240 research outputs found
Optical Imaging and Spectroscopic Observation of the Galactic Supernova Remnant G85.9-0.6
Optical CCD imaging with H and [SII] filters and spectroscopic
observations of the galactic supernova remnant G85.9-0.6 have been performed
for the first time. The CCD image data are taken with the 1.5m Russian-Turkish
Telescope (RTT150) at TUBITAK National Observatory (TUG) and spectral data are
taken with the Bok 2.3 m telescope on Kitt Peak, AZ.
The images are taken with narrow-band interference filters H, [SII]
and their continuum. [SII]/H ratio image is performed. The ratio
obtained from [SII]/H is found to be 0.42, indicating that the
remnant interacts with HII regions. G85.9-0.6 shows diffuse-shell morphology.
[SII] average flux ratio is calculated from the
spectra, and the electron density is obtained to be 395 . From
[OIII]/H ratio, shock velocity has been estimated, pre-shock density of
, explosion energy of ergs,
interstellar extinction of , and neutral hydrogen column density
of are reported.Comment: 20 pages, 4 tables, 4 figures. Accepted for publication in
Astrophysics & Space Scienc
Numerical Portrait of a Relativistic BCS Gapped Superfluid
We present results of numerical simulations of the 3+1 dimensional Nambu -
Jona-Lasinio (NJL) model with a non-zero baryon density enforced via the
introduction of a chemical potential mu not equal to 0. The triviality of the
model with a number of dimensions d>=4 is dealt with by fitting low energy
constants, calculated analytically in the large number of colors (Hartree)
limit, to phenomenological values. Non-perturbative measurements of local order
parameters for superfluidity and their related susceptibilities show that, in
contrast to the 2+1 dimensional model, the ground-state at high chemical
potential and low temperature is that of a traditional BCS superfluid. This
conclusion is supported by the direct observation of a gap in the dispersion
relation for 0.5<=(mu a)<=0.85, which at (mu a)=0.8 is found to be roughly 15%
the size of the vacuum fermion mass. We also present results of an initial
investigation of the stability of the BCS phase against thermal fluctuations.
Finally, we discuss the effect of splitting the Fermi surfaces of the pairing
partners by the introduction of a non-zero isospin chemical potential.Comment: 41 pages, 19 figures, uses axodraw.sty, v2: minor typographical
correction
Membrane-Protein Interactions in a Generic Coarse-Grained Model for Lipid Bilayers
We study membrane-protein interactions and membrane-mediated protein-protein
interactions by Monte Carlo simulations of a generic coarse-grained model for
lipid bilayers with cylindrical hydrophobic inclusions. The strength of the
hydrophobic force and the hydrophobic thickness of the proteins are
systematically varied. The results are compared with analytical predictions of
two popular analytical theories: The Landau-de Gennes theory and the elastic
theory. The elastic theory provides an excellent description of the fluctuation
spectra of pure membranes and successfully reproduces the deformation profiles
of membranes around single proteins. However, its prediction for the potential
of mean force between proteins is not compatible with the simulation data for
large distances. The simulations show that the lipid-mediated interactions are
governed by five competing factors: Direct interactions, lipid-induced
depletion interactions, lipid bridging, lipid packing, and a smooth long-range
contribution. The mechanisms leading to "hydrophobic mismatch" interactions are
critically analyzed.Comment: 16 pages, 8 figures, accepted for publication in Biophysical Journa
The tomato receptor CuRe1 senses a cell wall protein to identify Cuscuta as a pathogen
Parasitic plants of the genus Cuscuta penetrate shoots of host plants with haustoria and build a connection to the host vasculature to exhaust water, solutes and carbohydrates. Such infections usually stay unrecognized by the host and lead to harmful host plant damage. Here, we show a molecular mechanism of how plants can sense parasitic Cuscuta. We isolated an 11 kDa protein of the parasite cell wall and identified it as a glycine-rich protein (GRP). This GRP, as well as its minimal peptide epitope Crip21, serve as a pathogen-associated molecular pattern and specifically bind and activate a membrane-bound immune receptor of tomato, the Cuscuta Receptor 1 (CuRe1), leading to defense responses in resistant hosts. These findings provide the initial steps to understand the resistance mechanisms against parasitic plants and further offer great potential for protecting crops by engineering resistance against parasitic plants
Autophosphorylation-based calcium (Ca2+) sensitivity priming and Ca2+/Calmodulin inhibition of Arabidopsis thaliana Ca2+-dependent protein kinase 28 (CPK28)
