Biology subjects

Zhang, P.

Publications and source records attributed to Zhang, P..

At least 109 records · Page 6Linked to original sources

bioRxiv2025

High-fat circulating nutrients promote growth and invasion in a 3D microfluidic tumor model of triple-negative breast cancer

Diet influences the levels of small molecules that circulate in plasma and interstitial fluid, altering the biochemical composition of the tumor microenvironment (TME). These circulating nutrients have been associated with how tumors grow and respond to treatment, but it remains difficult to parse their direct effects on cancer cells. Here, we combine a three-dimensional (3D) microfluidic tumor model with physiologically relevant culture media to investigate how concentrations of circulating nutrients influence tumor growth, cancer cell invasion, and overall tumor metabolism. Human triple-negative breast cancer cells cultured in 2D under media conditions mimicking five different dietary states show no observable differences in proliferation or morphology. Nonetheless, those exposed to high-fat conditions exhibit increased metabolic activity and upregulate genes associated with motility and extracellular matrix remodeling. In the 3D microfluidic model, high-fat conditions accelerate tumor growth and invasion and induce the formation of hollow cavities. Surprisingly, the presence of these cavities does not correlate with an increase in apoptosis or ferroptosis. Instead, RNA-sequencing analysis revealed that high-fat conditions induce the expression of MMP1, consistent with cavitation via cell invasion. Mimicking the flow of circulating nutrients within the TME can thus be used to identify novel connections between metabolic states and tumor phenotype.

bioengineering↗

bioRxiv2025

Population-level structural variant characterization from pangenome graph

Population-level structural variant (SV) profiling is crucial in the era of pangenomes. However, identifying SVs from genome assemblies and pangenome graphs remains a significant challenge. Here we present Swave, a sequence-to-image, deep-learning based method that accurately resolves both simple and complex SVs, along with their population characteristics, from assembly-derived pangenome graphs. Swave introduces projection waves to summarize the dotplot images that capture mapping patterns between reference and SV-indicating alleles in pangenome. These images are analyzed by a recurrent neural network to distinguishes true SV signals from background noise introduced by genomic repeats. Swave demonstrates superior performance in both SV type classification and genotyping compared to existing methods. When applied to a healthy cohort (n=334) and a rare-disease cohort (n=574), Swave reveals complex and polymorphic SV patterns across human populations and identifies potentially pathogenic SVs. These advancements will facilitate the creation of comprehensive population-level SV catalogs, deepening our understanding of SVs in genetic diversity and disease associations.

bioinformatics↗

bioRxiv2025

A single cell multi-omic analysis identifies molecular and gene-regulatory mechanisms dysregulated in the developing Down syndrome neocortex

Down syndrome is the most common genetic cause of intellectual disability, presenting with cognitive, learning, memory, and language deficits. The cellular and molecular mechanisms driving this disorder remain unclear, limited by a lack of systematic studies in the developing human brain. Here, we leveraged single-nucleus multi-omics to profile the mid-gestation neocortex in a cohort of 26 donors. We observed a reduction in neural progenitors and corticothalamic neurons and concomitant increase of intratelencephalic neurons, accompanied by accelerated time to neuronal specification. We uncovered widespread changes in gene expression, chromatin accessibility and cell interaction networks impacting neurogenesis, specification and maturation and gene-regulatory networks directing these processes, including those downstream of transcription factors encoded in chromosome 21. Finally, we identified cell-specific molecular pathways shared with other neurodevelopmental disorders as well as heritability enrichment of GWAS signals in altered chromatin. Together, our data revealed a cascade of molecular dysregulation outlining the earliest steps in Down syndrome, providing a foundation for future therapeutic targets.

genomics↗

bioRxiv2025

Mitochondrial Genome Variants and Nuclear Mitochondrial DNA Segments in 7331 Individuals from NyuWa and 1KGP

