Changes induced by malathion, methylparathion and parathion on membrane lipid physicochemical properties correlate with their toxicity

Perturbations induced by malathion, methylparathion and parathion on the physicochemical properties of dipalmitoylphosphatidylcholine (DPPC) were studied by fluorescence anisotropy of DPH and DPH-PA and by differential scanning calorimetry (DSC). Methylparathion and parathion (50 [mu]M) increased the fluorescence anisotropy evaluated by DPH-PA and DPH, either in gel or in the fluid phase of DPPC bilayers, but mainly in the fluid phase. Parathion is more effective than methylparathion. On the other hand, malathion had almost no effect. All the three xenobiotics displaced the phase transition midpoint to lower temperature values and broadened the phase transition profile of DPPC, the effectiveness following the sequence: parathion>methylparathion>>malathion. A shifting and broadening of the phase transition was also observed by DSC. Furthermore, at methylparathion/lipid molar ratio of 1/2 and at parathion/lipid molar ratio of 1/7, the DSC thermograms displayed a shoulder in the main peak, in the low temperature side, suggesting coexistence of phases. For higher ratios, the phase transition profile becomes sharp as the control transition, but the midpoint is shifted to the previous shoulder position. Conversely to methylparathion and parathion, malathion did not promote phase separation. The overall data from fluorescence anisotropy and calorimetry indicate that the degree of effect of the insecticides on the physicochemical membrane properties correlates with toxicity to mammals. Therefore, the in vivo effects of organophosphorus compounds may be in part related with their ability to perturb the phospholipid bilayer structure, whose integrity is essential for normal cell function.http://www.sciencedirect.com/science/article/B6T1T-42NY32W-K/1/9c5c8320a8dff42bbf122281b5056b8

Cytotoxicity and Membrane Interaction of Tamoxifen as Affected by Ca2+ and Mg2+: Use of a Bacterial Model System

A strain of Bacillus stearothermophilus was used as a model to study the interaction of tamoxifen (TAM) with the membrane and the cytostatic antiproliferative effects not related to estrogen binding. TAM inhibits the growth of B. stearothermophilus as a function of concentration. The supplementation of the growth medium with Ca2+ or Mg2+ partially relieves the growth inhibition by TAM, allowing growth at TAM concentrations that fully impair growth in the basal medium. Fluorescence polarization of 1,6-diphenyl-1,3,5-hexatriene (DPH) and of its propionic acid derivative (DPH-PA) reveals opposite effects induced by TAM and Ca2+. The addition of Ca2+ to liposomes of bacterial lipids promoted physical ordering as opposed to disordering induced by TAM. Thus, it is predictable that growth impairment induced by TAM is mediated through perturbations at the membrane level.http://www.sciencedirect.com/science/article/B6TCP-3X3K8KK-Y/1/c91ad40c71c69da7245d8f09c634d28

Traditional vegetables: preliminary studies on seeds of vinegar (Hibiscus sabdariffae L.).

Abstract 96

Conjugated linoleic acid reduces permeability and fluidity of adipose plasma membranes from obese Zucker rats

NOTICE: this is the author’s version of a work that was accepted for publication in Biochemical and Biophysical Research Communications. Changes resulting from the publishing process, such as peer review, editing, corrections, structural formatting, and other quality control mechanisms may not be reflected in this document. Changes may have been made to this work since it was submitted for publication. A definitive version was subsequently published in Biochemical and Biophysical Research Communications. July 2010; 398 (2): 199-204.Conjugated linoleic acid (CLA) is a dietary fatty acid frequently used as a body fat reducing agent whose effects upon cell membranes and cellular function remain unknown. Obese Zucker rats were fed atherogenic diets containing saturated fats of vegetable or animal origin with or without 1% CLA, as a mixture of cis(c)9,trans(t)11 and t10,c12 isomers. Plasma membrane vesicles obtained from visceral adi- pose tissue were used to assess the effectiveness of dietary fat and CLA membrane incorporation and its outcome on fluidity and permeability to water and glycerol. A significant decrease in adipose membrane fluidity was correlated with the changes observed in permeability, which seem to be caused by the incor- poration of the t10,c12 CLA isomer into membrane phospholipids. These results indicate that CLA supple- mentation in obese Zucker rats fed saturated and cholesterol rich diets reduces the fluidity and permeability of adipose membranes, therefore not supporting CLA as a body fat reducing agent through membrane fluidification in obese fat consumers

