Biology subjects

Hu, Y.

Publications and source records attributed to Hu, Y..

At least 235 records · Page 13Linked to original sources

bioRxiv2024

Telomere-to-telomere African wild rice (Oryza longistaminata) reference genome reveals segmental and structural variation

Rice (Oryza sativa) is one of the most important staple food crops worldwide, and its wild relatives serve as an important gene pool in its breeding. Compared with cultivated rice species, African wild rice (Oryza longistaminata) has several advantageous traits, such as resistance to increased biomass production, clonal propagation via rhizomes, and biotic stresses. However, previous O. longistaminata genome assemblies have been hampered by gaps and incompleteness, restricting detailed investigations into their genomes. To streamline breeding endeavors and facilitate functional genomics studies, we generated a 343-Mb telomere-to-telomere (T2T) genome assembly for this species, covering all telomeres and centromeres across the 12 chromosomes. This newly assembled genome has markedly improved over previous versions. Comparative analysis revealed a high degree of synteny with previously published genomes. A large number of structural variations were identified between the O. longistaminata and O. sativa. A total of 2,466 segmentally duplicated genes were identified and enriched in cellular amino acid metabolic processes. We detected a slight expansion of some subfamilies of resistance genes and transcription factors. This newly assembled T2T genome of O. longistaminata provides a valuable resource for the exploration and exploitation of beneficial alleles present in wild relative species of cultivated rice.

genomics↗

bioRxiv2024

Comprehensive Database of Circular Permutations: Systematic Detection and Analysis Using Deep Learning

This study developed a robust method to detect circular permutations in the Protein Data Bank, analyzing 287,081 proteins with sequence lengths under 800 residues. By employing Foldseek and MMseqs2 for similarity searches and refining results with TM-align, icarus, and plmCP, we identified 20,801 potential circular permutation pairs and 3,351 unique circular permutation proteins. These findings have been compiled into PermuStructDB, a comprehensive database dedicated to circular permutation proteins. This approach, along with the establishment of PermuStructDB, significantly advances our understanding of protein structural variations and evolutionary adaptations, providing a valuable resource for future research in protein engineering and design.

bioinformatics↗

bioRxiv2024

Placental and fetal microbiota in rhesus macaque: a case study using metagenomic sequencing

Recent evidence challenging the notion of a sterile intrauterine environment has sparked research into the origins and effects of fetal microbiota on immunity development during gestation. Rhesus macaques (RMs) serve as valuable non-human primate (NHP) models due to their similarities to humans in development, placental structure, and immune response. In this study, metagenomic analysis was applied to the placenta, umbilical cord, spleen, gastrointestinal (GI) tissues of an unborn RM fetus, and the maternal intestine, revealing the diversity and functionality of microbes in these tissues. We observed substantial microbial sharing between the mother and fetus, with the microbial composition of the placenta and umbilical cord more closely resembling that of the fetal organs than the maternal intestine. Notably, compared with other adult RMs, there was a clear convergence between maternal and fetal microbiota, alongside distinct differences between the microbiota of adults and the fetus, which underscores the unique microbial profiles in fetal environments. Furthermore, the fetal microbiota displayed a less developed carbohydrate metabolism capacity than adult RMs. It also shared antibiotic resistance genes (ARGs) with both maternal and adult RM microbiomes, indicating potential vertical transmission. Comparative analysis of the metagenomes between the RM fetus and a human fetus revealed significant differences in microbial composition and genes, yet also showed similarities in certain abundant microbiota. Collectively, our results contribute to a more comprehensive understanding of the intrauterine microbial environment in macaques.

microbiology↗

bioRxiv2024

A bone-derived protein primes rapid visual escape via GPR37 receptor in a subpopulation of VTA GABAergic neurons

