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41.
This study evaluated five commercial extraction kits for their ability to recover DNA from Bacillus anthracis spores and spiked environmental samples. The kits evaluated represent the major types of methodologies which are commercially available for DNA or total nucleic acid extraction, and included the ChargeSwitch gDNA Mini Bacteria Kit, NucliSens Isolation Kit, Puregene Genomic DNA Purification Kit, QIAamp DNA Blood Mini Kit, and the UltraClean Microbial DNA Isolation Kit. Extraction methods were performed using the spores of eight virulent strains of B. anthracis. Viability testing of nucleic acid extracts showed that the UltraClean kit was the most efficient at depleting samples of live B. anthracis spores. TaqMan real-time PCR analysis revealed that the NucliSens, QIAamp and UltraClean kits yielded the best level of detection from spore suspensions. Comparisons of processed samples from spiked swabs and three powder types indicated that DNA extraction using the UltraClean kit resulted in the most consistently positive results and the lowest limit of detection. This study demonstrated that different nucleic extraction methodologies, represented here by various commercial extraction kits, differ in their ability to inactivate live B. anthracis spores as well as DNA yield and purity. In addition, the extraction method used can influence the sensitivity of real-time PCR assays for B. anthracis. 相似文献
42.
We compared habitat characteristics between territories of paired and unpaired males of the long-distance migratory Common Redstart Phoenicurus phoenicurus. Nesting possibilities and reachable sparse vegetation were more abundant in territories of paired males, clearly highlighting the importance of both parameters when implementing habitat enhancements for the species. 相似文献
43.
Bastien Christ Iris Süssenbacher Simone Moser Nicole Bichsel Aurelie Egert Thomas Müller Bernhard Kr?utler Stefan H?rtensteiner 《The Plant cell》2013,25(5):1868-1880
Nonfluorescent chlorophyll catabolites (NCCs) were described as products of chlorophyll breakdown in Arabidopsis thaliana. NCCs are formyloxobilin-type catabolites derived from chlorophyll by oxygenolytic opening of the chlorin macrocycle. These linear tetrapyrroles are generated from their fluorescent chlorophyll catabolite (FCC) precursors by a nonenzymatic isomerization inside the vacuole of senescing cells. Here, we identified a group of distinct dioxobilin-type chlorophyll catabolites (DCCs) as the major breakdown products in wild-type Arabidopsis, representing more than 90% of the chlorophyll of green leaves. The molecular constitution of the most abundant nonfluorescent DCC (NDCC), At-NDCC-1, was determined. We further identified cytochrome P450 monooxygenase CYP89A9 as being responsible for NDCC accumulation in wild-type Arabidopsis; cyp89a9 mutants that are deficient in CYP89A9 function were devoid of NDCCs but accumulated proportionally higher amounts of NCCs. CYP89A9 localized outside the chloroplasts, implying that FCCs occurring in the cytosol might be its natural substrate. Using recombinant CYP89A9, we confirm FCC specificity and show that fluorescent DCCs are the products of the CYP89A9 reaction. Fluorescent DCCs, formed by this enzyme, isomerize to the respective NDCCs in weakly acidic medium, as found in vacuoles. We conclude that CYP89A9 is involved in the formation of dioxobilin-type catabolites of chlorophyll in Arabidopsis. 相似文献
44.
Feedback from community interactions involving mutualisms are a rarely explored mechanism for generating complex population
dynamics. We examined the effects of two linked mutualisms on the population dynamics of a beetle that exhibits outbreak dynamics.
