Biology subjects

Wu, X.

Publications and source records attributed to Wu, X..

At least 361 records · Page 20Linked to original sources

bioRxiv2023

Evolution of the gene regulatory network of body axis by enhancer hijacking in amphioxus

A central goal of evolutionary developmental biology is to decipher the evolutionary pattern of gene regulatory networks (GRNs) that control morphogenesis during embryonic development, and the underlying molecular mechanism of the GRNs evolution. The Nodal signaling that governs the body axes of deuterostomes exhibits a conserved GRN orchestrated principally by Nodal, Gdf1/3 and Lefty. Despite that the GRN retains a conserved function in deuterostomes, the expression patterns of Gdf1/3 and Nodal are derived in cephalochordate amphioxus, implying a specific rewiring of the GRN in this lineage. Here we examined the regulatory mechanism and evolution of this GRN in amphioxus by functional genetic manipulations. We found that while the amphioxus Gdf1/3 orthologue shows nearly no expression during embryogenesis, its duplicate Gdf1/3-like linking to Lefty is zygotically expressed in a similar pattern as Lefty. Mutant and transgenic analyses revealed that Gdf1/3 is no longer crucial for amphioxus axial development. Instead, Gdf1/3-like assumes this responsibility, likely through hijacking Lefty enhancers. We also showed that amphioxus Nodal has become an indispensable maternal factor to compensate for the loss of maternal Gdf1/3 expression. We therefore demonstrated a case that the evolution of an ancestral GRN could be triggered by enhancer hijacking events. This pivotal event has allowed the emergence of a new GRN in the extant amphioxus, presumably evolving through a stepwise process. The co-expression of Gdf1/3-like and Lefty achieved by shared regulatory region may have provided developmental robustness during body axis formation in extant amphioxus, which provides a selection-based hypothesis for the phenomena called developmental system drift.

evolutionary biology↗

bioRxiv2023

Consensus peaks of chromatin accessibility in the human genome

The rapid advancement of transposase-accessible chromatin using sequencing (ATAC-seq) technology, particularly with the emergence of single-cell ATAC-seq (scATAC-seq), has accelerated the studies of gene regulation. However, the absence of a generic feature reference for ATAC-seq data limits single-cell analyses and hinders the development of comprehensive cell atlases. To address this, we constructed a generic chromatin accessibility reference by aggregating peaks from 624 high-quality bulk ATAC-seq datasets, defining more than 1 million consensus peaks (cPeaks). Leveraging a deep neural network model, we expanded cPeaks to include previously unobserved regions, enhancing their coverage across diverse tissues and cell types. cPeaks exhibit consistent shapes across tissue types, sequencing technologies, and peak-calling methods, indicating that they represent inherent genomic features. Compared to existing feature defining methods and references, cPeaks show superior performance in scATAC-seq analyses, improving cell annotation and rare cell type identification. Additionally, cPeaks provide insights into chromatin dynamics during cellular differentiation and tumor progression. cPeaks can serve as a robust reference for chromatin accessibility studies to promote cross-dataset consistency and accelerate biological discoveries.

bioinformatics↗

bioRxiv2023

Shortcut barcoding and early pooling for scalable multiplex single-cell reduced-representation CpG methylation sequencing at single nucleotide resolution

DNA methylation is essential for a wide variety of biological processes, yet the development of a highly efficient and robust technology remains a challenge for routine single-cell analysis. We developed a multiplex scalable single-cell reduced representation bisulfite sequencing (msRRBS) technology with off-the-shelf reagents and equipment. It allows cell-specific barcoded DNA fragments of individual cells to be pooled before bisulfite conversion, free of enzymatic modification or physical capture of the DNA ends, and achieves unparalleled read mapping rates of 62.51%, covering 59.95% of CpG islands and 71.62% of promoters in K562 cells on average. Its reproducibility is shown in duplicates of bulk cells with near perfect correlation (R=0.97-99). At a low 1 Mb of clean reads, msRRBS provides consistent coverage of CpG islands and promoters, outperforming the conventional methods with orders of magnitude reduction in cost. Here, we use this method to characterize the distinct methylation patterns and cellular heterogeneity of 6 cell lines, and leukemia and hepatocellular carcinoma models. Taking 4 hours of hands-on time, msRRBS offers a unique, highly efficient approach for dissecting methylation heterogeneity in a variety of multicellular systems.

