Multimodal cell atlas of the ageing human skeletal muscle.

Muscle atrophy and functional decline (sarcopenia) are common manifestations of frailty and are critical contributors to morbidity and mortality in older people1. Deciphering the molecular mechanisms underlying sarcopenia has major implications for understanding human ageing2. Yet, progress has been slow, partly due to the difficulties of characterizing skeletal muscle niche heterogeneity (whereby myofibres are the most abundant) and obtaining well-characterized human samples3,4. Here we generate a single-cell/single-nucleus transcriptomic and chromatin accessibility map of human limb skeletal muscles encompassing over 387,000 cells/nuclei from individuals aged 15 to 99 years with distinct fitness and frailty levels. We describe how cell populations change during ageing, including the emergence of new populations in older people, and the cell-specific and multicellular network features (at the transcriptomic and epigenetic levels) associated with these changes. On the basis of cross-comparison with genetic data, we also identify key elements of chromatin architecture that mark susceptibility to sarcopenia. Our study provides a basis for identifying targets in the skeletal muscle that are amenable to medical, pharmacological and lifestyle interventions in late life.

Senescence atlas reveals an aged-like inflamed niche that blunts muscle regeneration.

Tissue regeneration requires coordination between resident stem cells and local niche cells1,2. Here we identify that senescent cells are integral components of the skeletal muscle regenerative niche that repress regeneration at all stages of life. The technical limitation of senescent-cell scarcity3 was overcome by combining single-cell transcriptomics and a senescent-cell enrichment sorting protocol. We identified and isolated different senescent cell types from damaged muscles of young and old mice. Deeper transcriptome, chromatin and pathway analyses revealed conservation of cell identity traits as well as two universal senescence hallmarks (inflammation and fibrosis) across cell type, regeneration time and ageing. Senescent cells create an aged-like inflamed niche that mirrors inflammation associated with ageing (inflammageing4) and arrests stem cell proliferation and regeneration. Reducing the burden of senescent cells, or reducing their inflammatory secretome through CD36 neutralization, accelerates regeneration in young and old mice. By contrast, transplantation of senescent cells delays regeneration. Our results provide a technique for isolating in vivo senescent cells, define a senescence blueprint for muscle, and uncover unproductive functional interactions between senescent cells and stem cells in regenerative niches that can be overcome. As senescent cells also accumulate in human muscles, our findings open potential paths for improving muscle repair throughout life.

Rolling back human pluripotent stem cells to an eight-cell embryo-like stage.

After fertilization, the quiescent zygote experiences a burst of genome activation that initiates a short-lived totipotent state. Understanding the process of totipotency in human cells would have broad applications. However, in contrast to in mice1,2, demonstration of the time of zygotic genome activation or the eight-cell (8C) stage in in vitro cultured human cells has not yet been reported, and the study of embryos is limited by ethical and practical considerations. Here we describe a transgene-free, rapid and controllable method for producing 8C-like cells (8CLCs) from human pluripotent stem cells. Single-cell analysis identified key molecular events and gene networks associated with this conversion. Loss-of-function experiments identified fundamental roles for DPPA3, a master regulator of DNA methylation in oocytes3, and TPRX1, a eutherian totipotent cell homeobox (ETCHbox) family transcription factor that is absent in mice4. DPPA3 induces DNA demethylation throughout the 8CLC conversion process, whereas TPRX1 is a key executor of 8CLC gene networks. We further demonstrate that 8CLCs can produce embryonic and extraembryonic lineages in vitro or in vivo in the form of blastoids5 and complex teratomas. Our approach provides a resource to uncover the molecular process of early human embryogenesis.

Cell transcriptomic atlas of the non-human primate Macaca fascicularis.

Studying tissue composition and function in non-human primates (NHPs) is crucial to understand the nature of our own species. Here we present a large-scale cell transcriptomic atlas that encompasses over 1 million cells from 45 tissues of the adult NHP Macaca fascicularis. This dataset provides a vast annotated resource to study a species phylogenetically close to humans. To demonstrate the utility of the atlas, we have reconstructed the cell-cell interaction networks that drive Wnt signalling across the body, mapped the distribution of receptors and co-receptors for viruses causing human infectious diseases, and intersected our data with human genetic disease orthologues to establish potential clinical associations. Our M. fascicularis cell atlas constitutes an essential reference for future studies in humans and NHPs.

