Your browser doesn't support javascript.
loading
Mostrar: 20 | 50 | 100
Resultados 1 - 20 de 1.443
Filtrar
Más filtros

Banco de datos
Tipo del documento
Intervalo de año de publicación
1.
Proc Natl Acad Sci U S A ; 120(1): e2212987120, 2023 01 03.
Artículo en Inglés | MEDLINE | ID: mdl-36574700

RESUMEN

Many receptors signal upon phosphorylation of tyrosine-based motifs in their cytosolic tail, with intrinsic disorder as a common feature. Studies on CD3ζ and CD3ε tails, which are disordered and polybasic, suggested regulation of phosphorylation through accessibility of tyrosines, governed by electrostatic interactions with membrane anionic lipids. We noticed characteristics of intrinsic disorder and previously unappreciated features in tyrosine-based motif-bearing cytosolic tails of many, especially, inhibitory receptors. They are neutral or acidic polyampholytes, with acidic and basic residues linearly segregated. To explore roles of these electrostatic features, we studied inhibitory killer-cell immunoglobulin-like receptor (KIR). Its cytosolic tail is a disordered neutrally charged polyampholyte, wherein juxtamembrane and membrane distal stretches are basic, and the intervening stretch is acidic. Despite lacking net charge, it interacted electrostatically with the plasma membrane. The juxtamembrane stretch was crucial for overall binding, which sequestered tyrosines in the lipid bilayer and restrained their constitutive phosphorylation. Human leukocyte antigen-C ligand binding to KIR released its tail from the plasma membrane to initiate signaling. Tail release occurred independently of KIR polymerization, clustering, or tyrosine phosphorylation, but required acidic residues of the acidic stretch. Tail interaction with the plasma membrane dictated signaling strength of KIR. These results revealed an electrostatic protein-lipid interaction that is unusual in being governed by segregated clusters of acidic and basic residues in polyampholytic disordered region of protein. In contrast to previously known, segregated distribution of oppositely charged residues made both binding and unbinding modules inherent to receptor tail, which could make the interaction an independent signaling switch.


Asunto(s)
Receptores KIR , Transducción de Señal , Humanos , Electricidad Estática , Membrana Celular , Fosforilación , Lípidos de la Membrana , Tirosina/química
2.
PLoS Genet ; 19(1): e1010601, 2023 01.
Artículo en Inglés | MEDLINE | ID: mdl-36706155

RESUMEN

Timely detection and repair of envelope damage are paramount for bacterial survival. The Regulator of Capsule Synthesis (Rcs) stress response can transduce the stress signals across the multilayered gram-negative cell envelope to regulate gene expression in the cytoplasm. Previous studies defined the overall pathway, which begins with the sensory lipoprotein RcsF interacting with several outer membrane proteins (OMPs). RcsF can also interact with the periplasmic domain of the negative regulator IgaA, derepressing the downstream RcsCDB phosphorelay. However, how the RcsF/IgaA interaction is regulated at the molecular level to activate the signaling in response to stress remains poorly understood. In this study, we used a site-saturated mutant library of rcsF to carry out several independent genetic screens to interrogate the mechanism of signal transduction from RcsF to IgaA. We analyzed several distinct classes of rcsF signaling mutants, and determined the region of RcsF that is critically important for signal transduction. This region is bifunctional as it is important for RcsF interaction with both IgaA and OMPs. The mutant analysis provides strong evidence for conformational changes in the RcsF/OMP complex mediating signal transduction to IgaA, and the first direct evidence that OMPs play an important regulatory role in Rcs signaling.


Asunto(s)
Proteínas de la Membrana Bacteriana Externa , Proteínas de Escherichia coli , Escherichia coli , Proteínas de la Membrana Bacteriana Externa/genética , Proteínas de la Membrana Bacteriana Externa/metabolismo , Membrana Celular/genética , Membrana Celular/metabolismo , Escherichia coli/genética , Escherichia coli/metabolismo , Proteínas de Escherichia coli/genética , Proteínas de Escherichia coli/metabolismo , Transducción de Señal/genética
3.
Plant J ; 2024 Jul 11.
Artículo en Inglés | MEDLINE | ID: mdl-38990624