genomics↗

bioRxiv2023

Structural Visualization of HECT-E3 Ufd4 accepting and transferring Ubiquitin to Form K29/K48-branched Polyubiquitination on N-degron

The K29/K48-linked ubiquitination generated by the cooperative catalysis of E3 ligase Ufd4 and Ubr1 is an enhanced protein degradation signal, in which Ufd4 is responsible for introducing K29-linked ubiquitination to K48-linked ubiquitin chains to augment polyubiquitination. How HECT-E3 ligase Ufd4 mediates the ubiquitination event remains unclear. Here, we biochemically determine that Ufd4 preferentially catalyses K29-linked ubiquitination on K48-linked ubiquitin chains to generate K29/K48-branched ubiquitin chains and capture structural snapshots of Ub transfer cascades for Ufd4-mediated ubiquitination. The N-terminal ARM region and HECT domain C-lobe of Ufd4 are identified and characterized as key structural elements that together recruit K48-linked diUb and orient Lys29 of its proximal Ub to the active cysteine of Ufd4 for K29-linked branched ubiquitination. These structures not only provide mechanistic insights into the architecture of the Ufd4 complex but also provide structural visualization of branched ubiquitin chain formation by a HECT-type E3 ligase.

biochemistry↗

bioRxiv2023

Cardiac Effects of a Novel pH-Insensitive Sodium-Calcium Exchanger Mouse

BACKGROUNDCardiac sodium-calcium exchange (NCX1) is the dominant calcium (Ca) efflux mechanism in cardiomyocytes and is strongly regulated by pH. However, the role of NCX1 pH sensitivity in normal cardiac function is unknown. METHODSWe used CRISPR/Cas9 to produce a pH-resistant NCX1 mouse by replacing the histidine at position 165 of NCX1 with an alanine (H165A). Hearts were studied using echocardiography and ECG. RNA and protein expression levels were assessed using qPCR and Western blotting. Isolated ventricular cardiomyocytes were loaded with Ca indicators and patch clamped to record intracellular Ca transients and membrane current and voltage. RESULTSH165A mice live into adulthood with slightly reduced LV systolic function, normal heart rate and shortened QT interval. Both male and female animals exhibit reduced growth, but females eventually reach normal body weight. In patch clamped myocytes, NCX current (INCX) evoked by voltage ramps was reduced by 35% (at +80 mV). Lowering pHi to 6.5 using Na-Acetate had no effect on INCX in H165A myocytes, whereas the same intervention in wildtype (WT) inhibited INCX by 69% (at +80 mV, p<0.01). There was no change in H165A ventricular cardiomyocyte Ca transients measured with fura-2 AM. However, action potential duration was reduced 68%, consistent with the shorter QT interval. This coincided with a 37% reduction in L-type Ca current and increased expression of repolarizing K+ channels. H165A mice are also resistant to ischemia/reperfusion injury. CONCLUSIONSThe H165A mutation attenuates pH regulation of NCX1 in mice, is associated with reduced growth and accelerates cardiac repolarization without compromising excitation-contraction coupling. The mutation also confers cardioprotection. The H165A mouse is the first evidence that pH regulation of NCX1 affects cardiac physiology and is a potential model for studying the role of NCX1 pH-sensitivity on both physiological and pathophysiological cardiac function.

biophysics↗

bioRxiv2023

A murine commensal protozoan relieves Clostridium difficile infection through regulating the arginine metabolism and the host intestinal immune response

Antibiotic-induced dysbiosis is a key predisposing factor for Clostridium difficile infection (CDI), fecal microbiota transplantation (FMT) is recommended for treating CDI. However, the mechanisms remain unclear. Here, we uncover that one integral member of the murine gut microbiota, a commensal protozoan from mice, Tritrichomonas musculis (T. mu), that reduced intestinal damage by inhibiting the recruitment of neutrophil and secretion of IL-1{beta}, and increased Th1 cell differentiation and secretion of IFN-{gamma}, which increased the goblet cell and secretion of mucin to protect the intestinal mucosa. The T. mu upregulated the key enzymes of arginine metabolism iNOS, ASS, OTC and down-regulated ARG1 in CDI mice, resulting in an increase in arginine, citrulline and a decrease in ornithine, which worked together to regulate the host intestinal immune response and alleviate CDI. This work reveals the interaction mechanism between intestinal commensal eukaryotes and pathogenic bacteria, and also provide new ideas for treating CDI.