Rapid escape against visual threats is critical for survival. Whether it requires a permissive mechanism is unknown. Here, we show that osteocalcin (OCN), a protein produced by bone and persisted in the brain, primes rapid visual escape response by increasing excitability of VTA GABAergic neuron subpopulation via OCN-GPR37-cAMP-THIK-1 (K2P13.1) pathway. Knock-out of OCN or its receptor GPR37, and conditional knock-out of GPR37 in VTA GABAergic or glutamatergic neurons caused delayed escape. Reconstituting OCN-GPR37 signaling specifically in VTA was sufficient to restore normal response. Single-cell transcriptomics combined with electrophysiology showed that OCN decreases potassium currents in a subpopulation of VTA GABAergic neurons via GPR37-induced cAMP reduction and subsequent THIK-1 suppression. This elevation of excitability in VTA neuron subpopulation can be recapitulated by HM4Di, an inhibitory chemogenetic GPCR commonly used to suppress neuronal activity. Our study demonstrated that visual behavior requires a bone-derived protein that tunes electrophysiology of central nervous system neurons. Graph AbstractO_ST_ABSIn briefC_ST_ABSThe bone-brain axis regulates visual escape behavior. Osteocalcin (OCN), a small protein secreted by bone, plays a permissive role in rapid visual escape. This is achieved through GPR37 receptor expressed in a subpopulation of VTA GABAergic neurons. OCN-GPR37 signaling increases neuronal excitability by decreasing K+ current via THIK-1 channel suppression. HighlightsO_LIThe bone-derived protein osteocalcin and its receptor GPR37 in VTA are required for rapid visual escape response. C_LIO_LIGPR37 is expressed in a subpopulation of VTA GABAergic neurons and primes rapid visual escape. C_LIO_LIOsteocalcin-GPR37 signaling increases neuronal excitability by suppressing THIK-1 (K2P13.1) channel via cAMP reduction. C_LIO_LIActivation of HM4Di increases excitability of subpopulation of VTA GABAergic neurons and enhances rapid visual escape. C_LI O_FIG O_LINKSMALLFIG WIDTH=192 HEIGHT=200 SRC="FIGDIR/small/607510v1_ufig1.gif" ALT="Figure 1"> View larger version (50K): org.highwire.dtl.DTLVardef@1b7ef5dorg.highwire.dtl.DTLVardef@c3eea2org.highwire.dtl.DTLVardef@167dd75org.highwire.dtl.DTLVardef@1fc5613_HPS_FORMAT_FIGEXP M_FIG C_FIG

neuroscience↗

bioRxiv2024

LitGene: a transformer-based model that uses contrastive learning to integrate textual information into gene representations

Representation learning approaches leverage sequence, expression, and network data, but utilize only a fraction of the rich textual knowledge accumulated in the scientific literature. We present LitGene, an interpretable transformer-based model that refines gene representations by integrating textual information. The model is enhanced through a Contrastive Learning (CL) approach that identifies semantically similar genes sharing a Gene Ontology (GO) term. LitGene demonstrates accuracy across eight benchmark predictions of protein properties and robust zero-shot learning capabilities, enabling the prediction of new potential disease risk genes in obesity, asthma, hypertension, and schizophrenia. LitGenes SHAP-based interpretability tool illuminates the basis for identified disease-gene associations. An automated statistical framework gauges literature support for AI biomedical predictions, providing validation and improving reliability. LitGenes integration of textual and genetic information mitigates data biases, enhances biomedical predictions, and promotes ethical AI practices by ensuring transparent, equitable, open, and evidence-based insights. LitGene code is open source and also available for use via a public web interface at litgene.avisahuai.com.

