Biology subjects

Zhang, M.

Publications and source records attributed to Zhang, M..

At least 127 records · Page 7Linked to original sources

bioRxiv2026

Calcium directs actin assembly via allosteric activation of formin INF2

Calcium signals spatiotemporally orchestrate cytoskeletal dynamics, typically through Rho GTPase-mediated signaling cascades, yet the direct molecular transducers that convert local calcium transients into spatially controlled actin assembly have remained elusive. Here, we uncover a structure-based mechanism by which calcium-bound calmodulin (Ca2+-CaM) directly activates formin INF2 to drive actin assembly. We demonstrate that Ca2+-CaM binds to the diaphanous inhibitory domain (DID) of INF2 with nanomolar affinity, inducing allosteric conformational changes that sterically disrupt INF2 autoinhibition. The unexpected bipartite Ca2+-CaM binding interface on INF2 enables ultrasensitive decoding of local calcium microdomains, such as ER-mitochondrial contacts, where activated INF2 promotes actin polymerization to facilitate mitochondrial fission. We further show that the Charcot-Marie-Tooth disease-associated INF2 R91G mutation enhances Ca2+-CaM binding via optimized interfacial dynamics, suggesting a gain-of-function disease mechanism. Our work establishes the Ca2+-CaM-INF2 axis as a direct molecular transducer linking spatial calcium signals to actin-dependent organelle dynamics, defining a Rho-GTPase-independent paradigm for calcium-cytoskeleton communication, with broad implications for INF2-linked pathologies.

biochemistry↗

bioRxiv2026

The ZmHEAT1/ZmKAKU42-ZmNCH1 module regulates heat stress tolerance by modulating nuclear envelope structure in maize

Heat stress threatens maize production. Through a genome-wide association study using pollen viability decline rate as a phenotype, we identified ZmHEAT1, encoding the nuclear envelope protein ZmKAKU41, as a key regulator of thermotolerance. ZmHEAT1 positively regulates heat tolerance at seedling and reproductive stages, with its overexpression improving thermotolerance and its knockout reducing pollen viability and yield under high temperatures. ZmHEAT1 interacts with its homolog ZmKAKU42 and the nucleoskeleton protein ZmNCH1 to form a complex at the nuclear envelope. Mutants lacking ZmHEAT1 or ZmKAKU42 exhibit increased nuclear envelope damage under heat stress, along with repressed expression of key heat shock protein genes (e.g., HSP90-2, HSP17.4). This work establishes the ZmHEAT1/ZmKAKU42-ZmNCH1 complex as a critical guardian of nuclear integrity and heat response, providing a valuable genetic resource for breeding heat-tolerant maize varieties. One-sentence summaryModulation of the nuclear envelope structure in maize is involved in heat stress tolerance.

molecular biology↗

bioRxiv2026

A holocentric pangenome links karyotype evolution to meiotic recombination

Chromosomal fissions, fusions and whole-genome duplications propel genome evolution, yet their impact on meiotic recombination is obscured by the centromere constraint, since in monocentric species most large rearrangements are lethal1-4. Holocentric organisms, which distribute kinetochore activity along the entire chromosome, overcome this barrier and therefore offer a unique window onto the interplay between karyotype change and crossover control2. We assembled chromosome-scale genomes for 20 holocentric Rhynchospora species (including 56 haplotypes), representing all major clades of the genus, featuring satellite-based holocentromeres5,6, and integrated single-gamete crossover maps, high-resolution meiotic synapsis immunocytochemistry and Hi-C chromatin architecture. Breakpoint analysis shows that holocentromeric Tyba satellite arrays6,7 are recurrent hotspots for both chromosome fusions and fissions, contributing to the genuss extraordinary chromosome number variation from 2n = 4 to 36. Crossover landscapes group into two apparent modes: strongly distal-biased versus irregularly distributed, which is correlated with divergent patterns of synapsis elongation. Moreover, crossover number scales with chromosome count and meiotic axis length. In contrast, crossover density per megabase is inversely related to chromosome length and to chromatin-loop size. We propose that chromosome fissions create karyotypes with smaller chromosomes folded into shorter loops, thereby increasing the axial substrate accessible for double-strand break formation and elevating recombination frequency. Together, our results provide a structural link between large-scale structural chromosome evolution and meiotic recombination through coupled changes in chromosome number, size, loop geometry, and synapsis dynamics.

