Cross-organ single-cell transcriptome profiling reveals macrophage and dendritic cell heterogeneity in zebrafish.

Tissue-resident macrophages (TRMs) and dendritic cells (DCs) are highly heterogeneous and essential for immunity, tissue regeneration, and homeostasis maintenance. Here, we comprehensively profile the heterogeneity of TRMs and DCs across adult zebrafish organs via single-cell RNA sequencing. We identify two macrophage subsets: pro-inflammatory macrophages with potent phagocytosis signatures and pro-remodeling macrophages with tissue regeneration signatures in barrier tissues, liver, and heart. In parallel, one conventional dendritic cell (cDC) population with prominent antigen presentation capacity and plasmacytoid dendritic cells (pDCs) featured by anti-virus properties are also observed in these organs. Remarkably, in addition to a single macrophage/microglia population with potent phagocytosis capacity, a pDC population and two distinct cDC populations are identified in the brain. Finally, we generate specific reporter lines for in vivo tracking of macrophage and DC subsets. Our study depicts the landscape of TRMs and DCs and creates valuable tools for in-depth study of these cells in zebrafish.

Metaphocytes are IL-22BP-producing cells regulated by ETS transcription factor Spic and essential for zebrafish barrier immunity.

Metaphocytes are tissue-resident macrophage (TRM)/dendritic cell (DC)-like cells of non-hematopoietic origin in zebrafish barrier tissues. One remarkable property of metaphocytes is their ability to capture soluble antigens from the external environment via transepithelial protrusions, a unique function manifested by specialized subpopulations of the TRMs/DCs in mammal barrier tissues. Yet, how metaphocytes acquire myeloid-like cell properties from non-hematopoietic precursors and how they regulate barrier immunity remains unknown. Here, we show that metaphocytes are in situ generated from local progenitors guided by the ETS transcription factor Spic, the deficiency of which results in the absence of metaphocytes. We further document that metaphocytes are the major IL-22BP-producing cells, and the depletion of metaphocytes causes dysregulated barrier immunity that resembles the phenotype of IL-22BP-deficient mice. These findings reveal the ontogeny, development, and function of metaphocytes in zebrafish, which facilitates our understanding of the nature and function of the mammalian TRM/DC counterparts.

Duplex Interpenetrating-Phase FeNiZn and FeNi3 Heterostructure with Low-Gibbs Free Energy Interface Coupling for Highly Efficient Overall Water Splitting.

The sluggish kinetics of both hydrogen evolution reaction (HER) and oxygen evolution reaction (OER) generate the large overpotential in water electrolysis and thus high-cost hydrogen production. Here, multidimensional nanoporous interpenetrating-phase FeNiZn alloy and FeNi3 intermetallic heterostructure is in situ constructed on NiFe foam (FeNiZn/FeNi3@NiFe) by dealloying protocol. Coupling with the eminent synergism among specific constituents and the highly efficient mass transport from integrated porous backbone, FeNiZn/FeNi3@NiFe depicts exceptional bifunctional activities for water splitting with extremely low overpotentials toward OER and HER (η1000 = 367/245 mV) as well as the robust durability during the 400 h testing in alkaline solution. The as-built water electrolyzer with FeNiZn/FeNi3@NiFe as both anode and cathode exhibits record-high performances for sustainable hydrogen output in terms of much lower cell voltage of 1.759 and 1.919 V to deliver the current density of 500 and 1000 mA cm-2 as well long working lives. Density functional theory calculations disclose that the interface interaction between FeNiZn alloy and FeNi3 intermetallic generates the modulated electron structure state and optimized intermediate chemisorption, thus diminishing the energy barriers for hydrogen production in water splitting. With the merits of fine performances, scalable fabrication, and low cost, FeNiZn/FeNi3@NiFe holds prospective application potential as the bifunctional electrocatalyst for water splitting.

Endothelial hyperactivation of mutant MAP3K3 induces cerebral cavernous malformation enhanced by PIK3CA GOF mutation.

