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Selected AbstractsComplexation and Dynamic Switching Properties of Fluorophore-Appended Resorcin[4]arene CavitandsEUROPEAN JOURNAL OF ORGANIC CHEMISTRY, Issue 5 2010Laura D. Shirtcliff Abstract Fluorophore-appended resorcin[4]arene-based cavitands having pyrene (2) and anthracene (3) moieties attached to the rims were prepared by short synthetic routes. Both undergo reversible temperature- and acid- (CF3COOD) induced vase,,,kite switching as evidenced by 1H NMR spectroscopy. The 1H NMR spectra also suggest that suitably sized solvents, such as [D8]toluene, efficiently solvate the cavity, reducing the conformational flexibility. In [D12]mesitylene, both cavitands undergo remarkably stable host-guest inclusion complexation with cycloalkanes. The larger cavity of 3 preferentially hosts cyclohexane, whereas the smaller cavity of 2 forms the most stable complex with cyclopentane. The propensity for the cavitands to facilitate ,,, stacking between the chromophores was confirmed by both 1H NMR and fluorescence spectroscopy. The interchromophoric interaction is strongly solvent-dependent: ,,, stacking between the pyrene moieties of 2 is not as efficient in [D8]toluene, as it solvates the inner cavity and prevents the two chromophores from approaching each other. Fluorescence studies revealed an unexpectedly large conformational flexibility of the cavitand structures both in the vase and kite forms, which was further confirmed by molecular dynamics simulations. Excimer formation is most preferred in [D12]mesitylene when the cavities are empty, whereas efficient solvation or guest binding in the interior spaces reduces the propensity for excimer formation. The observed high conformational flexibility of the cavitands in solution explains previous differences from the behavior of related systems in the solid state. This study shows that the rigid, perfect vase and kite geometries found for bridged resorcin[4]arene cavitands in the solid state are largely a result of crystal packing effects and that the conformational flexibility of the structures in solution is rather high. [source] Rust severity in bioenergy willow plantations treated with additional nutrientsFOREST PATHOLOGY, Issue 1 2009M. Toome Summary A 3-year field study was carried out to determine the effect of wastewater irrigation and previous differences in mineral fertilization on the occurrence of willow leaf rust (Melampsora epitea). The experiment was conducted in two energy forest plantations: one designed for wastewater purification and the other as a mineral fertilization experiment. The severity of leaf rust on different clones and sites with different treatments was assessed by counting the number of uredinia per leaf unit area. Generally, plants irrigated with wastewater consistently had more leaf rust, irrespective of the study years or willow clones. Previous mineral fertilization had mixed effects on different clones 2 years after the last application. Three years after the last fertilizer application, however, no impact of the treatment on rust disease development was detected. In general, the rust levels differed from year to year probably due to climate. In this study, no correlation was detected between shoot age and rust severity, whereas climate and treatments strongly influenced leaf rust levels on some willow clones. [source] Possible Pleiotropic Effects of Genes Specifying Sedative/Hypnotic Sensitivity to Ethanol on Other Alcohol-Related TraitsALCOHOLISM, Issue 10 2002Jeremy C. Owens Background Initial sensitivity to ethanol is a predictor of alcohol abuse that has been studied extensively in both human and animal populations. Selection for initial sensitivity to the sedative/hypnotic effects of ethanol resulted in the long-sleep and short-sleep lines of mice. Some of the genes selected in these lines could also specify differential responses in other ethanol-related phenotypes and, perhaps, for other drugs of abuse. We assessed congenic mice carrying a single quantitative trait locus (QTL) from the inbred long-sleep (ILS) or inbred short-sleep (ISS) strain on the reciprocal background for a number of ethanol- and pentobarbital-related phenotypes. Methods Each congenic strain was tested for ethanol elimination rates at 4.1 g/kg, ethanol-induced ataxia at 2.0 g/kg, ethanol-induced hypothermia at 4.1 g/kg, and pentobarbital-induced loss of righting reflex (LORR) at 60 mg/kg. Additionally, the ILS.ISS congenics were tested for low-dose ethanol-induced activation (LDA) at five doses ranging from 0.6 to 1.2 g/kg ethanol, and the ISS.ILS congenics were tested for LDA at 1.8 g/kg of ethanol. Results There was little difference in the ethanol elimination rate between congenics and background strains, although a modest sex effect was found, with the females eliminating ethanol more rapidly than the males. We were unable to replicate previous differences found in LDA for the Lore1 congenic on the ISS background, because none of the congenics differed from controls for LDA. Lore5 congenics showed a differential effect of pentobarbital-induced LORR in the expected directions. The Lore1 congenics on the ISS background showed more ethanol-induced ataxia than the ISS controls. Additionally, the hypothermic response seems affected by Lore4 and Lore5 and maybe others. Conclusions At least two regions carrying a QTL specifying sensitivity to high doses of ethanol cospecify altered sensitivity in other measures of alcohol action. Specifically, these QTLs clearly affect ethanol-induced hypothermia and pentobarbital-induced LORR and possibly ethanol-induced ataxia. [source] Differences in hydraulic architecture account for near-isohydric and anisohydric behaviour of two field-grown Vitis vinifera L. cultivars during droughtPLANT CELL & ENVIRONMENT, Issue 8 2003H. R. SCHULTZ ABSTRACT A comparative study on stomatal control under water deficit was conducted on grapevines of the cultivars Grenache, of Mediterranean origin, and Syrah of mesic origin, grown near Montpellier, France and Geisenheim, Germany. Syrah maintained similar maximum stomatal conductance (gmax) and maximum leaf photosynthesis (Amax) values than Grenache at lower predawn leaf water potentials, ,leaf, throughout the season. The ,leaf of Syrah decreased strongly during the day and was lower in stressed than in watered plants, showing anisohydric stomatal behaviour. In contrast, Grenache showed isohydric stomatal behaviour in which ,leaf did not drop significantly below the minimum ,leaf of watered plants. When g was plotted versus leaf specific hydraulic conductance, Kl, incorporating leaf transpiration rate and whole-plant water potential gradients, previous differences between varieties disappeared both on a seasonal and diurnal scale. This suggested that isohydric and anisohydric behaviour could be regulated by hydraulic conductance. Pressure-flow measurements on excised organs from plants not previously stressed revealed that Grenache had a two- to three-fold larger hydraulic conductance per unit path length (Kh) and a four- to six-fold larger leaf area specific conductivity (LSC) in leaf petioles than Syrah. Differences between internodes were only apparent for LSC and were much smaller. Cavitation detected as ultrasound acoustic emissions on air-dried shoots showed higher rates for Grenache than Syrah during the early phases of the dry-down. It is hypothesized that the differences in water-conducting capacity of stems and especially petioles may be at the origin of the near-isohydric and anisohydric behaviour of g. [source] | ||||||||||