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排序方式: 共有91条查询结果,搜索用时 31 毫秒
1.
Fokko J. Bosker Tessa Y. C. E. de Winter ré A. Klompmakers Herman G. M. Westenberg 《Journal of neurochemistry》1996,66(6):2546-2555
Abstract: The effects of systemic administration of the serotonin (5-hydroxytryptamine) 5-HT1A receptor agonists flesinoxan and 8-hydroxy-2-(di- n -propylamino)tetralin on extracellular 5-HT were measured using microdialysis probes in both median raphe nucleus and dorsal hippocampus. Both 5-HT1A agonists dose-dependently decreased dialysate 5-HT levels from both brain regions. The effects of flesinoxan in the median raphe (0.3 mg/kg) and dorsal hippocampus (1.0 mg/kg) could be blocked by the 5-HT1A receptor antagonist N -[2-[4-(2-methoxyphenyl)-1-piperazinyl]ethyl]- N -(2-pyridyl)cyclohexane carboxamide trihydrochloride (WAY 100,635) at a dose of 0.05 mg/kg s.c. The antagonist itself had no effect at this dosage. Local perfusion of flesinoxan for 30 min through the dialysis probe into the median raphe region at concentrations of 20, 100, and 1,000 n M resulted in a significant decrease in dialysate 5-HT content from both regions. The effect of 100 n M flesinoxan could be blocked by coperfusion of 1,000 n M WAY 100,635. The data indicate that flesinoxan is a potent 5-HT1A receptor agonist and also support the notion that somatodendritic 5-HT1A autoreceptors regulate both terminal and somatodendritic 5-HT release. 相似文献
2.
mtDNA diversity in rhesus monkeys reveals overestimates of divergence time and paraphyly with neighboring species 总被引:4,自引:0,他引:4
Reconstructions of the human-African great ape phylogeny by using
mitochondrial DNA (mtDNA) have been subject to considerable debate. One
confounding factor may be the lack of data on intraspecific variation. To
test this hypothesis, we examined the effect of intraspecific mtDNA
diversity on the phylogenetic reconstruction of another Plio- Pleistocene
radiation of higher primates, the fascicularis group of macaque (Macaca)
monkey species. Fifteen endonucleases were used to identify 10 haplotypes
of 40-47 restriction sites in M. mulatta, which were compared with similar
data for the other members of this species group. Interpopulational,
intraspecific mtDNA diversity was large (0.5%- 4.5%), and estimates of
divergence time and branching order incorporating this variation were
substantially different from those based on single representatives of each
species. We conclude that intraspecific mtDNA diversity is substantial in
at least some primate species. Consequently, without prior information on
the extent of genetic diversity within a particular species, intraspecific
variation must be assessed and accounted for when reconstructing primate
phylogenies. Further, we question the reliability of hominoid mtDNA
phylogenies, based as they are on one or a few representatives of each
species, in an already depauperate superfamily of primates.
相似文献
3.
Electron transfer from menaquinol to fumarate. Fumarate reductase anchor polypeptide mutants of Escherichia coli 总被引:3,自引:0,他引:3
D J Westenberg R P Gunsalus B A Ackrell G Cecchini 《The Journal of biological chemistry》1990,265(32):19560-19567
Fumarate reductase (FRD) of Escherichia coli is a four-subunit membrane-bound complex that is synthesized during anaerobic growth when fumarate is available as a terminal oxidant. The two subunits that comprise the catalytic domain, FrdA and FrdB, are anchored to the cytoplasmic membrane surface by two small hydrophobic polypeptides, FrdC and FrdD, which are also required for the enzyme to interact with quinone. To better define the individual roles of the FrdC and FrdD polypeptides in FRD complex formation and quinone binding, we selectively mutagenized the frdCD genes. Frd- strains were identified by their inability to grow on restrictive media, and the resulting mutant FRD complexes were isolated and biochemically characterized. The majority of the frdC and frdD mutations were identified as single base deletions that caused premature termination in either FrdC or FrdD and resulted in the loss of one or more of the predicted transmembrane helices. Two additional frdC mutants were characterized that contained single base changes resulting in single amino acid substitutions. All mutant enzyme complexes were incapable of oxidizing the physiological electron donor, menaquinol-6, in the presence of fumarate. Additionally, the ability of the mutant complexes to oxidize reduced benzyl viologen or reduce the ubiquinone analogue 2,3-dimethoxy-5-methyl-6-pentyl-1,4-benzoquinone and phenazine methosulfate with succinate as electron donor were also affected but to varying degrees. The separation of oxidative and reductive activities with quinones suggests there are two quinone binding sites in the fumarate reductase complex and that electron transfer occurs in two le- steps carried out at these separate sites. 相似文献
4.
Acta Biotheoretica - 相似文献
5.
Schneiderheinze JM Armstrong DW Schulte G Westenberg DJ 《FEMS microbiology letters》2000,192(1):39-44
Recent advances in the technique of capillary electrophoresis have demonstrated fast, highly efficient separation of mixtures of intact microbes. This paper describes the application of this technique for the separation of microbial aggregates of Micrococcus luteus, Saccharomyces cerevisiae, or Alcaligenes faecalis. The aggregates of these microbes were resolved into several highly efficient peaks with analysis times under 10 min and efficiencies approaching 1000000 plates m(-1) in some cases. A reproducible relationship was found between the electrophoretic mobility and the aggregation number or size of the cluster under a given set of experimental conditions. Often, cellular aggregation was reversible with brief immersion in an ultrasound bath. This reversibility was confirmed by visual microscopy and electrophoretic data. 相似文献
6.