Dysfunctional mitochondria are implicated in various diseases, while little is known about comprehensive characterization of mitochondrial DNA (mtDNA) in Chinese population. Here, we conducted a systematic analysis of mtDNA from 7331 samples, comprising 4129 Chinese samples (NyuWa) and 3202 samples from the 1000 Genomes Project (1KGP). We identified 7216 distinct high-quality mtDNA variants and classified them into 22 macrohaplogroups, and detected 1466 distinct nuclear mitochondrial DNA segments (NUMTs), with 88 mtDNA variants and 642 NUMTs being specific to NyuWa. The genome-wide association analyses revealed that 12 mtDNA variants were significantly correlated with 199 nuclear DNA variants. Our findings revealed that all individuals in both NyuWa and 1KGP harbored common NUMTs, and one-fifth possessed ultra-rare NUMTs, which tended to insert into nuclear gene regions. Compared to 1KGP, significant enrichment of nuclear breakpoints in long interspersed nuclear elements (LINEs) was observed for rare NUMTs in NyuWa. Overall, this study represents the first comprehensive profiling the landscape of Chinese NUMTs and offers the most extensive resource of Chinese mtDNA variants and NUMTs based on high-depth WGS to date, providing valuable reference resources for genetic research on mtDNA-related diseases.

genomics↗

bioRxiv2025

Host-specific adaptation and fitness trade-off of Barley Yellow Dwarf Viruses suggested by experimental evolution through aphid inoculation on multiple Poaceae species

Yellow dwarf viruses are damaging viruses infecting cereals. They are able to infect a wide range of host plants belonging to the Poaceae family. The ban of neonicotinoids in Europe has resulted in an increasing disease incidence and triggered the need to better understand their emergence and spread. The ability of a Barley yellow dwarf virus (BYDV) population to adapt to different hosts has never been studied. We performed an experimental evolution of two BYDV species (BYDV-PAS and BYDV-PAV) to study their adaptation to four Poaceae species (wheat, oat, two-row barley, and six-row barley). After four months of evolution (4 passages from plant to plant), the replicative fitness of the final viral populations was estimated, and the complete viral genomes were sequenced by high-throughput sequencing in pools of BYDV populations. Wildly divergent evolutionary trajectories were obtained, with stable or increased fitness, up to extinctions of viral populations within and among plant species. To understand these results, the composition of viral populations was analysed in detail using single nucleotide polymorphism (SNP) calling, clustering, and haplotype reconstruction methods. Interestingly, adaptation to oat and barley was mainly explained by a combination of BYDV-PAV haplotypes showing specific mutations. In contrast, adaptation to wheat was mainly explained by a combination of BYDV-PAS haplotypes harbouring specific mutations. Moreover, these local adaptations were associated to an adaptation cost in other hosts for some viral populations. The presence of adaptation costs in controlled but realistic conditions opens the door for evaluating practices such as crop mixtures or rotations on fields, as a means to mitigate the impact of BYDV. Author summaryThe use of genetically uniform plant resistant varieties in traditional agriculture creates unique environments that facilitate the rapid emergence of highly virulent pathogen populations. In natural ecosystems, host spatial and temporal heterogeneity help limit the outbreak of epidemics. As a result, disease management strategies such as crop mixtures and rotations have been proposed to reduce the selection pressure exerted on pathogen populations and prevent the emergence of "super-infectious" pathogens. These strategies would be particularly relevant against Barley yellow dwarf virus (BYDV), the virus causing the greatest economic losses on cereals, as insecticides controlling the disease are banned in Europe and few resistance genes are currently available. However, the effectiveness of these strategies against BYDV remains to be demonstrated. By experimentally evolving a natural BYDV population on different cereal species through natural transmission (e.g. vector instead of mechanical inoculation), we showed that different combinations of mutations and haplotypes enable the virus to adapt to different cereal species. Moreover, for some viral populations, the combination promoting adaptation to one host resulted in maladaptation in another host. These host-specific adaptations are key elements in the establishment of crop mixtures and rotations in the field. Our results generated in controlled but realistic conditions demonstrate for the first time that these cultural practices could be effective against these viruses.

evolutionary biology↗

bioRxiv2025

The bifunctional dynamin-like GTPase switch DynAB modulates both vegetative and sporulation cell division in Streptomyces.

