582 research outputs found

    Ecological and morphological differentiation among COI haplotype groups in the plant parasitic nematode species \u3ci\u3eMesocriconema xenoplax\u3c/i\u3e

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    DNA barcoding with the mitochondrial COI gene reveals distinct haplotype subgroups within the monophyletic and parthenogenetic nematode species, Mesocriconema xenoplax. Biological attributes of these haplotype groups (HG) have not been explored. An analysis of M. xenoplax from 40 North American sites representing both native plant communities and agroecosystems was conducted to identify possible subgroup associations with ecological, physiological, or geographic factors. A dataset of 132 M. xenoplax specimens was used to generate sequences of a 712 bp region of the cytochrome oxidase subunit I gene. Maximum-likelihood and Bayesian phylogenies recognized seven COI HG (≄99/0.99 posterior probability/bootstrap value). Species delimitation metrics largely supported the genetic integrity of the HG. Discriminant function analysis of HG morphological traits identified stylet length, total body length, and stylet knob width as the strongest distinguishing features among the seven groups, with stylet length as the strongest single distinguishing morphological feature. Multivariate analysis identified land cover, ecoregion, and maximum temperature as predictors of 53.6% of the total variation (P = 0.001). Within land cover, HG categorized under “herbaceous,” “woody wetlands,” and “deciduous forest” were distinct in DAPC and RDA analyses and were significantly different (analysis of molecular variance P = 0.001). These results provide empirical evidence for molecular, morphological, and ecological differentiation associated with HG within the monophyletic clade that represents the species Mesocriconema xenoplax

    Population structure and phenotypic variation of \u3ci\u3eSclerotinia sclerotiorum\u3c/i\u3e from dry bean (\u3ci\u3ePhaseolus vulgaris\u3c/i\u3e) in the United States

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    The ascomycete pathogen Sclerotinia sclerotiorum is a necrotrophic pathogen on over 400 known host plants, and is the causal agent of white mold on dry bean. Currently, there are no known cultivars of dry bean with complete resistance to white mold. For more than 20 years, bean breeders have been using white mold screening nurseries (wmn) with natural populations of S. sclerotiorum to screen new cultivars for resistance. It is thus important to know if the genetic diversity in populations of S. sclerotiorum within these nurseries (a) reflect the genetic diversity of the populations in the surrounding region and (b) are stable over time. Furthermore, previous studies have investigated the correlation between mycelial compatibility groups (MCG) and multilocus haplotypes (MLH), but none have formally tested these patterns.We genotyped 366 isolates of S. sclerotiorum from producer fields and wmn surveyed over 10 years in 2003–2012 representing 11 states in the United States of America, Australia, France, and Mexico at 11 microsatellite loci resulting in 165 MLHs. Populations were loosely structured over space and time based on analysis of molecular variance and discriminant analysis of principal components, but not by cultivar, aggressiveness, or field source. Of all the regions tested, only Mexico (n = 18) shared no MLHs with any other region. Using a bipartite network-based approach, we found no evidence that the MCGs accurately represent MLHs. Our study suggests that breeders should continue to test dry bean lines in several wmn across the United States to account for both the phenotypic and genotypic variation that exists across regions

    System engineering toolbox for design-oriented engineers

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    This system engineering toolbox is designed to provide tools and methodologies to the design-oriented systems engineer. A tool is defined as a set of procedures to accomplish a specific function. A methodology is defined as a collection of tools, rules, and postulates to accomplish a purpose. For each concept addressed in the toolbox, the following information is provided: (1) description, (2) application, (3) procedures, (4) examples, if practical, (5) advantages, (6) limitations, and (7) bibliography and/or references. The scope of the document includes concept development tools, system safety and reliability tools, design-related analytical tools, graphical data interpretation tools, a brief description of common statistical tools and methodologies, so-called total quality management tools, and trend analysis tools. Both relationship to project phase and primary functional usage of the tools are also delineated. The toolbox also includes a case study for illustrative purposes. Fifty-five tools are delineated in the text

