In vivo biotinylated calpastatin improves the affinity purification of human m-calpain

Recently we established a novel affinity purification method for calpain by exploiting the specific and reversible binding properties of its intrinsically disordered protein inhibitor, calpastatin. The immobilization strategy relied on the strength and specificity of the biotin - streptavidin interaction. Here, we report an improved and optimized method that even enables the general applicability of in vivo biotinylated (intrinsically disordered) proteins in any affinity capture strategy. Since in vitro chemical biotinylation is only accomplished with reagents that lack exact site specificity, it can not only cause sample heterogeneity but it can also hamper the functionality of the biotinylated molecules. Therefore, we have developed a recombinant expression protocol to produce in vivo biotinylated human calpastatin domain 1 (hCSD1) in Escherichia coli. We have experimentally verified that the biotinylated polypeptide tag is compatible with the intrinsically disordered state of hCSD1 and that it does not influence the functional properties of this intrinsically disordered protein (IDP). The in vivo biotinylated hCSD1 was then used without the need of any prepurification step prior to the affinity capturing of its substrate, human m-calpain. This leads to a simplified purification strategy that allows capturing the calpain efficiently from a complex biological mixture with only a single chromatogaphic step and in a considerably reduced timeframe. Our approach is generally applicable through the in vivo biotinylation of any IDP of interest, and its practical implementation will showcase the power to exploit the properties of IDPs in affinity capture strategies. © 2018 The Author

Risk Factors for Arthralgias or Myalgias Associated with Quinupristin‐Dalfopristin Therapy

Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/90134/1/phco.23.2.159.32078.pd

Opgraving aan de Cottalaan (Tongeren). Onderzoek van enkele laat- Romeinse graven. Eindverslag van een toevalsvondst.

Na het volledig uitgraven van een bouwput voor een kelder werden archeologische sporen gemeld. Het onderzoek heeft in totaal 19 sporen opgeleverd. 18 hiervan zijn antropogeen en worden gedateerd in de Romeinse tijd. Eén hiervan is natuurlijk. Deze 18 antropogene sporen bestaan uit drie grachten, twee inhumatiegraven, zes kuilen en zeven sporen in de putwand. Het gegeven dat de bouwput reeds volledig was uitgegraven tot een zeer diep niveau, heeft er in geresulteerd dat nog maar een zeer beperkt aantal sporen aangetroffen werd. Alle sporen blijken ook nog maar ondiep te zijn. Desondanks is er toch sprake van enige kenniswinst. In het zuidoostelijk deel van de opgraving zijn twee grafstructuren herkendbeide tekenden zich nog duidelijk af in de natuurlijke ondergrond. Het gaat om rechthoekige grafkuilen, die nog skeletresten bevatten. De graven hebben globaal een noord-zuid oriëntatie. Slechts één van de twee overleden individuen heeft grafgiften meegekregen. Tijdens het onderzoek zijn vijf kuilen herkend. Het onderzoek heeft enkele grachtfragmenten opgeleverd. Niet alle fragmenten zijn even eenduidig te interpreteren. Gracht 1 is de meest duidelijke en kan doorheen de hele bouwput gevolgd worden(33,15 m lang en 3,83 m breed). De andere fragmenten zijn echter minder duidelijk, waarbij één zelfs nog uitsluitend in het noordelijke putprofiel herkend kon worden

Formation of hydrogen peroxide and water from the reaction of cold hydrogen atoms with solid oxygen at 10K

The reactions of cold H atoms with solid O2 molecules were investigated at 10 K. The formation of H2O2 and H2O has been confirmed by in-situ infrared spectroscopy. We found that the reaction proceeds very efficiently and obtained the effective reaction rates. This is the first clear experimental evidence of the formation of water molecules under conditions mimicking those found in cold interstellar molecular clouds. Based on the experimental results, we discuss the reaction mechanism and astrophysical implications.Comment: 12 pages, 3 Postscript figures, use package amsmath, amssymb, graphic

Constraints on the H2O formation mechanism in the wind of carbon-rich AGB stars

Context. The recent detection of warm H$_2$O vapor emission from the outflows of carbon-rich asymptotic giant branch (AGB) stars challenges the current understanding of circumstellar chemistry. Two mechanisms have been invoked to explain warm H$_2$O vapor formation. In the first, periodic shocks passing through the medium immediately above the stellar surface lead to H$_2$O formation. In the second, penetration of ultraviolet interstellar radiation through a clumpy circumstellar medium leads to the formation of H$_2$O molecules in the intermediate wind. Aims. We aim to determine the properties of H$_2$O emission for a sample of 18 carbon-rich AGB stars and subsequently constrain which of the above mechanisms provides the most likely warm H$_2$O formation pathway. Methods, Results, and Conclusions. See paper

The enigmatic nature of the circumstellar envelope and bow shock surrounding Betelgeuse as revealed by Herschel. I. Evidence of clumps, multiple arcs, and a linear bar-like structure