Neurotrophin-3 from the dentate gyrus supports postsynaptic sites of mossy fiber-CA3 synapses and hippocampus-dependent cognitive functions.

At the center of the hippocampal tri-synaptic loop are synapses formed between mossy fiber (MF) terminals from granule cells in the dentate gyrus (DG) and proximal dendrites of CA3 pyramidal neurons. However, the molecular mechanism regulating the development and function of these synapses is poorly understood. In this study, we showed that neurotrophin-3 (NT3) was expressed in nearly all mature granule cells but not CA3 cells. We selectively deleted the NT3-encoding Ntf3 gene in the DG during the first two postnatal weeks to generate a Ntf3 conditional knockout (Ntf3-cKO). Ntf3-cKO mice of both sexes had normal hippocampal cytoarchitecture but displayed impairments in contextual memory, spatial reference memory, and nest building. Furthermore, male Ntf3-cKO mice exhibited anxiety-like behaviors, whereas female Ntf3-cKO showed some mild depressive symptoms. As MF-CA3 synapses are essential for encoding of contextual memory, we examined synaptic transmission at these synapses using ex vivo electrophysiological recordings. We found that Ntf3-cKO mice had impaired basal synaptic transmission due to deficits in excitatory postsynaptic currents mediated by AMPA receptors but normal presynaptic function and intrinsic excitability of CA3 pyramidal neurons. Consistent with this selective postsynaptic deficit, Ntf3-cKO mice had fewer and smaller thorny excrescences on proximal apical dendrites of CA3 neurons and lower GluR1 levels in the stratum lucidum area where MF-CA3 synapses reside but normal MF terminals, compared with control mice. Thus, our study indicates that NT3 expressed in the dentate gyrus is crucial for the postsynaptic structure and function of MF-CA3 synapses and hippocampal-dependent memory.

Discrete TrkB-expressing neurons of the dorsomedial hypothalamus regulate feeding and thermogenesis.

Mutations in the TrkB neurotrophin receptor lead to profound obesity in humans, and expression of TrkB in the dorsomedial hypothalamus (DMH) is critical for maintaining energy homeostasis. However, the functional implications of TrkB-fexpressing neurons in the DMH (DMHTrkB) on energy expenditure are unclear. Additionally, the neurocircuitry underlying the effect of DMHTrkB neurons on energy homeostasis has not been explored. In this study, we show that activation of DMHTrkB neurons leads to a robust increase in adaptive thermogenesis and energy expenditure without altering heart rate or blood pressure, while silencing DMHTrkB neurons impairs thermogenesis. Furthermore, we reveal neuroanatomically and functionally distinct populations of DMHTrkB neurons that regulate food intake or thermogenesis. Activation of DMHTrkB neurons projecting to the raphe pallidus (RPa) stimulates thermogenesis and increased energy expenditure, whereas DMHTrkB neurons that send collaterals to the paraventricular hypothalamus (PVH) and preoptic area (POA) inhibit feeding. Together, our findings provide evidence that DMHTrkB neuronal activity plays an important role in regulating energy expenditure and delineate distinct neurocircuits that underly the separate effects of DMHTrkB neuronal activity on food intake and thermogenesis.

Fast Interfacial Carrier Dynamics Modulated by Bidirectional Charge Transport Channels in ZnIn2 S4 -based Composite Photoanodes Probed by Scanning Photoelectrochemical Microscopy.

Limited charge separation/transport efficiency remains the primary obstacle of achieving satisfying photoelectrochemical (PEC) water splitting performance. Therefore, it is essential to develop diverse interfacial engineering strategies to mitigate charge recombination. Despite obvious progress having been made, most works only considered a single-side modulation in either the electrons of conduction band or the holes of valence band in a semiconductor photoanode, leading to a limited PEC performance enhancement. Beyond this conventional thinking, we developed a novel coupling modification strategy to achieve a composite electrode with bidirectional carrier transport for a better charge separation, in which Ti2 C3 Tx MXene quantum dots (MQDs) and α-Fe2 O3 nanodots (FO) are anchored on the surface of ZnIn2 S4 (ZIS) nanoplates, resulting in markedly improved PEC water splitting of pure ZIS photoanode. Systematic studies indicated that the bidirectional charge transfer pathways were stimulated due to MQDs as "electron extractor" and S-O bonds as carriers transport channels, which synergistically favors significantly enhanced charge separation. The enhanced kinetic behavior at the FO/MQDs/ZIS interfaces was systematically and quantitatively evaluated by a series of methods, especially scanning photoelectrochemical microscopy. This work may deepen our understanding of interfacial charge separation, and provide valuable guidance for the rational design and fabrication of high-performance composite electrodes.

