FOREST PATHOLOGY, Issue 4 2006
Alemu Gezahgne
Summary Eucalyptus spp. are among the most widely planted exotic trees in Ethiopia. Several damaging leaf pathogens are known from Eucalyptus spp. worldwide. Of these, Mycosphaerella spp. are among the most important, causing the disease known as Mycosphaerella leaf disease (MLD). Characteristic symptoms of MLD include leaf spot, premature defoliation, shoot and twig dieback. Recent disease surveys conducted in Ethiopian Eucalyptus plantations have revealed disease symptoms similar to those caused by Mycosphaerella spp. These symptoms were restricted to E. globulus trees growing in several localities in south, south western and western Ethiopia. The aim of this study was to identify the fungi associated with this disease. This was achieved by examining ascospore germination patterns, anamorph associations and sequence data from the Internal Transcribed Spacer (ITS) region of the rRNA operon, for representative isolates. Several different ascospore germination patterns were observed, suggesting that more than one species of Mycosphaerella is responsible for MLD on E. globulus in Ethiopia. Analysis of sequence data showed that three Mycosphaerella spp., M. marksii, M. nubilosa and M. parva were present. This is the first report of these three species from Ethiopia and represents a valuable basis on which to build further studies in the region. Résumé Les Eucalyptus comptent parmi les essences d'arbres exotiques les plus plantées en Ethiopie. Plusieurs pathogènes foliaires sont connus dans le monde pour occasionner des dégâts sur Eucalyptus. Parmi ceux-ci, les espèces de Mycosphaerella sont parmi les plus importantes, causant la maladie connue comme Maladie Foliaire àMycosphaerella (MFM, MLD en anglais). Les symptômes caractéristiques de la MFM comprennent des taches foliaires, une défoliation précoce et des dépérissements de pousses et de rameaux. Des campagnes de surveillance menées récemment dans les plantations éthiopiennes d'Eucalyptus ont révélé la présence de tels symptômes. Ces symptômes sont uniquement observés sur E. globulus dans plusieurs localités du sud, sud-ouest et ouest de l'Ethiopie. L'objectif de cette étude était d'identifier les champignons associés à cette maladie. Pour cela, des isolats représentatifs ont étéétudiés pour les modalités de germination des ascospores, les anamorphes associés ainsi que les données de séquence de la région ITS de l'opéron ADNr. Différentes modalités de germination des ascospores ont été observées, suggérant que plusieurs espèces de Mycosphaerella seraient associées à la MFM sur E. globulus en Ethiopie. L'analyse des données de séquence a montré la présence de 3 espèces : M. marksii, M. nubilosa et M. parva. Ceci constitue la première mention de ces 3 espèces en Ethiopie et une première étape pour envisager d'autres études dans cette région. Zusammenfassung Eucalyptus -Arten sind die am häufigsten angepflanzten exotischen Bäume in Äthiopien. An Eucalyptus kommen verschiedene Blattkrankheiten vor, wobei die Mycosphaerella -Arten als Verursacher der Mycosphaerella -Blattkrankheit (MLD) am bedeutendsten sind. Charakteristische Symtpome der MLD sind Blattnekrosen und vorzeitiger Blattfall sowie Trieb- und Zweigsterben. Bei der Inventur von Krankheiten in äthiopischen Eucalyptusplantagen wurden Symptome entdeckt, die denen von Mycosphaerella spp. ähnlich waren. Diese traten nur an E. globulus lokal in S-, SW- und W-Äthiopien auf. Ziel dieser Untersuchung war es, die damit assoziierten Pilze zu identifizieren. Hierzu wurde an repräsentativen Isolaten das Keimverhalten der Ascosporen, das Vorkommen von Anamorphen und die ITS-Sequenz des rRNA-Operons untersucht. Es wurden verschiedene Keimungstypen der Ascosporen beobachtet, was darauf schliessen liess, dass mehr als eine Mycosphaerella -Art für die Krankheit an E. globulus in Äthiopien verantwortlich ist. Anhand der Sequenzen wurden M. marksii, M. nubilosa und M. parva identifiziert. Dies ist der Erstnachweis für diese drei Arten in Äthiopien und eine Grundlage für weitere Studien. [source]

Electronic Decoupling of Aromatic Molecules from a Metal by an Atomically Thin Organic Spacer,

ADVANCED MATERIALS, Issue 23 2008
Roman Forker
Electronic coupling effects of organic adsorbates to metallic surfaces are examined optically. Covering a Au(111) substrate with an ultrathin (,0.3 nm) nanographene-like layer of flat lying molecules leads to decoupling of further molecular layers to a large extent. Our work suggests that not only inorganic salts or oxides can be used as insulating spacers but also particular organic monolayers. [source]

Photoluminescence Quenching Control in Quantum Dot,Carbon Nanotube Composite Colloids Using a Silica-Shell Spacer,

ADVANCED MATERIALS, Issue 4 2006
M. Grzelczak
One-dimensional nanocomposite colloids are prepared by means of electrostatic self-assembly of CdTe nanocrystals on both carbon nanotubes (CNTs) and silica-coated CNTs (see Figure). The dense coverage of these linear nanoparticle assemblies minimizes the spacing between the nanocrystals, thereby facilitating efficient electronic and energy transfer along the nanotubes. [source]

Elucidation of Architectural Requirements from a Spacer in Supported Proline-Based Catalysts of Enantioselective Aldol Reaction

ADVANCED SYNTHESIS & CATALYSIS (PREVIOUSLY: JOURNAL FUER PRAKTISCHE CHEMIE), Issue 1-2 2009
Kerem Goren
Abstract In order to delineate the properties of the spacer architecture responsible for the strong positive dendritic effect exhibited by polymer-supported proline-based catalysts, we prepared two series of polystyrene-bound model catalysts. The first series was based on a linear and partially dendritic spacers (of reduced branching and valency) imitating the length of the second generation spacer, while the second series was based on the first generation dendron spacer with one functional (proline-terminated) and one non-functional arm. Comparative studies of the model and original (fully dendritic) catalysts in the asymmetric aldol reaction of aromatic aldehydes with acetone disclose the features characteristic to the dendritic architecture, such as proximity between the terminal catalytic units and enhanced branching, as crucial for inducing higher yield and enantioselectivity in catalysis. [source]