RESUMEN

Enhancing maize kernel oil is vital for improving the bioavailability of fat-soluble vitamins. Here, we combined favourable alleles of dgat1-2 and fatb into parental lines of four multi-nutrient-rich maize hybrids (APTQH1, APTQH4, APTQH5 and APTQH7) using marker-assisted selection (MAS). Parental lines possessed favourable alleles of crtRB1, lcyE, vte4 and opaque2 genes. Gene-specific markers enabled successful foreground selection in BC1F1, BC2F1 and BC2F2, while background selection using genome-wide microsatellite markers (127-132) achieved 93% recurrent parent genome recovery. Resulting inbreds exhibited significantly higher oil (6.93%) and oleic acid (OA, 40.49%) and lower palmitic acid (PA, 14.23%) compared to original inbreds with elevated provitamin A (11.77 ppm), vitamin E (16.01 ppm), lysine (0.331%) and tryptophan (0.085%). Oil content significantly increased from 4.80% in original hybrids to 6.73% in reconstituted hybrids, making them high-oil maize hybrids. These hybrids displayed 35.70% increment in oil content and 51.56% increase in OA with 36.32% reduction in PA compared to original hybrids, while maintaining higher provitamin A (two-fold), vitamin E (nine-fold), lysine (two-fold) and tryptophan (two-fold) compared to normal hybrids. Lipid health indices showed improved atherogenicity, thrombogenicity, cholesterolaemic, oxidability, peroxidizability and nutritive values in MAS-derived genotypes over original versions. Besides, the MAS-derived inbreds and hybrids exhibited comparable grain yield and phenotypic characteristics to the original versions. The maize hybrids developed in the study possessed high-yielding ability with high kernel oil and OA, low PA, better fatty acid health and nutritional properties, higher multi-vitamins and balanced amino acids, which hold immense significance to address malnutrition and rising demand for oil sustainably in a fast-track manner.

4.
Mol Microbiol ; 120(3): 397-407, 2023 09.
Artículo en Inglés | MEDLINE | ID: mdl-37455652

RESUMEN

The ß-barrel assembly machinery (Bam) complex facilitates the assembly of outer membrane proteins (OMPs) in gram-negative bacteria. The Bam complex is conserved and essential for bacterial viability and consists of five subunits, BamA-E. BamA is the transmembrane component, and its ß-barrel domain opens laterally to allow folding and insertion of incoming OMPs. The remaining components are regulatory, among which only BamD is essential. Previous studies suggested that BamB regulates BamA directly, while BamE and BamC serve as BamD regulators. However, specific molecular details of their functions remain unknown. Our previous research demonstrated that BamE plays a specialized role in assembling the complex between the lipoprotein RcsF and its OMP partners, required for the Regulator of Capsule Synthesis (Rcs) stress response. Here, we used RcsF/OmpA as a model substrate to investigate BamE function. Our results challenge the current view that BamE only serves as a BamD regulator. We show that BamE also directly interacts with BamA. BamE interaction with both BamA and BamD is important for function. Our genetic and biochemical analysis shows that BamE stabilizes the Bam complex and promotes bidirectional signaling interaction between BamA and BamD. This BamE function becomes essential when direct BamA/BamD communication is impeded.


Asunto(s)
Proteínas de Escherichia coli , Proteínas de Escherichia coli/metabolismo , Escherichia coli/metabolismo , Proteínas de la Membrana Bacteriana Externa/metabolismo , Lipoproteínas/genética , Lipoproteínas/metabolismo
5.
J Synchrotron Radiat ; 31(Pt 3): 578-589, 2024 May 01.
Artículo en Inglés | MEDLINE | ID: mdl-38530831

RESUMEN

The beamline optics and endstations at branch B of the Versatile Soft X-ray (VerSoX) beamline B07 at Diamond Light Source are described. B07-B provides medium-flux X-rays in the range 45-2200 eV from a bending magnet source, giving access to local electronic structure for atoms of all elements from Li to Y. It has an endstation for high-throughput X-ray photoelectron spectroscopy (XPS) and near-edge X-ray absorption fine-structure (NEXAFS) measurements under ultrahigh-vacuum (UHV) conditions. B07-B has a second endstation dedicated to NEXAFS at pressures from UHV to ambient pressure (1 atm). The combination of these endstations permits studies of a wide range of interfaces and materials. The beamline and endstation designs are discussed in detail, as well as their performance and the commissioning process.

