Biology subjects

Lu, M.

Publications and source records attributed to Lu, M..

At least 55 records · Page 3Linked to original sources

bioRxiv2025

Chronic Infection Perturbs the Affinity Hierarchy of Antiviral B Cells

The germinal center (GC) subjects antigen-specific B cells to a Darwinian selection process. Whether and how persistent viral infection perturbs the intended affinity hierarchy remains ill-defined. Here we transferred monoclonal lymphocytic choriomeningitis virus-specific B cells into persistently infected hosts. High affinity B cells expanded vigorously, forming GCs and abundant antibody-secreting cells. When failing to gain the upper hand over the virus, the expanded B cell population contracted, ending in its quasi-complete disappearance, a process termed "attrition". In stark contrast, low-affinity B cells expanded and persisted irrespective of high viral loads. B cell attrition was associated with phenotypic and transcriptional alterations including a prominent Blimp-1 transcriptional signature in high-affinity GC B cells. Blimp-1-deficient B cells were resistant to attrition, suggesting a B cell-intrinsic process. Moreover, exogenously supplied antibody feedback prevented attrition, indicating the latter resulted from excessive stimulation. Our findings reveal that in chronic viral infection the incessant activation by overwhelming amounts of antigen perturbs B cell affinity hierarchies by preferentially dysregulating high-affinity B cells.

immunology↗

bioRxiv2025

Caffeic acid promoted deep vein thrombosis resolution in mice by suppressed macrophage M1 polarization through Keap1/Nrf2 pathwayv

BackgroundDeep vein thrombosis (DVT) carries significant health risks, with macrophages playing a key role in thrombus resolution. Caffeic acid (CA) has been shown to inhibit thrombosis, but its role in DVT resolution remains unclear. PurposeThis study aimed to investigates the effects and mechanisms of CA in accelerating DVT resolution. MethodsA stasis-type DVT model was established in mice via inferior vena cava ligation. The effects of CA were analyzed. Thrombus resolution was assessed using histological staining, gelatin zymography, immunoblotting, and immunofluorescence. Macrophage depletion was conducted with chlorophosphate liposomes, and bone marrow-derived macrophages (BMDMs) were used for polarization studies. RNA sequencing identified potential molecular pathways. Nrf2 gene-deficient mice were used to verify the role of Nrf2 in deep vein thrombus resolution. ResultsCaffeic acid reduced thrombus size, enhanced collagenolysis via increased MMP-2 activity, promoted neovascularization, increased macrophage infiltration, and suppressed M1 polarization and inflammation. CA activated the nuclear factor erythroid 2-related factor 2 (Nrf2) pathway by inhibiting Keap1, leading to enhanced antioxidant responses in both BMDMs and thrombus tissue. Macrophage depletion negated CAs benefits, confirming the central role macrophages. ConclusionCA promoted early thrombus resolution via macrophage recruitment, M1 polarization suppression, and Nrf2 activation, highlighting its potential as a preventive strategy for DVT.

pharmacology and toxicology↗

bioRxiv2025

Structural Basis for Cas9-Directed Spacer Acquisition in Type II-A CRISPR-Cas Systems

CRISPR-Cas systems confer prokaryotic adaptive immunity by integrating foreign DNA (prespacers) into host arrays. Type II-A systems employ Cas9 for protospacer adjacent motif (PAM) recognition and coordinate with Csn2 and the Cas1-Cas2 integrase during spacer acquisition, yet their structural basis remains unresolved. Here, we report cryo-EM structures of the Enterococcus faecalis Cas9-Csn2-Cas1-Cas2 supercomplex in apo and DNA-bound states. The apo-state structure (Cas92-Csn28-Cas18-Cas24) adopts a resting conformation, with Cas9 locked in a nuclease-inactive state and Cas1-Cas2 sterically blocked from prespacer loading. Upon DNA engagement, Cas9 undergoes a conformational transition, forming a prespacer catching complex that threads the DNA through Csn2s central channel. This architecture enables Cas9 to interrogate the PAM sequence while sliding along the DNA, with Cas9 and Csn2 jointly define a 30-bp DNA segment which matches the prespacer length. Subsequent dissociation of Cas9 triggers a structural reconfiguration of the Csn2-Cas1-Cas2 assembly. The PAM-proximal DNA becomes accessible, and Cas1-Cas2 relocates to bind to the exposed DNA, enabling further prespacer processing and directional integration. These findings reveal how Cas9 collaborates with Csn2 and Cas1-Cas2 to couple PAM recognition with prespacer selection, resolving the dynamic structural transitions that ensure fidelity during type II-A CRISPR adaptation.

