Grayshapiro3966

Heavy metal stress is a major growth- and yield-limiting factor for plants. Heavy metals include essential metals (copper, iron, zinc, and manganese) and non-essential metals (cadmium, mercury, aluminum, arsenic, and lead). Plants use complex mechanisms of gene regulation under heavy metal stress. MicroRNAs are 21-nucleotide non-coding small RNAs as important modulators of gene expression post-transcriptionally. Recently, high-throughput sequencing has led to the identification of an increasing number of heavy-metal-responsive microRNAs in plants. Metal-regulated microRNAs and their target genes are part of a complex regulatory network that controls various biological processes, including heavy metal uptake and transport, protein folding and assembly, metal chelation, scavenging of reactive oxygen species, hormone signaling, and microRNA biogenesis. In this review, we summarize the recent molecular studies that identify heavy-metal-regulated microRNAs and their roles in the regulation of target genes as part of the microRNA-associated regulatory network in response to heavy metal stress in plants.The semicrystalline protein structure and impressive mechanical properties of major ampullate (MA) spider silk make it a promising natural alternative to polyacrylonitrile (PAN) fibers for carbon fiber manufacture. However, when annealed using a similar procedure to carbon fiber production, the tensile strength and Young's modulus of MA silk decrease. Despite this, MA silk fibers annealed at 600 °C remain stronger and tougher than similarly annealed PAN but have a lower Young's modulus. Although MA silk and PAN graphitize to similar extents, annealing disrupts the hydrogen bonding that controls crystal alignment within MA silk. Consequently, unaligned graphite crystals form in annealed MA silk, causing it to weaken, while graphite crystals in PAN maintain alignment along the fiber axis, strengthening the fibers. These shortcomings of spider silk when annealed provide insights into the selection and design of future alternative carbon fiber precursors.Ambient desorption/ionization (ADI) sources coupled to mass spectrometer have gained increasing interest in the field of analytical chemistry for its fast and direct analysis of samples. Among many ADI sources, plasma-based ADI sources are an important branch. Despite its extensive use in mass spectrometry analysis, the ionization mechanism of these sources still remain uncertain. The study on ionization mechanism is of great significance to optimize the design of ion sources and to improve ionization efficiency. In this study, targeted research on a better understanding of afterglow distance effects on ionization process was conducted. Based on the quantified signal expression of reagent ions in mass spectrum, the concept that optimal atmospheric analysis distance of plasma ADI source is defined for the first time. From the perspective of mutual restriction effect between atmospheric components, the formation progress of reagent ions was visually revealed in detail, which involved the initial step of forming precursor reagent ions, the clusters reaction for increasing production of reagent ions, and the matrix effect results in reagent ion depletion. The formation mechanism of reagent ions further clarified the explicit reason for abundant reagent ions generated at an optimal distance. Most importantly, the analyte analysis results verified the significant impact of appropriate distance on ionization efficiency in afterglow region. It was confirmed that the quantity and type of reagent ions intimately influenced the status of analyte ions in mass spectrum.Here we report a synthetic protocol toward a merocyanine (MC) pentamer 1 which represents the first merocyanine oligomer longer than a dimer. By continuously decreasing the solvent polarity, we demonstrate the stepwise folding from partially folded monomeric and dimeric MC subunits (in chloroform) up to the full pentamer π-stack (in 75% methylcyclohexane/25% chloroform) and a subsequent self-assembly of pentamer 1 into larger aggregates (in 80% methylcyclohexane/20% chloroform). This hierarchical structure formation process became possible due to the predominant dipole-dipole interactions among MC dyes that allowed for a precise modulation of the energy landscape by the solvent polarity. This unprecedented stepwise control of dye assembly via hierarchical dipole-dipole interactions opens the door for a more precise control of dye-dye interactions in artificial multichromophoric ensembles.TDP-43 is a primary pathological hallmark protein of amyotrophic lateral sclerosis and frontotemporal lobar degeneration, which may exist in the form of amyloid inclusions in the cells of patients. In addition to serving as a biomarker for these diseases, TDP-43 can also directly trigger neurodegeneration. We previously determined the amyloidogenic core region of TDP-43 (residues 311-360) and showed by solution NMR that this region includes two α-helices [(321-330) and (335-343)] in solution. We suggested that the helix-to-sheet structural transformation initiates TDP-43 aggregation. In the present study, X-ray diffraction shows that TDP-43 (311-360) aggregates adopt a cross-β structure. Thioredoxin (Trx)-fused TDP-43 (311-360) can undergo liquid-liquid phase separation (LLPS) before fibrillation, suggesting that phase separation is an intermediate step before amyloid formation. Solid-state NMR (SSNMR), carried out to elucidate the structural changes of TDP-43 (311-360) at the atomic level, indicates five β-strands of the amyloids formed, with the major two β-strands contributed by the first helical region in the solution structure. The NMR evidence is also in support of the fibril having a parallel in-register conformation, implying a mechanism in which the helix-helix interactions in LLPS are converted into β-strand parallel lateral association upon fibrillation. Our