Plant cells sheath themselves in a complex lattice of polysaccharides, proteins and enzymes forming an integral matrix known as the cell wall. Cellulose microfibrils, the primary component of cell ...walls, are synthesized at the plasma membrane by CELLULOSE SYNTHASE A (CESA) proteins throughout cellular growth and are responsible for turgor-driven anisotropic expansion. Associations between hormone signaling and cell wall biosynthesis have long been suggested, but recently direct links have been found revealing hormones play key regulatory roles in cellulose biosynthesis. The radially swollen 1 (rsw1) allele of Arabidopsis thaliana CESA1 harbors a single amino acid change that renders the protein unstable at high temperatures. We used the conditional nature of rsw1 to investigate how auxin contributes to isotropic growth. We found that exogenous auxin treatment reduces isotropic swelling in rsw1 roots at the restrictive temperature of 30�C. We also discovered decreases in auxin influx between rsw1 and wild-type roots via confocal imaging of AUX1-YFP, even at the permissive temperature of 19�C. Moreover, rsw1 displayed mis-expression of auxin-responsive and CESA genes. Additionally, we found altered auxin maxima in rsw1 mutant roots at the onset of swelling using DII-VENUS and DR5:vYFP auxin reporters. Overall, we conclude disrupted cell wall biosynthesis perturbs auxin transport leading to altered auxin homeostasis impacting both anisotropic and isotropic growth that affects overall root morphology.
Homoepitaxy provides an ideal testing ground for fundamental concepts in film growth. The rich variety of complex far-from-equilibrium morphologies which can form during deposition contrasts with the ...simple equilibrium structure of homoepitaxial films. These complex morphologies result from the inhibition on the time-scale of deposition of various equilibrating surface diffusion processes. A sophisticated framework for analysis of such phenomena derives from the concepts and methodology of Statistical Physics. Kinetic Monte Carlo (KMC) simulation of suitable atomistic lattice–gas models has elucidated the growth behavior of numerous specific systems. In this review, we describe in detail
submonolayer nucleation and growth of two-dimensional islands during deposition. The traditional mean-field treatment is quite successful in capturing the behavior of mean island densities, but it fails to predict island size distributions. The latter are provided by simulation of appropriate atomistic models, as well as by suitable hybrid models. Recent developments towards providing reliable analytic beyond-mean-field theories are also discussed.
Kinetic roughening of multilayer films during deposition is also described with particular emphasis on the formation of mounds (multilayer stacks of 2D islands) induced by step-edge barriers to downward transport. We describe results for mound evolution from realistic atomistic simulations, predictions of phenomenological continuum theories, and efforts to derive more reliable coarse-grained formulations. For both regimes, we demonstrate how atomistic modeling can be used extract key activation barriers by comparison with experimental data from scanning tunneling microscopy and surface sensitive diffraction. Significantly, suitable tailored atomistic models are often shown to have predictive capability for growth over a broad range of temperatures. Finally, we comment briefly on other deposition processes such as heteroepitaxial growth and chemisorption.
BRAF V600E is the most common mutation in conventional ameloblastoma (AM) of the mandible. In contrast, maxillary AMs appear to harbor more frequently RAS, FGFR2, or SMO mutations. Unicystic ...ameloblastoma (UAM) is considered a less aggressive variant of ameloblastoma, amenable to more conservative treatment, and classified as a distinct entity. The aim of this study was to characterize the mutation profile of UAM (n = 39) and to compare it to conventional AM (n = 39). The associations between mutation status and recurrence probability were also analyzed. In the mandible, 94% of UAMs (29/31, including 8/8 luminal, 6/8 intraluminal, and 15/15 mural subtypes) and 74% of AMs (28/38) revealed BRAF V600E mutations. Among the BRAF wild-type cases, 1 UAM showed a missense SMO mutation (p.L412F), whereas 2 NRAS (p.Q61R), 2 HRAS (p.Q61R), and 2 FGFR2 (p.C383R) activating mutations were identified in AM. Of the 3 maxillary UAMs, only 1 revealed a BRAF V600E mutation. Taken together, our findings demonstrate high frequency of activating BRAF V600E mutations in both UAM and AM of the mandible. In maxillary UAMs, the BRAF V600E mutation prevalence appears to be lower as was shown for AM previously. It could therefore be argued that UAM and AM are part of the spectrum of the same disease. AMs without BRAF V600E mutations were associated with an increased rate of local recurrence (P = 0.0003), which might indicate that routine mutation testing also has an impact on prognosis.
