313 research outputs found
Biology, ecology and efficacy of Lecanicillium muscarium as a potential fungal biocontrol of the invasive hemlock woolly adelgid (Adelges tsugae) on eastern hemlock (Tsuga canadensis)
Hemlock woolly adelgid (HWA) is an exotic insect pest of eastern hemlock. The entomopathogen Lecanicillium muscarium, including the commercially available strain MycotalRTM, is a potential candidate for fungal biocontrol. There are many factors to consider when using a fungal biocontrol such as ecology and genetic variation of candidate strains and interactions with other fungi and life stages of the target insect pest. Efforts of this study focused on: 1) sampling for reservoirs for L. muscarium and other Lecanicillium spp., 2) elucidating interactions between Lecanicillium and other fungi present in hemlock tissues and 3) characterizing genetic diversity of Lecanicillium and subsequent entomopathogenicity against HWA. Six Lecanicillium isolates were recovered out of 2,954 total fungal colonies isolated across all substrates, resulting in \u3c1% incidence. Sampling of Mycotal RTM-treated hemlock stands failed to recover any Lecanicillium isolates, which suggests that Lecanicillium does not persist in these environments. To help explain low incidence of Lecanicillium recovery, common fungal community members recovered from these same hemlock tissues were co-plated with Lecanicillium to evaluate inhibitory effects. These frequently recovered fungi included Colletotrichum, Epicoccum, Pestalotiopsis, Rhizosphaera and an undescribed Leotiomycete. The Leotiomycete was shown to have inhibitory effects on several species of Lecanicillium. Since the Leotiomycete fungus is present 17% of the time on average, this could be a significant factor influencing the persistence of Lecanicillium in the environment. To further understand relationships among Lecanicillium, multi-gene phylogenetic analyses were conducted. Six separate phylogenetic analyses, with data partitioned by individual genes produced some complementary results and supported the monophyly of Lecanicillium sensu strictu and close relationships among L. muscarium and L. longisporum as well as uncovered novel linages of Lecanicillium. The phylogenetic trees informed selection of a diverse set of isolates used in entomopathogenicity testing. All isolates used were found to be pathogenic against HWA but virulence among fungal species and isolates varied. Mycotal RTM utilizes a virulent strain for an inundative augmentative approach to bolster naturally low population of Lecanicillium present in hemlock stands. However, its low infection rate on egg masses (33%) could indicate that other Lecanicillium isolates used in this study, especially North American strains, might be a better candidate for widespread application against HWA in the eastern United States
Elucidating disease dynamics in the biocontrol of Ailanthus altissima while confirming the host specificity of the vascular wilt pathogen Verticillium nonalfalfae
Ailanthus altissima is a highly invasive exotic tree species entrenched throughout the United States. Since the discovery of a vascular wilt disease of Ailanthus in 2002, caused by the fungus Verticillium nonalfalfae, many studies are investigating its potential as a biocontrol focusing on efficacy, host specificity and disease transmission. This study addresses: the reproductive potential of Ailanthus; if V. dahliae alters Verticillium wilt progression; if hardiness zones influence the individual contributions of two Verticillium spp.; can a unique habitat affect biocontrol efficacy; and can the fungal proteome of V. nonalfalfae allow us to explain differences in host specificity? Cumulative seed production in individual Ailanthus reached ca. 10 and 52 million seeds over a 40-year and 100-year period, respectively. Forested sites inoculated with both Ailanthus pathogenic species of Verticillium experienced the same mortality rates as sites with just V. nonalfalfae alone. When comparing mortality caused by Verticillium wilt in three hardiness zones, it was found that there was no difference in disease progression. Ailanthus established on previous strip mine sites displayed resistance to the pathogen. Tree ring observations and X-ray fluorescence mineral assays indicated high concentrations of iron which inhibited Verticillium infection. Isolates of Verticillium species and strains from different plant hosts displayed differences in pathogenicity to Ailanthus seedlings and had distinct proteomes from each other when analyzed with MALDI-TOF-MS, indicating Verticillium isolates from different sources respond to their host environment differently
Entanglement properties of optical coherent states under amplitude damping
Through concurrence, we characterize the entanglement properties of optical
coherent-state qubits subject to an amplitude damping channel. We investigate
the distillation capabilities of known error correcting codes and obtain upper
bounds on the entanglement depending on the non-orthogonality of the coherent
states and the channel damping parameter. This work provides a first, full
quantitative analysis of these photon-loss codes which are naturally
reminiscent of the standard qubit codes against Pauli errors.Comment: 7 pages, 6 figures. Revised version with small corrections; main
results remain unaltere
New Roles of Government in the Governance of Business Conduct: Implications for Management and Organizational Research