Synthesis of Crystalline Phosphine-Graphdiyne with Self-Adaptive p-π Conjugation.

"Dynamic" behavior materials with high surface activity and the ability of chemical bond conversion are the frontier materials in the field of renewable energy. The outstanding feature of these materials is that they have adaptive electronic properties that external stimuli can adjust. An original discovery in a new crystalline two-dimensional phosphine-graphdiyne (P-GDY) material is described here. Although the p-π conjugation of most trivalent phosphorus π-systems is insignificant because of the pyramidal configuration, the lone pair electrons of phosphorus atoms participate strongly in the delocalization under the influence of the interlayer van der Waals forces in P-GDY. Due to the dynamically reversible nature of noncovalent interactions (p-π conjugation), P-GDY exhibits a specific adaptive behavior and realizes the responsive reversible transport of a lithium ion by regulating p-π interactions. Our findings would provide the potential to develop a new family of responsive materials with tunable structures.

Adaptive laboratory evolution of Rhodococcus rhodochrous DSM6263 for chlorophenol degradation under hypersaline condition.

BACKGROUND: Normally, a salt amount greater than 3.5% (w/v) is defined as hypersaline. Large amounts of hypersaline wastewater containing organic pollutants need to be treated before it can be discharged into the environment. The most critical aspect of the biological treatment of saline wastewater is the inhibitory/toxic effect exerted on bacterial metabolism by high salt concentrations. Although efforts have been dedicated to improving the performance through the use of salt-tolerant or halophilic bacteria, the diversities of the strains and the range of substrate spectrum remain limited, especially in chlorophenol wastewater treatment. RESULTS: In this study, a salt-tolerant chlorophenol-degrading strain was generated from Rhodococcus rhodochrous DSM6263, an original aniline degrader, by adaptive laboratory evolution. The evolved strain R. rhodochrous CP-8 could tolerant 8% NaCl with 4-chlorophenol degradation capacity. The synonymous mutation in phosphodiesterase of strain CP-8 may retard the hydrolysis of cyclic adenosine monophosphate (cAMP), which is a key factor reported in the osmoregulation. The experimentally verified up-regulation of intracellular cAMP level in the evolved strain CP-8 contributes to the improvement of growth phenotype under high osmotic condition. Additionally, a point mutant of the catechol 1,2-dioxygenase, CatAN211S, was revealed to show the 1.9-fold increment on activity, which the mechanism was well explained by molecular docking analysis. CONCLUSIONS: This study developed one chlorophenol-degrading strain with extraordinary capacity of salt tolerance, which showed great application potential in hypersaline chlorophenol wastewater treatment. The synonymous mutation in phosphodiesterase resulted in the change of intracellular cAMP concentration and then increase the osmotic tolerance in the evolved strain. The catechol 1,2-dioxygenase mutant with improved activity also facilitated chlorophenol removal since it is the key enzyme in the degradation pathway.

Distinct role of long 3' UTR BDNF mRNA in spine morphology and synaptic plasticity in hippocampal neurons.

The brain produces two brain-derived neurotrophic factor (BDNF) transcripts, with either short or long 3' untranslated regions (3' UTRs). The physiological significance of the two forms of mRNAs encoding the same protein is unknown. Here, we show that the short and long 3' UTR BDNF mRNAs are involved in different cellular functions. The short 3' UTR mRNAs are restricted to somata, whereas the long 3' UTR mRNAs are also localized in dendrites. In a mouse mutant where the long 3' UTR is truncated, dendritic targeting of BDNF mRNAs is impaired. There is little BDNF in hippocampal dendrites despite normal levels of total BDNF protein. This mutant exhibits deficits in pruning and enlargement of dendritic spines, as well as selective impairment in long-term potentiation in dendrites, but not somata, of hippocampal neurons. These results provide insights into local and dendritic actions of BDNF and reveal a mechanism for differential regulation of subcellular functions of proteins.

