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1.
Isolation of genes encoding the Neurospora vacuolar ATPase. Analysis of vma-1 encoding the 67-kDa subunit reveals homology to other ATPases 总被引:18,自引:0,他引:18
The vacuolar membrane of Neurospora crassa contains a H+-translocating ATPase composed of at least three subunits with approximate molecular weights of 70,000, 60,000, and 15,000. Both genomic and cDNA clones encoding the largest subunit, which appears to contain the active site of the enzyme, have been isolated and sequenced. The gene for this subunit, designated vma-1, contains six small introns (60-131 base pairs) and encodes a hydrophilic protein of 607 amino acids, Mr 67,121. Within the sequence is a putative nucleotide-binding region, consistent with the proposal that this subunit contains the site of ATP hydrolysis. This 67-kDa polypeptide shows high homology (62% identical residues overall and 84% in the middle of the protein) to the analogous polypeptide of a higher plant vacuolar ATPase. The hypothesis that the vacuolar ATPase is related to F0F1 ATPases is strongly supported by the finding of considerable homology between the 67-kDa subunit of the Neurospora vacuolar ATPase and both the alpha and beta subunits of F0F1 ATPases. 相似文献
2.
Dose-survival curves of four strains of E. coli-B/r her- try-, Bs-1, B/r CSH, and 15T-were obtained in the presence and in the absence of non-toxic levels of several thiol-binding agents-N-ethylmaleimide (NEM), iodoacetamide (IA), and hydroxymercuribenzoate (HMB). The degree of radiosensitization by these agents was estimated from the increase in slope of the dose-survival curve, under anoxic and aerobic conditions. Chemical sensitization of both radioresistant and radiosensitive strains of bacteria with the thiol-binding enzyme poisons NEM, IA, and HMB has been observed. NEM sensitized only under anoxic conditions, IA sensitized under both anoxic and aerobic conditions, although to a much greater extent aerobically, and HMB sensitized only under aerobic conditions. The formation of long-lived radiolytic products toxic to bacteria is observed in sensitization by IA. When sensitization occurs, the magnitude of the dose-modifying factor is equal to or greater than the oxygen enhancement ratio. Inhibition of an energy-requiring enzymic repair process does not seem to be involved as a primary mechanism of sensitization. Interference by thiol-binding agents with a "rapid repair" process which is different from the usual "enzymic repair," and which operates in radio-sensitive as well as in radioresistant bacteria, is suggested. 相似文献
3.
Postural effect on ventilatory control 总被引:1,自引:0,他引:1
4.
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
5.
Shibu Yooseph Cynthia Andrews-Pfannkoch Aaron Tenney Jeff McQuaid Shannon Williamson Mathangi Thiagarajan Daniel Brami Lisa Zeigler-Allen Jeff Hoffman Johannes B. Goll Douglas Fadrosh John Glass Mark D. Adams Robert Friedman J. Craig Venter 《PloS one》2013,8(12)
Understanding the microbial content of the air has important scientific, health, and economic implications. While studies have primarily characterized the taxonomic content of air samples by sequencing the 16S or 18S ribosomal RNA gene, direct analysis of the genomic content of airborne microorganisms has not been possible due to the extremely low density of biological material in airborne environments. We developed sampling and amplification methods to enable adequate DNA recovery to allow metagenomic profiling of air samples collected from indoor and outdoor environments. Air samples were collected from a large urban building, a medical center, a house, and a pier. Analyses of metagenomic data generated from these samples reveal airborne communities with a high degree of diversity and different genera abundance profiles. The identities of many of the taxonomic groups and protein families also allows for the identification of the likely sources of the sampled airborne bacteria. 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.
8.
Katharine R. Watts Joseline Ratnam Kean-Hooi Ang Karen Tenney Jennifer E. Compton James McKerrow Phillip Crews 《Bioorganic & medicinal chemistry》2010,18(7):2566-2574
Human African trypanosomiasis (HAT, commonly known as African sleeping sickness) is categorized as a neglected disease, as it afflicts >50,000 people annually in sub-saharan Africa, and there are few formal programs in the world focused on drug discovery approaches for this disease. In this study, we examined the crude extracts of two fungal strains (Aspergillus fumigatus and Nectria inventa) isolated from deep water sediment which provided >99% growth inhibition at 1 μg/mL of Trypanosoma brucei, the causative parasite of HAT. A collection of fifteen natural products was supplemented with six semi-synthetic derivatives and one commercially available compound. Twelve of the compounds, each containing a diketopiperazine core, showed excellent activity against T. brucei (IC50 = 0.002–40 μM), with selectivity over mammalian cells as great as 20-fold. The trypanocidal diketopiperazines were also tested against two cysteine protease targets Rhodesain and TbCatB, where five compounds showed inhibition activity at concentrations less than 20 μM. A preliminary activity pattern is described and analyzed. 相似文献
9.
Johnson KG Tenney AP Ghose A Duckworth AM Higashi ME Parfitt K Marcu O Heslip TR Marsh JL Schwarz TL Flanagan JG Van Vactor D 《Neuron》2006,49(4):517-531
The formation and plasticity of synaptic connections rely on regulatory interactions between pre- and postsynaptic cells. We show that the Drosophila heparan sulfate proteoglycans (HSPGs) Syndecan (Sdc) and Dallylike (Dlp) are synaptic proteins necessary to control distinct aspects of synaptic biology. Sdc promotes the growth of presynaptic terminals, whereas Dlp regulates active zone form and function. Both Sdc and Dlp bind at high affinity to the protein tyrosine phosphatase LAR, a conserved receptor that controls both NMJ growth and active zone morphogenesis. These data and double mutant assays showing a requirement of LAR for actions of both HSPGs lead to a model in which presynaptic LAR is under complex control, with Sdc promoting and Dlp inhibiting LAR in order to control synapse morphogenesis and function. 相似文献
10.
Susan DJ Chapple Anna M Crofts S Paul Shadbolt John McCafferty Michael R Dyson 《BMC biotechnology》2006,6(1):49-15