Plant calcium (Ca2+) dependent protein kinases (CPKs) are composed of a dual specificity (Ser/Thr and Tyr) kinase domain tethered to a Calmodulin-like domain (CLD) via an autoinhibitory junction (J) and represent the primary Ca2+-dependent protein kinase activities in plant systems. While regulation of CPKs by Ca2+ has been extensively studied, the contribution of autophosphorylation in the control of CPK activity is less well understood. Furthermore, whether Calmodulin (CaM) contributes to CPK regulation, as is the case for Ca2+/CaM-dependent protein kinases (CaMKs) outside the plant lineage, remains an open question. We screened a subset of plant CPKs for CaM-binding and found that CPK28 is a high-affinity Ca2+/CaM-binding protein. Using synthetic peptides and native gel electrophoresis, we coarsely mapped the CaM-binding domain to a site within the CPK28 J domain that overlaps with the known site of intramolecular interaction between the J domain and CLD. Peptide kinase activity of fully dephosphorylated CPK28 was Ca2+-responsive and inhibited by Ca2+/CaM. Using in situ autophosphorylated protein, we expand on the known set of CPK28 autophosphorylation sites, and demonstrate that, unexpectedly, autophosphorylated CPK28 had enhanced activity at physiological concentrations of Ca2+ compared to dephosphorylated protein, suggesting that autophosphorylation functions to prime CPK28 for Ca2+-activation. Furthermore, CPK28 autophosphorylation substantially reduced sensitivity of the kinase to Ca2+/CaM inhibition. Overall, our analyses uncover new complexities in the control of CPK28 and provide mechanistic support for Ca2+ signaling specificity through Ca2+ sensor priming
Regulation of steroidogenesis in a primary pigmented nodular adrenocortical disease-associated adenoma leading to virilization and subclinical Cushing's syndrome
Context: Primary pigmented nodular adrenocortical disease (PPNAD) can lead to steroid hormone overproduction. Mutations in the cAMP protein kinase A regulatory subunit type 1A (PRKAR1A) are causative of PPNAD. Steroidogenesis in PPNAD can be modified through a local glucocorticoid feed-forward loop. Objective: Investigation of regulation of steroidogenesis in a case of PPNAD with virilization. Materials and methods : A 33-year-old woman presented with primary infertility due to hyperandrogenism. Elevated levels of testosterone and subclinical ACTH-independent Cushing's syndrome led to the discovery of an adrenal tumor, which was diagnosed as PPNAD. In vivo evaluation of aberrantly expressed hormone receptors showed no steroid response to known stimuli. Genetic analysis revealed a PRKAR1A protein-truncating Q28X mutation. After adrenalectomy, steroid levels normalized. Tumor cells were cultured and steroid
Pathogen effector recognition-dependent association of NRG1 with EDS1 and SAG101 in TNL receptor immunity
Plants utilise intracellular nucleotide-binding, leucine-rich repeat (NLR) immune receptors to detect pathogen effectors and activate local and systemic defence. NRG1 and ADR1 “helper” NLRs (RNLs) cooperate with enhanced disease susceptibility 1 (EDS1), senescence-associated gene 101 (SAG101) and phytoalexin-deficient 4 (PAD4) lipase-like proteins to mediate signalling from TIR domain NLR receptors (TNLs). The mechanism of RNL/EDS1 family protein cooperation is not understood. Here, we present genetic and molecular evidence for exclusive EDS1/SAG101/NRG1 and EDS1/PAD4/ADR1 co-functions in TNL immunity. Using immunoprecipitation and mass spectrometry, we show effector recognition-dependent interaction of NRG1 with EDS1 and SAG101, but not PAD4. An EDS1-SAG101 complex interacts with NRG1, and EDS1-PAD4 with ADR1, in an immune-activated state. NRG1 requires an intact nucleotide-binding P-loop motif, and EDS1 a functional EP domain and its partner SAG101, for induced association and immunity. Thus, two distinct modules (NRG1/EDS1/SAG101 and ADR1/EDS1/PAD4) mediate TNL receptor defence signalling
The urgent need for integrated science to fight COVID-19 pandemic and beyond
The COVID-19 pandemic has become the leading societal concern. The pandemic has shown that the public health
concern is not only a medical problem, but also afects society as a whole; so, it has also become the leading scientifc
concern. We discuss in this treatise the importance of bringing the world’s scientists together to fnd efective solu‑
tions for controlling the pandemic. By applying novel research frameworks, interdisciplinary collaboration promises to
manage the pandemic’s consequences and prevent recurrences of similar pandemics
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Energetic particle influence on the Earth's atmosphere
This manuscript gives an up-to-date and comprehensive overview of the effects of energetic particle precipitation (EPP) onto the whole atmosphere, from the lower thermosphere/mesosphere through the stratosphere and troposphere, to the surface. The paper summarizes the different sources and energies of particles, principally
galactic cosmic rays (GCRs), solar energetic particles (SEPs) and energetic electron precipitation (EEP). All the proposed mechanisms by which EPP can affect the atmosphere
are discussed, including chemical changes in the upper atmosphere and lower thermosphere, chemistry-dynamics feedbacks, the global electric circuit and cloud formation. The role of energetic particles in Earth’s atmosphere is a multi-disciplinary problem that requires expertise from a range of scientific backgrounds. To assist with this synergy, summary tables are provided, which are intended to evaluate the level of current knowledge of the effects of energetic particles on processes in the entire atmosphere
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