Biology subjects

Li, R.

Publications and source records attributed to Li, R..

At least 37 records · Page 2Linked to original sources

bioRxiv2026

A lifespan-scale single-cell atlas defines an early-childhood immunometabolic transition linked to age-referenced immune states

Childhood represents a critical period with rapid metabolic and immune remodeling, during which perturbations may have lasting consequences for health. We integrated single-cell RNA sequencing (scRNA-seq) profiles of peripheral blood mononuclear cells (PBMCs) from 2,008 healthy individuals aged 0-100 years. Age-resolved modeling highlighted an early-childhood transition centered at age 6, characterized by coordinated remodeling of metabolism-related transcriptional programs, particularly in monocyte and B-lineage cells. Matched serum metabolomics and lipidomics in a pediatric subcohort detected a temporally concordant wave of metabolite and lipid changes around ages 6-8 and extensive metabolite/lipid-transcript associations, prominently involving steroid and phospholipid species. Building on these findings, we developed an immunometabolic transition score and age-specific reference chart, which were evaluated in an independent healthy cohort and applied to quantify deviations in pediatric immune disorders. These findings highlight a coordinated immunometabolic transition in early childhood and provide an age-referenced framework for distinguishing atypical immune-state variation from healthy age-associated variation.

immunology↗

bioRxiv2026

Substrate recognition and ion coupling mechanism of the human VIAAT

Inhibitory neurotransmission, essential for neural circuit homeostasis and proper neurological function, depends on the efficient sequestration of {gamma}-aminobutyric acid (GABA) and glycine into synaptic vesicles. This critical process is mediated exclusively by the vesicular inhibitory amino acid transporter (VIAAT). Despite extensive biochemical and physiological investigation, the molecular mechanism governing VIAAT-mediated transport has remained incompletely understood. Here, we determined structures of human VIAAT in multiple functional states, including apo, GABA-bound, and glycine-bound states, as well as apo state in chloride-free condition. VIAAT adopts a classical LeuT-fold and we elucidated how its large, electronegative binding pocket accommodates both GABA and glycine. Moreover, we resolved two previously unidentified chloride-binding sites. Through integrative molecular dynamics simulations and functional mutagenesis, our results support roles for chloride and the conserved residue E213 in substrate binding and proton-coupled transport. Together, our findings establish a structural framework for VIAAT-mediated inhibitory neurotransmitter transport that illuminates the molecular basis of inhibitory synaptic transmission and provides a foundation for understanding VIAAT dysfunction in epilepsy and related neurodevelopmental disorders.

neuroscience↗

bioRxiv2026

Inverted logic of ecDNA localization converts nuclear periphery into oncogenic transcription hubs in cancer

Extrachromosomal DNA (ecDNA) is a major driver of cancer pathogenesis, however, its spatial organization in the nucleus is not currently understood. Here we show that ecDNAs, in contrast to chromosomal DNA, preferentially localize to the nuclear periphery yet resist peripheral gene silencing. Single-molecule multi-omic sequencing and imaging-based CRISPR screening demonstrate enhanced ecDNA hub formation, H3K27ac and H3K9me3 bivalency, late DNA replication, long-range CpG hypomethylation, and increased transcriptional output when ecDNAs localize to the nuclear periphery. EcDNA anchors to the nuclear lamina through H3K9me3-dependent interactions with the Lamin B Receptor (LBR), which if interrupted, results in inward migration of ecDNA particles, reduced ecDNA congregation, and decreased transcription of ecDNA-encoded genes. These results reveal inherent advantages of the spatial organization of ecDNA that are not available to chromosomal DNA, enhancing ecDNA congregation and amplifying oncogenic transcriptional output, by localizing to the nuclear periphery of cancer cells.

cancer biology↗

bioRxiv2026

A mycovirus identified from an outbreak fungal species complex reveals a parallel antiviral system