6.
Planta ; 259(6): 144, 2024 May 06.
Artículo en Inglés | MEDLINE | ID: mdl-38709333

RESUMEN

MAIN CONCLUSION: Silicon application mitigates phosphate deficiency in barley through an interplay with auxin and nitric oxide, enhancing growth, photosynthesis, and redox balance, highlighting the potential of silicon as a fertilizer for overcoming nutritional stresses. Silicon (Si) is reported to attenuate nutritional stresses in plants, but studies on the effect of Si application to plants grown under phosphate (Pi) deficiency are still very scarce, especially in barley. Therefore, the present work was undertaken to investigate the potential role of Si in mitigating the adverse impacts of Pi deficiency in barley Hordeum vulgare L. (var. BH902). Further, the involvement of two key regulatory signaling molecules--auxin and nitric oxide (NO)--in Si-induced tolerance against Pi deficiency in barley was tested. Morphological attributes, photosynthetic parameters, oxidative stress markers (O2·-, H2O2, and MDA), antioxidant system (enzymatic--APX, CAT, SOD, GR, DHAR, MDHAR as well as non-enzymatic--AsA and GSH), NO content, and proline metabolism were the key traits that were assessed under different treatments. The P deficiency distinctly declined growth of barley seedlings, which was due to enhancement in oxidative stress leading to inhibition of photosynthesis. These results were also in parallel with an enhancement in antioxidant activity, particularly SOD and CAT, and endogenous proline level and its biosynthetic enzyme (P5CS). The addition of Si exhibited beneficial effects on barley plants grown in Pi-deficient medium as reflected in increased growth, photosynthetic activity, and redox balance through the regulation of antioxidant machinery particularly ascorbate-glutathione cycle. We noticed that auxin and NO were also found to be independently participating in Si-mediated improvement of growth and other parameters in barley roots under Pi deficiency. Data of gene expression analysis for PHOSPHATE TRANSPORTER1 (HvPHT1) indicate that Si helps in increasing Pi uptake as per the need of Pi-deficient barley seedlings, and also auxin and NO both appear to help Si in accomplishing this task probably by inducing lateral root formation. These results are suggestive of possible application of Si as a fertilizer to correct the negative effects of nutritional stresses in plants. Further research at genetic level to understand Si-induced mechanisms for mitigating Pi deficiency can be helpful in the development of new varieties with improved tolerance against Pi deficiency, especially for cultivation in areas with Pi-deficient soils.


Asunto(s)
Hordeum , Ácidos Indolacéticos , Óxido Nítrico , Estrés Oxidativo , Fosfatos , Fotosíntesis , Raíces de Plantas , Silicio , Hordeum/metabolismo , Hordeum/genética , Hordeum/efectos de los fármacos , Hordeum/crecimiento & desarrollo , Hordeum/fisiología , Silicio/farmacología , Silicio/metabolismo , Ácidos Indolacéticos/metabolismo , Fosfatos/deficiencia , Fosfatos/metabolismo , Óxido Nítrico/metabolismo , Raíces de Plantas/metabolismo , Raíces de Plantas/crecimiento & desarrollo , Raíces de Plantas/efectos de los fármacos , Raíces de Plantas/genética , Fotosíntesis/efectos de los fármacos , Antioxidantes/metabolismo , Plantones/crecimiento & desarrollo , Plantones/metabolismo , Plantones/genética , Plantones/efectos de los fármacos , Plantones/fisiología
7.
Opt Express ; 32(10): 16657-16669, 2024 May 06.
Artículo en Inglés | MEDLINE | ID: mdl-38858866

RESUMEN

We demonstrate a single-photon counting Raman spectroscope and benchmark it against conventional and surface-enhanced Raman spectroscopy. For direct comparison without ambiguity, we use the same solutions of Rhodamine 6G and a common optical setup with either a spectrometer or an acousto-optic tunable filter, whereas the surface enhancement is realized with immobilized Ag nanoparticles. Our results find that the single photon counting significantly elevates the detection sensitivity by up to eight orders of magnitude, arriving at a comparable level of surface-enhanced Raman spectroscopy. Another significant advantage is with the time-resolving measurement, where we demonstrate time-gated and time-correlated single-photon counting with sub-nanosecond resolution. It offers insights into the samples' transient responses and enables the isolation of Raman scattering from fluorescence signals.

8.
Opt Express ; 32(10): 17239-17254, 2024 May 06.
Artículo en Inglés | MEDLINE | ID: mdl-38858913

RESUMEN

Doxorubicin (DOX) is an important drug for cancer treatment, but its clinical application is limited due to its toxicity and side effects. Therefore, detecting the concentration of DOX during treatment is crucial for enhancing efficacy and reducing side effects. In this study, the authors developed a biophotonic fiber sensor based on localized surface plasmon resonance (LSPR) with the multimode fiber (MMF)-four core fiber (FCF)-seven core fiber (SCF)-MMF-based direct-taper and anti-taper structures for the specific detection of DOX. Compared to other detection methods, it has the advantages of high sensitivity, low cost, and strong anti-interference ability. In this experiment, multi-walled carbon nanotubes (MWCNTs), cerium-oxide nanorods (CeO2-NRs), and gold nanoparticles (AuNPs) were immobilized on the probe surface to enhance the sensor's biocompatibility. MWCNTs and CeO2-NRs provided more binding sites for the fixation of AuNPs. By immobilizing AuNPs on the surface, the LSPR was stimulated by the evanescent field to detect DOX. The sensor surface was functionalized with DOX aptamers for specific detection, enhancing its specificity. The experiments demonstrated that within a linear detection range of 0-10 µM, the sensitivity of the sensor is 0.77 nm/µM, and the limit of detection (LoD) is 0.42 µM. Additionally, the probe's repeatability, reproducibility, stability, and selectivity were evaluated, indicating that the probe has high potential for detecting DOX during cancer treatment.


