(1E,4Z,6E)-5-Hy­droxy-1,7-bis­(2-meth­oxy­phen­yl)-1,4,6-hepta­trien-3-one

In the title compound, C21H20O4, the central hepta­trienone unit is approximately planar, with a maximum atomic deviation of 0.1121 (11) Å; the two benzene rings are twisted with respect to the hepta­trienone mean plane by 2.73 (5) and 29.31 (4)°. The mol­ecule exists in the enol form and the hy­droxy group forms an intra­molecular hydrogen bond with the neighboring carbonyl group. Weak inter­molecular C—H⋯O hydrogen bonding is present in the crystal structure

A sensitive and specific β-alanyl aminopeptidase-activated fluorogenic probe for the detection of Pseudomonas aeruginosa

We report the synthesis of the sensitive and specific fluorogenic self-immolative substrate 8b, which is hydrolzyed by β-alanyl aminopeptidase (BAP), resulting in a 1,6-elimination and the release of the highly fluorescent hydroxycoumarin 6b. This fluorophore 6b is retained within bacterial colonies, so has potential for the detection of P. aeruginosa (a BAP producer); it also has potential in liquid media due to the rapid and strong signal release from the substrate 8b, and lack of self-quenching or photobleaching.NHMR

Managing red alder

Revised November 1995. Reprinted April 1996. Facts and recommendations in this publication may no longer be valid. Please look for up-to-date information in the OSU Extension Catalog: http://extension.oregonstate.edu/catalo

Managing red alder

Published March 1986. Facts and recommendations in this publication may no longer be valid. Please look for up-to-date information in the OSU Extension Catalog: http://extension.oregonstate.edu/catalo

Wolf, Elk, and Aspen Food Web Relationships: Context and Complexity

Like most ecological communities, aspen (Populus tremuloides) forests are influenced by a synergy of bottom-up (resources-driven) and top-down (predator-driven) processes. Since the 1920s, ecologists have observed the decline of many aspen communities throughout the Intermountain West. The extent and possible drivers of this decline are topics of much recent scientific study. In addition to bottom-up effects, which include drought, fire suppression, and disease, ungulate herbivory is a contributing factor. Trophic cascades are ecological relationships in which an apex predator produces strong top-down, direct effects on its prey and indirect changes in faunal and floral communities at lower trophic levels. Apex predators, such as the gray wolf (Canis lupus), have been linked to aspen vigor and recruitment, via trophic cascades mechanisms. Scientists have hypothesized that returning wolves to the landscape enables aspen to recruit into the forest overstory, via the density-mediated and behaviorally-mediated effects of wolves on their ungulate prey, primarily elk (Cervus elaphus). We present a synthesis of scientific findings on this topic, identify trends in the ecological impacts of wolves in aspen communities in a variety of ecosystems, and suggest areas for further investigation. Knowledge gaps include the interaction of top-down (e.g., predators) and bottom-up (e.g., drought, fire, hydrology, logging) effects, and how the ecological context of the interaction affects the outcome. Future horizons involve exploring these food web relationships as a complex of inter-level interactions in a more integrated, empirical manner. We suggest adopting a new standard for the aspen/wolf ecology literature by shifting its emphasis and lexicon from trophic cascades to food web studies. Such an integrated approach can help managers create more resilient aspen communities.Keywords: ungulates, fire, trophic cascade

Managing hardwood stands for timber production

Published March 1986. Facts and recommendations in this publication may no longer be valid. Please look for up-to-date information in the OSU Extension Catalog: http://extension.oregonstate.edu/catalo

Experimental and Theoretical Charge Density Distribution in Pigment Yellow 101

The charge density distribution in 2,2'-Dihydroxy-1,1'-naphthalazine (Pigment Yellow 101; P.Y.101) has been determined using high-resolution X-ray diffraction and multipole refinement, along with density functional theory calculations. Topological analysis of the resulting densities highlights the localisation of single/double bonds in the central C=N-N=C moiety of the molecule in its ground state. The density in the N—N is examined in detail, where we show that very small differences between experiment and theory are amplified by use of the Laplacian of the density. Quantification of hydrogen bonds highlights the importance of the intramolecular N—H…O interaction, known to be vital for retention of fluorescence in the solid state, relative to the many but weak intermolecular contacts located. However, a popular method for deriving H-bond strengths from density data appears to struggle with the intramolecular N—H…O interaction. We also show that theoretical estimation of anisotropic displacements for hydrogen atoms brings little benefit overall, and degrades agreement with experiment for one intra-molecular contact.NH&MR