    Pressure Gradient Effects on Hypersonic Cavity Flow Heating

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    The effect of a pressure gradient on the local heating disturbance of rectangular cavities tested at hypersonic freestream conditions has been globally assessed using the two-color phosphor thermography method. These experiments were conducted in the Langley 31-Inch Mach 10 Tunnel and were initiated in support of the Space Shuttle Return-To-Flight Program. Two blunted-nose test surface geometries were developed, including an expansion plate test surface with nearly constant negative pressure gradient and a flat plate surface with nearly zero pressure gradient. The test surface designs and flow characterizations were performed using two-dimensional laminar computational methods, while the experimental boundary layer state conditions were inferred using the measured heating distributions. Three-dimensional computational predictions of the entire model geometry were used as a check on the design process. Both open-flow and closed-flow cavities were tested on each test surface. The cavity design parameters and the test condition matrix were established using the computational predictions. Preliminary conclusions based on an analysis of only the cavity centerline data indicate that the presence of the pressure gradient did not alter the open cavity heating for laminar-entry/laminar-exit flows, but did raise the average floor heating for closed cavities. The results of these risk-reduction studies will be used to formulate a heating assessment of potential damage scenarios occurring during future Space Shuttle flights

    Cavity Heating Experiments Supporting Shuttle Columbia Accident Investigation

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    The two-color thermographic phosphor method has been used to map the local heating augmentation of scaled idealized cavities at conditions simulating the windward surface of the Shuttle Orbiter Columbia during flight STS-107. Two experiments initiated in support of the Columbia Accident Investigation were conducted in the Langley 20-Inch Mach 6 Tunnel. Generally, the first test series evaluated open (length-to-depth less than 10) rectangular cavity geometries proposed as possible damage scenarios resulting from foam and ice impact during launch at several discrete locations on the vehicle windward surface, though some closed (length-to-depth greater than 13) geometries were briefly examined. The second test series was designed to parametrically evaluate heating augmentation in closed rectangular cavities. The tests were conducted under laminar cavity entry conditions over a range of local boundary layer edge-flow parameters typical of re-entry. Cavity design parameters were developed using laminar computational predictions, while the experimental boundary layer state conditions were inferred from the heating measurements. An analysis of the aeroheating caused by cavities allowed exclusion of non-breeching damage from the possible loss scenarios being considered during the investigation

    Characterization of \u3ci\u3eNeofabraea actinidiae\u3c/i\u3e and \u3ci\u3eN. brasiliensis\u3c/i\u3e as causal agents of apple bull’s-eye rot in southern Brazil

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    The causal agents of apple bull’s-eye rot in southern Brazil have recently been described as Neofabraea actinidiae and N. brasiliensis. Isolates of both species were evaluated for response of mycelial growth index (MGI) to different temperatures, enzyme production, mycelial growth inhibition and effective concentrations (EC50 and EC100) of the fungicides triflumizole, pyrimethanil and thiophanate methyl, as well as aggressiveness on fruits of ‘Fuji’ hybrid and ‘Pink Lady’. There was significantly lower mycelium growth in N. brasiliensis compared with N. actinidiae at all temperatures tested. Neither species grew at 3 and 32°C. There were minor differences in production of enzymes in the two species, with all N. brasiliensis isolates showing no production of pectolyase at pH 7. The lowest EC50 and EC100 values were observed with thiophanate methyl. In general, ‘Fuji’ fruits were more susceptible to Neofabraea infection and had larger lesions, while N. brasiliensis isolates showed greater aggressiveness on ‘Fuji’ hybrid and ‘Pink lady’ fruits compared with N. actinidiae. Dans le sud du BrĂ©sil, les agents causaux du chancre gloĂ©sporien de la pomme ont rĂ©cemment Ă©tĂ© dĂ©crits comme Ă©tant Neofabraea actinidiae et N. brasiliensis. Des isolats des deux espĂšces ont Ă©tĂ© Ă©valuĂ©s en fonction de la rĂ©action de l’indice de croissance mycĂ©lienne Ă  diffĂ©rentes tempĂ©ratures, de la production enzymatique, de l’inhibition de la croissance mycĂ©lienne et des concentrations efficaces (CE50 et CE100) des fongicides triflumizole, pyrimĂ©thanil et triophanate mĂ©thyle, ainsi qu’en fonction de leur agressivitĂ© Ă  l’égard de la pomme hybride Fuji et de la Pink Lady. La croissance mycĂ©lienne chez N. brasiliensis Ă©tait considĂ©rablement plus faible que chez N. actinidiae, et ce, Ă  toutes les tempĂ©ratures testĂ©es. Aucune espĂšce ne s’est dĂ©veloppĂ©e Ă  3 ou Ă  32°C. Chez les deux espĂšces, il y a eu de petites diffĂ©rences quant Ă  la production enzymatique, tous les isolats de N. brasiliensis n’affichant aucune production de pectolyase Ă  pH 7. Les plus faibles valeurs de CE50 et de CE100 observĂ©es ont Ă©tĂ© celles du triophanate mĂ©thyle. Dans l’ensemble, les Fuji Ă©taient plus sujettes Ă  l’infection causĂ©e par Neofabraea et affichaient des lĂ©sions plus Ă©tendues, tandis que les isolats de N. brasiliensis Ă©taient plus agressifs Ă  l’égard de l’hybride Fuji et de la Pink Lady que ceux de N. actinidiae