Asunto(s)
Doxorrubicina , Oro , Nanopartículas del Metal , Resonancia por Plasmón de Superficie , Doxorrubicina/farmacología , Humanos , Resonancia por Plasmón de Superficie/instrumentación , Oro/química , Nanopartículas del Metal/química , Neoplasias/tratamiento farmacológico , Nanotubos de Carbono/química , Técnicas Biosensibles/instrumentación , Fibras Ópticas , Diseño de Equipo , Antibióticos Antineoplásicos/análisis , Cerio/química , Tecnología de Fibra Óptica/instrumentación
9.
Opt Express ; 32(10): 18087-18098, 2024 May 06.
Artículo en Inglés | MEDLINE | ID: mdl-38858973

RESUMEN

In this paper, a highly sensitive sensor consisting of a silicon nanorod and symmetric rings (SNSR) is presented. Theoretically, three Fano resonances with high Q-factors are excited in the near-infrared range by breaking the symmetry structure based on quasi-bound states in the continuum (Q-BICs). The electromagnetic near-field analysis confirms that the resonances are mainly controlled by toroidal dipole (TD) resonance. The structure is optimized by adjusting different geometrical parameters, and the maximum Q-factor of the Fano resonances can reach 7427. To evaluate the sensing performance of the structure, the sensitivity and the figure of merit (FOM) are calculated by adjusting the environmental refractive index: the maximum sensitivity of 474 nm/RIU and the maximum FOM of 3306 RIU-1. The SNSR can be fabricated by semiconductor-compatible processes, which is experimentally evaluated for changes in transmission spectra at different solution concentrations. The results show that the sensitivity and the Q-factor of the designed metasurface can reach 295 nm/RIU and 850, while the FOM can reach 235 RIU-1. Therefore, the metasurface of SNSR is characterized by high sensitivity and multi-wavelength sensing, which are current research hotspots in the field of optics and can be applied to biomedical sensing and multi-target detection.

10.
Opt Express ; 32(6): 10077-10092, 2024 Mar 11.
Artículo en Inglés | MEDLINE | ID: mdl-38571228

RESUMEN

Every year, millions of people suffer some form of illness associated with the consumption of contaminated food. Escherichia coli (E. coli), found in the intestines of humans and other animals, is commonly associated with various diseases, due to the existence of pathogenic strains. Strict monitoring of food products for human consumption is essential to ensure public health, but traditional cell culture-based methods are associated with long waiting times and high costs. New approaches must be developed to achieve cheap, fast, and on-site monitoring. Thus, in this work, we developed optical fiber sensors based on surface plasmon resonance. Gold and cysteamine-coated fibers were functionalized with anti-E. coli antibody and tested using E. coli suspensions with concentrations ranging from 1 cell/mL to 105 cells/mL. An average logarithmic sensitivity of 0.21 ± 0.01 nm/log(cells/mL) was obtained for three independent assays. An additional assay revealed that including molybdenum disulfide resulted in an increase of approximately 50% in sensitivity. Specificity and selectivity were also evaluated, and the sensors were used to analyze contaminated water samples, which verified their promising applicability in the aquaculture field.


Asunto(s)
Técnicas Biosensibles , Resonancia por Plasmón de Superficie , Animales , Humanos , Resonancia por Plasmón de Superficie/métodos , Escherichia coli , Fibras Ópticas , Técnicas Biosensibles/métodos , Inmunoensayo
11.
Helicobacter ; 29(2): e13069, 2024.
Artículo en Inglés | MEDLINE | ID: mdl-38516860

