1,176 research outputs found
T cell specific adaptor protein (TSAd) promotes interaction of Nck with Lck and SLP-76 in T cells
Background: The Lck and Src binding adaptor protein TSAd (T cell specific adaptor) regulates actin polymerization in T cells and endothelial cells. The molecular details as to how TSAd regulates this process remain to be elucidated. Results: To identify novel interaction partners for TSAd, we used a scoring matrix-assisted ligand algorithm (SMALI), and found that the Src homology 2 (SH2) domain of the actin regulator Non-catalytic region of tyrosine kinase adaptor protein (Nck) potentially binds to TSAd phosphorylated on Tyr280 (pTyr280) and pTyr305. These predictions were confirmed by peptide array analysis, showing direct binding of recombinant Nck SH2 to both pTyr280 and pTyr305 on TSAd. In addition, the SH3 domains of Nck interacted with the proline rich region (PRR) of TSAd. Pull-down and immunoprecipitation experiments further confirmed the Nck-TSAd interactions through Nck SH2 and SH3 domains. In line with this Nck and TSAd co-localized in Jurkat cells as assessed by confocal microscopy and imaging flow cytometry. Co-immunoprecipitation experiments in Jurkat TAg cells lacking TSAd revealed that TSAd promotes interaction of Nck with Lck and SLP-76, but not Vav1. TSAd expressing Jurkat cells contained more polymerized actin, an effect dependent on TSAd exon 7, which includes interactions sites for both Nck and Lck. Conclusions: TSAd binds to and co-localizes with Nck. Expression of TSAd increases both Nck-Lck and Nck-SLP-76 interaction in T cells. Recruitment of Lck and SLP-76 to Nck by TSAd could be one mechanism by which TSAd promotes actin polymerization in activated T cells. © 2015 Hem et al
Semileptonic decays of baryons in a relativistic quark model
We calculate semileptonic decays of light and heavy baryons in a
relativistically covariant constituent quark model. The model is based on the
Bethe-Salpeter-equation in instantaneous approximation. It generates
satisfactory mass spectra for mesons and baryons up to the highest observable
energies. Without introducing additional free parameters we compute on this
basis helicity amplitudes of electronic and muonic semileptonic decays of
baryons. We thus obtain form factor ratios and decay rates in good agreement
with experiment.Comment: 8 pages, 10 figures, 2 tables, typos remove
Dual character of the electronic structure in YBa2Cu4O8: conduction bands of CuO2 planes and CuO chains
We use microprobe Angle-Resolved Photoemission Spectroscopy (muARPES) to
separately investigate the electronic properties of CuO2 planes and CuO chains
in the high temperature superconductor, YBa2Cu4O8. In the CuO2 planes, a two
dimensional (2D) electronic structure with nearly momentum independent bilayer
splitting is observed. The splitting energy is 150 meV at (pi,0), almost 50%
larger than in Bi2Sr2CaCu2O(8+d) and the electron scattering at the Fermi level
in the bonding band is about 1.5 times stronger than in the antibonding band.
The CuO chains have a quasi one dimensional (1D) electronic structure. We
observe two 1D bands separated by ~ 550meV: a conducting band and an insulating
band with an energy gap of ~ 240meV. We find that the conduction electrons are
well confined within the planes and chains with a non-trivial hybridization.Comment: 4 pages, 4 figure
Ocean Dynamics and the Inner Edge of the Habitable Zone for Tidally Locked Terrestrial Planets
Recent studies have shown that ocean dynamics can have a significant warming
effect on the permanent night sides of 1 to 1 tidally locked terrestrial
exoplanets with Earth-like atmospheres and oceans in the middle of the
habitable zone. However, the impact of ocean dynamics on the habitable zone's
boundaries (inner edge and outer edge) is still unknown and represents a major
gap in our understanding of this type of planets. Here we use a coupled
atmosphere-ocean global climate model to show that planetary heat transport
from the day to night side is dominated by the ocean at lower stellar fluxes
and by the atmosphere near the inner edge of the habitable zone. This decrease
in oceanic heat transport (OHT) at high stellar fluxes is mainly due to
weakening of surface wind stress and a decrease in surface shortwave energy
deposition. We further show that ocean dynamics have almost no effect on the
observational thermal phase curves of planets near the inner edge of the
habitable zone. For planets in the habitable zone's middle range, ocean
dynamics moves the hottest spot on the surface eastward from the substellar
point. These results suggest that future studies of the inner edge may devote
computational resources to atmosphere-only processes such as clouds and
radiation. For studies of the middle range and outer edge of the habitable
zone, however, fully coupled ocean-atmosphere modeling will be necessary. Note
that due to computational resource limitations, only one rotation period (60
Earth days) has been systematically examined in this study; future work varying
rotation period as well as other parameters such as atmospheric mass and
composition is required.Comment: 34 pages, 13 figures, and 1 tabl
Electrostatic Interactions of Asymmetrically Charged Membranes
We predict the nature (attractive or repulsive) and range (exponentially
screened or long-range power law) of the electrostatic interactions of
oppositely charged and planar plates as a function of the salt concentration
and surface charge densities (whose absolute magnitudes are not necessarily
equal). An analytical expression for the crossover between attractive and
repulsive pressure is obtained as a function of the salt concentration. This
condition reduces to the high-salt limit of Parsegian and Gingell where the
interaction is exponentially screened and to the zero salt limit of Lau and
Pincus in which the important length scales are the inter-plate separation and
the Gouy-Chapman length. In the regime of low salt and high surface charges we
predict - for any ratio of the charges on the surfaces - that the attractive
pressure is long-ranged as a function of the spacing. The attractive pressure
is related to the decrease in counter-ion concentration as the inter-plate
distance is decreased. Our theory predicts several scaling regimes with
different scaling expressions for the pressure as function of salinity and
surface charge densities. The pressure predictions can be related to surface
force experiments of oppositely charged surfaces that are prepared by coating
one of the mica surfaces with an oppositely charged polyelectrolyte
SPH modelling of turbulent open channel flow over and within natural gravel beds with rough interfacial boundaries
Smoothed Particle Hydrodynamics (SPH) is brought to a level that can be applied to simulate turbulent open channel flows over and within natural porous gravel beds. For this, improvements have been made with regards to i) turbulence modelling, ii) open boundaries (inflow and outflow), and iii) treatment of the rough interface boundary between the porous bed and the overlying free-flow. Flow through the porous bed is simulated macroscopically, and the coefficients of the drag closure model are carefully determined at different layers of the flow; the effect of turbulence is taken into account using a three-layer mixing-length model; and a porous inflow boundary at the inlet as well as an imaginary pressure wall at the outlet are introduced to obtain the required steady and uniform flow conditions. The developed model is then used to simulate eight test cases with two bed conditions, each with four flow conditions. Through the velocity analysis, a nearly S-shaped distribution is observed within the roughness layer for the present test cases. The comparison of the results of the velocity and shear stress with a set of experimental data reveals that the SPH model with the present drag and turbulence closure models as well as the proposed inflow/outflow boundary techniques is capable of simulating complex turbulent channel flows over highly sheared natural porous beds
Visual outcome following phacoemulsification in English Cocker Spaniels with suspected progressive retinal atrophy: A retrospective multicenter study of 54 cases (2002-2017)
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