Magnetic Absorption of Hard X-rays: New Aspects

The study of magnetic XANES of circularly polarized hard x-rays at the K-edges of 3d- and at the L-edges in 4f- and 5d-elements in ferro(i)magnetic materials is a powerful method to study in an element-selective manner magnetic aspects of the electronic structure of solids. It is demonstrated on the basis of simplified single-particle band-structure pictures that for the 5d-elements polarized by 3d- neighbors, information on the local spin and orbital moments can be directly deduced from the magnetic L2,3-spectra. Although the interpretation of the corresponding data of the rare earth is much more complicated interesting insights in the variation of their magnetic moment in different chemical environments and the binding character are possible as shown for Tb/Fe multilayered sample. The first observation of temperature-dependent changes of the magnetic absorption profile in invar alloys in comparison with theoretical calculations probe the applicability of magnetic K-edge spectroscopy on spin-fluctuating systems

The Helicobacter pylori CrdRS Two-Component Regulation System (HP1364/HP1365) Is Required for Copper-Mediated Induction of the Copper Resistance Determinant CrdA

Here we describe that the Helicobacter pylori sensor kinase produced by HP1364 and the response regulator produced by HP1365 and designated CrdS and CrdR, respectively, are both required for transcriptional induction of the H. pylori copper resistance determinant CrdA by copper ions. CrdRS-deficient mutants lacked copper induction of crdA expression and were copper sensitive. A direct role of CrdR in transcriptional regulation of crdA was confirmed by in vitro binding of CrdR to the crdA upstream region. A 21-nucleotide sequence located near the crdA promoter was shown to be required for CrdR binding

Validation of a novel, fully integrated and flexible microarray benchtop facility for gene expression profiling

Here we describe a novel microarray platform that integrates all functions needed to perform any array-based experiment in a compact instrument on the researcher’s laboratory benchtop. Oligonucle otide probes are synthesized in situ via a light- activated process within the channels of a three-dimensional microfluidic reaction carrier. Arrays can be designed and produced within hours according to the user’s requirements. They are processed in a fully automatic workflow. We have characterized this new platform with regard to dynamic range, discrimination power, reproducibility and accuracy of biological results. The instrument detects sample RNAs present at a frequency of 1:100 000. Detection is quantitative over more than two orders of magnitude. Experiments on four identical arrays with 6398 features each revealed a mean coefficient of variation (CV) value of 0.09 for the 6398 unprocessed raw intensities indicating high reproducibility. In a more elaborate experiment targeting 1125 yeast genes from an unbiased selection, a mean CV of 0.11 on the fold change level was found. Analyzing the transcriptional response of yeast to osmotic shock, we found that biological data acquired on our platform are in good agreement with data from Affymetrix GeneChips, quantitative real-time PCR and—albeit somewhat less clearly—to data from spotted cDNA arrays obtained from the literature