Activity

  • Buckley Knapp posted an update 2 weeks, 4 days ago

    During the Cretaceous, the Indian plate moved towards Eurasia at the fastest rates ever recorded. The details of this journey are preserved in the Indian Ocean seafloor, which document two distinct pulses of fast motion, separated by a noticeable slowdown. The nature of this rapid acceleration, followed by a rapid slowdown and then succeeded by a second speedup, is puzzling to explain. Using an extensive observation dataset and numerical models of subduction, we show that the arrival of the Reunion mantle plume started a sequence of events that can explain this history of plate motion. The forces applied by the plume initiate an intra-oceanic subduction zone, which eventually adds enough additional force to drive the plates at the anomalously fast speeds. The two-stage closure of a double subduction system, including accretion of an island arc at 50 million years ago, may help reconcile geological evidence for a protracted India-Eurasia collision.Development of new approaches to biomimetically reconstruct vasculature networks remains challenging in regenerative medicine. We introduce a particle-based artificial stem cell spheroid (ASSP) technology that recapitulates paracrine functions of three-dimensional (3D) SSPs for vasculature regeneration. Specifically, we used a facile method to induce the aggregation of stem cells into 3D spheroids, which benefited from hypoxia microenvironment-driven and enhanced secretion of proangiogenic bioactive factors. Furthermore, we artificially reconstructed 3D spheroids (i.e., ASSP) by integration of SSP-secreted factors into micro-/nanoparticles with cell membrane-derived surface coatings. The easily controllable sizes of the ASSP particles provided superior revascularization effects on the ischemic tissues in hindlimb ischemia models through local administration of ASSP microparticles and in myocardial infarction models via the systemic delivery of ASSP nanoparticles. The strategy offers a promising therapeutic option for ischemic tissue regeneration and addresses issues faced by the bottlenecked development in the delivery of stem cell therapies.Superstructured colloidal materials exploit the synergies between components to develop new or enhanced functions. Cohesion is a primary requirement for scaling up these assemblies into bulk materials, and it has only been fulfilled in case-specific bases. Here, we demonstrate that the topology of nanonetworks formed from cellulose nanofibrils (CNFs) enables robust superstructuring with virtually any particle. An intermixed network of fibrils with particles increases the toughness of the assemblies by up to three orders of magnitude compared, for instance, to sintering. Supramolecular cohesion is transferred from the fibrils to the constructs following a power law, with a constant decay factor for particle sizes from 230 nm to 40 μm. Our findings are applicable to other nanofiber dimensions via a rationalization of the morphological aspects of both particles and nanofibers. CNF-based cohesion will move developments of functional colloids from laboratory-scale toward their implementation in large-scale nanomanufacturing of bulk materials.Soft machines typically exhibit slow locomotion speed and low manipulation strength because of intrinsic limitations of soft materials. Here, we present a generic design principle that harnesses mechanical instability for a variety of spine-inspired fast and strong soft machines. Unlike most current soft robots that are designed as inherently and unimodally stable, our design leverages tunable snap-through bistability to fully explore the ability of soft robots to rapidly store and release energy within tens of milliseconds. We demonstrate this generic design principle with three high-performance soft machines High-speed cheetah-like galloping crawlers with locomotion speeds of 2.68 body length/s, high-speed underwater swimmers (0.78 body length/s), and tunable low-to-high-force soft grippers with over 1 to 103 stiffness modulation (maximum load capacity is 11.4 kg). Our study establishes a new generic design paradigm of next-generation high-performance soft robots that are applicable for multifunctionality, different actuation methods, and materials at multiscales.The historical course of evolutionary diversification shapes the current distribution of biodiversity, but the main forces constraining diversification are still a subject of debate. We unveil the evolutionary structure of tree species assemblages across the Americas to assess whether an inability to move or an inability to evolve is the predominant constraint in plant diversification and biogeography. We find a fundamental divide in tree lineage composition between tropical and extratropical environments, defined by the absence versus presence of freezing temperatures. Within the Neotropics, we uncover a further evolutionary split between moist and dry forests. selleck kinase inhibitor Our results demonstrate that American tree lineages tend to retain their ancestral environmental relationships and that phylogenetic niche conservatism is the primary force structuring the distribution of tree biodiversity. Our study establishes the pervasive importance of niche conservatism to community assembly even at intercontinental scales.Using broad-spectrum antibiotics for microbial infection may cause flora disequilibrium, drug-resistance, etc., seriously threatening human health. Here, we design a human defensin-6 mimic peptide (HDMP) that inhibits bacterial invasion in vivo through mimicking the mechanisms of human defensin-6 with high efficiency and precision. The HDMP with ligand and self-assembling peptide sequence recognizes bacteria through ligand-receptor interactions and subsequently traps bacteria by an in situ adaptive self-assembly process and resulting nanofibrous networks; these trapped bacteria are unable to invade host cells. In four animal infection models, the infection rate was markedly decreased. Notably, administration of HDMP (5 mg/kg) nanoparticles increased the survival rate of mice with methicillin-resistant S. aureus bacteremia by as much as 100%, even more than that of vancomycin treatment (5 mg/kg, 83.3%)-treated group, the golden standard of antibiotics. This biomimetic peptide shows great potential as a precise and highly efficient antimicrobial agent.Optical microscopy, owing to its noninvasiveness and subcellular resolution, enables in vivo visualization of neuronal structure and function in the physiological context. Optical-sectioning structured illumination microscopy (OS-SIM) is a widefield fluorescence imaging technique that uses structured illumination patterns to encode in-focus structures and optically sections 3D samples. However, its application to in vivo imaging has been limited. In this study, we optimized OS-SIM for in vivo neural imaging. We modified OS-SIM reconstruction algorithms to improve signal-to-noise ratio and correct motion-induced artifacts in live samples. Incorporating an adaptive optics (AO) module to OS-SIM, we found that correcting sample-induced optical aberrations was essential for achieving accurate structural and functional characterizations in vivo. With AO OS-SIM, we demonstrated fast, high-resolution in vivo imaging with optical sectioning for structural imaging of mouse cortical neurons and zebrafish larval motor neurons, and functional imaging of quantal synaptic transmission at Drosophila larval neuromuscular junctions.Soil organic carbon (SOC) stored in permafrost across the high-latitude/altitude Northern Hemisphere represents an important potential carbon source under future warming. Here, we provide a comprehensive investigation on the spatiotemporal dynamics of SOC over the high-altitude Tibetan Plateau (TP), which has received less attention compared with the circum-Arctic region. The permafrost region covers ~42% of the entire TP and contains ~37.21 Pg perennially frozen SOC at the baseline period (2006-2015). With continuous warming, the active layer is projected to further deepen, resulting in ~1.86 ± 0.49 Pg and ~3.80 ± 0.76 Pg permafrost carbon thawing by 2100 under moderate and high representative concentration pathways (RCP4.5 and RCP8.5), respectively. This could largely offset the regional carbon sink and even potentially turn the region into a net carbon source. Our findings also highlight the importance of deep permafrost thawing that is generally ignored in current Earth system models.Coxsackievirus B (CVB) enteroviruses are common human pathogens known to cause severe diseases including myocarditis, chronic dilated cardiomyopathy, and aseptic meningitis. CVBs are also hypothesized to be a causal factor in type 1 diabetes. Vaccines against CVBs are not currently available, and here we describe the generation and preclinical testing of a novel hexavalent vaccine targeting the six known CVB serotypes. We show that the vaccine has an excellent safety profile in murine models and nonhuman primates and that it induces strong neutralizing antibody responses to the six serotypes in both species without an adjuvant. We also demonstrate that the vaccine provides immunity against acute CVB infections in mice, including CVB infections known to cause virus-induced myocarditis. In addition, it blocks CVB-induced diabetes in a genetically permissive mouse model. Our preclinical proof-of-concept studies demonstrate the successful generation of a promising hexavalent CVB vaccine with high immunogenicity capable of preventing CVB-induced diseases.Sleep is plastic and is influenced by ecological factors and environmental changes. The mechanisms underlying sleep plasticity are not well understood. We show that manipulations that impair flight in Drosophila increase sleep as a form of sleep plasticity. We disrupted flight by blocking the wing-expansion program, genetically disrupting flight, and by mechanical wing perturbations. We defined a new sleep regulatory circuit starting with specific wing sensory neurons, their target projection neurons in the ventral nerve cord, and the neurons they connect to in the central brain. In addition, we identified a critical neuropeptide (burs) and its receptor (rickets) that link wing expansion and sleep. Disrupting flight activates these sleep-promoting projection neurons, as indicated by increased cytosolic calcium levels, and stably increases the number of synapses in their axonal projections. These data reveal an unexpected role for flight in regulating sleep and provide new insight into how sensory processing controls sleep need.The prototypical genetic autoimmune disease is immune dysregulation polyendocrinopathy enteropathy X-linked (IPEX) syndrome, a severe pediatric disease with limited treatment options. IPEX syndrome is caused by mutations in the forkhead box protein 3 (FOXP3) gene, which plays a critical role in immune regulation. As a monogenic disease, IPEX is an ideal candidate for a therapeutic approach in which autologous hematopoietic stem and progenitor (HSPC) cells or T cells are gene edited ex vivo and reinfused. Here, we describe a CRISPR-based gene correction permitting regulated expression of FOXP3 protein. We demonstrate that gene editing preserves HSPC differentiation potential, and that edited regulatory and effector T cells maintain their in vitro phenotype and function. Additionally, we show that this strategy is suitable for IPEX patient cells with diverse mutations. These results demonstrate the feasibility of gene correction, which will be instrumental for the development of therapeutic approaches for other genetic autoimmune diseases.