Boundaries occur naturally in kinetic equations, and boundary effects are crucial for dynamics of dilute gases governed by the Boltzmann equation. We develop a mathematical theory to study the time ...decay and continuity of Boltzmann solutions for four basic types of boundary conditions: in-flow, bounce-back reflection, specular reflection and diffuse reflection. We establish exponential decay in the
L
∞
norm for hard potentials for general classes of smooth domains near an absolute Maxwellian. Moreover, in convex domains, we also establish continuity for these Boltzmann solutions away from the grazing set at the boundary. Our contribution is based on a new
L
2
decay theory and its interplay with delicate
L
∞
decay analysis for the linearized Boltzmann equation in the presence of many repeated interactions with the boundary.
Excess soluble salts in soil (saline soils) are harmful to most plants. Salt imposes osmotic, ionic, and secondary stresses on plants. Over the past two decades, many determinants of salt tolerance ...and their regulatory mechanisms have been identified and characterized using molecular genetics and genomics approaches. This review describes recent progress in deciphering the mechanisms controlling ion homeostasis, cell activity responses, and epigenetic regulation in plants under salt stress. Finally, wehighlight research areas that require further research to reveal new determinants of salt tolerance in plants.
Salt stress is a major environmental factor limiting plant growth and productivity. A better understanding of the mechanisms mediating salt resistance will help researchers design ways to improve ...crop performance under adverse environmental conditions. Salt stress can lead to ionic stress, osmotic stress and secondary stresses, particularly oxidative stress, in plants. Therefore, to adapt to salt stress, plants rely on signals and pathways that re‐establish cellular ionic, osmotic, and reactive oxygen species (ROS) homeostasis. Over the past two decades, genetic and biochemical analyses have revealed several core stress signaling pathways that participate in salt resistance. The Salt Overly Sensitive signaling pathway plays a key role in maintaining ionic homeostasis, via extruding sodium ions into the apoplast. Mitogen‐activated protein kinase cascades mediate ionic, osmotic, and ROS homeostasis. SnRK2 (sucrose nonfermenting 1‐related protein kinase 2) proteins are involved in maintaining osmotic homeostasis. In this review, we discuss recent progress in identifying the components and pathways involved in the plant's response to salt stress and their regulatory mechanisms. We also review progress in identifying sensors involved in salt‐induced stress signaling in plants.
Salt stress is the main environmental factor limiting crop productivity. A better understanding of the mechanisms that regulate salt tolerance will help researchers design ways to improve crop performance. In this review, we discuss recent advances in determining the components of plants that respond to salt stress and their regulatory mechanisms.
norms, but can have large high derivatives with high velocity moments. Our construction is based on the accumulative study of the Landau kernel in the past decade, with four extra ingredients to ...overcome the specific mathematical difficulties present in the Vlasov-Poisson-Landau system: a new exponential weight of electric potential to cancel the growth of the velocity, a new velocity weight to capture the weak velocity diffusion in the Landau kernel, a decay of the electric field to close the energy estimate, and a new bootstrap argument to control the propagation of the high moments and regularity with large amplitude.>
Transition metal (TM)‐based bimetallic spinel oxides can efficiently activate peroxymonosulfate (PMS) presumably attributed to enhanced electron transfer between TMs, but the existing model cannot ...fully explain the efficient TM redox cycling. Here, we discover a critical role of TM−O covalency in governing the intrinsic catalytic activity of Co3−xMnxO4 spinel oxides. Experimental and theoretical analysis reveals that the Co sites significantly raises the Mn valence and enlarges Mn−O covalency in octahedral configuration, thereby lowering the charge transfer energy to favor MnOh–PMS interaction. With appropriate MnIV/MnIII ratio to balance PMS adsorption and MnIV reduction, the Co1.1Mn1.9O4 exhibits remarkable catalytic activities for PMS activation and pollutant degradation, outperforming all the reported TM spinel oxides. The improved understandings on the origins of spinel oxides activity for PMS activation may inspire the development of more active and robust metal oxide catalysts.