We report on the measurement of the γp→J/ψp cross section from E_{γ}=11.8 GeV down to the threshold at 8.2 GeV using a tagged photon beam with the GlueX experiment. We find that the total cross ...section falls toward the threshold less steeply than expected from two-gluon exchange models. The differential cross section dσ/dt has an exponential slope of 1.67±0.39 GeV^{-2} at 10.7 GeV average energy. The LHCb pentaquark candidates P_{c}^{+} can be produced in the s channel of this reaction. We see no evidence for them and set model-dependent upper limits on their branching fractions B(P_{c}^{+}→J/ψp) and cross sections σ(γp→P_{c}^{+})×B(P_{c}^{+}→J/ψp).
Leishmaniasis is increasingly reported among travellers. Leishmania species vary in sensitivity to available therapies. Fast and reliable molecular techniques have made species-directed treatment ...feasible. Many treatment trials have been designed poorly, thus developing evidence-based guidelines for species-directed treatment is difficult. Published guidelines on leishmaniasis in travellers do not aim to be comprehensive or do not quantify overall treatment success for available therapies. We aimed at providing comprehensive species-directed treatment guidelines.
English literature was searched using PubMed. Trials and observational studies were included if all cases were parasitologically confirmed, the Leishmania species was known, clear clinical end-points and time points for evaluation of treatment success were defined, duration of follow-up was adequate and loss to follow-up was acceptable. The proportion of successful treatment responses was pooled using mixed effects methods to estimate the efficacy of specific therapies. Final ranking of treatment options was done by an expert panel based on pooled efficacy estimates and practical considerations. 168 studies were included, with 287 treatment arms. Based on Leishmania species, symptoms and geography, 25 clinical categories were defined and therapy options ranked. In 12/25 categories, proposed treatment agreed with highest efficacy data from literature. For 5/25 categories no literature was found, and in 8/25 categories treatment advise differed from literature evidence. For uncomplicated cutaneous leishmaniasis, combination of intralesional antimony with cryotherapy is advised, except for L. guyanensis and L. braziliensis infections, for which systemic treatment is preferred. Treatment of complicated (muco)cutaneous leishmaniasis differs per species. For visceral leishmaniasis, liposomal amphotericin B is treatment of choice.
Our study highlights current knowledge about species-directed therapy of leishmaniasis in returning travellers and also demonstrates lack of evidence for treatment of several clinical categories. New data can easily be incorporated in the presented overview. Updates will be of use for clinical decision making and for defining further research.
Celotno besedilo
Dostopno za:
DOBA, IZUM, KILJ, NUK, PILJ, PNG, SAZU, SIK, UILJ, UKNU, UL, UM, UPUK
Auxin, microtubules, and vesicle trafficking Lehman, Thiel A.; Smertenko, Andrei; Sanguinet, Karen A.
Journal of experimental botany,
06/2017, Letnik:
68, Številka:
13
Journal Article
Recenzirano
Odprti dostop
Plant morphogenesis depends on the synchronized anisotropic expansion of individual cells in response to developmental and environmental cues. The magnitude of cell expansion depends on the ...biomechanical properties of the cell wall, which in turn depends on both its biosynthesis and extensibility. Although the control of cell expansion by the phytohormone auxin is well established, its regulation of cell wall composition, trafficking of H⁺-ATPases, and K⁺ influx that drives growth is still being elucidated. Furthermore, the maintenance of auxin fluxes via the interaction between the cytoskeleton and PIN protein recycling on the plasma membrane remains under investigation. This review proposes a model that describes how the cell wall, auxin, microtubule binding-protein CLASP and Kin7/separase complexes, and vesicle trafficking are co-ordinated on a cellular level to mediate cell wall loosening during cell expansion.
