Esterase profile in the postembryonic development of Rhipicephalusmicroplus

The objective of this work was to analyze the pattern of esterase activity in the development stages of Rhipicephalus microplus by nondenaturing polyacrylamide gel electrophoresis using specific staining for esterase. The electrophoretical results revealed the presence of nine regions displaying esterase activity, stained with both alpha-naphthyl acetate and beta-naphthyl acetate, and classified as alpha-beta-esterase. Stage-specific esterases were found, with the first nymphal and larval stages showing the greatest esterase activity throughout the development. An esterase called EST-4 was detected only in males and was considered sex-specific. There are differences in the esterase profile among the different postembryonic development stages of R. microplus.

Potential of antimicrobial volatile organic compounds to control Sclerotinia sclerotiorum in bean seeds

The objective of this work was to evaluate the potential of an artificial mixture of volatile organic compounds (VOCs), produced by Saccharomyces cerevisiae, to control Sclerotinia sclerotiorum in vitro and in bean seeds. The phytopathogenic fungus was exposed, in polystyrene plates, to an artificial atmosphere containing a mixture of six VOCs formed by alcohols (ethanol, 3-methyl-1-butanol, 2-methyl-1-butanol and phenylethyl alcohol) and esters (ethyl acetate and ethyl octanoate), in the proportions found in the atmosphere naturally produced by yeast. Bean seeds artificially contamined with the pathogen were fumigated with the mixture of VOCs in sealed glass flasks for four and seven days. In the in vitro assays, the compounds 2-methyl-1-butanol and 3-methyl-1-butanol were the most active against S. sclerotiorum, completely inhibiting its mycelial growth at 0.8 µL mL-1, followed by the ethyl acetate, at 1.2 µL mL-1. Bean seeds fumigated with the VOCs at 3.5 µL mL-1 showed a 75% reduction in S. sclerotiorum incidence after four days of fumigation. The VOCs produced by S. cerevisiae have potential to control the pathogen in stored seeds.

Trichogramma pretiosum attraction due to the Elasmopalpus lignosellus damage in maize

The objective of this work was to evaluate if corn plants damaged by the lesser cornstalk borer (Elasmopalpus lignosellus) larvae release volatile organic compounds capable of attracting the egg parasitoid Trichogramma pretiosum. The treatments consisted of plants subjected to harm caused by E. lignosellus larvae, plants subjected to mechanical damage, and undamaged plants. The parasitoid was more attracted by the volatiles released by the insect damaged plants than to those released by undamaged corn plants, after 24 and 72 hours. The volatiles (Z)-3-hexenyl acetate, β-pinene, β-myrcene, (E)-4,8-dimethylnona-1,3,7-triene, and benzothiazole were released in significantly larger quantities by damaged plants. Volatiles released by corn plants damaged by E. lignosellus larvae may act as an indirect defense, attracting by T. pretiosum.

Vitamina A em dieta de juvenis de pacu cultivados em tanques-rede

O objetivo deste trabalho foi avaliar o efeito da suplementação de vitamina A na alimentação de juvenis de pacu cultivados em tanques-rede. Foram utilizados 2.000 peixes, com peso inicial médio de 66,93±15,03 g, distribuídos em delineamento inteiramente casualizado, em 20 tanques-rede de 5,0 m³, com cinco tratamentos e quatro repetições. As rações foram formuladas com 0, 3.000, 6.000, 9.000 e 12.000 UI de vitamina A por quilograma de dieta, por meio da suplementação com acetato de retinol. O arraçoamento foi realizado às 8:30, 13:30 e 17:30 h, até a saciedade aparente dos animais. Não foram observadas diferenças quanto aos parâmetros de desempenho produtivo, rendimento e composição química da carcaça, e aos parâmetros hematológicos e lipídios no fígado dos peixes que foram alimentados com diferentes níveis de vitamina A. A suplementação de vitamina A em dietas para juvenis de pacu criados em tanques-rede não influencia o desempenho produtivo dos peixes.

