7,653 research outputs found

    The effect of LEDs on biomass and phycobiliproteins production in thermotolerant oscillatoria sp

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    Featured Application: The selection of LEDs wavelength, intensity, and light: Dark cycle positively enhances the biomass production and phycocyanin synthesis in Oscillatoria sp. This study evaluates the role of different LED lights (white, blue/red), intensity (”mol m−2 s−1), and photoperiod in the production of biomass and phycocyanin-C, allophycocyanin and phycoerythrin (C-PC, APC, and PE respectively) from a novel thermotolerant strain of Oscillatoria sp. Results show that a mixture of white with blue/red LEDs can effectively double the biomass concentration up to 1.3 g/L, while the concentration of the selected phycobiliproteins increased proportionally to biomass. Results also indicate that high light intensities (>120 ”mol m−2 s−1) can diminish the final concentration of C-PC, APC, and PE, significantly reducing the overall biomass produced. Finally, the photoperiod analysis showed that longer light exposure times (18:6 h) improved both biomass and phycobiliproteins concentration. These results demonstrate that the application of LEDs to produce a novel strain of Oscillatoria sp can double the biomass concentration, and the photoperiod regulation can eventually enhance the final concentration of specific phycobiliproteins such as APC and PE

    Microplate technique to determine hemolytic activity for routine typing of Listeria strains

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    Because the hemolysis produced by Listeria monocytogenes and Listeria seeligeri on blood agar is frequently difficult to interpret, we developed a microplate technique for the routine determination of hemolytic activity with erythrocyte suspensions. This microtechnique is a simple and reliable test for distinguishing clearly between hemolytic and nonhemolytic strains and could be used instead of the CAMP (Christie-Atkins-Munch-Petersen) test with Staphylococcus aureus in the routine typing of Listeria strains. Furthermore, our results suggest that the quantitation of the hemolytic activity of the Listeria strains, along with the D-xylose, L-rhamnose, and alpha-methyl-D-mannoside acidification tests, allows the differentiation of L. monocytogenes, L. seeligeri, and Listeria ivanovii. We also observed that the treatment of erythrocytes with crude exosubstances of rhodococcus equi, Pseudomonas fluorescens, Acinetobacter calcoaceticus, and S. aureus enhanced the hemolytic activity of all Listeria strains with this characteristic

    P-tau235: a novel biomarker for staging preclinical Alzheimer's disease

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    Alzheimer’s disease (AD) is characterised by a long preclinical phase. Although phosphorylated tau (p-tau) species such as p-tau217 and p-tau231 provide accurate detection of early pathological changes, other biomarkers capable of staging disease progression during preclinical AD are still needed. Combining exploratory and targeted mass spectrometry methods in neuropathologically confirmed brain tissue, we observed that p-tau235 is a prominent feature of AD pathology. In addition, p-tau235 seemed to be preceded by p-tau231, in what appeared to be a sequential phosphorylation event. To exploit its biomarker potential in cerebrospinal fluid (CSF), we developed and validated a new p-tau235 Simoa assay. Using three clinical cohorts, we demonstrated that (i) CSF p-235 increases early in AD continuum, and (ii) changes in CSF p-tau235 and p-tau231 levels during preclinical AD are consistent with the sequential phosphorylation evidence in AD brain. In conclusion, CSF p-tau235 appears to be not only a highly specific biomarker of AD but also a promising staging biomarker for the preclinical phase. Thus, it could prove useful tracking disease progression and help enriching clinical trial recruitment

    Genes of the antioxidant system of the honey bee: annotation and phylogeny

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    Antioxidant enzymes perform a variety of vital functions including the reduction of life-shortening oxidative damage. We used the honey bee genome sequence to identify the major components of the honey bee antioxidant system. A comparative analysis of honey bee with Drosophila melanogaster and Anopheles gambiae shows that although the basic components of the antioxidant system are conserved, there are important species differences in the number of paralogs. These include the duplication of thioredoxin reductase and the expansion of the thioredoxin family in fly; lack of expansion of the Theta, Delta and Omega GST classes in bee and no expansion of the Sigma class in dipteran species. The differential expansion of antioxidant gene families among honey bees and dipteran species might reflect the marked differences in life history and ecological niches between social and solitary species

    Calibration of the Logarithmic-Periodic Dipole Antenna (LPDA) Radio Stations at the Pierre Auger Observatory using an Octocopter

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    An in-situ calibration of a logarithmic periodic dipole antenna with a frequency coverage of 30 MHz to 80 MHz is performed. Such antennas are part of a radio station system used for detection of cosmic ray induced air showers at the Engineering Radio Array of the Pierre Auger Observatory, the so-called Auger Engineering Radio Array (AERA). The directional and frequency characteristics of the broadband antenna are investigated using a remotely piloted aircraft (RPA) carrying a small transmitting antenna. The antenna sensitivity is described by the vector effective length relating the measured voltage with the electric-field components perpendicular to the incoming signal direction. The horizontal and meridional components are determined with an overall uncertainty of 7.4^{+0.9}_{-0.3} % and 10.3^{+2.8}_{-1.7} % respectively. The measurement is used to correct a simulated response of the frequency and directional response of the antenna. In addition, the influence of the ground conductivity and permittivity on the antenna response is simulated. Both have a negligible influence given the ground conditions measured at the detector site. The overall uncertainties of the vector effective length components result in an uncertainty of 8.8^{+2.1}_{-1.3} % in the square root of the energy fluence for incoming signal directions with zenith angles smaller than 60{\deg}.Comment: Published version. Updated online abstract only. Manuscript is unchanged with respect to v2. 39 pages, 15 figures, 2 table

    Multi-resolution anisotropy studies of ultrahigh-energy cosmic rays detected at the Pierre Auger Observatory

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    We report a multi-resolution search for anisotropies in the arrival directions of cosmic rays detected at the Pierre Auger Observatory with local zenith angles up to 80∘80^\circ and energies in excess of 4 EeV (4×10184 \times 10^{18} eV). This search is conducted by measuring the angular power spectrum and performing a needlet wavelet analysis in two independent energy ranges. Both analyses are complementary since the angular power spectrum achieves a better performance in identifying large-scale patterns while the needlet wavelet analysis, considering the parameters used in this work, presents a higher efficiency in detecting smaller-scale anisotropies, potentially providing directional information on any observed anisotropies. No deviation from isotropy is observed on any angular scale in the energy range between 4 and 8 EeV. Above 8 EeV, an indication for a dipole moment is captured; while no other deviation from isotropy is observed for moments beyond the dipole one. The corresponding pp-values obtained after accounting for searches blindly performed at several angular scales, are 1.3×10−51.3 \times 10^{-5} in the case of the angular power spectrum, and 2.5×10−32.5 \times 10^{-3} in the case of the needlet analysis. While these results are consistent with previous reports making use of the same data set, they provide extensions of the previous works through the thorough scans of the angular scales.Comment: Published version. Added journal reference and DOI. Added Report Numbe
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