A SYSTEMATIC STUDY OF GIGAR-TINACEAE FROM PACIFIC NORTH AMERICA BASED ON MOLECULAR AND MORPHOLOGICAL EVIDENCE

JOURNAL OF PHYCOLOGY, Issue 2000
J.R. Hughey
Greater than 50 species of Gigartinaceae have been described from Pacific North America, about half of which are currently recognized. Although the family is treated extensively in the taxonomic literature, many of the species are still confused and a comprehensive revision is required. We sequenced the rbcL (RuBisCO) gene and ITS (Internal Transcribed Spacer) 1, 2, and 5.8S regions from a large number of recent collections and identified a discrete of number data sets. These were analysed in comparison with the morphological evidence for each of the taxa. Uncertain of the possibility that our operational taxonomic units may not correspond to the types, we developed a protocol for isolating PCR-friendly DNA from herbarium specimens, some reaching back as far as 1670. The DNA profiles of types and historically important specimens were compared to those for recently collected silica gel-dried and formalin-fixed material and assigned correct names. Species studied ranged from Alaska to Mexico and the Gulf of California and were compared to outgroup taxa from Pacific South America and the Southern Ocean. Particular attention was paid to variations in morphology as they relate to habitat with emphasis on the presence or absence of different morphological forms among sympatric and allopatric populations. We recognize 10 species in Chondracanthus (including one new combination and one new species) and 16 species in Mazzaella (including two new combinations and two new species). Finally, we tested a phylogenetic hypothesis inferred for the Gigartinaceae from rbcL sequences for congruence with one generated from ITS sequences. [source]

Novel Triaromatic Ester Mesogenic Liquid Crystalline Epoxy Resin Containing Both Methyl Substituent and Ethoxy Flexible Spacer: Synthesis and Curing

MACROMOLECULAR CHEMISTRY AND PHYSICS, Issue 11 2008
Guo-dong Liu
Abstract A novel triaromatic ester liquid crystalline epoxy resin (LCER) that contains both a methyl substituent and an ethoxy flexible spacer, p -methylphenylene di{4-[(2,3-epoxypropoxy)ethoxy]benzoate} (MPEPEB), has been synthesized. The mesotropic property has been investigated by differential scanning calorimetry (DSC) and polarized light optical microscopy (POM). MPEPEB shows a lower melting temperature at 78.7,°C and a broad nematic mesophase temperature range of about 55,°C. Meanwhile MPEPEB shows a mesophase to ,50,°C upon cooling. The curing behavior of MPEPEB with 2,6-diamino-3,5-diethyltoluene (DAE) has been investigated by means of DSC and POM during isothermal and dynamic processes. Although there is little difference between the activation energies obtained from the kinetic data, a marked difference is found between the isothermal and dynamic investigation. The curing reaction in the isothermal investigation roughly obeys n- th order kinetics, while two exothermal peaks appear in the dynamic DSC curves of MPEPEB/DAE. A comparison of the isothermal and dynamic data shows that the curing rate is not a unique function of temperature and curing degree. The cured networks have lower glass temperatures and show a mesophase at room temperature which disappears at about 86,88,°C. [source]

Inhalationstherapie bei Hustenerkrankungen: Methoden und Techniken.

PHARMAZIE IN UNSERER ZEIT (PHARMUZ), Issue 6 2008
Wirkungsvolle Hustentherapie mit geeigneten Inhalationsgeräten
In der Pneumologie spielt die Inhalationstherapie von Atemwegserkrankungen mit geeigneten Inhalationsgeräten und atemwegsgängigen Medikamenten eine bedeutungsvolle Rolle. Ein ausschließlich für alle Altersgruppen zu empfehlendes Inhalationsgerät gibt es nicht, vielmehr muss je nach Alter ein geeignetes Inhalationsinstrument ausgewählt werden. Es sollte leicht zu handhaben, gut pflegbar und transportabel sein und keine zu großen Anforderungen an Koordination und Compliance stellen. Gründliche Unterrichtungen über die Zielsetzung der Therapie, Applikationsform und Behandlungsdauer sind eminent wichtig. Frustrationen und Misserfolge durch ineffiziente Inhalationstherapien sind durch regelmäßige Schulungen und Kontrolldemonstrationen zu korrigieren. Bei konsequenter praktischer Umsetzung ist eine wirkungsvolle Inhalationstherapie in allen Altersgruppen gut möglich. Dies beinhaltet nicht zuletzt auch den Einsatz topisch inhalierbarer Kortikosteroide über Dosieraerosole mit ventilgesteuerten Spacern selbst im Säuglings- und Kleinkindesalter. Kinder sollten ermutigt werden, Dosieraerosole mit einem vorgeschalteten Spacersystem über den Mund zu inhalieren, höhere Medikamentendepositionen werden hierdurch erreicht. Eine Gesichtsmaske für Säuglinge und Kleinkinder erleichtert die Behandlung auch unter dem Aspekt, dass Wirkverluste einzukalkulieren sind. Mit dem Einsatz effizienter Spacer- und Trockenpulver-Inhaliersysteme hat sich die Notwendigkeit der Ausstattung mit Feuchtverneblern vermindert. Druckluftgesteuerte Inhaliersysteme, verbesserte Pulverapplikatoren, fein- und langsam vernebelnde Lösungsaerosole sind neu eingeführt worden. Dosimetrisch gesteuerte und atemzugverstärkte Vernebler erhöhen bei kontrollierter Atmung nachhaltig die Wirksamkeit und Lungendeposition, so dass Patienten mit schweren chronischen Lungenkrankheiten auch mit dosiskritischen Medikamenten wirkungsvoll behandelt werden können. Sehr intensiv wird an neuen Methoden zur Erzeugung ultrafeiner Aerosole wie auch an Aerosolen selbst geforscht. Dies wird die Lebensperspektive chronisch atemwegskranker Patienten durch innovative Inhalationsmethoden auch in Zukunft erheblich verbessern. [source]

Polyfluorophores on a DNA Backbone: Sensors of Small Molecules in the Vapor Phase,

ANGEWANDTE CHEMIE, Issue 39 2010
Dr. Florent Samain
Immer die richtige Antwort: An Polyethylenglycol-Polystyrol-Kügelchen konjugierte Oligodesoxyfluoroside (ODFs) wurden als Fluoreszenzsensoren für organische Dämpfe genutzt (siehe Bild). Die ODFs , DNA-artige Oligomere, in denen Fluorophor-, Spacer- und Quencher-Einheiten die DNA-Basen ersetzen , waren ausreichend elektronisch verschieden, um deutlich unterschiedlich auf chemisch verschiedene flüchtige organische Verbindungen zu reagieren. [source]

Synthesis and Conformational Behavior of New Intra-annularly Linked Cyclophane Possessing a 1,6-Dioxahexa-2,4-diyne Spacer.