As part of their complex developmental lifecycle, the multicellular filamentous bacteria Streptomyces have evolved two modes of cell division distinct from binary fission. In vegetative cell division, irregularly spaced cross-walls form within vegetative hyphae, whereas in sporogenic hyphae, regularly spaced sporulation septa form synchronously, leading to spore formation. However, the mechanisms controlling these processes largely remain unknown. The bacterial dynamin-like protein pair DynAB was previously reported to be a component of sporulation septa. Here, we reveal that DynA and DynB have critical roles in both cell division modes, regulating the formation of sporulation septa and cross-walls, with the Streptomyces cell division protein SsgB modulating their activities. dynAB deletion and overexpression, respectively, increased and abrogated cross-wall formation in vegetative hyphae, and Streptomyces DynAB also inhibited cell division in Escherichia coli, resulting in formation of unicellular filamentous cells and suggesting an ancient and conserved function for these proteins. Notably, SsgB could relieve the inhibition of cell division by DynAB in both Streptomyces and E. coli. In contrast to DynAB, SsgB overexpression generated spore-like compartments in vegetative hyphae, a phenomenon that required disruption of the DynAB complex. Fluorescent tags revealed dynamic localization of DynAB during development, and further analyses indicated that, in sporogenic hyphae, the timing of DynAB expression, their GTP-binding activity, and interaction with SsgB were associated with the synchronous initiation of sporulation septation. Our findings establish DynAB as an integrator of spatiotemporal cues in bacterial multicellularity and provide insights into the evolution of complex cell cycle regulation in prokaryotes. SignificanceThe evolution of multicellularity in bacteria involved the development of complex mechanisms to spatially and temporally coordinate cell division. Streptomyces, renowned for their production of bioactive secondary metabolites, exemplify bacterial complexity. This study reveals how Streptomyces employ the dynamin-like proteins DynAB as a bifunctional molecular switch, enabling transition between vegetative and reproductive growth through integrated interactions with developmentally regulated proteins and the availability of the energy supplier GTP. Importantly, DynAB could repress cell division in both Streptomyces and Escherichia coli, suggesting an evolutionary origin of these proteins prior to bacterial multicellularity. Our work reveals the dual function and switch mechanism of DynAB in Streptomyces, providing insights into the emergence of dynamic cell cycle control in prokaryotes.

microbiology↗

bioRxiv2025

Development of a replication-defective MPXV platform for fundamental and therapeutic research

The recent global outbreaks of mpox highlight the urgent need for both fundamental research and antiviral development. However, studying monkeypox virus (MPXV), with its large and complex genome, remains challenging due to the requirement for high-containment facilities. Here, we describe a novel strategy for de novo assembly of MPXV clade IIb genomes in bacterial artificial chromosomes using transformation-associated recombination cloning. Leveraging CRISPR-Cas9 and Lambda Red recombination, we engineered replication-defective MPXV particles with dual deletions of OPG96 (M2R) and OPG158 (A32.5L)--genes essential for virion assembly, that are capable of recapitulating key stages of the viral life cycle. Our work demonstrates the utility of replication-defective MPXV particles as a reliable platform for high-throughput antiviral discovery, offering significant advantages for both fundamental virology studies and therapeutic development against orthopoxviruses.

microbiology↗

bioRxiv2025

Population-specific brain charts reveal Chinese-Western differences in neurodevelopmental trajectories