Cerebral cavernous malformations (CCMs) refer to a common vascular abnormality that affects up to 0.5% of the population. A somatic gain-of-function mutation in MAP3K3 (p.I441M) was recently reported in sporadic CCMs, frequently accompanied by somatic activating PIK3CA mutations in diseased endothelium. However, the molecular mechanisms of these driver genes remain elusive. In this study, we performed whole-exome sequencing and droplet digital polymerase chain reaction to analyze CCM lesions and the matched blood from sporadic patients. 44 of 94 cases harbored mutations in KRIT1/CCM2 or MAP3K3, of which 75% were accompanied by PIK3CA mutations (P = 0.006). AAV-BR1-mediated brain endothelial-specific MAP3K3I441M overexpression induced CCM-like lesions throughout the brain and spinal cord in adolescent mice. Interestingly, over half of lesions disappeared at adulthood. Single-cell RNA sequencing found significant enrichment of the apoptosis pathway in a subset of brain endothelial cells in MAP3K3I441M mice compared to controls. We then demonstrated that MAP3K3I441M overexpression activated p38 signaling that is associated with the apoptosis of endothelial cells in vitro and in vivo. In contrast, the mice simultaneously overexpressing PIK3CA and MAP3K3 mutations had an increased number of CCM-like lesions and maintained these lesions for a longer time compared to those with only MAP3K3I441M. Further in vitro and in vivo experiments showed that activating PI3K signaling increased proliferation and alleviated apoptosis of endothelial cells. By using AAV-BR1, we found that MAP3K3I441M mutation can provoke CCM-like lesions in mice and the activation of PI3K signaling significantly enhances and maintains these lesions, providing a preclinical model for the further mechanistic and therapeutic study of CCMs.

Bioactive graphene oxide-functionalized self-expandable hydrophilic and osteogenic nanocomposite for orthopaedic applications.

Polymethyl methacrylate (PMMA) bone cement (PBC) is commonly used in orthopaedic surgery. However, polymerization volumetric shrinkage, exothermic injury, and low bioactivity prevent PBC from being an ideal material. The developed expandable P(MMA-AA-St) well overcomes the volumetric shrinkage of PBC. However, its biomechanical properties are unsatisfactory. Herein, graphene oxide (GO), a hydrophilic material with favourable biomechanics and osteogenic capability, was added to P(MMA-AA-St) to optimize its biomechanics and bioactivity. The GO-modified self-expandable P(MMA-AA-St)-GO nanocomposite (PGBCs) exhibited outstanding compressive strength (>70 â€‹MPa), water absorption, and volume expansion, as well as a longer handling time and a reduced setting temperature. The cytocompatibility of PGBCs was superior to that of PBC, as demonstrated by CCK-8 assay, live-dead cell staining, and flow cytometry. In addition, better osteoblast attachment was observed, which could be attributed to the effects of GO. The improved level of osteogenic gene and protein expression further illustrated the improved cell-material interactions between osteoblasts and PGBCs. The results of an in vivo study performed by filling bone defects in the femoral condyles of rabbits with PGBCs demonstrated promising intraoperative handling properties and convenient implantation. Blood testing and histological staining demonstrated satisfactory in vivo biosafety. Furthermore, bone morphological and microarchitecture analyses using bone tissue staining and micro-CT scanning revealed better bone-PGBCs contact and osteogenic capability. The results of this study indicate that GO modification improved the physiochemical properties, cytocompatibility, and osteogenic capability of P(MMA-AA-St) and overcame the drawbacks of PBC, allowing its material derivatives to serve as effective implantable biomaterials.

Electrochemically Exfoliated Chlorine-Doped Graphene for Flexible All-Solid-State Micro-Supercapacitors with High Volumetric Energy Density.

Graphene-constructed micro-supercapacitors (MSCs) have received considerable attention recently, as part of the prospective wearable and portable electronics, owing to their distinctive merits of well-tunable power output, robust mechanical flexibility, and long cyclability. In the current work, the focus is on the fabrication of high-quality and solution-processible chlorine-doped graphene (Cl-G) nanosheets through a handy yet eco-friendly electrochemical exfoliation process. The Cl-G is characteristic of the large lateral size of ≈10 µm, abundant nanopores with sizes of as small as 2 nm, as well as numerous steps from the rugged surface. Arising from the rich chemical functionalities and structure defects, the all-solid-state MSC built by using Cl-G via a facile mask-assisted method delivers a large reversible capacity and ultrasteady charge/discharge performance, with the capacitance being maintained at 98.1% even after 250 000 cycles. The Cl-G-MSC with EMIMBF4 /PVDF-HFP as the electrolyte displays a large volumetric capacitance up to 160 F cm-3 at the scan rate of 5 mV s-1 and high volumetric energy density of 97.9 mW h cm-3 at the power density of 3.4 W cm-3 . The device can also output a high voltage up to 3.5 V and robust capability with 94.8% of capacitance retention upon 10 000 cycles.

