Evaluation of the photoelectrocatalytic method for oxidizing chloride and simultaneous removal of microcystin toxins in surface waters

The production of chlorine was investigated in the photoelectrocatalytic oxidation of a chloride-containing solution using a TiO(2) thin-film electrode biased at current density from 5 to 50 mA cm(-2) and illuminated by UV light. Such parameters as chloride concentrations from 0.001 to 0.10 mol L(-1), pH 2-12, and interfering salts were varied in this study in order to determine their effect on this oxidation process. At an optimum condition this photoelectrocatalytic method can produce active chlorine at levels compatible to water disinfections processes using a chloride concentration higher than 0.010 mol L(-1) at a pH of 4 and a current density of 30 mA cm(-2). The method was successfully applied to treat surface water collected from a Brazilian river. After 150 min of photoelectrocatalytic oxidation, we obtained a 90% reduction in total organic carbon removal, a 100% removal of turbidity, a 93% decrease in colour and a chemical oxygen demand (COD) removal of around 96% (N=3). The proposed technology based on photoelectrocatalytic oxidation was also tested in treating 250 mL of a solution containing 0.05 mol L(-1) NaCl and 50 mu g L(-1) of Microcystin aeruginosa. The bacteria is completely removed after 5 min of photoelectrocatalysis following an initial rate constant removal of -0.260 min(-1), suggesting that the present method could be considered as a promising alternative to chlorine-based disinfections. (C) 2008 Elsevier Ltd. All rights reserved.

Ethanolic extract of Casearia sylvestris and its clerodane diterpen (caseargrewiin F) protect against DNA damage at low concentrations and cause DNA damage at high concentrations in mice's blood cells

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

Hematological parameters in Nile Tilápia, Oreochromis niloticus exposed to sub-letal concentrations of mercury

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

Salt stress change chlorophyll fluorescence in mango

Este trabalho teve como objetivo avaliar o efeito do estresse salino sobre a eficiência fotoquímica do fotossistema II (PSII) nas cultivares de manga 'Haden', 'Palmer', 'Tommy Atkins' e 'Ubá' enxertadas sobre o porta-enxerto 'Imbu'. Foi utilizada solução nutritiva de Hoagland modificada contendo 0; 15; 30e 45 mmol L-1 NaCl. Aos 97 dias após a exposição ao estresse salino, foram avaliados os parâmetros da fluorescência da clorofila (F0, Fm, Fv, F0/Fm, Fv/Fm, Fv'/Fm', ΦPSII = [(Fm'-Fs)/(Fm')], D = (1- Fv'/Fm') e ETR = (ΦPSII×PPF×0,84×0,5). Aos 100 dias, foram avaliados a emissão foliar, a área média de folhas (cm²), o índice de toxidez nas folhas e o índice de abscisão foliar. em todas as cultivares, em graus diferenciados, ocorreram decréscimo na eficiência fotoquímica do fotossistema II, na emissão de folhas, e aumento nos índices de toxidez e abscisão foliar, intensificados nas concentrações a partir de 15 mmol L-1 NaCl. As plantas cultivadas em 45 mmol L-1 NaCl apresentaram decréscimos na razão Fv/Fm de 27,9; 18,7; 20,5 e 27,4%, incremento no índice de toxidez foliar de 33,0; 67,5; 41,6 e 80,8% e no índice de abscisão foliar de 71,8; 29,2; 32,5 e 67,9% para as cultivares 'Haden', 'Palmer', 'Tommy Atkins' e 'Uba', respectivamente. Os decréscimos na razão Fv/Fm foram acompanhados de redução na emissão de folhas e aumento no índice de toxidez foliar, mostrando, portanto, o potencial da fluorescência da clorofila na detecção precoce de estresse salino em mangueira.

ISOENZYMATIC POLYMORPHISM and ACTIVITY of PEROXIDASES of COMMON BEAN(Phaseolus vulgaris L.) UNDER SALINE STRESS