Context. The interaction between stellar winds and the interstellar medium (ISM) can create complex bow shocks. The photometers on board the Herschel Space Observatory are ideally suited to studying the morphologies of these bow shocks. Aims. We aim to study the circumstellar environment and wind-ISM interaction of the nearest red supergiant, Betelgeuse. Methods. Herschel PACS images at 70, 100, and 160 micron and SPIRE images at 250, 350, and 500 micron were obtained by scanning the region around Betelgeuse. These data were complemented with ultraviolet GALEX data, near-infrared WISE data, and radio 21 cm GALFA-HI data. The observational properties of the bow shock structure were deduced from the data and compared with hydrodynamical simulations. Results. The infrared Herschel images of the environment around Betelgeuse are spectacular, showing the occurrence of multiple arcs at 6-7 arcmin from the central target and the presence of a linear bar at 9 arcmin. Remarkably, no large-scale instabilities are seen in the outer arcs and linear bar. The dust temperature in the outer arcs varies between 40 and 140 K, with the linear bar having the same colour temperature as the arcs. The inner envelope shows clear evidence of a non-homogeneous clumpy structure (beyond 15 arcsec), probably related to the giant convection cells of the outer atmosphere. The non-homogeneous distribution of the material even persists until the collision with the ISM. A strong variation in brightness of the inner clumps at a radius of 2 arcmin suggests a drastic change in mean gas and dust density some 32 000 yr ago. Using hydrodynamical simulations, we try to explain the observed morphology of the bow shock around Betelgeuse. Conclusions: [abbreviated]Comment: 26 page

Characterizing Exoplanets in the Visible and Infrared: A Spectrometer Concept for the EChO Space Mission

Transit-spectroscopy of exoplanets is one of the key observational techniques to characterize the extrasolar planet and its atmosphere. The observational challenges of these measurements require dedicated instrumentation and only the space environment allows an undisturbed access to earth-like atmospheric features such as water or carbon-dioxide. Therefore, several exoplanet-specific space missions are currently being studied. One of them is EChO, the Exoplanet Characterization Observatory, which is part of ESA's Cosmic Vision 2015-2025 program, and which is one of four candidates for the M3 launch slot in 2024. In this paper we present the results of our assessment study of the EChO spectrometer, the only science instrument onboard this spacecraft. The instrument is a multi-channel all-reflective dispersive spectrometer, covering the wavelength range from 400 nm to 16 microns simultaneously with a moderately low spectral resolution. We illustrate how the key technical challenge of the EChO mission - the high photometric stability - influences the choice of spectrometer concept and drives fundamentally the instrument design. First performance evaluations underline the fitness of the elaborated design solution for the needs of the EChO mission.Comment: 20 pages, 8 figures, accepted for publication in the Journal of Astronomical Instrumentatio

Water, hydrogen cyanide, carbon monoxide, and dust production from distant comet 29P/Schwassmann-Wachmann 1

peer reviewedContext. 29P/Schwassmann-Wachmann 1 is a distant Centaur/comet, showing persistent CO-driven activity and frequent outbursts. Aims: We aim to better characterize its gas and dust activity from multiwavelength observations performed during outbursting and quiescent states. Methods: We used the HIFI, PACS and SPIRE instruments of the Herschel space observatory on several dates in 2010, 2011, and 2013 to observe the H2O 557 GHz and NH3 573 GHz lines and to image the dust coma in the far-infrared. Observations with the IRAM 30 m telescope were undertaken in 2007, 2010, 2011, and 2021 to monitor the CO production rate through the 230 GHz line, and to search for HCN at 89 GHz. The 70 and 160 µm PACS images were used to measure the thermal flux from the nucleus and the dust coma. Modeling was performed to constrain the size of the sublimating icy grains and to derive the dust production rate. Results: HCN is detected for the first time in comet 29P (at 5σ in the line area). H2O is detected as well, but not NH3. H2O and HCN line shapes differ strongly from the CO line shape, indicating that these two species are released from icy grains. CO production rates are in the range (2.9-5.6) × 10E28 s−1 (1400-2600 kg s−1). A correlation between the CO production rate and coma brightness is observed, as is a correlation between CO and H2O production. The correlation obtained between the excess of CO production and excess of dust brightness with respect to the quiescent state is similar to that established for the continuous activity of comet Hale-Bopp. The measured Q(H2O)/Q(CO) and Q(HCN)/Q(CO) production rate ratios are 10.0 ± 1.5 % and 0.12 ± 0.03 %, respectively, averaging the April-May 2010 measurements (Q(H2O) = (4.1 ± 0.6) × 10E27 s−1, Q(HCN) = (4.8 ± 1.1) × 10E25 s−1). We derive three independent and similar values of the effective radius of the nucleus, ~31 ± 3 km, suggesting an approximately spherical shape. The inferred dust mass-loss rates during quiescent phases are in the range 30-120 kg s−1, indicating a dust-to-gas mass ratio <0.1 during quiescent activity. We conclude that strong local heterogeneities exist on the surface of 29P, with quenched dust activity from most of the surface, but not in outbursting regions. Conclusions: The volatile composition of the atmosphere of 29P strongly differs from that of comets observed within 3 au from the Sun. The observed correlation between CO, H2O and dust activity may provide important constraints for the outburst-triggering mechanism