De Novo Germline and Somatic Variants Convergently Promote Endothelial-to-Mesenchymal Transition in Simplex Brain Arteriovenous Malformation.

[Figure: see text].

Somatic MAP3K3 mutation defines a subclass of cerebral cavernous malformation.

Cerebral cavernous malformations (CCMs) are vascular disorders that affect up to 0.5% of the total population. About 20% of CCMs are inherited because of familial mutations in CCM genes, including CCM1/KRIT1, CCM2/MGC4607, and CCM3/PDCD10, whereas the etiology of a majority of simplex CCM-affected individuals remains unclear. Here, we report somatic mutations of MAP3K3, PIK3CA, MAP2K7, and CCM genes in CCM lesions. In particular, somatic hotspot mutations of PIK3CA are found in 11 of 38 individuals with CCMs, and a MAP3K3 somatic mutation (c.1323C>G [p.Ile441Met]) is detected in 37.0% (34 of 92) of the simplex CCM-affected individuals. Strikingly, the MAP3K3 c.1323C>G mutation presents in 95.7% (22 of 23) of the popcorn-like lesions but only 2.5% (1 of 40) of the subacute-bleeding or multifocal lesions that are predominantly attributed to mutations in the CCM1/2/3 signaling complex. Leveraging mini-bulk sequencing, we demonstrate the enrichment of MAP3K3 c.1323C>G mutation in CCM endothelium. Mechanistically, beyond the activation of CCM1/2/3-inhibited ERK5 signaling, MEKK3 p.Ile441Met (MAP3K3 encodes MEKK3) also activates ERK1/2, JNK, and p38 pathways because of mutation-induced MEKK3 kinase activity enhancement. Collectively, we identified several somatic activating mutations in CCM endothelium, and the MAP3K3 c.1323C>G mutation defines a primary CCM subtype with distinct characteristics in signaling activation and magnetic resonance imaging appearance.

Nitrogen-doped carbon encapsulated hollow ZnSe/CoSe2 nanospheres as high performance anodes for lithium-ion batteries.

Hierarchical nitrogen-doped carbon encapsulated hollow ZnSe/CoSe2 (ZnSe/CoSe2@N-C) nanospheres are fabricated by a convenient solvothermal and selenization approach, followed by a carbonization process. The as-obtained ZnSe/CoSe2@N-C possesses a multilevel nanoscale architecture composed of a thin carbon shell with a size of around 12 nm and hollow selenide nanoparticles as the core with tiny rough grains and rich voids as the subunits. The robust carbon protective shell and synergistic effect between double metal ions boost the electron and ion transportation as well as promote effective extraction and insertion of lithium ions. Hollow ZnSe/CoSe2@N-C spheres show high reversible capacity with 1153 mA h g-1 remaining over 100 cycles at 100 mA g-1. In particular, the hollow ZnSe/CoSe2@N-C spheres show an outstanding cycling stability at a high rate of 2000 mA g-1 with the reversible capacity of up to 966 mA h g-1 remaining after 500 cycles. As an advanced anode, ZnSe/CoSe2@N-C composite shows remarkable cycling stability and exceptional rate capability in the field of energy storage technologies.

Endoderm-Derived Myeloid-like Metaphocytes in Zebrafish Gill Mediate Soluble Antigen-Induced Immunity.

Immune cells in the mucosal barriers of vertebrates are highly heterogeneous in their origin and function. This heterogeneity is further exemplified by the recent discovery of ectoderm-derived immune cells-metaphocytes in zebrafish epidermis. Yet, whether non-hematopoiesis-derived immune cells generally exist in barrier tissues remains obscured. Here, we report the identification and characterization of an endoderm-derived immune cell population in the gill and intestine of zebrafish. Transcriptome analysis reveals that the endoderm-derived immune cells are myeloid-like cells with high similarities to the ectoderm-derived metaphocytes in epidermis. Like metaphocytes in epidermis, the endoderm-derived immune cells are non-phagocytic but professional in external soluble antigen uptake. Depletion of the endoderm-derived immune cells in gill hinder the local immune response to external soluble stimulants. This study demonstrates a general existence of non-hematopoiesis-derived immune cells in zebrafish mucosal barriers and challenges the prevalent view that resident immune cells in mucosal barriers arise exclusively from hematopoiesis.

