BnMs3 is required for tapetal differentiation and degradation, microspore separation, and pollen-wall biosynthesis in Brassica napus

7365AB, a recessive genetic male sterility system, is controlled by BnMs3 in Brassica napus, which encodes a Tic40 protein required for tapetum development. However, the role of BnMs3 in rapeseed anther development is still largely unclear. In this research, cytological analysis revealed that anther development of a Bnms3 mutant has defects in the transition of the tapetum to the secretory type, callose degradation, and pollen-wall formation. A total of 76 down-regulated unigenes in the Bnms3 mutant, several of which are associated with tapetum development, callose degeneration, and pollen development, were isolated by suppression subtractive hybridization combined with a macroarray analysis. Reverse genetics was applied by means of Arabidopsis insertional mutant lines to characterize the function of these unigenes and revealed that MSR02 is only required for transport of sporopollenin precursors through the plasma membrane of the tapetum. The real-time PCR data have further verified that BnMs3 plays a primary role in tapetal differentiation by affecting the expression of a few key transcription factors, participates in tapetal degradation by modulating the expression of cysteine protease genes, and influences microspore separation by manipulating the expression of BnA6 and BnMSR66 related to callose degradation and of BnQRT1 and BnQRT3 required for the primary cell-wall degradation of the pollen mother cell. Moreover, BnMs3 takes part in pollen-wall formation by affecting the expression of a series of genes involved in biosynthesis and transport of sporopollenin precursors. All of the above results suggest that BnMs3 participates in tapetum development, microspore release, and pollen-wall formation in B. napus

Dissecting the neurovascular unit in physiology and Alzheimer's disease: Functions, imaging tools and genetic mouse models

The neurovascular unit (NVU) plays an essential role in regulating neurovascular coupling, which refers to the communication between neurons, glia, and vascular cells to control the supply of oxygen and nutrients in response to neural activity. Cellular elements of the NVU coordinate to establish an anatomical barrier to separate the central nervous system from the milieu of the periphery system, restricting the free movement of substances from the blood to the brain parenchyma and maintaining central nervous system homeostasis. In Alzheimer's disease, amyloid-β deposition impairs the normal functions of NVU cellular elements, thus accelerating the disease progression. Here, we aim to describe the current knowledge of the NVU cellular elements, including endothelial cells, pericytes, astrocytes, and microglia, in regulating the blood-brain barrier integrity and functions in physiology as well as alterations encountered in Alzheimer's disease. Furthermore, the NVU functions as a whole, therefore specific labeling and targeting NVU components in vivo enable us to understand the mechanism mediating cellular communication. We review approaches including commonly used fluorescent dyes, genetic mouse models, and adeno-associated virus vectors for imaging and targeting NVU cellular elements in vivo

Chlorophyll Deficiency in the Maize <i>elongated mesocotyl2</i> Mutant Is Caused by a Defective Heme Oxygenase and Delaying Grana Stacking

<div><p>Background</p><p>Etiolated seedlings initiate grana stacking and chlorophyll biosynthesis in parallel with the first exposure to light, during which phytochromes play an important role. Functional phytochromes are biosynthesized separately for two components. One phytochrome is biosynthesized for apoprotein and the other is biosynthesized for the chromophore that includes heme oxygenase (HO).</p> <p>Methodology/Principal Finding</p><p>We isolated a <i>ho1</i> homolog by map-based cloning of a maize <i>elongated</i><i>mesocotyl2</i> (<i>elm2</i>) mutant. cDNA sequencing of the <i>ho1</i> homolog in <i>elm2</i> revealed a 31 bp deletion. De-etiolation responses to red and far-red light were disrupted in <i>elm2</i> seedlings, with a pronounced elongation of the mesocotyl. The endogenous HO activity in the <i>elm2</i> mutant decreased remarkably. Transgenic complementation further confirmed the dysfunction in the maize <i>ho1</i> gene. Moreover, non-appressed thylakoids were specifically stacked at the seedling stage in the <i>elm2</i> mutant.</p> <p>Conclusion</p><p>The 31 bp deletion in the <i>ho1</i> gene resulted in a decrease in endogenous HO activity and disrupted the de-etiolation responses to red and far-red light. The specific stacking of non-appressed thylakoids suggested that the chlorophyll biosynthesis regulated by <i>HO1</i> is achieved by coordinating the heme level with the regulation of grana stacking.</p> </div

Electron microscope images of chloroplast structures.

<p>A and C, Zheng58 wild-type plants at the seedling and tasseling stages, respectively; B and D, <i>elm2</i> mutant plants at the seedling and tasseling stages, respectively. Scale bar=500 nm.</p

De-etiolation responses in Zheng58 wild-type plants and <i>elm2</i> mutants.

