A Genome-wide Drosophila Screen for Heat Nociception Identifies α2δ3 as an Evolutionarily Conserved Pain Gene

Worldwide, acute and chronic pain affects 20% of the adult population and represents an enormous financial and emotional burden. Using genome-wide neuronal-specific RNAi knock-down in Drosophila, we report a global screen for an innate behavior and identify hundreds of novel genes implicated in heat nociception, including the α2δ-family calcium channel subunit straightjacket (stj). Mice mutant for the stj ortholog CACNA2D3 (α2δ3) also exhibit impaired behavioral heat pain sensitivity. In addition, in humans, α2δ3 SNP variants associate with reduced sensitivity to acute noxious heat and chronic back pain. Functional imaging in α2δ3 mutant mice revealed impaired transmission of thermal pain evoked signals from the thalamus to higher order pain centers. Intriguingly, in α2δ3 mutant mice thermal pain and tactile stimulation triggered strong cross-activation or synesthesia of brain regions involved in vision, olfaction, and hearing

Structured Multilayer Electrodes without Nafion for Polymer Electrolyte Membrane Fuel Cells

The use of alternative support materials and special MEA preparation techniques allow a replacing of Nafion® within the electrode layer. A possible candidate for the replacement is the electron/proton conductive polymer polyaniline (PANI). This material has proven its suitability and stability as support in a fuel cell environment. The incorporation of Pt/single-walled carbon nanotubes (SWCNT) between the PANI layers can improve the electron conductivity of the system. The assembly is fabricated by the newly introduced spray coating technique, in which alternating layers of Pt/PANI or Ru/PANI, and Pt/SWCNT are sprayed directly onto a Nafion® membrane. 3D electrodes are obtained with an expected high porosity and enhanced noble metal utilization. The assembled multilayered electrodes were used at the anode side with a commercial Pt/CB-Nafion® catalyst layer at the cathode side in a real fuel cell test. The MEAs showed high Pt utilization values with an adequate power density

Structured multilayered electrodes of proton/electron conducting polymer for polymer electrolyte membrane fuel cells assembled by spray coating

Membrane electrode assemblies (MEAs) for fuel cell applications consist of electron conductive support materials, proton conductive ionomer, and precious metal nanoparticles to enhance the catalytic activity towards H2 oxidation and O2 reduction. An optimized connection of all three phases is required to obtain a high noble metal utilization, and accordingly a good performance. Using polyaniline (PANI) as an alternative support material, the generally used ionomer Nafion® could be replaced in the catalyst layer. PANI has the advantage to be electron and proton conductive at the same time, and can be used as a catalyst support as well. In this study, a new technique building up alternating layers of PANI supported catalyst and single-walled carbon nanotubes (SWCNT) supported catalyst is introduced. Multilayers of PANI and SWCNT catalysts are used on the cathode side, whereas the anode side is composed of commercial platinum/carbon black catalyst and Nafion®, applied by an airbrush. No additional Nafion® ionomer is used for proton conductivity of the cathode. The so called spray coating method results in high power densities up to 160 mW cm−2 with a Pt loading of 0.06 mg cm−2 at the cathode, yielding a Pt utilization of 2663 mW mgPt−1. As well as PANI, supports of SWCNTs have the advantage to have a fibrous structure and additional, they provide high electron conductivity. The combination of the new technique and the fibrous 1-dimensional support materials leads to a porous 3-dimensional electrode network which could enhance the gas transport through the electrode as well as the Pt utilization. The spray coating method could be upgraded to an in-line process and is not restricted to batch production

Alternative Support Materials for Fuel Cell Catalysts

One major issue still impeding the rapid market introduction of low-temperature polymer electrolyte membrane fuel cells (PEMFC) is the catalyst's poor long-term stability. In particular in the harsh conditions at the cathode side corrosion of the standard carbon support takes place, and high platinum loadings even speed up this process. Recent research focuses on novel, non-carbon support materials, using either electron-conductive oxides or conductive polymers. In this paper the synthesis and characterization of TiO2-supported Pt, niobium-doped TiO2-supported Pt, Sb-doped tin oxide as well as polyaniline-supported Pt as novel cathode catalysts for PEMFC are presented

Global analysis of the Staphylococcus aureus response to mupirocin

In the present study, we analyzed the response of S. aureus to mupirocin, the drug of choice for nasal decolonization. Mupirocin selectively inhibits the bacterial isoleucyl-tRNA synthetase (IleRS), leading to the accumulation of uncharged isoleucyl-tRNA and eventually the synthesis of (p)ppGpp. The alarmone (p)ppGpp induces the stringent response, an important global transcriptional and translational control mechanism that allows bacteria to adapt to nutritional deprivation. To identify proteins with an altered synthesis pattern in response to mupirocin treatment, we used the highly sensitive 2-dimensional gel electrophoresis technique in combination with mass spectrometry. The results were complemented by DNA microarray, Northern blot, and metabolome analyses. Whereas expression of genes involved in nucleotide biosynthesis, DNA metabolism, energy metabolism, and translation was significantly downregulated, expression of isoleucyl-tRNA synthetase, the branched-chain amino acid pathway, and genes with functions in oxidative-stress resistance (ahpC and katA) and putative roles in stress protection (the yvyD homologue SACOL0815 and SACOL1759 and SACOL2131) and transport processes was increased. A comparison of the regulated genes to known regulons suggests the involvement of the global regulators CodY and SigB in shaping the response of S. aureus to mupirocin. Of particular interest was the induced transcription of genes encoding virulence-associated regulators (i.e., arlRS, saeRS, sarA, sarR, sarS, and sigB), as well as genes directly involved in the virulence of S. aureus (i.e., fnbA, epiE, epiG, and seb)

A Point Mutation in the Sensor Histidine Kinase SaeS of Staphylococcus aureus Strain Newman Alters the Response to Biocide Exposure▿ †

Staphylococcus aureus reacts to changing environmental conditions such as heat, pH, and chemicals through global regulators such as the sae (S. aureus exoprotein expression) two-component signaling system. Subinhibitory concentrations of some antibiotics were shown to increase virulence factor expression. Here, we investigated the S. aureus stress response to sublethal concentrations of a commonly used biocide (Perform), by real-time quantitative PCR (qRT-PCR), promoter activity assay, sodium dodecyl sulfate (SDS)-polyacrylamide gel electrophoresis, and a flow cytometric invasion assay. Perform, acting through the production of reactive oxygen species, generally downregulated expression of extracellular proteins in strains 6850, COL, ISP479C but upregulated these proteins in strain Newman. Upregulated proteins were sae dependent. The Perform component SDS, but not paraquat (another oxygen donor), mimicked the biocide effect. Eap (extracellular adherence protein) was most prominently augmented. Upregulation of eap and sae was confirmed by qRT-PCR. Promoter activity of sae P1 was increased by Perform and SDS. Both substances enhanced cellular invasiveness, by 2.5-fold and 3.2-fold, respectively. Increased invasiveness was dependent on Eap and the sae system, whereas agr, sarA, sigB, and fibronectin-binding proteins had no major effect in strain Newman. This unique response pattern was due to a point mutation in SaeS (the sensor histidine kinase), as demonstrated by allele swapping. Newman saePQRSISP479C behaved like ISP479C, whereas saePQRSNewman rendered ISP479C equally responsive as Newman. Taken together, the findings indicate that a point mutation in SaeS of strain Newman was responsible for increased expression of Eap upon exposure to sublethal Perform and SDS concentrations, leading to increased Eap-dependent cellular invasiveness. This may be important for understanding the regulation of virulence in S. aureus