genomics↗

bioRxiv2026

Sex without crossovers mimics clonal reproduction in the holocentric plant Rhynchospora tenuis

Meiotic recombination ensures accurate chromosome segregation and promotes genetic diversity by generating crossovers between homologous chromosomes1. While essential in most sexually reproducing organisms, recombination is variably regulated and can be absent in some lineages, a condition known as achiasmy2. However, obligate achiasmy in both sexes of a sexual species has not been previously documented. Here, we investigate the beak-sedge Rhynchospora tenuis, a holocentric plant with the lowest known chromosome number among flowering plants (n = 2) and inverted meiosis3. Using chromosome-scale genome assemblies from nine accessions, molecular cytogenetics, immunocytochemistry, high-throughput single-gamete sequencing and whole-genome sequencing of controlled crosses, we show that R. tenuis undergoes obligate, genome-wide achiasmy in both male and female meiosis. Despite normal early meiotic axis formation, synapsis fails, crossovers are not detected cytologically or genetically, and univalents persist at metaphase I. Extensive haplotype-specific accumulation of transposable elements (TEs) generates segregation distortion (e.g. meiotic drive), favouring the transmission of larger, TE-rich chromosomes. Remarkably, sexual reproduction is retained with fertilisation producing viable seeds only when translocation-compatible gametes meet, indicating strong post-meiotic selection that eliminates incompatible homozygous combinations. As a result, all surviving offspring are genetically identical to the maternal genotype, effectively restoring heterozygosity each generation and mimicking clonal reproduction. We propose that the combined effects of recombination loss, low chromosome number, holocentricity, inverted meiosis, and selective transmission of longer chromosomes enable faithful segregation and clonal-like inheritance despite sexual reproduction. These findings challenge the boundary between sex and clonality, revealing a unique evolutionary strategy linking genome architecture, recombination loss, and transmission bias.

evolutionary biology↗

bioRxiv2026

Pangenome analysis reveals the evolutionary dynamics of repeat-based holocentromeres

Centromeres are essential for chromosome segregation, yet their organisation and evolution remain poorly understood in holocentric species, where kinetochore activity is distributed along entire chromosomes1,2. While monocentric centromeres are often structured by megabase-sized satellite arrays3-5, the role of repetitive DNA in holocentric systems remains enigmatic. Here, we analyse the dynamics of centromeric Tyba satellite DNA repeats and transposable elements across a chromosome-scale pangenome comprising 56 long-read haplotype assemblies from 20 Rhynchospora species6,7, a plant genus with repeat-based holocentromeres8,9. We identify over 4.6 million monomers of the Tyba satellite repeat, arranged into 43,400 discrete arrays that span all chromosomes. CENH3 ChIP-seq reveals that, unexpectedly, the same Tyba satellite defines holocentromere across the entire genus, demonstrating deep conservation of centromeric DNA over over 40 million years despite extensive karyotype evolution and centromere array turnover. We show that Tyba arrays function as modular centromeric units whose number and spacing, but not size, scale with chromosome length. Tyba sequence diversity recapitulates species phylogeny, while higher-order repeat formation and antagonism with transposable elements shape array turnover. A novel synteny-aware algorithm reveals rapid gain, loss, and rearrangement of arrays across homologous chromosomes. Using cytogenetics and polymer simulations, we demonstrate that inter-array spacing governs chromatin loop length and chromatid thickness, linking repeat-based holocentromere organisation directly to chromosome mechanics. Our findings uncover a scalable, modular logic for holocentromere function and establish a framework for understanding the plasticity of repeat-based centromere evolution and genome architecture in eukaryotes.

genomics↗

bioRxiv2026

Unlocking Bacterial Cellulose Functionalisation: Comparative Genetic and Co-Culture Strategies in Komagataeibacter

