808 research outputs found
Structural and mutational analysis of the ribosome-arresting human XBP1u
XBP1u, a central component of the unfolded protein response (UPR), is a mammalian protein containing a functionally critical translational arrest peptide (AP). Here, we present a 3 angstrom cryo-EM structure of the stalled human XBP1u AP. It forms a unique turn in the ribosomal exit tunnel proximal to the peptidyl transferase center where it causes a subtle distortion, thereby explaining the temporary translational arrest induced by XBP1u. During ribosomal pausing the hydrophobic region 2 (HR2) of XBP1u is recognized by SRP, but fails to efficiently gate the Sec61 translocon. An exhaustive mutagenesis scan of the XBP1u AP revealed that only 8 out of 20 mutagenized positions are optimal;in the remaining 12 positions, we identify 55 different mutations increase the level of translational arrest. Thus, the wildtype XBP1u AP induces only an intermediate level of translational arrest, allowing efficient targeting by SRP without activating the Sec61 channel
Environmental Sustainability Post-COVID-19: Scrutinizing Popular Hypotheses from a Social Science Perspective
There is an increasingly vocal debate on potential long-term changes in environmental sustainability spurred by the global COVID-19 pandemic. This article scrutinizes the social science basis of selected popular hypotheses regarding the nexus between the COVID-19 pandemic and the societal transitions towards environmental sustainability. It presents results that were derived through an interdisciplinary dialogue among social scientists. First, it is confirmed that the COVID-19 crisis has likely created a potential window of opportunity for societal change. Yet, to ensure that societal change is enduring and actually supporting the transition towards environmental sustainability, a clear and well-targeted political framework guiding private investments and behavior is required. Second, it is emphasized that there are important structural differences between the COVID-19 crisis and environmental crises, like time scales. Consequently, many strategies used to address the COVID-19 crisis are hardly suitable for long-term transitions towards environmental sustainability. Third, it is argued that transitions towards environmental sustainability—building both on reducing environmental degradation and building socio-techno-ecological resilience—may create co-benefits in terms of preventing and coping with potential future pandemics. However, research still needs to explore how big these synergies are (and whether trade-offs are also possible), and what type of governance framework they require to materialize
Narrado por un mito: Felix Krull, de Thomas Mann
This article proposes an approach to the novel Bekenntnisse des Hochstaplers Felix Krull by Thomas Mann from the point of view of the imaginal psychology of James Hillman. From this perspective the novel seems to illustrate the most innovative thesis of that psychology, which is especially relevant for having been written prior to the formulation of Hillman’s theories. The unplanned correspondence between both ways of thinking furnishes a valuable argument that supports the new conception of human psyche introduced by Carl Gustav Jung and developed in this way by James Hillman.El presente artículo propone una lectura de la novela de Thomas Mann desde la óptica de la psicología imaginal de James Hillman. En esta perspectiva la novela parece ofrecer una ilustración de las tesis más innovadoras de dicha psicología, lo que resulta especialmente relevante por haber sido escrita con antelación a la formulación de las teorías del pensador estadounidense. La impremeditada correspondencia entre ambos pensamientos suministra un argumento digno de tenerse en cuenta a favor de la innovadora concepción de la psique humana inaugurada por Carl Gustav Jung y desarrollada en esta línea por James Hillman
Radiofrequency multipole traps: Tools for spectroscopy and dynamics of cold molecular ions
Multipole radiofrequency ion traps are a highly versatile tool to study
molecular ions and their interactions in a well-controllable environment. In
particular the cryogenic 22-pole ion trap configuration is used to study
ion-molecule reactions and complex molecular spectroscopy at temperatures
between few Kelvin and room temperatures. This article presents a tutorial on
radiofrequency ion trapping in multipole electrode configurations. Stable
trapping conditions and buffer gas cooling, as well as important heating
mechanisms, are discussed. In addition, selected experimental studies on cation
and anion-molecule reactions and on spectroscopy of trapped ions are reviewed.