A moenda da azeitona e as características físico-químicas dos azeites virgens

Comunicação apresentada no III Simpósio Nacional de Olivicultura que decorreu em Castelo Branco na Escola Superior Agrária do Instituto Politécnico de Castelo Branco, de 29 a 31 de Outubro de 2003.No presente trabalho estudou-se a influência do tipo de moenda da azeitona nas características do azeite virgem, comparando os azeites obtidos extraídos por moinho de pedras e por moinho metálico de martelos (com grelhas 5 e 7 mm de diâmetro). A azeitona foi processada numa linha Rapanelli . A qualidade dos azeites foi avaliada por determinação de: acidez, índice de peróxido, absorvâncias no UV, composição em ácidos gordos, estabilidade oxidativa, K225, pigmentos clorofilinos, cor (L*a*b*) e polifenóis totais. Em geral, a moenda não influencia os parâmetros de qualidade dos azeites, dependendo mais das cultivares constituintes dos lotes. Os resultados mostram que quando se utilizam moinhos de martelos se obtêm azeites virgens com um teor superior de pigmentos clorofilinos

Sensory profiling of complex meals : the case study of baked cod with cream and duck

Sensory analysis provides important information for developing new products and improving existing ones on the market. In fact, this science appears as a link between research and the development of innovative foods and their acceptance by the consumer [1]. The main purpose of this study is to evaluate the effectiveness of sensory methodologies for profiling of complex meals such as baked cod with cream and duck rice. Evaluation was performed with two sets of eight samples of industrial cod with cream and duck rice. Two independent trained panels of 9 and 12 judges evaluated the samples according to Quantitative Descriptive Analysis (QDA). Two independent panels of 16 untrained judges applied the Flash-Profile (FP) methodology over four sessions: attribute generation; final attribute list choice; evaluation 1 and 2. Two consumer panels evaluated the overall acceptance of each set of samples, on a sequential monadic presentation. For duck rice meals, the correlation between QDA and FP was not high (RV=0,646), and consumers preferred samples characterized by rice colour intensity, amount of duck, oiliness, bacon and chorizo in the meal. For cod with cream meals, the consumers preferred the samples characterized by amount and size of the cod pieces and intensity of cod taste, with a high correlation between FP and QDA (RV=0,860). Both sensory descriptive methodologies provide us with reliable and robust data in the characterization of complex meals. The FP methodology is relevant when working with panels of consumers to the extent that allows it to use their own lexicon of attributes. The application of external preference mapping on consumers’ response to FP emerges as a quick tool, either to describe products or to be used by food companies that have difficulties in using trained assessors’ panels. References: [1] Siegrist, M. (2008) Factors influencing public acceptance of innovative food technologies and products. Trends in Food Science & Technology, 19, 603-608

Comparative study of tributyltin toxicity on two bacteria of the genus Bacillus

Tributyltin is a potent biocide mainly used in marine antifouling paints. Owing to its widespread distribution in coast areas and its high toxicity to aquatic organisms, the use of this compound is generally restricted and under government regulation. Despite of that, it persists in the aquatic environment. Organotins used in industry have also been detected in terrestrial environments. The persistence and high lipophilicity explain bioaccumulation. The role of bacteria in recycling organic matter prompted us to study the interaction of tributyltin with two ubiquitous bacilli, B. stearothermophilus and B. subtilis, proposed as biological indicators of pollutants with ecological impact. These bacteria have been used as suitable models for the study of toxicity mechanisms of unselective lipophilic compounds (e.g., DDT and endosulfan). Drug effects on growth parameters, oxygen consumption and membrane organization were assessed. Bacteria growth in a liquid complex medium was disturbed by concentrations of TBT as low as 25 nM (8 [mu]g L-1), close to the concentration in polluted environments. The respiratory activity is affected by TBT in both microorganisms. Membrane organization, assessed by fluorescence polarization of two fluidity probes, 1,6-diphenyl-1,3,5-hexatriene (DPH) and a propionic acid derivative (DPH-PA), was also perturbed by the xenobiotic. Alterations on growth, oxygen consumption and physical properties of membrane lipids are stronger in B. stearothermophilus as compared to B. subtilis. A putative relationship between growth inhibition and respiratory activity impairment induced by TBT and its effects on the physical behaviour of bacterial membrane lipids is suggested.http://www.sciencedirect.com/science/article/B6TCP-4GSJR3R-9/1/18e0ee5c8ce4e887466d84b850ad8ec

