Quantification of the biocontrol agent Pseudomonas fluorescens Pf153 in soil using a quantitative competitive PCR assay unaffected by variability in cell lysis- and DNA-extraction efficiency     

Davide Gobbin  Fabio Rezzonico  Cesare Gessler 《Soil biology & biochemistry》2007,39(7):1609-1619

Although often neglected, variability in cell lysis efficiency and DNA extraction yield represents the major hurdles of any polymerase chain reaction (PCR)-based quantification protocol in soil and other natural environments. In this study we developed a technique that minimizes the effects of these constraints, providing at the same time a reliable internal control to distinguish between PCR-inhibition and negative results. We used Pseudomonas fluorescens Pf153, a root-colonizing bacterium that shows biocontrol activity against tobacco and cucumber black root rot, as the target organism for PCR quantification. Prior to DNA extraction, the genetically engineered, cognate reference strain P. fluorescens CHA0/c2 was inoculated in a reference soil. CHA0/c2 in the reference soil and Pf153 in the soil sample were lysed in parallel and afterward the lysates were mixed in known proportions. CHA0/c2 carries the plasmid pME6031-cmp2 that contains an allelic variant (competitor) of the Pf153 specific sequence Pf153_2. In a quantitative competitive PCR (QC-PCR) assay the competitor allows the quantification of the target strain down to 0.66 Pf153 CFU/mg soil. Processing the reference strain in the same way as Pf153 enables the exact quantification of the target strain in biocontrol assays performed in natural soil, overcoming differences in DNA extraction efficiency and PCR amplification from different soil environments. This technique is easily adaptable to other Pseudomonas strains simply by replacing the competitor used here with one derived from a SCAR-marker which is specific for the strain of choice.  相似文献   

A map of the interactome network of the metazoan C. elegans   总被引：1，自引：0，他引：1  

Li S  Armstrong CM  Bertin N  Ge H  Milstein S  Boxem M  Vidalain PO  Han JD  Chesneau A  Hao T  Goldberg DS  Li N  Martinez M  Rual JF  Lamesch P  Xu L  Tewari M  Wong SL  Zhang LV  Berriz GF  Jacotot L  Vaglio P  Reboul J  Hirozane-Kishikawa T  Li Q  Gabel HW  Elewa A  Baumgartner B  Rose DJ  Yu H  Bosak S  Sequerra R  Fraser A  Mango SE  Saxton WM  Strome S  Van Den Heuvel S  Piano F  Vandenhaute J  Sardet C  Gerstein M  Doucette-Stamm L  Gunsalus KC  Harper JW  Cusick ME  Roth FP  Hill DE  Vidal M 《Science (New York, N.Y.)》2004,303(5657):540-543

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Vacuum Squeezing of Solids: Macroscopic Quantum States Driven by Light Pulses     

GA Garrett  AG Rojo  AK Sood  JF Whitaker  R Merlin 《Science (New York, N.Y.)》1997,275(5306):1638-1640

Femtosecond laser pulses and coherent two-phonon Raman scattering were used to excite KTaO3 into a squeezed state, nearly periodic in time, in which the variance of the atomic displacements dips below the standard quantum limit for half of a cycle. This nonclassical state involves a continuum of transverse acoustic modes that leads to oscillations in the refractive index associated with the frequency of a van Hove singularity in the phonon density of states.  相似文献   

Pre-unfolding resonant oscillations of single green fluorescent protein molecules     

Baldini G  Cannone F  Chirico G 《Science (New York, N.Y.)》2005,309(5737):1096-1100

Fluorescence spectroscopy of a green fluorescent protein mutant at single-molecule resolution has revealed a remarkable oscillatory behavior that can also be driven by applied fields. We show that immediately before unfolding, several periodic oscillations among the chemical substates of the protein chromophore occur. We also show that applied alternating electric or acoustic fields, when tuned to the protein characteristic frequencies, give rise to strong resonance effects.  相似文献   

Spatio-temporal impacts of roads on the persistence of populations: analytic and numerical approaches     

Luís?Borda-de-águaEmail author  Laetitia?Navarro  Catarina?Gavinhos  Henrique?M.?Pereira 《Landscape Ecology》2011,26(2):253-265

Roads can have drastic impacts on wildlife populations. Although there is wide recognition of the negative impacts caused by roads and a wealth of practical studies, there is a lack of theoretical work that can be used to predict the impact of road networks or to implement mitigation measures. Here, using Skellam’s diffusion model, we develop analytic and numerical approaches to analyze the impact of road networks on the survival of populations. Our models show that the viability of a population is determined not only by road density but also by the size and shape of patches. Accordingly, we studied the minimum size of a patch to sustain a population with given diffusion and growth parameters. We provide simple formulas to estimate the minimum patch size, and illustrate the importance of shape with square and rectangular patches. Our models also allow the estimation of time to extinction after road construction for a population in a patch smaller than that of the minimum size. Finally, using numerical computations we illustrate how the spatial arrangement of fences strongly affects both the equilibrium density and the spatial distribution of populations, and that not all fence layouts are equally effective. We anticipate that our methods provide a tool to assess the impact of geometrical features of road networks on wildlife and that they can be used to design mitigation measures to prevent the decline and extinction of populations in an anthropogenically disturbed landscape.  相似文献   

Transient receptor proteins illuminated: Current views on TRPs and disease     

Piper L. Nelson  Andreas Beck  Henrique Cheng 《Veterinary journal (London, England : 1997)》2011,187(2):153-164