molecular biology↗

bioRxiv2025

Brain cholesterol metabolites cause significant neurodegeneration in human iPSC-derived neurons

Disrupted cholesterol metabolism is increasingly recognised as a contributing factor in neurodegeneration; however, the specific effects of key brain-derived cholesterol metabolites, 24S-hydroxycholesterol (24S-HC) and 27-hydroxycholesterol (27-HC), remain poorly understood. Using human iPSC-derived i3 cortical neurons, we demonstrate that both 24S-HC and 27-HC significantly impair neuronal calcium signalling by elevating resting calcium levels, reducing spike amplitude, and disrupting network synchrony. These functional deficits are accompanied by widespread organelle dysfunction. Both oxysterols induce mitochondrial fragmentation, decrease spare respiratory capacity, and impair lysosomal degradation. Notably, 27-HC uniquely triggers lysosomal swelling and membrane permeabilisation. Additional signs of cellular stress, including axonal swellings and elevated endoplasmic reticulum calcium levels, were also observed. Furthermore, both 24S-HC and 27-HC were found to directly interact with alpha-synuclein (aSyn), promoting its accumulation in cellular models. In contrast, cholesterol itself had minimal impact, highlighting the distinct toxicity of its hydroxylated metabolites. Together, these findings reveal a mechanistic link between oxysterol accumulation and neuronal dysfunction, supporting the hypothesis that elevated levels of 24S-HC and 27-HC, commonly observed in Parkinsons and Alzheimers disease, may actively drive neurodegenerative processes. Targeting oxysterol metabolism may therefore represent a promising therapeutic avenue for intervention in neurodegenerative disorders.

neuroscience↗

bioRxiv2025

Efficacy of DNA Methyltransferase Inhibitor Immune Priming Therapy in Combination with PD-1 Inhibitors to Treat High-Risk Pediatric Brain Tumors

BackgroundDespite intensive therapies, outcomes for high-risk pediatric brain tumors (PBTs) remain dismal, prompting the search for novel treatments. DNA methyltransferase inhibitors (DNMTi) have been shown to prime tumors to improve response to checkpoint inhibition. The aim of this study was to investigate the potential of decitabine (DAC), in combination with a PD-1 inhibitor, to improve survival in pediatric high-risk brain tumor models. MethodsAnalysis of human PBT datasets was performed to determine gene expression levels of immune cell associated markers. Tumor response to DAC, with or without a PD-1 inhibitor, was tested in murine models representing H3-wildtype diffuse intrinsic pontine glioma (DIPG), H3K27-mutant diffuse midline glioma (DMG), atypical teratoid rhabdoid tumor (ATRT), and medulloblastoma (MB). CyTOF analysis of allograft tumors was performed to characterize changes within the tumor microenvironment. ResultsAnalysis of PBT subtypes revealed heterogeneous expression of immune cell markers, checkpoint receptors, and MHC molecules. DAC treatment decreased DNA methylation and increased neoantigen expression in human and mouse tumor cells. DAC alone or in combination with a PD-1 inhibitor resulted in prolonged survival in syngeneic mouse models of DIPG and ATRT but not DMG and MB models. CyTOF analysis of mouse tumors revealed changes in local immune cell infiltration upon combination treatment. ConclusionsDAC in combination with a PD-1 inhibitor can alter the immune microenvironment in mouse tumor models. Changes were observed in H3-wildtype DIPG and ATRT models, suggesting that certain tumor subtypes may respond to checkpoint blockade after immune augmentation with DNMTi. Key PointsO_LIPBTs show heterogenous expression of immune cell infiltrates C_LIO_LIDAC or DAC plus a PD-1 inhibitor shows extension of survival in H3-wildtype DIPG and ATRT mouse models C_LIO_LIMyeloid-derived suppressor cell abundance could be a major contributing factor to treatment response C_LI Importance of the StudyChildren with high-risk PBTs face dismal outcomes. Immune checkpoint inhibitor (ICI) successes have been demonstrated in a variety of adult malignancies; however, such beneficial outcomes have not been realized in PBTs. Here we investigate single and combination treatment of DNMTi and PD-1 checkpoint inhibition in syngeneic mouse models of high-risk PBTs. Our results suggest that some H3-wildtype DIPG and ATRT tumor types may be responsive to checkpoint therapy post immunomodulation and warrant further investigation.

