this sub-population of meningococcal isolates. The Cu-Zn superoxide dismutase gene, sodC, is found in Nm but not in other Neisseria species. To better identify Nm, regardless of capsule genotype or expression status, a sodC-based TaqMan rt-PCR assay was developed and validated. Standard curves revealed an average lower limit of detection of 73 genomes per reaction at cycle threshold (C(t)) value of 35, with 100% average reaction efficiency and an average R(2) of 0.9925. 99.7% (624/626) of Nm isolates tested were sodC-positive, with a range of average C(t) values from 13.0 to 29.5. The mean sodC C(t) value of these Nm isolates was 17.6±2.2 (±SD). Of the 626 Nm tested, 178 were nongroupable (NG) ctrA-negative Nm isolates, and 98.9% (176/178) of these were detected by sodC rt-PCR. The assay was 100% specific, with all 244 non-Nm isolates testing negative. Of 157 clinical specimens tested, sodC detected 25/157 Nm or 4 additional specimens compared to ctrA and 24 more than culture. Among 582 carriage specimens, sodC detected Nm in 1 more than ctrA and in 4 more than culture. This sodC rt-PCR assay is a highly sensitive and specific method for detection of Nm, especially in carriage studies where many meningococcal isolates lack capsule genes. 相似文献
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Effects of mute swan grazing on a keystone macrophyte 总被引:2,自引:0,他引:2
MATTHEW T. O'HARE RICHARD A. STILLMAN JO MCDONNELL LAURA R. WOOD 《Freshwater Biology》2007,52(12):2463-2475
1. This study describes the early summer foraging behaviour of mute swans (Cygnus olor) on the River Frome, a highly productive chalk stream in southern England in which Ranunculus penicillatus pseudofluitans is the dominant macrophyte. 2. A daily maximum of 41 ± 2.5 swans were present along the 1.1 km study reach during the study period (late May to the end of June). The river was the primary feeding habitat. Feeding activity on the river at dawn and dusk was much lower than during daylight, but we cannot rule out the possibility that swans fed during the hours of darkness. 3. The effects of herbivory on R. pseudofluitans biomass and morphology were quantified. Biomass was lower in grazed areas and swans grazed selectively on leaves in preference to stems. A lower proportion of stems from grazed areas possessed intact stem apices and flowering of the plant was reduced in grazed areas. 4. A model, based on the swans’ daily consumption, was used to predict the grazing pressure of swans on R. pseudofluitans. The model accurately predicted the number of bird days supported by the study site, only if grazing was assumed to severely reduce R. pseudofluitans growth. The proportion of the initial R. pseudofluitans biomass consumed by a fixed number of swans was predicted to be greater when the habitat area was smaller, initial R. pseudofluitans biomass was lower and R. pseudofluitans was of lower food value. 5. We concluded that the flux of N and P through the study reach was largely unaffected by swan activity. The quality of R. pseudofluitans mesohabitat (the plant as habitat for invertebrates and fish) was significantly reduced by grazing which also indirectly contributed to reduced roughness (Manning's n) and by inference water depth. Wetted habitat area for fish and invertebrates would also be lowered over the summer period as a consequence of the reduction in water depth. It was estimated that, while grazing, an individual swan may eat the same mass of invertebrates per day as a 300‐g trout. 6. There is a need to manage the conflict between mute swans and the keystone macrophyte, R. pseudofluitans, in chalk streams, and the modelling approach used here offers a potentially useful tool for this purpose. 相似文献
88.
Shiradkar MR Murahari KK Gangadasu HR Suresh T Kalyan CA Panchal D Kaur R Burange P Ghogare J Mokale V Raut M 《Bioorganic & medicinal chemistry》2007,15(12):3997-4008
In the present study, a series of N-{4-[(4-amino-5-sulfanyl-4H-1,2,4-triazol-3-yl)methyl]-1,3-thiazol-2-yl}-2-substituted-amide (1a-d) derivatives were synthesized in good yields and characterized by IR, 1H NMR, mass spectral and elemental analyses. The compounds were evaluated for their preliminary in vitro antibacterial activity against Staphylococcus aureus, Escherichia coli, Pseudomonas aeruginosa and Salmonella typhosa and then were screened for antitubercular activity against Mycobacterium tuberculosis H37 Rv strain by broth microdilution assay method. The antibacterial data of the tested compounds indicated that most of the synthesized compounds showed better activity against bacteria compared to reference drugs. The in vitro antitubercular activity reports of tested compounds against M. tuberculosis strain H37 Rv showed moderate to better activity. 相似文献
89.
Combinatorial methods in molecular imprinting 总被引:4,自引:0,他引:4
Molecular imprinting is a general method for synthesizing robust, network polymers with highly specific binding sites for small molecules. Recently, combinatorial and computational approaches have been employed to select an optimal molecularly imprinted polymer (MIP) formulation for a targeted analyte. The use of MIPs in the combinatorial field, specifically their use for screening libraries of small molecules, has also been developed. 相似文献
90.
POLYANNA DA CONCEIÇÃO BISPO MÁRCIO DE MORISSON VALERIANO JOÃO ROBERTO DOS SANTOS 《Austral ecology》2012,37(4):491-499
The objective of this study was to identify the effects of local geomorphometry on the abundance, richness and floristic composition of tree species in the central Brazilian Amazon. Forty‐six 0.25‐ha plots in different phyto‐ecologic sites were sampled, and their trees were inventoried. Geomorphometric data (elevation, slope, aspect, plan and profile curvatures) were derived from Shuttle Radar Topography Mission data. A detrended correspondence analysis (DCA) was used to examine the floristic distribution patterns among plots. In addition, geomorphometric variables were submitted to multiple regression analysis to identify the variables influencing floristic composition (represented by the first DCA component), abundance and species richness. Correlation analyses between the number of individuals from each species and the first DCA component were performed to evaluate the contribution of each species. Analysis of the results could not confirm an effect of geomorphometry alone on species richness and abundance, although floristic composition was significantly influenced by profile curvature and elevation. Despite the relatively low variation in altitude at the study site, species were found to be sensitive to terrain peculiarities such as elevation and profile curvature, which can constrain particular ecologic niches and contribute to the spatial distribution patterns of species. 相似文献