Human brain charts provide unprecedented opportunities for decoding neurodevelopmental milestones and establishing clinical benchmarks for precision brain medicine 1-7. However, current lifespan brain charts are primarily derived from European and North American cohorts, with Asian populations severely underrepresented. Here, we present the first population-specific brain charts for China, developed through the Chinese Lifespan Brain Mapping Consortium (Phase I) using neuroimaging data from 43,037 participants (aged 0-100 years) across 384 sites nationwide. We establish the lifespan normative trajectories for 296 structural brain phenotypes, encompassing global, subcortical, and cortical measures. Cross-population comparisons with Western brain charts (based on data from 56,339 participants aged 0-100 years) reveal distinct neurodevelopmental patterns in the Chinese population, including prolonged cortical and subcortical maturation, accelerated cerebellar growth, and earlier development of sensorimotor regions relative to paralimbic regions. Crucially, these Chinese-specific charts outperform Western-derived models in predicting healthy brain phenotypes and detecting pathological deviations in Chinese clinical cohorts. These findings highlight the urgent need for diverse, population-representative brain charts to advance equitable precision neuroscience and improve clinical validity across populations.

neuroscience↗

bioRxiv2025

RNA structural complexity dictates its ion atmosphere

Electrostatic interactions mediated by the surrounding ions govern virtually every facet of RNA behavior. Most studies have focused on rigid, well-folded motifs, leaving the structurally heteregeneous, and biologically ubiquitous, flexible RNAs underexplored. To address this gap, we performed molecular dynamics simulation of three RNAs spanning the structural continuum: an unstructured poly-uridylic tract (rU30), a semiflexible cytosine-adenine-guanine (CAG) repeat, and the tightly folded Beet Western Yellow Virus (BWYV) pseudoknot. Despite carrying nearly identical net charge, their ion atmospheres diverge strikingly. rU30 envelops itself in a diffuse Mg2+ environment retained through two or more hydration shells, whereas the CAG repeat and pseudoknot favor more localized outer-sphere Mg2+ binding. In contrast, Ca2+ tends to form inner-sphere contacts with all three RNAs, regardless of their folds. Remarkably, the diffuse ion clouds around unstructured RNAs extend farther into solution than that of the folded RNAs, significantly broadening their electrostatic sphere of influence. Nonetheless, the ion exchange kinetics remain virtually unchanged, demonstrating a surprising decoupling between spatial distribution and dynamical turnover. Our findings reveal RNA structural flexibility as a powerful lever for tuning ionic screening, with important implications for biomolecular recognition, RNA-driven phase separation, and physical properties of RNA-rich condensate. TOC Graphic O_FIG O_LINKSMALLFIG WIDTH=200 HEIGHT=149 SRC="FIGDIR/small/654961v1_ufig1.gif" ALT="Figure 1"> View larger version (29K): org.highwire.dtl.DTLVardef@12e78aborg.highwire.dtl.DTLVardef@1f4328borg.highwire.dtl.DTLVardef@122561dorg.highwire.dtl.DTLVardef@143c5ff_HPS_FORMAT_FIGEXP M_FIG C_FIG

biophysics↗

bioRxiv2025

Deep learning guided discovery of antibacterial polymeric nanoparticles

Drug-resistant bacterial infections pose a serious threat to global health, driving the development of novel antibacterial strategies beyond classic antibiotics. Self-assembled polymeric nanoparticles (SANPs) have emerged as promising candidates due to their unique structural properties, which enhance membrane interaction, drug loading, and therapeutic accumulation. The structural diversity and tunable properties of SANPs provide a flexible design platform for antibacterial applications. However, navigating the vast chemical space of SANPs remains a significant challenge due to the complex structure-activity relationships. To address this, we developed PolyCLOVER, a deep learning-guided framework for the efficient discovery of antibacterial SANPs. The framework integrates multi-stage self-supervised learning, active learning, and high-throughput experimentation to iteratively guide the discovery of SANPs with potent antibacterial activity and low toxicity. Through this framework, we identified three potent SANPs within a combinatorial library of [~]100,000 poly({beta}-amino ester)s, with minimum inhibitory concentrations of 4 g/mL and 8 g/mL against clinically multidrug-resistant S. aureus and A. baumannii, respectively. Moreover, they can also act as antibiotic carriers, restoring the sensitivity of pathogens to penicillin G. In vivo studies demonstrated their therapeutic efficacy both as monotherapies and in combination therapies with antibiotics. These results demonstrate PolyCLOVER as a powerful framework for discovering multi-functional SANPs to combat antibiotic resistance.

