Semi-selective culture medium for Curtobacterium flaccumfaciens pv. flaccumfaciens isolation from bean seeds

Curtobacterium wilt has become an important disease of beans in several localities in the country. Its causal agent, Curtobacterium flaccumfacciens pv. flaccumfaciens (Cff), survives and is disseminated through seeds. To date, few studies have been conducted with the objective of developing an effective and low-cost culture medium to isolate this bacterium from bean seeds, for health analysis purposes. Usually, the culture media employed for coryneform bacteria isolation contain specific carbon sources and antimicrobial products not available in the Brazilian market. A culture medium known as MSCFF was developed (peptone - 5 g, meat extract - 3 g, sucrose - 5 g, agar 15 g, skim milk powder* - 5 g. Congo red* - 0.05 g-, chlorothalonil* - 0.01 g, thiophanate methyl* - 0.01 g, nalidixic acid* - 0.01 g, nitrofurantoin* - 0.01 g. oxacillin* 0.001 g, sodium azide* - 0.001 g and distilled water q.s. 1L; *added after autoclaving the basal medium), which has the ability to inhibit growth of a large amount of saprophytic bacteria, but with low supressivity to Cff isolates. The MSCFF medium was highly effective for Cff isolation from naturally infected bean seeds and could be used for routine detection of this bacterium in bean seeds.

New selective acetylcholinesterase inhibitors designed from natural piperidine alkaloids

Five new piperidine alkaloids were designed from natural (-)-3-O-acetyl-spectaline and (-)-spectaline that were obtained from the flowers of Senna spectabilis (sin. Cassia spectabilis, Leguminosae). Two semi-synthetic analogues (7 and 9) inhibited rat brain acetylcholinesterase, showing IC50 of 7.32 and 15.1 mu M, and were 21 and 9.5 times less potent against rat brain butyrylcholinesterase, respectively. Compound 9 (1 mg/kg, ip) was fully efficacious in reverting scopolamine-induced amnesia in mice. The two active compounds (7 and 9) did not show overt toxic effects at the doses tested in vivo. (c) 2005 Elsevier Ltd. All rights reserved.

Curtobacterium flaccumfaciens pv. Flaccumfaciens detection in bean seeds using a semi-selective culture medium

The bacterial wilt caused by Curtobacterium flaccumfaciens pv. flaccumfaciens is currently considered one of the most important bacterial bean disease in Brazil. One of the most effective control methods against this disease is the use of healthy seeds. However, no methods are known that could be routinely used to detect this bacterium in bean seeds under Brazilian condition. The aim of this work was to evaluate qualitative and quantitative detection methods for Curtobacterium flaccumfaciens pv. flaccumfaciens in naturally-infected bean seeds, and the detection of this pathogen in thirty bean seed samples, by sowing onto a semi- selective culture medium the leachate obtained from soaked bean seeds. Both the qualitative and quantitative methods were effective for detecting the presence of the bacteria in the seeds samples analysed. The qualitative method proved more practical for rotine use; of the thirty bean seed samples analyzed by this method, fifty percent were infected with Curtobacterium flaccumfaciens pv. flaccumfaciens.

Limonoids showing selective toxicity to DNA repair-deficient yeast and other constituents of Trichilia emetica

Bioactivity-directed fractionation of the MeCOEt extract of Trichilia emetica (Meliaceae) resulted in the isolation of the limonoids nymania 1 (1), drageana 4 (3), trichilin A (4), rohituka 3 (5),and Tr-B (7) and the novel seco-A protolimonoid 8. of these, nymania 1 and Tr-B showed selective inhibitory activity toward DNA repair-deficient yeast mutants. The isolation, structure elucidation, C-13 NMR spectral assignments, and biological activities of:these compounds are reported.

Study of an organically modified clay: Selective adsorption of heavy metal ions and voltammetric determination of mercury(II)

In this work, a hydrophilic clay, Na-montmorillonite from Wyoming, USA, was rendered organophilic by exchanging the inorganic interlayer cations for hexaclecyltrimethylammonium ions (HDTA), with the formulae of [(CH3)(3)N(C16H33)](+) ion. Based on fact that organo-clay has high affinities for non-ionic organic molecules, 1,3,4-thiadiazole-2,5-dithiol was loaded oil the HDTA-montmorillonite surface, resulting in the 1,3,4-thiadiazole-2,5-dithiol-HDTA-montmorillonite complex (TDD-organo-clay).The following properties of TDD-organo-clay are discussed: selective adsorption of heavy metal ions measured by batch and chromatographic column techniques, and utilization as preconcentration agent in a chemically modified carbon paste electrode (CMCPE) for determination of mercury(II).The main point of this paper is the construction of a selective sensor, a carbon paste electrode modified with TDD-organo-clay, its properties and its application to the determination of mercury(II) ions, as this element belongs to the most toxic metals. The chemical selectivity of this functional group and the selectivity of voltammetry were combined for preconcentration and determination. (c) 2005 Elsevier B.V. All rights reserved.

A new method for the selective quantitation of cyanogenic glycosides by membrane introduction mass spectrometry

A new method is described for the rapid, sensitive, virtually interference-free, and selective quantitation of cyanogenic glycosides in aqueous extracts using membrane introduction mass spectrometry (MIMS). Selective monitoring, by either conventional MIMS or cryotrap-MIMS, not of HCN but of the co-released ketones (acetone and butan-2-one), when performed for both the crude cassava extracts and the linamarase-NaOH-hydrolyzed extracts, is found to offer an advantageous alternative to classic spectrophotometric methods based on HCN analysis for the selective quantitation of the two cyanogenic glycosides linamarin and lotaustralin expressed as both the free HCN content and the total cyanogenic potential (total HCN).