The transient receptor potential proteins (TRPs) make up a very important family of ion channels responsible for a wide array of cellular functions. Originally identified in the visual system of Drosophila melanogaster, these channels are ubiquitously distributed throughout the mammalian system. The TRP family is divided into seven subfamilies in two groups: the first group comprises TRPC (canonical), TRPV (vanilloid), TRPM (melastatin), TRPN (Drosophila NOMPC) and TRPA (ankyrin). The second group contains TRPML (mucolipin) and TRPP (polycystin).The biophysical characterization of TRPs has revealed significantly different activation mechanisms and selectivity between channels. Functional studies have demonstrated that TRPs are necessary for a number of physiological processes, including sensation (such as taste, smell and temperature), hormone secretion and development. TRPs mediate these effects mainly by controlling the intracellular Ca²⁺ concentration, which acts as a second messenger. Recent research has linked TRPs to different diseases. This review considers the impact of TRPs on cell physiology and the abnormalities observed with channel dysfunction.  相似文献   

Penicilliosis in an African grey parrot (Psittacus erithacus)     

Lanteri G  Sfacteria A  Macri D  Reale S  Marino F 《Journal of zoo and wildlife medicine》2011,42(2):309-312

Penicillium mycosis, or penicilliosis, is rare in animals. This report describes the clinical signs and pathological, immunohistochemical, and biomolecular findings in a case of avian penicilliosis in a Congo African grey parrot. On gross necropsy, pyogranulomatous changes were identified in the lung, liver, and kidney. Histopathology demonstrated periodic acid Schiff-(PAS) and Grocott-positive hyphae in these tissues. Immunohistochemistry confirmed the genus of the fungus and polymerase chain reaction (PCR) confirmed a high homology with Penicillium chrysogenum.  相似文献   

Phosphate Fertilizers for Sugarcane Used at Pre-Planting (Phosphorus Fertilizer Application)     

Robson Thiago Xavier de Sousa  Gaspar Henrique Korndörfer  Rogério Augusto Brem Soares  Patrícia Rezende Fontoura 《Journal of plant nutrition》2015,38(9):1444-1455

Phosphate applications are still rare in sugarcane cultivation and can be done with phosphorus fertilizers of residual over. This study aims to evaluate the agronomic efficiency of phosphate fertilization before sugarcane planting and its effect on sugarcane yield. The study was carried out over three crop cycles at the Jalles Machado sugar-mill in Goianésia, GO, Brazil. The treatments consisted of five different phosphorus sources (soluble and insoluble) applied at a rate of 300 kg ha^?1 phosphorus pentoxide (P₂O₅). The phosphorus fertilizers used were: triple superphosphate, mono-ammonium phosphate (MAP), Arad rock phosphate, Itafós rock phosphate, and magnesium term phosphate. The effects of these fertilizers were evaluated by plant height (ground to Top Visible Dewlap; TVD), leaf phosphorus content, agronomic efficiency, and sugarcane yield from cane-plants, first ratoon, and second ratoon. Magnesium term phosphate and triple superphosphate resulted in greater plant-cane height. Leaf phosphorus concentrations were highest with applications of MAP, magnesium term phosphate, and triple superphosphate. Phosphate applications did not affect sugarcane plant yield, but did increase ratoon yield. In general, the residual effect of insoluble phosphate increased over the years. The agronomic efficiency (AE) of phosphate was (in descending order): triple superphosphate (100%), term phosphate (89%), MAP (80%), Itafós rock phosphate (67%), and Arad rock phosphate (60%).  相似文献   

On the chemical composition and nutritional value of pleurotus taxa growing on umbelliferous plants (apiaceae)     

La Guardia M  Venturella G  Venturella F 《Journal of agricultural and food chemistry》2005,53(15):5997-6002

Unpublished data on the chemical composition and nutritional value of Pleurotus mushrooms, growing on Umbelliferous plants (Apiaceae), are here reported. Cultivated basidiomata of four different Pleurotus taxa were analyzed in order to evaluate the composition in lipids, sugars, nitrogen, water, vitamins, ashes, and energetic values. The results showed that Pleurotus mushrooms are suitable in every type of diet thanks to their low caloric content, gastronomic value, vitamins, and mineral salt contents. The presence of a high content of vitamin B(12) and riboflavin in Pleurotus nebrodensis is noteworthy.  相似文献   

Methoxylated xanthones in the quality control of small centaury (Centaurium erythraea) flowering tops.     

Patrícia Valent?o  Paula B Andrade  Eurico Silva  Ana Vicente  Henrique Santos  M Lourdes Bastos  Rosa M Seabra 《Journal of agricultural and food chemistry》2002,50(3):460-463

In the course of a phytochemical study of the bitter tonic plant, small centaury (Centaurium erythraea), six methoxylated xanthones (1,5-hydroxy-3-methoxyxanthone, 1-hydroxy-3,5,6-trimethoxyxanthone, 1-hydroxy-3,5,6,7-tetramethoxyxanthone, 1-hydroxy-3,5,6,7,8-pentamethoxyxanthone, 1-hydroxy-3,7,8-trimethoxyxanthone and 1,8-dihydroxy-3,5,6,7-tetramethoxyxanthone) were isolated and identified by spectroscopic means (nuclear magnetic resonance, mass spectroscopy, and UV). Subsequently, a high-performance liquid chromatography/diode array detection method was developed for the determination of these and other methoxylated xanthones occurring in the chloroform extract of small centaury aerial parts. The methodology developed was applied to twelve samples, and in all of them, nine xanthones were identified and quantified. This methodology can be considered complimentary to the one proposed by the European Pharmacopoeia.  相似文献