The SAXS/WAXS beamline at the Australian Synchrotron is an advanced and flexible undulator X‐ray scattering beamline used for small‐ and wide‐angle X‐ray scattering analysis on a wide variety of solids, fluids and surfaces across a diverse range of research and development fields. The beamline has numerous features that minimize the intensity of the instrument background, provide automated stable optics, and allow accurate analysis of very weakly scattering samples. The geometric and intensity requirements of a three‐slit collimation system are described in detail for conventional metal and single‐crystal germanium slits. Straightforward ray tracing and simple linear projections describe the observed direct beam as well as parasitic background scattering geometry of the beamline at its longest camera length, providing a methodology for the design and operation of similar beamlines. As an aid to instrument design, the limit of background intensity determined by the intensity incident on single‐crystal germanium guard slit edges and its q dependence was quantified at 11 keV. Details of the beamline's implementation, underlying optical concept and measured performance are given.
MX1 is a bending-magnet crystallography beamline at the 3 GeV Australian Synchrotron. The beamline delivers hard X-rays in the energy range from 8 to 18 keV to a focal spot at the sample position of 120 mm FWHM. The beamline endstation and ancillary equipment facilitate local and remote access for both chemical and biological macromolecular crystallography. Here, the design of the beamline and endstation are discussed. The beamline has enjoyed a full user program for the last seven years and scientific highlights from the user program are also presented.
Viruses that establish latent infections have evolved unique mechanisms to avoid host immune recognition. Maintenance proteins of these viruses regulate their synthesis to levels sufficient for maintaining persistent infection but below threshold levels for host immune detection. The mechanisms governing this finely tuned regulation of viral latency are unknown. Here we show that mRNAs encoding gammaherpesviral maintenance proteins contain within their open reading frames clusters of unusual structural elements, G-quadruplexes, which are responsible for the cisacting regulation of viral mRNA translation. By studying the Epstein-Barr virus-encoded nuclear antigen 1 (EBNA1) mRNA, we demonstrate that destabilization of G-quadruplexes using antisense oligonucleotides increases EBNA1 mRNA translation. In contrast, pretreatment with a G-quadruplex-stabilizing small molecule, pyridostatin, decreases EBNA1 synthesis, highlighting the importance of G-quadruplexes within virally encoded transcripts as unique regulatory signals
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