Gradient Graphdiyne Induced Copper and Oxygen Vacancies in Cu0.95 V2 O5 Anodes for Fast-Charging Lithium-Ion Batteries.

Vacancies can significantly affect the performance of metal oxide materials. Here, a gradient graphdiyne (GDY) induced Cu/O-dual-vacancies abundant Cu0.95 V2 O5 @GDY heterostructure material has been prepared as a competitive fast-charging anode material. Cu0.95 V2 O5 self-catalyzes the growth of gradient GDY with rich alkyne-alkene complex in the inner layer and rich alkyne bonds in the outer layer, leading to the formation of Cu and O vacancies in Cu0.95 V2 O5 . The synergistic effect of vacancies and gradient GDY results in the electron redistribution at the hetero-interface to drive the generation of a built-in electric field. Thus, the Li-ion transport kinetics, electrochemical reaction reversibility and Li storage sites of Cu0.95 V2 O5 are greatly enhanced. The Cu0.95 V2 O5 @GDY anodes show excellent fast-charging performance with high capacities and negligible capacity decay for 10 000 cycles and 20 000 cycles at extremely high current densities of 5 A g-1 and 10 A g-1 , respectively. Over 30 % of capacity can be delivered in 35 seconds.

TrkB-expressing neurons in the dorsomedial hypothalamus are necessary and sufficient to suppress homeostatic feeding.

Genetic evidence indicates that brain-derived neurotrophic factor (BDNF) signaling through the TrkB receptor plays a critical role in the control of energy balance. Mutations in the BDNF or the TrkB-encoding NTRK2 gene have been found to cause severe obesity in humans and mice. However, it remains unknown which brain neurons express TrkB to control body weight. Here, we report that TrkB-expressing neurons in the dorsomedial hypothalamus (DMH) regulate food intake. We found that the DMH contains both glutamatergic and GABAergic TrkB-expressing neurons, some of which also express the leptin receptor (LepR). As revealed by Fos immunohistochemistry, a significant number of TrkB-expressing DMH (DMHTrkB) neurons were activated upon either overnight fasting or after refeeding. Chemogenetic activation of DMHTrkB neurons strongly suppressed feeding in the dark cycle when mice are physiologically hungry, whereas chemogenetic inhibition of DMHTrkB neurons greatly promoted feeding in the light cycle when mice are physiologically satiated, without affecting feeding in the dark cycle. Neuronal tracing revealed that DMHTrkB neurons do not innervate neurons expressing agouti-related protein in the arcuate nucleus, indicating that DMHTrkB neurons are distinct from previously identified LepR-expressing GABAergic DMH neurons that suppress feeding. Furthermore, selective Ntrk2 deletion in the DMH of adult mice led to hyperphagia, reduced energy expenditure, and obesity. Thus, our data show that DMHTrkB neurons are a population of neurons that are necessary and sufficient to suppress appetite and maintain physiological satiation. Pharmacological activation of these neurons could be a therapeutic intervention for the treatment of obesity.

Relationship between the coprecipitation of phosphorus-on-calcite by submerged macrophytes and the phosphorus cycle in water.

To assess potential phosphorus removal, we utilized Potamogeton crispus to determine the effects of calcium addition on phosphorus removal. Plastic film was used to block material exchange between the overlying water and the sediment, and we compared the experimental results with long-term monitoring results of Yimeng Lake, which contained a dense population of P. crispus. The results revealed that the first 10-40 days constituted a period of rapid P decrease, as P. crispus could effectively remove the phosphorus in the water through coprecipitation of CaCO3-P. The treatment groups indicated that P. crispus released calcium into the overlying water, and after the addition of calcium ions, P. crispus showed increased phosphorus removal efficiency in the water. Total phosphorus (TP) and P/Ca content increased with increasing pH in the treatment groups, and the TP and pH declined as the calcium content increased in the treatment groups. Long-term field observations showed that the calcium-to-phosphorus ratio in the coprecipitates was dependent on the pH during the crystallization process. Thus, water calcium driven by P. crispus plays an important role in the phosphorus cycle of water, due to P. crispus assisted precipitation. This study revealed the effect of P. crispus on the water purification, the migration and transformation of Ca and P in sediment and overlying water under the condition of sediment calcium addition, so as to provide a theoretical basis for the ecological restoration of shallow lakes eutrophication.