One mutualism involves an obligate association between the bark beetle, Dendroctonus frontalis and two mycangial fungi. The second mutualism involves Tarsonemus mites that are phoretic on D. frontalis (“commensal”), and a blue-staining fungus, Ophiostoma minus. The presence of O. minus reduces beetle larval survival (“antagonistic”) by outcompeting beetle-mutualistic fungi within trees yet supports mite populations
by acting as a nutritional mutualist. These linked interactions potentially create an interaction system with the form of
an endogenous negative feedback loop. We address four hypotheses: (1) Direct negative feedback: Beetles directly increase
the abundance of O. minus, which reduces per capita reproduction of beetles. (2) Indirect negative feedback: Beetles indirectly increase mite abundance,
which increases O. minus, which decreases beetle reproduction. (3) The effect of O. minus on beetles depends on mites, but mite abundance is independent of beetle abundance. (4) The effect of O. minus on beetles is independent of beetle and mite abundance. High Tarsonemus and O. minus abundances were strongly correlated with the decline and eventual local extinction of beetle populations. Manipulation experiments
revealed strong negative effects of O. minus on beetles, but falsified the hypothesis that horizontal transmission of O. minus generates negative feedback. Surveys of beetle populations revealed that reproductive rates of Tarsonemus, O. minus, and beetles covaried in a manner consistent with strong indirect interactions between organisms. Co-occurrence of mutualisms
embedded within a community may have stabilizing effects if both mutualisms limit each other. However, delays and/or non-linearities
in the interaction systems may result in large population fluctuations.
Electronic Supplementary Material Supplementary material is available for this article at and is accessible for authorized users. 相似文献
45.
Path integration and the neural basis of the 'cognitive map' 总被引:1,自引:0,他引:1
McNaughton BL Battaglia FP Jensen O Moser EI Moser MB 《Nature reviews. Neuroscience》2006,7(8):663-678
The hippocampal formation can encode relative spatial location, without reference to external cues, by the integration of linear and angular self-motion (path integration). Theoretical studies, in conjunction with recent empirical discoveries, suggest that the medial entorhinal cortex (MEC) might perform some of the essential underlying computations by means of a unique, periodic synaptic matrix that could be self-organized in early development through a simple, symmetry-breaking operation. The scale at which space is represented increases systematically along the dorsoventral axis in both the hippocampus and the MEC, apparently because of systematic variation in the gain of a movement-speed signal. Convergence of spatially periodic input at multiple scales, from so-called grid cells in the entorhinal cortex, might result in non-periodic spatial firing patterns (place fields) in the hippocampus. 相似文献
46.
The molecular basis for Duchenne versus Becker muscular dystrophy: Correlation of severity with type of deletion 总被引:59,自引:23,他引:59 下载免费PDF全文
M. Koenig A. H. Beggs M. Moyer S. Scherpf K. Heindrich T. Bettecken G. Meng C. R. Müller M. Lindl?f H. Kaariainen A. de la Chapelle A. Kiuru M.-L. Savontaus H. Gilgenkrantz D. Récan J. Chelly J.-C. Kaplan A. E. Covone N. Archidiacono G. Romeo S. Liechti-Gallati V. Schneider S. Braga H. Moser B. T. Darras P. Murphy U. Francke J. D. Chen G. Morgan M. Denton C. R. Greenberg K. Wrogemann L. A. J. Blonden H. M. B. van Paassen G. J. B. van Ommen L. M. Kunkel 《American journal of human genetics》1989,45(4):498-506
About 60% of both Duchenne muscular dystrophy (DMD) and Becker muscular dystrophy (BMD) is due to deletions of the dystrophin gene. For cases with a deletion mutation, the "reading frame" hypothesis predicts that BMD patients produce a semifunctional, internally deleted dystrophin protein, whereas DMD patients produce a severely truncated protein that would be unstable. To test the validity of this theory, we analyzed 258 independent deletions at the DMD/BMD locus. The correlation between phenotype and type of deletion mutation is in agreement with the "reading frame" theory in 92% of cases and is of diagnostic and prognostic significance. The distribution and frequency of deletions spanning the entire locus suggests that many "in-frame" deletions of the dystrophin gene are not detected because the individuals bearing them are either asymptomatic or exhibit non-DMD/non-BMD clinical features. 相似文献
47.
