Genome-Wide Identification of Calcium-Response Factor (CaRF) Binding Sites Predicts a Role in Regulation of Neuronal Signaling Pathways

Calcium-Response Factor (CaRF) was first identified as a transcription factor based on its affinity for a neuronal-selective calcium-response element (CaRE1) in the gene encoding Brain-Derived Neurotrophic Factor (BDNF). However, because CaRF shares no homology with other transcription factors, its properties and gene targets have remained unknown. Here we show that the DNA binding domain of CaRF has been highly conserved across evolution and that CaRF binds DNA directly in a sequence-specific manner in the absence of other eukaryotic cofactors. Using a binding site selection screen we identify a high-affinity consensus CaRF response element (cCaRE) that shares significant homology with the CaRE1 element of Bdnf. In a genome-wide chromatin immunoprecipitation analysis (ChIP-Seq), we identified 176 sites of CaRF-specific binding (peaks) in neuronal genomic DNA. 128 of these peaks are within 10kB of an annotated gene, and 60 are within 1kB of an annotated transcriptional start site. At least 138 of the CaRF peaks contain a common 10-bp motif with strong statistical similarity to the cCaRE, and we provide evidence predicting that CaRF can bind independently to at least 64.5% of these motifs in vitro. Analysis of this set of putative CaRF targets suggests the enrichment of genes that regulate intracellular signaling cascades. Finally we demonstrate that expression of a subset of these target genes is altered in the cortex of Carf knockout (KO) mice. Together these data strongly support the characterization of CaRF as a unique transcription factor and provide the first insight into the program of CaRF-regulated transcription in neurons

In-situ radiography of a split-Hopkinson bar dynamically loaded materials

This paper presents a description and the demonstration results of a custom-designed bespoke Split-Hopkinson Pressure Bar (SHBP) which has been installed at the ID-19 beamline at the European Synchrotron Radiation Facility (ESRF). Building upon recent advances in real-time x-ray imaging, this system enables the study of dynamic mechanical phenomena through ultra-high-speed x-ray phase-contrast radiographs captured every 528 ns with high spatial-temporal resolution. By adding synchronized strain gauges measurements in the same experiment, bulk stress-strain behaviour can be correlated to the local processes underlying deformation, damage and failure. This article briefly outlines the newly installed hardware and its design. Demonstration experiments showing damage development in dynamically loaded Ti-6Al-4V and concrete are presented to underline the potential of an SHBP to be used in combination with synchrotron-based high-speed hard x-ray imaging

In-situ radiography of a split-Hopkinson bar dynamically loaded materials

This paper presents a description and the demonstration results of a custom-designed bespoke Split-Hopkinson Pressure Bar (SHBP) which has been installed at the ID-19 beamline at the European Synchrotron Radiation Facility (ESRF). Building upon recent advances in real-time x-ray imaging, this system enables the study of dynamic mechanical phenomena through ultra-high-speed x-ray phase-contrast radiographs captured every 528 ns with high spatial-temporal resolution. By adding synchronized strain gauges measurements in the same experiment, bulk stress-strain behaviour can be correlated to the local processes underlying deformation, damage and failure. This article briefly outlines the newly installed hardware and its design. Demonstration experiments showing damage development in dynamically loaded Ti-6Al-4V and concrete are presented to underline the potential of an SHBP to be used in combination with synchrotron-based high-speed hard x-ray imaging