3,419 research outputs found
Essential role of the czc determinant for cadmium, cobalt and zinc resistance in Gluconacetobacter diazotrophicus PAl 5
The mechanisms of cadmium, cobalt and zinc resistance were characterized in the plant-growth-promoting bacterium Gluconacetobacter diazotrophicus PAl 5. The resistance level of the wild-type strain was evaluated through the establishment of minimum inhibitory concentrations (MIC) of the soluble compounds CdCl2·H2O, CoCl2·6H2O and ZnCl2. Gluconacetobacter diazotrophicus PAl 5 was resistant to high concentrations of Cd, Co and Zn, with MICs of 1.2, 20 and 20 mM, respectively. Screening of an insertion library from transposon EZ-Tn5<R6Kyori/KAN-2> in the presence of ZnO revealed that the mutant GDP30H3 was unable to grow in the presence of the compound. This mutant was also highly sensitive to CdCl2·H2O, CoCl2·6H2O and ZnCl2. Molecular characterization established that the mutation affected the czcA gene, which encodes a protein involved in metal efflux. In silico analysis showed that czcA is a component of the czcCBARS operon together with four other genes. This work provides evidence of the high tolerance of G. diazotrophicus PAl 5 to heavy metalsand that czc is a determinant for metal resistance in this bacterium. [Int Microbiol 2012; 15(2):69-78
Production and characterization of new fibrinolytic protease from Mucor subtillissimus UCP 1262 in solid-state fermentation
Fibrinolytic enzymes have received attention regarding their medicinal potential for thrombolytic
diseases, a leading cause of morbidity and mortality worldwide. Various natural enzymes purified
from animal, plant and microbial sources have been extensively studied. The aim of this work was
to produce fibrinolytic protease by solid state fermentation using agro industrial substrates. Rhizopus
arrhizus var. arrhizus UCP 1295 and Mucor subtillissimus UCP 1262 filamentous fungi species
isolated from soil of Caatinga-PE, Brasil, were used as producer microorganisms. Wheat bran
was shown to be the best substrate for the production of the enzyme and by using a 23 full factorial
design the main effects and interactions of the quantity of the substrate wheat bran, moisture and
temperature on the fibrinolytic enzyme production and protease were evaluated. The best results
for fibrinolytic and protease activities, 144.58 U/mL and 48.33 U/mL, respectively, were obtained
with Mucor subtillissimus UCP 1262 using as culture medium 3 g wheat bran, 50% moisture at a
temperature of 25ËšC for 72 hours. The optimum temperature for the produced enzyme was 45ËšC
and most of its original activity was retained after being subjected to 80ËšC for 120 min. The protease activity was enhanced by K+, Ca+ and Mn+; but with Cu+ there was an inhibition. The specificity
to chromogenic substrate and the inhibition by PMSF indicates that it is a chymotrypsin-like
serine protease. Presented results suggest that this enzyme produced by solid-state fermentation
is an interesting alternative as a candidate for thrombolytic therapy
SAMARAS OF AUSTROPLENCKIA POPULNEA (CELASTRACEAE): NEW CONSTITUENTS AND EFFECT OF EXTRACTS AND FRIEDELIN ON GERMINATION OF BIDENS PILOSA (ASTERACEAE)
Objective: Evaluation of the impact of extracts and constituents from samaras of Austroplenckia populnea on percentage of seed germination (%SG), germination speed index (GSI), length of rootlets (LR), seedling length (SL), and on dry mass (DM) of Bidens pilosa L weed.Methods: The powder of samaras was extracted with organic solvents providing the hexane (SAPEH), chloroform (SAPEC), ethyl acetate (SAPEAE) and ethanol (SAPEE) extracts. The terpene 1 was isolated from SAPEH by means of column and thin layer chromatography and identified through NMR spectroscopy. Each extract and 1 were subjected to growth inhibition assays evaluating the following parameters: %SG, GSI, LR, SL and DM, with five repetitions.Results: The compounds Friedelin (1), 7-hydroxy-clerodan-3-en-16,15:18,20-diolide (2), 3,5,7,4'-tetrahydroxy-6-methoxy-8-prenylflavanone (3), tetradecanamide (4), and 4-hydroxy-1,6,15-acetyloxy-8,9-benzoyloxy-agarofurane (5) were isolated from hexane extract of samaras of A. populnea and identified by spectroscopic data. The compounds 2, 3 and 5 were not previously described as being chemical constituents from Celastraceae family. In addition, the novel compounds 3 and 5 were described here for the first time. Substantial effect on the germination of B. pilosa L. (picão-preto) was observed after treatment of seeds with nonpolar extracts from Samaras of A. populnea. Friedelin inhibited the seed germination in the tested concentrations showing toxic properties against picão-preto.Conclusion: The germination inhibition of seeds was higher using nonpolar extracts than polar extract. Friedelin inhibited the seed germination in the tested concentrations showing toxic properties against B. pilosa.Â