Bacterial cellulose (BC) is produced by diverse bacterial species, including members of the genus Komagataeibacter, and has emerged as a potential sustainable alternative to conventional materials such as plastics and leather. Its production by bacteria is rapid and easily scalable, and via genetic modifications or culturing the bacteria with other microbes, it is possible to rationally enhance the BC that is produced, for example by adding functional components. Here, we systematically evaluated BC functionalization strategies, including genetic engineering and co-culturing with other engineered microbes across the most widely used Komagataeibacter species: K. rhaeticus, K. xylinus, K. medellinensis and K. sucrofermentans. We established that all tested strains are amenable to DNA transformation and capable of expressing heterologous genes from identical genetic constructs. However, we identified species-specific differences in heterologous gene expression, cellulose production in varying environmental conditions and in the abilities of the strains to co-culture with Escherichia coli. Additionally, we demonstrated that all these cellulose-producing bacteria can establish functional symbiotic co-cultures with yeast. While inter-species variations in heterologous gene expression and co-culture dynamics are evident, BC modification through genetic engineering and co-culturing strategies remains achievable across all tested Komagataeibacter species. Our work provides a comparative framework to guide researchers in selecting optimal species based on their specific application requirements.

synthetic biology↗

bioRxiv2026

Asymmetric Division in a Two-Cell-Like State Rejuvenates Embryonic Stem Cells

A fundamental question in biology is whether cellular aging is inevitable. Embryonic stem cells (ESCs) challenge this paradigm as rare normal cells capable of indefinite in vitro passage. However, the mechanisms underlying ESC lineage immortality remain unresolved. Using long-term live-cell imaging to follow fates of single ESCs, we show here that ESC lineage renewal is achieved through sporadic entry into a state characterized by the expression of two-cell embryo-specific markers. During this state, cells undergo asymmetric divisions, segregating accumulated DNA damage into one daughter lineage destined for elimination, while producing a second lineage that reverts to the pluripotent state. Importantly, the latter lineage exhibits signs of rejuvenation, including reduced DNA damage and enhanced chimeric efficiency. These findings underscore the crucial role of asymmetric cell division in maintaining the long-term health of the ESC lineage against mounting damage within individual cells, a potential model for studying cellular aging and rejuvenation in mammalian cells.

cell biology↗

bioRxiv2026

ToolsGenie 2.0: A Scalable and Extensible Multi-Agent System for Bioinformatics Automation

The rapid expansion of biomedical data necessitates efficient bioinformatics tools, yet conventional workflows rely heavily on manual dependencies, hindering scalability and broader adoption. Building on the foundation of ToolsGenie 1.0, we introduce ToolsGenie 2.0, a multi-agent AI framework that automates bioinformatics analyses through natural language queries and file inputs. ToolsGenie 2.0 addresses the growing need for customizable analyses by offering extensibility, reproducibility, improved accuracy, and ease of use. It incorporates a ReAct-based architecture with dual-layer extensibility for sub-agents and specialized tools, along with dynamic Docker image selection for automated, sandboxed, and secure environment management. Rigorous benchmarking shows that ToolsGenie 2.0 achieves 68.6% accuracy on an in-house dataset and 48.3% accuracy on BixBench, demonstrating competitive performance across diverse evaluation settings. These innovations position ToolsGenie 2.0 as a versatile platform for broadening access to bioinformatics in both research and clinical contexts. ToolsGenie 2.0 is available on the PromptBio platform (platform.promptbio.ai).

bioinformatics↗

bioRxiv2026

Abalone genomics reveals an ancient asymmetry axis and the multifunctionality of the mantle

Gastropod diversification represents one of the most spectacular evolutionary radiations, underpinned by a fundamentally asymmetric body plan and diverse pigmentation patterns. To understand the genetic underpinnings of these cardinal traits, we constructed a chromosome-level genome assembly for the rainbow abalone, Haliotis iris. Integrating systematic genomics, histoembryology, and molecular assays, we uncover an ancient regulatory axis, conserved for over 544 million years, in which the long non-coding RNA lncRNA1 functions as a competing endogenous RNA to shield pitx transcripts from miRNA-mediated degradation, thereby driving the establishment of asymmetric body patterning, including the mantle. Furthermore, we identify a wnt-mitf-tyr cascade as the driver of melanogenesis and demonstrate that the mantle is the primary site of melanin synthesis. Concurrently, we reveal the mantle as a multifunctional organ possessing mechanosensory capabilities. These findings elucidate the ancient genetic toolkit governing trait evolution in gastropods. TeaserA deeply conserved RNA switch directs gastropod body plans and reveals the mantles hidden talents.

