Low energy electron energy-loss spectroscopy of CF₃X (X=Cl,Br)

We report threshold electron energy-loss spectra for the fluorohalomethanes CFC₃X (X=Cl,Br). Measurements were made at incident electron energies of 30 and 100 eV in energy-loss range of 4-14 eV, and at scattering angles of 4 degrees and 15 degrees. Several new electronic transitions are observed which are ascribable to excitation of low-lying states as well as are intrinsically overlapped in the molecules themselves. Assignments of these electronic transitions are suggested. These assignments are based on present spectroscopic and cross-section measurements, high-energy scattering spectra, and ab initio molecular orbital calculations. The calculated potential curves along the C-X bond show repulsive nature, suggesting that these transitions may lead to dissociation of the C-X bond. The present results are also compared with the previous ones for CF₃H, CF₄, and CF₃I.This work was performed with the support and under the auspices of the CUP, the IAEA’s Co-ordinated Research Program, MEXT, and JAEA. One of the authors C.M. had been also thankful to the Japan Society for Promotion of Science for financial support under Grant No. P04064. One of the authors L.P. also acknowledges partial support by the Academic Frontier Program of MEXT. One of the authors H.C. acknowledges the support from the Korea Research Foundation 2006-311-C00031

The N-Terminus of GalE Induces tmRNA Activity in Escherichia coli

BACKGROUND: The tmRNA quality control system recognizes stalled translation complexes and facilitates ribosome recycling in a process termed 'ribosome rescue'. During ribosome rescue, nascent chains are tagged with the tmRNA-encoded SsrA peptide, which targets tagged proteins for degradation. In Escherichia coli, tmRNA rescues ribosomes arrested on truncated messages, as well as ribosomes that are paused during elongation and termination. METHODOLOGY/PRINCIPAL FINDINGS: Here, we describe a new translational pausing determinant that leads to SsrA peptide tagging of the E. coli GalE protein (UDP-galactose 4-epimerase). GalE chains are tagged at more than 150 sites, primarily within distinct clusters throughout the C-terminal domain. These tagging sites do not correspond to rare codon clusters and synonymous recoding of the galE gene had little effect on tagging. Moreover, tagging was largely unaffected by perturbations that either stabilize or destabilize the galE transcript. Examination of GalE-thioredoxin (TrxA) fusion proteins showed that the GalE C-terminal domain is no longer tagged when fused to an N-terminal TrxA domain. Conversely, the N-terminus of GalE induced tagging within the fused C-terminal TrxA domain. CONCLUSIONS/SIGNIFICANCE: These findings suggest that translation of the GalE N-terminus induces subsequent tagging of the C-terminal domain. We propose that co-translational maturation of the GalE N-terminal domain influences ribosome pausing and subsequent tmRNA activity

No evidence for the association of DRD4 with ADHD in a Taiwanese population within-family study

BACKGROUND: Attention Deficit Hyperactivity Disorder (ADHD) is a prevalent and highly heritable childhood disorder. The dopamine D4 receptor (DRD4) gene has shown a genetic association with ADHD in Caucasian populations with meta-analysis indicating a small but significant effect across datasets. It remains uncertain whether this association can be generalised to non-Caucasian ethnic groups. Here we investigate two markers within the DRD4 gene in a Taiwanese population, the exon 3 variable number tandem repeat (VNTR) and a 5' 120 base-pair duplication. METHODS: Within-family transmission disequilibrium tests of association of the 5' 120 base-pair duplication, and exon 3 VNTR in a Taiwanese population. RESULTS: No evidence of association of ADHD with either polymorphism in this population was observed. CONCLUSION: The DRD4 gene markers investigated were not found to be associated with ADHD in this Taiwanese sample. Further work in Taiwanese and other Asian populations will therefore be required to establish whether the reports of association of DRD4 genetic variants in Caucasian samples can be generalised to Asian populations

Low-energy electron impact elastic and inelastic scattering from CF₃I

Absolute differential cross sections for elastic scattering from CF3I are reported between 1.5 and 60 eV and over scattering angles of 20°–130°. Vibrational excitation cross sections for the composite stretching modes are shown to be preferentially enhanced at incident electron energies between 5 and 9 eV indicating the formation of short-lived shape resonances