958 resultados para compound libraries


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The potent antimicrobial compound 2,4-diacetylphloroglucinol (DAPG) is a major determinant of biocontrol activity of plant-beneficial Pseudomonas fluorescens CHA0 against root diseases caused by fungal pathogens. The DAPG biosynthetic locus harbors the phlG gene, the function of which has not been elucidated thus far. The phlG gene is located upstream of the phlACBD biosynthetic operon, between the phlF and phlH genes which encode pathway-specific regulators. In this study, we assigned a function to PhlG as a hydrolase specifically degrades DAPG to equimolar amounts of mildly toxic monoacetylphloroglucinol (MAPG) and acetate. DAPG added to cultures of a DAPG-negative DeltaphlA mutant of strain CHA0 was completely degraded, and MAPG was temporarily accumulated. In contrast, DAPG was not degraded in cultures of a DeltaphlA DeltaphlG double mutant. To confirm the enzymatic nature of PhlG in vitro, the protein was histidine tagged, overexpressed in Escherichia coli, and purified by affinity chromatography. Purified PhlG had a molecular mass of about 40 kDa and catalyzed the degradation of DAPG to MAPG. The enzyme had a kcat of 33 s(-1) and a Km of 140 microM at 30 degrees C and pH 7. The PhlG enzyme did not degrade other compounds with structures similar to DAPG, such as MAPG and triacetylphloroglucinol, suggesting strict substrate specificity. Interestingly, PhlG activity was strongly reduced by pyoluteorin, a further antifungal compound produced by the bacterium. Expression of phlG was not influenced by the substrate DAPG or the degradation product MAPG but was subject to positive control by the GacS/GacA two-component system and to negative control by the pathway-specific regulators PhlF and PhlH.

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We characterize the value function of maximizing the total discounted utility of dividend payments for a compound Poisson insurance risk model when strictly positive transaction costs are included, leading to an impulse control problem. We illustrate that well known simple strategies can be optimal in the case of exponential claim amounts. Finally we develop a numerical procedure to deal with general claim amount distributions.

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This report illustrates the critical role of Enrich Iowa funding in enhancing lifelong learning for Iowans through libraries; improving library resources aimed at assisting job seekers; maintaining library hours that meet library customers’ needs; improving library technology services; and providing safe, accessible library buildings.

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This report illustrates the critical role of Enrich Iowa funding in enhancing lifelong learning for Iowans through libraries; improving library resources aimed at assisting job seekers; maintaining library hours that meet library customers’ needs; improving library technology services; and providing safe, accessible library buildings.

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Iowa is a state rich in libraries, with 543 public libraries; more than 80 college and university libraries; and about 1,000 school libraries. Libraries enrich Iowa and support lifelong learning. The State Library of Iowa actively champions libraries and improves library services for Iowans through its management of the Enrich Iowa program. In accordance with 2006 IOWA ACTS, Chapter 1180 (16)(6), the State Library of Iowa is pleased to submit this report on the impact of state funding on Iowans and Iowa libraries through the Enrich Iowa Program.

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This guide is designed as a finding aid for researchers seeking materials on a particular topic and it indicates the nature and extent of resources for the study of United States history available at the Historical Society of Iowa, the Herbert Hoover Presidential Library and the Iowa University Libraries.

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Postprint (published version)

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The state appropriates funds to support library services to Iowans through the State Library, the Library Service Areas, and state aid to local libraries known as Enrich Iowa. As a result of legislation enacted in 2010, the Iowa Library Association, or ILA, convened a committee to make recommendations regarding reorganization of state-funded library operations and services. The committee's recommendations have been approved by the ILA and endorsed by the State Commission of Libraries. The recommendations described involve the reorganization of the State Library and Library Service Areas.

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This report illustrates the critical role of Enrich Iowa funding in enhancing lifelong learning for Iowans through libraries; improving library resources aimed at assisting job seekers; maintaining library hours that meet library customers’ needs; improving library technology services; and providing safe, accessible library buildings.