Mechanism of gallic acid biosynthesis in bacteria (Escherichia coli) and walnut (Juglans regia)

Gallic acid (GA), a key intermediate in the synthesis of plant hydrolysable tannins, is also a primary anti-inflammatory, cardio-protective agent found in wine, tea, and cocoa. In this publication, we reveal the identity of a gene and encoded protein essential for GA synthesis. Although it has long been recognized that plants, bacteria, and fungi synthesize and accumulate GA, the pathway leading to its synthesis was largely unknown. Here we provide evidence that shikimate dehydrogenase (SDH), a shikimate pathway enzyme essential for aromatic amino acid synthesis, is also required for GA production. Escherichia coli (E. coli) aroE mutants lacking a functional SDH can be complemented with the plant enzyme such that they grew on media lacking aromatic amino acids and produced GA in vitro. Transgenic Nicotianatabacum lines expressing a Juglans regia SDH exhibited a 500% increase in GA accumulation. The J. regia and E. coli SDH was purified via overexpression in E. coli and used to measure substrate and cofactor kinetics, following reduction of NADP+ to NADPH. Reversed-phase liquid chromatography coupled to electrospray mass spectrometry (RP-LC/ESI–MS) was used to quantify and validate GA production through dehydrogenation of 3-dehydroshikimate (3-DHS) by purified E. coli and J. regia SDH when shikimic acid (SA) or 3-DHS were used as substrates and NADP+ as cofactor. Finally, we show that purified E. coli and J. regia SDH produced GA in vitro

Surface Wettability Drives the Crystalline Surface Assembly of Monodisperse Spheres in Evaporative Colloidal Lithography

The wettability nature of substrates has been found to profoundly influence the surface assembly of monodisperse spherical particles for colloidal suspensions that are dried by evaporation to spontaneously form either periodic or disordered packing arrangements. The self-assembly of spheres has consequences when preparing surface masks for evaporative colloidal lithography. When a droplet of an aqueous suspension of monodisperse latex particles was dried by evaporation on flat substrates that are hydrophilic, a close-packed arrangement was formed spontaneously. However, when a similar aqueous suspension was deposited and dried on relatively hydrophobic substrates such as silicon and glass, a disordered arrangement was produced, revealing that there were negligible regions of hexagonal packing. The wettability of silicon wafers can be rendered to be hydrophilic by certain surface treatments. For example, after ozone exposure, silicon surfaces became hydrophilic as evidenced by changes measured for water contact angles. For silicon surfaces that were exposed to UV/ozone, crystalline arrangements of monodisperse latex spheres were generated with relatively few defects. Such physical or chemical treatments which tailor the wettability of surfaces can be used to improve reproducibility and to lower the density of defects when preparing surface masks for emerging manufacturing processes based on colloidal lithography

A Step Towards A Computing Grid For The LHC Experiments: ATLAS Data Challenge 1

The ATLAS Collaboration at CERN is preparing for the data taking and analysis at the LHC that will start in 2007. Therefore, a series of Data Challenges was started in 2002 whose goals are the validation of the Computing Model, of the complete software suite, of the data model, and to ensure the correctness of the technical choices to be made for the final offline computing environment. A major feature of the first Data Challenge (DC1) was the preparation and the deployment of the software required for the production of large event samples as a worldwide distributed activity. It should be noted that it was not an option to "run the complete production at CERN" even if we had wanted to; the resources were not available at CERN to carry out the production on a reasonable time-scale. The great challenge of organising and carrying out this large-scale production at a significant number of sites around the world had therefore to be faced. However, the benefits of this are manifold: apart from realising the required computing resources, this exercise created worldwide momentum for ATLAS computing as a whole. This report describes in detail the main steps carried out in DC1 and what has been learned form them as a step towards a computing Grid for the LHC experiments