genomics↗

bioRxiv2026

A plug-and-play ROI imaging module and deep-learning denoising framework extend three-photon microscopy to 1.7 mm depth

Three-photon microscopy (3PM) has extended optical imaging beyond the reach of two-photon microscopy (2PM), but its practical depth remains far below theoretical predictions because of low photon efficiency and severe noise contamination. Here we present an integrated hardware and software solution that addresses these limitations. We developed a plug-and-play region-of-interest (ROI) imaging module that selectively excites neuron-occupied regions to improve power efficiency and reduce photothermal stress. The module incorporates frame-partitioned accumulative (FPA) imaging for high signal-to-noise ratio (SNR) structural acquisition, automated neuron segmentation, and motion-robust registration for stable recordings. Complementing this, OptiCal is a cascaded deep-learning framework that removes mixed noise including periodic, motion-induced, and random components. Together, these innovations enable high-fidelity imaging to 1.7 mm depth, extending the practical limit of 3PM by about 400 {micro}m while maintaining low excitation power. Our results reveal reliable calcium activity and behavior-correlated dynamics in deep medial prefrontal cortex of awake mice.

neuroscience↗

bioRxiv2025

Focused ultrasound programmed characteristic NIR-IIb lanthanide mechanoluminescence for high sensitivity bioimaging in vivo

Optical imaging techniques for biodetection are hindered by limited sensitivity and resolution in deep tissues, arising primarily from photon scattering and endogenous autofluorescence. Herein, we report a focused ultrasound (FUS) programmable NIR-IIb emissive mechanoluminescent nanoparticle for in vivo bioimaging. Specifically, CaZnOS nanoparticles co-doped with Mn2+ and Er3+ were engineered to exhibit mechanoluminescence (ML) emission peaked at 1550 nm. FUS stimulation elicits ML without the need for optical excitation, thereby enabling deep-tissue imaging devoid of background interference from excitation light. By modulating the excitation frequency of FUS, ML can be programmed as a characteristic signal. Integrated with a Fourier frequency-transform identification reconstruction (FFIR) algorithm, the specific ML signals can be detected with high sensitivity, reaching sub-millimeter spatial resolution and markedly enhanced signal-to-background ratios compared to conventional photoluminescence-based approaches. By macrophage internalization of the ML nanoparticles to yield functional macrophage-nanoparticle (FMNs), a ultralow detection limit of 10 cells can be achieved. In murine tumor models, the FMNs facilitated real-time monitoring of early-stage tumor progression, underscoring their biocompatibility and translational promise for high-precision diagnostics in deep-seated neoplasms.

bioengineering↗

bioRxiv2025

Kilohertz-rate two-photon voltage imaging of population dynamics in vivo

Understanding how neural circuits compute requires capturing voltage dynamics across large neuronal populations with millisecond resolution in vivo. However, two-photon voltage imaging remains fundamentally limited by a trade-off among imaging speed, field of view, and excitation efficiency. We introduce HS2PM, a hybrid scanning two-photon microscope that overcomes this bottleneck, enabling kilohertz-rate imaging over a 650 x 524 m2 field of view at single-cell resolution while preserving the photon efficiency of single-point excitation. HS2PM stably records deep-layer membrane potentials from over 160 neurons simultaneously, with minimal photobleaching and phototoxicity. It resolves both spikes and subthreshold voltage dynamics in vivo, revealing how these jointly shape sensory adaptation and population coding. Beyond voltage imaging, HS2PM supports high-speed fluorescence lifetime and vascular flow imaging, establishing a multimodal platform for dissecting fast circuit dynamics with precision previously inaccessible to optical methods.