RESUMEN

Helicobacter pylori (H. pylori) seems to play causative roles in gastric cancers. H. pylori has also been detected in established gastric cancers. How the presence of H. pylori modulates immune response to the cancer is unclear. The cytotoxicity of natural killer (NK) cells, toward infected or malignant cells, is controlled by the repertoire of activating and inhibitory receptors expressed on their surface. Here, we studied H. pylori-induced changes in the expression of ligands, of activating and inhibitory receptors of NK cells, in the gastric adenocarcinoma AGS cells, and their impacts on NK cell responses. AGS cells lacked or had low surface expression of the class I major histocompatibility complex (MHC-I) molecules HLA-E and HLA-C-ligands of the major NK cell inhibitory receptors NKG2A and killer-cell Ig-like receptor (KIR), respectively. However, AGS cells had high surface expression of ligands of activating receptors DNAM-1 and CD2, and of the adhesion molecules LFA-1. Consistently, AGS cells were sensitive to killing by NK cells despite the expression of inhibitory KIR on NK cells. Furthermore, H. pylori enhanced HLA-C surface expression on AGS cells. H. pylori infection enhanced HLA-C protein synthesis, which could explain H. pylori-induced HLA-C surface expression. H. pylori infection enhanced HLA-C surface expression also in the hepatoma Huh7 and HepG2 cells. Furthermore, H. pylori-induced HLA-C surface expression on AGS cells promoted inhibition of NK cells by KIR, and thereby protected AGS cells from NK cell cytotoxicity. These results suggest that H. pylori enhances HLA-C expression in host cells and protects them from the cytotoxic attack of NK cells expressing HLA-C-specific inhibitory receptors.


Asunto(s)
Adenocarcinoma , Infecciones por Helicobacter , Helicobacter pylori , Neoplasias Gástricas , Humanos , Adenocarcinoma/genética , Adenocarcinoma/microbiología , Adenocarcinoma/patología , Infecciones por Helicobacter/genética , Infecciones por Helicobacter/patología , Helicobacter pylori/metabolismo , Antígenos de Histocompatibilidad Clase I/metabolismo , Antígenos HLA-C/genética , Antígenos HLA-C/metabolismo , Células Asesinas Naturales/metabolismo , Células Asesinas Naturales/patología , Receptores Inmunológicos/metabolismo , Receptores KIR/metabolismo , Neoplasias Gástricas/genética , Neoplasias Gástricas/microbiología , Neoplasias Gástricas/patología
12.
Arterioscler Thromb Vasc Biol ; 43(7): 1234-1250, 2023 07.
Artículo en Inglés | MEDLINE | ID: mdl-37259865

RESUMEN

BACKGROUND: TSP1 (thrombospondin-1)-a well-known angiogenesis inhibitor-mediates differential effects via interacting with cell surface receptors including CD36 (cluster of differentiation) and CD47. However, the role of TSP1 in regulating lymphangiogenesis is not clear. Our previous study suggested the importance of cell-specific CD47 blockade in limiting atherosclerosis. Further, our experiments revealed CD47 as a dominant TSP1 receptor in lymphatic endothelial cells (LECs). As the lymphatic vasculature is functionally linked to atherosclerosis, we aimed to investigate the effects of LEC TSP1-CD47 signaling inhibition on lymphangiogenesis and atherosclerosis. METHODS: Murine atherosclerotic and nonatherosclerotic arteries were utilized to investigate TSP1 expression using Western blotting and immunostaining. LEC-specific knockout mice were used to determine the in vivo role of LEC Cd47 in lymphangiogenesis and atherosclerosis. Various in vitro cell-based assays, in vivo Matrigel plug implantation, molecular biological techniques, and immunohistological approaches were used to evaluate the underlying signaling mechanisms. RESULTS: Elevated TSP1 expression was observed in mouse atherosclerotic aortic tissue compared with nonatherosclerotic control tissue. TSP1 at pathological concentrations suppressed both in vitro and in vivo lymphangiogenesis. Mechanistically, TSP1 inhibited VEGF (vascular endothelial growth factor)-C-induced AKT and eNOS activation in LEC and attenuated NO (nitric oxide) production. Further, CD47 silencing in LEC prevented the effects of TSP1 on lymphangiogenic AKT-eNOS signaling and lymphangiogenesis. Atheroprone AAV (adeno-associated virus) 8-PCSK9-injected LEC-specific Cd47 knockout mice (Cd47ΔLEC) had reduced atherosclerosis in both aorta and aortic root compared with control mice (Cd47ΔWT). However, no differences in metabolic parameters including body weight, plasma total cholesterol levels, and fasting blood glucose were observed. Additional immunostaining experiments performed on aortic root cross-sections indicated higher lymphatic vessel density in Cd47ΔLEC mice in comparison to controls. CONCLUSIONS: These findings demonstrate that TSP1 inhibits lymphangiogenesis via activation of CD47 in LEC, and loss of LEC Cd47 attenuates atherosclerotic lesion formation. Collectively, these results identify LEC CD47 as a potential therapeutic target in atherosclerosis.