immunology↗

bioRxiv2025

Aird-MSI: a high compression rate and decompression speed format for mass spectrometry imaging data

Mass spectrometry imaging has emerged as a pivotal tool in spatial metabolomics, yet its reliance on the imzML format poses critical challenges in data storage, transmission, and computational efficiency. While imzML ensures cross-platform compatibility, its lower compressed binary architecture results in large file sizes and high parsing overhead, hindering cloud-based analysis and real-time visualization. This study introduces an enhanced Aird compression format optimized for spatial metabolomics through two innovations: (1) a dynamic combinatorial compression algorithm for integer-based encoding of m/z and intensity data; (2) a coordinate-separation storage strategy for rapid spatial indexing. Experimental validation on 47 public datasets demonstrated significant performance gains. Compared to imzML, Aird achieved a 70% reduction in storage footprint (mean compression ratio: 30.03%) while maintaining near-lossless data precision (F1-score = 99.26% at 0.1 ppm m/z tolerance). For high-precision-controlled datasets, Aird accelerated loading speeds by 15-fold in MZmine. The Aird format overcomes crucial bottlenecks in spatial metabolomics by harmonizing storage efficiency, computational speed, and analytical precision, reducing I/O latency for large cohorts. By achieving near-native feature detection accuracy, Aird establishes a robust infrastructure for translational applications, including disease biomarker discovery and pharmacokinetic imaging.

bioinformatics↗

bioRxiv2025

Breakthrough infection elicits synergistic broadly neutralizing antibodies targeting non-dominant epitopes on RBD and NTD in an individual of inactivated SARS-CoV-2 vaccine

Background/ObjectivesIdentification and characterization of broadly neutralizing monoclonal antibodies from individuals exposed to SARS-CoV-2, either by infection or vaccination, can inform the development of next-generation vaccines and antibody therapeutics with pan-SARS-CoV-2 protection. MethodsThrough single B cell sorting and RT-PCR, monoclonal antibodies (mAbs) were isolated from a donor who experienced BA.5 or BF.7 breakthrough infection after three doses of inactivated vaccines. Their binding and neutralizing capacities were respectively measured with ELISA and pseudovirus-based neutralization assay. Their epitopes were mapped by competition ELISA and site- directed mutation. ResultsAmong a total of 67 spike-specific mAbs cloned from the donor, four mAbs (KXD643, KXD652, KXD681, and KXD686) can neutralize all tested SARS-CoV-2 variants from wild-type to KP.3. Moreover, KXD643, KXD652, and KXD681 belong to a clonotype encoded by IGHV5-51 and IGKV1-13, and recognize the cryptic and conserved RBD-8 epitope on the receptor-binding domain (RBD). In contrast, KXD686 is encoded by IGHV1-69 and IGKV3-20, and targets a conserved epitope (NTD Site iv) outside the antigenic supersite (NTD Site i) of the N-terminal domain (NTD). Notably, antibody cocktails containing these two groups of mAbs can neutralize SARS-CoV-2 more potently due to synergistic effects. In addition, bispecific antibodies derived from KXD643 and KXD686 demonstrate further improved neutralizing potency compared to antibody cocktails. ConclusionsThese four mAbs can be developed as candidates of pan-SARS-CoV-2 antibody therapeutics through further antibody engineering. On the other hand, vaccines designed to simultaneously elicit neutralizing antibodies towards RBD-8 and NTD Site iv have the potential to provide pan-SARS-CoV-2 protection.

