Single-Cell Transcriptome and Network Analyses Unveil Key Transcription Factors Regulating Mesophyll Cell Development in Maize

BACKGROUND: Maize mesophyll (M) cells play important roles in various biological processes such as photosynthesis II and secondary metabolism. Functional differentiation occurs during M-cell development, but the underlying mechanisms for regulating M-cell development are largely unknown. RESULTS: We conducted single-cell RNA sequencing (scRNA-seq) to profile transcripts in maize leaves. We then identified coregulated modules by analyzing the resulting pseudo-time-series data through gene regulatory network analyses. , , , and () families were highly expressed in the early stage, whereas () and families were highly expressed in the late stage of M-cell development. Construction of regulatory networks revealed that these transcript factor (TF) families, especially and , were the major players in the early and later stages of M-cell development, respectively. Integration of scRNA expression matrix with TF ChIP-seq and Hi-C further revealed regulatory interactions between these TFs and their targets. and were primarily expressed in the leaf bases and tips, respectively, and their targets were validated with protoplast-based ChIP-qPCR, with the binding sites of HSF1 being experimentally confirmed. CONCLUSIONS: Our study provides evidence that several TF families, with the involvement of epigenetic regulation, play vital roles in the regulation of M-cell development in maize

Genome sequence and evolution of Betula platyphylla

Betula L. (birch) is a pioneer hardwood tree species with ecological, economic, and evolutionary importance in the Northern Hemisphere. We sequenced the Betula platyphylla genome and assembled the sequences into 14 chromosomes. The Betula genome lacks evidence of recent whole-genome duplication and has the same paleoploidy level as Vitis vinifera and Prunus mume. Phylogenetic analysis of lignin pathway genes coupled with tissue-specific expression patterns provided clues for understanding the formation of higher ratios of syringyl to guaiacyl lignin observed in Betula species. Our transcriptome analysis of leaf tissues under a time-series cold stress experiment revealed the presence of the MEKK1–MKK2–MPK4 cascade and six additional mitogen-activated protein kinases that can be linked to a gene regulatory network involving many transcription factors and cold tolerance genes. Our genomic and transcriptome analyses provide insight into the structures, features, and evolution of the B. platyphylla genome. The chromosome-level genome and gene resources of B. platyphylla obtained in this study will facilitate the identification of important and essential genes governing important traits of trees and genetic improvement of B. platyphylla

Application of metal-organic frameworks, covalent organic frameworks and their derivates for the metal-air batteries

Metal-organic frameworks (MOFs) and covalent organic frameworks (COFs) as the novel porous materials have the merits of diverse, adjustable functionality, high porosity and surface area, which have great application prospects in the gas storage, separation and catalysis. In addition, their derivates make up for the insufficient of electronic conductivity and chemical stability of MOFs and COFs, and provide a new ideal for accurate control of material structure. Up to now, many efficient electrocatalysts have been designed based on MOFs, COFs and their derivates for O2 reduction/evolution reactions (ORR/OER) and CO2 reduction/evolution reactions (CO2RR/CO2ER) in the metal-air batteries. In this review, the latest development of MOFs, COFs and their derivates in the metal-air batteries is summarized, and we discuss the structural characteristics of these materials and their corresponding mechanisms of action. By comprehensively reviewing the advantages, challenges and prospects of MOFs and COFs, we hope that the organic framework materials will shed more profound insights into the development of electrocatalysis and energy storage in the future

The Chinese pine genome and methylome unveil key features of conifer evolution

Conifers dominate the world's forest ecosystems and are the most widely planted tree species. Their giant and complex genomes present great challenges for assembling a complete reference genome for evolutionary and genomic studies. We present a 25.4-Gb chromosome-level assembly of Chinese pine (Pinus tabuliformis) and revealed that its genome size is mostly attributable to huge intergenic regions and long introns with high transposable element (TE) content. Large genes with long introns exhibited higher expressions levels. Despite a lack of recent whole-genome duplication, 91.2% of genes were duplicated through dispersed duplication, and expanded gene families are mainly related to stress responses, which may underpin conifers' adaptation, particularly in cold and/or arid conditions. The reproductive regulation network is distinct compared with angiosperms. Slow removal of TEs with high-level methylation may have contributed to genomic expansion. This study provides insights into conifer evolution and resources for advancing research on conifer adaptation and development