Porous PtAg nanoshells/reduced graphene oxide based biosensors for low-potential detection of NADH.

A superior NADH sensing platform was constructed based on porous PtAg nanoshells supported on reduced graphene oxide (PtAg/rGO) in the absence of any enzymes and redox mediators. The PtAg/rGO composite was prepared via one-step reduction combined with galvanic replacement reaction. The as-made PtAg/rGO assembles multiple structural advantages of coherent conductive matrix, rich electroactive sites, and high specific surface area, accompanied by the unique alloying effect. The PtAg/rGO possesses adequate active reaction sites and fluent electron transport pathway towards the electrocatalytic NADH oxidation, thus presenting significantly increased oxidation current and negative shift of 330 mV in applied potential relative to the bare GCE. By virtues of the outstanding electrocatalytic activity, PtAg/rGO exhibits effective amperometric detection of NADH at 0.15 V within a wide linear concentration range of 2-2378 µM, a high sensitivity of 92.62 µA mM-1 cm-2, low detection limit of 0.2 µM, and long-term detection over 2500 s. Moreover, the as-constructed biosensors can achieve accurate NADH detection in human serum samples, indicating its promising application feasibility in fundamental and clinic research. Graphical Abstract Porous PtAg alloy nanoshells supported on reduced graphene oxide (PtAg/rGO) was prepared via a facile one-step reduction and spontaneous replacement reaction strategy. A sensitive and highly stable electrochemical biosensor based on PtAg/rGO is constructed for the quantitative detection of NADH at low applied potential.

Nanoporous platinum-copper flowers for non-enzymatic sensitive detection of hydrogen peroxide and glucose at near-neutral pH values.

Multimodal nanoporous PtCu flowers (np-PtCu) were prepared via a two-step dealloying strategy under mild conditions. The np-PtCu alloy possesses an interconnected flower-like network skeleton with multiscale pore distribution. This material was placed on a glassy carbon electrode where it shows outstanding detection performance towards hydrogen peroxide and glucose in near-neutral pH solutions. It can be attributed to the specific structure in terms of interconnected nanoscaled ligaments, rich pore openings and a synergistic alloying effect. Figures of merit for detection H2O2 assay include (a) a working voltage of 0.7 V (vs. the reversible hydrogen electrode); (b) a wide linear response range (from 0.01 to 1.7 mM), and (c) a low detection limit (0.1 µM). The respective data for the glucose assay are (a) 0.4 V, (b) 0.01-2.0 mM, and (c) 0.1 µM. The method is not interfered in the presence of common concentrations of dopamine, acetaminophen and ascorbic acid. Graphical abstract Multimodal nanoporous (np) PtCu alloy was prepared via a two-step dealloying strategy under mild conditions. Np-PtCu exhibits superior electrocatalytic activity. The assay is highly sensitive, selective, and it allows for a long-term detection of H2O2 and glucose.

An Ectoderm-Derived Myeloid-like Cell Population Functions as Antigen Transporters for Langerhans Cells in Zebrafish Epidermis.

Tissue-resident macrophages (TRMs) are highly heterogeneous and engage in a wide range of diverse functions. Yet, the heterogeneities of their origins and functions remain incompletely defined. Here, we report the identification and characterization of an ectoderm-derived myeloid-like cell, which we refer to as metaphocyte. We show that metaphocytes are highly similar to conventional Langerhans cells (cLCs), the resident macrophages in epidermis, in transcriptome, morphology, and anatomic location. However, unlike cLCs, metaphocytes respond neither to tissue injury nor to bacterial infection but rather sample soluble antigens from external environment through transepithelial protrusions and transfer them to cLCs via apoptosis-phagocytosis axis. This antigen transfer is critical for zebrafish to respond to soluble antigens because the depletion of metaphocytes significantly reduces cLC antigen uptake. Our study documents the existence of ectoderm-derived myeloid-like cells that manifest distinct function from conventional TRMs and opens a new paradigm for investigation of the heterogeneities of resident immune cells.