Mycoviruses are prevalent across major fungal lineages, yet none have been reported in the Cryptococcus gattii species complex (CGSC), the causative agent of the largest known fungal outbreak in immunocompetent hosts. Consequently, the occurrence of mycoviruses and the host determinants governing their infection in this important pathogenic clade remain unexplored. Through screening of 386 Cryptococcus isolates, we identified a mycovirus, designated CgTV1, in an environmental isolate of the Cryptococcus gattii species complex (CGSC). CgTV1 is a double-stranded RNA (dsRNA) mycovirus of the genus Totivirus, with a genome encoding a capsid protein and an RNA-dependent RNA polymerase. We showed that CgTV1 establishes a cryptic infection, because neither viral presence nor its clearance significantly alters host transcriptomic profiles, suggesting the existence of mechanisms that maintain virus-host homeostasis. Population genomic analyses reveal that an intact RNAi pathway constitutes a critical genetic barrier, and CgTV1 persistence strictly requires loss of function mutations in both AGO1 and AGO2. By pan-transcriptomics across 43 CGSC strains, we further uncovered an RNase III gene, CAI1, which exhibits high expression in the mycovirus positive isolate. Biochemical analysis indicates that Cai1 directly recognizes and degrades CgTV1 dsRNA, thereby constraining excessive mycoviral proliferation. We further demonstrate that Dicer and Cai1 act in parallel to maintain virus-host homeostasis: their combined ablation results in higher viral loads and more pronounced changes in host gene expression than ablation of either factor alone. Collectively, our findings provide the evidence of the occurrence of a mycovirus in the CGSC and reveal parallel mechanisms that enable cryptic mycoviral infections.

genetics↗

bioRxiv2026

Integrating complementary biological information for multi-objective enzyme engineering

Enzyme catalysts are increasingly used for sustainable pharmaceutical manufacturing, but engineering industrial biocatalysts remains challenging as multiple catalytic and developability properties must be optimized simultaneously from limited experimental data. Here, we develop a machine learning-guided multi-objective design framework that integrates sparse functional measurements with complementary evolutionary and structural information to engineer the ketoreductase Gre2. The resulting designs achieved simultaneous improvements in catalytic performance, protein yield, and thermal stability, with selected designs retaining improved performance under process-relevant conditions. More broadly, our results demonstrate that integrating complementary biological information enables efficient multi-objective enzyme engineering from sparse experimental data, providing a general strategy for accelerating industrial biocatalyst development.

bioengineering↗

bioRxiv2026

Unmasking genetic load: Genomic inbreeding drives growth depression in captive critically endangered Chinese Bahaba (Bahaba taipingensis)

Chinese bahaba (Bahaba taipingensis) is a critically endangered marine fish that has been commercially extinct in the wild. Conservation-oriented captive breeding has become an effective strategy for rescuing such endangered species, but concerns about inbreeding depression often remain. Here, after merely two generations of closed breeding from 18 wild founders, Chinese bahaba exhibited severe growth depression, with body length and weight diverging by more than three-fold. To further investigate the early genomic consequences of captive breeding, we analyzed whole-genome sequences from 348 F2 individuals together with 19 wild individuals from the same marine region. While genome-wide genetic diversity was overall preserved, closed breeding rapidly partitioned the F2 population into eight distinct genetic lineages. A significant elevation in genomic inbreeding was observed to facilitate the homozygous exposure of recessive deleterious mutations, which was strongly correlated with growth decline. An integrative framework combining GWAS, gene-level burden test, and ROH hotspots was applied to dissect the genetic architecture underlying growth decline, which converged predominantly on skeletal scaffolding and immune regulation. This was evidenced by candidate genes related to skeleton development and homeostasis (e.g. fam20b, c-fos, trpv5, and il23r), the GH/IGF axis (e.g. socs1a), and immune/inflammatory pathways (e.g. il23r, nlrp7, cd163, il12rb2), as well as calcium ion transport pathway. Together, our findings provide novel insights into the genomic consequences and genetic architecture of growth decline under captive conditions in Chinese bahaba, and offer critical guidance for genetic management in captive conservation programs of endangered species.

genetics↗

bioRxiv2026

From pelagic to reef: Genomic basis of morphological adaption during life-history transition in the orbicular batfish (Platax orbicularis)