Global Solutions to an initial boundary problem for the compressible 3-D MHD equations with Navier-slip and perfectly conducting boundary conditions in exterior domains

An initial boundary value problem for compressible Magnetohydrodynamics (MHD) is considered on an exterior domain (with the first Betti number vanishes) in $R^3$ in this paper. The global existence of smooth solutions near a given constant state for compressible MHD with the boundary conditions of Navier-slip for the velocity filed and perfect conduction for the magnetic field is established. Moreover the explicit decay rate is given. In particular, the results obtained in this paper also imply the global existence of classical solutions for the full compressible Navier-Stokes equations with Navier-slip boundary conditions on exterior domains in three dimensions, which is not available in literature, to the best of knowledge of the authors'

An Early Stage of Aerosol Particle Transport in Flows Past Periodic Arrays of Clear Staggered Obstructions: A Computational Study

<p>Transport of aerosol particles is a fundamental phenomenon in many environmental and industrial applications. Among the several computational fluid dynamical schemes used to study this problem, the lattice Boltzmann methods (LBMs) have shown great promise. Using a 2-D LBM model coupled with a Lagrangian formalism, this study investigates an early stage of particle–surface collisions in a free-stream flow over a semi-infinite array of staggered obstructions at operating conditions of woven-wire screens. After an initial validation of the model, the particle–surface collision efficiency with different diameters is then examined as functions of the number of staggered obstructions, obstruction morphology, and separation distance between two center points of obstructions. Particle motion mechanisms include drag, lift, and Brownian forces. Enhanced collision efficiency of particles to obstructions due to the presence of multiple staggered cylindrical obstructions is identified and highlighted. Based on these insights, our work also explores the possibility that collision efficiency of particles to obstructions can be enhanced by a change of obstruction morphology. Finally, the results highlight the range where particle–surface collision efficiency is sensitive to the longitudinal spacing between two cylindrical obstructions.</p> <p>Copyright 2014 American Association for Aerosol Research</p

How does iliosacral bone tumor resection without reconstruction affect the ipsilateral hip joint?

Abstract Background Whether reconstruction is more beneficial after iliosacral bone tumor resection remains controversial. Because of high rates of complications and recurrence, few patients benefit from reconstruction. The aim of this study is to assess functional outcomes and to reveal changes in the ipsilateral hip joint after partial iliosacral resection. Methods From 1998 to 2016, 21 patients aged 20–66 years underwent iliosacral resection, 18 without reconstruction (group 1) and 3 with reconstruction (group 2). Function was evaluated using the Musculoskeletal Tumor Society 1993 rating scale (MSTS 1993), and disability was measured using the Toronto Extremity Salvage Score (TESS). I-A distance was defined as the distance from the iliosacral joint to the upper line of the acetabulum along the curved line. Group 1 were subdivided into two groups: group 1A included the patients with a defect less than one-third of the I-A distance and group 1B the remainder. Acetabulum-head index (AHI) and center-edge angle (CE angle) were measured. The relationship between defect length and femoral head coverage was analyzed. Results The mean follow-up was 67.3 months. Eighteen patients were included in group 1 and three in group 2. Preoperative data of the 3 groups were statistically equivalent. In addition, no difference of postoperative functional outcome has been highlighted. The final average MSTS 1993 score was 93.6% in group 1 and 93.3% in group 2. The mean TESS was 98 in group 1 and 98.5 in group 2. AHI and CE angle between groups 1 and 2 were not different. The AHI was 80 ± 5.4% in group 1A and 67 ± 9.0% in group 1B (t = − 3.740, P = 0.002), while the CE angle was 29 ± 5.9° in group 1A and 20 ± 6.3° in group 1B (t = − 3.172, P = 0.006) at the last follow-up. Regarding the limb-length discrepancy, group 1 and 2 were similar whereas group 1A and 1B were statistically different (group 1A: 0.7 ± 0.7 cm; group 2: 2.6 ± 1.0 cm; t = − 4.324, P = 0.001). Conclusions Ilio-sacral resection without reconstruction removing more than one- third of the I-A distance leads to an impairement of the limb-length discrepancy and an increase of the defect of the acetabular coverage without altering the functional outcome. Nevertheless, iliosacral resection without reconstruction could serve as a viable treatment option for pelvic type I-IV tumors