Hierarchical nanoporous platinum-copper alloy nanoflowers as highly active catalysts for the hydrolytic dehydrogenation of ammonia borane.

Hierarchical nanoporous platinum-copper (hnp-PtCu) alloy nanoflowers with bimodal pore/ligament size are easily fabricated by selectively dissolving Al atoms and part of Cu atoms from PtCuAl ternary alloy. The dealloyed samples consist of cross-linking porous nanoflowers with interconnected network skeleton and hollow channels penetrated. Hnp-PtCu alloy nanoflowers with different compositions exhibit dramatically enhanced catalytic activities toward the hydrolysis of ammonia borane (AB) compared with their monometallic components. The hnp-Pt35Cu65 alloy shows superior catalytic performance than the other hnp-PtCu catalysts with an initial much higher turnover frequency of 108 mol H2 min-1 (mol Pt)-1. Moreover, the hnp-Pt35Cu65 displays excellent structure stability even after the five runs for the AB hydrolysis. The as-made hnp-PtCu catalysts hold promising application potential toward the AB hydrolysis with the advantages of facile preparation, high yielding, superior catalytic activity, and high structure durability.

Nanoporous PtCo/Co3O4 composites with high catalytic activities toward hydrolytic dehydrogenation of ammonia borane.

The design and fabrication of highly active and durable catalysts for the ammonia borane (AB) hydrolysis has been one of significant issues in the application of green and economic hydrogen energy. Nanoporous (NP) PtCo/Co3O4 composites are straightforwardly fabricated by selectively etching Al atoms followed by removing Co atoms from the PtCoAl precursor alloy. By controlling the second-step dealloying, the NP-PtCo/Co3O4 composites evolved into pure nanoporous structure with Co3O4 nanosheets on the surface gradually disappeared as well different Pt/Co ratios resulted. Compared with NP-Pt and pure Co3O4 catalysts, the NP-PtCo/Co3O4 composites with different Pt/Co ratios exhibit markedly enhanced catalytic activity for the hydrolysis of AB. NP-Pt40Co60 composite with some Co3O4 nanosheets anchored on the surface shows the higher catalytic activity compared to other several samples with different Pt contents, exhibiting a high initial turnover frequency of 131mol H2 min-1 (mol Pt)-1. Meanwhile, the recyclability tests indicate that NP-Pt40Co60 composite retained 65% of the initial catalytic activity after the fifth run of hydrolysis. Therefore, the high catalytic activity and good durability render the as-made composite as a powerful catalyst candidate for the hydrolytic dehydrogenation of AB in the practical applications.

Better cold tolerance of Bt-resistant Spodoptera exigua strain and the corresponding cold-tolerant mechanism.

Spodoptera exigua is a secondary target pest of Bt cotton commercialized in China. With the continuous adoption of Bt cotton, populations of S. exigua have gradually increased. However, the cold tolerance ability of Bt-resistant S. exigua and the effect of continuous Bt diet on anti-cold materials are unknown. In our study, it was found that Bt-resistant S. exigua (Bt10) developed better with shorter larval and pupal duration and higher pupation rate compared to CK at the suboptimal low temperature. The supercooling points and freezing points of the Bt-resistant S. exigua strain were determined, and body water content and anti-cold materials such as total sugar, trehalose and glycogen, glycerol and fat were examined to explore the effect of Bt toxin on overwintering and on population increase. The results showed that the supercooling point and the freezing point of the Bt-resistant S. exigua pupae were both significantly lower than that of the Bt-susceptible strain. No difference was found in the body water content of pupae and adults between the two strains. Total sugar content of the Bt-resistant strain at both the pupal and adult stages was higher than that of the susceptible strain at the corresponding stages, and glycogen content of the Bt-resistant strain at the larval stage was higher than that of the susceptible larval S. exigua. Fat content of the Bt-resistant larvae, pupae and adults was for each higher than that of the susceptible strain, but the difference was not significant except for that of the 3rd instar larvae. Glycerol content of the Bt-resistant strain at larval, pupal and adult stages was for each higher than that of the corresponding life stages of the susceptible strain. It can be seen that more glycerol was accumulated in Bt-resistant S. exigua. The results indicate that Bt-resistant S. exigua has better cold tolerance. The contents of the anti-freeze substances of progeny, especially glycerol, were increased after previous generations were continuously fed on Bt protein, which means that the Bt-resistant secondary target pests could more easily overcome the overwinter season and become a source of crop damage the following year.

