Structural and functional characterization of interactions involving the Tfb1 subunit of TFIIH and the NER factor Rad2

The general transcription factor IIH (TFIIH) plays crucial roles in transcription as part of the pre-initiation complex (PIC) and in DNA repair as part of the nucleotide excision repair (NER) machinery. During NER, TFIIH recruits the 3′-endonuclease Rad2 to damaged DNA. In this manuscript, we functionally and structurally characterized the interaction between the Tfb1 subunit of TFIIH and Rad2. We show that deletion of either the PH domain of Tfb1 (Tfb1PH) or several segments of the Rad2 spacer region yield yeast with enhanced sensitivity to UV irradiation. Isothermal titration calorimetry studies demonstrate that two acidic segments of the Rad2 spacer bind to Tfb1PH with nanomolar affinity. Structure determination of a Rad2–Tfb1PH complex indicates that Rad2 binds to TFIIH using a similar motif as TFIIEα uses to bind TFIIH in the PIC. Together, these results provide a mechanistic bridge between the role of TFIIH in transcription and DNA repair

Multiple-frequency bioimpedance devices for fluid management in people with chronic kidney disease receiving dialysis : a systematic review and economic evaluation

The National Institute for Health Research Health Technology Assessment programme. Acknowledgements The authors are grateful to Lara Kemp for her secretarial support. The authors would also like to thank the members of the specialist committee assembled to support this assessment: Dr Andrew Davenport (Royal Free Hospital, London), Dr Simon Roe (Nottingham University Hospitals NHS Trust), Dr Elizabeth Lindley (St James’s University Hospital), Dr Wesley Hayes (Great Ormond Street Hospital), Ms Joanne Prince (Central Manchester University Hospitals NHS Foundation Trust), Mr Nick McAleer (Royal Devon & Exeter NHS Foundation Trust), Dr Kay Tyerman (Leeds General Infirmary), Dr Graham Woodrow (St James’s University Hospital) and Mr Paul Taylor (lay specialist committee member). The Health Services Research Unit, Health Economics Research Unit and Institute of Applied Health Sciences, University of Aberdeen are all core funded by the Chief Scientist Office of the Scottish Government Health DirectoratesPeer reviewedPublisher PD

Bidirectional Reflectance Distribution Function (BRDF) of Deep Convective Clouds (DCC) Derived from PARASOL Measurements and Compared to Radiative Transfer Computation and Model

PARASOL is a satellite which provided multidirectional and polarized observation of the Earth reflectances for the visible and near infrared spectral range for nearly 9-years, from 2005 to 2013. A rich archive of top-of-atmosphere reflectances have been collected over deep convective clouds (DCC) according a devoted data selection. This selection is able to guarantee observation very suitable for calibration purpose as well as a consistent time series (regarding morphology, geometry, radiometry). These selection criteria are described in Fougnie and Bach (IEEE, 2009). DCC are used for a long while for calibration purposes. First, they were used for interband calibration in the visible range (e.g. for POLDER and Végétation sensors). DCC were very powerful for an accurate monitoring or validation of the sensor degradation with time (e.g. PARASOL, MERIS). DCC were also used to derive the sensor degradation within the entire field-of-view (e.g. PARASOL). Finally, DCC are intensively used for cross-calibration of LEO and GEO sensors in the GSICS framework. It is known that DCC are very white targets (or with minor variations with respect to the white behaviour) on the visible and near infrared spectral domain. They are also characterized by a moderate bidirectional signature. PARASOL data collected over the entire archive were used to derive the bidirectional function (BRDF) of the DCC reflectance. For every spectral band, all acquisitions (more than 1 million) were assumed to be generated by the same “mean” cloud. Five ranges of 10° solar zenith angles were built, and on which acquisitions were geometrically binned into 2°x2° boxes in viewing zenith and relative azimuth angles. Results for 490, 670 and 865 will be presented. BRDF effects are found to be very similar for the visible range, about 15%, and are a little bite smaller for the near infrared band, about 10%. It appears that the most isotropic part of the BRDF corresponds to the backscattering geometries. Computation using radiative transfer code based on discrete ordinate (Lafrance et al., IEEE, 2002) were built. The top of DCC were described as pure hexagonal crystals (PHM), but also Inhomogeneous Hexagonal Monocrystals (RHM). Top of atmosphere reflectances were generated for all geometries and for visible to near infrared bands. Comparison with PARASOL observation, and highlighting a good agreement, will be presented. Finally, results will be confronted to the directional model from Hu et al. (2004) used as reference in the framework of GSICS for intercalibration of sensors. The general conclusion will try to recommend geometries for which the cross-calibration will be optimized in term of uncertainties