CHEMINFORM, Issue 1 2003
Perumal Rajakumar
Abstract For Abstract see ChemInform Abstract in Full Text. [source]

ChemInform Abstract: New Polymer-Supported Chiral Phase-Transfer Catalysts in the Asymmetric Synthesis of ,-Amino Acids: The Role of a Spacer.

CHEMINFORM, Issue 36 2001
Baptiste Thierry
Abstract ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 100 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a "Full Text" option. The original article is trackable via the "References" option. [source]

Structural and Nonlinear Optical Properties of Aligned Heterotrinuclear [RuII -(Spacer)-MII -(Spacer)-RuII] Complexes (M=Pd, Pt; spacer=4-ethynylpyridine)

CHEMISTRY - AN ASIAN JOURNAL, Issue 6 2009
Qingchun Ge
Abstract Optical alloy: "Linear" heterotrinuclear assemblies, with the metals separated by 4-ethynylpyridine spacers [RuCp(CCpy-4)(dppf)]2[MCl2] (M=Pd, Pt), have been structurally identified. They are electrochemically active and show good cubic nonlinear optical responses. Lewis addition between the metalloligand [RuCp(CCpy-4)(dppf)] (1) (dppf=(C5H4PPh2)2Fe) and MCl2(CH3CN)2 gives [RuCp(CCpy-4)(dppf)]2[MCl2] (M=Pd (2) and Pt (3)), all of which have been spectroscopically and crystallographically characterized. The mixed-metal adducts show the d6 -d8 -d6 metal alignment maintained by the trans disposition of the directionally rigid 4-ethynylpyridine at the centrosymmetric square-planar metal center. Electrochemical studies of these and the related known complexes trans -[RuCl(CCpy-4)(dppm)2] (4) and [trans -RuCl(CCpy-4)(dppm)2]2[MCl2] (dppm=Ph2PCH2PPh2) (M=Pd (5) and Pt (6)) suggest that the spacer-linked heterotrinuclear network is able to stabilize the oxidized RuIII better than the metalloligand precursor. Cubic nonlinear optical responses are also generally higher for the heterometallic complexes. The ,real value of the PdRu2 dppm complex 5 is among the largest for linear organometallic complexes. [source]

Photoinduced Energy- and Electron-Transfer Processes in Dinuclear RuII,OsII, RuII,OsIII, and RuIII,OsII Trisbipyridine Complexes Containing a Shape-Persistent Macrocyclic Spacer

CHEMPHYSCHEM, Issue 1 2006
Margherita Venturi Prof.
Abstract The PF6,salt of the dinuclear [(bpy)2Ru(1)Os(bpy)2]4+complex, where 1 is a phenylacetylene macrocycle which incorporates two 2,2,-bipyridine (bpy) chelating units in opposite sites of its shape-persistent structure, was prepared. In acetonitrile solution, the Ru- and Os-based units display their characteristic absorption spectra and electrochemical properties as in the parent homodinuclear compounds. The luminescence spectrum, however, shows that the emission band of the RuIIunit is almost completely quenched with concomitant sensitization of the emission of the OsIIunit. Electronic energy transfer from the RuIIto the OsIIunit takes place by two distinct processes (ken=2.0×108and 2.2×107s,1at 298 K). Oxidation of the OsIIunit of [(bpy)2Ru(1)Os (bpy)2]4+by CeIVor nitric acid leads quantitatively to the [(bpy)2RuII(1)OsIII(bpy)2]5+complex which exhibits a bpy-to-OsIIIcharge-transfer band at 720 nm (,max=250,M,1cm,1). Light excitation of the RuIIunit of [(bpy)2RuII(1)OsIII(bpy)2]5+is followed by electron transfer from the RuIIto the OsIIIunit (kel,f=1.6×108and 2.7×107s,1), resulting in the transient formation of the [(bpy)2RuIII(1)OsII(bpy)2]5+complex. The latter species relaxes to the [(bpy)2RuII(1)OsIII(bpy)2]5+one by back electron transfer (kel,b=9.1×107and 1.2×107s,1). The biexponential decays of the [(bpy)2*RuII(1)OsII(bpy)2]4+, [(bpy)2*RuII(1)OsIII(bpy)2]5+, and [(bpy)2RuIII(1)OsII(bpy)2]5+species are related to the presence of two conformers, as expected because of the steric hindrance between hydrogen atoms of the pyridine and phenyl rings. Comparison of the results obtained with those previously reported for other Ru,Os polypyridine complexes shows that the macrocyclic ligand 1 is a relatively poor conducting bridge. [source]

Genetic Identification of Pelagic Shark Body Parts for Conservation and Trade Monitoring

