Sea bass (Dicentrarchus labrax) : a model organism for assessing multi-level responses to estrogenic chemicals in marine surface waters

Resumo apresentado sob poster ao 5th International Symposium of Fish Endocrinology, CAstellon, Spain, Setember 5-9, 2004.There is growing concern that aquatic wildlife in surface waters of the European Union is exposed to natural and man-made chemicals that have the ability to mimic estrogens and lead to reproductive dysfunction. Estrogenic responses in fish are the net result of complex chains of events involving the uptake, distribution and metabolism of test agents until they interact with their target sites. Typically these aspects cannot be modelled in short-term cell-based assays, only studies with vertebrates offer the opportunity to assess potential interactions of test compounds at higher organisational levels. The most widely studied biological response in fish to environmental estrogens is the production of vitellogenin (Vtg). However, few studies have attempted to link this endpoint with effects on xenobiotic biotransformation enzymes and genotoxic responses. This work is part of a study focusing on the combination effects of mixtures of estrogenic chemicals in marine and freshwater organisms. As test organism the sea bass (Dicentrarchus labrax) was selected, a common species in European marine systems. Juveniles were exposed under a flow-through system for 14 days to the natural estrogen 17ß-estradiol and ethynylestradiol. Actual chemical concentrations in the water-column were determined by gas chromatography with ion trap detection. Effects at subcellular level were analysed using Vtg as a reference endpoint [1]. Its relevance is evaluated by further investigations on liver 7-ethoxyresorufin-O-deethylase (EROD) activity and erythrocytic nuclear abnormalities [2]. These measurements were integrated with organism level endpoints (i.e. condition factor, hepatossomatic index) to provide evidence for cause-effect of estrogenic contamination. The general suitability of the sea bass as a model organism for the screening of estrogenic chemicals in the marine environment is discussed.Comissão Europeia (CE) - ACE, EVK1-CT-2001-100

Improved conditions for the aerobic reductive decolourisation of azo dyes by Candida zeylanoides

A number of anaerobic and aerobic bacterial species are known to decolourise azo dyes through the reduction of the azo bonds, forming the corresponding amines. In this work, we describe improved decolourisation conditions for model azo dyes by the ascomycete yeast Candida zeylanoides. The dyes were derived from the diazonium salts of metanilic and sulfanilic acids and N,N-dimethylaniline or 2-naphthol as coupling components. Total decolourisation times observed in culture media supplemented with 0.2mM dye ranged from 40 go 60 hours. The initial decolourisation rates were 14-52µmol.(g dry cell)-¹.h-¹, depending on dye structure. In the course of decolourisation either metanilic acid or sulfanilic acid were detected in the supernatant fluid, showing that decolourization by this yeast strain is due to azo bond reduction. None of those aminobenzenesulphonates supported microorganism growth as carbon and energy source but both could be used, to a limited extent, as nitrogen sources. The azo reductase activity is not significantly affected by pre-adaptation of the microorganism to the dyes.Junta Nacional de Investigação Científica e Tecnológica - PraxisXXI/2/2.2/QUI/44/94. Erasmus programme

Sea bass (Dicentrarchus labrax) : a model organism for the screening of estrogenic chemicals in marine surface waters?

Society of Environmental Toxicology and Chemistry - SETAC Europe 14th Annual Meeting, Prague, Czech Republic, April 2004.There is growing concern that aquatic wildlife in surface waters of the European Union is exposed to natural and man-made chemicals that have the ability to mimic estrogens and lead to reproductive dysfunction. Estrogenic responses in fish are the net result of complex chains of events involving the uptake, distribution and metabolism of test agents until they interact with their target sites. Typically these aspects cannot be modelled in short-term cell-based assays, only studies with vertebrates offer the opportunity to assess potential interactions of test compounds at higher organisational levels. However, studies with endocrine disrupting chemicals have been performed mainly with freshwater organisms. The sensitivity of a marine fish species to different estrogenic chemicals was investigated under chronic exposure conditions. This work is part of a study focusing on the combination effects of mixtures of estrogenic chemicals in marine and freshwater organisms (ACE, EVK1-CT-2001-100). As test organism the sea bass (Dicentrarchus labrax) was selected, a common species in European marine systems. Juveniles were exposed under a flow-through system for 14 days for a set of reference chemicals (17Ã -estradiol, ethynylestradiol, nonylphenol, octylphenol, bisphenol A). Effects at subcellular level were analysed using vitellogenesis as endpoint. Its relevance is evaluated by further investigations about the individual fitness (condition factor, hepatossomatic index), as well as the liver cytochrome P450 activity. The general suitability of the sea bass as a model organism for the screening of estrogenic chemicals in the marine environment is discussed.Comissãoo Europeia (CE) - ACE, EVK1-CT-2001-100

Modelling of a radio frequency plasma bridge neutralizer (RFPBN)

A performance model of a radio frequency plasma bridge neutralizer was developed to calculate the electrical parameters and optimize the neutralizer design. Minimization of power losses and gas consumption, and a maximization of the neutralizer lifetime and the reliability of the system are requirements of all electric propulsion concepts and strongly determine their future application. The requirements of the neutralizer depend on mission profiles

First Permian occurrence of the shark egg capsule morphotype Palaeoxyris Brongniart, 1828

