492 research outputs found

    Expression and functional analysis of TaASY1 during meiosis of bread wheat (Triticum aestivum)

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    Background: Pairing and synapsis of homologous chromosomes is required for normal chromosome segregation and the exchange of genetic material via recombination during meiosis. Synapsis is complete at pachytene following the formation of a tri-partite proteinaceous structure known as the synaptonemal complex (SC). In yeast, HOP1 is essential for formation of the SC, and localises along chromosome axes during prophase I. Homologues in Arabidopsis (AtASY1), Brassica (BoASY1) and rice (OsPAIR2) have been isolated through analysis of mutants that display decreased fertility due to severely reduced synapsis of homologous chromosomes. Analysis of these genes has indicated that they play a similar role to HOP1 in pairing and formation of the SC through localisation to axial/lateral elements of the SC. Results: The full length wheat cDNA and genomic clone, TaASY1, has been isolated, sequenced and characterised. TaASY1 is located on chromosome Group 5 and the open reading frame displays significant nucleotide sequence identity to OsPAIR2 (84%) and AtASY1 (63%). Transcript and protein analysis showed that expression is largely restricted to meiotic tissue, with elevated levels during the stages of prophase I when pairing and synapsis of homologous chromosomes occur. Immunolocalisation using transmission electron microscopy showed TaASY1 interacts with chromatin that is associated with both axial elements before SC formation as well as lateral elements of formed SCs. Conclusion: TaASY1 is a homologue of ScHOP1, AtASY1 and OsPAIR2 and is the first gene to be isolated from bread wheat that is involved in pairing and synapsis of homologous chromosomes.Scott A Boden, Nadim Shadiac, Elise J Tucker, Peter Langridge and Jason A Abl

    Towards laser driven table-top coherent diffractive X-ray microscopy of cultured hippocampal neurons

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    Neurodegenerative diseases such as Alzheimer’s disease have a huge impact on the world population; over 44 million people worldwide and 850,000 in the UK were recorded as living with dementia in 2013. There are numerous theories attempting to explain the cause of Alzheimer’s disease. Histology from the brains of people who had Alzheimer’s disease shows neurofibilliary tangles and amyloid plaques. Their role in the mechanism of disease is not yet completely understood but we envisage that novel imaging techniques may aid understanding. We present initial data collected using confocal fluorescence microscopy and hard X-ray scanning diffractive microscopy (ptychography) on cultured neuron samples plus high resolution large field of view imaging of test samples from a soft X-ray lab based high harmonic generation (HHG) source

    LEG- AND JOINT STIFFNESS IN MALE ELITE HIGH JUMP: THE INFLUENCE OF STIFFNESS ON SPORTS PERFORMANCE

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    The purpose of this study was to analyse stiffness in the mechanical system of the world’s elite high jumpers. Seven male elite high jump athletes (personal best 2.24 m ± 0.06 m) were filmed with 19 Infrared-High-Speed-Cameras during jumping. Kinetics were captured with a force plate. It was found that a different leg and joint stiffness during takeoff enables nearly the same jumping height. For example, a typical power jumper with a leg stiffness of 543.6 N m-1 kg-1 reached 2.13 m, while a typical speed jumper with a leg stiffness of 1133.5 N m-1 kg-1 reached a comparable height of 2.12 m. Therefore, it seems that sports performance in single leg jumping is not limited by athlete’s leg and joint stiffness in a small group of male elite high jumpers

    Ptychographic coherent diffractive imaging with orthogonal probe relaxation

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    Ptychography is a scanning coherent diffractive imaging (CDI) technique that relies upon a high level of stability of the illumination during the course of an experiment. This is particularly an issue for coherent short wavelength sources, where the beam intensity is usually tightly focused on the sample in order to maximize the photon flux density on the illuminated region of the sample and thus a small change in the beam position results in a significant change in illumination of the sample. We present an improved ptychographic method that allows for limited stability of the illumination wavefront and thus significantly improve the reconstruction quality without additional prior knowledge. We have tested our reconstruction method in a proof of concept experiment, where the beam instability of a visible light source was emulated using a piezo driven mirror, and also in a short wavelength microscopy CDI setup using a high harmonic generation source in the extreme ultraviolet range. Our work shows a natural extension of the ptychography method that paves the way to use ptychographic imaging with any limited pointing stability coherent source such as free electron or soft X-ray lasers and improve reconstruction quality of long duration synchrotron experiments

    What happens when international migrants settle? Ethnic group population trends and projections for uk local areas

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    Research findings report of WHAT HAPPENS WHEN INTERNATIONAL MIGRANTS SETTLE? ETHNIC GROUP POPULATION TRENDS AND PROJECTIONS FOR UK LOCAL AREAS project. A project in the ESRC Understanding Population Trends and Processes Programme, maintained by the ReStore repository and archived to NCRM Eprints 2022

    Astrometry with the Keck-Interferometer: the ASTRA project and its science

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    The sensitivity and astrometry upgrade ASTRA of the Keck Interferometer is introduced. After a brief overview of the underlying interferometric principles, the technology and concepts of the upgrade are presented. The interferometric dual-field technology of ASTRA will provide the KI with the means to observe two objects simultaneously, and measure the distance between them with a precision eventually better than 100 uas. This astrometric functionality of ASTRA will add a unique observing tool to fields of astrophysical research as diverse as exo-planetary kinematics, binary astrometry, and the investigation of stars accelerated by the massive black hole in the center of the Milky Way as discussed in this contribution.Comment: 22 pages, 10 figures (low resolution), contribution to the summerschool "Astrometry and Imaging with the Very Large Telescope Interferometer", 2 - 13 June, 2008, Keszthely, Hungary, corrected authorlis
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