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991.
The detection of Aspergillus fumigatus hyphae in bronchoalveolar lavage fluid (BAL) and sputum is diagnostically useful in patients at risk of invasive aspergillosis. We report a dedicated enzymatic-chemical sample pretreatment that allows the application of a previously described solid phase cytometry (SPC) method for detection of A. fumigatus hyphae in sputum and BAL samples. Non-specific detection of fungal hyphae by SPC is based on a 'viability' staining using carboxyfluorescein diacetate. For a specific detection of A. fumigatus hyphae by SPC, viability staining is combined with a pre-incubation at 45 degrees C, immunofluorescent labelling and microscopic recognition of the characteristic hyphal morphology. Low numbers of A. fumigatus hyphae (2-10 hyphae/sample) have now been demonstrated in spiked sputum using the non-specific and specific staining in 2.5 and 8.5 h, respectively. 相似文献
992.
Engelbrektson AL Korzenik JR Sanders ME Clement BG Leyer G Klaenhammer TR Kitts CL 《FEMS microbiology ecology》2006,57(2):239-250
A large number of studies have investigated gastrointestinal microbiota and changes in the gastrointestinal community. However, a concern in these studies is how best to assess changes in gastrointestinal community structure. This paper presents two different human trials where the fecal terminal restriction fragment length polymorphism data sets were analyzed to search for treatment effects. Principle components analysis and cluster analysis based on grouped data are compared with analysis of data by subject using distance coefficients. Comparison with baseline within an individual before grouping by treatment provided a clearer indication of treatment effects than did an evaluation of data grouped before analysis. In addition, a large within-subject sample size and multiple baseline samples are necessary to accurately analyze treatment effects. 相似文献
993.
Reeves WK Loftis AD Sanders F Spinks MD Wills W Denison AM Dasch GA 《Experimental & applied acarology》2006,39(3-4):321-329
Argasid ticks are vectors of viral and bacterial agents of humans and animals. Carios capensis, a tick of seabirds, infests the nests of brown pelicans, Pelecanus occidentalis, and other ground nesting birds along the coast of South Carolina. This tick is associated with pelican nest abandonment and could pose a threat to humans visiting pelican rookeries if visitors are exposed to ticks harboring infectious agents. We collected ticks from a pelican rookery on Deveaux Bank, South Carolina and screened 64 individual ticks, six pools of larvae, and an egg mass for DNA from Bartonella, Borrelia, Coxiella, and Rickettsia by polymerase chain reaction amplification and sequencing. Ticks harbored DNA from “Borrelia lonestari”, a novel Coxiella sp., and three species of Rickettsia, including Rickettsia felis and two undescribed Rickettsia spp. DNA from the Coxiella and two undescribed Rickettsia were detected in unfed larvae that emerged in the laboratory, which implies these agents are transmitted vertically by female ticks. We partially characterize the novel Coxiella by molecular means. 相似文献
994.
Sanders IR 《Trends in ecology & evolution》2006,21(12):656-658
Among different species of eukaryotes, the extent and evolutionary significance of horizontal gene transfer remains poorly understood. A newly published study by Friesen and colleagues indicates that a recent gene transfer between two species of fungi has enabled the recipient to rapidly acquire high virulence on wheat. The study highlights a mechanism by which diseases can suddenly emerge, but also brings up the controversial issues of how horizontal gene transfer occurs and whether fungal incompatibility barriers to gene flow are more 'leaky' than was previously thought. 相似文献
995.
Nucleotide regulation of the voltage-dependent nonselective cation conductance in murine colonic myocytes 总被引:1,自引:0,他引:1
Monaghan KP Koh SD Ro S Yeom J Horowitz B Sanders KM 《American journal of physiology. Cell physiology》2006,291(5):C985-C994
ATP is proposed to be a major inhibitory neurotransmitter in the gastrointestinal (GI) tract, causing hyperpolarization and smooth muscle relaxation. ATP activates small-conductance Ca2+-activated K+ channels that are involved in setting the resting membrane potential and causing inhibitory junction potentials. No reports are available examining the effects of ATP on voltage-dependent inward currents in GI smooth muscle cells. We previously reported two types of voltage-dependent inward currents in murine proximal colonic myocytes: a low-threshold voltage-activated, nonselective cation current (IVNSCC) and a relatively high-threshold voltage-activated (L-type) Ca2+ current (IL). Here we have investigated the effects of ATP on these currents. External application of ATP (1 mM) did not affect IVNSCC or IL in dialyzed cells. ATP (1 mM) increased IVNSCC and decreased IL in the perforated whole-cell configuration. UTP and UDP (1 mM) were more potent than ATP on IVNSCC. ADP decreased IL but had no effect on IVNSCC. The order of effectiveness was UTP = UDP > ATP > ADP. These effects were not blocked by pyridoxal phosphate-6-azo(benzene-2,4-disulfonic acid) (PPADS), but the phospholipase C inhibitor U-73122 reversed the effects of ATP on IVNSCC. ATP stimulation of IVNSCC was also reversed by protein kinase C (PKC) inhibitors chelerythrine chloride or bisindolylmaleimide I. Phorbol 12,13-dibutyrate mimicked the effects of ATP. RT-PCR showed that P2Y4 is expressed by murine colonic myocytes, and this receptor is relatively insensitive to PPADS. Our data suggest that ATP activates IVNSCC and depresses IL via binding of P2Y4 receptors and stimulation of the phospholipase C/PKC pathway. inhibitory junction potentials; smooth muscle; enteric nervous system 相似文献
996.