neuroscience↗

bioRxiv2025

PocketX: Preference Alignment for Protein Pockets Design through Group Relative Policy Optimization

Designing protein pockets that target specific ligands is crucial for drug discovery and enzyme engineering. Although deep generative models show promise in proposing high-quality pockets, they are usually trained purely to match the data distribution and therefore overlook key biophysical properties, such as binding affinity, expression, and solubility, that ultimately determine developability and success. We introduce PocketX, an online reinforcement learning framework that explicitly aligns a generative model with desired biophysical properties. The framework first trains a base model that co-designs pocket structures and sequences conditioned on a target ligand, and then fine-tunes this model with Group Relative Policy Optimization (GRPO) to reward the desired attributes. Because GRPO employs group-relative rewards, it produces lower-variance policy updates, resulting in more stable and efficient learning than competing alignment strategies. Evaluated on the CrossDocked2020 benchmark, PocketX surpasses existing methods in metrics such as binding energy and evolutionary plausibility. Ablation studies further show that GRPO outperforms alternative alignment strategies, including Direct Preference Optimization (DPO), confirming GRPOs effectiveness for biophysical property alignment.

bioinformatics↗

bioRxiv2025

LARP6 Promotes Features of Plaque Stability and Smooth Muscle Cell Survival in Atherosclerosis

IntroductionAcute plaque rupture or erosion followed by luminal thrombosis is a major cause of myocardial infarction and sudden cardiac death. Vulnerable plaques are characterized by a thin fibrous cap and reduced numbers of smooth muscle cells (SMCs). SMCs are essential for plaque stability, as they synthesize collagen and support fibrous cap structure. Our previous work demonstrated that insulin-like growth factor-1(IGF-1) enhances plaque stability and upregulates La ribonucleoprotein domain family member 6 (Larp6), a collagen mRNA-binding protein in SMCs. However, the specific role of Larp6 in atherosclerotic plaque stability remains undefined. MethodsIn vitro, human aortic SMCs (hAoSMCs) were used to investigate the molecular mechanism underlying IGF-1 regulation of LARP6. Using the Myh11 promotor we generated SMC specific Larp6 overexpression mice on an ApoE-/- background (SMC-Larp6) to assess effects on plaque stability. Bulk RNA sequencing data from human atherosclerotic plaques (GSE120521) were analyzed to compare stable and vulnerable plaques. ResultsIGF-1 regulates LARP6 through phosphorylation and downregulation of microRNAs. Plaques from SMC-Larp6 mice exhibited a significantly higher collagen content, accompanied by a thicker fibrous cap and a smaller necrotic core, increased presence of SMCs, without changes in overall plaque burden compared to controls. LARP6 overexpression in hAoSMCs significantly increased cell proliferation and survival under oxidative stress and promoted collagen accumulation by enhancing collagen synthesis. RNA sequencing analysis of human atherosclerotic plaques revealed reduced expression of LARP6 and downregulation of extracellular matrix-related pathways in unstable plaques, underscoring the clinical relevance of these findings. ConclusionsLarp6 overexpression promotes SMC survival, collagen synthesis and features of plaque stability under atherosclerotic conditions. These findings suggest that Larp6 is a potential therapeutic target for stabilization of atherosclerotic plaques.

pathology↗

bioRxiv2025

Two Small Proteins Enable N2O Reduction in Acidic Environments

Denitrifying bacteria are major contributors to nitrous oxide (N2O) emissions, which rise with global soil acidification, likely because low pH impairs maturation of the periplasmic enzyme N2O reductase (NosZ) in most bacteria. While some bacteria can reduce N2O under acidic conditions, the underlying mechanism remain unclear. Here, we isolated bacteria from acidic soils and identified strains that efficiently reduce N2O at low pH. They carry two novel proteins, NosP and NosQ, along with NosZ clade I. Functional analyses of deletion mutants demonstrated that NosP and NosQ are essential for the maturation of NosZ at low pH, but are not required at circumneutral pH. Cryo-EM analysis indicates that NosPQ forms a protective complex with NosZ, safeguarding its maturation under acidic conditions. Metagenomic analysis shows that nosPQ genes are widely distributed across diverse bacterial taxa and soil types. Our findings reveal a key molecular adaptation mechanism for N2O reduction in acidic environments and provide valuable insights for developing efficient N2O mitigation strategies.