Stratified nanoporous PtTi alloys for hydrolysis of ammonia borane.

Stratified nanoporous PtTi (SNP-PtTi) alloys with bimodal size distributions and different components are successfully prepared by selectively dissolving Al atoms followed by removing part of Ti atoms from the PtTiAl precursor alloy. The as-made PtTi alloys have stratified nanoporous architecture with the first order ligaments around 50nm and the second order smaller ligaments around 6nm. The SNP-PtTi alloys with different bimetallic ratios exhibit much higher catalytic activity for the hydrolysis of ammonia borane than NP-Pt catalyst. The SNP-Pt65Ti35 alloy shows superior specific activity toward the hydrolytic dehydrogenation of ammonia borane compared with SNP-Pt50Ti50 and -Pt80Ti20, showing an initial turnover frequency of 51.4mol H2 (molPt)-1min-1. The activation energy of SNP-Pt65Ti35 was estimated to be about 39.4kJmol-1, which was small compared with most of the reported activation energy values in the literature. In addition, the recyclability tests indicate that the SNP-Pt65Ti35 retained 63% of the initial catalytic activity after the fifth run of hydrolysis. The lifetime of SNP-Pt65Ti35 was measured as 16,380 turnovers over 100h in the hydrolysis of ammonia borane before deactivation. The SNP-PtTi alloys show potential application prospect in the field of online hydrogen production due to the high catalytic performance and the facile preparation.

Nanoporous PtRu Alloys with Unique Catalytic Activity toward Hydrolytic Dehydrogenation of Ammonia Borane.

Nanoporous (NP) PtRu alloys with three different bimetallic components were straightforwardly fabricated by dealloying PtRuAl ternary alloys in hydrochloric acid. Selective etching of aluminum from source alloys generates bicontinuous network nanostructures with uniform size and structure. The as-made NP-PtRu alloys exhibit superior catalytic activity toward the hydrolytic dehydrogenation of ammonia borane (AB) than pure NP-Pt and NP-Ru owing to alloying platinum with ruthenium. The NP-Pt70 Ru30 alloy exhibits much higher specific activity toward hydrolytic dehydrogenation of AB than NP-Pt30 Ru70 and NP-Pt50 Ru50 . The hydrolysis activation energy of NP-Pt70 Ru30 was estimated to be about 38.9 kJ mol(-1) , which was lower than most of the reported activation energy values in the literature. In addition, recycling tests show that the NP-Pt70 Ru30 is still highly active in the hydrolysis of AB even after five runs, which indicates that NP-PtRu alloy accompanied by the network nanoarchitecture is beneficial to improve structural stability toward the dehydrogenation of AB.

Si/Ag composite with bimodal micro-nano porous structure as a high-performance anode for Li-ion batteries.

A one-step dealloying method is employed to conveniently fabricate a bimodal porous (BP) Si/Ag composite in high throughput under mild conditions. Upon dealloying the carefully designed SiAgAl ternary alloy in HCl solution at room temperature, the obtained Si/Ag composite has a uniform bicontinuous porous structure in three dimensions with micro-nano bimodal pore size distribution. Compared with the traditional preparation methods for porous Si and Si-based composites, this dealloying route is easily operated and environmentally benign. More importantly, it is convenient to realize the controllable components and uniform distribution of Si and Ag in the product. Owing to the rich porosity of the unique BP structure and the incorporation of highly conductive Ag, the as-made Si/Ag composite possesses the improved conductivity and alleviated volume changes of the Si network during repeated charging and discharging. As expected, the BP Si/Ag anode exhibits high capacity, excellent cycling reversibility, long cycling life and good rate capability for lithium storage. When the current rate is up to 1 A g(-1), BP Si/Ag can deliver a stable reversible capacity above 1000 mA h g(-1), and exhibits a capacity retention of up to 89.2% against the highest capacity after 200 cycles. With the advantages of unique performance and easy preparation, the BP Si/Ag composite holds great application potential as an advanced anode material for Li-ion batteries.