CONSERVATION BIOLOGY, Issue 4 2002
Mahmood Shivji
Difficulties with the identification of many commonly fished sharks and their body parts has resulted in a global dearth of catch and trade information, making reliable assessment of exploitation effects and conservation needs for individual species nearly impossible. We developed and tested a highly streamlined molecular genetic approach based on species-specific, polymerase-chain-reaction primers in an eight-primer multiplex format to discriminate simultaneously between body parts from six shark species common in worldwide pelagic fisheries. The species-specific primers are based on DNA sequence differences among species in the nuclear ribosomal internal transcribed spacer 2 locus. The primers and multiplex format accurately and sensitively distinguished samples from each of three lamnid ( Isurus oxyrinchus, Isurus paucus, and Lamna nasus) and three carcharhinid ( Prionace glauca, Carcharhinus obscurus, and Carcharhinus falciformis) species from all but one other shark species encountered in the North Atlantic fishery. Furthermore, the three lamnid primers were robust enough in their discriminatory power to be useful for species diagnosis on a global scale. Preliminary testing of dried fins from Asian and Mediterranean commercial markets suggests that our genetic approach will be useful for determining the species of origin of detached fins, thus allowing the monitoring of trade in shark fins for conservation assessment. Our approach will also facilitate detection of products from protected and other at-risk shark species and may prove useful as a model for development of the high-throughput, genetic, species-diagnosis methods typically required in conservation and management contexts. Resumen: La conservación y manejo de tiburones fundamentado a nivel de especie es una necesidad imperativa debido a la creciente demanda de aletas de tiburón y el reconocimiento de que las especies individuales de tiburones responden de manera distinta a la explotación. Las dificultades para la identificación de muchos tiburones capturados comúnmente, así como de partes de su cuerpo, han resultado en una escasez global de información sobre capturas y comercialización, haciendo casi imposible el poder realizar evaluaciones de los efectos de la explotación y de las necesidades de conservación. Desarrollamos y evaluamos un método altamente estilizado de genética molecular basado en detonadores de la reacción en cadena de la polimerasa, especie-específicos, en un formato múltiple de ocho detonadores para discriminar simultáneamente entre las partes del cuerpo de seis especies de tiburones provenientes de pesquerías pelágicas mundiales comunes. Los detonadores especie-específicos están basados en diferencias en las secuencias de ADN entre especies del locus espaciador 2 nuclear, ribosomal, transcrito. Los detonadores y el formato múltiple distinguen muestras con precisión y sensitividad de cada uno de los tres lámnidos ( Isurus oxyrinchus, Isurus paucus y Lamna nasus) y tres especies de carcarínidos ( Prionace glauca, Carcharhinus obscurus y Carcharhinus falciformis) especies todas encontradas en las pesquerías de Norteamérica, excepto una. Mas aún, los detonadores de los tres lamnidos fueron lo suficientemente robustos en su poder discriminante como para ser usados para el diagnóstico de especies a escala mundial. Las pruebas preliminares de aletas secas de los mercados comerciales de Asia y el Mediterráneo sugieren que nuestro método genético puede ser útil para determinar la especie de origen de las aletas separadas, permitiendo así usar el monitoreo de las aletas de tiburón para evaluaciones de conservación. Nuestro método también podría facilitar la detección de productos provenientes de especies protegidas o en riesgo y podría resultar útil como un modelo para el desarrollo de métodos genéticos de alto rendimiento para el diagnóstico de especies, métodos típicamente requeridos en los contextos de conservación y manejo. [source]

Range size, taxon age and hotspots of neoendemism in the California flora

DIVERSITY AND DISTRIBUTIONS, Issue 3 2010
Nathan J. B. Kraft
Abstract Aim, Sustaining biological diversity requires the protection of the ecological, evolutionary and landscape-level processes that generate it. Here, we identify areas of high neoendemism in a global diversity hotspot, the California flora, using range size data and molecular-based estimates of taxon age. Location, California, USA. Methods, We compiled distribution and range size data for all plant taxa endemic to California and internal transcribed spacer (ITS)-based age estimates for 337 putative neoendemics (15% of the endemic flora). This information was combined to identify areas in the state with high proportions of young and restricted-range taxa. We overlaid the distribution of neoendemic hotspots on maps of currently protected lands and also explored correlations between our diversity measures and climate. Results, The central coast of California, the Sierra Nevada and the San Bernardino Range contained endemics with the most restricted distributions on average, while areas in the Desert and Great Basin provinces found within the state were composed of the youngest neoendemics on average. Diversity measures that took age and range size into account shifted the estimate of highest endemic diversity in the state towards the Desert and Great Basin regions relative to simple counts of endemic species richness. Our diversity measures were poorly correlated with climate and topographic heterogeneity. Main conclusions, Substantial portions of California with high levels of plant neoendemism fall outside of protected lands, indicating that additional action will be needed to preserve the geographic areas apparently associated with high rates of plant diversification. The neoendemic flora of the deserts appears particularly young in our analyses, which may reflect the relatively recent origin of desert environments within the state. [source]

Subpopulations of Cryptocephalus beetles (Coleoptera: Chrysomelidae): geographically close but genetically far

DIVERSITY AND DISTRIBUTIONS, Issue 1 2003
R. W. Piper
Abstract. The leaf beetles Cryptocephalus coryli, C. decemmaculatus and C. nitidulus are of conservation concern and are included on the UK Biodiversity Action Plan. The distinctiveness of the disjunct remaining populations of these beetles was compared to that of more continuously distributed Cryptocephalus species. This was carried out with a view to defining evolutionary significant units (ESUs) in the rare species. A portion of the cytochrome b gene, an intergenic spacer and partial tRNA was analysed from 93 specimens of Cryptocephalus beetle (Coleoptera: Chrysomelidae). Considerable sequence divergence was apparent in all the species, even at an intersite scale when the distances between sampled localities were very small (< 1 km). Intrapopulation, intersite and interpopulation divergence observed in the rare species was reflected in the species that have a more continuous distribution, implying that dispersal ability in these species is poor and gene flow can be impeded by relatively trivial barriers to dispersal. The evidence suggests that the disjunct populations of the rare Cryptocephalus species can, tentatively, be considered as ESUs. This has important implications for management strategies and reintroductions. [source]

Hantzsch 1,4-dihydropyridines containing a nitrooxyalkyl ester moiety to study calcium channel antagonist structure,activity relationships and nitric oxide release