bioinformatics↗

bioRxiv2024

Mechanism of neurodegeneration mediated by clonal inflammatory microglia

Langerhans cell Histiocytosis (LCH) and Erdheim-Chester disease (ECD) are clonal myeloid disorders, associated with MAP-Kinase activating mutations and an increased risk of neurodegeneration. Surprisingly, we found pervasive PU.1+ microglia mutant clones across the brain of LCH and ECD patients with and without neurological symptoms, associated with microgliosis, reactive astrocytosis, and neuronal loss. The disease predominated in the grey nuclei of the rhombencephalon, a topography attributable to a local proliferative advantage of mutant microglia. Presence of clinical symptoms was associated with a longer evolution of the disease and a larger size of PU.1+ clones (p= 0.0003). Genetic lineage tracing of PU.1+ clones suggest a resident macrophage lineage or a bone marrow precursor origin depending on patients. Finally, a CSF1R-inhibitor depleted mutant microglia and limited neuronal loss in mice suggesting an alternative to MAPK inhibitors. These studies characterize a progressive neurodegenerative disease, caused by clonal proliferation of inflammatory microglia (CPIM), with a decade(s)-long preclinical stage of incipient disease that represent a therapeutic window for prevention of neuronal death.

immunology↗

bioRxiv2024

Integrating in silico predictions with an engineered tissue assay identifies Perlecan as an age-perturbed re-quiescence cue for muscle stem cells

Skeletal muscle regeneration is mediated by resident muscle stem cells that produce progeny to repair or recreate muscle. Critical to this function is the ability to transition between states of proliferation and quiescence. This balancing act is disrupted with age, leading to eroded regenerative capacity. Notwistanding, mechanisms by which the regenerating niche directs MuSCs return to the dormant state are largely unknown. Since single-cell RNAseq methods exclude the analysis of multinucleated cells, we generated single-nuclei RNAseq datasets of regenerating muscle to capture the full breadth of myogenic progression. With this, we uncovered new transition states between differentiating myocytes and syncytial multinucleated cells. Using cell communication inference tools, we highlighted receptor-ligand interactions between MuSCs and fusing nuclei. We leveraged a bespoke biomimetic 3D niche that induces MuSC quiescence, to filter the predicted interactions using a Cas9-based functional genomics approach. We found the proteoglycan Perlecan (Hspg2) promotes MuSC re-quiescence. Hspg2 silencing in vivo, during muscle regeneration, induced an aging-like phenotype and perturbed MuSC re-quiescence. Notably, the temporal profile and overall levels of Perlecan were altered with age. Exogenous supplementation with Endorepellin (truncated Perlecan) rescued MuSC decline following aged muscle regeneration, offering a new therapeutic target. Thus, coupling in silico predictions with a 3D in vitro assay followed by in vivo investigations revealed a previously inaccessible window of biology; that spatiotemporal coordination of MuSC re-quiescence is directed by fusing myonuclei.

cell biology↗

bioRxiv2024

A potent and selective reaction hijacking inhibitor of Plasmodium falciparum tyrosine tRNA synthetase exhibits single dose oral efficacy in vivo

The Plasmodium falciparum cytoplasmic tyrosine tRNA synthetase (PfTyrRS) is an attractive drug target that is susceptible to reaction-hijacking by AMP-mimicking nucleoside sulfamates. We previously identified an exemplar pyrazolopyrimidine ribose sulfamate, ML901, as a potent pro-inhibitor of PfTyrRS. Here we examined the stage specificity of action of ML901, showing very good activity against the schizont stage, but lower trophozoite stage activity. We explored a series of ML901 analogues and identified ML471, which exhibits improved potency against trophozoites and enhanced selectivity against a human cell line. Additionally, it has no inhibitory activity against human ubiquitin-activating enzyme (UAE) in vitro. ML471 exhibits low nanomolar activity against asexual blood stage P. falciparum and potent activity against liver stage parasites, gametocytes and transmissible gametes. It is fast-acting and exhibits a long in vivo half-life. ML471 is well-tolerated and shows single dose oral efficacy in the SCID mouse model of P. falciparum malaria. We confirm that ML471 is a pro-inhibitor that is converted into a tight binding Tyr-ML471 conjugate by the PfTyrRS enzyme. A crystal structure of the PfTyrRS/ Tyr-ML471 complex offers insights into improved potency, while molecular docking into UAE provides a rationale for improved selectivity.