immunology↗

bioRxiv2025

Continental-scale relationships of fine root and soil carbon stocks hold in grasslands but not forests

Increasing root carbon inputs into soils has been proposed as a solution to increasing soil organic carbon (SOC). However, while fine root carbon (FRC) inputs can increase SOC accrual in soils, FRC can also enhance SOC loss by stimulating microbial respiration and cause a net loss of SOC through priming. It remains unclear how SOC varies as a function of FRC at broad spatial scales and across ecosystems and depths. Here, we tested the relationship of SOC and FRC using data from 43 sites across the US National Ecological Observatory Network (NEON). We found that total stocks of SOC and FRC in the top 2 meters of soil were positively related with an across-ecosystem slope of 7 {+/-} 3 kg SOC m-2 per kg FRC m-2. However, grassland sites primarily drove this relationship. Grasslands had 15 {+/-} 2 kg SOC m-2 per kg FRC m-2, which is double the across-ecosystem slope. We used deviations from the standardized 1:1 relationship between FRC and SOC to infer whether ecosystems were net priming (indicated by observed SOC being lower than the 1:1 line) or SOC accruing (higher SOC than the 1:1 line). Grassland soils and especially their deep soil layers (>30 cm) showed primarily SOC accrual with increasing fine root abundance. Meanwhile, forest soils had high variability in whether increasing fine roots were associated with net SOC priming or accrual across both shallow and deeper soil layers. We found that in grasslands, FRC inputs are strongly related to SOC accrual, especially at depth and at sites with high moisture and clay content. In contrast, SOC-FRC relationships in forests remain difficult to characterize. Nevertheless, deep grassland soils may serve as optimal environments in which increasing FRC could lead to meaningful increases in SOC stocks.

ecology↗

bioRxiv2025

A Single-Cell Atlas of RNA Alternative Splicing in the Glioma-Immune Ecosystem

Single-cell analysis has refined our understanding of cellular heterogeneity in glioma, yet RNA alternative splicing (AS)--a critical layer of transcriptome regulation--remains underexplored at single-cell resolution. Here, we present a pan-glioma single-cell AS analysis in both tumor and immune cells through integrating seven SMART-seq2 datasets of human gliomas. Our analysis reveals lineage-specific AS across glioma cellular states, with the most divergent AS landscapes between mesenchymal- and neuronal-like glioma cells, exemplified by AS in TCF12 and PTBP2. Comparison between core and peripheral glioma cells highlights AS-redox co-regulation of cytoskeleton organization. Further analysis of glioma-infiltrating immune cells reveals potential isoform-level regulation of protein glycosylation in regulatory T cells and a link between MS4A7 AS in macrophages and clinical response to anti-PD-1 therapy. This study emphasizes the role of AS in glioma cellular heterogeneity, highlighting the importance of an isoform-centric approach to better understand the complex biological processes driving tumorigenesis.

genomics↗

bioRxiv2025

AlphaFold3 and RoseTTAFold All-Atom structures enable radiosensitizers discovery by targeting multiple DNA damage repair proteins

Radioresistance remains a primary obstacle in tumor radiotherapy, with no clinically approved radiosensitizers due to toxicity concerns. To identify effective and safe radiosensitizers, a natural products database containing 79,263 compounds are docked against a hybrid target library of four DNA damage response (DDR)-related proteins, comprising both experimental and artificial intelligence (AI)-predicted structures generated by AlphaFold3 and RoseTTAFold All-Atom models. Retrospectively, AI-modeled structures show comparable AUC and logAUC values to experimental structures. Prospectively, compounds screened by AI-modeled structures versus those by experimental structures exhibit limited overlap, e.g., 10% for ataxia telangiectasia mutated (ATM), 22.2% for ATM- and Rad3-related (ATR), 7.7% for DNA-dependent protein kinase catalytic subunit (DNA-PKcs), and 40% for Poly (ADP-ribose) polymerase 1 (PARP1). This highlights structural complementarity of AI-modeled structures when docking against small-scale compound libraries. Two compounds exhibiting lower binding free energy than the DNA-PKcs co-crystallized ligand were selected and validated as effective radiosensitizers in tumor cells. Proteomic analyses reveal shared DDR dysregulation but distinct repair pathway vulnerabilities behind both compounds, which activate TP53-associated apoptosis and senescence as cellular endpoints by modulating the synergistic interplay between DDR and spindle checkpoints. These findings highlight their potential as context-dependent radiosensitizers, providing novel candidates and strategies to overcome tumor radioresistance.