Studies on the association of the Quercus suber decline disease with Phytophthora cinnamomi in Portugal

En Portugal, la enfermedad de la “seca” se ha descrito en los Quercus de hoja perenne (Quercus suber L. and Q.ilex subsp. rotundifolia Lam.) desde el final del siglo XIX. La mortalidad de estas especies afecta, particularmente las regiones centrales y meridionales del país, siendo uno de los problemas forestales más graves. Phytophthora cinnamomi Rands es el principal patógeno responsable de la mortalidad de alcornoques y encinas en Portugal. Se han desarrollado varios estudios teniendo como objetivo una mejor comprensión del efecto de la acción de P. cinnamomi en el decaimiento de los Quercus. El actual trabajo describe resultados preliminares de algunos de estos estudios.___________________________________In Portugal, the decline disease has been described in evergreen oaks (Quercus suber L. and Q.ilex subsp. rotundifolia Lam.) since the end of the 19th century. The mortality of these species affects, particularly the central and southern regions of the country, being one of the most severe forest problems. Phytophthora cinnamomi Rands is the main pathogen responsible for the cork and holm oak mortality in Portugal. Several studies have been developed aiming at a better understanding of the effect of the P. cinnamomi action on the cork oak trees decline. The present work describes preliminary results of some of these studies

Toxicity of methoprene as assessed by the use of a model microorganism

Methoprene is an insect juvenile growth hormone mimic, commonly used as a pesticide. Although widely used for the control of several pests, toxic effects on organisms of different phyla have been reported. These events triggered studies to clarify the mechanisms of toxicity of this insecticide putatively involved in ecological issues. Here we show the effect of methoprene on the normal cell growth and viability of a strain of the thermophilic eubacterium Bacillus stearothermophilus, previously used as a model for toxicological evaluation of other environment pollutants. Respiration studies were also carried out attempting to identify a putative target for the cytotoxic action of methoprene. Cell growth was affected and a decrease of the number of viable cells was observed as a result of the addition of methoprene to the growth medium, an effect reverted by the presence of Ca2+. Methoprene also inhibited the redox flow of B. stearothermophilus protoplasts before the cytochrome oxidase segment, an effect further studied by individually assessing the enzymatic activities of the respiratory complexes. This study suggests that methoprene membrane interaction and perturbation of cell bioenergetics may underlie the mechanism of toxicity of this compound in non-target organisms.http://www.sciencedirect.com/science/article/B6TCP-4GSJXGW-4/1/788f9fd7d4f3a4f1ae5d498a5674dcc

Relative hydrophobicity of (PEG or Ucon)-salt ATPSs

Aqueous Two-Phase Systems (ATPSs) are biphasic systems composed mainly by water. ATPSs are obtained upon mixing of two aqueous solutions of certain polymers or a polymer and a salt (above certain critical conditions, e.g. concentration, temperature). These systems are commonly indicated for the extraction of biomolecules. In this work, the partition coefficients for a series of five dinitrophenylated amino-acids (ranging from glycine to amino-caprylic acid) were determined experimentally in five different polymer-salt ATPSs (polymers: PEG or Ucon; salts: Na2SO4, Li2SO4 or (NH4)2SO4) at 23ºC. Values of the free energy of transfer of a methylene group, ΔG(CH2), for the five ATPSs were obtained from the partition coefficients and compared with ΔG(CH2) previously obtained for PEG-Na2SO4 (Rodríguez et al., 2007). Ucon-salt ATPSs presented higher values of ΔG(CH2) than the corresponding PEG-salt systems, witch indicates that the Ucon-rich phase is more hydrophobic than the PEG-rich phase