Nuclear-encoded splicing factors for yeast mitochondrial introns

textHypothesized to be ancestors of eukaryotic spliceosomal introns, extant group II introns are found in bacteria, archaea, and in the mitochondria and chloroplast genomes of some eukaryotes. While some of these catalytic intron RNAs encode an intron-encoded maturase to assist in their splicing, not all do, eliciting the question of how these introns are spliced out. Two such introns are the mitochondrial introns aI5 [gamma] and bI1 of Saccharomyces cerevisiae. Previous in vitro studies on the self-splicing activity of these introns revealed requirements for non-physiologically high salt concentration and temperature for catalytic activity, suggesting a dependence upon proteins in vivo. With most mitochondrial proteins known to be encoded by the nucleus, it seems likely that some exist to assist, either directly or indirectly, in the correct splicing of these introns. Previous searches for such proteins relied on a combination of two genetic screens: looking for a mutant's inability to grow on the non-fermentable carbon source glycerol-(Gly⁻ phenotype)- in the presence of a given intron, and a Gly⁺ phenotype in the intron's absence. In contrast, this study employs Northern hybridization to identify splicing defects in a series of mutants constructed by targeted gene deletion, allowing for identification of proteins required for splicing that would not have been otherwise detectable. In order to identify associated proteins, this method is complemented by Tandem Affinity Purification of Mss116, the DEAD-box RNA chaperone required for splicing of all the yeast mitochondrial introns. In addition to Mss116, special attention was given to the insertase Oxa1, found to be required for aI5 [gamma] and bI1splicing specifically; and to Mne1, found to be required for splicing group I intron aI5 [beta]. The results point to distinctly different auxiliary protein requirements for group I introns, group II introns that encode their own maturases, and group II introns that do not encode maturases. My findings are consistent with the possibility that the splicing of aI5 [gamma] and bI1, group II introns that do not encode maturases, is coordinated by multiple proteins comprising a splicing complex situated at the surface of the mitochondrial inner membrane in close association with the mitoribosomes.Cellular and Molecular Biolog

Measurement of quarkonium production cross sections in pp collisions at s=\sqrt{s}= 13 TeV

Differential production cross sections of prompt J/ψ and ψ(2S) charmonium and ϒ(nS) ( n=1,2,3 ) bottomonium states are measured in proton–proton collisions at s=13TeV , with data collected by the CMS detector at the LHC, corresponding to an integrated luminosity of 2.3 fb$^{−1}$ for the J/ψ and 2.7 fb$^{−1}$ for the other mesons. The five quarkonium states are reconstructed in the dimuon decay channel, for dimuon rapidity |y|<1.2 . The double-differential cross sections for each state are measured as a function of y and transverse momentum, and compared to theoretical expectations. In addition, ratios are presented of cross sections for prompt ψ(2S) to J/ψ , ϒ(2S) to ϒ(1S) , and ϒ(3S) to ϒ(1S) production

Search for supersymmetry with photons in pp collisions at s\sqrt s = 8 TeV

Two searches for physics beyond the standard model in events containing photons are presented. The data sample used corresponds to an integrated luminosity of 19.7 inverse femtobarns of proton-proton collisions at $\sqrt{s}$ = 8 TeV, collected with the CMS experiment at the CERN LHC. The analyses pursue different inclusive search strategies. One analysis requires at least one photon, at least two jets, and a large amount of transverse momentum imbalance, while the other selects events with at least two photons and at least one jet, and uses the razor variables to search for signal events. The background expected from standard model processes is evaluated mainly from data. The results are interpreted in the context of general gauge-mediated supersymmetry, with the next-to-lightest supersymmetric particle either a bino- or wino-like neutralino, and within simplified model scenarios. Upper limits at 95% confidence level are obtained for cross sections as functions of the masses of the intermediate supersymmetric particles