cancer biology↗

bioRxiv2025

MIR192 Upregulates GLP-1 Receptor and Improves Statin-Induced Impairment of Insulin Secretion

Statins are a commonly prescribed cholesterol lowering drug class that can increase the risk of new-onset diabetes (NOD). To investigate the molecular mechanisms underlying this effect, we generated human induced pluripotent stem cells (iPSCs) from individuals identified from electronic health records of Kaiser Permanente of Northern California who were susceptible to developing NOD after statin initiation or controls who maintained stable fasting glucose on statin treatment. RNA-seq analysis of iPSCs incubated with atorvastatin, simvastatin or mock buffer for 24 hours identified the long non-coding RNA MIR194-2HG as a top candidate gene. Statin-induced increases in its expression were observed in NOD resistant controls, while statin-induced reductions occurred in NOD susceptible cases. MIR194-2HG encompasses two microRNA genes: MIR192 and MIR194-2. The mature microRNA miR-192-5p, derived from the 5 arm of MIR192, was predicted to bind the 3UTR of the glucagon like peptide 1 (GLP-1) receptor (GLP1R) transcript. Transfection of a rat insulinoma cell line INS-1 with a miR-192-5p mimic increased Glp1r transcript (1.41-fold) and protein (1.51-fold) levels compared to a scrambled control. Using a luciferase reporter containing the human GLP1R 3UTR, miR-192-5p overexpression similarly increased luciferase signal (1.44-fold). The miR-192-5p mimic enhanced glucose stimulated insulin secretion (GSIS) in response to GLP1R agonists (1.64-1.81-fold) and rescued simvastatin-induced GSIS impairment in INS-1 cells. Wild-type mice treated with miR-192 AAV8 had improved glucose sensitivity. Islets isolated from these mice exhibited enhanced GLP-1 potentiated GSIS during perifusion ex vivo. These effects were absent in the DIRKO (Glp1r/Gipr double knockout) mouse islets, consistent with the idea that miR-192 promotes GLP-1 mediated GSIS through GLP1R. These findings implicate MIR192 in statin-induced impairment of GSIS by modulating GLP1R, potentially contributing to the susceptibility to NOD in statin users.

cell biology↗

bioRxiv2025

Detection of Diffuse to Focal Myocardial Fibrosis by Cardiovascular Magnetic Resonance Against Histology in Mini-Swine

BackgroundMyocardial fibrosis predicts adverse outcomes in myocardial infarction (MI) and other cardiovascular conditions. Cardiovascular magnetic resonance (CMR) can non-invasively detect focal and diffuse myocardial fibrosis, but comprehensive validation against histology remains scarce. AimsTo assess the comparative diagnostic performance of CMR methods in detecting myocardial fibrosis, using a mini-swine model and histology as gold standard. MethodsEighteen mini-swine (16 MI; 2 healthy) underwent CMR cine, LGE, T1- and ECV-mapping. Two commonly-used T1-mapping methods - MOLLI 5(3)3 and ShMOLLI 5(1)1(1)1 - were included. Pathological sections were categorized as infarcted, peri-infarct, remote and healthy myocardium based on triphenyl tetrazolium chloride staining. Fibrotic burden was quantified by collagen volume fraction (CVF) into severe (CVF[≥]30%), moderate (CVF=10-25%), and mild (CVF=3-14%). The relationships between LGE, T1, ECV and CVF, and diagnostic performance using area-under-the-curve (AUC), were analyzed. ResultsFor detecting severe fibrosis, LGE, T1 and ECV all had excellent diagnostic performance (AUC: LGE=0.93, ECVShMOLLI=0.96, T1ShMOLLI=0.91, T1MOLLI=0.93, ECVMOLLI=0.88). ECVShMOLLI showed significantly better discriminatory accuracy than ECVMOLLI in detecting severe fibrosis and MI (both p<0.05), with the highest correlation to CVF (ECVShMOLLI r=0.86, ECVMOLLI r=0.82, T1ShMOLLI r=0.77, T1MOLLI r=0.77, semi-quantitative LGE r=0.75). Only T1ShMOLLI and ECVShMOLLI, but not LGE or T1MOLLI/ECVMOLLI, differentiated remote myocardium with mild fibrosis (CVF=8.23%) from healthy myocardium (CVF=2.01%). ConclusionsCMR can detect severe to mild myocardial fibrosis as validated against histology. For low-grade fibrosis, T1-mapping significantly outperformed LGE. Choice of CMR methodologies matters for myocardial fibrosis detection, which has importance for clinical trial design.