biochemistry↗

bioRxiv2024

Equip Fusobacterium nucleatum genetic tool kits with compatible shuttle vectors and engineered intermediatory E. coli strains for enhanced transformation efficiency

Fusobacterium nucleatum, an oral microbe, is implicated in various human diseases, including oral-related diseases and tumors. However, efficient transformation was only achieved in limited strains of this bacterium. The challenges in conducting molecular level investigations of most strains due to their genetic intractability have hindered the biological studies of F. nucleatum. The restriction-modification (RM) systems is one of the known obstacles for efficient DNA transformation. Here, we used single molecule real time sequencing to elucidate the RM recognition sites and the corresponding methyltransferases (MTases) in two F. nucleatum strains. Based on the identified MTases, we engineered intermediatory E. coli host strains to bypass the RM systems, and showed that the plasmids harbored by these intermediatory strains can be efficiently electro-transformed, reaching 5000 transformants per microgram plasmids, paving the way for the development of efficient genetic modification tools. Furthermore, we successfully demonstrated that the conjugation-based DNA delivery to F. nucleatum can bypass the requirement of MTase methylations. By exploring the native plasmids from F. nucleatum, we identified new backbones for construction of shuttle vectors and established a dual-plasmid system for the first time, offering new avenues for genetic manipulation in this bacterium. Additionally, we evaluate promoters with variable strengths with a luciferase-based reporter system in F. nucleatum, providing valuable insights for future gene editing studies in bacterium and contributing to our understanding of its pathogenesis. All the tools developed in this study was shared via the WeKwikgene (https://wekwikgene.wllsb.edu.cn/). Impact StatementFusobacterium nucleatum, a key opportunistic pathogen implicated in periodontal diseases, rheumatoid arthritis, and tumors, presents significant challenges due to its limited transformation efficiency and lack of gene-editing tools. In this study, we present an advancement -a streamlined and robust pipeline that enhances transformation efficiency by approximately 103-fold in F. nucleatum, reaching 5000 CFU per microgram plasmids. This represents a significant breakthrough, marking the first report to achieve such a remarkable improvement in transformation efficiency in this pathogen. This improvement paves the way for the genome-wide level mutagenesis study in this bacterium.

microbiology↗

bioRxiv2024

Metabolic conservation by protein quality control in Campylobacter jejuni underlies the antibiotic tolerance

Bacterial persistence enables survival during lethal antibiotic exposure and is implicated in recurrent infections, yet the physiology underlying bacterial persistence in many pathogens remains poorly defined. Here we show that exposure of Campylobacter jejuni to ampicillin or ciprofloxacin generates an antibiotic-persistent subpopulation. Rather than undergoing global metabolic shutdown, persister cells adopted a metabolically constrained state characterized by selective maintenance of oxidative phosphorylation and bioenergetic metabolism through coordinated proteostasis control. The ATP-dependent protease ClpP was essential for entry into this persistent state. Loss of ClpP disrupted proteostasis of the electron transport chain, specifically impaired bd-like terminal oxidase integrity, and reduced survival in vivo and in macrophages. These findings identify ClpP-dependent maintenance of redox and bioenergetic homeostasis as critical determinants of C. jejuni persistence and highlight metabolic remodeling as a defining feature of antibiotic tolerance. These insights may inform future therapeutic strategies aimed at disrupting persistence and improving antibiotic efficacy.

microbiology↗

bioRxiv2024

Quantifying social roles in multi-animal videos using subject-aware deep-learning

Analyzing social behaviors is critical for many fields, including neuroscience, psychology, and ecology. While computational tools have been developed to analyze videos containing animals engaging in limited social interactions under specific experimental conditions, automated identification of the social roles of freely moving individuals in a multi-animal group remains unresolved. Here we describe a deep-learning-based system - named LabGym2 - for identifying and quantifying social roles in multi-animal groups. This system uses a subject-aware approach: it evaluates the behavioral state of every individual in a group of two or more animals while factoring in its social and environmental surroundings. We demonstrate the performance of subject-aware deep-learning in different species and assays, from partner preference in freely-moving insects to primate social interactions in the field. Our subject-aware deep learning approach provides a controllable, interpretable, and efficient framework to enable new experimental paradigms and systematic evaluation of interactive behavior in individuals identified within a group.