microbiology↗

bioRxiv2025

White matter microstructure and macrostructure brain charts across the human lifespan

Normative reference charts are widely used in healthcare, especially for assessing the development of individuals by benchmarking anatomic and physiological features against population trajectories across the lifespan. Recent work has extended this concept to gray matter morphology in the brain, but no such reference framework currently exists for white matter (WM) even though WM constitutes the essential substrate for neuronal communication and large-scale network integration. Here, we present the first comprehensive WM brain charts, which describe how microstructural and macrostructural features of WM evolve across the lifespan, by leveraging over 35,120 diffusion MRI scans from 50 harmonized studies. Using generalized additive models for location, scale, and shape (GAMLSS), we estimate age- and sex-stratified trajectories for 72 individual white matter pathways, quantifying both tract-specific microstructural and morphometric features. We demonstrate that these WM brain charts enable four important applications: (1) defining normative trajectories of WM maturation and decline across distinct pathways, (2) identifying previously uncharacterized developmental milestones and spatial gradients of tract maturation, (3) detecting individualized deviations from normative patterns with clinical relevance across multiple neurological disorders, and (4) facilitating standardized, cross-study centile scoring of new datasets. By establishing a unified, interpretable reference framework for WM structure, these brain charts provide a foundational metric for research and clinical neuroscience. The accompanying open-access trajectories, centile scoring tools, and harmonization methods facilitate precise mapping of WM development, aging, and pathology across diverse populations. We release the brain charts and provide an out-of-sample alignment process as a Docker image: https://zenodo.org/records/17561821.

neuroscience↗

bioRxiv2025

Design of an orally bioavailable small molecule that modulates the microtubule-associated protein tau's pre-mRNA splicing

Frontotemporal dementia with parkinsonism linked to chromosome 17 (FTDP-17) is caused by the aberrant alternative pre-mRNA splicing of microtubule-associated protein tau (MAPT) exon 10, the inclusion of which encodes for a toxic tau protein harboring four microtube domains (4R tau). Here, we describe the design of an RNA-targeted small molecule that thermodynamically stabilizes the structure of a pre-mRNA splicing regulator element in the MAPT pre-mRNA exon 10-intron junction to reduce the inclusion of exon 10 and hence 4R tau abundance. Structure-based drug design was used to obtain compounds that form a network of specific interactions to the RNA including multiple interactions between a one nucleotide A-bulge and the Hoogsteen face of a closing GC base pair, the latter of which was enabled by the design of base triple interactions. A battery of assays revealed that the compound binds the target in vitro and in cells and affects pre-mRNA splicing in various cellular models including primary neurons from a human tau (htau) knock-in mouse model. The orally bioavailable compound was administered per os (p.o.), where treatment diminished exon 10 inclusion, and reduced the 4R tau protein isoform. Further, the molecule mitigated cellular pathologies and behavioral phenotypes observed in the htau transgenic mouse model. This study provides a potentially general pipeline to design compounds that target RNAs and affect disease pathways and deliver compounds that have oral bioavailability and blood-brain barrier penetrance.

