Heterologe Expression und Charakterisierung pflanzlicher Transportproteine

Der EST-Klon 121I21T7 aus Arabidopsis thaliana kodiert für einen Xylulose-5-phosphat/Phosphat-Translokator (AtXPT), der einer neuen, vierten Unterfamilie plastidärer Phosphattranslokatoren (pPT) angehört. Unter physiologischen Bedingungen kommen anorganisches Phosphat, Triosephosphate und Xylulose-5-phosphat (Xu5P) als Substrate in Frage, nicht jedoch Hexosephosphate. Datenbankanalysen bezüglich der subzellulären Verteilung von Enzymen des oxidativen Pentosephosphatwegs (OPPP) in Arabidopsis zeigten, dass dieser im Cytosol bis zur Stufe von Xu5P ablaufen kann, während in Plastiden ein vollständiger OPPP operiert. Der XPT könnte eine Rolle in der Kooperation zwischen beiden OPPPs übernehmen, indem er das Endprodukt des cytosolischen OPPP in die Plastiden transportiert. Dieser Funktion wurde eine potentiell große Bedeutung unter Bedingungen eines erhöhten Bedarfs an Erythrose-4-Phosphat für den Shikimatweg beigemessen. Die Analyse der knock-out-Mutante des Translokators (xpt-1) konnte jedoch gerade den letzten Punkt widerlegen. Offensichtlich ist der Shikimatweg quantitativ und qualitativ nicht durch den Ausfall des XPT limitiert. Die Überprüfung diverser physiologischer Parameter legte den Schluss nahe, dass es durch die Mutation zu einer messbaren Veränderung im Zuckerstoffwechsel kommt, die auf noch ungeklärte Weise allgemeine Stresssymptome hervorruft. Insgesamt ist in xpt-1 jedoch keine wesentliche Einschränkung der pflanzlichen Funktionen festzustellen. In der induzierbaren Crassulaceen-Säurestoffwechsel-Pflanze Mesembryanthemum crystallinum wurden durch Transportversuche im rekonstituierten System die Transportaktivitäten dreier pPT-Proteine untersucht. In Übereinstimmung mit physiologischen und molekularbiologischen Untersuchungen anderer Arbeitsgruppen konnten dadurch die CAM-spezifischen Funktionen dieser Translokatoren aufgedeckt werden

Elizabeth Webber Correspondence

Entries include brief biographical information, a handwritten postcard sent in 1940 with Webber\u27s date and place of birth, a letter typed to Miss Margaret Fallin Eicks, whose cookbook review had been noticed by the Maine State Library, requesting information concerning Webber, a letter typed on Boston Evening Transcript, Editorial Rooms, stationery from woman\u27s page editor Eicks, providing Webber\u27s Cambridge, Massachusetts, street address, a typed introductory letter from the Maine State Library to Webber about the Maine Author Collection, a typed letter of reply from Webber on Dinner Is Served ---- Your Room is Ready, A Pocket Guide to Smart Tea Rooms, Hotels and Inns, stationery inked in blue with a Quimper design, concerning the forthcoming publication of a spiral-bound book of recipes sent by east coast managers, of foods relished by guests -- an enlargement of her annual June pocket guide, with news of the opening of the Buttercup Hill Tea Room, and some information concerning her years at the Patten Free Library in Bath, Maine, a typed letter from the Maine State Library thanking Webber for the Dinner Is Served Cook Book for the Maine Author Collection, and a prepublication, biographical, book review newspaper clipping

Metabolite transport and associated sugar signalling systems underpinning source/ sink interactions

Metabolite transport between organelles, cells and source and sink tissues not only enables pathway co-ordination but it also facilitates whole plant communication, particularly in the transmission of information concerning resource availability. Carbon assimilation is co-ordinated with nitrogen assimilation to ensure that the building blocks of biomass production, amino acids and carbon skeletons, are available at the required amounts and stoichiometry, with associated transport processes making certain that these essential resources are transported from their sites of synthesis to those of utilization. Of the many possible posttranslational mechanisms that might participate in efficient co-ordination of metabolism and transport only reversible thiol-disulphide exchange mechanisms have been described in detail. Sucrose and trehalose metabolism are intertwined in the signalling hub that ensures appropriate resource allocation to drive growth and development under optimal and stress conditions, with trehalose-6-phosphate acting as an important signal for sucrose availability. The formidable suite of plant metabolite transporters provides enormous flexibility and adaptability in inter-pathway coordination and source-sink interactions. Focussing on the carbon metabolism network, we highlight the functions of different transporter families, and the important of thioredoxins in the metabolic dialogue between source and sink tissues. In addition, we address how these systems can be tailored for crop improvement

Global Analysis of Gene Expression Profiles in Developing Physic Nut (Jatropha curcas L.) Seeds

Background: Physic nut (Jatropha curcas L.) is an oilseed plant species with high potential utility as a biofuel. Furthermore, following recent sequencing of its genome and the availability of expressed sequence tag (EST) libraries, it is a valuable model plant for studying carbon assimilation in endosperms of oilseed plants. There have been several transcriptomic analyses of developing physic nut seeds using ESTs, but they have provided limited information on the accumulation of stored resources in the seeds. Methodology/Principal Findings: We applied next-generation Illumina sequencing technology to analyze global gen

Analysis of pressure data with the aquifer influence function

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New Test Conditions Extend Potential For Cetane Rating

The reliability of the cetane rating of a diesel fuel as an indicator of combustion quality has been called into question in recent years, particularly for fuels that are significantly different in composition than nominal diesel fuel. In seeking a way to utilize the large installed base of fuel research engines, changes in apparatus and instrumentation were made to a CFR cetane engine to extend the operating and measurement capabilities of the system. These changes included installation of an inlet air system for enhanced temperature and pressure control, and modern instrumentation to determine combustion characteristics such as ignition delay and combustion period. Results from this preliminary test program indicate that a light load operating condition with cold (15°F) inlet air provides a more critical test than the normal ASTM D-613 test conditions. Tests at this more critical condition raise questions about the relative performance of the secondary reference fuels and real diesel fuels at low temperature and light load conditions. Based on very limited data, a possible fuel ranking procedure is proposed that would include information from these low temperature, light load test conditions. Copyright © 1989 Society of Automotive Engineers, Inc