animal behavior and cognition↗

bioRxiv2024

A unique mechanism of snRNP core assembly

The assembly of spliceosomal snRNP cores involves seven Sm proteins (D1/D2/F/E/G/D3/B) forming a ring around each snRNA and typically requires several essential assembly chaperones, particularly the SMN-Gemins complex implicated in spinal muscular atrophy (SMA). Strikingly, in budding yeast, snRNP core assembly only involves Brr1, a nonessential homolog of Gemin2. To unravel this enigma, we systematically investigated snRNP core assembly in budding yeast using biochemical and genetic approaches. We discovered two distinct pathways in budding yeast: chaperone-mediated and direct. The chaperone-mediated pathway involves two proteins, Brr1 and a novel protein, Lot5, but is inefficient. Lot5 binds D1/D2/F/E/G to form a heterohexameric ring (6S). Brr1 binds D1/D2/F/E/G and 6S but cannot displace Lot5 to facilitate assembly. Disruption of both BRR1 and LOT5 genes caused mild growth retardation, but LOT5 overexpression substantially impeded growth. The direct pathway uniquely involves F/E/G as a trimer and a stable D1/D2/F/E/G intermediate complex, explaining the non-essentiality of assembly chaperones. These findings unveil a unique assembly mechanism of snRNP cores, illuminate the evolution of assembly chaperones, and suggest avenues for studying SMA pathophysiology.

molecular biology↗

bioRxiv2024

Unravelling the progression of the zebrafish primary body axis with reconstructed spatiotemporal transcriptomics

Elucidating the spatiotemporal dynamics of gene expression is essential for understanding complex physiological and pathological processes. Traditional technologies like in situ hybridization (ISH) and immunostaining have been restricted to analyzing expression patterns of a limited number of genes. Spatial transcriptomics (ST) has emerged as a robust alternative, enabling the investigation of spatial patterns of thousands of genes simultaneously. However, current ST methods are hindered by low read depths and limited gene detection capabilities. Here, we introduce Palette, a pipeline that infers detailed spatial gene expression patterns from bulk RNA-seq data, utilizing existing ST data as only reference. This method identifies more precise expression patterns by smoothing, imputing and adjusting gene expressions. We applied Palette to construct the Danio rerio SpatioTemporal Expression Profiles (DreSTEP) by integrating 53-slice serial bulk RNA-seq data from three developmental stages with existing ST references and 3D zebrafish embryo images. DreSTEP provides a comprehensive cartographic resource for examining gene expression and spatial cell-cell interactions within zebrafish embryos. Utilizing machine learning-based screening, we identified key morphogens and transcription factors (TFs) essential for anteroposterior (AP) axis development and characterized their dynamic distribution throughout embryogenesis. In addition, among these TFs, Hox family genes were found to be pivotal in AP axis refinement. Their expression was closely correlated with cellular AP identities, and hoxb genes may act as central regulators in this process.

developmental biology↗

bioRxiv2024

The m6A reader IGF2BP3 promotes gastric cancer progression via increasing the expression of FBXO32 protein