Uma das utilizações da técnica de cultura de tecidos para o melhoramento vegetal é a identificação de linhas de células que apresentem tolerância ao estresse salino. Para se estudar os mecanismos bioquímicos envolvidos na expressão genética da tolerância a salinidade, calos oriundos de eixos embrionários de quatro cultivares de feijão (Phaseolus vulgaris L.; cultivares IAC - carioca, IAPAR 14, JALO-EEP 558, BAT - 93), foram cultivados em meio sólido Murashige & Skoog (1962), suplementado com NaCl nas concentrações de 0, 20, 40, 60 e 80 mM. Após 14 dias de incubação, os calos foram coletados e analisados quanto aos padrões isoenzimáticos e de atividade das peroxidases. Os cultivares BAT e IAPAR apresentaram duas zonas de atividade em comum na região anódica e apenas uma zona enzimática específica a cada um deles (migração mais rápida).Possivelmente as duas zonas anódicas intermediárias sejam produtos do mesmo loco enzimático, porém com alelos diferentes, consequentemente diferentes mobilidades eletroforéticas. O cv. JALO apresentou duas zonas anódicas de atividade em comum com os cultivares IAC e IAPAR com uma zona anódica exclusiva de migração mais lenta, a qual apresentou atividade mais intensa de todos os cultivares analisados. Este cultivar revelou ainda uma zona catódica provavelmente dimérica e heterozigota nos indivíduos de todos os tratamentos aplicados. Provavelmente, esta é a mesma zona que ocorre em homozigose com fixação do alelo lento para os indivíduos de todos os tratamentos efetuados nos cultivares BAT e IAPAR. O cv. IAC apresentou duas bandas anódicas em comum com os cv. IAPAR e JALO. Apresentou também a banda anódica mais rápida em comum com o cv. IAPAR e uma banda anódica exclusiva de migração mais lenta. Curiosamente, os indivíduos deste cv. mantidos em meio suplementado com 20 mM de NaCl não apresentaram atividade nas três zonas anódicas mais lentas. Ocorreu no cv. IAC uma única zona de atividade catódica, dimérica e heterozigota para os indivíduos provenientes de todos os tratamentos, composta provavelmente de dois alelos diferentes da zona correspondente ao cv. JALO. Amostras provenientes dos tratamentos 40 e 60 mM de NaCl, desta zona catódica, apresentaram maior atividade enzimática. A análise da atividade da peroxidase no extrato bruto, revelou que os cultivares responderam diferentemente ao aumento da concentração salina no meio de cultura, com aumento pronunciado dessa atividade nos cultivares IAC e JALO.

POLIAMINAS E ATIVIDADE da PEROXIDASE em FEIJÃO (Phaseolus vulgaris L.) CULTIVADO SOB ESTRESSE SALINO

O teor de poliaminas (putrescina, espermidina e espermina) e a atividade enzimática da peroxidase (EC 1.11.1.7) foram determinados em plantas de Phaseolus vulgaris L. cv Carioquinha, após terem sido submetidas a estresse salino (50 e 100 mM de NaCl). Foram observadas alterações nos teores das poliaminas, principalmente putrescina, que aumentou com o tempo e a concentração de NaCl. Também ocorreu aumento na atividade da peroxidase em ambas concentrações de NaCl utilizadas. Os resultados mostraram alterações no metabolismo de poliaminas e peroxidases nas plantas de feijão cultivadas em meio salino.

Dynamics of follicle populations and gonadotropin concentrations in fillies age two to ten months

Follicle populations and concentrations of circulating gonadotropins were studied during age 2-10 months in 10 spring-born pony fillies. Blood sampling and ultrasound scanning were done every 4 days and daily for four 30 day periods. During 5-12 weeks, FSH concentrations were lower in 6 fillies with follicles greater than or equal to 6 mm (mean +/- s.e. 1.4 +/- 0.1 ng/ml) than in 4 fillies with follicles <6 mm (2.8 + 0.3 ng/ml). The diameters and numbers of follicles and gonadotropin concentrations increased progressively during age 2-4 months. A plateau in follicle activity and reduced levels of gonadotropins occurred during 5-7 months. During 8-10 months, follicles grew to >10 mm and gonadotropin concentrations increased. Waves of follicular growth were identified during the 30 day periods by significant increases in the diameter of the 10 largest follicles. The waves did not partition into dominant and subordinate follicles. Results indicated an initial postnatal period of negative ovarian feedback, temporally related changes in gonadotropins and follicles for months 3-10, and development of follicles in waves.

POSSIBLE MECHANISMS FOR REDUCTION OF CIRCULATING CONCENTRATIONS OF PROGESTERONE BY INTERFERON-ALPHA IN COWS - EFFECTS ON HYPERTHERMIA, LUTEAL CELLS, METABOLISM OF PROGESTERONE AND SECRETION OF LH

Experiments were performed to determine the mechanism by which recombinant bovine interferon-alpha(I)1 (rbIFN-alpha) causes an acute reduction in plasma concentrations of progesterone. In experiment 1, administration of a prostaglandin synthesis inhibitor blocked rbIFN-alpha-induced hyperthermia but did not prevent the decline in plasma concentrations of progesterone. The decline in progesterone concentrations caused by rbIFN-alpha was, therefore, not a direct consequence of the associated hyperthermia or of pathways mediated through prostaglandin synthesis. It is also unlikely that rbIFN-alpha acts to increase the clearance of progesterone since injection of rbIFN-alpha did not decrease plasma concentrations of progesterone in ovariectomized cows given an intravaginal implant of progesterone (experiment 2). In experiment 3, rbIFN-alpha did not affect basal and LH-induced release of progesterone from cultured luteal slices, indicating that rbIFN-alpha is unlikely to affect luteal function directly. Injection of rbIFN-alpha did, however, cause a decrease in plasma concentrations of LH in ovariectomized cows (experiment 4) that coincided temporally with the decrease in progesterone concentrations seen in cows having a functional corpus luteum. The present results strongly suggest that rbIFN-alpha acts to reduce secretion of progesterone by interfering with pituitary support for luteal synthesis of progesterone. The finding that rbIFN-alpha can inhibit LH secretion implies that interferon-alpha molecules should be considered among the cytokines that can regulate hypothalamic or pituitary function.

