Modelo teórico e experimental da reciclagem do Carbono-13 em tecidos de mamíferos e aves

A diferença entre fontes alimentares da ordem de 14 , originárias de plantas com ciclos fotossintéticos Carbono-3 (C3) e Carbono-4 (C4) e seus subprodutos, abre novas perspectivas para o estudo do metabolismo do carbono em aves e animais de pequeno porte. Os autores propõem um modelo teórico e experimental capaz de exprimir os resultados de enriquecimento relativo, delta per mil (delta ) da razão 13C/12C versus tempo em diferentes tecidos. Utilizou-se a equação y(t) = (y0 -- q/k) e-kt + q/k onde, y(t) é a concentração isotópica no tempo desejado, y0 a concentração isotópica inicial existente no tecido, k é uma constante de troca isotópica com unidade 1/tempo, t é unidade de tempo e q é a taxa de entrada de metabólitos que contém carbono, com valores de delta /tempo. Para fígado de galinhas que tiveram a ração de ciclo fotossintético C4 substituída por dieta C3 obteve-se a equação delta13C = -24,74 + 12,37 e-0.237(nT), com meia-vida (T) de 2,9 dias. O patamar de equilíbrio de substituição do carbono foi alcançado em --24,48 , de modo que praticamente 98,4% do conteúdo isotópico do C4 no fígado foi substituído por C3 após 5,6 meias-vidas. O modelo foi adequado para determinar o tempo de reciclagem total ou parcial da concentração de carbono nos tecidos em estudo.

Persistence of insecticide residues in olives and olive oil

The decay rate of six insecticides (azinphos methyl, diazinon, dimethoate, methidathion, parathion methyl, and quinalphos) used to control Dacus oleae was studied. Degradation of pesticides showed pseudo-first-order kinetics with correlation coefficients ranging between -0.936 and -0.998 and half-lives between 4.3 days for dimethoate and 10.5 days for methidathion. Residues in olive oil were greater than on olives, with a maximum concentration factor of 7. Dimethoate was the only pesticide with lower residues in the oil than on the fruits. Olive washing affects pesticide residues ranging from no reduction to a 45% decrease. During 8 months of storage of the olive oil, diazinon, dimethoate, parathion methyl, and quinalphos did not show any remarkable difference, while methidathion and azinphos methyl showed a moderate decrease.

Lability of heavy metal species in aquatic humic substances characterized by ion exchange with cellulose phosphate

Labile metal species in aquatic humic substances (HSs) were characterized by ion exchange on cellulose phosphate (CellPhos) by applying an optimized batch procedure. The HSs investigated were pre-extracted from humic-rich waters by ultrafiltration and a resin XAD 8 procedure. The HS-metal species studied were formed by complexation with Cd(II), Ni(II), Cu(II), Mn(II) and Pb(II) as a function of time and the ratio ions to HSs. The kinetics and reaction order of this exchange process were studied. At the beginning (<3 min), the labile metal fractions are separated relatively quickly. After 3 min, the separation of the metal ions proceeds with uniform half-lives of about 12-14 min, revealing rather slow first-order kinetics. The metal exchange between HSs and CellPhos exhibited the following order of metal lability with the studied HSs: Cu > Pb > Mn > Ni > Cd. The required metal determinations were carried out by atomic absorption spectrometry.

Production of extracellular alkaline proteases by Aspergillus clavatus

The production of extracellular alkaline proteases from Aspergillus clavatus was evaluated in a culture filtrate medium, with different carbon and nitrogen sources. The fungus was cultivated at three different temperatures during 10 days. The proteolytic activity was determined on casein pH 9.5 at 37degreesC. The highest alkaline proteolytic activity (38 U/ml) was verified for culture medium containing glucose and casein at 1% (w/v) as substrates, obtained from cultures developed at 25degreesC for 6 days. Cultures developed in Vogel medium with glucose at 2% (w/v) and 0.2% (w/v) NH4NO3 showed higher proteolytic activity (27 U/ml) when compared to the cultures with 1% of the same sugar. Optimum temperature was 40degreesC and the half-lives at 40, 45 and 50degreesC were 90, 25 and 18 min, respectively. Optimum pH of enzymatic activity was 9.5 and the enzyme was stable from pH 6.0 to 12.0.