DRUG DEVELOPMENT RESEARCH, Issue 4 2000
Jeffrey-Tri Nguyen
Abstract A group of 3-nitrooxyalkyl 5-alkyl 1,4-dihydro-2,6-dimethyl-4-(pyridyl)-3,5-pyridinedicarboxylates were prepared using a modified Hantzsch reaction that involved the condensation of a nitrooxyalkyl acetoacetate with an alkyl 3-aminocrotonate and a pyridinecarboxaldehyde. 1H NMR nuclear Overhauser enhancement (nOe) studies for 3-(3-nitrooxypropyl) 5-isopropyl 1,4-dihydro-2,6-dimethyl-4-(2-pyridyl)-3,5-pyridinedicarboxylate (17) indicates a predominant rotamer exists in solution where the pyridyl nitrogen atom is orientated above the 1,4-DHP ring system, and the pyridyl nitrogen atom is antiperiplanar to the 1,4-DHP ring H-4 proton. Variable temperature 1H NMR studies (,30 to +60°C) showed the 1,4-DHP NH proton in 17 is H-bonded in CHCl3 solution. This interaction is believed to be due to intermolecular H-bonding between the pyridyl nitrogen free electron pair and the 1,4-DHP NH proton. In vitro calcium channel antagonist (CCA) activities were determined using a muscarinic-receptor-mediated Ca+2 -dependent contraction of guinea pig ileal longitudinal smooth muscle assay. This class of compounds exhibited lower CCA activity (IC50 = 5.3 × 10,6 to 3.5 × 10,8 M range) than the reference drug nifedipine (IC50 = 1.4 × 10,8 M). For compounds having C-3 ,CH2CH2ONO2 and C-4 pyridyl substituents, the C-5 alkyl was a determinant of CCA (i -Pr > the approximately equipotent i -Bu, t -Bu, and Et analogs). The point of attachment of the isomeric C-4 pyridyl substituent was a determinant of CCA when C-3 ,CH2CH2ONO2 and C-5 i -Pr substituents were present providing the potency profile 2-pyridyl , 3-pyridyl > 4-pyridyl. CCA with respect to the C-3 nitrooxyalkyl substituent was inversely dependent on the length of the alkyl spacer. The percent nitric oxide (·NO) released in vitro by this group of compounds (range of 0.03,0.43%/ONO2 group), quantified as nitrite by reaction with the Griess reagent, was lower than that for the reference drug glycerol trinitrate (3.81%/ONO2 group). Nitric oxide release studies showed that the %·NO released was dependent on the number of ONO2 groups/molecule. A QSAR study for this group of compounds showed a correlation between the specific polarizability descriptor (SpPol) and %·NO release. Drug Dev. Res. 51:233,243, 2000. © 2001 Wiley-Liss, Inc. [source]

Enantioseparation of amino acids, ,-hydroxy acids, and dipeptides by ligand-exchange CEC using silica-based chiral stationary phases

ELECTROPHORESIS, Issue 16 2009
Elfriede Pittler
Abstract This work deals with the application of silica-based ligand-exchange chiral stationary phases (CSPs) for the enantioseparation of underivatised amino acids, ,-hydroxy acids, and dipeptides with packed CEC. Two different possibilities of preparing silica-based CSPs are presented. One phase contains L -4-hydroxyproline chemically bonded via a spacer to 3,,m silica material. The other approach makes use of N -decyl- L -4-hydroxyproline dynamically coated on a reversed-phase packed capillary. Dynamical coating of reversed-phase material represents a simple alternative to prepare CSP. A comparison of the chemically bonded phase with the dynamically coated CSP by means of resolution of complex-forming analytes is presented. The chemically bonded phase was found to be superior to the dynamically coated phase in terms of resolution of amino acids and dipeptides. However, the dynamically coated CSP was found to be especially suitable for the separation of ,-hydroxy acids. Both techniques are applicable for enantiomer purity tests. [source]

Naturally occurring egg parasitoids of the genus Trichogramma (Hymenoptera: Trichogrammatidae) in a pomegranate orchard in Tunisia

ENTOMOLOGICAL SCIENCE, Issue 1 2010
Ines KSENTINI
Abstract Four Trichogramma species were found in a pomegranate orchard in Gabès, an arid region of Tunisia, from parasitized eggs of Ectomyelois ceratoniae Zeller (Lepidoptera: Pyralidae), an economically important insect pest. Identification based on assessment of male genitalia and internal transcribed spacer 2 (ITS2) sequences showed that they were T. bourarachae Pintureau and Babault, 1988, T. oleae Voegelé and Pointel, 1979, T. cacoeciae Marchal, 1927 and T. evanescens Westwood, 1833. Trichogramma evanescens is reported for the first time in Tunisia. Trichogramma cacoeciae was the largely dominant species in the analyzed samples, whereas T. bourarachae was present in a minor portion of 1.38%. The implications of these results for attempts at controlling E. ceratoniae are discussed. [source]

Large-scale distribution and activity patterns of an extremely low-light-adapted population of green sulfur bacteria in the Black Sea

ENVIRONMENTAL MICROBIOLOGY, Issue 5 2010
Evelyn Marschall
Summary The Black Sea chemocline represents the largest extant habitat of anoxygenic phototrophic bacteria and harbours a monospecific population of Chlorobium phylotype BS-1. High-sensitivity measurements of underwater irradiance and sulfide revealed that the optical properties of the overlying water column were similar across the Black Sea basin, whereas the vertical profiles of sulfide varied strongly between sampling sites and caused a dome-shaped three-dimensional distribution of the green sulfur bacteria. In the centres of the western and eastern basins the population of BS-1 reached upward to depths of 80 and 95 m, respectively, but were detected only at 145 m depth close to the shelf. Using highly concentrated chemocline samples from the centres of the western and eastern basins, the cells were found to be capable of anoxygenic photosynthesis under in situ light conditions and exhibited a photosynthesis,irradiance curve similar to low-light-adapted laboratory cultures of Chlorobium BS-1. Application of a highly specific RT-qPCR method which targets the internal transcribed spacer (ITS) region of the rrn operon of BS-1 demonstrated that only cells at the central station are physiologically active in contrast to those at the Black Sea periphery. Based on the detection of ITS-DNA sequences in the flocculent surface layer of deep-sea sediments across the Black Sea, the population of BS-1 has occupied the major part of the basin for the last decade. The continued presence of intact but non-growing BS-1 cells at the periphery of the Black Sea indicates that the cells can survive long-distant transport and exhibit unusually low maintenance energy requirements. According to laboratory measurements, Chlorobium BS-1 has a maintenance energy requirement of ,1.6,4.9·10,15 kJ cell,1 day,1 which is the lowest value determined for any bacterial culture so far. Chlorobium BS-1 thus is particularly well adapted to survival under the extreme low-light conditions of the Black Sea, and can be used as a laboratory model to elucidate general cellular mechanisms of long-term starvation survival. Because of its adaptation to extreme low-light marine environments, Chlorobium BS-1 also represents a suitable indicator for palaeoceanography studies of deep photic zone anoxia in ancient oceans. [source]