GNSS remote sensing of the Australian tropopause
Radio occultation (RO) techniques that use signals transmitted by Global Navigation Satellite Systems (GNSS) have emerged over the past decade as an important tool for measuring global changes in tropopause temperature and height, a valuable capacity given the tropopause’s sensitivity to temperature variations. This study uses 45,091 RO data from the CHAMP (CHAllenging Minisatellite Payload, 80 months), GRACE (Gravity Recovery And Climate Experiment, 23 months) and COSMIC (Constellation Observing System for Meteorology, Ionosphere, and Climate, 20 months) satellites to analyse the variability of the tropopause’s height and temperature over Australia. GNSS RO temperature profiles from CHAMP, GRACE, and COSMIC are first validated using radiosonde observations provided by the Bureau of Meteorology (Australia). These are compared to RO soundings from between 2001 and 2007 that occurred within 3 h and 100 km of a radiosonde.The results indicate that RO soundings provide data of a comparable quality to radiosonde observations in the tropopause region, with temperature deviations of less than 0.5 ± 1.5 K. An analysis of tropopause height and temperature anomalies indicates a height increase over Australia as a whole of ca. 4.8 ± 1.3 m between September 2001 and April 2008, with a corresponding temperature decrease of −0.019 ± 0.007 K. A similar pattern of increasing height/decreasing temperature was generally observed when determining the spatial distribution of the tropopause height and temperature rate of change over Australia. Although only a short period has been considered in this study, a function of the operating time of these satellites, the results nonetheless show an increase in the height of the tropopause over Australia during this period and thus may indicate regional warming. Several mechanisms could be responsible for these changes, such as an increase in the concentration of greenhouse gases in the atmosphere, and lower stratospheric cooling due to ozone loss, both of which have been observed during the last decades
Observations and analysis of polar stratospheric clouds detected by POAM III and SAGE III during the SOLVE II/VINTERSOL campaign in the 2002/2003 Northern Hemisphere winter
The Polar Ozone and Aerosol Measurement and Stratospheric Aerosol and Gas Experiment instruments both observed high numbers of polar stratospheric clouds (PSCs) in the polar region during the second SAGE Ozone Loss and Validation (SOLVE II) and Validation of INTERnational Satellites and Study of Ozone Loss (VINTERSOL) campaign, conducted during the 2002/2003 Northern Hemisphere winter. Between 15 November 2002 (14 November 2002) and 18 March 2003 (21 March 2003) SAGE (POAM) observed 122 (151) aerosol extinction profiles containing PSCs. PSCs were observed on an almost daily basis, from early December through 15 January, in both instruments. No PSCs were observed from either instrument from 15 January until 4 February, and from then only sparingly in three periods in mid- and late February and mid-March. In early December, PSCs were observed in the potential temperature range from roughly 375 K to 750 K. Throughout December the top of this range decreases to near 600 K. In February and March, PSC observations were primarily constrained to potential temperatures below 500 K. The PSC observation frequency as a function of ambient temperature relative to the nitric acid-trihydrate saturation point (using a nitric acid profile prior to denitrification) was used to infer irreversible denitrification. By late December 38% denitrification was inferred at both the 400–475 K and 475–550 K potential temperature ranges. By early January extensive levels of denitrification near 80% were inferred at both potential temperature ranges, and the air remained denitrified at least through early March
Remote Predictive Mapping 3. Optical Remote Sensing – A Review for Remote Predictive Geological Mapping in Northern Canada
Optical remotely sensed data have broad application for geological mapping in Canada’s North. Diverse remote sensors and digital image processing techniques have specific mapping functions, as demonstrated by numerous examples and associated interpretations. Moderate resolution optical sensors are useful for discriminating rock types, whereas sensors that offer increased spectral resolution (i.e. hyperspectral sensors) allow the geologist to identify certain rock types (mainly different types of carbonates, Fe-bearing rocks, sulphates and hydroxyl-(clay-) bearing rocks) as opposed to merely discriminating between them. Increased spatial resolution and the ability to visualize the earth’s surface in stereo are now offered by a host of optical sensors. However, the usefulness of optical remote sensing for geological mapping is highly dependent on the geologic, surficial and biophysical environment, and bedrock predictive mapping is most successful in areas not obscured by thick drift and vegetation/lichen cover, which is typical of environments proximal to coasts. In general, predictive mapping of surficial materials has fewer restrictions. Optical imagery can be enhanced in a variety of ways and fused with other geo-science datasets to produce imagery that can be visually interpreted in a GIS environment. Computer processing techniques are useful for undertaking more quantitative analyses of imagery for mapping bedrock, surficial materials and geomorphic or glacial features.