The Mn−O covalency was enlarged by the Co sites mainly in the octahedral configuration, which results in a decreased charge transfer energy to favor Mn–PMS interaction and enhance MnIV reduction to boost PMS activation activity of Co‐Mn spinel oxides.
Orchidaceae is one of the largest families of angiosperms. Considering the large number of species in this family and its symbiotic relationship with fungi, Orchidaceae provide an ideal model to ...study the evolution of plant mitogenomes. However, to date, there is only one draft mitochondrial genome of this family available. Here, we present a fully assembled and annotated sequence of the mitochondrial genome (mitogenome) of
, a species with high economic and ornamental value. The mitogenome of
was 447,368 bp in length and comprised 26 circular subgenomes ranging in size from 5973 bp to 32,281 bp. The genome encoded for 39 mitochondrial-origin, protein-coding genes; 16 tRNAs (three of plastome origin); three rRNAs; and 16 ORFs, while
and
were lost from the mitogenome. Moreover, interorganellar DNA transfer was identified in 14 of the 26 chromosomes. These plastid-derived DNA fragments represented 28.32% (46,273 bp) of the
plastome, including 12 intact plastome origin genes. Remarkably, the mitogenome of
and
shared 18% (about 81 kb) of their mitochondrial DNA sequences. Additionally, we found a positive correlation between repeat length and recombination frequency. The mitogenome of
had more compact and fragmented chromosomes compared to other species with multichromosomal structures. We suggest that repeat-mediated homologous recombination enables the dynamic structure of mitochondrial genomes in Orchidaceae.
MutS homolog 1 (MSH1) is involved in the recombining and repairing of organelle genomes and is essential for maintaining their stability. Previous studies indicated that the length of the gene varied ...greatly among species and detected species-specific partial gene duplications in Physcomitrella patens. However, there are critical gaps in the understanding of the gene size expansion, and the extent of the partial gene duplication of MSH1 remains unclear. Here, we screened MSH1 genes in 85 selected species with genome sequences representing the main clades of green plants (Viridiplantae). We identified the MSH1 gene in all lineages of green plants, except for nine incomplete species, for bioinformatics analysis. The gene is a singleton gene in most of the selected species with conserved amino acids and protein domains. Gene length varies greatly among the species, ranging from 3234 bp in Ostreococcus tauri to 805,861 bp in Cycas panzhihuaensis. The expansion of MSH1 repeatedly occurred in multiple clades, especially in Gymnosperms, Orchidaceae, and Chloranthus spicatus. MSH1 has exceptionally long introns in certain species due to the gene length expansion, and the longest intron even reaches 101,025 bp. And the gene length is positively correlated with the proportion of the transposable elements (TEs) in the introns. In addition, gene structure analysis indicated that the MSH1 of green plants had undergone parallel intron gains and losses in all major lineages. However, the intron number of seed plants (gymnosperm and angiosperm) is relatively stable. All the selected gymnosperms contain 22 introns except for Gnetum montanum and Welwitschia mirabilis, while all the selected angiosperm species preserve 21 introns except for the ANA grade. Notably, the coding region of MSH1 in algae presents an exceptionally high GC content (47.7% to 75.5%). Moreover, over one-third of the selected species contain species-specific partial gene duplications of MSH1, except for the conserved mosses-specific partial gene duplication. Additionally, we found conserved alternatively spliced MSH1 transcripts in five species. The study of MSH1 sheds light on the evolution of the long genes of green plants.