© 2016, © by the Society of Vertebrate Paleontology.Citation for this article: Abu Hamad, A., J. Fischer, S. Voigt, H. Kerp, J. W. Schneider, and F. Scholze. 2016. First Permian occurrence of the shark egg capsule morphotype Palaeoxyris Brongniart, 1828. Journal of Vertebrate Paleontology. DOI: 10.1080/02724634.2016.1112290

advanced electric propulsion diagnostic tools at iom

Abstract Recently, we have set up an Advanced Electric Propulsion Diagnostic (AEPD) platform [1] , which allows for the in-situ measurement of a comprehensive set of thruster performance parameters. The platform utilizes a five-axis-movement system for precise positioning of the thruster with respect to the diagnostic heads. In the first setup (AEPD1) an energy-selective mass spectrometer (ESMS) and a miniaturized Faraday probe for ion beam characterization, a telemicroscope and a triangular laser head for measuring the erosion of mechanical parts, and a pyrometer for surface temperature measurements were integrated. The capabilities of the AEPD1 platform were demonstrated with two electric propulsion thrusters, a gridded ion thruster RIT 22 (Airbus Defence & Space, Germany, [13]) and a Hall effect thruster SPT 100D EM1 (EDB Fakel, Russia, [1] , [4] ), in two different vacuum facilities

Modelling line edge roughness in periodic line-space structures by Fourier optics to improve scatterometry

In the present paper, we propose a 2D-Fourier transform method as a simple and efficient algorithm for stochastical and numerical studies to investigate the systematic impacts of line edge roughness on light diffraction pattern of periodic line-space structures. The key concept is the generation of ensembles of rough apertures composed of many slits, to calculate the irradiance of the illuminated rough apertures far away from the aperture plane, and a comparison of their light intensities to those of the undisturbed, ’non-rough’ aperture. We apply the Fraunhofer approximation and interpret the rough apertures as binary 2D-gratings to compute their diffraction patterns very efficiently as the 2D-Fourier transform of the light distribution of the source plane. The rough edges of the aperture slits are generated by means of power spectrum density (PSD) functions, which are often used in metrology of rough geometries. The mean efficiencies of the rough apertures reveal a systematic exponential decrease for higher diffraction orders if compared to the diffraction pattern of the unperturbed aperture. This confirms former results, obtained by rigorous calculations with computational expensive finite element methods (FEM) for a simplified roughness model. The implicated model extension for scatterometry by an exponential damping factor for the calculated efficiencies allows to determine the standard deviation σ_r of line edge roughness along with the critical dimensions (CDs), i.e., line widths, heights and other profile properties in the sub-micrometer range. First comparisons with the corresponding roughness value determined by 3D atomic force microscopy (3D AFM) reveal encouraging results

Transgenic Expression of the Anti-parasitic Factor TEP1 in the Malaria Mosquito Anopheles gambiae

Mosquitoes genetically engineered to be resistant to Plasmodium parasites represent a promising novel approach in the fight against malaria. The insect immune system itself is a source of anti-parasitic genes potentially exploitable for transgenic designs. The Anopheles gambiae thioester containing protein 1 (TEP1) is a potent anti-parasitic protein. TEP1 is secreted and circulates in the mosquito hemolymph, where its activated cleaved form binds and eliminates malaria parasites. Here we investigated whether TEP1 can be used to create malaria resistant mosquitoes. Using a GFP reporter transgene, we determined that the fat body is the main site of TEP1 expression. We generated transgenic mosquitoes that express TEP1r, a potent refractory allele of TEP1, in the fat body and examined the activity of the transgenic protein in wild-type or TEP1 mutant genetic backgrounds. Transgenic TEP1r rescued loss-of-function mutations, but did not increase parasite resistance in the presence of a wild-type susceptible allele. Consistent with previous reports, TEP1 protein expressed from the transgene in the fat body was taken up by hemocytes upon a challenge with injected bacteria. Furthermore, although maturation of transgenic TEP1 into the cleaved form was impaired in one of the TEP1 mutant lines, it was still sufficient to reduce parasite numbers and induce parasite melanization. We also report here the first use of Transcription Activator Like Effectors (TALEs) in Anopheles gambiae to stimulate expression of endogenous TEP1. We found that artificial elevation of TEP1 expression remains moderate in vivo and that enhancement of endogenous TEP1 expression did not result in increased resistance to Plasmodium. Taken together, our results reveal the difficulty of artificially influencing TEP1-mediated Plasmodium resistance, and contribute to further our understanding of the molecular mechanisms underlying mosquito resistance to Plasmodium parasites

The ACE Project: a synopsis of in vivo studies to predict estrogenic mixture effects in freshwater and marine fish

Society of Environmental Toxicology and Chemistry - SETAC Europe 15th Annual Meeting, Lille, France, May 2005.This work is part of the ACE project (ACE, EVK1-CT-2001-100) which aim is to investigate multi-component mixtures of estrogenic compounds in aquatic ecosystems. Here we present a synopsis of in vivo data related with the joint estrogenic action of five estrogenic compounds (17ß-estradiol, ethynylestradiol, nonylphenol, octylphenol and bisphenol-A) on vitellogenesis in fathead minnow (Pimephales promelas) and sea bass (Dicentrarchus labrax). The studies were conducted with freshwater adult males and marine juveniles under flow through exposure conditions for two weeks. In the first step, fish were exposed to the five compounds individually in order to generate concentration- response curves. Therefore mixture effects were predicted on the basis of the potency of each compound by using the model of concentration addition (CA). Finally, the compounds were tested as a mixture at equipotent concentrations, and the observed mixture effects were compared to the predictions. The mixture studies showed an good agreement between observed and predicted effects and provided evidence that CA can be used as a predictive tool for the effect assessment of mixtures of (xeno)estrogens in freshwater or marine ecosystems. The differences/limitations of running in vivo mixture studies with freshwater and marine species will be discussed.Comissão Europeia (CE) - ACE project - ACE, EVK1-CT-2001-100