pathology↗

bioRxiv2025

LCORL and STC2 variants increase body size and growth rate in cattle and other animals

Using ancestral recombination graphs, we investigated recent selection signatures in European beef cattle breeds, pinpointing sweep-driving variants in the LCORL and STC2 loci with notable effects on body size and growth rate. The ACT-to-A frameshift mutation in LCORL occurs mainly in central-European cattle, and stimulates growth. Remarkably, convergent truncating mutations were also found in commercial breeds of sheep, goats, pigs, horses, dogs, rabbits, and chickens. In the STC2 gene, we identified a missense mutation (A60P) located within the conserved region across vertebrates. We validated the two natural mutations in gene-edited mouse models, where both variants in homozygous carriers increase the average weight by 11%. Our findings provide insights into a seemingly recurring gene target of body size enhancing truncating mutations across domesticated species, and offer valuable targets for gene editing-based breeding in animals.

genetics↗

bioRxiv2024

Characterizing Tyrosine Ring Flips in Proteins by 19F NMR

Aromatic ring-flip dynamics are hallmarks of concerted protein "breathing" motions that are essential for biological function. Ring flips occur on a broad range of timescales (ns-s) and have been primarily studied by NMR spectroscopy, typically requiring expensive isotope labeling of aromatic side chains, thereby limiting such studies to a few proteins. Here, we report two novel di-fluorotyrosine probes, 3,5-F2Y and 2,6-F2Y, that can be incorporated into proteins cost-effectively for characterizing and modulating tyrosine ring-flip dynamics. We show that 19F rotating-frame (R1{rho}) relaxation dispersion is powerful for quantifying ring flips on the {micro}s-ms timescale. Importantly, the tyrosine ring-flip rates (kflip) for 3,5-F2Y in GB1 and HPr are comparable to those measured by 1H and 13C NMR studies, validating 3,5-F2Y as a largely non-perturbing, native-like ring-flip probe. In contrast, 2,6-F2Y acts as an effective "brake" on ring flips, enabling direct visualization and quantitative characterization of previously undetected tyrosine ring flips in ubiquitin via 19F lineshape analysis. Furthermore, we use 2,6-F2Y to assess the environmental effects on ring-flip dynamics in crowding reagents and in living X. laevis oocytes. Collectively, our study opens a new avenue for measuring and modulating ring-flip dynamics in vitro and in living cells. TOC O_FIG O_LINKSMALLFIG WIDTH=200 HEIGHT=165 SRC="FIGDIR/small/630691v2_ufig1.gif" ALT="Figure 1"> View larger version (61K): org.highwire.dtl.DTLVardef@dcf8e1org.highwire.dtl.DTLVardef@1578887org.highwire.dtl.DTLVardef@1c481d0org.highwire.dtl.DTLVardef@268ae0_HPS_FORMAT_FIGEXP M_FIG C_FIG

biochemistry↗

bioRxiv2024

Lotus japonicus VIH2 is an inositol pyrophosphate synthase that regulates arbuscular mycorrhiza

Plant yield is often maximized by the extensive use of mineral fertilizers, which, however, has severe environmental consequences. Phosphate is particularly problematic, as it represents a globally limited resource, and its runoff and soil erosion threaten open water bodies. Many crops engage in arbuscular mycorrhizal (AM) symbiosis with nutrient-acquiring fungi, aiding in the uptake of phosphate and other mineral nutrients. However, AM colonization is strongly reduced under high soil phosphate levels. A mechanistic understanding of phosphate sensing, phosphate starvation responses, and their connection to AM remains enigmatic. Here, we show that in Lotus japonicus, low-abundant, energy-rich inositol pyrophosphates act as master regulators of AM, orchestrating the crosstalk between phosphate starvation responses and plant root endosymbiosis. These findings hold promise for breeding nutrient-efficient crops.