Metamorphosis enables teleosts to transition between ecological niches, driving lineage-specific morphological innovations. The orbicular batfish (Platax orbicularis) exemplifies this, transforming from a pelagic larva into a reef-associated juvenile with extreme allometric fin elongation. Here, we generated a chromosome-level genome assembly of 715.46 Mb, with 99.4% completeness. Integrating comparative genomics with tissue-specific transcriptomics, we demonstrate that such transformation is a systemic process shaped by both long-term evolutionary adaptation and short-term developmental reprogramming. Comparative analyses revealed expansion of development-related gene families and significant evolution of immune- and sensory-related families, likely associated with ecological niche transition. Spatiotemporal clustering of metamorphosing fin transcriptomes identified rapid cell cycle activation accompanied by sustained suppression of basal metabolism, indicating developmental trade-offs during fin elongation. Several differentially expressed genes involved in cell cycle (ankfn1 and mcph1), ossification (cyp24a1 and sema4d), and extracellular matrix remodeling (sdc4 and serpine1) exhibited positive selection, suggesting coordinated regulatory and protein-level adaptation. Among an extensive repertoire of 49 hox genes, four (hoxb6b, hoxc8a, hoxd9b, hoxd10a) were differentially expressed, implicating developmental regulators in fin remodeling. Together, our findings offer new insights into the evolutionary context and molecular mechanisms of metamorphosis in orbicular batfish, and advance the understanding of adaptive evolution and metamorphosis innovations in teleosts.

genomics↗

bioRxiv2026

A pan-genomic and methylomic analysis reveals a distinct signature in Vibrio alginolyticus isolated from wild fish

Vibrio alginolyticus is a ubiquitous opportunistic pathogen in estuarine and marine ecosystems and a leading cause of vibriosis in humans and aquatic animals. Yet genomic and epigenomic landscapes of V. alginolyticus from wild fish remain poorly defined. Here, we present a pan-genomic and methylomic framework based on 89 high-quality V. alginolyticus genomes, including 46 newly sequenced isolates recovered from 105 wild marine fish representing 17 species in Hong Kong waters of the South China Sea, plus all publicly available complete genomes. We reported a 32.38% prevalence of V. alginolyticus in wild fish. Phylogenomic analysis resolved four distinct clades, with Clade IV dominated by wild-fish isolates and characterized by low virulence and low antimicrobial resistance. Pan-genomic analysis revealed a closed pan-genome with a substantially depleted accessory genome in Clade IV. We identified a total of 763 antimicrobial resistance (AMR) genes from 89 strains, which covered 32 gene types and spanned four resistance mechanisms, with efflux pumps as the most prevalent strategy. Critically, resistance genes were almost exclusively chromosomal rather than plasmid-borne. Virulence profiling confirmed the presence of tlh and T6SS genes but the absence of the high-risk human pathogenic factors tdh and ctxB. Methylomic analysis using nanopore sequencing uncovered 355 DNA methyltransferases and 140 strain-specific methylation motifs with dominance by 6mA. Notably, 71.90% of methyltransferases resided in the accessory genome and were disseminated by mobile genetic elements, especially plasmids. Motif combinations were highly strain-specific and largely decoupled from phylogeny, except for a shared motif signature defining Clade IV. The GATC motif was essential across all V. alginolyticus strains and showed significant enrichment in virulence gene regions but not in AMR gene loci, revealing differentiated epigenetic modification characteristics. This study nearly doubled the number of high-quality complete genomes available for V. alginolyticus and provides the first comprehensive methylomic characterization for this species. Our findings reveal a phylogenetically distinct, low-virulence, low-resistance V. alginolyticus clade widely shared among wild fish, with important implications for One Health surveillance and evolutionary adaptation of marine pathogens.

genomics↗

bioRxiv2026

Pavlovian conditioned approach with different reward magnitudes reveals opposing effects of acute and chronic semaglutide treatment