    Characterization of \u3ci\u3eNeofabraea actinidiae\u3c/i\u3e and \u3ci\u3eN. brasiliensis\u3c/i\u3e as causal agents of apple bull’s-eye rot in southern Brazil

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    The causal agents of apple bull’s-eye rot in southern Brazil have recently been described as Neofabraea actinidiae and N. brasiliensis. Isolates of both species were evaluated for response of mycelial growth index (MGI) to different temperatures, enzyme production, mycelial growth inhibition and effective concentrations (EC50 and EC100) of the fungicides triflumizole, pyrimethanil and thiophanate methyl, as well as aggressiveness on fruits of ‘Fuji’ hybrid and ‘Pink Lady’. There was significantly lower mycelium growth in N. brasiliensis compared with N. actinidiae at all temperatures tested. Neither species grew at 3 and 32°C. There were minor differences in production of enzymes in the two species, with all N. brasiliensis isolates showing no production of pectolyase at pH 7. The lowest EC50 and EC100 values were observed with thiophanate methyl. In general, ‘Fuji’ fruits were more susceptible to Neofabraea infection and had larger lesions, while N. brasiliensis isolates showed greater aggressiveness on ‘Fuji’ hybrid and ‘Pink lady’ fruits compared with N. actinidiae. Dans le sud du BrĂ©sil, les agents causaux du chancre gloĂ©sporien de la pomme ont rĂ©cemment Ă©tĂ© dĂ©crits comme Ă©tant Neofabraea actinidiae et N. brasiliensis. Des isolats des deux espĂšces ont Ă©tĂ© Ă©valuĂ©s en fonction de la rĂ©action de l’indice de croissance mycĂ©lienne Ă  diffĂ©rentes tempĂ©ratures, de la production enzymatique, de l’inhibition de la croissance mycĂ©lienne et des concentrations efficaces (CE50 et CE100) des fongicides triflumizole, pyrimĂ©thanil et triophanate mĂ©thyle, ainsi qu’en fonction de leur agressivitĂ© Ă  l’égard de la pomme hybride Fuji et de la Pink Lady. La croissance mycĂ©lienne chez N. brasiliensis Ă©tait considĂ©rablement plus faible que chez N. actinidiae, et ce, Ă  toutes les tempĂ©ratures testĂ©es. Aucune espĂšce ne s’est dĂ©veloppĂ©e Ă  3 ou Ă  32°C. Chez les deux espĂšces, il y a eu de petites diffĂ©rences quant Ă  la production enzymatique, tous les isolats de N. brasiliensis n’affichant aucune production de pectolyase Ă  pH 7. Les plus faibles valeurs de CE50 et de CE100 observĂ©es ont Ă©tĂ© celles du triophanate mĂ©thyle. Dans l’ensemble, les Fuji Ă©taient plus sujettes Ă  l’infection causĂ©e par Neofabraea et affichaient des lĂ©sions plus Ă©tendues, tandis que les isolats de N. brasiliensis Ă©taient plus agressifs Ă  l’égard de l’hybride Fuji et de la Pink Lady que ceux de N. actinidiae

    Characterization of Neofabraea actinidiae and N. brasiliensis as causal agents of apple bull's-eye rot in southern Brazil.

