University of Fribourg

About: University of Fribourg is a education organization based out in Fribourg, Freiburg, Switzerland. It is known for research contribution in the topics: Population & Context (language use). The organization has 6040 authors who have published 14975 publications receiving 542500 citations. The organization is also known as: UNIFR & Universität Freiburg.

Mutation of the Circadian Clock Gene Per2 Alters Vascular Endothelial Function

Abstract: Background—The circadian clock regulates biological processes including cardiovascular function and metabolism. In the present study, we investigated the role of the circadian clock gene Period2 (Per2) in endothelial function in a mouse model. Methods and Results—Compared with the wild-type littermates, mice with Per2 mutation exhibited impaired endotheliumdependent relaxations to acetylcholine in aortic rings suspended in organ chambers. During transition from the inactive to active phase, this response was further increased in the wild-type mice but further decreased in the Per2 mutants. The endothelial dysfunction in the Per2 mutants was also observed with ionomycin, which was improved by the cyclooxygenase inhibitor indomethacin. No changes in the expression of endothelial acetylcholine-M3 receptor or endothelial nitric oxide synthase protein but increased cyclooxygenase-1 (not cyclooxygenase-2) protein levels were observed in the aortas of the Per2 mutants. Compared with Per2 mutants, a greater endothelium-dependent relaxation to ATP was observed in the wild-type mice, which was reduced by indomethacin. In quiescent aortic rings, ATP caused greater endothelium-dependent contractions in the Per2 mutants than in the wild-type mice, contractions that were abolished by indomethacin. The endothelial dysfunction in the Per2 mutant mice is not associated with hypertension or dyslipidemia. Conclusions—Mutation in the Per2 gene in mice is associated with aortic endothelial dysfunction involving decreased production of NO and vasodilatory prostaglandin(s) and increased release of cyclooxygenase-1–derived vasoconstrictor(s). The results suggest an important role of the Per2 gene in maintenance of normal cardiovascular functions. (Circulation. 2007;115:2188-2195.)

New Zealand English: Its Origins and Evolution

Abstract: 1. Introduction 2. Overview and background 3. The historical background 4. Previous attempts to explain the origins of New Zealand English 5. Methodology 6. The variables of early New Zealand English 7. The origins of New Zealand English: reflections from the ONZE data 8. Implications for language change Appendices.

Measurement of the inelastic proton-proton cross section at √s=13 TeV with the ATLAS detector at the LHC

Abstract: This Letter presents a measurement of the inelastic proton-proton cross section using 60 μb^{-1} of pp collisions at a center-of-mass energy sqrt[s] of 13 TeV with the ATLAS detector at the LHC. Inelastic interactions are selected using rings of plastic scintillators in the forward region (2.07 10^{-6}, where M_{X} is the larger invariant mass of the two hadronic systems separated by the largest rapidity gap in the event. In this ξ range the scintillators are highly efficient. For diffractive events this corresponds to cases where at least one proton dissociates to a system with M_{X}>13 GeV. The measured cross section is compared with a range of theoretical predictions. When extrapolated to the full phase space, a cross section of 78.1±2.9 mb is measured, consistent with the inelastic cross section increasing with center-of-mass energy.

The glutathione-deficient mutant pad2-1 accumulates lower amounts of glucosinolates and is more susceptible to the insect herbivore Spodoptera littoralis.

Abstract: Summary Plants often respond to pathogen or insect attack by inducing the synthesis of toxic compounds such as phytoalexins and glucosinolates (GS). The Arabidopsis mutant pad2-1 has reduced levels of the phytoalexin camalexin and is known for its increased susceptibility to fungal and bacterial pathogens. We found that pad2-1 is also more susceptible to the generalist insect Spodoptera littoralis but not to the specialist Pieris brassicae. The PAD2 gene encodes a gamma-glutamylcysteine synthetase that is involved in glutathione (GSH) synthesis, and consequently the pad2-1 mutant contains about 20% of the GSH found in wild-type plants. Lower GSH levels of pad2-1 were correlated with reduced accumulation of the two major indole and aliphatic GSs of Arabidopsis, indolyl-3-methyl-GS and 4-methylsulfinylbutyl-GS, in response to insect feeding. This effect was specific to GSH, was not complemented by treatment of pad2-1 with the strong reducing agent dithiothreitol, and was not observed with the ascorbate-deficient mutant vtc1-1. In contrast to the jasmonate-insensitive mutant coi1-1, expression of insect-regulated and GS biosynthesis genes was not affected in pad2-1. Our data suggest a crucial role for GSH in GS biosynthesis and insect resistance.

Calibration uncertainty in molecular dating analyses: there is no substitute for the prior evaluation of time priors

Abstract: Calibration is the rate-determining step in every molecular clock analysis and, hence, considerable effort has been expended in the development of approaches to distinguish good from bad calibrations. These can be categorized into a priori evaluation of the intrinsic fossil evidence, and a posteriori evaluation of congruence through cross-validation. We contrasted these competing approaches and explored the impact of different interpretations of the fossil evidence upon Bayesian divergence time estimation. The results demonstrate that a posteriori approaches can lead to the selection of erroneous calibrations. Bayesian posterior estimates are also shown to be extremely sensitive to the probabilistic interpretation of temporal constraints. Furthermore, the effective time priors implemented within an analysis differ for individual calibrations when employed alone and in differing combination with others. This compromises the implicit assumption of all calibration consistency methods, that the impact of an individual calibration is the same when used alone or in unison with others. Thus, the most effective means of establishing the quality of fossil-based calibrations is through a priori evaluation of the intrinsic palaeontological, stratigraphic, geochronological and phylogenetic data. However, effort expended in establishing calibrations will not be rewarded unless they are implemented faithfully in divergence time analyses.