Role of ATP hydrolysis in the DNA translocase activity of the bovine papillomavirus (BPV-1) E1 helicase 总被引:1,自引:1,他引:0
The E1 protein of bovine papillomavirus type-1 is the viral replication initiator protein and replicative helicase. Here we show that the C-terminal ~300 amino acids of E1, that share homology with members of helicase superfamily 3 (SF3), can act as an autonomous helicase. E1 is monomeric in the absence of ATP but assembles into hexamers in the presence of ATP, single-stranded DNA (ssDNA) or both. A 16 base sequence is the minimum for efficient hexamerization, although the complex protects ~30 bases from nuclease digestion, supporting the notion that the DNA is bound within the protein complex. In the absence of ATP, or in the presence of ADP or the non–hydrolysable ATP analogue AMP–PNP, the interaction with short ssDNA oligonucleotides is exceptionally tight (T1/2 > 6 h). However, in the presence of ATP, the interaction with DNA is destabilized (T1/2 ~60 s). These results suggest that during the ATP hydrolysis cycle an internal DNA-binding site oscillates from a high to a low-affinity state, while protein–protein interactions switch from low to high affinity. This reciprocal change in protein–protein and protein–DNA affinities could be part of a mechanism for tethering the protein to its substrate while unidirectional movement along DNA proceeds. 相似文献
997.
Common determinants in DNA melting and helicase-catalysed DNA unwinding by papillomavirus replication protein E1 总被引:4,自引:2,他引:2
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E1 and T-antigen of the tumour viruses bovine papillomavirus (BPV-1) and Simian virus 40 (SV40) are the initiator proteins that recognize and melt their respective origins of replication in the initial phase of DNA replication. These proteins then assemble into processive hexameric helicases upon the single-stranded DNA that they create. In T-antigen, a characteristic loop and hairpin structure (the pre-sensor 1β hairpin, PS1βH) project into a central cavity generated by protein hexamerization. This channel undergoes large ATP-dependent conformational changes, and the loop/PS1βH is proposed to form a DNA binding site critical for helicase activity. Here, we show that conserved residues in BPV E1 that probably form a similar loop/hairpin structure are required for helicase activity and also origin (ori) DNA melting. We propose that DNA melting requires the cooperation of the E1 helicase domain (E1HD) and the origin binding domain (OBD) tethered to DNA. One possible mechanism is that with the DNA locked in the loop/PS1βH DNA binding site, ATP-dependent conformational changes draw the DNA inwards in a twisting motion to promote unwinding. 相似文献
998.
An oviduct-specific and enhancer-like element resides at about -3000 in the chicken ovalbumin gene 总被引:1,自引:0,他引:1
The chicken ovalbumin (Ov) gene is one of the best models to study tissue-specific gene regulation because it is only expressed in the oviduct. In this paper, a tissue-specific element was characterized by 5'-flanking region deletion in combination with in vivo gene electroporation (EP). Plasmids with varying lengths of truncated Ov 5'-flanking region fused to the Renilla luciferase reporter gene were transfected in vivo into oviduct, muscle, and pancreas. A chicken oviduct-specific and enhancer-like region (designated COSE) was implicated between -3100 and -2800. The COSE showed up-regulation of gene expression in oviduct, but not in muscle or in pancreas. The COSE region was further characterized by gel mobility shift assays using nuclear extracts from oviduct, pancreas and liver. With the region from -2900 to -2851, designated T2, there were two distinct protein-DNA complexes: one found only in oviduct extract and the other detected only in pancreas and liver. These data suggest a model where the regulation of Ov gene expression in the oviduct and non-oviduct tissues is exerted at least in part by the presence of protein modulators that bind to the COSE element. 相似文献
999.
Genetic variability in a population of arbuscular mycorrhizal fungi causes variation in plant growth 总被引:5,自引:1,他引:4
Different species of arbuscular mycorrhizal fungi (AMF) alter plant growth and affect plant coexistence and diversity. Effects of within-AMF species or within-population variation on plant growth have received less attention. High genetic variation exists within AMF populations. However, it is unknown whether genetic variation contributes to differences in plant growth. In our study, a population of AMF was cultivated under identical conditions for several generations prior to the experiments thus avoiding environmental maternal effects. We show that genetically different Glomus intraradices isolates from one AMF population significantly alter plant growth in an axenic system and in greenhouse experiments. Isolates increased or reduced plant growth meaning that plants potentially receive benefits or are subject to costs by forming associations with different individuals in the AMF population. This shows that genetic variability in AMF populations could affect host-plant fitness and should be considered in future research to understand these important soil organisms. 相似文献
1000.
The genome of Rhizobium leguminosarum has recognizable core and accessory components 总被引:3,自引:0,他引:3
Young JP Crossman LC Johnston AW Thomson NR Ghazoui ZF Hull KH Wexler M Curson AR Todd JD Poole PS Mauchline TH East AK Quail MA Churcher C Arrowsmith C Cherevach I Chillingworth T Clarke K Cronin A Davis P Fraser A Hance Z Hauser H Jagels K Moule S Mungall K Norbertczak H Rabbinowitsch E Sanders M Simmonds M Whitehead S Parkhill J 《Genome biology》2006,7(4):R34-20