biochemistry↗

bioRxiv2025

Microglial Fructose Metabolism Is Essential for Glioblastoma Growth

Glioblastoma (GBM) is most common and aggressive primary brain tumor in adults, for which standard of care hasnt changed in twenty years. GBM tumor associated macrophages (TAMCs), consisting of infiltrating myeloid cells from the periphery and resident microglia cells, are pro-tumorigenic, promoting tumor growth. Fructose is one of the most abundant metabolites in the GBM tumor microenvironment (TME), as well as in the healthy central nervous system (CNS). In the CNS and GBM, microglia are the predominant expressors of the fructose transporter GLUT5. Mice lacking the GLUT5 transporter (GLUT5-KO) survive significantly longer after orthotopic implantation of two glioma cell lines than wildtype mice, which is not due to dietary fructose or peripherally derived TAMCs. Investigation of the TME showed that GLUT5-KO mice have more highly activated and inflammatory innate and adaptive immune compartments. Microglia cultured in fructose have a decreased phagocytic ability and exhibit decreased inflammatory capacity due to the polyol pathway promoting redox homeostasis.

cancer biology↗

bioRxiv2025

Evolution of T cell responses in the tuberculin skin test reveals generalisable Mtb-reactive T cell metaclones.

T cells contribute to immune protection and pathogenesis in tuberculosis, but measurements of polyclonal responses have failed to resolve correlates of outcome. We report the first temporal evaluation of the human in vivo clonal repertoire of Mtb-reactive T cell responses, by T cell receptor (TCR) sequencing at the site of a standardised antigenic challenge. Initial recruitment of non-Mtb reactive T cells is followed by enrichment of Mtb-reactive clones arising from oligoclonal T cell proliferation. We introduce a modular computational pipeline, Metaclonotypist, to sensitively cluster distinct TCRs with shared epitope specificity, which we apply here to establish a catalogue of public Mtb-reactive HLA-restricted T cell metaclones. Although most in vivo Mtb-reactive T cells are private, 10 metaclones were sufficient to identify Mtb-T cell reactivity across our study population (N[≥]128), indicating striking population level immunodominance of specific TCR-peptide interactions that may offer novel approaches to patient stratification and vaccine development.

immunology↗

bioRxiv2025

V1 superficial layers create a saliency map that feeds forward to the parietal cortex for attentional guidance

A salient visual object with a distinct feature from the surrounding environment automatically captures attention. While the saliency signals have been found in many brain regions, their source remains highly controversial. Here, we investigated the neural origin of visual saliency using cortical layer-dependent functional magnetic resonance imaging (fMRI) of cerebral blood volume (CBV) at 7 Tesla. Behaviorally, human observers were better at detecting foreground bars with a larger orientation contrast from uniformly oriented background bars. Saliency-sensitive signals were strongest in the superficial layers of the primary visual cortex (V1), and in the middle layers of the intraparietal sulcus (IPS) of the parietal cortex. Layer-dependent effective connectivity revealed the transmission of saliency signals along the feedforward pathway from V1 to IPS. Furthermore, behavioral sensitivity to the foreground stimulus correlated significantly with the fMRI response in the superficial layers of V1. Our findings provide mesoscale evidence that a visual saliency map is created by iso-feature suppression through lateral inhibition in the superficial layers of V1, and then feeds forward to attentional control brain regions to guide attention and eye movements.

neuroscience↗

bioRxiv2025

Deciphering complex interactions between LTR retrotransposons and three Papaver species using LTR_Stream

Long terminal repeat retrotransposons (LTR-RTs), a major type of class I transposable elements (TEs), are the most abundant repeat element in plants. The study of the interactions between LTR-RTs and the host genome relies on high-resolution characterization of LTR-RTs. However, for non-model species, this remains a challenge. To address this, we developed LTR_Stream for sub-lineage clustering of LTR-RTs in specific or closely related species, providing higher precision than current database-based lineage-level clustering. Using LTR_Stream, we analyzed Retand LTR-RTs in three Papaver species. Our findings show that high-resolution clustering reveals complex interactions between LTR-RTs and the host genome. For instance, we found autonomous Retand elements could spread among the ancestors of different subgenomes, like retroviruses pandemics, enriching genetic diversity. Additionally, we identified that specific truncated fragments containing transcription factors motifs such as TCP and bZIP may contribute to generation of novel TAD-like boundaries. Notably, our pre- and post-allopolyploidization comparisons show that these effects diminished after allopolyploidization, suggesting that allopolyploidization may be one of the mechanisms by which Papaver species cope with LTR-RTs. We demonstrated the potential application of LTR_Stream and provided a reference case for studying the interactions between LTR-RTs and the host genome in non-model plant species.