Starting from these studies an outlook on the future of multipole ion trap
research is given
A process-based model of conifer forest structure and function with special emphasis on leaf lifespan
We describe the University of Sheffield Conifer Model (USCM), a process-based approach for simulating conifer forest carbon, nitrogen, and water fluxes by up-scaling widely applicable relationships between leaf lifespan and function. The USCM is designed to predict and analyze the biogeochemistry and biophysics of conifer forests that dominated the ice-free high-latitude regions under the high pCO2 “greenhouse” world 290–50 Myr ago. It will be of use in future research investigating controls on the contrasting distribution of ancient evergreen and deciduous forests between hemispheres, and their differential feedbacks on polar climate through the exchange of energy and materials with the atmosphere. Emphasis is placed on leaf lifespan because this trait can be determined from the anatomical characteristics of fossil conifer woods and influences a range of ecosystem processes. Extensive testing of simulated net primary production and partitioning, leaf area index, evapotranspiration, nitrogen uptake, and land surface energy partitioning showed close agreement with observations from sites across a wide climatic gradient. This indicates the generic utility of our model, and adequate representation of the key processes involved in forest function using only information on leaf lifespan, climate, and soils
Conformational control of integrin subtype selectivity in isoDGR peptide motifs: A biological switch
Thumbnail image of graphical abstract
The rearrangement of asparagine to isoaspartate (isoD) is responsible for the deactivation of many functional proteins. However, the isoDGR motif, which is optimally presented as a conformationally controlled cyclic pentapeptide, binds selectively to a5ß1 integrin (see the docking model) with an affinity comparable to that of the peptidic antitumor agent CilengitidePeer ReviewedPostprint (published version
Observation of two new baryon resonances
Two structures are observed close to the kinematic threshold in the mass spectrum in a sample of proton-proton collision data, corresponding
to an integrated luminosity of 3.0 fb recorded by the LHCb experiment.
In the quark model, two baryonic resonances with quark content are
expected in this mass region: the spin-parity and
states, denoted and .
Interpreting the structures as these resonances, we measure the mass
differences and the width of the heavier state to be
MeV,
MeV,
MeV, where the first and second
uncertainties are statistical and systematic, respectively. The width of the
lighter state is consistent with zero, and we place an upper limit of
MeV at 95% confidence level. Relative
production rates of these states are also reported.Comment: 17 pages, 2 figure
Measurement of the mass and lifetime of the baryon
A proton-proton collision data sample, corresponding to an integrated
luminosity of 3 fb collected by LHCb at and 8 TeV, is used
to reconstruct , decays. Using the , decay mode for calibration, the lifetime ratio and absolute
lifetime of the baryon are measured to be \begin{align*}
\frac{\tau_{\Omega_b^-}}{\tau_{\Xi_b^-}} &= 1.11\pm0.16\pm0.03, \\
\tau_{\Omega_b^-} &= 1.78\pm0.26\pm0.05\pm0.06~{\rm ps}, \end{align*} where the
uncertainties are statistical, systematic and from the calibration mode (for
only). A measurement is also made of the mass difference,
, and the corresponding mass, which
yields \begin{align*} m_{\Omega_b^-}-m_{\Xi_b^-} &= 247.4\pm3.2\pm0.5~{\rm
MeV}/c^2, \\ m_{\Omega_b^-} &= 6045.1\pm3.2\pm 0.5\pm0.6~{\rm MeV}/c^2.
\end{align*} These results are consistent with previous measurements.Comment: 11 pages, 5 figures, All figures and tables, along with any
supplementary material and additional information, are available at
https://lhcbproject.web.cern.ch/lhcbproject/Publications/LHCbProjectPublic/LHCb-PAPER-2016-008.htm
Study of and decays and determination of the CKM angle
We report a study of the suppressed and favored
decays, where the neutral meson is detected
through its decays to the and CP-even and
final states. The measurement is carried out using a proton-proton
collision data sample collected by the LHCb experiment, corresponding to an
integrated luminosity of 3.0~fb. We observe the first significant
signals in the CP-even final states of the meson for both the suppressed
and favored modes, as well as
in the doubly Cabibbo-suppressed final state of the decay. Evidence for the ADS suppressed decay , with , is also presented. From the observed
yields in the , and their
charge conjugate decay modes, we measure the value of the weak phase to be
. This is one of the most precise
single-measurement determinations of to date.Comment: 22 pages, 9 figures; All figures and tables, along with any
supplementary material and additional information, are available at
https://lhcbproject.web.cern.ch/lhcbproject/Publications/LHCbProjectPublic/LHCb-PAPER-2015-020.htm
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