studies have assigned many key interresidue interactions that contribute to the stability of the fibril, including F316 with I318 and Q327 and W334 with A325, A326, A329, and S332. SSNMR with 1H detection reveals a unique close interaction between the indole Nε1-Hε1 of W334 and the side-chain carbonyl of Q343. This interaction could be a very important factor in initiating TDP-43 (311-360) folding/misfolding in LLPS.Top-down mass spectrometry (MS) is an increasingly important technique for protein characterization. However, in many biological MS experiments, the practicality of applying top-down methodologies is still limited at higher molecular mass. In large part, this is due to the detrimental effect resulting from the partitioning of the mass spectral signal into an increasing number of isotopic peaks as molecular mass increases. Reducing the isotopologue distribution of proteins via depletion of heavy stable isotopes was first reported over 20 years ago (Marshall, A. G.; Senko, M. W.; Li, W.; Li, M.; Dillon, S., Guan, S.; Logan, T. M.. Protein Molecular Mass to 1 Da by 13C, 15N Double-Depletion and FT-ICR Mass Spectrometry. J. Am. Chem. MDV3100 Soc. 1997, 119, 433-434.) and has been demonstrated for several small proteins. Here we extend this approach, introducing a new highly efficient method for the production of recombinant proteins depleted in 13C and 15N and demonstrating its advantages for top-down analysis of larger proteins (up to ∼50 kDa). FT-ICR MS of isotopically depleted proteins reveals dramatically reduced isotope distributions with monoisotopic signal observed up to 50 kDa. In top-down fragmentation experiments, the reduced spectral complexity alleviates fragment-ion signal overlap, the presence of monoisotopic signals allows assignment with higher mass accuracy, and the dramatic increase in signal-to-noise ratio (up to 7-fold) permits vastly reduced acquisition times. These compounding benefits allow the assignment of ∼3-fold more fragment ions than comparable analyses of proteins with natural isotopic abundances. Finally, we demonstrate greatly increased sequence coverage in time-limited top-down experiments-highlighting advantages for top-down LC-MS/MS workflows and top-down proteomics.This study analyzes and evaluates the use of cellulose nanocrystals (CNCs), stiff nanosized natural materials that have been modified to mimic heparin. These CNCs are simple polysaccharides with a similar backbone structure to heparin, which when modified reduces coagulation and potentially the long-term effects of solution-based anticoagulants. Thus, CNCs represent an ideal foundation for generating materials biocompatible with blood. In this study, we developed a biocompatible material that inhibits blood clotting through surface functionalization to mimic heparin. Surface chemistry of CNCs was modified from "plain" CNCs (70 mmol SO3-/kg) to 500 mmol COO-/kg (TEMPO-oxidized CNCs) and 330 mmol SO3-/kg CNCs (sulfonated CNCs). Platelet adherence and blood assays show that changes in functionalization reduce coagulation. By utilizing and modifying CNCs reactive functional groups, we create a material with unique and favorable mechanical properties while also reducing clotting.The ability of mixing colors with remarkable results had long been exclusive to the talents of master painters. By finely combining colors in different amounts on the palette, intuitively, they obtain smooth gradients with any given color. Creating such smooth color variations through scattering by the structural patterning of a surface, as opposed to color pigments, has long remained a challenge. Here, we borrow from the painter's approach and demonstrate color mixing generated by an optical metasurface. We propose a single-layer plasmonic color pixel and a method for nanophotonic structural color mixing based on the additive red-green-blue (RGB) color model. The color pixels consist of plasmonic nanorod arrays that generate vivid primary colors and enable independent control of color brightness without affecting chromaticity by simply varying geometric in-plane parameters. link2 By interleaving different nanorod arrays, we combine up to three primary colors on a single pixel. Based on this, two- and three-color mixing is demonstrated, enabling the continuous coverage of a plasmonic RGB color gamut and yielding a palette with a virtually unlimited number of colors. With this multiresonant color pixel, we show the photorealistic printing of color and monochrome images at the nanoscale, with ultrasmooth transitions in color and brightness. Our color-mixing approach can be applied to a broad range of scatterer designs and materials and has the potential to be used for multiwavelength color filters and dynamic photorealistic displays.Herein, we report hierarchical 3D NiMn-layered double hydroxide (NiMn-LDHs) shells grown on conductive silver nanowire (Ag NWs) cores as efficient, low-cost, and durable oxygen reduction reaction (ORR)/oxygen evolution reaction (OER) bifunctional electrocatalysts for metal-air batteries. The hierarchical 3D architectured Ag NW@NiMn-LDH catalysts exhibit superb OER/ORR activities in alkaline conditions. link3 The outstanding bifunctional activities of Ag NW@NiMn-LDHs are essentially attributed to increasing both site activity and site populations. The synergistic contributions from the hierarchical 3D open-pore structure of the LDH shells, improved electrical conductivity, and small thickness of the LDHs shells are associated with more accessible site populations. Moreover, the charge transfer between Ag cores and metals of LDH shells and the formation of defective and distorted sites (less coordinated Ni and Mn sites) strongly enhance the site activity. Thus, Ag NW@NiMn-LDH hybrids exhibit a 0.75 V overvoltage difference between ORR and OER with excellent durability for 30 h, demonstrating the distinguished bifunctional electrocatalyst reported to date.