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    The causal agents of apple bull?s-eye rot in southern Brazil have recently been described as Neofabraea actinidiae and N. brasiliensis. Isolates of both species were evaluated for response of mycelial growth index (MGI) to different temperatures, enzyme production, mycelial growth inhibition and effective concentrations (EC 50 and EC 100 ) of the fungicides tri fl umizole, pyrimethanil and thiophanate methyl, as well as aggres- siveness on fruits of "Fuji " hybrid and " Pink Lady " . There was signi ficantly lower mycelium growth in N. brasiliensis compared with N. actinidiae at all temperatures tested. Neither species grew at 3 and 32°C. There were minor differences in production of enzymes in the two species, with all N. brasiliensis isolates showing no production of pectolyase at pH 7. The lowest EC 50 and EC 100 values were observed with thiophanate methyl. In general, " Fuji " fruits were more susceptible to Neofabraea infection and had larger lesions, while N. brasiliensis isolates showed greater aggressiveness on " Fuji " hybrid and " Pink lady " fruits compared with N. actinidiae

    Aero-Heating of Shallow Cavities in Hypersonic Freestream Flow

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    The purpose of these experiments and analysis was to augment the heating database and tools used for assessment of impact-induced shallow-cavity damage to the thermal protection system of the Space Shuttle Orbiter. The effect of length and depth on the local heating disturbance of rectangular cavities tested at hypersonic freestream conditions has been globally assessed using the two-color phosphor thermography method. These rapid-response experiments were conducted in the Langley 31-Inch Mach 10 Tunnel and were initiated immediately prior to the launch of STS-114, the initial flight in the Space Shuttle Return-To-Flight Program, and continued during the first week of the mission. Previously-designed and numerically-characterized blunted-nose baseline flat plates were used as the test surfaces. Three-dimensional computational predictions of the entire model geometry were used as a check on the design process and the two-dimensional flow assumptions used for the data analysis. The experimental boundary layer state conditions were inferred using the measured heating distributions on a no-cavity test article. Two test plates were developed, each containing 4 equally-spaced spanwise-distributed cavities. The first test plate contained cavities with a constant length-to-depth ratio of 8 with design point depth-to-boundary-layer-thickness ratios of 0.1, 0.2, 0.35, and 0.5. The second test plate contained cavities with a constant design point depth-to-boundary-layer-thickness ratio of 0.35 with length-to-depth ratios of 8, 12, 16, and 20. Cavity design parameters and the test condition matrix were established using the computational predictions. Preliminary results indicate that the floor-averaged Bump Factor (local heating rate nondimensionalized by upstream reference) at the tested conditions is approximately 0.3 with a standard deviation of 0.04 for laminar-in/laminar-out conditions when the cavity length-to-boundary-layer thickness is between 2.5 and 10 and for cavities in the depth-to-boundary-layer-thickness range of 0.3 to 0.8. Over this same range of conditions and parameters, preliminary results also indicate that the maximum Bump Factor on the cavity centerline falls between 2.0 and 2.75, as long as the cavity-exit conditions remain laminar. Cavities with length-to-boundary-layer-thickness ratio less than 2.5 can not be easily classified with this approach and require further analysis

    Diverse inflammatory responses in transgenic mouse models of Alzheimer's disease and the effect of immunotherapy on these responses

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    While the presence of an inflammatory response in AD (Alzheimer's disease) is well known, the data on inflammation are conflicting, suggesting that inflammation either attenuates pathology, exacerbates it or has no effect. Our goal was to more fully characterize the inflammatory response in APP (amyloid precursor protein) transgenic mice with and without disease progression. In addition, we have examined how anti-AÎČ (amyloid ÎČ-peptide) immunotherapy alters this inflammatory response. We have used quantitative RT–PCR (reverse transcription–PCR) and protein analysis to measure inflammatory responses ranging from pro-inflammatory to anti-inflammatory and repair factors in transgenic mice that develop amyloid deposits only (APPSw) and amyloid deposits with progression to tau pathology and neuron loss [APPSw/NOS2−/− (nitric oxide synthase 2−/−)]. We also examined tissues from previously published immunotherapy studies. These studies were a passive immunization study in APPSw mice and an active vaccination study in APPSw/NOS2−/− mice. Both studies have already been shown to lower amyloid load and improve cognition. We have found that amyloid deposition is associated with high expression of alternative activation and acquired deactivation genes and low expression of pro-inflammatory genes, whereas disease progression is associated with a mixed phenotype including increased levels of some classical activation factors. Immunotherapy targeting amyloid deposition in both mouse models resulted in decreased alternative inflammatory markers and, in the case of passive immunization, a transient increase in pro-inflammatory markers. Our results suggest that an alternative immune response favours retention of amyloid deposits in the brain, and switching away from this state by immunotherapy permits removal of amyloid
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