No abstract

Congo red (CR) has been shown to inhibit the accumulation in scrapie‐infected cells of prion protein (PrP) in the abnormal protease‐resistant form (PrP‐res). However, it was not clear if this effect was due to a direct interaction of CR with either PrP‐res or its protease‐sensitive precursor (PrP‐sen) or to a less direct effect on living cells. Here we show that CR inhibits PrP‐res formation in a simple cell‐free reaction composed predominantly of purified PrP‐res and PrP‐sen. Structurally modified CR analogues were also compared in both the cell‐free conversion reaction and scrapie‐infected neuroblastoma cells. Methylation of the central phenyl groups at the 2,2′ positions diminished the inhibitory potency by ≥10‐fold. In contrast, there was little effect of 3,3′ methylation of the phenyls, deletion of one phenyl, or addition of an amido group between the phenyls. The relative activities of these compounds were well correlated in both cellular and acellular systems. Molecular modeling indicated that CR and 3,3′‐methyl‐CR have little rotational restriction about the biphenyl bond and can readily adopt a planar conformation, as can phenyl‐CR and amido‐CR. In contrast, 2,2′‐methyl‐CR is restricted to a nonplanar conformation of the biphenyl group. Thus, planarity and/or torsional mobility of the central phenyl rings of CR and its analogues is probably important for inhibition of PrP‐res formation. On the other hand, variations in the intersulfonate distance in these molecules had little effect on PrP‐res inhibition. These results indicated a high degree of structural specificity in the inhibition of PrP‐res formation by CR and related compounds.

We describe the design and execution of the BORTAS (Quantifying the impact of BOReal forest fires on Tropospheric oxidants over the Atlantic using Aircraft and Satellites) experiment, which has the overarching objective of understanding the chemical aging of air masses that contain the emission products from seasonal boreal wildfires and how these air masses subsequently impact downwind atmospheric composition. The central focus of the experiment was a two-week deployment of the UK BAe-146-301 Atmospheric Research Aircraft (ARA) over eastern Canada, based out of Halifax, Nova Scotia. Atmospheric ground-based and sonde measurements over Canada and the Azores associated with the planned July 2010 deployment of the ARA, which was postponed by 12 months due to UK-based flights related to the dispersal of material emitted by the Eyjafjallajökull volcano, went ahead and constituted phase A of the experiment. Phase B of BORTAS in July 2011 involved the same atmospheric measurements, but included the ARA, special satellite observations and a more comprehensive ground-based measurement suite. The high-frequency aircraft data provided a comprehensive chemical snapshot of pyrogenic plumes from wildfires, corresponding to photochemical (and physical) ages ranging from < 1 day to ~<45 sr 10 days, largely by virtue of widespread fires over Northwestern Ontario. Airborne measurements reported a large number of emitted gases including semi-volatile species, some of which have not been been previously reported in pyrogenic plumes, with the corresponding emission ratios agreeing with previous work for common gases. Analysis of the NO_y data shows evidence of net ozone production in pyrogenic plumes, controlled by aerosol abundance, which increases as a function of photochemical age. The coordinated ground-based and sonde data provided detailed but spatially limited information that put the aircraft data into context of the longer burning season in the boundary layer. Ground-based measurements of particulate matter smaller than 2.5 μm (PM_2.5) over Halifax show that forest fires can on an episodic basis represent a substantial contribution to total surface PM_2.5

Abstract. We present lower/middle tropospheric columnaveraged CH 4 mole fraction time series measured by nine globally distributed ground-based FTIR (Fourier transform infrared) remote sensing experiments of the Network for the Detection of Atmospheric Composition Change (NDACC). We show that these data are well representative of the tropospheric regional-scale CH 4 signal, largely independent of the local surface small-scale signals, and only weakly dependent on upper tropospheric/lower stratospheric (UTLS) CH 4 variations. In order to achieve the weak dependency on the UTLS, we use an a posteriori correction method. We estimate a typical precision for daily mean values of about 0.5 % and a systematic error of about 2.5 %. The theoretical assessments are complemented by an extensive empirical study. For this purpose, we use surface in situ CH 4 measurements made within the Global Atmosphere Watch (GAW) network and compare them to the remote sensing data. We briefly discuss different filter methods for removing the local small-scale signals from the surface in situ data sets in order to obtain the in situ regional-scale signals. We find good agreement between the filtered in situ and the remote sensing data. The agreement is consistent for a variety of timescales that are interesting for CH 4 source/sink research: day-to-day, monthly, and inter-annual. The comparison study confirms our theoretical estimations and proves that the NDACC FTIR measurements can provide valuable data for investigating the cycle of CH 4 .Published by Copernicus Publications on behalf of the European Geosciences Union. E. Sepúlveda et al.: NDACC FTIR and GAW surface in situ tropospheric CH 4