Rationale: Glucagon-like peptide-1 receptor agonists (GLP-1RAs) have attracted interest for their effects on motivational processes beyond satiation and weight loss, including motivation for drug rewards. Reward-predictive cues can acquire motivational value and promote food- and drug-seeking, raising the possibility that GLP-1RAs affect intake by altering cue-motivated behavior. Preclinical studies report reduced food intake and responding for drug rewards following GLP-1RA treatment. However, many preclinical studies have used acute treatment; whereas, clinically, GLP1-RAs are administered as chronic treatments with dose escalation to mitigate adverse effects. Objectives: Using a modified Pavlovian conditioned approach (PavCA) paradigm, we directly compared the effects of acute and chronic semaglutide treatment on conditioned approach behavior elicited by cues predicting different magnitudes of palatable food reward in male and female rats. Results: Although both treatment regimens reduced body weight relative to vehicle treatment, chronic semaglutide increased, whereas acute semaglutide decreased, sign-tracking toward reward-associated cues. Rats exhibited greater sign-tracking toward cues predicting large versus small rewards, but semaglutide did not differentially alter this reward-magnitude effect. Acutely treated rats consumed fewer reward pellets and exhibited less food-cup activity during non-cue periods. These findings suggest that nonspecific behavioral suppression or malaise may have contributed to reduced responding after acute treatment. Conclusions: The effects of semaglutide on cue-motivated behavior depend on the treatment regimen. Acute-treatment studies should be interpreted cautiously because adverse or nonspecific effects may contribute to apparent reductions in motivation.

neuroscience↗

bioRxiv2026

M.FcoHsdM-dependent DNA methylation coordinates secretion-associated gene expression, interbacterial competition, and virulence in Flavobacterium columnare

Flavobacterium columnare causes columnaris disease in freshwater fish, but the contribution of DNA methylation to its physiology and pathogenicity remains poorly understood. Here, we characterized M. FcoHsdM, a type I restriction-modification methyltransferase previously identified by nanopore methylome analysis. Deletion of the gene encoding M. FcoHsdM abolished methylation at its associated recognition motifs without affecting planktonic growth. The mutant exhibited impaired biofilm formation, gliding motility, colony spreading, and gelatinolytic activity, together with increased outer-membrane vesicle production and complete attenuation in a zebrafish infection model. Transcriptomic and extracellular proteomic analyses revealed broad changes in secretion and cell surface associated functions. In particular, genes encoding components of a putative type VI secretion system were coordinately downregulated, and the mutant showed reduced antagonistic activity against Aeromonas hydrophila. Several predicted type IX secretion system substrates and extracellular enzymes were also reduced, potentially contributing to the motility and virulence defects. Two such motifs were identified in tssP, which encodes a predicted Bacteroidota-specific type VI secretion system membrane-complex component. One motif overlapped a computationally predicted binding site for the leucine-responsive regulatory protein Lrp, raising the hypothesis that intragenic methylation may influence regulator occupancy at the tssP locus. Collectively, these findings identify M.FcoHsdM-dependent methylation as an important contributor to secretion-associated gene expression, interbacterial antagonism, and virulence in F. columnare.

microbiology↗

bioRxiv2026

Genetic regulation of circulating metabolome in cattle

The circulating metabolome is a vital intermediate layer linking genetics to complex phenotypes, yet existing genome-wide studies-even in humans-rarely capture dynamic physiological contexts or cellular regulatory mechanisms. Here, we present the Cattle Metabolome Atlas (https://cattlema.farmgtex.org/), a comprehensive resource of 3,436 plasma metabolites and 4,851 serum metabolites from 4,651 animals with matched sequence-level genotypes across highly dynamic parity and lactation stages. We mapped 728 plasma and 622 serum metabolite quantitative trait loci (mQTL), revealing widespread context-dependent regulatory architectures. Integrating these mQTL with the multi-tissue expression quantitative trait loci (eQTL) and single-cell atlas of 59 tissues demonstrates that 74-79% of mQTL colocalize with eQTL across 29 tissues, prioritizing the liver as the primary systemic hub and resolving metabolic programs at single-cell resolution. Furthermore, we charted 538 causal gene-tissue-metabolite-trait cascades across 11 complex traits in cattle. Finally, cross-species analyses demonstrate partial evolutionary conservation of genetic metabolism between cattle and humans, establishing this atlas as a powerful asset for cattle genetics and genomics, selective breeding, and comparative biology.

