Analyse des raum-zeitlichen Zusammentreffens von Amphibien und Landbewirtschaftung als Grundlage für die Ableitung von Strategien zum Amphibienschutz in kleingewässerreichen Ackerbaugebieten

Zusammenfassung Ein großer Teil der Schutzgebiete für gefährdete Amphibienarten (z.B. Kammmolch, Rotbauchunke) befindet sich innerhalb intensiv genutzter Ackerbaugebiete. Das bedeutet, dass die Amphibien auch Ackerflächen für ihre Wanderungen im Frühjahr zu den Laichgewässern und im Spätsommer/Herbst zu den Winterquartieren sowie zwischenzeitlich bei Landaufenthalten nutzen und somit Gefahr laufen, durch landwirtschaftliche Bewirtschaftungsmaßnahmen geschädigt zu werden. In einem am Leibnitz-Zentrum für Agrarlandschaftsforschung durchgeführten Forschungsprojekt (2006-2008) wurden in einem ca. 1.300 ha großen Untersuchungsgebiet mit Hilfe von umfangreichen Amphibienfangeinrichtungen auf Ackerflächen das Raum-Zeit-Verhalten von Amphibienpopulationen, sowie die Bewirtschaftung der betreffenden Ackerflächen erforscht. Anhand der täglich ermittelten Individuen pro Fanggefäß konnten Rückschlüsse auf die Aktivitätsphasen von Amphibien auf Ackerflächen gezogen werden, welche die Grundlage für die Untersuchung der Wahrscheinlichkeit des Zusammentreffens von Amphibien mit landwirtschaftlichen Bewirtschaftungsmaßnahmen bildeten. Es wurde festgestellt, dass Maßnahmen der Bodenbearbeitung die höchste zeitliche Übereinstimmung mit der Aktivität juveniler Tiere haben, die Aktivität adulter Tiere fiel hingegen zeitlich oft mit Maßnahmen des Pflanzenschutzes zusammen. Anhand der Ergebnisse lassen sich Strategien für die Integration des Amphibienschutzes in die ackerbauliche Nutzung ableiten, welche die kurzfristige Unterlassung bestimmter Bewirtschaftungsmaßnahmen in Problemarealen beinhalten, ohne dabei das Betriebsergebnis zu beeinträchtigen. Die dargestellten Untersuchungen bilden die Grundlage für witterungsbasierte Prognosemodelle über das temporäre Auftreten von Amphibienarten auf Ackerflächen. Strategien für die Integration des Amphibienschutzes in die ackerbauliche Nutzung ableiten, welche die kurzfristige Unterlassung bestimmter Bewirtschaftungsmaßnahmen in Problemarealen beinhalten, ohne dabei das Betriebsergebnis zu beeinträchtigen. Die dargestellten Untersuchungen bilden die Grundlage für witterungsbasierte Prognosemodelle über das temporäre Auftreten von Amphibienarten auf Ackerflächen

2-Amino-4-aryl-5-oxo-4,5-dihydropyrano[3,2-c]chromene-3-carbonitriles with Microtubule-Disruptive, Centrosome-Declustering, and Antiangiogenic Effects in vitro and in vivo

A series of fifteen 2‐amino‐4‐aryl‐5‐oxo‐4,5‐dihydropyrano[3,2‐c]chromene‐3‐carbonitriles (1 a–o) were synthesized via a three‐component reaction of 4‐hydroxycoumarin, malononitrile, and diversely substituted benzaldehydes or pyridine carbaldehydes. The compounds were tested for anticancer activities against a panel of eight human tumor cell lines. A few derivatives with high antiproliferative activities and different cancer cell specificity were identified and investigated for their modes of action. They led to microtubule disruption, centrosome de‐clustering and G2/M cell cycle arrest in 518 A2 melanoma cells. They also showed anti‐angiogenic effects in vitro and in vivo

Experimental and Modeling Investigation of the Effectof H2S Addition to Methane on the Ignition and Oxidation at High Pressures

The autoignition and oxidation behavior of CH₄/H₂S mixtures has been studied experimentally in a rapid compression machine (RCM) and a high-pressure flow reactor. The RCM measurements show that the addition of 1% H₂S to methane reduces the autoignition delay time by a factor of 2 at pressures ranging from 30 to 80 bar and temperatures from 930 to 1050 K. The flow reactor experiments performed at 50 bar show that, for stoichiometric conditions, a large fraction of H₂S is already consumed at 600 K, while temperatures above 750 K are needed to oxidize 10% methane. A detailed chemical kinetic model has been established, describing the oxidation of CH₄ and H₂S as well as the formation and consumption of organosulfuric species. Computations with the model show good agreement with the ignition measurements, provided that reactions of H₂S and SH with peroxides (HO₂ and CH₃OO) are constrained. A comparison of the flow reactor data to modeling predictions shows satisfactory agreement under stoichiometric conditions, while at very reducing conditions, the model underestimates the consumption of both H₂S and CH₄. Similar to the RCM experiments, the presence of H₂S is predicted to promote oxidation of methane. Analysis of the calculations indicates a significant interaction between the oxidation chemistry of H₂S and CH₄, but this chemistry is not well understood at present. More work is desirable on the reactions of H₂S and SH with peroxides (HO₂ and CH₃OO) and the formation and consumption of organosulfuric compounds