biochemistry↗

bioRxiv2025

miRISC inhibition causes mitotic defects and synergizes with genotoxic agents in cancers

Although individual microRNAs (miRNAs) can have tumorigenic or tumor-suppressive properties, their overall role in cancer remains controversial. Here, we show that cancer tissues and cell lines are characterized by preferential accumulation of the high-molecular-weight miRNA-induced silencing complex (HMWR), the functionally active form of the effector complex responsible for miRNA-mediated gene repression. Experimentally induced disassembly of the HMWR impairs the growth of human tumor xenografts and of autochthonous tumors in mouse models of human cancer in vivo. Furthermore, disassembly of the HMWR increases chromosome mis-segregation, which synergized with genotoxic agents to potentiate cancer cell vulnerability and improve therapeutic response. These findings suggest pharmacologic inhibition of HMWR as a novel anti-cancer strategy.

cancer biology↗

bioRxiv2025

Symbiosis through lysis: prophage activation underlies Lactiplantibacillus plantarum probiotic function

The release of bacterial bioactive molecules across the gut barrier is a crucial yet poorly understood step in microbe-host molecular dialog. Here we unravel a phage-driven mechanism that enables this process in a symbiont that supports host adaptive growth. In Lactiplantibacillus plantarum NC8 (LpNC8), we identify a stress-inducible prophage, pp2, that undergoes genotoxic-stress-dependent activation in vivo and triggers holin-lysin-mediated lysis. This controlled lytic program produces phage particles together with extracellular vesicles (EVs), enriched in symbiotic cues, including lipoteichoic acids. In a model of beneficial symbiosis, pp2-dependent lysis is strictly required for the ability of LpNC8to support juvenile growth in nutritionally challenged Drosophila melanogaster. Disruption of pp2-dependent lysis abolishes EVs release in vitro and alters the growth-promoting effect in vivo. We show that the acidic region of the Drosophila midgut, but not host antimicrobial peptides nor lysozymes, acts as a physiological trigger of prophage induction: removal of this acidic compartment markedly reduces phage production and impairs LpNC8-mediated growth promotion. These findings demonstrate that host gut physiology regulates prophage activation and reveal prophage-induced lysis as a previously unrecognized mechanism by which a beneficial gut bacterium releases symbiotic cues to support host development during nutritional stress.

microbiology↗

bioRxiv2025

Revealing the antibiotic resistome in the global hadal trenches by large-scale cultivation and metagenomics

The global hadal trenches that reside more than 6000 meters below the sea level, represent one of Earths most remote ecosystems, potentially harboring a microbial reservoir for antibiotic resistant bacteria (ARB) and antibiotic resistance genes (ARGs). However, the global hadal environments remain the least investigated ecosystem for ARB/ARG compositions and distribution. This study took three-fold approaches to investigate the ARB/ARGs in the global hadal trench sediments, i.e., large-scale cultivation to isolate and verify ARB/ARGs from Challenger Deep sediments, metagenomic analysis of sediment samples from Challenger Deep over a six-year period, and comparative study of resistomes across six hadal trenches through metagenomic analysis. The Challenger Deep sediments had a consistent average ARG abundance of 0.02 copy/cell over a six-year period, whereas some ARG subtypes fluctuated and showed distinct temporal dynamics. Large-scale screening of ARB via microbial cultivation using 13 classes of antibiotics led to enriching distinct ARB, for which eleven genera were identified by metagenomic sequencing as major host for ARGs. The global hadal trench sediments showed a variable ARG abundance, which was significantly lower than those from environments in proximity to human activities, representing a relatively pristine reservoir. Phylogenetic analysis suggested the hadal ARGs underwent niche-specific selections and formed hadal trench-specific clusters that diverged from human-associated lineages, which can be outward transported when disturbed. The study established the hadal trench sediments, as a relatively pristine reservoir of natural ARGs, providing a crucial environmental baseline for assessing their impacts on the ecosystems and public health risks.

microbiology↗