Self-Expanding Ion-Transport Channels on Anodes for Fast-Charging Lithium-Ion Batteries.

We propose self-expanding lithium-ion transport channels to construct a fast-charging anode and realize high-performance fast-charging Li-ion batteries. The self-expanded Li-ion transport channels can be enabled by a self-reversible conversion of chemical bonds with different bond lengths in the anode driven by the interactions with Li ions during cycling, reduce the energy barrier of Li-ion transport and allow a fast Li-ion solid-state diffusion, whereby the severe voltage polarization and Li metal plating are effectively eliminated. Our proof-of-concept demonstration of the self-reversible conversion of chemical bonds on the surface of graphdiyne successfully verifies the self-expanded Li-ion transport channels, self-accelerated Li in-plane/out-of-plane migration, and superior fast-charging capability with a high capacity (342 mA h g-1 ) and an ultra-long lifespan (22 000 cycles) under extremely fast-charging conditions (6 C rate, 1 C=744 mA g-1 ), even at low temperatures (-10 °C).

A simple and efficient sample preparation for taxanes in Taxus chinensis needles with natural menthol-based aqueous deep eutectic solvent.

Taxanes are natural anticancer constituents, and the sample preparation from matrix normally depends on organochlorine solvents. In this study, green and natural menthol-based aqueous deep eutectic solvent was synthesized and used for sample preparation for taxanes. Five key parameters were optimized and the optimal preparation conditions were as follows: menthol/1-propanol ratio 1:1 (mol/mol), solid-liquid ratio 1:30 g/mL, extraction time 30 min, ultrasonic power 250 W, and water content 80%. Under the above conditions, the total extraction efficiency of seven main taxanes was 1.25- to 1.44-fold to the conventional methods. In addition, a high-performance liquid chromatography method with C18 column was established for quantitation of seven main taxanes in <25 min, which had excellent linearity (R2  > 0.9986), precision (relative standard deviation < 3.00%), repeatability (relative standard deviation < 3.69%), and recovery (90.26-109.00%). This method performed the extraction, and enrichment processes simultaneously, and it had advantages such as high extraction efficiency, simple operation, low cost, and eco-friendliness. This work indicated that the natural menthol-based deep eutectic solvent aqueous could be an excellent alternative to the sample preparation from Taxus or other plants.

Discovery of SCY45, a Natural Small-Molecule MDM2-p53 Interaction Inhibitor.

The disruption of the MDM2-p53 interaction has been regarded as an attractive strategy for anticancer drug discovery. Here, the natural small-molecule SCY45 was identified as a potent MDM2-p53 interaction inhibitor based on fluorescence polarization and molecular modeling. SCY45 inhibited the MDM2-p53 interaction with an IC50 value of 4.93±0.08 µm. The structural modeling results showed that SCY45 not only had high structural similarity with nutlin-3a, a well-reported MDM2-P53 interaction inhibitor, but also bound to the p53 binding pocket of MDM2 with a binding mode similar to that of nutlin-3a. Moreover, SCY45 reduced the cell viability in cancer cells with MDM2 gene amplification. SCY45 showed the highest inhibition for SJSA-1 cells, which exhibit excessive MDM2 gene amplification, with an IC50 value of 7.54±0.29 µm, whereas SCY45 showed a weaker inhibition for 22Rv1 cells and A549 cells, which have a single copy of the MDM2 gene, with IC50 values of 18.47±0.75 µm and 31.62±1.96 µm, respectively.

Constitutive expression of Bcl-2 induces epithelial-Mesenchymal transition in mammary epithelial cells.