Advanced Thermally Stable Jet Fuels

The Penn State program in advanced thermally stable jet fuels has five components: 1) development of mechanisms of degradation and solids formation; 2) quantitative measurement of growth of sub-micrometer and micrometer-sized particles during thermal stressing; 3) characterization of carbonaceous deposits by various instrumental and microscopic methods; 4) elucidation of the role of additives in retarding the formation of carbonaceous solids; and 5) assessment of the potential of producing high yields of cycloalkanes and hydroaromatics from coal

Protein Conformational Changes in the Bacteriorhodopsin Photocycle: Comparison of Findings from Electron and X-Ray Crystallographic Analyses

Light-driven conformational changes in the membrane protein bacteriorhodopsin have been studied extensively using X-ray and electron crystallography, resulting in the deposition of >30 sets of coordinates describing structural changes at various stages of proton transport. Using projection difference Fourier maps, we show that coordinates reported by different groups for the same photocycle intermediates vary considerably in the extent and nature of conformational changes. The different structures reported for the same intermediate cannot be reconciled in terms of differing extents of change on a single conformational trajectory. New measurements of image phases obtained by cryo-electron microscopy of the D96G/F171C/F219L triple mutant provide independent validation for the description of the large protein conformational change derived at 3.2 Å resolution by electron crystallography of 2D crystals, but do not support atomic models for light-driven conformational changes derived using X-ray crystallography of 3D crystals. Our findings suggest that independent determination of phase information from 2D crystals can be an important tool for testing the accuracy of atomic models for membrane protein conformational changes

Enhancement of stress tolerance in transgenic tobacco plants constitutively expressing AtIpk2β, an inositol polyphosphate 6-/3-kinase from Arabidopsis thaliana

Inositol phosphates (IPs) and their turnover products have been implicated to play important roles in stress signaling in eukaryotic cells. In higher plants genes encoding inositol polyphosphate kinases have been identified previously, but their physiological functions have not been fully resolved. Here we expressed Arabidopsis inositol polyphosphate 6-/3-kinase (AtIpk2β) in two heterologous systems, i.e. the yeast Saccharomycescerevisiae and in tobacco (Nicotiana tabacum), and tested the effect on abiotic stress tolerance. Expression of AtIpk2β rescued the salt-, osmotic- and temperature-sensitive growth defects of a yeast mutant strain (arg82Δ) that lacks inositol polyphosphate multikinase activity encoded by the ARG82/IPK2 gene. Transgenic tobacco plants constitutively expressing AtIpk2β under the control of the Cauliflower Mosaic Virus 35S promoter were generated and found to exhibit improved tolerance to diverse abiotic stresses when compared to wild type plants. Expression patterns of various stress responsive genes were enhanced, and the activities of anti-oxidative enzymes were elevated in transgenic plants, suggesting a possible involvement of AtIpk2β in plant stress responses

A Quorum Sensing Regulated Small Volatile Molecule Reduces Acute Virulence and Promotes Chronic Infection Phenotypes

A significant number of environmental microorganisms can cause serious, even fatal, acute and chronic infections in humans. The severity and outcome of each type of infection depends on the expression of specific bacterial phenotypes controlled by complex regulatory networks that sense and respond to the host environment. Although bacterial signals that contribute to a successful acute infection have been identified in a number of pathogens, the signals that mediate the onset and establishment of chronic infections have yet to be discovered. We identified a volatile, low molecular weight molecule, 2-amino acetophenone (2-AA), produced by the opportunistic human pathogen Pseudomonas aeruginosa that reduces bacterial virulence in vivo in flies and in an acute mouse infection model. 2-AA modulates the activity of the virulence regulator MvfR (multiple virulence factor regulator) via a negative feedback loop and it promotes the emergence of P. aeruginosa phenotypes that likely promote chronic lung infections, including accumulation of lasR mutants, long-term survival at stationary phase, and persistence in a Drosophila infection model. We report for the first time the existence of a quorum sensing (QS) regulated volatile molecule that induces bistability phenotype by stochastically silencing acute virulence functions in P. aeruginosa. We propose that 2-AA mediates changes in a subpopulation of cells that facilitate the exploitation of dynamic host environments and promote gene expression changes that favor chronic infections

Multiple-Color Optical Activation, Silencing, and Desynchronization of Neural Activity, with Single-Spike Temporal Resolution

The quest to determine how precise neural activity patterns mediate computation, behavior, and pathology would be greatly aided by a set of tools for reliably activating and inactivating genetically targeted neurons, in a temporally precise and rapidly reversible fashion. Having earlier adapted a light-activated cation channel, channelrhodopsin-2 (ChR2), for allowing neurons to be stimulated by blue light, we searched for a complementary tool that would enable optical neuronal inhibition, driven by light of a second color. Here we report that targeting the codon-optimized form of the light-driven chloride pump halorhodopsin from the archaebacterium Natronomas pharaonis (hereafter abbreviated Halo) to genetically-specified neurons enables them to be silenced reliably, and reversibly, by millisecond-timescale pulses of yellow light. We show that trains of yellow and blue light pulses can drive high-fidelity sequences of hyperpolarizations and depolarizations in neurons simultaneously expressing yellow light-driven Halo and blue light-driven ChR2, allowing for the first time manipulations of neural synchrony without perturbation of other parameters such as spiking rates. The Halo/ChR2 system thus constitutes a powerful toolbox for multichannel photoinhibition and photostimulation of virally or transgenically targeted neural circuits without need for exogenous chemicals, enabling systematic analysis and engineering of the brain, and quantitative bioengineering of excitable cells