Asunto(s)
Aterosclerosis , Células Endoteliales , Animales , Ratones , Aterosclerosis/genética , Aterosclerosis/prevención & control , Aterosclerosis/metabolismo , Antígeno CD47/genética , Antígeno CD47/metabolismo , Células Endoteliales/metabolismo , Linfangiogénesis , Ratones Noqueados , Proproteína Convertasa 9/metabolismo , Proteínas Proto-Oncogénicas c-akt/metabolismo , Trombospondina 1/genética , Trombospondina 1/metabolismo , Factor A de Crecimiento Endotelial Vascular/metabolismo
13.
Mol Biol Rep ; 51(1): 804, 2024 Jul 13.
Artículo en Inglés | MEDLINE | ID: mdl-39001960

RESUMEN

Schizophrenia is a neuropsychiatric disorder characterized by various symptoms such as hallucinations, delusions, and disordered thinking. The etiology of this disease is unknown; however, it has been linked to many microdeletion syndromes that are likely to contribute to the pathology of schizophrenia. In this review we have comprehensively analyzed the role of various microdeletion syndromes, like 3q29, 15q13.3, and 22q11.2, which are known to be involved with schizophrenia. A variety of factors lead to schizophrenia phenotypes, but copy number variants that disrupt gene regulation and impair brain function and cognition are one of the causes that have been identified. Multiple case studies have shown that loss of one or more genes in the microdeletion regions lead to brain activity defects. In this article, we present a coherent paradigm that connects copy number variations (CNVs) to numerous neurological and behavioral abnormalities associated with schizophrenia. It would be helpful in understanding the different aspects of the microdeletions and how they contribute in the pathophysiology of schizophrenia.


Asunto(s)
Deleción Cromosómica , Variaciones en el Número de Copia de ADN , Esquizofrenia , Humanos , Esquizofrenia/genética , Variaciones en el Número de Copia de ADN/genética , Fenotipo , Cromosomas Humanos Par 15/genética , Predisposición Genética a la Enfermedad , Discapacidad Intelectual/genética , Trastornos de los Cromosomas/genética , Discapacidades del Desarrollo , Cromosomas Humanos Par 3 , Convulsiones
14.
Phys Chem Chem Phys ; 26(17): 13287-13299, 2024 May 01.
Artículo en Inglés | MEDLINE | ID: mdl-38639091

RESUMEN

Copper iodide, an environmentally friendly material abundant in nature, holds great significance for room temperature thermoelectric (TE) applications owing to its high Seebeck coefficient and optical transparency. However, to fully unlock its thermoelectric potential and match the performance of conventional TE materials, there is a need to further enhance its electrical conductivity. In this study, we have successfully synthesized nano-crystalline powders of both undoped and aluminium-doped CuI at room temperature using the chemical precipitation method in an ethanol medium. The concentration of aluminium dopant has been optimized to maximize TE performance. At 400 K, the highest TE power factor and figure of merit achieved are 79 µW m-1 K-2 and 0.08, respectively, for CuI doped with 0.1 mol% Al. This enhancement in TE properties can be attributed to the increased carrier density resulting from aluminium doping. The impact of aluminium doping on the temperature-dependent thermal conductivity has been investigated, and the findings are explained by the decay mechanism of optical phonons, supported by the anharmonic phonon coupling theory. Our work delves into the evolution of structural, thermal, optical, and TE properties of CuI upon aluminium (Al) doping. The results provide valuable insights into the future application of CuI in transparent thermoelectric and optoelectronic fields.

15.
Mol Cell ; 62(1): 21-33, 2016 Apr 07.
Artículo en Inglés | MEDLINE | ID: mdl-27058785

RESUMEN

The inhibitory function of killer cell immunoglobulin-like receptors (KIR) that bind HLA-C and block activation of human natural killer (NK) cells is dependent on zinc. We report that zinc induced the assembly of soluble KIR into filamentous polymers, as detected by electron microscopy, which depolymerized after zinc chelation. Similar KIR filaments were isolated from lysates of cells treated with zinc, and membrane protrusions enriched in zinc were detected on whole cells by scanning electron microscopy and imaging mass spectrometry. Two independent mutations in the extracellular domain of KIR, away from the HLA-C binding site, impaired zinc-driven polymerization and inhibitory function. KIR filaments formed spontaneously, without the addition of zinc, at functional inhibitory immunological synapses of NK cells with HLA-C(+) cells. Adding to the recent paradigm of signal transduction through higher order molecular assemblies, zinc-induced polymerization of inhibitory KIR represents an unusual mode of signaling by a receptor at the cell surface.


