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Maximum Accumulation (maximum + accumulation)
Selected AbstractsThe accumulation of specific mRNAs following multiple blood meals in Anopheles gambiaeINSECT MOLECULAR BIOLOGY, Issue 1 2005X. Nirmala Abstract One approach to genetic control of transmission of the parasites that cause human malaria is based on expressing effector genes in mosquitoes that disable the pathogens. Endogenous mosquito promoter and other cis -acting DNA sequences are needed to direct the optimal tissue-, stage- and sex-specific expression of the effector molecules. The mRNA accumulation profiles of eight different genes expressed specifically in the midgut, salivary glands or fat body tissues of the malaria vector, Anopheles gambiae, were characterized as a measure of their suitability to direct the expression of effector molecules designed to disable specific stages of the parasites. RT-PCR techniques were used to determine the abundance of the gene products and their duration following multiple blood meals. Transcription from the midgut-expressed carboxypeptidase-encoding gene, AgCP, follows a cyclical, blood-inducible expression pattern with maximum accumulation every 3 h post blood meal. Other midgut-expressed genes encoding a trypsin and chymotrypsin, Antryp2 and Anchym1, respectively, and the fat body-expressed genes, Vg1 and Cathepsin, also show a blood-inducible pattern of expression with maximum accumulation 24 h after every blood meal. Expression of the Lipophorin gene in the fat body and apyrase and D7-related genes (AgApy and D7r2) in the salivary glands is constitutive and not significantly affected by blood meals. Promoters of the midgut- and fat body-expressed genes may lead to maximum accumulation of antiparasite effector molecule transcripts after multiple blood meals. The multiple feeding behaviour of An. gambiae thus can be an advantage to express high levels of antiparasite effector molecules to counteract the parasites throughout most of adult development. [source] The existence of secondary orbital interactionsJOURNAL OF COMPUTATIONAL CHEMISTRY, Issue 1 2007Chaitanya S. Wannere Abstract B3LYP/6-311+G** (and MP2/6-311+G**) computations, performed for a series of Diels-Alder (DA) reactions, confirm that the endo transition states (TS) and the related Cope-TSs are favored energetically over the respective exo -TSs. Likewise, the computed magnetic properties (nucleus-independent chemical shifts and magnetic susceptibililties) of the endo - (as well as the Cope) TS's reveal their greater electron delocalization and greater aromaticity than the exo -TS's. However, Woodward and Hoffmann's original example is an exception: their endo -TS model, involving the DA reaction of a syn - with an anti -butadiene (BD), actually is disfavored energetically over the corresponding exo -TS; magnetic criteria also do not indicate the existence of SOI delocalization in either case. Instead, a strong energetic preference for endo -TSs due to SOI is found when both BDs are in the syn conformations. This is in accord with Alder and Stein's rule of "maximum accumulation of double bonds:" both the dienophile and the diene should have syn conformations. Plots along the IRC's show that the magnetic properties typically are most strongly exalted close to the energetic TS. Because of SOI, all the points along the endo reaction coordinates are more diatropic than along the corresponding exo pathways. We find weak SOI effects to be operative in the endo -TSs involved in the cycloadditions of cyclic alkenes, cyclopropene, aziridine, cyclobutene, and cyclopentene, with cyclopentadiene. While the endo -TSs are only slightly lower in energy than the respective exo -TSs, the magnetic properties of the endo -TS's are significantly exalted over those for the exo -TS's and the Natural Bond Orbitals indicate small stabilizing interactions between the methylene cycloalkene hydrogen orbitals (and lone pairs in case of aziridine) with ,-character and the diene , MOs. © 2006 Wiley Periodicals, Inc. J Comput Chem 2007 [source] Changes in Cell Wall-bound Phenolic Compounds and Lignin in Roots of Date Palm Cultivars Differing in Susceptibility to Fusarium oxysporum f. sp. albedinisJOURNAL OF PHYTOPATHOLOGY, Issue 7-8 2000C. El Modafar The roots of date palm contain four cell wall-bound phenolic acids identified as p -hydroxybenzoic, p -coumaric, ferulic and sinapic acids. The ferulic acid represents the major phenolic compound since it constitutes 48.2,55.8% of cell wall-bound phenolic acids. All these phenolic acids were present in the resistant cultivar (BSTN) and the susceptible cultivar (JHL). However, the pre-infection contents of p -coumaric, ferulic and sinapic acids were greater in the resistant cultivar than in the susceptible one. For the contents of p -hydroxybenzoic acid, there was no significant difference between the resistant cultivar and the susceptible cultivar. Similarly, the pre-infection contents of lignin were approximately equal for both cultivars. Inoculation of the date palm roots by Fusarium oxysporum f. sp. albedinis induced important modifications to the contents of the cell wall-bound phenolic compounds and lignin, which made it possible to distinguish between resistant and susceptible cultivars. The post-infection contents of cell wall-bound phenolic compounds underwent a rapid and intense increase with a maximum accumulation on the tenth day for p -hydroxybenzoic acid (1.54 ,mol/g), p -coumaric acid (2.77 ,mol/g) and ferulic acid (2.64 ,mol/g) and on the fifteenth day for sinapic acid (1.85 ,mol/g). The maximum contents accumulated in the resistant cultivar were greater than