<p>Representative seedlings were photographed after 7 d of growth in continuous darkness (A), white light (B), red light (C), far-red light (D) or blue light (E) conditions. Left, Zheng58 wild-type seedlings; Right, <i>elm2</i> mutants. Scale bar=1 cm.</p

Statistical measurement of mesocotyl length in Zheng58 wild-type plants and <i>elm2</i> mutant plants.

<p>Zheng58 wild-type seedlings and mutant <i>elm2</i> seedlings were grown for 7 d in continuous darkness, white light, red light, far-red light, or blue light conditions. The sample size was 16-18 seedlings per treatment/genotype. Asterisk indicates significant difference as compared with Zheng58 wild-type at <i>P</i><0.01 (Student’s <i>t</i> test).</p

Porous, Platinum Nanoparticle-Adsorbed Carbon Nanotube Yarns for Efficient Fiber Solar Cells

Pt is a classical catalyst that has been extensively used in fuel cell and solar cell electrodes, owing to its high catalytic activity, good conductivity, and stability. In conventional fiber-shaped solar cells, solid Pt wires are usually adopted as the electrode material. Here, we report a Pt nanoparticle-adsorbed carbon nanotube yarn made by solution adsorption and yarn spinning processes, with uniformly dispersed Pt nanoparticles through the porous nanotube network. We have fabricated TiO₂-based dye-sensitized fiber solar cells with a Pt–nanotube hybrid yarn as counter electrode and achieved a power conversion efficiency of 4.85% under standard illumination (AM1.5, 100 mW/cm²), comparable to the same type of fiber cells with a Pt wire electrode (4.23%). Adsorption of Pt nanoparticles within a porous nanotube yarn results in enhanced Pt–electrolyte interfacial area and significantly reduced charge-transfer resistance across the electrolyte interface, compared to a pure nanotube yarn or Pt wire. Our porous Pt–nanotube hybrid yarns have the potential to reduce the use of noble metals, lower the device weight, and improve the solar cell efficiency

Metastable 1T′-phase group VIB transition metal dichalcogenide crystals

Metastable 1T′-phase transition metal dichalcogenides (1T′-TMDs) with semi-metallic natures have attracted increasing interest owing to their uniquely distorted structures and fascinating phase-dependent physicochemical properties. However, the synthesis of high-quality metastable 1T′-TMD crystals, especially for the group VIB TMDs, remains a challenge. Here, we report a general synthetic method for the large-scale preparation of metastable 1T′-phase group VIB TMDs, including WS2, WSe2, MoS2, MoSe2, WS2xSe2(1−x) and MoS2xSe2(1−x). We solve the crystal structures of 1T′-WS2, -WSe2, -MoS2 and -MoSe2 with single-crystal X-ray diffraction. The as-prepared 1T′-WS2 exhibits thickness-dependent intrinsic superconductivity, showing critical transition temperatures of 8.6 K for the thickness of 90.1 nm and 5.7 K for the single layer, which we attribute to the high intrinsic carrier concentration and the semi-metallic nature of 1T′-WS2. This synthesis method will allow a more systematic investigation of the intrinsic properties of metastable TMDs.Agency for Science, Technology and Research (A*STAR)Ministry of Education (MOE)National Research Foundation (NRF)Submitted/Accepted versionH.Z. acknowledges support from ITC via the Hong Kong Branch of National Precious Metals Material Engineering Research Center (NPMM), the Start-Up Grant (project no. 9380100) and grants (project nos. 9610478 and 1886921) from the City University of Hong Kong and the Science Technology and Innovation Committee of Shenzhen Municipality (grant no. JCYJ20200109143412311). Q.H. acknowledges the funding support from the Start-Up Grant (project no. 9610482) from the City University of Hong Kong. Y.S. and Y.M. acknowledge the funding support from the National Natural Science Foundation of China (under grant no. 11534003) and the Program for JLU Science and Technology Innovative Research Team and Science Challenge Project (no. TZ2016001). K.H. and D.V.M.R. acknowledge funding from the Accelerated Materials Development for Manufacturing Program at A*STAR via the AME Programmatic Fund by the Agency for Science, Technology and Research under grant no. A1898b0043. R.V.R. and V.S. acknowledge support by grants from the National Research Foundation, Prime Minister’s Office, Singapore, under its Campus for Research Excellence and Technological Enterprise (CREATE) programme. X.R.W. acknowledges supports from Academic Research Fund Tier 2 (grant no. MOE-T2EP50120-006) from Singapore Ministry of Education