bioinformatics↗

bioRxiv2025

A Telomere-to-Telomere Diploid Reference Genome and Centromere Structure of the Chinese Quartet

Recent advances in sequencing technologies have enabled the complete assembly of human genomes from telomere to telomere (T2T), resolving previously inaccessible regions such as centromeres and segmental duplications. Here, we present an updated, higher-quality, haplotype-phased T2T assembly of the Chinese Quartet (T2T-CQ), a family cohort comprising monozygotic twins and their parents, generated using high-coverage ONT ultralong and PacBio HiFi sequencing. The T2T-CQ assembly serves as a crucial reference genome for integrating publicly available multi-omics data and advances the utility of the Quartet reference materials. The T2T-CQ assembly scores highly on multiple metrics of continuity and completeness, with Genome Continuity Inspector (GCI) scores of 77.76 (maternal) and 76.41 (paternal), quality values (QV) > 70, and Clipping Reveals Assembly Quality (CRAQ) scores > 99.6 for both haplotypes, enabling complete annotation of centromeric regions. Within these regions, we identified novel 13-mer higher-order repeat patterns on chromosome 17 which exhibited a monophyletic origin and emerged approximately 230 thousand years ago. Overall, this work establishes an essential genomic resource for the Han Chinese population and advances the development of a T2T pan-Chinese reference genome, which will significantly enable future investigations both into population-specific structural variants and the evolutionary dynamics of centromeres.

genomics↗

bioRxiv2025

Biosynthesis of modular signaling molecules requires functional diversification of carboxylesterases in Pristionchus pacificus

The model nematode Pristionchus pacificus produces four types of complex ascaroside pheromones named UBAS, DASC, NPAR, and PASC. However, the exact biosynthetic pathways of these modular signaling molecules remain enigmatic. We have previously identified a carboxylesterase Ppa-UAR-1 for the biosynthesis of UBAS, enabling the attachment of ureidoisobutyric acid at the 4-position of simple ascarosides. Here, we report three new carboxylesterases Ppa-UAR-5, Ppa-UAR-6 and Ppa-UAR-12 from P. pacificus. Ppa-UAR-5 functions downstream of Ppa-UAR-1 to furnish the biosynthesis of ubas#1 and ubas#2, whereas Ppa-UAR-12 specifically links two ascr#1 at the 4-position to synthesize dasc#1. Finally, Ppa-UAR-6 is essential for the biosynthesis of npar#1-3 and part#9. The expression patterns of Ppa-uar-6 and Ppa-uar-12 in the intestinal and epidermal cells suggest pheromone biosynthesis to be restricted to specific tissues. These findings indicate that the expansion and functional diversification of carboxylesterases plays a crucial role in the evolution of complex pheromones in nematodes. SIGNIFICANCEOur study identified three new carboxylesterase genes (Ppa-uar-5, Ppa-uar-12 and Ppa-uar-6) from P. pacificus. The encoded enzymes separately regulated the biosynthesis of three types of modular pheromones (UBAS, DASC, and NPAR-types) in worms intestinal cells and exhibited extremely high substrate-specificity. For example, we verified that Ppa-UAR-12 specifically linked one ascr#1 to the 4-position of another ascr#1 to finally furnish the biosynthesis of ascaroside dimer dasc#1. These new discoveries largely clarify the delicate biosynthetic mechanisms of how diversification of carboxylesterases functions in P. pacificus to build up enormous complexity of modular signaling molecules. Such a biosynthetic mechanism of nematode pheromones might be widely conserved in the phylum Nematoda.

biochemistry↗