196,054 research outputs found
SNF1 protein kinase is important for growth and full virulence of Botrytis cinerea.
No full textAt early stages of infection, Botrytis cinerea secretes a wide spectrum of plant cell wall degrading enzymes (CWDEs) to facilitate penetration into host. So far, only the polygalacturonases PG1 and PG2 and the xylanase XYN11A were proved by reverse genetics to be required for virulence. Verification of the function of single members of the different CWDE classes is indeed difficult, due to gene redundancy in multigenic families.
In various plant pathogenic fungi, production of these enzymes is under catabolic repression and positively regulated by the snf1 (sucrose non-fermenting 1) gene which is expressed when glucose is depleted.
To examine the function of the snf1 gene in B. cinerea, knock-out mutants were obtained by targeted mutagenesis. The growth of the Δsnf1 mutants was compared with the wild type strain on minimal medium enriched with different simple and complex carbon sources (fructose, sucrose, glucose, xylan, xylose, pectin, polygalacturonic acid, cellulose). A significant reduction of growth was observed on some carbon sources except with glucose and xylan. Microscopic studies verified, that the sporulation of the mutants was almost abolished and unusually shaped mycelia were found. Pathogenicity tests performed on apple fruits displayed a strong defect in colonization by the Δsnf1 mutants with a 60% decrease in virulence.
Pathogenicity tests on plant systems are in progress together with the characterization of possible effects on secretion and expression of CWDEs
Effect of structurally related essential oil components on growth of Botrytis cinerea.
No full textEssential oils are used as an alternative to chemical fungicides mostly to control post-harvest diseases, included grape grey mould. Main components of some essential oils are structurally related but may differ in fungicide activity. The major aim of this work was to compare the fungicidal activity against Botrytis cinerea Pers. of some related components of essential oils.
The compounds, compared by a plate growth assay, showed the following order of decreasing activity: eugenol, thymol, cinnamaldehyde, isoeugenol, carvacrol, vanillin and guaiacol. The EC50 for eugenol was about 100 μg/ml for the strain B05.10 but was even less against the PM10 strain.
Treatment with eugenol affected also conidia germination, in particular a MIC of 500 μg/ml completely inhibited spore germination of the PM10 strain also at 60 hpi.
The same eugenol concentration was used in a leaf assay and was effective in preventing the infection of both strains of B. cinerea for the entire duration of experiment (10 days). Treatment of grape berries was also performed and confirmed the effectiveness of eugenol in delaying B. cinerea infection. However, the effect was influenced by the grapevine cv; in fact, treated cv. Cabernet Sauvignon was more sensitive to B. cinerea infection than cv. Merlot, although both cvs were similarly infected in the untreated controls.
Although eugenol is known to be an antioxidant compound and increases bacterial membrane permeabilization, and it is reported as a strong inhibitor of soybean lipoxygenase activity, the mechanism by which it affects B. cinerea spore germination and growth is not yet known.
In order to better understand the targets of eugenol and the fungal response to this phenolic compound, transcriptomic analysis of B. cinerea mycelium grown for 72 h and then treated for 6 and 12 hours with eugenol by using EC50 and EC80 concentrations is currently under investigation
Dr. Duane M. Jackson, Morehouse College, July 2011
No full textThis video is a conversation with Dr. Duane M. Jackson. Dr. Jackson talks about his paper, "Recall and the Serial Position Effect: The Role of Primacy and Recency on Accounting Students' Performance." Jackie Daniel, AUC Woodruff Library, is the interviewer
"Reflections on the subject of Emigration from Europe with a view to Settlement in the United States" By M. Carey.
No full text"Reflections on the subject of Emigration from Europe with a view to Settlement in the United States: containing bried sketches of the moral and political character of those states.
By M. Carey, member of the American philosophical, and of the American Antiquarian Society, and author of The Olive Branch, Cindiciae Hibernicae, essays on banking, on political economy, and on internal improvement.