Resíduos de fentoato em tomate

The objective of the present research was to study the degradation and the persistence of phenthoate (Elsan 50 CE) residues in tomato fruits. The experiment was set in a tomato field located in Mombuca, State of São Paulo, Brazil, after 45 days from seedlings transplantation. Dosages of 600 (A), 800 (B), 1200 (C) and 1600 g a.i./ha (D) were sprayed at the beginning of the ripening period of fruits. Samples of 15 fruits each were collected 1, 4, 10, 20 and 40 days after products spraying. The utilized procedure consisted of extraction with acetone and purification by partition with dichloromethane. The purified extract was concentrated and injected into a gas chromatograph equipped with alkaly flame ionization detector (AFID). The limits of detection were of 0,01 ppm for this product. The recovery percentage from fortified samples varied from 60 to 81%. The degradation and the persistence half-lives were 1 to 2 and 3 to 6 days for phenthoate, respectively.

Thermostable invertases from Paecylomyces variotii produced under submerged and solid-state fermentation using agroindustrial residues

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

Pectin lyase from Aspergillus giganteus: Comparative study of productivity of submerged fermentation on citrus pectin and orange waste

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

Environmental Behaviour of Metolachlor and Diuron in a Tropical Soil in the Central Region of Brazil

The environmental behaviour of metolachlor and diuron was studied in the Central-western region of Brazil, by means of a field study where six experimental plots were installed. The soil was classified as a Latosol, and the soil horizons were characterized. Sorption of metolachlor and diuron was evaluated in laboratory batch experiments. Metolachlor and diuron were applied to the experimental plots on uncultivated soil in October 2003. From this date to March 2004, the following processes were studied: leaching, runoff and dissipation in top soil. K (oc) of metolachlor varied from 179 to 264 mL g(-1) in the soil horizons. K (oc) of diuron in the Ap horizon was 917 mL g(-1), decreasing significantly in the deeper horizons. Field dissipation half-lives of metolachlor and diuron were 18 and 15 days, respectively. In percolated water, metolachlor was detected in concentrations ranging from 0.02 to 2.84 mu g L-1. In runoff water and sediment, metolachlor was detected in decreasing concentrations throughout the period of study. Losses of 0.02% and 0.54% of the applied amount by leaching and runoff, respectively, were observed confirming the high mobility of this herbicide in the environment. In percolated water, diuron was detected with low frequency but in relatively high concentrations (up to 6.29 mu g L-1). In runoff water and soil, diuron was detected in decreasing concentrations until 70 days after application, totalizing 13.9% during the whole sampling period. These results show the importance of practices to reduce runoff avoiding surface water contamination by these pesticides, particularly diuron.

Fate of Some New Fungicides (Cyprodinil, Fludioxonil, Pyrimethanil, and Tebuconazole) from Vine to Wine

The fate of four new fungicides (cyprodinil, fludioxonil, pyrimethanil, and tebuconazole) from the treatment on vine to the production of wine was studied. The influence of clarifying agents (bentonite, charcoal, potassium caseinate, gelatin, and polyvinylpolypyrrolidone) on residue concentrations in wine was also studied. The fungicide residues on grapes showed different decay rates after treatment, with first-order kinetics and half-lives ranging from 8 to 57 days. Grape processing into wine caused considerable residue reduction with cyprodinil (ca. 80%), fludioxonil (ca. 70%), and tebuconazole (ca. 50%) and no reduction with pyrimethanil. The two wine-making techniques employed (with and without maceration) had the same influence on the residue concentrations in wine, except for fludioxonil which showed maximum residue reduction with vinification with maceration. Among the clarifying agents tested, only charcoal showed effective action on the elimination of residue content in wine, proving complete elimination, or almost, of fungicide residues.

Residues of Some Pesticides in Fresh and Dried Apricots

The persistence of three pesticides (fenitrothion, dimethoate, and ziram) in apricots in field conditions and their fate during the drying process were studied. After the treatments, the pesticides showed fast decay rates with pseudo-first-order kinetics and half-lives ranging from 6.9 to 9.9 days. The drying process showed a different effect on residue concentrations in dried apricots: omethoate (metabolite of dimethoate) and ziram residues had almost doubled, while fenitrothion disappeared and dimethoate remained constant.