Suspended bacterial biomass and activity in full-scale drinking water distribution systems: impact of water treatment

Bacterial regrowth in drinking water distribution systems is a source of concern since it could result in non-compliance with water quality regulations, taste and odor problems, and may be associated with an increased risk of gastrointestinal illnesses. Bacterial regrowth is dependent on several factors, including the amount of substrate available for growth, such as biodegradable dissolved organic carbon (BDOC), oxidant residuals and the presence of corrosion. To investigate the impact of nutrients levels and oxidant residual maintenance, a full-scale investigation of two distribution systems was completed. This study presents data obtained from two distribution systems (DS) fed by different treatment trains: one DS has low BDOC concentrations and no free oxidant residual (St. Rose plant, Quebec, Canada), and the other has a high BDOC concentration and moderate concentrations of free oxidant residual (Pont Viau plant, Quebec, Canada). Monitoring included heterotrophic plate counts (HPC), total direct count by epifluorescence after acridine orange staining (AODC), direct viable counts (DVC-CTC method) and the measurement of bacterial production by 3H-thymidine incorporation. Results show that bacterial biomass (AODC and DVC) and bacterial production are lower in the DS fed by the treatment plant with a low BDOC concentration in the plant effluent. This difference is observed in warm water but not in cold water. The results suggest that HPCs are not a good indicator of bacterial regrowth in DSs. Finally, statistical analysis demonstrated that the treatment type and cumulative surface to volume ratio are the significant factors affecting regrowth in the distribution systems studied in warm waters.info:eu-repo/semantics/publishe

Structural and Biochemical Characterization of a Copper-Binding Mutant of the Organomercurial Lyase MerB: Insight into the Key Role of the Active Site Aspartic Acid in Hg–Carbon Bond Cleavage and Metal Binding Specificity

In bacterial resistance to mercury, the organomercurial lyase (MerB) plays a key role in the detoxification pathway through its ability to cleave Hg–carbon bonds. Two cysteines (C96 and C159; <i>Escherichia coli</i> MerB numbering) and an aspartic acid (D99) have been identified as the key catalytic residues, and these three residues are conserved in all but four known MerB variants, where the aspartic acid is replaced with a serine. To understand the role of the active site serine, we characterized the structure and metal binding properties of an <i>E. coli</i> MerB mutant with a serine substituted for D99 (MerB D99S) as well as one of the native MerB variants containing a serine residue in the active site (<i>Bacillus megaterium</i> MerB2). Surprisingly, the MerB D99S protein copurified with a bound metal that was determined to be Cu­(II) from UV–vis absorption, inductively coupled plasma mass spectrometry, nuclear magnetic resonance, and electron paramagnetic resonance studies. X-ray structural studies revealed that the Cu­(II) is bound to the active site cysteine residues of MerB D99S, but that it is displaced following the addition of either an organomercurial substrate or an ionic mercury product. In contrast, the <i>B. megaterium</i> MerB2 protein does not copurify with copper, but the structure of the <i>B. megaterium</i> MerB2–Hg complex is highly similar to the structure of the MerB D99S–Hg complexes. These results demonstrate that the active site aspartic acid is crucial for both the enzymatic activity and metal binding specificity of MerB proteins and suggest a possible functional relationship between MerB and its only known structural homologue, the copper-binding protein NosL