Lead induces oxidative stress and apoptotic response in Saccharomyces cerevisiae

Background: Heavy metals are found in the environment mainly due to anthropogenic activities. The presence of metals in surface waters and soils can create an environmental hazard and pose a serious risk to public health. Lead is a non essential metal for biological functions, displays a toxic effect and is classified as probable human carcinogen. Objectives: In the present work, the mode of cell death induced by Pb in Saccharomyces cerevisiae was studied. Methods: Cell proliferation capacity was evaluated by colony-forming units counting. Membrane integrity was assessed by the fluorescent probes bis(1,3-dibutylbarbituric acid trimethine oxonol) [DiBAC4(3)] and propidium iodide. Reactive oxygen species (ROS) accumulation was examined by using 2,7-dichlorodihydrofluorescein diacetate (H2DCFDA). Nuclear morphological modifications were revealed by diaminophenylindole (DAPI) staining. Conclusions: Yeast cells, Pb-exposed, up to 6 hours, lost progressively the capacity to proliferate and maintained the membrane integrity. The exposition of yeast cells to Pb resulted in the intracellular accumulation of ROS. The addition of ascorbic acid (a ROS scavenger) strongly reduced the oxidative stress and impaired the loss of proliferation capacity in Pbtreated cells. Pb-induced death is an active process, which requires the participation of cellular metabolism, since the simultaneous addition of cycloheximide attenuated the loss of cell proliferation capacity. Pb-exposed cells displayed nuclear morphological alterations, like chromatin fragmentation. Together, the obtained data indicate that exposition of yeast cells to 1 mmol/l Pb results in a severe oxidative stress, which can be the trigger of programmed cell death by apoptosis

Retinal Vessel Segmentation Using the 2-D Morlet Wavelet and Supervised Classification

We present a method for automated segmentation of the vasculature in retinal images. The method produces segmentations by classifying each image pixel as vessel or non-vessel, based on the pixel's feature vector. Feature vectors are composed of the pixel's intensity and continuous two-dimensional Morlet wavelet transform responses taken at multiple scales. The Morlet wavelet is capable of tuning to specific frequencies, thus allowing noise filtering and vessel enhancement in a single step. We use a Bayesian classifier with class-conditional probability density functions (likelihoods) described as Gaussian mixtures, yielding a fast classification, while being able to model complex decision surfaces and compare its performance with the linear minimum squared error classifier. The probability distributions are estimated based on a training set of labeled pixels obtained from manual segmentations. The method's performance is evaluated on publicly available DRIVE and STARE databases of manually labeled non-mydriatic images. On the DRIVE database, it achieves an area under the receiver operating characteristic (ROC) curve of 0.9598, being slightly superior than that presented by the method of Staal et al.Comment: 9 pages, 7 figures and 1 table. Accepted for publication in IEEE Trans Med Imag; added copyright notic

The mathematical description of the electrosynthesis of composites of oxy-hydroxycompounds cobalt with polypyrrole overooxidazed

The electrosynthesis of the composite with of the overoxidized polypyrrole with cobalt oxy-hydroxide in strongly acidic media has been described mathematically, using linear stability theory and bifurcation analysis. The steadystates stability conditions and oscillatory and monotonic instability requirements have been described too. The system´s behavior was compared with behavior of other systems with overoxidation, electropolymerization of heterocyclic compounds and electrosynthesis of the cobalt oxy-hydroxides

Mapeamento da cobertura vegetal e uso da terra na bacia hidrográfica do rio Teles Pires.

O objetivo do trabalho é efetuar o mapeamento da cobertura vegetal e uso da terra na bacia hidrográfica Teles Pires para o ano 2003. A bacia localiza-se entre os biomas Amazônia e Cerrado, nos estados de Mato Grosso e Pará, entre as seguintes coordenadas: 58° 40'S - 53º 15' S e 7° 15' W - 15° 30' W. Inicialmente foi necessário efetuar o download das imagens de satélite da série Landsat 5, sensor TM correspondentes ao ano de 2003

Parâmetros reprodutivos de rebanho caprino no Sertão Pernambucano.

O presente estudo teve como objetivo avaliar os parâmetros reprodutivos de rebanho caprino e os pesos ao nascimento das crias em sistema de produção no Sertão Pernambucano. Foram utilizadas 83 cabras divididas em dois grupos (G1 n=41 e G2 n=42), mantendo cada grupo em área de Caatinga de 40,5 ha durante o período chuvoso e em 13 ha de capim-bufel (Cenchrus ciliaris L.), na época seca. A estação de monta teve duração de 60 dias entre os meses de fevereiro a abril de 2012. As variáveis mensuradas foram: taxa de parição (fêmeas paridas / fêmeas expostas x 100), taxa de concepção (fêmeas cobertas / fêmeas expostas x 100), taxa de fertilidade (fêmeas paridas / fêmeas cobertas x 100), prolificidade (crias nascidas / fêmeas paridas), taxa de mortalidade (crias mortas / crias nascidas x 100), além dos pesos das crias, em relação ao sexo e ordem de parto das matrizes. Foram obtidos 52 partos, 24 no G1 e 28 no G2. O rebanho apresentou valores médios de 62,6% de taxa de parição, 73,6% de taxa de concepção, 85,2% de taxa de fertilidade, além de 1,53 crias nascidas por matriz parida e 10% de taxa mortalidade das crias de 1 a 90 dias. Os pesos ao nascimento foram em média 1,98 kg (2,20 kg para os machos e 1,84 para fêmeas). Os animais nascidos de fêmeas pluríparas apresentaram 2,05 kg, enquanto os filhos das primíparas tiveram 1,76 kg. Em geral, os parâmetros reprodutivos do rebanho e os pesos ao nascer das crias foram satisfatórios, considerando o sistema produtivo, obtendo-se valores superiores aos observados no sistema de criação extensivo tradicional

Uniformidade de distribuicao de agua na superficie e no perfil do solo, irrigado com o microaspersor Rain-Bird QN-14.

Foi avaliado, em condições, o Co eficiente de Uniformidade de Christiansen (CUC) das lâminas de água aplicadas na superfície e distribuídas no perfil do solo, nas profundidade de 0-0,20; 0,20-0,40 e 0,40-0,60 m tendo sido obtido, os coeficientes de 42,61; 64,90; 79,04 e 84,06 %, respectivamente. Observou-se também que o Coeficiente de Uniformidade de Christiansen (CUC) da redistribuição d a lâmina de água no perfil do solo aumentou com a profundidade d as camadas

Traffic differentiation support in vehicular delay-tolerant networks

Vehicular Delay-Tolerant Networking (VDTN) is a Delay-Tolerant Network (DTN) based architecture concept for transit networks, where vehicles movement and their bundle relaying service is opportunistically exploited to enable non-real time applications, under environments prone to connectivity disruptions, network partitions and potentially long delays. In VDTNs, network resources may be limited, for instance due to physical constraints of the network nodes. In order to be able to prioritize applications traffic according to its requirements in such constrained scenarios, traffic differentiation mechanisms must be introduced at the VDTN architecture. This work considers a priority classes of service (CoS) model and investigates how different buffer management strategies can be combined with drop and scheduling policies, to provide strict priority based services, or to provide custom allocation of network resources. The efficiency and tradeoffs of these proposals is evaluated through extensive simulation.Part of this work has been supported by Instituto de Telecomunicações, Next Generation Networks and Applications Group (NetGNA), Portugal, in the framework of the Project VDTN@Lab, and by the Euro-NF Network of Excellence of the Seventh Framework Programme of EU