Search results for " roots"
showing 10 items of 286 documents
Effect of natamycin on the enumeration, genetic structure and composition of bacterial community isolated from soils and soybean rhizosphere
2004
Natamycin is commonly used to control fungal growth on agar media used for bacterial enumeration or strain isolation. However, there is no conclusive report on the possible effect of this antibiotic on bacterial growth or on the diversity of the recovered soil bacteria. Therefore, the possible effects of natamycin on the numbers of bacteria isolated at 12 degrees C from three different soils and soybean rhizosphere soil were investigated using natamycin concentrations ranging from 0 to 200 mg l(-1). Our results demonstrate that natamycin concentrations, which inhibit the growth of fungi on the media, have a small but significant inhibitory effect on the number of bacterial colony forming un…
Identification of bacterial groups preferentially associated with mycorrhizal roots of Medicago truncatula
2007
ABSTRACT The genetic structures of bacterial communities associated with Medicago truncatula Gaertn. cv. Jemalong line J5 (Myc + Nod + ) and its symbiosis-defective mutants TRV48 (Myc + Nod − ) and TRV25 (Myc − Nod − ) were compared. Plants were cultivated in a fertile soil (Châteaurenard, France) and in soil from the Mediterranean basin showing a low fertility (Mas d'Imbert, France). Plant growth, root architecture, and the efficiency of root symbiosis of the three plant genotypes were characterized in the two soils. Structures of the bacterial communities were assessed by automated-ribosomal intergenic spacer analysis (A-RISA) fingerprinting from DNA extracted from the rhizosphere soil an…
Distribution and diversity of type III secretion system-like genes in saprophytic and phytopathogenic fluorescent pseudomonads
2004
Type three secretion systems (TTSSs) are protein translocation mechanisms associated with bacterial pathogenicity in host plants, and hypersensitive reactions in non-host plants. Distribution and diversity of TTSS-like genes within a collection of saprophytic and phytopathogenic fluorescent pseudomonads were characterized. This collection included 16 strains belonging to 13 pathogenic species, and 87 strains belonging to five saprophytic species isolated from plant rhizosphere and soil. Presence of conserved hypersensitive reaction/pathogenicity (hrp) genes (hrc RST) was assessed both by PCR using primers designed to amplify the corresponding sequence and by dot-blot hybridization using a P…
Relative Abundances of Proteobacterial Membrane-Bound and Periplasmic Nitrate Reductases in Selected Environments
2007
ABSTRACT Dissimilatory nitrate reduction is catalyzed by a membrane-bound and a periplasmic nitrate reductase. We set up a real-time PCR assay to quantify these two enzymes, using the narG and napA genes, encoding the catalytic subunits of the two types of nitrate reductases, as molecular markers. The narG and napA gene copy numbers in DNA extracted from 18 different environments showed high variations, with most numbers ranging from 2 × 10 2 to 6.8 × 10 4 copies per ng of DNA. This study provides evidence that, in soil samples, the number of proteobacteria carrying the napA gene is often as high as that of proteobacteria carrying the narG gene. The high correlation observed between narG an…
Tonoplast subcellular localization of maize cytochrome b5 reductases
2000
Plant cytochrome b 5 reductases (b 5 R) are assumed to be part of an ER-associated redox chain that oxidizes NADH to provide electrons via cytochrome b5 (cyt b 5 ) to ER-associated fatty acyl desaturase and related hydroxylases, as in mammalian cells. Here we report on cDNA cloning of a novel maize b 5 R, NFR II, strongly related to a previously cloned cDNA, NFR I (Bagnaresi et al., 1999, Biochem, J. 338, 499-5051. Maize b 5 R isoforms are produced by a small multi-gene family. The NFR cDNAs were shown to encode active b 5 Rs by heterologous expression in yeast. Both reductases, in addition to Fe 3+ -chelates, efficiently reduced Cu 2+ -chelates. Using a polyclonal antibody able to recogniz…
Phytochemical profile and bioactivity of traditional ayurvedic decoctions and hydro-alcoholic macerations of Boerhaavia diffusa L. and Curculigo orch…
2015
Decoctions (DECs) and hydro-alcoholic extracts (HEs) prepared from roots of Boerhaavia diffusa L. (Nyctaginaceae) and Curculigo orchioides Gaertn. (Hypoxidaceae) were phytochemically characterised by HPLC-DAD and profiled for their antioxidant, antigenotoxic and cytotoxic activities. B. diffusa DEC was rich in ferulic acid and vanillin, while the HE also contained boeravinone B and eupalitin. Both C. orchioides HE and DEC displayed the main occurrence of orcinol-β-d-glucoside and curculigoside A. Antioxidant activity was assayed through spectrophotometric DPPH, ABTS and β-carotene bleaching test, and using (HP)TLC bioautographic strategies. For both crude drugs, HE was the best performing p…
Nonlinear embeddings: Applications to analysis, fractals and polynomial root finding
2016
We introduce $\mathcal{B}_{\kappa}$-embeddings, nonlinear mathematical structures that connect, through smooth paths parameterized by $\kappa$, a finite or denumerable set of objects at $\kappa=0$ (e.g. numbers, functions, vectors, coefficients of a generating function...) to their ordinary sum at $\kappa \to \infty$. We show that $\mathcal{B}_{\kappa}$-embeddings can be used to design nonlinear irreversible processes through this connection. A number of examples of increasing complexity are worked out to illustrate the possibilities uncovered by this concept. These include not only smooth functions but also fractals on the real line and on the complex plane. As an application, we use $\mat…
On the Toeplitz algebras of right-angled and finite-type Artin groups
1999
The graph product of a family of groups lies somewhere between their direct and free products, with the graph determining which pairs of groups commute and which do not. We show that the graph product of quasi-lattice ordered groups is quasi-lattice ordered, and, when the underlying groups are amenable, that it satisfies Nica's amenability condition for quasi-lattice orders. As a consequence the Toeplitz algebras of these groups are universal for covariant isometric representations on Hilbert space, and their representations are faithful if the isometries satisfy a properness condition given by Laca and Raeburn. An application of this to right-angled Artin groups gives a uniqueness theorem …
Fungal genes related to calcium homeostasis and signalling are upregulated in symbiotic arbuscular mycorrhiza interactions
2012
Fluctuations in intracellular calcium levels generate signalling events and regulate different cellular processes. Whilst the implication of Ca2+ in plant responses during arbuscular mycorrhiza (AM) interactions is well documented, nothing is known about the regulation or role of this secondary messenger in the fungal symbiont. The spatio-temporal expression pattern of putatively Ca2+-related genes of Glomus intraradices BEG141 encoding five proteins involved in membrane transport and one nuclear protein kinase, was investigated during the AM symbiosis. Expression profiles related to successful colonization of host roots were observed in interactions of G. intraradices with roots of wild-ty…
Is the environmental performance of industrialized countries converging? A ‘SURE’ approach to testing for convergence
2008
In this paper, we test for convergence in the environmental performance of a sample of OECD countries, with data ranging from 1971 to 2002. First, we use Data Envelopment Analysis (DEA) to compute two environmental performance indicators (EPIs) in the production theory framework. Second, we propose the use of a sequential multivariate approach to test for convergence in environmental performance. These tests allow us to reconcile the time series literature with the cross-sectional dimension, which is basic when testing for convergence in regional blocs. The SURE technique is used, which allows for the existence of correlations across the series without imposing a common speed of mean revers…