Effects of central alpha-adrenergic agonists on hormone-induced 3% NaCl and water intake

Male rats received intracerebroventricular (ICV) renin (600 ng) or daily subcutaneous injections of deoxycorticosterone (5 mg) to induce 3% NaCl and water intake. Noradrenaline (NOR; 40-160 nmol) and clonidine (CLO; 5-20 nmol) injected ICV. induced 70 to 100% inhibition of the intakes. Phenylephrine (PHE; 40-160 nmol) injected ICV induced 60 to 95% inhibition of the intakes. NOR and PHE induced a stronger inhibition on the 3% NaCl intake induced by renin than on the intake induced by deoxycorticosterone (DOC), and CLO did the opposite. CLO was always more effective than PHE to induce inhibition of the intakes. The results suggest that NOR inhibits hormone (angiotensin II, aldosterone)-induced NaCl intake by acting mainly on alpha(2)-adrenergic receptors.

Receptor-mediated effects of clonidine on need-induced 3% NaCl and water intake

Clonidine combined with adrenergic antagonists were injected in the medial septal area in order to characterize the type of receptors involved with its inhibitory effect on 3% NaCl and water intake of sodium-depleted (furosemide + 24 h of removal of ambient sodium) and 30-h water-deprived rats, respectively. The inhibitory effect of clonidine (20 nmol) on need-induced water intake was reduced 50% by an 80-nmol dose of either idazoxan, yohimbine or prazosin. The inhibitory effect of clonidine (30 nmol) on need-induced 3% NaCl intake was completely antagonized by idazoxan (80, 160 nmol), not altered by yohimbine (40-160 nmol), and partially potentiated (40 nmol) or inhibited (160 nmol) by prazosin. Propranolol did not alter the effects of clonidine on either water (80 nmol) or 3% NaCl (40-160 nmol) intake. The results suggest that the inhibitory effects of clonidine on 3% NaCl and water intake are mediated by different types of alpha2-adrenergic receptors. Copyright (C) 1997 Elsevier B.V.

Influence of two methods of CaCl2 application and concentrations used to maintain passion fruit firmness

This is a report on the influence of the methods of postharvest application of CaCl2 in several concentrations, on the maintenance of the firmness of the sweet passion fruit (Passiflora alata Dryander). The fruits, picked in the pre-climateric stage, were selected desinfection with thiabendazol and submitted to CaCl2 in concentrations of 0% (control), 1%, 2%, 3% or 4% with two methods: immersion (for 2 h) and infiltration under vacuum and pressure (- 25 vacuum kPa, for 1 minute and, + 25 pressure kPa, for 1 min). All fruits were stored under refrigeration (9 degreesC, 85-90% RH), for 30 d. The fruits were evaluated for texture every 3 d. From the results, it is concluded that application of CaCl2 by infiltration favored the maintenance of fruit consistency during the first 18 days of storage. Fruits treated with 1% and 2% of CaCl2 were firmer than the others.

Siloxane-polypropyleneoxide hybrid ormolytes: structure-ionic conductivity relationships

Siloxane-polypropyleneoxide (PPO) hybrids doped with sodium perchlorate (NaClO4) obtained by the sol-gel process were prepared with two PPO molecular weights (2000 and 4000 g/mol) and two sodium concentrations such as [O]/[Na] = 4 and 15 (O being the ether-type oxygen of PPO chains). The structure of these hybrids was investigated by Na-23 nuclear magnetic resonance (NMR) and X-ray absorption spectroscopy at the sodium K-edge (1071.8 eV) whereas complex impedance spectroscopy was used to determine their ionic conductivity. Three sodium sites were determined by NMR. The conjunction of NMR and X-ray absorption results allows us to identify one site in which Na is in a NaCl structure, a second one in which Na is in contact with perchlorate anions. The third site is attributed to mobile sodium species in interaction with the polymeric chain. The relative proportion of the different sites in the materials determines the ionic conductivity of the materials at room temperature: the largest ionic conductivity is 8.9 x 10(-6) Omega(-1) cm(-1) and is observed on the material with the larger amount (at least 85%) of sites in which sodium interacts with the polymer. (C) 2002 Elsevier B.V. B.V. All rights reserved.

Diffusion coefficients during osmotic dehydration of tomatoes in ternary solutions

The apparent diffusion coefficients for sucrose, NaCl and water during osmotic dehydration of tomatoes in ternary solutions were determined. Long time experiments (up to 60 h) were carried out in order to determine equilibrium concentrations inside tomatoes, whereas short time experiments (up to 4 h) were performed to provide detailed information on kinetics of water loss and solids gain at the beginning of osmotic treatment. The mass transfer rates for water and solutes showed to be dependent of NaCl and sucrose concentrations in osmotic solution and simple regression models as functions of solutes concentration were determined for diffusion coefficients. Salt and sucrose diffusivities showed to be interdependent, with increasing NaCl concentration causing the enhancement of water loss, at the same time that higher sucrose contents hindered the excessive salt penetration. (C) 2003 Elsevier Ltd. All rights reserved.