SOMMAIRE
Les données recueillies par télédétection optique offrent beaucoup de possibilités pour la cartographie géologique des régions nordiques canadiennes. La diversité des télécapteurs et des techniques de traitement numérique des données permet la définition de fonctions de cartographie spécifique, tel que l’illustre de nombreux exemples et interprétations associées. Des capteurs optiques de moyenne résolution sont utiles pour différencier les types de roche, alors que les capteurs à plus fines résolutions (les capteurs hyperspectraux, par ex.) permettent au géologue de subdiviser certains types de roches (principalement différents types de carbonates, roches ferrugineuses, roches à sulfates et à hydroxyle (argile). Une meilleure résolution spatiale et la fonction de vision stéréoscopique sont maintenant offertes sur une gamme de capteurs optiques. Cela dit, l’utilité de la télédétection optique pour la cartographie géologique est fortement tributaire des conditions de la géologie de surface et de son environnement biophysique, le potentiel prédictif de la télécartographie étant maximal pour les régions exemptes d’une couverture épaisse de dépôts glaciaires ou d’une couverture végétale/lichen caractéristique typique des environnements longeant les côtes. Divers procédés permettent de rehausser l’imagerie optique et de réaliser des fusions avec d’autres jeux de données géoscientifiques et de produire une imagerie visuellement inter-prétable en environnement de SIG. Les techniques de traitement de données par ordinateur sont utiles pour d’autres types d’analyse quantitative d’imagerie pour la cartographie des matériaux de couverture du socle et pour répertorier des formes glaciaires et géomorphologiques
Glacial isostatic uplift of the European Alps
Following the last glacial maximum (LGM), the demise of continental ice sheets induced crustal rebound in tectonically stable regions of North America and Scandinavia that is still ongoing. Unlike the ice sheets, the Alpine ice cap developed in an orogen where the measured uplift is potentially attributed to tectonic shortening, lithospheric delamination and unloading due to deglaciation and erosion. Here we show that ∼90% of the geodetically measured rock uplift in the Alps can be explained by the Earth's viscoelastic response to LGM deglaciation. We modelled rock uplift by reconstructing the Alpine ice cap, while accounting for postglacial erosion, sediment deposition and spatial variations in lithospheric rigidity. Clusters of excessive uplift in the Rhône Valley and in the Eastern Alps delineate regions potentially affected by mantle processes, crustal heterogeneity and active tectonics. Our study shows that even small LGM ice caps can dominate present-day rock uplift in tectonically active regions
First results from the GPS atmosphere sounding experiment TOR aboard the TerraSAR-X satellite
GPS radio occultation events observed between 24 July and 17 November 2008 by the IGOR occultation receiver aboard the TerraSAR-X satellite are processed and analyzed. The comparison of 15 327 refractivity profiles with collocated ECMWF data yield a mean bias between zero and −0.30 % at altitudes between 5 and 30 km. Standard deviations decrease from about 1.4 % at 5 km to about 0.6 % at 10 km altitude, however, increase significantly in the upper stratosphere. At low latitudes mean biases and standard deviations are larger, in particular in the lower troposphere. The results are consistent with 15 159 refractivity observations collected during the same time period by the BlackJack receiver aboard GRACE-A and processed by GFZ's operational processing system. The main difference between the two occultation instruments is the implementation of open-loop signal tracking in the IGOR (TerraSAR-X) receiver which improves the tropospheric penetration depth in terms of ray height by about 2 km compared to the conventional closed-loop data acquired by BlackJack (GRACE-A)
The F238L point mutation in the cannabinoid type 1 receptor enhances basal endocytosis via lipid rafts
Defining functional domains and amino acid residues in G protein coupled receptors (GPCRs) represents an important way to improve rational drug design for this major class of drug targets. The cannabinoid type 1 (CB1) receptor is one of the most abundant GPCRs in the central nervous system and is involved in many physiological and pathophysiological processes. Interestingly, mutagenesis of phenylalanine 238 to a leucine (CB1F238L) has been already linked to a number of both in vitro and in vivo alterations. While CB1F238L causes significantly reduced presynaptic neurotransmitter release at the cellular level, behaviorally this mutation induces increased risk taking, social play behavior and reward sensitivity in rats. However, the molecular mechanisms underlying these changes are not fully understood. In this study, we tested whether the F238L mutation affects trafficking and axonal/presynaptic polarization of the CB1 receptor in vitro. Steady state or ligand modulated surface expression and lipid raft association was analyzed in HEK293 cells stably expressing either CB1wt or CB1F238L receptor. Axonal/presynaptic polarization of the CB1F238L receptor was assessed in transfected primary hippocampal neurons. We show that in vitro the CB1F238L receptor displays increased association with lipid rafts, which coincides with increased lipid raft mediated constitutive endocytosis, leading to a reduction in steady state surface expression of the CB1F238L receptor. Furthermore, the CB1F238L receptor showed increased axonal polarization in primary hippocampal neurons. These data demonstrate that endocytosis of the CB1 receptor is an important mediator of axonal/presynaptic polarization and that phenylalanine 238 plays a key role in CB1 receptor trafficking and axonal polarization
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