188 research outputs found

    Microsatellites for the Amazonian Fish Hypophthalmus marginatus

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    We isolated 41 and characterized 17 microsatellite loci for evaluating the genetic structure of the Amazonian fish Hypophthalmus marginatus, from the Tocantins and Araguaia River in the Eastern Amazonia. Of the 17 selected microsatellite sequences, 15 were dinucleotide repeats, 9 of which were perfect (5–31 repetitions) and 6 were composite motifs. Among these 17 microsatellites, only two were polymorphic. The average number of alleles (Na) observed in the five examined populations ranged from 3.5 to 4.5, while the average observed heterozygosity (Ho) ranged from 0.3 to 0.6. The allelic frequency was less homogeneous at the locus Hm 5 than that for the Hm 13. Genetic diversity was measured in three upstream and two downstream populations under the influence of the Tucuruí Hydroelectric Dam. Our findings provide evidence for low levels of genetic diversity in H. marginatus of the Tocantis basin possibility related to the Dam construction. The Fst and Rst analysis fits well with migratory characteristics of H. marginatus, suggesting the existence of a gene flow mainly in the upstream or downstream directions. To test the hypothesis that the Dam was responsible for the detected reduction on this species genetic diversity, a large number of genetic markers are recommended, covering geographic distribution range of the fish species

    Cymbopogon citratus EO antimicrobial activity against multi-drug resistant Gram-positive strains and non-albicans-Candida species

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    We studied the antibacterial and antifungal activity of Cymbopogon citratus. These properties were studied on hospital isolated multidrug resistant strains Staphylococcus aureus, Staphylococcus aureus, Staphylococcus epidermidis, Escherichia coli, Klebsiella pneumonia and their respective ATCC control strains. Pathogenic Candida albicans, Candida parapsilosis, and Candida tropicalis were also tested. Results of the present investigation provide evidence that the EO of Cymbopogon citratus could have a potential application in the treatment and prevention of diseases caused by Staphylococcus aureus methicillin-resistant strains and by vancomicin-resistant Staphylococcus epidermidis. Cymbopogon citratus EO is also effective against Candida albicans as well as the emerging Candida parapsilosis and Candida tropicalis pointing to its usefulness as an antifungal agent.info:eu-repo/semantics/publishedVersio

    Rapid and reliable identification of intact Candida clinical isolates using MALDI-TOF ICMS

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    The significant increase in the frequency of candidiasis wide world has promoted the study and development of fast and reliable techniques aimed at the replacement of traditional methods used for identification and typing of Candida clinical isolates. Matrix Assisted Laser Desorption/Ionisation Time-Of-Flight lntact Cell Mass Spectrometry (MALDI-TOF ICMS) has been applied as current method for Candida identification in clinical laboratories. This method is reported as suitable fur routine identification in clinical laboratories and fast and reliable for identification of pathogenic yeasts. The main aim of this study was to compare MALDI-TOF ICMS performance with the classical phenotypic approach and molecular analyses to identify Candida species from clinical cases. Forty clinical Candida isolates preserved in URM Culture Collection fur I to 52 years were identified by morphological and biochemical analysis as Candida albicans (20), C. krusei (05), C. parapsilosis (11) and C. tropicalis (04). These identifications were compared with the discriminative capability of the new phenotypic approaches using MALDI-TOF ICMS. MALDI-TOF ICMS data demonstrated 15% discordance when compared with morphological and biochemical analyses. The discordant isolates were analysed by ITS sequencing which corroborated the MALDI-TOF ICMS identifications. Five Candida krusei isolates were renamed Issatchenkia orientalis by MALDI-TOF ICMS SARAMISTM database, which is their teleomorphic name. ln conclusion MALDI-TOF ICMS represents a rapid and reliable method of identifying Candida and also presents clear benefits when compared with the performance of existing daily routine methods applied at health centres and hospitals. Research leading to these results received funding from the European Community's Seventh Framework Program (FP7, 2007-2013), Research lnfrastructures Action, under grant agreement No. FP7-228310 (EMbaRC project). Thanks are also due to Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES, Brazil) for funding support.European Community's Seventh Fmmework Progmm (FP7, 2007-2013), Research lnfrastructures Action, under gmnt agreement No. FP7-228310 (EMbaRC project), Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES, Brazil

    Time-of-flight and activation experiments on 147Pm and 171Tm for astrophysics

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    The neutron capture cross section of several key unstable isotopes acting as branching points in the s-process are crucial for stellar nucleosynthesis studies, but they are very challenging to measure due to the difficult production of sufficient sample material, the high activity of the resulting samples, and the actual (n,γ) measurement, for which high neutron fluxes and effective background rejection capabilities are required. As part of a new program to measure some of these important branching points, radioactive targets of 147Pm and 171Tm have been produced by irradiation of stable isotopes at the ILL high flux reactor. Neutron capture on 146Nd and 170Er at the reactor was followed by beta decay and the resulting matrix was purified via radiochemical separation at PSI. The radioactive targets have been used for time-of-flight measurements at the CERN n-TOF facility using the 19 and 185 m beam lines during 2014 and 2015. The capture cascades were detected using a set of four C6D6 scintillators, allowing to observe the associated neutron capture resonances. The results presented in this work are the first ever determination of the resonance capture cross section of 147Pm and 171Tm. Activation experiments on the same 147Pm and 171Tm targets with a high-intensity 30 keV quasi-Maxwellian flux of neutrons will be performed using the SARAF accelerator and the Liquid-Lithium Target (LiLiT) in order to extract the corresponding Maxwellian Average Cross Section (MACS). The status of these experiments and preliminary results will be presented and discussed as well

    Characterization of the n-TOF EAR-2 neutron beam

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    The experimental area 2 (EAR-2) at CERNs neutron time-of-flight facility (n-TOF), which is operational since 2014, is designed and built as a short-distance complement to the experimental area 1 (EAR-1). The Parallel Plate Avalanche Counter (PPAC) monitor experiment was performed to characterize the beam prole and the shape of the neutron 'ux at EAR-2. The prompt γ-flash which is used for calibrating the time-of-flight at EAR-1 is not seen by PPAC at EAR-2, shedding light on the physical origin of this γ-flash

    New measurement of the 242Pu(n,γ) cross section at n-TOF-EAR1 for MOX fuels : Preliminary results in the RRR

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    The spent fuel of current nuclear reactors contains fissile plutonium isotopes that can be combined with 238U to make mixed oxide (MOX) fuel. In this way the Pu from spent fuel is used in a new reactor cycle, contributing to the long-term sustainability of nuclear energy. The use of MOX fuels in thermal and fast reactors requires accurate capture and fission cross sections. For the particular case of 242Pu, the previous neutron capture cross section measurements were made in the 70's, providing an uncertainty of about 35% in the keV region. In this context, the Nuclear Energy Agency recommends in its "High Priority Request List" and its report WPEC-26 that the capture cross section of 242Pu should be measured with an accuracy of at least 7-12% in the neutron energy range between 500 eV and 500 keV. This work presents a brief description of the measurement performed at n-TOF-EAR1, the data reduction process and the first ToF capture measurement on this isotope in the last 40 years, providing preliminary individual resonance parameters beyond the current energy limits in the evaluations, as well as a preliminary set of average resonance parameters
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