Preferential reproduction mode of hermaphrodite papaya plant (Carica papaya L; Caricaceae)

This research was done to study the reproductive system of papaya hermaphrodite plant based on the histochemical nature of pollen grain, stigma receptivity, in vivo pollen grain germination and pollen:ovule ratio. In the histochemical analysis, pollen grains were stained by using Sudan IV and I2KI solution ; the stigma receptivity was assessed by alpha-naphthtyl acetate solution in closed and opened flowers. Pollen germination and pollen tube growing were examined in flower buds near anthesis with 0.1% aniline blue. To estimate the pollen:ovule ratio , anthers from each flower bud were dissected and all pollen grains were counted; ovules were dissected from ovaries and were counted under stereomicroscope. The results indicated that papaya pollen grains are of lipidic nature; the stigmas were receptive before the opening and until 48 hours after opening; the pollen grains germinated and emitted polinic tube before flower opening and the pollen:ovule ratio indicated the predominance of autogamous reproductive system. These results indicate that hermaphrodite papaya trees is preferentially of optional autogamous with cleistogamy.

Ésteres triterpênicos de Himatanthus sucuuba (Spruce) Woodson

Bioactivity-guided fractionation from hexane extract of Himatanthus sucuuba barks utilizing Cladosporium sphaerospermum led to the isolation of iridoids plumericin and isoplumericin, which showed higher inhibition against C. sphaerospermum than the antibiotic nistatin. Besides bioactive iridoids were isolated the inactive triterpenes lupeol cinnamate, alpha-amyrin cinnamate and lupeol acetate.

Triterpenos esterificados com ácidos graxos e ácidos triterpênicos isolados de Byrosonima microphylla

The hexane extract of leaves of B. microphylla afforded a mixture of triterpenes esterified with fatty acids. Analyses of spectral data of the mixture and of the derivatives obtained by a transesterification reaction with NaOMe/MeOH permitted to identify the composition of the mixtures as being 24-hydroxy-urs-12-enyl 3b-eicosanate, estearate and palmitate as well as of the 24-hydroxy-olean-12-enyl 3b-eicosanate, estearate and palmitate. From the choroform and ethyl acetate extracts were isolated the oleanolic and 3b,24-dihydroxy-urs-12-en-28-oic acids, quercetin and methyl galic ester, respectively. The compounds were identified through analysis of their spectral data.

Propriedades e aplicações de clusters trinucleares de carboxilatos de rutênio

A review with 94 references focusing on mu3-oxo-triruthenium carboxylate clusters is presented. The electronic, magnetic, electrochemical, and catalytic properties of these compounds are discussed. Main synthetic routes and structural characteristics, including their use as building blocks in supramolecular systems are described.

Combinación de sistemas de flujo de baja y alta presion para la determinacion de Mg, Ca y Sr en salmueras por espectrofotometria de absorcion atomica con llama

This article describes the combination of low- and high-pressure flow systems for the determination of Magnesium, Calcium and Strontium by flame atomic absorption spectrometry (FAAS). In the low-pressure system a short C-18 RP column (length 0,5 cm) was utilized for the preconcentration/matrix separation step, xylenol orange was used as chelating agent and tetrabutylamonium acetate for ion pair formation. The hydraulic high pressure nebulization (HHPN) was used for sample transport and sample introduction in the high pressure system. The repeatabilities and detection limits for Mg, Ca and Sr were determined and compared with those obtained by pneumatic nebulization (PN). The results show that the detection limits obtained using the HHPN for Mg, Ca and Sr are between 1.5 to 2 times better than those obtained by PN when the signal transient was measured in area. The system presented a sampling frequency of 130 h-1 for direct determination of Mg, Ca or Sr in samples of saturated sodium chloride used in the production of chlorine and sodium hydroxide.

