Assessment of the loose smut fungi (Ustilago nuda and U. tritici) in tissues of barley and wheat by fluorescence microscopy and real-time PCR     

Jan Wunderle  Andreas Leclerque  Ulrich Schaffrath  Alan Slusarenko  Eckhard Koch 《European journal of plant pathology / European Foundation for Plant Pathology》2012,133(4):865-875

Loose smut fungi of barley and wheat (Ustilago nuda and U. tritici, respectively) colonize the plant without causing obvious disease symptoms before heading. The availability of diagnostic methods to detect and follow the growth of these pathogens in the plant would therefore be highly advantageous for both resistance breeding and the development of effective seed treatments. Using seed lots of barley and wheat highly infected with loose smut, we studied the early establishment of the loose smut pathogens in the plant by fluorescence microscopy. In hand-cut sections stained with the fluorochrome Blankophor?, fungal hyphae were observed to invade the shoot apical meristem and leaf primordia during the first days after the onset of germination. At the first node stage the ear and leaf primordia were generally extensively colonized. Hyphae of U. nuda were also regularly observed in high density in the nodes. A protocol was developed for the specific amplification of U. nuda and U. tritici DNA extracted from infected plant tissue. PCR screening of U nuda in seedlings from infected and healthy seed lots was compared to ELISA, microscopy and ultimately head infection of mature plants derived from tillers of the tested seedlings. The results indicated that a prediction of loose smut infection by real-time PCR is possible at the second leaf stage, and that the assay is equally suited for use with spring and winter varieties of barley and wheat.  相似文献   

Iron catalysts for selective anti-Markovnikov alkene hydrosilylation using tertiary silanes     

Tondreau AM  Atienza CC  Weller KJ  Nye SA  Lewis KM  Delis JG  Chirik PJ 《Science (New York, N.Y.)》2012,335(6068):567-570

Alkene hydrosilylation, the addition of a silicon hydride (Si-H) across a carbon-carbon double bond, is one of the largest-scale industrial applications of homogeneous catalysis and is used in the commercial production of numerous consumer goods. For decades, precious metals, principally compounds of platinum and rhodium, have been used as catalysts for this reaction class. Despite their widespread application, limitations such as high and volatile catalyst costs and competing side reactions have persisted. Here, we report that well-characterized molecular iron coordination compounds promote the selective anti-Markovnikov addition of sterically hindered, tertiary silanes to alkenes under mild conditions. These Earth-abundant base-metal catalysts, coordinated by optimized bis(imino)pyridine ligands, show promise for industrial application.  相似文献   

Biogenic potassium salt particles as seeds for secondary organic aerosol in the Amazon     

C Pöhlker  KT Wiedemann  B Sinha  M Shiraiwa  SS Gunthe  M Smith  H Su  P Artaxo  Q Chen  Y Cheng  W Elbert  MK Gilles  AL Kilcoyne  RC Moffet  M Weigand  ST Martin  U Pöschl  MO Andreae 《Science (New York, N.Y.)》2012,337(6098):1075-1078

The fine particles serving as cloud condensation nuclei in pristine Amazonian rainforest air consist mostly of secondary organic aerosol. Their origin is enigmatic, however, because new particle formation in the atmosphere is not observed. Here, we show that the growth of organic aerosol particles can be initiated by potassium-salt-rich particles emitted by biota in the rainforest. These particles act as seeds for the condensation of low- or semi-volatile organic compounds from the atmospheric gas phase or multiphase oxidation of isoprene and terpenes. Our findings suggest that the primary emission of biogenic salt particles directly influences the number concentration of cloud condensation nuclei and affects the microphysics of cloud formation and precipitation over the rainforest.  相似文献   

Dislocation damping and anisotropic seismic wave attenuation in Earth's upper mantle     

Farla RJ  Jackson I  Fitz Gerald JD  Faul UH  Zimmerman ME 《Science (New York, N.Y.)》2012,336(6079):332-335

Crystal defects form during tectonic deformation and are reactivated by the shear stress associated with passing seismic waves. Although these defects, known as dislocations, potentially contribute to the attenuation of seismic waves in Earth's upper mantle, evidence for dislocation damping from laboratory studies has been circumstantial. We experimentally determined the shear modulus and associated strain-energy dissipation in pre-deformed synthetic olivine aggregates under high pressures and temperatures. Enhanced high-temperature background dissipation occurred in specimens pre-deformed by dislocation creep in either compression or torsion, the enhancement being greater for prior deformation in torsion. These observations suggest the possibility of anisotropic attenuation in relatively coarse-grained rocks where olivine is or was deformed at relatively high stress by dislocation creep in Earth's upper mantle.  相似文献   

Effect of conventional and minimum tillage on physical and biochemical stabilization of soil organic matter   总被引：2，自引：0，他引：2  

Anna Jacobs  Mirjam Helfrich  Susan Hanisch  Ulrich Quendt  Rolf Rauber  Bernard Ludwig 《Biology and Fertility of Soils》2010,46(7):671-680