An analysis of the experimental and theoretical charge density distributions of the piroxicam-saccharin co-crystal and its constituents

Experimental and theoretical charge density analyses of piroxicam (1), saccharin (2) and their 1:1 co-crystal complex (3) have been carried out. Electron density distribution (EDD) was determined through the use of high-resolution single crystal X-ray diffraction and the data were modelled using the conventional multipole model of electron density according to the Hansen-Coppens formalism. A method for optimising the core density refinement of sulfur atoms is discussed, with emphasis on the reduction of residual electron density that is typically associated with this atom. The asymmetric unit of complex (3) contains single molecules of saccharin and the zwitterionic form of piroxicam. These are held together by weak interactions (hydrogen bonds, π-π and van der Waals interactions), ranging in strength from 4 to 160 kJmol-1, working together to stabilise the complex;. analysis of the molecular electrostatic potential (MEP) of the complexes showed electron redistribution within the cocrystal, facilitating the formation of these generally weak interactions. Interestingly, in the zwitterionic form of piroxicam, the charge distribution reveals that the positive and negative charges are not associated with the formal charges normally associated with this description, but are distributed over adjacent molecular fragments. The use of anisotropic displacement parameters (ADPs) for hydrogen atoms in the multipole model was also investigated but no improvement in the quality of the topological analysis was found.The University of Sydney Bridging Support Scheme. The Danish National Research Foundation (Center for Materials Crystallography, DNRF-93

Investigating the role of loop c hydrophilic residue 'T244' in the binding site of ρ1 GABAC receptors via site mutation and partial agonism

The loop C hydrophilic residue, threonine 244 lines the orthosteric binding site of ρ1 GABAC receptors was studied by point mutation into serine, alanine and cysteine, and tested with GABA, some representative partial agonists and antagonists. Thr244 has a hydroxyl group essential for GABA activity that is constrained by the threonine methyl group, orienting it toward the binding site. Significant decreases in activation effects of the studied ligands at ρ1 T244S mutant receptors, suggests a critical role for this residue. Results of aliphatic and heteroaromatic partial agonists demonstrate different pharmacological effects at ρ1 T244S mutant receptors when co-applied with GABA EC50 responses. ρ1 T244A and ρ1 T244C mutant receptors have minimal sensitivity to GABA at high mM concentrations, whereas, the ρ1 WT partial agonists, β-alanine and MTSEA demonstrate more efficacy and potency, respectively, than GABA at these mutant receptors. This study explores the role of Thr244 in the binding of agonists as an initial step during channel gating by moving loop C towards the ligand

Riparian litter inputs to streams in the central Oregon Coast Range

Riparian-zone vegetation can influence terrestrial and aquatic food webs through variation in the amount, timing, and nutritional content of leaf and other litter inputs. We investigated how riparianforest community composition, understory density, and lateral slope shaped vertical and lateral litter inputs to 16 streams in the Oregon Coast Range. Riparian forests dominated by deciduous red alder delivered greater annual vertical litter inputs to streams (504 g m⁻² y⁻¹) than did riparian forests dominated by coniferous Douglas-fir (394 g m⁻² y⁻¹). Deciduous forests also contributed greater lateral litter inputs per meter of stream bank on one side (109 g m⁻¹ y⁻¹) than did coniferous forests (63 g m⁻¹ y⁻¹). Total litter inputs from deciduous forests exceeded those from coniferous forests most strongly in November, coincident with an autumn peak in litter inputs. Lateral litter inputs contributed most to total inputs during winter in both forest types. Annual lateral litter movement increased with slope at deciduous sites, but only in spring/ summer months at coniferous sites. Neither experimental removal of understory vegetation nor installation of mesh fences to block downslope litter movement affected lateral litter inputs to streams, suggesting that ground litter moves <5 m downslope annually. N concentrations of several litter fractions were higher at deciduous sites and, when combined with greater litter amounts, yielded twice as much total litter N flux to streams in deciduous than coniferous sites. The presence of red alder in riparian forests along many small streams of the deeply incised and highly dendritic basins of the Oregon Coast Range enhances total fluxes and seasonality of litter delivery to both terrestrial and aquatic food webs in this region and complements the shade and large woody debris provided by large coniferous trees.Keywords: Season, Slope, Douglas-fir, Riparian forest, Red alder, Stream, nitrogen, Understory, Litte