Asunto(s)
Células Asesinas Naturales/inmunología , Receptores KIR/química , Receptores KIR/metabolismo , Zinc/farmacología , Células Cultivadas , Células HEK293 , Antígenos HLA/metabolismo , Humanos , Sinapsis Inmunológicas/metabolismo , Polimerizacion , Receptores KIR/genética , Transducción de Señal
16.
Proc Natl Acad Sci U S A ; 118(32)2021 08 10.
Artículo en Inglés | MEDLINE | ID: mdl-34349021

RESUMEN

The regulator of capsule synthesis (Rcs) is a complex signaling cascade that monitors gram-negative cell envelope integrity. The outer membrane (OM) lipoprotein RcsF is the sensory component, but how RcsF functions remains elusive. RcsF interacts with the ß-barrel assembly machinery (Bam) complex, which assembles RcsF in complex with OM proteins (OMPs), resulting in RcsF's partial cell surface exposure. Elucidating whether RcsF/Bam or RcsF/OMP interactions are important for its sensing function is challenging because the Bam complex is essential, and partial loss-of-function mutations broadly compromise the OM biogenesis. Our recent discovery that, in the absence of nonessential component BamE, RcsF inhibits function of the central component BamA provided a genetic tool to select mutations that specifically prevent RcsF/BamA interactions. We employed a high-throughput suppressor screen to isolate a collection of such rcsF and bamA mutants and characterized their impact on RcsF/OMP assembly and Rcs signaling. Using these mutants and BamA inhibitors MRL-494L and darobactin, we provide multiple lines of evidence against the model in which RcsF senses Bam complex function. We show that Rcs activation in bam mutants results from secondary OM and lipopolysaccharide defects and that RcsF/OMP assembly is required for this activation, supporting an active role of RcsF/OMP complexes in sensing OM stress.


Asunto(s)
Proteínas de la Membrana Bacteriana Externa/metabolismo , Proteínas de Escherichia coli/química , Proteínas de Escherichia coli/metabolismo , Complejos Multiproteicos/metabolismo , Cápsulas Bacterianas/metabolismo , Proteínas de la Membrana Bacteriana Externa/química , Proteínas de la Membrana Bacteriana Externa/genética , Proteínas de Escherichia coli/genética , Regulación Bacteriana de la Expresión Génica , Genes Supresores , Ensayos Analíticos de Alto Rendimiento , Lipopolisacáridos/metabolismo , Complejos Multiproteicos/genética , Mutación , Fenilpropionatos/farmacología
17.
Chaos ; 34(3)2024 Mar 01.
Artículo en Inglés | MEDLINE | ID: mdl-38470261

RESUMEN

Multifractal analysis is a powerful approach for characterizing ergodic or localized nature of eigenstates in complex quantum systems. In this context, the eigenvectors of random matrices belonging to invariant ensembles naturally serve as models for ergodic states. However, it has been found that the finite-size versions of multifractal dimensions for these eigenvectors converge to unity logarithmically slowly with increasing system size N. In fact, this strong finite-size effect is capable of distinguishing the ergodicity behavior of orthogonal and unitary invariant classes. Motivated by this observation, in this work, we provide semi-analytical expressions for the ensemble-averaged multifractal dimensions associated with eigenvectors in the orthogonal-to-unitary crossover ensemble. Additionally, we explore shifted and scaled variants of multifractal dimensions, which, in contrast to the multifractal dimensions themselves, yield distinct values in the orthogonal and unitary limits as N→∞ and, therefore, may serve as a convenient measure for studying the crossover. We substantiate our results using Monte Carlo simulations of the underlying crossover random matrix model. We then apply our results to analyze the multifractal dimensions in a quantum kicked rotor, a Sinai billiard system, and a correlated spin-chain model in a random field. The orthogonal-to-unitary crossover in these systems is realized by tuning relevant system parameters, and we find that in the crossover regime, the observed finite-dimension multifractal dimensions can be captured very well with our results.