genetics↗

bioRxiv2026

A Distal Super-Enhancer Regulate CD47 Expression and Promotes Macrophage-Mediated Phagocytosis of Ovarian Cancer Cells

CD47 is an innate immune checkpoint that can protect tumor cells from macrophage-mediated clearance, but the regulatory mechanisms underlying its expression in ovarian cancer (OC) remain incompletely understood. Here, we investigated the epigenetic regulation of CD47 expression in OC. Single-cell and spatial transcriptomic analyses indicated preferential CD47 expression in malignant epithelial cells. Integration of publicly available epigenomic datasets revealed a distal regulatory region with enhancer-associated features across ovarian cancer models and HGSOC patient samples. A genome-wide CRISPR-Cas9 screen further implicated PITX2 and EP300 as regulators of CD47 expression. Chromatin immunoprecipitation assays showed PITX2 and EP300 occupancy at candidate enhancer elements within this CD47 regulatory region. Comparative epigenomic analyses suggested that features of this regulatory landscape are also present in fallopian tube epithelial cells and become more prominent in OC. Together, these findings support a PITX2-EP300 regulatory axis associated with CD47 expression and provide evidence for its potential contribution to tumor immune evasion.

cancer biology↗

bioRxiv2026

Cysteine reduction rather than methionine restriction promotes immunometabolic fitness to confer survival benefit in aging

Elevated sulfur-containing amino acids (SAA; methionine and cystine) are linked to human mortality. While methionine restriction (MR) extends lifespan in animals, it is often ignored that traditional longevity-promoting MR diets also lack cystine. When dietary cystine is eliminated, host redirects substrates from methionine cycle and generates cysteine via cystathionine {gamma}-lyase (CTH) in transsulfuration pathway, leaving it unclear which SAA controls aging. Here, we show that selective cysteine restriction in Caenorhabditis elegans enhanced lifespan and stress survival independently of methionine. Notably, cysteine-free diets (methionine-replete or restricted) in Cth-deficient mice induced pro-metabolic effects, whereas MR with normal cysteine was ineffective. Sustained 70% cysteine reduction in aged Cth-/- mice reprogrammed the immunometabolic axis, conferring healthspan benefits. Thus, lowering cysteine while keeping the methionine pool intact enhances healthy lifespan.

physiology↗

bioRxiv2026

Pathogenic T-bet+ memory B cells worsen multiple sclerosis through myeloid cell activation

Depletion of B cells in multiple sclerosis (MS) is beneficial yet there is no defined pathogenic B cell subset in MS. Here, we demonstrate that T-bet+ memory B cells are rare in control human brain specimens but are found in MS lesions. Transfer of murine T-bet+ memory B cells into mice with ongoing experimental autoimmune encephalomyelitis (EAE), a model of MS, worsened their disability and demyelination. Microglia/macrophage density increased in central nervous system parenchyma even though B cells mostly remained in barriers. In culture, secreted factors from T-bet+ memory B cells promoted macrophage migration. IFN-{gamma} produced by T-bet+ memory B cells activated microglia to secrete chemokines that further enabled macrophage migration. Consistent with their age-associated elevation, conditional deletion of T-bet in B cells lowered EAE severity in aged but not young mice. We define T-bet+ memory B cells as pathogenic in EAE and MS through their IFN-{gamma}-facilitated interactions with microglia/macrophages.

immunology↗

bioRxiv2026

A Hymenoptera-restricted gene mediating ant castes co-opts deeply conserved machinery to control organ size

Lineage-specific genes are widespread and have been implicated as phenotypic innovation inducers, but how they acquire complex developmental functions remains poorly understood. Ant queens and workers develop dramatically different organ sizes from identical genomes under juvenile hormone (JH) control, yet the molecular effectors translating JH signalling into caste-specific organ growth remain unknown. Here we identify torch, a Hymenoptera-restricted gene, as the most consistently gyne-biased and JH-responsive gene across 68 ant species. Knockdown of torch in virgin queens of Monomorium pharaonis produces a worker-like, multi-organ growth-restricted phenotype. Mechanistically, torch harbours an E-box-like motif activated by the JH receptor Gce-Tai and acts as a GA-repeat-binding transcription factor that regulates Hippo signalling, the deeply conserved organ-size control pathway in animals. Expressing torch heterologously in mice and a growth-restricted Drosophila background shows that the gene retained its general growth-promoting activity across more than 700 million years of animal evolution in lineages that lack the gene, establishing that its function is mediated through conserved rather than ant-specific machinery. A lineage-specific gene can therefore acquire complex morphogenetic function by co-opting ancient organ-size circuitry, providing a general route by which novel genes can drive phenotypic innovation.