The application of metal–organic frameworks (MOFs) as SERS‐active platforms in multiplex volatile organic compounds (VOCs) detection is still unexplored. Herein, we demonstrate that MIL‐100 (Fe) ...serves as an ideal SERS substrate for the detection of VOCs. The limit of detection (LOD) of MIL‐100(Fe) for toluene sensing can reach 2.5 ppm, and can be even further decreased to 0.48 ppb level when “hot spots” in between Au nanoparticles are employed onto MIL‐100 (Fe) substrate, resulting in an enhancement factor of 1010. Additionally, we show that MIL‐100(Fe) substrate has a unique “sensor array” property allowing multiplex VOCs detection, with great modifiability and expandability by doping with foreign metal elements. Finally, the MIL‐100(Fe) platform is utilized to simultaneously detect the different gaseous indicators of lung cancer with a ppm detection limit, demonstrating its high potential for early diagnosis of lung cancer in vivo.
MIL‐100(Fe) is demonstrated to serve as an ideal “SERS‐active” and “sensory array” platform for multiplex sensing of volatile organic compounds (VOCs) as well as the gaseous biomarkers of diseases with low Raman cross‐sections.
Ischemic stroke leads to neuronal damage induced by excitotoxicity, inflammation, and oxidative stress. Astrocytes play diverse roles in stroke and ischemia‐induced inflammation, and autophagy is ...critical for maintaining astrocytic functions. Our previous studies showed that the activation of G protein‐coupled receptor 30 (GPR30), an estrogen membrane receptor, protected neurons from excitotoxicity. However, the role of astrocytic GPR30 in maintaining autophagy and neuroprotection remained unclear. In this study, we found that the neuroprotection induced by G1 (GPR30 agonist) in wild‐type mice after a middle cerebral artery occlusion was completely blocked in GPR30 conventional knockout (KO) mice but partially attenuated in astrocytic or neuronal GPR30 KO mice. In cultured primary astrocytes, glutamate exposure induced astrocyte proliferation and decreased astrocyte autophagy by activating mammalian target of rapamycin (mTOR) and c‐Jun N‐terminal kinase (JNK) and inhibiting p38 mitogen‐activated protein kinase (MAPK) pathway. G1 treatment restored autophagy to its basal level by regulating the p38 pathway but not the mTOR and JNK signaling pathways. Our findings revealed a key role of GPR30 in neuroprotection via the regulation of astrocyte autophagy and support astrocytic GPR30 as a potential drug target against ischemic brain damage.
Main Points
Astrocytic GPR30 was involved in the neuroprotection.
Autophagic deficiency of astrocytes induced by glutamate promoted inflammatory cytokine release.
GPR30 activation restored autophagy balance in astrocytes by regulating the p38 MAPK pathway.
WRKY transcription factors play a key role in the tolerance of biotic and abiotic stresses across various crop species, but the function of some WRKY genes, particularly in tomato, remains ...unexplored. Here, we characterize the roles of a previously unstudied WRKY gene, SlWRKY8, in the resistance to pathogen infection and the tolerance to drought and salt stresses. Expression of SlWRKY8 was up‐regulated upon Pseudomonas syringae pv. tomato DC3000 (Pst. DC3000), abiotic stresses such as drought, salt and cold, as well as ABA and SA treatments. The SlWRKY8 protein was localized to the nucleus with no transcription activation in yeast, but it could activate W‐box‐dependent transcription in plants. The overexpression of SlWRKY8 in tomato conferred a greater resistance to the pathogen Pst. DC3000 and resulted in the increased transcription levels of two pathogen‐related genes SlPR1a1 and SlPR7. Moreover, transgenic plants displayed the alleviated wilting or chlorosis phenotype under drought and salt stresses, with higher levels of stress‐induced osmotic substances like proline and higher transcript levels of the stress‐responsive genes SlAREB, SlDREB2A and SlRD29. Stomatal aperature was smaller under drought stress in transgenic plants, maintaining higher water content in leaves compared with wild‐type plants. The oxidative pressure, indicated by the concentration of hydrogen peroxide (H2O2) and malondialdehyde (MDA), was also reduced in transgenic plants, where we also observed higher levels of antioxidant enzyme activities under stress. Overall, our results suggest that SlWRKY8 functions as a positive regulator in plant immunity against pathogen infection as well as in plant responses to drought and salt stresses.
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