N6-methyladenosine (m6A) represents the most prevalent chemical modification on eukaryotic mRNA, with an accumulating body of literature indicating its pivotal significance in the pathogenesis of human cancers. Nevertheless, the precise molecular interplay between the m6A reader protein IGF2BP3 and gastric cancer remains to be thoroughly delineated. Our study uncovered that the expression of IGF2BP3 in gastric cancer tissues is markedly elevated in comparison to adjacent normal tissues, and this upregulation is tightly correlated with the incidence of lymph node metastasis, more advanced TNM stages, and deeper invasion depth of tumor in patients. In vitro experiments demonstrated that IGF2BP3 potentiates the proliferative, migratory, and invasive capacities of gastric cancer cells, while concurrently inhibiting apoptosis and augmenting the intracellular levels of aerobic glycolysis. In vivo experiments revealed that IGF2BP3 contributes to the growth of gastric cancer. Mechanistically, IGF2BP3 can increase the expression of FBXO32 protein by recognizing and binding to the m6A binding site on FBXO32 mRNA and further activate the downstream cGMP-PKG signaling pathway, thereby modulating various biological functions of gastric cancer cells and ultimately promoting the progression of gastric cancer. In summary, our findings suggest that IGF2BP3 upregulates the expression of FBXO32 protein in an m6A dependent manner and subsequently activates the cGMP-PKG signaling pathway, ultimately leading to the onset and progression of gastric cancer. Consequently, the targeting of the IGF2BP3/FBXO32/cGMP-PKG axis emerges as a promising therapeutic modality for the treatment of gastric cancer.

cancer biology↗

bioRxiv2024

Path-based reasoning in biomedical knowledge graphs

Understanding complex interactions in biomedical networks is crucial for advancements in biomedicine, but traditional link prediction (LP) methods are limited in capturing this complexity. Representation-based learning techniques improve prediction accuracy by mapping nodes to low-dimensional embeddings, yet they often struggle with interpretability and scalability. We present BioPathNet, a novel graph neural network framework based on the Neural Bellman-Ford Network (NBFNet), addressing these limitations through path-based reasoning for LP in biomedical knowledge graphs. Unlike node-embedding frameworks, BioPathNet learns representations between node pairs by considering all relations along paths, enhancing prediction accuracy and interpretability. This allows visualization of influential paths and facilitates biological validation. BioPathNet leverages a background regulatory graph (BRG) for enhanced message passing and uses stringent negative sampling to improve precision. In evaluations across various LP tasks, such as gene function annotation, drug-disease indication, synthetic lethality, and lncRNA-mRNA interaction prediction, BioPathNet consistently outperformed shallow node embedding methods, relational graph neural networks and task-specific state-of-the-art methods, demonstrating robust performance and versatility. Our study predicts novel drug indications for diseases like acute lymphoblastic leukemia (ALL) and Alzheimers, validated by medical experts and clinical trials. We also identified new synthetic lethality gene pairs and regulatory interactions involving lncRNAs and target genes, confirmed through literature reviews. BioPathNets interpretability will enable researchers to trace prediction paths and gain molecular insights, making it a valuable tool for drug discovery, personalized medicine and biology in general.

bioinformatics↗

bioRxiv2024

Systemic delivery of murine SOD2 mRNA to experimental abdominal aortic aneurysm mitigates expansion and rupture

BackgroundOxidative stress is implicated in the pathogenesis and progression of abdominal aortic aneurysm (AAA). Antioxidant delivery as a therapeutic for AAA is of substantial interest although clinical translation of antioxidant therapy has met with significant challenges due to limitations in achieving sufficient antioxidant levels at the site of AAA. We posit that nanoparticle-based approaches hold promise to overcome challenges associated with systemic administration of antioxidants. MethodsWe employed a peptide-based nanoplatform to overexpress a key modulator of oxidative stress, superoxide dismutase 2 (SOD2). The efficacy of systemic delivery of SOD2 mRNA as a nanotherapeutic agent was studied in two different murine AAA models. Unbiased mass spectrometry-enabled proteomics and high-dimensional bioinformatics were used to examine pathways modulated by SOD2 overexpression. ResultsThe murine SOD2 mRNA sequence was mixed with p5RHH, an amphipathic peptide capable of delivering nucleic acids in vivo to form self-assembled nanoparticles of [~]55 nm in diameter. We further demonstrated that the nanoparticle was stable and functional up to four weeks following self-assembly when coated with hyaluronic acid. Delivery of SOD2 mRNA mitigated the expansion of small AAA and largely prevented rupture. Mitigation of AAA was accompanied by enhanced SOD2 protein expression in aortic wall tissue. Concomitant suppression of nitric oxide, inducible nitric oxide synthase expression, and cell death was observed. Proteomic profiling of AAA tissues suggests that SOD2 overexpression augments levels of microRNAs that regulate vascular inflammation and cell apoptosis, inhibits platelet activation/aggregation, and downregulates mitogen-activated protein kinase signaling. Gene set enrichment analysis shows that SOD2 mRNA delivery is associated with activation of oxidative phosphorylation, lipid metabolism, respiratory electron transportation, and tricarboxylic acid cycle pathways. ConclusionsThese results confirm that SOD2 is key modulator of oxidative stress in AAA. This nanotherapeutic mRNA delivery approach may find translational application in the medical management of small AAA and the prevention of AAA rupture.