Abstract
With the increasing pressure to decarbonize our society, green hydrogen has been identified as a key element in a future fossil fuel-free energy infrastructure. Solar water splitting through ...photoelectrochemical approaches is an elegant way to produce green hydrogen, but for low-value products like hydrogen, photoelectrochemical production pathways are difficult to be made economically competitive. A possible solution is to co-produce value-added chemicals. Here, we propose and demonstrate the in situ use of (photo)electrochemically generated H
2
for the homogeneous hydrogenation of itaconic acid—a biomass-derived feedstock—to methyl succinic acid. Coupling these two processes offers major advantages in terms of stability and reaction flexibility compared to direct electrochemical hydrogenation, while minimizing the overpotential. An overall conversion of up to ~60% of the produced hydrogen is demonstrated for our coupled process, and a techno-economic assessment of our proposed device further reveals the benefit of coupling solar hydrogen production to a chemical transformation.
Electronic Control of Friction in Silicon pn Junctions Park, Jeong Young; Ogletree, D. F.; Thiel, P. A. ...
Science (American Association for the Advancement of Science),
07/2006, Letnik:
313, Številka:
5784
Journal Article
Recenzirano
Odprti dostop
A remarkable dependence of the friction force on carrier concentration was found on doped silicon substrates. The sample was a nearly intrinsic n-type Si(100) wafer patterned with 2-micrometer-wide ...stripes of highly B-doped p-type material. The counter surface was the tip of an atomic force microscope coated with conductive titanium nitride. The local carrier concentration was controlled through application of forward or reverse bias voltages between the tip and the sample in the p and the n regions. Charge depletion or accumulation resulted in substantial differences in friction force. The results demonstrate the capability to electronically control friction in semiconductor devices, with potential applications in nanoscale machines containing moving parts.
Summary
Here, we discover a player in root development. Recovered from a forward‐genetic screen in Brachypodium distachyon, the buzz mutant initiates root hairs but they fail to elongate. In ...addition, buzz roots grow twice as fast as wild‐type roots. Also, lateral roots show increased sensitivity to nitrate, whereas primary roots are less sensitive to nitrate.
Using whole‐genome resequencing, we identified the causal single nucleotide polymorphism as occurring in a conserved but previously uncharacterized cyclin‐dependent kinase (CDK)‐like gene. The buzz mutant phenotypes are rescued by the wild‐type B. distachyon BUZZ coding sequence and by an apparent homolog in Arabidopsis thaliana. Moreover, T‐DNA mutants in A. thaliana BUZZ have shorter root hairs.
BUZZ mRNA localizes to epidermal cells and develops root hairs and, in the latter, partially colocalizes with the NRT1.1A nitrate transporter. Based on qPCR and RNA‐Seq, buzz overexpresses ROOT HAIRLESS LIKE SIX‐1 and ‐2 and misregulates genes related to hormone signaling, RNA processing, cytoskeletal, and cell wall organization, and to the assimilation of nitrate.
Overall, these data demonstrate that BUZZ is required for tip growth after root hair initiation and root architectural responses to nitrate.
The first measurement of transverse-spin-dependent azimuthal asymmetries in the pion-induced Drell-Yan (DY) process is reported. We use the CERN SPS 190 GeV/c π^{-} beam and a transversely polarized ...ammonia target. Three azimuthal asymmetries giving access to different transverse-momentum-dependent (TMD) parton distribution functions (PDFs) are extracted using dimuon events with invariant mass between 4.3 GeV/c^{2} and 8.5 GeV/c^{2}. Within the experimental uncertainties, the observed sign of the Sivers asymmetry is found to be consistent with the fundamental prediction of quantum chromodynamics (QCD) that the Sivers TMD PDFs extracted from DY have a sign opposite to the one extracted from semi-inclusive deep-inelastic scattering (SIDIS) data. We present two other asymmetries originating from the pion Boer-Mulders TMD PDFs convoluted with either the nucleon transversity or pretzelosity TMD PDFs. A recent COMPASS SIDIS measurement was obtained at a hard scale comparable to that of these DY results. This opens the way for possible tests of fundamental QCD universality predictions.
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