Determination of buprofezin, pyridaben, and tebufenpyrad residues by gas chromatography mass-selective detection in clementine citrus

A gas chromatography-mass-selective (GC-MS) detection method to determine buprofezin, pyridaben, and tebufenpyrad on the pulp, peel, and whole fruit of clementines is described. The extraction/partition procedure was performed in one step and no cleanup was necessary with the GC-MS in the SIM-mode pesticide determination. Recovery ranged from 75 to 124% with coefficients of variance ranging between 1 and 13%. The limit of determination was 0.01 mg/kg for all pesticides. The field trials showed a similar degradative behavior for all active ingredients (AI), with a great residue decrease during the first week and stability in the second. Just after treatment buprofezin and tebufenpyrad showed lower residues than the maximum residue limit (MRL) fixed in Italy, while pyridaben was below the MRL after a week.

2-Mercaptoimidazole covalently bonded to a silica gel surface for the selective separation of mercury(II) from an aqueous solution

Silica gel with a specific surface area of 365 m(2).g(-1) and an average pore diameter of 60 Angstrom was chemically modified with 2-mercaptoimidazole. The degree of functionalization of the covalently attached molecule, (drop SiO)(3)(CH2)(3) - MI, where MI is the 2-mercaptoimidazole bound to the silica surface by a propyl group, was 0.58 mmolg.(-1). In individual metal adsorption experiments from aqueous solutions by the batch procedure, the affinity order was Hg(II)much greater than Cd-II > Cu-II approximate to Zn-II approximate to Pb-II > Mn-II at solution pHs between 4 and 7. Due to the high affinity by the sulfur atom, Hg-II is strongly bound to the functional groups. When solution containing a mixture of Hg-II, Cd-II, Cu-II, Zn-II, Pb-II, and Mn-II ions was passed through a column packed with the adsorbent, Hg-II was the only one whose adsorption and elution was not affected by the presence of other ions.

Highly selective nickel ethylene oligomerization catalysts based on sterically hindered tris(pyrazolyl)borate ligands

The reaction of TlTp' (Tp' = HB(3-mesitylpyrazolyl)(3)(-) (Tp(Ms)), HB(3-mesitylpyrazolyl)(2)(5-mesitylpyrazolyl)(-) (Tp(Ms)*)) with NiCl(2).6H(2)O affords Tp(Ms)NiCl (1) and Tp(Ms)*NiCl (2) in good yield. The compound 2 undergoes an isomerization process to form [{Tp(Ms)**}NiCl](2) (3) (Tp(Ms)** = HB(5-mesitylpyrazolyl)(2)(3-mesitylpyrazolyl)(-)) in 68% yield. Treatment of the tris(pyrazolyl)-borate nickel compounds 1 and 2 with alkylaluminum cocatalysts such as methylalumoxane (MAO) and trimethylaluminum (TMA) in toluene generates active catalysts for ethylene oligomerization. The compound 1 shows turnover frequencies in the range of (2.2-43.1) x 10(3) h(-1). Oligomerization reaction conditions can be adjusted that lead to selectivities as high as 81% for butene-1.

Effects of selective logging on the mating system and pollen dispersal of Hymenaea courbaril L. (Leguminosae) in the Eastern Brazilian Amazon as revealed by microsatellite analysis

Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)

Feeding ecology of a selective folivore, the thin-spined porcupine (Chaetomys subspinosus) in the Atlantic forest

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Assessment of tropical forest degradation by selective logging and fire using Landsat imagery

Many studies have assessed the process of forest degradation in the Brazilian Amazon using remote sensing approaches to estimate the extent and impact by selective logging and forest fires on tropical rain forest. However, only a few have estimated the combined impacts of those anthropogenic activities. We conducted a detailed analysis of selective logging and forest fire impacts on natural forests in the southern Brazilian Amazon state of Mato Grosso, one of the key logging centers in the country. To achieve this goal a 13-year series of annual Landsat images (1992-2004) was used to test different remote sensing techniques for measuring the extent of selective logging and forest fires, and to estimate their impact and interaction with other land use types occurring in the study region. Forest canopy regeneration following these disturbances was also assessed. Field measurements and visual observations were conducted to validate remote sensing techniques. Our results indicated that the Modified Soil Adjusted Vegetation Index aerosol free (MSAVI(af)) is a reliable estimator of fractional coverage under both clear sky and under smoky conditions in this study region. During the period of analysis, selective logging was responsible for disturbing the largest proportion (31%) of natural forest in the study area, immediately followed by deforestation (29%). Altogether, forest disturbances by selective logging and forest fires affected approximately 40% of the study site area. Once disturbed by selective logging activities, forests became more susceptible to fire in the study site. However, our results showed that fires may also occur in undisturbed forests. This indicates that there are further factors that may increase forest fire susceptibility in the study area. Those factors need to be better understood. Although selective logging affected the largest amount of natural forest in the study period, 35% and 28% of the observed losses of forest canopy cover were due to forest fire and selective logging combined and to forest fire only, respectively. Moreover, forest areas degraded by selective logging and forest fire is an addition to outright deforestation estimates and has yet to be accounted for by land use and land cover change assessments in tropical regions. Assuming that this observed trend of land use and land cover conversion continues, we predict that there will be no undisturbed forests remaining by 2011 in this study site. Finally, we estimated that 70% of the total forest area disturbed by logging and fire had sufficiently recovered to become undetectable using satellite data in 2004. (C) 2010 Elsevier B.V. All rights reserved.