Uma célula eletroquímica de fluxo para modificação permanente de tubo de grafite empregado em absorção atômica

A flow cell assembled on the original geometry of a graphite tube to achieve permanent chemical modifier is proposed. The graphite tube operates as the working electrode. A stainless steel tube, positioned downstream from the working electrode, was used as the auxiliary electrode. The potential value applied on the graphite electrode was measured against a micro reference electrode (Ag/AgCl) inserted into the auxiliary electrode. Palladium solutions in acetate buffer (100 mmol L-1, pH = 4.8), flowing at 0.5 mL min-1 for 60 min was used to perform the electrochemical modification. A mercury solution (1 ng) was used to evaluate the performance of the permanent palladium modifier.

Análise de resíduos de pesticidas em tomates por cromatografia em camada delgada

Pesticide residues are determined by thin layer chromatography (TLC) using the Hill reaction as a detection method. Tomatoes samples without pesticide were fortified with atrazine, diuron, chloroxuron and metribuzin, and were applyed in silica gel plates with the help of a microsyringe. The pesticides were elued with ethyl acetate. There was no need of cleaning up because no interference was noticed. After the revelation of the plates, the diameters of the spots were measure by using a rule. The range of the determined concentration for all the pesticides was from 0.1 to1.0 ng/muL. The results obtained through TLC can be used for semi-quantitative analysis.The results obtained were compared to gas and liquid chromatography, showing good agreement between both techniques.

Obtenção e caracterização de blendas colágeno-quitosana

Biodegradable polymer blends were obtained using collagen and chitosan. Membranes of collagen and chitosan in different proportions (3:1, 1:1 and 1:3) were prepared by mixing their acetate solutions (pH 3.5) at room temperature. The blends were characterized by differential scanning calorimetry (DSC), thermogravimetric analysis (TGA), Fourier Transform infrared (FTIR) spectroscopy, specific viscosity, water absorption and stress-strain assays. The results showed that chitosan did not interfere in the structural arrangement of the collagen triple helix and the properties of the blends can be controlled by varing the proportion of the collagen and the chitosan.

Dirhamnosyl flavonoid and other constituents from Brillantaisia palisatii

A mixture containing sitosterol and stigmasterol; a new triterpene 3-epi-ursolic acid; another triterpene mixture comprising a-amyrin, b-amyrin and lupeol; verbascoside, a phenylpropanoid glycoside; and lespedin, a glycosyl flavonoid, were isolated. The less polar compounds (steroids and triterpenoids) were isolated from the hexane partition of the crude ethanolic extract while the more polar ones (phenylpropanoid glycoside and glycosyl flavonoid) were isolated from the ethyl acetate partition of the same extract. The structures of all compounds were established using modern spectrometric methods of elucidation. The spectroscopic data of Lespedin, a rare dirhamnosylflavonol with hypotensor activity and of the triterpene, 3-epi-ursolic acid, are also reported.

A simplified procedure for determination of clofentezine residues in fruits by liquid chromatography with UV detection

A rapid and sensitive method is described for the determination of clofentezine residues in apple, papaya, mango and orange. The procedure is based on the extraction of the sample with a hexane:ethyl acetate mixture (1:1, v/v) and liquid chromatographic analysis using UV detection. Mean recoveries from 4 replicates of fortified fruit samples ranged from 81% to 96%, with coefficients of variation from 8.9% to 12.5%. The detection and quantification limits of the method were of 0.05 and 0.1 mg kg-1, respectively.

Determinación de cinc a microescala en un medicamento especifico

This work presents zinc determination in certain medicines that contain zinc oxide and zinc undecylenate. The technique consists of a spectrophotometric micro-scale titration, where EDTA is used as titrant, and xylenol orange as an indicator, in a medium adjusted to pH = 6 with acetic acid and sodium acetate. After each added portion of EDTA, the absorbance value is measured at a selected wavelength, in order to detect the end-point of the spectrophotometric titration. The results already obtained are satisfactory and promote student's interest. An additional contribution intends to propose the use of micro-scale techniques.