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Die Mitte der 1990er Jahre erfolgte Erfassung von Sedum villosum in Hessen wurde wiederholt. Die Vorkommen in der Rhön sind durch verringerte Weideintensität rückläufig. Ein Vorkommen ist hier offenbar erloschen. Das Vorkommen im Unteren Vogelsberg besteht weiterhin, obwohl die Standortbedingungen an einer Waldstraße ungünstig erscheinen. Das Vorkommen im Vorderen Vogelsberg ist erloschen. Ein zwischenzeitlich entdecktes Vorkommen in der Westhessischen Senke bei Alsfeld auf einem Basaltweg ist stabil; allerdings ist die Zukunftsprognose für dieses Vorkommen auf Grund von Brache negativ. Über die ersten Erfahrungen bei der Wiederansiedlung aus einer Erhaltungskultur wird berichtet.
Introns of human transfer RNA precursors (pre-tRNAs) are excised by the tRNA splicing endonuclease TSEN in complex with the RNA kinase CLP1. Mutations in TSEN/CLP1 occur in patients with pontocerebellar hypoplasia (PCH), however, their role in the disease is unclear. Here, we show that intron excision is catalyzed by tetrameric TSEN assembled from inactive heterodimers independently of CLP1. Splice site recognition involves the mature domain and the anticodon-intron base pair of pre-tRNAs. The 2.1-Å resolution X-ray crystal structure of a TSEN15–34 heterodimer and differential scanning fluorimetry analyses show that PCH mutations cause thermal destabilization. While endonuclease activity in recombinant mutant TSEN is unaltered, we observe assembly defects and reduced pre-tRNA cleavage activity resulting in an imbalanced pre-tRNA pool in PCH patient-derived fibroblasts. Our work defines the molecular principles of intron excision in humans and provides evidence that modulation of TSEN stability may contribute to PCH phenotypes.
The HITRAP linear decelerator currently being set up at GSI will provide slow, few keV/u highly charged ions for atomic physics experiments. The expected beam intensity is up to 105 ions per shot. To optimize phase and amplitude of the RF systems intensity, bunch length and kinetic energy of the particles need to be monitored. The bunch length that we need to fit is about 2 ns, which is typically measured by capacitive pickups. However, they do not work for the low beam intensities that we face. We investigated the bunch length with a fast CVD diamond detector working in single particle counting mode. Averaging over 8 shots yields a clear, regular picture of the bunched beam. Energy measurements by capacitive pickups are limited by the presence of intense primary and partially decelerated beam and hence make tuning of the IH-structure impossible. The energy of the decelerated fraction of the beam behind the first deceleration cavity was determined to about 10 % accuracy with a permanent dipole magnet combined with a MCP. Better detector calibration should help reaching the required 1%. Design of the detectors as well as the results of the measurements will be presented.
Introns of human transfer RNA precursors (pre-tRNAs) are excised by the tRNA splicing endonuclease TSEN in complex with the RNA kinase CLP1. Mutations in TSEN/CLP1 occur in patients with pontocerebellar hypoplasia (PCH), however, their role in the disease is unclear. Here, we show that intron excision is catalyzed by tetrameric TSEN assembled from inactive heterodimers independently of CLP1. Splice site recognition involves the mature domain and the anticodon-intron base pair of pre-tRNAs. The 2.1-Å resolution X-ray crystal structure of a TSEN15–34 heterodimer and differential scanning fluorimetry analyses show that PCH mutations cause thermal destabilization. While endonuclease activity in recombinant mutant TSEN is unaltered, we observe assembly defects and reduced pre-tRNA cleavage activity resulting in an imbalanced pre-tRNA pool in PCH patient-derived fibroblasts. Our work defines the molecular principles of intron excision in humans and provides evidence that modulation of TSEN stability may contribute to PCH phenotypes.
The upcoming commissioning of the superconducting (SC) continuous wave Helmholtz linear accelerators first of series cryomodule is going to demand precise alignment of the four internal SC cavities and two SC solenoids. For optimal results, a beam-based alignment method is used to reduce the misalignment of the whole cryomodule, as well as its individual components. A symmetric beam of low transverse emittance is required for this method, which is to be formed by a collimation system. It consists of two separate plates with milled slits, aligned in the horizontal and vertical direction. The collimation system and alignment measurements are proposed, investigated, and realized. The complete setup of this system and its integration into the existing environment at the GSI High Charge State Injector are presented, as well as the results of the recent reference measurements.
Unsere bisherige Kenntnis zur Situation von Crepis praemorsa (Abbiss-Pippau) war ungenügend und wurde im Rahmen eines Kooperationsprojektes mit dem Hessischen Landesamt für Naturschutz, Umwelt und Geologie (HLNUG) erheblich verbessert. Die Untersuchungen zeigen, dass es in Hessen offenbar nur noch acht Vorkommen dieser Art gibt: Drei sehr kleine Reliktpopulationen an der Bergstraße, eine im nordhessischen Bergland und vier in der Rhön, davon zwei sehr kleine. Keine der Populationen kann als groß bezeichnet werden, die Anzahl der Individuen liegt zwischen wenigen Exemplaren bis zum niedrigen dreistelligen Bereich. Lediglich eine Population erscheint aktuell ungefährdet. Fehlende Nutzung oder Pflege und in der Folge Verbrachung und Verbuschung sowie Lichtmangel durch Beschattung sind maßgebliche Gefährdungen. Ohne aktive Hilfsmaßnahmen werden vier dieser acht Populationen in naher Zukunft erlöschen.
In non-hadronic axion models, which have a tree-level axion-electron interaction, the Sun produces a strong axion flux by bremsstrahlung, Compton scattering, and axiorecombination, the "BCA processes." Based on a new calculation of this flux, including for the first time axio-recombination, we derive limits on the axion-electron Yukawa coupling gae and axion-photon interaction strength ga using the CAST phase-I data (vacuum phase). For ma <~ 10 meV/c2 we find ga gae < 8.1 × 10−23 GeV−1 at 95% CL. We stress that a next-generation axion helioscope such as the proposed IAXO could push this sensitivity into a range beyond stellar energy-loss limits and test the hypothesis that white-dwarf cooling is dominated by axion emission.