Testing for endemism, genotypic diversity and species concepts in Antarctic terrestrial microalgae of the Tribonemataceae (Stramenopiles, Xanthophyceae)

ENVIRONMENTAL MICROBIOLOGY, Issue 3 2009
Nataliya Rybalka
Summary The genetic diversity of all available culture strains of the Tribonemataceae (Stramenopiles, Xanthophyceae) from Antarctica was assessed using the chloroplast-encoded psbA /rbcL spacer region sequences, a highly variable molecular marker, to test for endemism when compared with their closest temperate relatives. There was no species endemic for Antarctica, and no phylogenetic clade corresponded to a limited geographical region. However, species of the Tribonemataceae may have Antarctic populations that are distinct from those of other regions because the Antarctic strain spacer sequences were not identical to sequences from temperate regions. Spacer sequences from five new Antarctic isolates were identical to one or more previously available Antarctic strains, indicating that the Tribonemataceae diversity in Antarctic may be rather limited. Direct comparisons of the spacer sequences and phylogenetic analyses of the more conserved rbcL gene revealed that current morphospecies were inadequate to describe the actual biodiversity of the group. For example, the genus Xanthonema, as currently circumscribed, was paraphyletic. Fortunately, the presence of distinctive sequence regions within the psbA/rbcL spacer, together with differences in the rbcL phylogeny, provided significant autoapomorphic criteria to re-define the Tribonemataceae species. [source]

Soils of a Mediterranean hot spot of biodiversity and endemism (Sardinia, Tyrrhenian Islands) are inhabited by pan-European, invasive species of Hypocrea/Trichoderma

ENVIRONMENTAL MICROBIOLOGY, Issue 1 2009
Quirico Migheli
Summary We have used a Mediterranean hot spot of biodiversity (the Island of Sardinia) to investigate the impact of abiotic factors on the distribution of species of the common soil fungus Trichoderma. To this end, we isolated 482 strains of Hypocrea/Trichoderma from 15 soils comprising undisturbed and disturbed environments (forest, shrub lands and undisturbed or extensively grazed grass steppes respectively). Isolates were identified at the species level by the oligonucleotide BarCode for Hypocrea/Trichoderma (TrichOKEY), sequence similarity analysis (Trichoblast) and phylogenetic inferences. The majority of the isolates were positively identified as pan-European and/or pan-global Hypocrea/Trichoderma species from sections Trichoderma and Pachybasium, comprising H. lixii/T. harzianum, T. gamsii, T. spirale, T. velutinum, T. hamatum, H. koningii/T. koningii, H. virens/T. virens, T. tomentosum, H. semiorbis, H. viridescens/T. viridescens, H. atroviridis/T. atroviride, T. asperellum, H. koningiopsis/T. koningiopsis and Trichoderma sp. Vd2. Only one isolate represented a new, undescribed species belonging to the Harzianum,Catoptron Clade. Internal transcribed spacer sequence analysis revealed only one potentially endemic internal transcribed spacer 1 allele of T. hamatum. All other species exhibited genotypes that were already found in Eurasia or in other continents. Only few cases of correlation of species occurrence with abiotic factors were recorded. The data suggest a strong reduction of native Hypocrea/Trichoderma diversity, which was replaced by extensive invasion of species from Eurasia, Africa and the Pacific Basin. [source]

Population dynamics of the ectomycorrhizal fungal species Tricholoma populinum and Tricholoma scalpturatum associated with black poplar under differing environmental conditions

ENVIRONMENTAL MICROBIOLOGY, Issue 5 2006
Hervé Gryta
Summary Fungi combine sexual reproduction and clonal propagation. The balance between these two reproductive modes affects establishment dynamics, and ultimately the evolutionary potential of populations. The pattern of colonization was studied in two species of ectomycorrhizal fungi: Tricholoma populinum and Tricholoma scalpturatum. The former is considered to be a host specialist whereas T. scalpturatum is a generalist taxon. Fruit bodies of both basidiomycete species were mapped and collected over several years from a black poplar (Populus nigra) stand, at two different sites. Multilocus genotypes (= genets) were identified based on the analysis of random amplified polymorphic DNA (RAPD) patterns, inter-simple sequence repeat (ISSR) patterns and restriction fragment length polymorphisms (RFLPs) in the ribosomal DNA intergenic spacer (rDNA IGS). The genetic analyses revealed differences in local population dynamics between the two species. Tricholoma scalpturatum tended to capture new space through sexual spores whereas T. populinum did this by clonal growth, suggesting trade-offs in allocation of resources at the genet level. Genet numbers and sizes strongly differ between the two study sites, perhaps as a result of abiotic disturbance on mycelial establishment and genet behaviour. [source]

Ecotype diversity in the marine picoeukaryote Ostreococcus (Chlorophyta, Prasinophyceae)

ENVIRONMENTAL MICROBIOLOGY, Issue 6 2005
Francisco Rodríguez
Summary The importance of the cyanobacteria Prochlorococcus and Synechococcus in marine ecosystems in terms of abundance and primary production can be partially explained by ecotypic differentiation. Despite the dominance of eukaryotes within photosynthetic picoplankton in many areas a similar differentiation has never been evidenced for these organisms. Here we report distinct genetic [rDNA 18S and internal transcribed spacer (ITS) sequencing], karyotypic (pulsed-field gel electrophoresis), phenotypic (pigment composition) and physiological (light-limited growth rates) traits in 12 Ostreococcus strains (Prasinophyceae) isolated from various marine environments and depths, which suggest that the concept of ecotype could also be valid for eukaryotes. Internal transcribed spacer phylogeny grouped together four deep strains isolated between 90 m and 120 m depth from different geographical origins. Three deep strains displayed larger chromosomal bands, different chromosome hybridization patterns, and an additional chlorophyll (chl) c -like pigment. Furthermore, growth rates of deep strains show severe photo-inhibition at high light intensities, while surface strains do not grow at the lowest light intensities. These features strongly suggest distinct adaptation to environmental conditions encountered at surface and the bottom of the oceanic euphotic zone, reminiscent of that described in prokaryotes. [source]