Kaposi's sarcoma-associated herpesvirus latency-associated nuclear antigen 1 mimics Epstein-Barr virus EBNA1 immune evasion through central repeat domain effects on protein processing

Kaposi's sarcoma-associated herpesvirus (KSHV/human herpesvirus 8 [HHV8]) and Epstein-Barr virus (EBV/HHV4) are distantly related gammaherpesviruses causing tumors in humans. KSHV latency-associated nuclear antigen 1 (LANA1) is functionally similar to the EBV nuclear antigen-1 (EBNA1) protein expressed during viral latency, although they have no amino acid similarities. EBNA1 escapes cytotoxic lymphocyte (CTL) antigen processing by inhibiting its own proteosomal degradation and retarding its own synthesis to reduce defective ribosomal product processing. We show here that the LANA1 QED-rich central repeat (CR) region, particularly the CR2CR3 subdomain, also retards LANA1 synthesis and markedly enhances LANA1 stability in vitro and in vivo. LANA1 isoforms have half-lives greater than 24 h, and fusion of the LANA1 CR2CR3 domain to a destabilized heterologous protein markedly decreases protein turnover. Unlike EBNA1, the LANA1 CR2CR3 subdomain retards translation regardless of whether it is fused to the 5′ or 3′ end of a heterologous gene construct. Manipulation of sequence order, orientation, and composition of the CR2 and CR3 subdomains suggests that specific peptide sequences rather than RNA structures are responsible for synthesis retardation. Although mechanistic differences exist between LANA1 and EBNA1, the primary structures of both proteins have evolved to minimize provoking CTL immune responses. Simple strategies to eliminate these viral inhibitory regions may markedly improve vaccine effectiveness by maximizing CTL responses. Copyright © 2007, American Society for Microbiology. All Rights Reserved.

Characterization of a tannase from Emericela nidulans immobilized on ionic and covalent supports for propyl gallate synthesis

The extracellular tannase from Emericela nidulans was immobilized on different ionic and covalent supports. The derivatives obtained using DEAE-Sepharose and Q-Sepharose were thermally stable from 60 to 75 °C, with a half life (t50) >24 h at 80 °C at pH 5. 0. The glyoxyl-agarose and amino-glyoxyl derivatives showed a thermal stability which was lower than that observed for ionic supports. However, when the stability to pH was considered, the derivatives obtained from covalent supports were more stable than those obtained from ionic supports. DEAE-Sepharose and Q-Sepharose derivatives as well as the free enzyme were stable in 30 and 50 % (v/v) 1-propanol. The CNBr-agarose derivative catalyzed complete tannic acid hydrolysis, whereas the Q-Sepharose derivative catalyzed the transesterification reaction to produce propyl gallate (88 % recovery), which is an important antioxidant. © 2012 Springer Science+Business Media Dordrecht.

The no-tillage system and cover crops-Alternatives to increase upland rice yields

Upland rice (Oryza sativa L.) cultivation has been increasing in importance in Asia while water availability for irrigation has been decreasing because of rapid growth in industry and urban centers. Therefore, the development of technologies that increase upland rice yields under aerobic conditions, thereby saving water, would be an effective strategy to avoid a decrease in global rice grain production. The use of the no-tillage system (NTS) and cover crops that maintain soil moisture would prove advantageous in the move toward sustainable agriculture. However, upland rice develops better in plowed soil, and it has been reported that this crop does not perform well under the NTS. Therefore, the aim of this study was to investigate the effect of cover crops on upland rice grain yield and yield components sowed in a NTS. A field experiment was conducted during two growing seasons (2008-2009 and 2009-2010), and treatments consisted of growing rice under five cover crops in a NTS and two control treatments under the conventional tillage system (plowing once and disking twice). Treatments were carried out in a randomized block design with three replications. Our findings are as follows: On average, Brachiaria brizantha (12.32Mgha-1), Brachiaria ruziziensis (11.08Mgha-1) and Panicum maximum (11.62Mgha-1) had outstanding biomass production; however, these grasses provided the worst upland rice yields (2.30, 2.04, and 2.67Mgha-1, respectively) and are not recommended as cover crops before upland rice. Millet and fallow exhibited the fastest straw degradation (half-lives of 52 and 54 days, respectively), and millet exhibited the fastest nitrogen release (N half-life of 28 days). The use of a NTS was promising when millet was used as a cover crop; this allowed the highest upland rice yield (3.94Mgha-1) and did not statistically differ from plowed fallow (3.52Mgha-1). © 2012 Elsevier B.V.

Produção e caracterização do complexo xilanolítico de Penicillium janczewskii

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)

Avaliação metabólica de dietas de C3 e C4 na formação do ovo (gema e albúmen) pelo uso da técnica dos isótopos estáveis do carbono

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)