Muma JB Lund A Siamudaala VM Munang'andu HM Munyeme M Matope G Nielsen K DJønne B Godfroid J Tryland M Skjerve E 《Journal of wildlife diseases》2010,46(4):1063-1069
One of the diseases of veterinary and public health importance affecting the Kafue lechwe (Kobus leche kafuensis) on the Kafue flats is brucellosis, for which only scant information is available. During the 2003 (October), 2004 (December), and 2008 (July-December) hunting seasons in the Kafue flats, we conducted a study to determine the seroprevalence of Brucella spp. in the Kafue lechwe and to evaluate serologic tests for detection of Brucella spp. antibodies in lechwe. The Rose Bengal Test (RBT), competitive enzyme-linked immunosorbent assay (cELISA), and fluorescence polarization assay (FPA) were used. A total of 121 Kafue lechwe were hunted for disease investigations in 2003, 2004, and 2008 in the Kafue Flat Game Management Area. Of these, 21.6%, (95% confidence interval [CI]: 14.2-29.1%) had detectable antibodies to Brucella spp. The Kafue lechwe in Lochnivar National Park had higher antibody results than those in Blue Lagoon National Park (odds ratio=3.0; 95% CI: 0.94-9.4). Infection levels were similar in females (21.6%) and males (21.7%). Results were similar among RBT, FPA, cELISA tests, suggesting that these could effectively be used in diagnosing brucellosis in the Kafue lechwe. Our study demonstrates the presence of Brucella infections in the Kafue lechwe in two national parks located in the Kafue flats and further highlights the suitability of serologic assays for testing the Kafue lechwe. Because the Kafue lechwe is the most hunted wildlife species in Zambia, hunters need to be informed of the public health risk of Brucella spp. infection. 相似文献
7.
Marcel Westenberg Sophie Bamps Helen Soedling Ian A Hope Colin T Dolphin 《BMC biotechnology》2010,10(1):27
Background
Escherichia coli strain EL350 contains chromosomally integrated phage lambda Red recombinase genes enabling this strain to be used for modifying the sequence of resident clones via recombineering. BAC and fosmid clones are highly suitable for modification by recombineering but, because they are present at low (1-2) copies per cell, the DNA is difficult to isolate in high yield and purity. To overcome this limitation vectors, e.g. pCC1FOS, have been constructed that contain the additional replication origin, oriV, which permits copy-number to be induced transiently when propagated in a suitable host strain, e.g. EPI300, that supplies the cognate trans -replication protein TrfA. Previously, we used EL350 and EPI300 sequentially to recombineer oriV -equipped fosmid genomic clones and, subsequently, to induce copy-number of the resulting recombinant clone. To eliminate these intervening DNA isolation and transformation steps we retrofitted EL350 with a P BAD-driven trfA gene generating strain MW005 that supports, independently, both recombineering and copy-number induction. 相似文献8.
Susan DJ Chapple Anna M Crofts S Paul Shadbolt John McCafferty Michael R Dyson 《BMC biotechnology》2006,6(1):49-15
Background
A variety of approaches to understanding protein structure and function require production of recombinant protein. Mammalian based expression systems have advantages over bacterial systems for certain classes of protein but can be slower and more laborious. Thus the availability of a simple system for production and rapid screening of constructs or conditions for mammalian expression would be of great benefit. To this end we have coupled an efficient recombinant protein production system based on transient transfection in HEK-293 EBNA1 (HEK-293E) suspension cells with a dot blot method allowing pre-screening of proteins expressed in cells in a high throughput manner. 相似文献9.
Luykx JJ Bakker SC Lentjes E Boks MP van Geloven N Eijkemans MJ Janson E Strengman E de Lepper AM Westenberg H Klopper KE Hoorn HJ Gelissen HP Jordan J Tolenaar NM van Dongen EP Michel B Abramovic L Horvath S Kappen T Bruins P Keijzers P Borgdorff P Ophoff RA Kahn RS 《PloS one》2012,7(2):e30497
Background
Animal studies have revealed seasonal patterns in cerebrospinal fluid (CSF) monoamine (MA) turnover. In humans, no study had systematically assessed seasonal patterns in CSF MA turnover in a large set of healthy adults.Methodology/Principal Findings
Standardized amounts of CSF were prospectively collected from 223 healthy individuals undergoing spinal anesthesia for minor surgical procedures. The metabolites of serotonin (5-hydroxyindoleacetic acid, 5-HIAA), dopamine (homovanillic acid, HVA) and norepinephrine (3-methoxy-4-hydroxyphenylglycol, MPHG) were measured using high performance liquid chromatography (HPLC). Concentration measurements by sampling and birth dates were modeled using a non-linear quantile cosine function and locally weighted scatterplot smoothing (LOESS, span = 0.75). The cosine model showed a unimodal season of sampling 5-HIAA zenith in April and a nadir in October (p-value of the amplitude of the cosine = 0.00050), with predicted maximum (PCmax) and minimum (PCmin) concentrations of 173 and 108 nmol/L, respectively, implying a 60% increase from trough to peak. Season of birth showed a unimodal 5-HIAA zenith in May and a nadir in November (p = 0.00339; PCmax = 172 and PCmin = 126). The non-parametric LOESS showed a similar pattern to the cosine in both season of sampling and season of birth models, validating the cosine model. A final model including both sampling and birth months demonstrated that both sampling and birth seasons were independent predictors of 5-HIAA concentrations.Conclusion
In subjects without mental illness, 5-HT turnover shows circannual variation by season of sampling as well as season of birth, with peaks in spring and troughs in fall. 相似文献10.