Application de la variabilité génétique de l'ADNr chez Monilinia laxa, Monilinia fructigena et Monilinia fructicolaà l'identification des espèces par PCR,

EPPO BULLETIN, Issue 3-4 2000
R. Ioos
Monilinia laxa, Monilinia fructigena et Monilinia fructicola sont des agents de pourriture de fruit et de chancre sur rameau des arbres fruitiers. La région des ITS (internal transcribed spacer) située entre les gènes codant pour les sous-unités ribosomiques 18S et 28S de quatre isolats de M. fructigena et quatre isolats de M. fructigena collectés en France a été amplifiée par PCR et séquencée. L'alignement multiple de ces séquences d'ITS et leur comparaison avec les séquences d'ITS de Monilinia spp. publiées a révélé une très faible variabilité intraspécifique. Par contre, un faible polymorphisme interspécifique a été localisé au niveau de deux régions, respectivement dans l'ITS1 et l'ITS2. Ces deux régions ont été utilisées pour définir des couples d'oligonucléotides espèce-spécifiques. Ces couples d'amorces ont permis d'amplifier par PCR un fragment de 356 pb pour chacune des trois espèces. La spécificité des trois couples d'amorces a été vérifiée avec succès sur une collection de 17 isolats de M. laxa, 18 isolats de M. fructigena et 6 isolats de M. fructicola isolés de différents hôtes. En utilisant des conditions stringentes lors de la PCR, aucune réaction croisée n'a été observée avec les isolats testés. La spécificité du test a été d'autre part vérifiée avec l'ADN total extrait de différentes espèces de champignons, soit phylogénétiquement proche du genre Monilinia soit fréquemment isolées de fruits malades. L'utilisation de cette technique permet d'identifier avec fiabilité un isolaat indéterminé en une seule amplification, en le testant simultanément avec chacun des trois couples d'amorces. De plus, la détection et l'identification des espèces de Monilinia peuvent être réalisés directement à partir de fruits présentant des symptômes. Cette méthode simple et rapide pourrait être particulièrement utile pour détecter M. fructicola qui est un organisme de quarantaine pour l'Europe. [source]

Synthesis, Protonation and CuII Complexes of Two Novel Isomeric Pentaazacyclophane Ligands: Potentiometric, DFT, Kinetic and AMP Recognition Studies

EUROPEAN JOURNAL OF INORGANIC CHEMISTRY, Issue 1 2009
Andrés G. Algarra
Abstract The synthesis and coordination chemistry of two novel ligands, 2,6,9,12,16-pentaaza[17]metacyclophane (L1) and 2,6,9,12,16-pentaaza[17]paracyclophane (L2), is described. Potentiometric studies indicate that L1 and L2 form a variety of mononuclear complexes the stability constants of which reveal a change in the denticity of the ligand when moving from L1 to L2, a behaviour that can be qualitatively explained by the inability of the paracyclophanes to simultaneously use both benzylic nitrogen atoms for coordination to a single metal centre. In contrast, the formation of dinuclear hydroxylated complexes is more favoured for the paraL2 ligand. DFT calculations have been carried out to compare the geometries and relative energies of isomeric forms of the [CuL]2+ complexes of L1 and L2 in which the cyclophane acts either as tri- or tetradentate. The results indicate that the energy cost associated with a change in the coordination mode of the cyclophane from tri- to tetradentate is moderate for both ligands so that the actual coordination mode can be determined not only by the characteristics of the first coordination sphere but also by the specific interactions with additional nearby water molecules. The kinetics of the acid promoted decomposition of the mono- and dinuclear CuII complexes of both cyclophanes have also been studied. For both ligands, dinuclear complexes convert rapidly to mononuclear species upon addition of excess acid, the release of the first metal ion occurring within the mixing time of the stopped-flow instrument. Decomposition of the mononuclear [CuL2]2+ and [CuHL2]3+ species occurs with the same kinetics, thus showing that protonation of [CuL2]2+ occurs at an uncoordinated amine group. In contrast, the [CuL1]2+ and [CuHL1]3+ species show different decomposition kinetics indicating the existence of significant structural reorganisation upon protonation of the [CuL1]2+ species. The interaction of AMP with the protonated forms of the cyclophanes and the formation of mixed complexes in the systems Cu,L1 -AMP, Cu,L2 -AMP, and Cu,L3 -AMP, where L3 is the related pyridinophane containing the same polyamine chain and 2,6-dimethylpyridine as a spacer, is also reported. (© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2009) [source]

Study of the Effect of the Phosphane Bridging Chain Nature on the Structural and Photophysical Properties of a Series of Gold(I) Ethynylpyridine Complexes

EUROPEAN JOURNAL OF INORGANIC CHEMISTRY, Issue 18 2008
Montserrat Ferrer
Abstract Alkynyl AuI complexes of the type [Au(C,CC5H4N)(PPh3)] (1) [Au2(C,CC5H4N)2 (diphosphane)] [diphosphane = bis(diphenylphosphanyl)methane (2), bis(diphenylphosphanyl)isopropane] (3), bis(diphenylphosphanyl)acetylene (4), 1,2-bis(diphenylphosphanyl)ethane (5), 1,3-bis(diphenylphosphanyl)propane (6), 1,4-bis(diphenylphosphanyl)butane (7), 1,1,-bis(diphenylphosphanyl)ferrocene (8) and [Au3(C,CC5H4N)3(triphos)] [triphos = 1,1,1-tris(diphenylphosphanylmethyl)ethane] (9) were prepared by reaction of [Au(C,CC5H4N)]n with the suitable phosphane. Determination of the X-ray crystal structures of several compounds bearing different carbon backbones between the phosphorus atoms reveals the influence of the nature of the phosphane spacer on the establishment of intra and/or intermolecular gold,gold interactions. The absorption and emission properties of the complexes were analysed by taking into account the presence or absence of intermetallic interactions. Although UV/Vis spectra show differences for compounds with intramolecular Au,Au contacts, a conclusive trend was not observed in the emission behaviour. (© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2008) [source]