18.
Int J Phytoremediation ; 26(8): 1193-1211, 2024 Jun.
Artículo en Inglés | MEDLINE | ID: mdl-38226539

RESUMEN

In this work, green method to synthesize chromium-doped zinc oxide (ZnO) nanorods (NRs) using an aqueous flower extract from Rhododendron arboretum is explored. Herein, chromium-doped ZnO NRs were prepared with different amount of chromium doping, varied as 2-10%. The green synthesized products underwent substantial analysis through X-ray diffraction (XRD), spectroscopic such as ultraviolet spectroscopy(UV-Vis) and scanning electron microscopy (SEM) methods. All samples were found to have hexagonal wurtzite ZnO, with average particle sizes of 52.41, 56.6, 54.44, 53.05, and 56.99 nm, respectively, for 2, 4, 6, 8, and 10% chromium doping in ZnO NRs. The Cr-doped ZnO NRs exhibited remarkable photocatalytic degradation activity of cationic dyes under UV-light, i.e., Malachite Green and Fuchsin Basic with degradation of 99.604 and 99.881%, respectively in 90 min. The reusability tests for these green synthesized Cr-doped ZnO NRs have also been carried out, showed 9-11 cycles with 85% of degradation efficiency. In addition, the Cr-doped ZnO NRs exhibited high selectivity for cationic dyes when experiments against mixture of dyes were performed. Photodegradation kinetics followed the pseudo-first-order model. The flower-extract-stabilized chromium-doped ZnO NRs demonstrated high photocatalytic activity toward malachite green and fuchsin basic dyes, potential material for pollution remediation.


Cr-doped ZnO NRs by green method using flower extract of Rhododendon arboretum were prepared for the first time under ambient reaction conditions.Effect of Dopant i.e. Cr on Photocatalytic activity have been exploited.Selective photocatalytic degradation of cationic dyes i.e. MG, and FB has been achieved in 60­90 minutes.Optimization of reaction condition and various parameters has also been carried out.Recyclability of Cr-doped ZnO NRs was also evaluated and were found to be reusable for 11 cycles for degradation.


Asunto(s)
Cromo , Flores , Nanotubos , Extractos Vegetales , Rhododendron , Colorantes de Rosanilina , Óxido de Zinc , Nanotubos/química , Cromo/química , Colorantes de Rosanilina/química , Flores/química , Extractos Vegetales/química , Óxido de Zinc/química , Rhododendron/química , Tecnología Química Verde , Biodegradación Ambiental , Catálisis , Colorantes/química , Fotólisis , Contaminantes Químicos del Agua/química
19.
Sensors (Basel) ; 24(12)2024 Jun 18.
Artículo en Inglés | MEDLINE | ID: mdl-38931726

RESUMEN

This article shows an all-dielectric metasurface consisting of "H"-shaped silicon disks with tilted splitting gaps, which can detect the temperature and refractive index (RI). By introducing asymmetry parameters that excite the quasi-BIC, there are three distinct Fano resonances with nearly 100% modulation depth, and the maximal quality factor (Q-factor) is over 104. The predominant roles of different electromagnetic excitations in three distinct modes are demonstrated through near-field analysis and multipole decomposition. A numerical analysis of resonance response based on different refractive indices reveals a RI sensitivity of 262 nm/RIU and figure of merit (FOM) of 2183 RIU-1. This sensor can detect temperature fluctuations with a temperature sensitivity of 59.5 pm/k. The proposed metasurface provides a novel method to induce powerful TD resonances and offers possibilities for the design of high-performance sensors.

20.
J Sci Food Agric ; 2024 Jul 20.
Artículo en Inglés | MEDLINE | ID: mdl-39032041

RESUMEN

BACKGROUND: Popcorn is the most popular specialty maize and it makes a significant contribution to the Indian and global economies. Despite perfect exploration of heterosis in field corn, progress in popcorn breeding remains constrained due to its narrow genetic base, leading to a significant dependence on imports. In this study, 15 landrace- and population-derived inbreds from temperate and tropical germplasm were crossed with five testers, which are the parents of superior popcorn hybrids, in a line × tester mating design. RESULTS: Significant variation was observed in popping quality and agronomic traits among crosses evaluated across three locations representing diverse maize-based agro-climatic zones in India. Additive genetic variance governed the traits related to popping quality, whereas dominance variance was responsible for the agronomic traits. In addition to significant heterosis specific to certain traits, we identified promising crosses that exhibited superior performance in both popping quality and grain yield (GY). The genotype + genotype × environment (GGE) biplot methodology identified PMI-PC-104 and PMI-PC-101 as the best discriminating testers for popping quality traits and Dpcl-15-90 for GY. Lines PMI-PC-205, PMI-PC-207, and PMI-PC-209 were the best general combiners for popping quality traits and GY. The heterotic groups identified based on GGE-biplots and the magnitude, direction and stability of combining ability effects would serve in the development of competitive popcorn hybrids for a sustainable popcorn market. CONCLUSION: Using the additive nature of popping quality traits and the dominant nature of GY, recurrent intrapopulation selection can be employed to derive desirable popping quality inbreds with high GY for genetic enhancement. Desirable popping quality alleles from novel germplasm can thus be combined with high-yielding domestic elite inbreds to establish a sustainable popcorn breeding program. © 2024 Society of Chemical Industry.

SELECCIÓN DE REFERENCIAS
DETALLE DE LA BÚSQUEDA