BACKGROUND: Bcl-2 (B cell lymphoma/leukemia gene-2) is the first proto-oncogene recognized to function by inhibiting programmed cell death/apoptosis. Although much is known about the anti-apoptotic ability of Bcl-2, little information is available concerning its function in other cellular processes, such as cell differentiation. METHODS: In this study, stable cell lines from pre-malignant MCF10ATG3B mammary epithelial cells, a cell line derived from a human proliferative breast disease model, to express exogenous Bcl-2 was established. CMV promoter driven Bcl-2 expression vector or empty vector was transfected into MCF10ATG3B human mammary epithelial cells to investigate the effects of Bcl-2 on mammary epithelial cells. In addition, western blot and immunofluoresence staining were employed to testify the marker proteins of both mesenchymal and epithelial cells. RESULTS: Unexpectedly, a dramatic change of phenotype from epithelial cells to fibroblast-like cells was observed in Bcl-2-transfected cells. Western blot analysis and immunofluoresence staining results demonstrated that the E-cadherin and desmoplakin, markers of epithelial cells, were downregulated in the Bcl-2-transfected cells. However, N-cadherin and vimentin, markers of mesenchymal cells, were upregulated in these cells. Redistributions of cytokeratin and beta-catenin were also observed in the Bcl-2-transfected cells. Our results further showed that the Bcl-2-transfected MCF10ATG3B cells retained some epithelial markers, such as epithelial specific antigen (ESA) and epithelial membrane antigen (EMA), indicating their epithelial origin. In addition, cell migration and invasion was substantially increased in Bcl-2 transfected cells. CONCLUSION: Taken together, our results strongly indicate that in addition to its anti-apoptotic function, Bcl-2 is also involved in the epithelial-mesenchymal transition (EMT), a fundamental mechanism in normal morphogenesis and pathogenesis of some diseases.

Kinetics of pulmonary immune cells, antibody responses and their correlations with the viral clearance of influenza A fatal infection in mice.

Fatal influenza A virus infection is a major threat to public health throughout the world. Lung macrophages and neutrophils have critical roles for both the pathogenesis and viral clearance of fatal viral infections. These are complicated by the interaction of innate immunity and adaptive immunity against viral infection. In this study, we investigated the overall kinetics of lung macrophages, neutrophils, CD4⁺T cells, CD8⁺T cells, CD38⁺ cells, and CD138⁺ cells, the levels of antibody and cytokine responses, both in the early and late phases of fatal infection with A/PR/8/34 (H1N1) virus in mice. The changes in lung viral load were also evaluated. We found that pulmonary macrophages and neutrophils both accumulated in the early and late phases of fatal infections and they positively correlated with the lung and serum antibody titers, and negatively correlated with the viral load locally. The secretion of IL-6 might relate to high numbers of macrophages and neutrophils in the early infection. The work implies that pulmonary macrophages, neutrophils and the antibody response all have an essential role in virus elimination of fatal influenza A viral infection. These findings may have implications for the development of prophylactic and therapeutic strategies in fatal influenza A viral infection. Further evaluation of the cooperation among macrophages, neutrophils and antibody responses in eliminating the virus with fatal infection is needed.

The over-expression of Chrysanthemum crassum CcSOS1 improves the salinity tolerance of chrysanthemum.

Soil salinity represents a major constraint on plant growth. Here, we report that the over-expression of the Chrysanthemum crassum plasma membrane Na(+)/H(+) antiporter gene CcSOS1, driven by the CaMV 35S promoter, improved the salinity tolerance of chrysanthemum 'Jinba'. In salinity-stressed transgenic plants, both the proportion of the leaf area suffering damage and the electrical conductivity of the leaf were lower in the transgenic lines than in salinity-stressed wild type plants. After a 6 day exposure to 200 mM NaCl, the leaf content of both chlorophyll (a+b) and proline was higher in the transgenic than in the wild type plants. The activity of both superoxide dismutase and peroxidase was higher in the transgenic than in the wild type plants throughout the period of NaCl stress. The transgenic plants had a stronger control over the ingress of Na(+) into the plant, particularly with respect to the youngest leaves, and so maintained a more favorable K(+)/Na(+) ratio. The result suggests that a possible strategy for improving the salinity tolerance of chrysanthemum could target the restriction of Na(+) accumulation. This study is the first to report the transgenic expression of a Na(+) efflux carrier in chrysanthemum.