The objectives were to investigate (1) to which extent water-stable macro- and microaggregates sequester organic matter (OM) in a minimum tillage (MT) system compared to a conventional tillage (CT) system and (2) if the content of biochemically stabilized OM differs between both tillage systems, and (3) to study the temporal dynamics of the distribution of aggregate size classes and of storage of OM within aggregates in the field. Surface soils (0–5 cm) and subsoils (10–20 cm) were sampled after fallow (March 2007) and directly after tillage (November 2007) from a long-term experimental field near Göttingen, Germany. Macroaggregates (>0.25 mm) were in general less abundant after fallow than directly after tillage. In March, only 21% (CT) and 45% (MT) of C_org was stored within macroaggregates in the surface soil, whereas in November, the percentages increased to 58% and 73%, respectively. CT and MT soils of both depths were incubated as bulk soil (CT_bulk, MT_bulk) and with macroaggregates disrupted (<0.25 mm) (CT_md, MT_md) for 28 days at 22°C and water content of 50% of the maximum water holding capacity. For the MT_bulk and MT_md surface soils, C mineralization was significantly higher compared to the CT soils. Incubation of md soils did not generally result in a significantly higher C mineralization compared to the respective bulk soils, except for the MT_md subsoil. Acid hydrolysis showed that the proportion of biochemically stabilized, nonhydrolysable, C_org to total C_org was lower in the MT than in the CT soils. Overall, the data indicate that the effect of physical stabilization of OM stored in the macroaggregates may not be a mechanism protecting very labile C with a turnover time of weeks, but that longer preservation likely occurs after macroaggregate transformation into microaggregates, and the surplus of OM found in the surface soil of MT does not only depend on the biochemically stabilized OM. Finally, our data suggest that the temporal variability of distribution of aggregate size classes in the field is large, but spatial and operator variability also contributed to the observed differences.  相似文献   

BODIUM—A systemic approach to model the dynamics of soil functions     

Sara König  Ulrich Weller  Bibiana Betancur-Corredor  Birgit Lang  Thomas Reitz  Martin Wiesmeier  Ute Wollschläger  Hans-Jörg Vogel 《European Journal of Soil Science》2023,74(5):e13411

The increasing demand for biomass for food, animal feed, fibre and bioenergy requires optimization of soil productivity, while at the same time, protecting other soil functions such as nutrient cycling and buffering, carbon storage, habitat for biological activity and water filter and storage. Therefore, one of the main challenges for sustainable agriculture is to produce high yields while maintaining all the other soil functions. Mechanistic simulation models are an essential tool to fully understand and predict the complex interactions between physical, biological and chemical processes of soils that generate those functions. We developed a soil model to simulate the impact of various agricultural management options and climate change on soil functions by integrating the relevant processes mechanistically and in a systemic way. As a special feature, we include the dynamics of soil structure induced by tillage and biological activity, which is especially relevant in arable soils. The model operates on a 1D soil profile consisting of a number of discrete layers with dynamic thickness. We demonstrate the model performance by simulating crop growth, root growth, nutrient and water uptake, nitrogen cycling, soil organic matter turnover, microbial activity, water distribution and soil structure dynamics in a long-term field experiment including different crops and different types and levels of fertilization. The model is able to capture essential features that are measured regularly including crop yield, soil organic carbon, and soil nitrogen. In this way, the plausibility of the implemented processes and their interactions is confirmed. Furthermore, we present the results of explorative simulations comparing scenarios with and without tillage events to analyse the effect of soil structure on soil functions. Since the model is process-based, we are confident that the model can also be used to predict quantities that have not been measured or to estimate the effect of management measures and climate states not yet been observed. The model thus has the potential to predict the site-specific impact of management decisions on soil functions, which is of great importance for the development of a sustainable agriculture that is currently also on the agenda of the ‘Green Deal’ at the European level.  相似文献   

Is there a relationship between lateromedial foot imbalance and distal interphalangeal joint collateral ligament injuries?     

D. Reeve  T. Mair  J.J. Dixon  N. Bolas  R. Weller 《Journal of Equine Veterinary Science》2013

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Does hoof deformation differ between horses with collapsed heels and horses with non-collapsed heels?     

Peter DayDaniel Butts  Thilo PfauChris Pardoe  Renate Weller 《Journal of Equine Veterinary Science》2013

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How reliable is the use of hoof testers? The intra- and inter-operator repeatability of force application to different regions of the foot     

Jamie L. ArndtThilo Pfau  Peter DayChris Pardoe  David M. BoltRenate Weller 《Journal of Equine Veterinary Science》2013

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Hantavirus Infection among Wild Small Mammals in Vellore,South India     

S. Chandy  R. G. Ulrich  M. Schlegel  R. Petraityte  K. Sasnauskas  D. J. Prakash  V. Balraj  P. Abraham  G. Sridharan 《Zoonoses and public health》2013,60(5):336-340

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