plant biology↗

bioRxiv2024

Scaling ecological niches from individuals to populations and beyond

The niche is a key concept that unifies ecology and evolutionary biology. However, empirical and theoretical treatments of the niche are mostly performed at the species level, neglecting individuals as important units of ecological and evolutionary processes. So far, a formal mathematical link between individual-level niches and higher organismal-level niches has been lacking, hampering the unification of ecological theories and more accurate forecasts of biodiversity change. To fill in this gap, we propose a bottom-up approach to derive population and higher organismal-level niches from individual niches. We demonstrate the power of our framework by showing that 1) the statistical properties of higher organismal-level niches (e.g. niche breadth, skewness etc.) can be partitioned into individual contributions; 2) the species-level niche shifts can be estimated by tracing the responses of individuals. Our method paves the way for a unifying niche theory and enables mechanistic assessments of organism-environment relationships across organismal scales.

ecology↗

bioRxiv2024

Coordination of flux-related leaf and root traits impacts forest community assembly

Understanding the functions and coordination of plant traits is critical for predicting how diverse species respond to climate change. According to hydraulic and economic theories, leaves and roots--key organs for resource acquisition--are expected to function in coordination, such that species with faster resource utilization would possess leaf and root traits that facilitate rapid carbon, nutrient, and water uptake and fluxes. However, there has been limited evidence supporting leaf-root trait coordination and a role for that coordination on community structure. Here, we measured 13 leaf and root functional traits for 101 woody species from six tropical and subtropical forests, and assessed coordination and its association with community dominance. Hydraulic traits, such as leaf vein density and root vessel density, were coordinated between organs and showed compensation trade-offs between traits within organs, such as, leaf vein density and diameter. Economic traits relating to composition, such as nitrogen concentration, were coordinated between organs, whereas economic structural traits were decoupled, such as leaf mass per area and specific root length. Overall, hydraulic traits and economics traits were partially independent. The coordination of flux-related leaf and root traits was associated with ectomycorrhizal symbiosis and with dominance within the community. These findings indicate how trait organization within and across organs contributes to optimal whole plant function, with implications for performance in natural communities.

ecology↗

bioRxiv2024

Longitudinal profiling of B cells primed by mRNA vaccine and recalled by Omicron variants uncovers antibodies broadly neutralizing sarbecoviruses

A key question on ancestral SARS-CoV-2 immune imprinting is to what extent imprinted B cells can develop neutralizing breadth and potency in immune recalls. Here, we longitudinally tracked B cells recognizing wild-type spike in two individuals, who were sequentially infected by Omicron variants after receiving mRNA vaccines. Functional and genetic analysis of 632 monoclonal antibodies (mAbs) from those B cells reveals that mAbs cloned after second infection have dramatically enhanced neutralizing breadth and potency, which is attributed to recall and maturation of pre-existing memory B cells. Among the 11 mAbs that potently neutralize SARS-CoV-2 variants from wild-type to KP.3, 5 mAbs are classified into public clonotypes encoded by IGHV3-53 or IGHV3-66, whereas the rest belong to a rarely reported clonotype encoded by IGHV3-74. Notably, IGHV3-74 mAbs can also broadly neutralize other sarbecoviruses by targeting a novel epitope on receptor-binding domain of spike. These results support that ancestral SARS-CoV-2 immune imprinting can be harnessed in developing pan-SARS-CoV-2 and even pan-sarbecovirus vaccines. SummaryChen et al. demonstrate that B cells imprinted by ancestral SARS-CoV-2 have tremendous potential to develop neutralizing breadth and potency in repeated immune recalls driven by Omicron variants, implicating that ancestral SARS-CoV-2 immune imprinting can be harnessed in developing pan-SARS-CoV-2 and even pan-sarbecovirus vaccines.

immunology↗