Entorhinal grid cells have periodic, hexagonally patterned firing locations that scale up progressively along the dorsal-ventral axis of medial entorhinal cortex. This topographic expansion corresponds with parallel changes in cellular properties dependent on the hyperpolarization-activated cation current (Ih), which is conducted by hyperpolarization-activated cyclic nucleotide-gated (HCN) channels. To test the hypothesis that grid scale is determined by Ih, we recorded grid cells in mice with forebrain-specific knockout of HCN1. We find that, although the dorsal-ventral gradient of the grid pattern was preserved in HCN1 knockout mice, the size and spacing of the grid fields, as well as the period of the accompanying theta modulation, was expanded at all dorsal-ventral levels. There was no change in theta modulation of simultaneously recorded entorhinal interneurons. These observations raise the possibility that, during self-motion-based navigation, Ih contributes to the gain of the transformation from movement signals to spatial firing fields. 相似文献
48.
Yue T Partyka K Maupin KA Hurley M Andrews P Kaul K Moser AJ Zeh H Brand RE Haab BB 《Proteomics》2011,11(18):3665-3674
The current best serum marker for pancreatic cancer, CA 19-9, detects a carbohydrate antigen on multiple protein carriers. Better knowledge of the protein carriers of the CA 19-9 antigen in various disease states may lead to improved diagnostic tests. To identify proteins that carry the CA 19-9 antigen, we immunoprecipitated the CA 19-9 antigen from pooled sera and identified the associated proteins using MS. Among the high-confidence identifications, we confirmed the presence of the CA 19-9 antigen on Apolipoprotein B-100 by antibody arrays and Western blot and on kininogen, ARVCF, and Apolipoprotein E by antibody arrays. We characterized the frequency and levels of the CA 19-9 antigen on the four proteins across various patient groups (pancreatic cancer, pancreatitis, and healthy controls) using antibody arrays. Nearly, 10-25% of the subjects showed elevations of the antigen on each protein, but the elevations were not associated with disease state or total CA 19-9 levels. These results contribute to our knowledge of the carrier proteins of an important functional glycan and the rate at which the glycan is displayed. This work also demonstrates a strategy for using the complementary methods of MS and antibody microarrays to identify protein carriers of glycans and assess the diagnostic value of measuring glycans on individual proteins. 相似文献
49.
The presynaptic dopamine (DA) D2 receptor-mediated regulation of ATP-sensitive potassium (K+
ATP) channels was examined in slices of the rat caudate-putamen. When slices were incubated with the specific D2 receptor antagonist (–)-sulpiride (SLP), a concentration-dependent increase of extracellular DA release was observed. SLP-induced enhancement was completely antagonized by coincubation with the K+
ATP channel opener diazoxide (DIA). Treatment of slices with the D2 receptor agonist quinpirole (QUI) almost completely inhibited DA outflow induced by the K+
ATP channel blocker butanedione-monoxime (BDM). Coincubation of SLP and guanosine triphosphate (GTP) or its non-hydrolizable analogue guanylyl-5-imidodiphosphate [Gpp(NH)p], significantly reduced the SLP-induced effect on DA levels. Furthermore, we observed that BDM-induced DA outflow was markedly inhibited by G protein activators suggesting an additional receptor-independent regulation of K+
ATP channel gating. Our results suggest that PTX-sensitive G proteins are involved in the signal transduction between D2 receptors and K+
ATP channels. Furthermore, K+
ATP channels can be modulated in a receptor-independent mechanism by G protein activators. 相似文献
50.
Niche breadth explains the range size of European-centred butterflies,but dispersal ability does not
Johannes Hausharter Sonia Rashid Johannes Wessely Patrick Strutzenberger Dietmar Moser Andreas Gattringer Konrad Fiedler Karl Hülber Stefan Dullinger 《Global Ecology and Biogeography》2023,32(9):1535-1548