Rational Design and Synthesis of Large Stokes Shift 2,6-Sulphur-Disubstituted BODIPYs for Cell Imaging
Five new disubstituted 2,6-thioaryl-BODIPY dyes were synthesized via selective aromatic electrophilic substitution from commercially available thiophenols. The analysis of the photophysical properties via absorption and emission spectroscopy showed unusually large Stokes shifts for BODIPY fluorophores (70–100 nm), which makes them suitable probes for bioimaging. Selected compounds were evaluated for labelling primary immune cells as well as different cancer cell lines using confocal fluorescence microscopy
The role of retailer's performance in optimal wholesale price discount policies
The main goal of this paper is to model the effects of wholesale price control on manufacturer’s profit, taking explicitly into account
the retailer’s sales motivation and performance. We consider a stylized distribution channel where a manufacturer sells a single kind of
good to a single retailer. Wholesale price discounts are assumed to increase the retailer’s motivation thus improving sales. We study the
manufacturer’s profit maximization problem as an optimal control model where the manufacturer’s control is the discount on wholesale
price and retailer’s motivation is one of the state variables. In particular in the paper we prove that an increasing discount policy is optimal
for the manufacturer when the retailer is not efficient while efficient retailers may require to decrease the trade discounts at the end of
the selling period. Computational experiments point out how the discount on wholesale price passed by the retailer to the market (passthrough)
influences the optimal profit of the manufacturer
Regularization Independent Analysis of the Origin of Two Loop Contributions to N=1 Super Yang-Mills Beta Function
We present a both ultraviolet and infrared regularization independent
analysis in a symmetry preserving framework for the N=1 Super Yang-Mills beta
function to two loop order. We show explicitly that off-shell infrared
divergences as well as the overall two loop ultraviolet divergence cancel out
whilst the beta function receives contributions of infrared modes.Comment: 7 pages, 2 figures, typos correcte
Measuring nutritional knowledge using Item Response Theory and its validity in European adolescents
Objective: To analyse the Nutritional Knowledge Test (NKT) using Item Response Theory (ITR) analysis and to assess the construct validity of the Nutritional Knowledge Scale (NKTS) and its associations with adolescent food group consumption and nutritional biomarkers.
DesignCross-sectional study: SettingMulticentre investigation conducted in ten European cities.ParticipantsAdolescents aged 12·5-17·5 years (n 3215) who completed over 75 % of the NKT.
Results: Factor analysis indicated that the NKT can be analysed with a one-dimensional model. Eleven out of twenty-three items from the NKT presented adequate parameters and were selected to be included in the NKTS. Nutrition knowledge was positively associated with consumption of fruits, cereals, dairy products, pulses, meat and eggs, and fish, as well as with blood concentrations of vitamin C, ß-carotene, n-3 fatty acids, holo-transcobalamin, cobalamin and folate; nutrition knowledge was negatively associated with intake of olives and avocado, alcohol and savoury snacks.
Conclusions: The NKTS assessed nutritional knowledge adequately and it is proposed as a new tool to investigate this subject in future studies
Polymer composites reinforced with natural fibers and nanocellulose in the automotive industry: a short review
Environmental concerns and cost reduction have encouraged the use of natural fillers as reinforcement in polymer composites. Currently, a wide variety of reinforcement, such as natural fibers and nanocellulose, are used for this purpose. Composite materials with natural fillers have not only met the environmental appeal, but also contribute to developing low-density materials with improved properties. The production of natural fillers is unlimited around the world, and many species are still to be discovered. Their processing is considered beneficial since the natural fillers do not cause corrosion or great wear of the equipment. For these reasons, polymer reinforced with natural fillers has been considered a good alternative for obtaining ecofriendly materials for several applications, including the automotive industry. This review explores the use of natural fillers (natural fibers, cellulose nanocrystals, and nanofibrillated cellulose) as reinforcement in polymer composites for the automotive industry323172016/09588-9; 2016/09588-9; 2016/09588-9CAPES - Coordenação de Aperfeiçoamento de Pessoal e NÃvel SuperiorCNPQ - Conselho Nacional de Desenvolvimento CientÃfico e TecnológicoFAPESP – Fundação de Amparo à Pesquisa Do Estado De São Paul
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