cell biology↗

bioRxiv2024

Unraveling Lineage Roadmaps and Cell Fate Determinants to Postnatal Neural Stem Cells and Ependymal cells in the Developing Ventricular Zone

The ventricular zone (VZ) is made up of adult neural stem cells (NSCs) and multi-ciliated ependymal cells (EPCs). Both NSCs and EPCs are derived from radial glial cells (RGCs). To date, the transcriptomic dynamics and the molecular mechanisms guiding the cell fate commitment during the differentiation remain poorly understood. In this study, we analysed the developing VZ at the single-cell resolution and identified three distinct cellular states of RGCs: bipotent glial progenitor cells (bGPCs), neonatal NSC-neuroblasts (nNSC-NBs) and neonatal EPCs (nEPCs). The differentiation from bGPCs to nNSC-NBs and nEPCs forms a continuous bifurcating trajectory. Further molecular analysis along the NSC branch unveiled a novel intermediate state of cells expressing oligodendrocyte precursor cell (OPC) and neuroblast (NB) marker genes. Several transcription factors (TFs) were proved to be essential for the EPC-lineage differentiation, with TFEB emerging as a key regulator dictating the bGPC fate. The activation of TFEB promoted differentiation towards NSC-NBs while restrained the trajectory towards EPCs. Our findings offer detailed insights into further understanding VZ development and lay the groundwork for investigating potential therapeutic strategies against VZ-related disorders, such as hydrocephalus and neurodegenerative diseases (NDDs).

genomics↗

bioRxiv2024

Reversible kink instability drives ultrafast jumping in nematodes and soft robots

Entomopathogenic nematodes (EPNs) exhibit a bending-elastic instability, or kink, before becoming airborne, a feature hypothesized but not proven to enhance jumping performance. Here, we provide the evidence that this kink is crucial for improving launch performance. We demonstrate that EPNs actively modulate their aspect ratio, forming a liquid-latched closed loop over a slow timescale O(1 s), then rapidly open it O (10 {micro}s), achieving heights of 20 body lengths (BL) and generating [~] 104 W/Kg of power. Using jumping nematodes, a bio-inspired Soft Jumping Model (SoftJM), and computational simulations, we explore the mechanisms and implications of this kink. EPNs control their takeoff direction by adjusting their head position and center of mass, a mechanism verified through phase maps of jump directions in simulations and SoftJM experiments. Our findings reveal that the reversible kink instability at the point of highest curvature on the ventral side enhances energy storage using the nematodes limited muscular force. We investigated the impact of aspect ratio on kink instability and jumping performance using SoftJM, and quantified EPN cuticle stiffness with AFM, comparing it with C. elegans. This led to a stiffness-modified SoftJM design with a carbon fiber backbone, achieving jumps of [~]25 BL. Our study reveals how harnessing kink instabilities, a typical failure mode, enables bidirectional jumps in soft robots on complex substrates like sand, offering a novel approach for designing limbless robots for controlled jumping, locomotion, and even planetary exploration.

biophysics↗