To which are now added the English editor's comments on the subject; together with Important Advice to Emigrants, and Cautions Against Impositions Practiced in the Outports
Dispelling the Myths Behind First-author Citation Counts
No full textWe conducted a full-scale evaluative citation analysis study of scholars in the XML research field to explore just how different from each other author rankings resulting from different citation counting methods actually are, and to demonstrate the capability of emerging data and tools on the Web in supporting more realistic citation counting methods. Our results contest some common arguments for the continued
use of first-author citation counts in the evaluation of scholars, such as high correlations between author rankings by first-author citation counts and other citation
counting methods, and high costs of using more realistic citation counting methods that are not well-supported by the ISI databases. It is argued that increasingly available digital full text research papers make it possible for citation analysis studies to go beyond what the ISI databases have directly supported and to employ more
sophisticated methods
Snf1 Kinase Differentially Regulates Botrytis cinerea Pathogenicity according to the Plant Host
No full textThe Snf1 kinase of the glucose signaling pathway controls the response to nutritional and environmental stresses. In phytopathogenic fungi, Snf1 acts as a global activator of plant cell wall degrading enzymes that are major virulence factors for plant colonization. To characterize its role in the virulence of the necrotrophic fungus Botrytis cinerea, two independent deletion mutants of the Bcsnf1 gene were obtained and analyzed. Virulence of the Δsnf1 mutants was reduced by 59% on a host with acidic pH (apple fruit) and up to 89% on hosts with neutral pH (cucumber cotyledon and French bean leaf). In vitro, Δsnf1 mutants grew slower than the wild type strain at both pH 5 and 7, with a reduction of 20–80% in simple sugars, polysaccharides, and lipidic carbon sources, and these defects were amplified at pH 7. A two-fold reduction in secretion of xylanase activities was observed consequently to the Bcsnf1 gene deletion. Moreover, Δsnf1 mutants were altered in their ability to control ambient pH. Finally, Δsnf1 mutants were impaired in asexual sporulation and did not produce macroconidia. These results confirm the importance of BcSnf1 in pathogenicity, nutrition, and conidiation, and suggest a role in pH regulation for this global regulator in filamentous fungi
Dr. Glendon Swarthout
No full textHosted by Roger M. Busfield, MSU Assistant Professor of Speech and Theater, Meet the Author is designed to introduce a general audience to a contemporary author and their work through in-depth interviews. This episode features a conversation between Dr. Glendon Swarthout, prolific author and English professor at MSU, and assistant professors Sam S. Baskett and Theodore B. Strandness
Simulation of thermal plant optimization and hydraulic aspects of thermal distribution loops for large campuses
No full textFollowing an introduction, the author describes Texas A&M University and its utilities system. After that, the author presents how to construct simulation models for chilled water and heating hot water distribution systems. The simulation model was used in a $2.3 million Ross Street chilled water pipe replacement project at Texas A&M University. A second project conducted at the University of Texas at San Antonio was used as an example to demonstrate how to identify and design an optimal distribution system by using a simulation model. The author found that the minor losses of these closed loop thermal distribution systems are significantly higher than potable water distribution systems. In the second part of the report, the author presents the latest development of software called the Plant Optimization Program, which can simulate cogeneration plant operation, estimate its operation cost and provide optimized operation suggestions. The author also developed detailed simulation models for a gas turbine and heat recovery steam generator and identified significant potential savings. Finally, the author also used a steam turbine as an example to present a multi-regression method on constructing simulation models by using basic statistics and optimization algorithms. This report presents a survey of the author??s working experience at the Energy Systems Laboratory (ESL) at Texas A&M University during the period of January 2002 through March 2004. The purpose of the above work was to allow the author to become familiar with the practice of engineering. The result is that the author knows how to complete a project from start to finish and understands how both technical and nontechnical aspects of a project need to be considered in order to ensure a quality deliverable and bring a project to successful completion. This report concludes that the objectives of the internship were successfully accomplished and that the requirements for the degree of Degree of Engineering have been satisfied
Intern experience at CH���M Hill, Inc.: an internship report
No full textIncludes author's vita"Submitted to the College of Engineering of Texas A&M University in partial
fulfillment of the requirement for the degree of Doctor of Engineering."Includes bibliographical referencesA review of the author's internship experience with CH���M HILL, Inc.
during the period September 1975 through May 1976 is presented. During this nine month
internship the author worked as an Engineer II in the Industrial Processes discipline of this
large consulting engineering firm... The author's prime responsibility was as one of three
lead design engineers on the design of a large wastewater treatment facility for a pulp mill
in Hoquiam, Washington owned by ITT Rayonier Inc. The work generally consisted of the design
of individual treatment units and associated piping and pumping. The purpose of the project
was to provide wastewater treatment capabilities that would satisfy the effluent limitations
(standards) imposed upon the mill by the State of Washington Department of Ecology and the
U.S. Environmental Protection Agency. The author's assignment also entailed necessary
interaction with the project manager and other CH���M HILL design engineers and support staff
members, the client's representatives, and representatives of two other consulting engineering
firms working on the project. Thus, the internship position at CH���M HILL provided considerable
experience coordinating the author's work with the work of other engineers, guiding the design
and administrative efforts of a support staff, and interacting regularly with the client and
other consulting firms. This broad exposure to a variety of engineering and organizational
problems provided a valuable educational experience
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