those in the susceptible cultivar, namely, 11 times for p -hydroxybenzoic acid, 2.6 times for p -coumaric acid, 1.8 times for ferulic acid and 12.3 times for sinapic acid. In the susceptible cultivar, p -coumaric acid and ferulic acid contents also increased after inoculation although they did not reach the pre-infection contents of the resistant cultivar. The contents of p -hydroxybenzoic acid in the susceptible cultivar roots did not present post-infection modification and those of sinapic acid decreased instead. The lignin contents increased in both cultivars with a maximum accumulation on the fifteenth day. However, the maximum contents accumulated in the resistant cultivar roots were 1.5 times greater than those of the susceptible cultivar. These results showed clear differences between the resistant BSTN and the susceptible JHL cultivars. The implication of cell wall-bound phenolic compounds and lignin in the resistance of date palm to F. oxysporum f. sp. albedinis appears to be dependent on the speed and intensity of their accumulation with greater contents in the first stage of infection. Zusammenfassung Die Wurzeln der Dattelpalme enthalten vier zellwandgebundene Phenolsäuren, die als p -Hydroxybenzoesäure, p- Cumarsäure, Ferulasäure und Sinapinsäure identifiziert wurden. Ferulasäure ist die wichtigste phenolische Verbindung, denn sie stellt 48,2 bi 55,8% der zellwandgebundenen Phenolsäuren. Alle vier Phenolsäuren waren in der resistenten Sorte BSTN und in der anfälligen Sorte JHL vorhanden. Die Gehalte an p -Cumarsäure, Ferulasäure und Sinapinsäure waren vor der Infektion bei der resistenten Sorte jedoch höher als bei der anfälligen Sorte. Hinsichtlich des Gehalts an p -Hydroxybenzoesäure unterschieden sich die resistente und die anfällige Sorte nicht signifikant voneinander. Auch die Ligningehalte vor der Infektion waren bei beiden Sorten ungefähr gleich. Die Inokulation von Dattelpalmenwurzeln mit Fusarium oxysporum f. sp. albedinis induziert wichtige Änderungen der Gehalte an zellwandgebundenen phenolischen Verbindungen und Lignin, was eine Unterscheidung resistenter von anfälligen Sorten ermöglicht. Nach der Infektion nehmen die Gehalte an zellwandgebundenen phenolischen Verbindungen rasch und erheblich zu, mit maximaler Akkumulation am 10. Tag bei p -Hydroxybenzoesäure (1,54 ,mol/g), p -Cumarsäure (2,77 ,mol/g) und Ferulasäure (2,64 ,mol/g) sowie am 15. Tag bei Sinapinsäure (1,85 ,mol/g). Die in der resistenten Sorte akkumulierten maximalen Gehalte waren höher als die maximalen Gehalte der anfälligen Sorte , um das Elffache bei p -Hydroxybenzoesäure, das 2,6-fache bei p -Cumarsäure, das 1,8-fache bei Ferulasäure und das 2,3-fache bei Sinapinsäure. Bei der anfälligen Sorte steigen die Gehalte an p -Cumarsäure und Ferulasäure nach der Inokulation ebenfalls an, bleiben aber niedriger als die Werte der resistenten Sorte vor der Infektion. Der p -Hydroxybenzoesäuregehalt in den Wurzeln der anfälligen Sorte ist nach der Infektion nicht verändert, und der Sinapinsäuregehalt nimmt ab. Der Ligningehalt steigt bei beiden Sorten, mit maximaler Akkumulation am 15. Tag. Der maximale Gehalt in den Wurzeln der resistenten Sorte war jedoch 1,5-mal höher als bei der anfälligen Sorte. Diese Ergebnisse zeigen deutliche Unterschiede zwischen der resistenten Sorte (BSTN) und der anfälligen Sorte (JHL). Die Bedeutung der zellwandgebundenen phenolischen Verbindungen und des Lignins für die Resistenz der Dattelpalme gegen F. oxysporum f. sp. albedinis scheint von der Geschwindigkeit und der Intensität der Akkumulation abzuhängen, wobei die Gehalte im ersten Stadium der Infektion höher sind. [source] Positron emission tomography of [18F]-big endothelin-1 reveals renal excretion but tissue-specific conversion to [18F]-endothelin-1 in lung and liverBRITISH JOURNAL OF PHARMACOLOGY, Issue 4 2010Peter Johnström Background and purpose:, Big endothelin-1 (ET-1) circulates in plasma but does not bind to ET receptors until converted to ET-1 by smooth muscle converting enzymes. We hypothesized that tissue-specific conversion of [18F]-big ET-1 to [18F]-ET-1 could be imaged dynamically in vivo within target organs as binding to ET receptors. Methods:, [18F]-big ET-1 conversion imaged in vivo following infusion into rats using positron emission tomography (PET). Key results:, [18F]-big ET-1 was rapidly cleared from the circulation (t1/2= 2.9 ± 0.1 min). Whole body microPET images showed highest uptake of radioactivity in three major organs. In lungs and liver, time activity curves peaked within 2.5 min, then plateaued reaching equilibrium after 10 min, with no further decrease after 120 min. Phosphoramidon did not alter half life of [18F]-big ET-1 but uptake was reduced in lung (42%) and liver (45%) after 120 min, consistent with inhibition of enzyme conversion and reduction of ET-1 receptor binding. The ETA antagonist, FR139317 did not alter half-life of [18F]-big ET-1 (t1/2= 2.5 min) but radioactivity was reduced in all tissues except for kidney consistent with reduction in binding to ETA receptors. In kidney, however, the peak in radioactivity was higher but time to maximum accumulation was slower (,30 min), which was increased by phosphoramidon, reflecting renal excretion with low conversion and binding to ET receptors. Conclusions and implications:, A major site for conversion was within the vasculature of the lung and liver, whereas uptake in kidney was more complex, reflecting excretion of [18F]-big ET-1 without conversion to ET-1. This article is part of a themed section on Imaging in Pharmacology. To view the editorial for this themed section visit http://dx.doi.org/10.1111/j.1476-5381.2010.00685.x [source] | ||||||||||