evolutionary biology↗

bioRxiv2026

Orthoflaviviruses use diverse binding modes to engage LDLR family receptors

Orthoflaviviruses are major human pathogens that cause substantial morbidity and mortality worldwide. The viral envelope (E) mediates entry of orthoflaviviruses into host cells by interacting with cellular receptors, including members of the low-density lipoprotein receptor (LDLR) family. Here, we determined cryo-electron microscopy (cryo-EM) structures of yellow fever virus (YFV) E bound to low-density lipoprotein receptor-related protein 4 (LRP4) and LRP8, and of tick-borne encephalitis virus (TBEV) E bound to LRP8. Structural and functional studies reveal that YFV engages two low-density lipoprotein receptor class A (LA) repeats of LRP4 and LRP8 primarily through domain III (DIII) and the DI-DIII linker of its E protein, with each LA repeat making distinct contacts. In contrast, TBEV relies on a distinct surface on domain II (DII) of its E protein to interact with LRP8. Despite these differences, both viruses require engagement of two sequential receptor LA repeats for binding. Our findings identify key determinants of receptor specificity for these two orthoflaviviruses, with implications for vaccine development and therapeutic antibody targeting.

microbiology↗

bioRxiv2026

Human panepigenome represents epigenomic diversity

The human pangenome captures genetic diversity beyond a single linear reference, yet conventional DNA methylome maps largely assume that the underlying CpG substrate is fixed. Here we present a first draft of the human panepigenome on DNA methylation, generated from 440 haplotype-resolved long-read methylomes spanning 26 globally distributed populations. This map jointly captures CpG presence, absence and methylation across diverse human haplotypes, revealing 12.8 million CpGs absent from GRCh38 and an average of 1.2 million variant-associated CpGs (var-CpGs) per methylome. Var-CpGs captured population-associated epigenomic variation beyond that represented by shared reference CpGs, and structural variants could create or remove entire CpG islands, frequently through mobile element insertions. Promoter var-CpG methylation was associated with transcript expression, with most associations persisting after adjustment for the underlying CpG-altering variant, whereas a subset showed evidence of mediation or variant-by-methylation interactions. CpG-altering variants were also enriched among molecular QTLs in HPRC2 and across GTEx tissues, and among clinically and pharmacogenomically annotated loci. Together, these results establish a haplotype-resolved framework in which human epigenomic diversity reflects not only variation in methylation level but also genetic variation in presence or absence of CpG substrates, providing a foundation for panepigenomic studies across tissues, populations and disease contexts.

genomics↗

bioRxiv2026

Genomic variation associated with endosymbiont shuffling and areal growth in the endangered elkhorn coral, Acropora palmata

Biodiversity losses continue to outpace traditional management, underscoring the need to understand adaptive capacity and the potential for interventions to increase fitness under climate change. We undertook a genome-wide association study on 156 Acropora palmata genets to investigate the genomic basis of areal growth, endosymbiont association, and thermal tolerance. Seven peaks on chromosomes 1, 3 and 14 were associated with endosymbiont shuffling and two peaks on chromosome 4 were associated with areal growth. As variants were located in non-coding regions we incorporated additional data from an independent field-transplant experiment to investigate their relationship with patterns of gene expression. Intersection of these datasets implicated melanocortin-like receptor activity and Ran GTPase activating protein 1 in endosymbiont composition and surface area growth, respectively. Results indicate that growth and endosymbiont associations may represent more viable intervention targets than temperature tolerance and highlight the need to better understand the role of non-coding variation in basic biology and development of restoration interventions.

genomics↗