Structure Variation and Luminescence Properties of Lanthanide Complexes Incorporating a Naphthalene-Derived Chromophore Featuring Salicylamide Pendant Arms

EUROPEAN JOURNAL OF INORGANIC CHEMISTRY, Issue 11 2008
Xue-Qin Song
Abstract A new potentially bridging ligand containing two salicylamide pendant arms separated by a 2,3-dimethoxynaphthalene spacer has been prepared and its coordination chemistry with LnIII ions has been investigated. An analysis of the presented crystal structures indicates that the diversity of these supramolecular structures is mainly dictated by the nature of the metal ions. These compounds represent good examples of tuning crystal structures arising from the flexibility of the ligands and the Ln contraction effect. Luminescence studies showed that the introduction of the methoxyl substituents on the naphthalene backbone lowers the triplet energy and considerably changes the luminescent behaviors of the EuIII and TbIII complexes, which is very different from the literature data on similar compounds. In the emission spectra of the Tb complex the ligand fluorescence remains relatively important because of the back-energy transfer from the TbIII ion to the ligand, which to the best of our knowledge, may be the first example of salicylamide lanthanide complexes. (© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2008) [source]

Synthesis of Polyamines from Ethylenediamine and Their Platinum(II) Complexes, Potential Antitumor Agents

EUROPEAN JOURNAL OF INORGANIC CHEMISTRY, Issue 9 2006
Mara Rubia Costa Couri
Abstract This work describes the synthesis and characterization of five new amine ligands and also the preparation and characterization of their respective platinum(II) complexes by reaction with K2PtCl4 in water. These ligands were obtained by treatment of different halides or epoxides with ethylenediamine. Cytotoxic activity and cellular accumulation of three complexes were investigated in a human small-cell lung carcinoma cell line and its cisplatin resistant subline. The introduction of a spacer (cycle) between the two platinum atoms leads to a significant decrease in cytotoxic activity. At equitoxic doses, the intracellular platinum concentrations found for compounds 12 and 15 were significantly higher than those found for the reference compounds, cisplatin, carboplatin, or compound 9. This fact suggests that the formation of adducts between compounds 12 and 15 and the putative pharmacological target, DNA, is less favored. If these compounds bind more slowly to DNA, interaction with other intracellular ligands such as sulfur-containing molecules will become relevant and it may be the reason for the elevated intracellular platinum concentrations. (© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2006) [source]

Non-Covalent Aggregation of Discrete Metallo-Supramolecular Helicates into Higher Assemblies by Aromatic Pathways: Structural and Chemical Studies of New Aniline-Based Neutral Metal(II) Dihelicates

EUROPEAN JOURNAL OF INORGANIC CHEMISTRY, Issue 17 2005
Miguel Vázquez
Abstract Neutral manganese(II), iron(II), cobalt(II), nickel(II), zinc(II) and cadmium(II) complexes with an N -tosyl-substituted N4 -donor Schiff base containing a 4,4'-methylenedianiline residue as spacer [H2La: N,N' -bis(2-tosylaminobenzylidene)-4,4'-methylenedianiline], and the zinc(II) complex with an analogous ligand [H2Lb: N,N' -bis(2-tosylaminobenzylidene)-4,4'-oxodianiline] have been prepared by an electrochemical procedure. FAB and ESI mass spectra of the complexes show peaks due to species corresponding to a general formula [M2(La,b)2 + H]+, thereby suggesting their dinuclear nature. A detailed study of the crystal packing in the unit cell of the zinc(II) complex with H2La shows that the helicates aggregate to form discrete prismatic moieties containing three molecules held together by ,,, and ,,, interactions. Moreover, the ZnII neutral dihelicate with H2Lb forms a 3D network in the solid state due to intermolecular ,-stacking interactions. 1H NMR studies of the diamagnetic compounds reported herein have been performed. Finally, the ligand H2La and its ZnII and CdII complexes have been studied by spectrophotometric and spectrofluorimetric techniques in order to get a better understanding of the formation mechanisms of the complexes and of the nature of their fluorescence emission. Emission studies show that the ZnII and CdII dihelicates with H2La display a green fluorescence in acetonitrile solution (, = 473 nm, , = 0.03 and , = 476 nm, , = 0.01, respectively). (© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2005) [source]

Mono- and Dinuclear CuII and ZnII Complexes of Cyclen-Based Bis(macrocycles) Containing Two Aminoalkyl Pendant Arms of Different Lengths

EUROPEAN JOURNAL OF INORGANIC CHEMISTRY, Issue 11 2005
Carmen Anda
Abstract The basicity and coordination properties towards CuII and ZnII of the bis(macrocycles) L1, L2 and L3 have been investigated by means of potentiometric, 1H NMR and UV/Vis spectroscopic titrations in aqueous solutions. The synthesis of L1 and L3 is also described. The three ligands are composed of two [12]aneN4 units separated by a p- phenylene spacer and differ in the length of the aminoalkyl pendant arms linked to each macrocyclic unit. L1,L3 form mono- and dinuclear complexes in aqueous solutions; in the dinuclear species each metal ion is coordinated by one of the two identical [12]aneN4 ligand moieties, as shown by the crystal structures of the complexes [Cu2L1]Cl4·8H2O, [Zn2L2](ClO4)4 and [Zn2L3](ClO4)4·H2O. In all structures the metal ion is pentacoordinate, and is bound to the four nitrogen donors of the cyclic unit and to the amine group of the side arm. The stability of both the [ML]2+ and [M2L]4+ complexes in aqueous solution decreases in the order L1 > L2 > L3. At the same time, both the [Cu2L]4+ and [Zn2L]4+ complexes show a different ability in proton binding among the three ligands, with the [M2L1]4+ complexes displaying the highest basicity. These results are explained in terms of the decreasing number of nitrogen donors involved in CuII or ZnII binding on passing from L1 to L3; in other words, while in the L1 dinuclear complexes each metal ion is coordinated to the four amine groups of a [12]aneN4 moiety and to the amine group of the side arm, in the L3 ones the metal cations are bound only to the four donor atoms of a cyclic moiety, the aminobutyl group not being coordinated. (© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2005) [source]