microbiology↗

bioRxiv2023

CcBHLA: pan-specific peptide-HLA class I binding prediction via Convolutional and BiLSTM features

Human major histocompatibility complex (MHC) proteins are encoded by the human leukocyte antigen (HLA) gene complex. When exogenous peptide fragments form peptide-HLA (pHLA) complexes with HLA molecules on the outer surface of cells, they can be recognized by T cells and trigger an immune response. Therefore, determining whether an HLA molecule can bind to a given peptide can improve the efficiency of vaccine design and facilitate the development of immunotherapy. This paper regards peptide fragments as natural language, we combine textCNN and BiLSTM to build a deep neural network model to encode the sequence features of HLA and peptides. Results on independent and external test datasets demonstrate that our CcBHLA model outperforms the state-of-the-art known methods in detecting HLA class I binding peptides. And the method is not limited by the HLA class I allele and the length of the peptide fragment. Users can download the model for binding peptide screening or retrain the model with private data on github (https://github.com/hongliangduan/CcBHLA-pan-specific-peptide-HLA-class-I-binding-prediction-via-Convolutional-and-BiLSTM-features.git).

bioinformatics↗

bioRxiv2023

Single-cell RNA-sequencing identifies a novel subset of CD9+ reparative macrophages modulated by CCN2 derived from Nlrx1 deficient cardiomyocytes in the infarcted heart

RationaleNlrx1, a pattern recognition receptor belonging to the NLR family, is highly expressed in the heart and is significantly increased after myocardial infarction in vivo, however, the role of Nlrx1 in post-infarction inflammation and healing is poorly understood. Although the effects of infiltrating macrophages on survival of cardiomyocytes and healing of injured hearts have been intensely studied, whether or not and how surviving cardiomyocytes might influence the phenotype and function of macrophages in the infarcted hearts was largely unexplored. ObjectiveTo investigate the role of Nlrx1 in post-infarction inflammation and healing and to dissect the underlying mechanism. Methods and resultsSingle cell RNA-sequencing of 23,805 cells isolated from infarcted hearts revealed 7 clusters of infarct macrophages including CCR2+, Isg+, Mki67+ proliferative, and LYVE1+ cardiac resident macrophages, and identified a novel subset of CD9+Il1rn+ macrophages, which were characterized by high expression of Cd9, Il1rn, Gpnmb and Spp1, and downregulation of proinflammatory cytokines and chemokines. CD9+Il1rn+ macrophages were largely found in infarcted hearts of Nlrx1KO mice, and were transcriptionally unique with reparative phenotype. Loss of Nlrx1 attenuated ventricular dysfunction and adverse remodeling, and decreased post-infarction mortality. Flow cytometry analysis showed markedly increased number of CD9+ macrophages and higher mean fluorescence intensity of CD9 in Nlrx1KO mice. RNA-seq analysis revealed that CD9+ macrophages of Nlrx1KO infarcted hearts exhibited a reparative and anti-inflammatory phenotype as featured by upregulation of wound healing-associated genes including CD9, Spp1 and Fn1, and downregulation of proinflammatory genes. Conditioned medium from Nlrx1 deficient cardiomyocytes upon hypoxia stimulation skewed macrophage polarization towards a reparative and inflammation-suppressed phenotype. Gain-and loss-of function of Nlrx1 combined with RNA-seq analysis identified CCN2, whose expression and secretion were significantly increased in Nlrx1 deficient cardiomyocytes upon hypoxia, as a cardiomyocytes-derived mediator responsible, at least partly, for reprograming macrophage towards a reparative phenotype. In vivo, CCN2 expression was markedly elevated in Nlrx1KO infarcted hearts. Moreover, exogenous CCN2 partially mediated macrophage transition towards a reparative phenotype. ConclusionsCD9+ IL1rn+ macrophages modulated by Nlrx1 deficient cardiomyocytes-derived CCN2, is a novel subset of reparative macrophages contributing to infarct healing. Inhibition of myocardial Nlrx1 and/or activation of CCN2 to boost CD9+ IL1rn+ reparative macrophages may represent new therapeutics for infarct healing following ischemic injury.

immunology↗

bioRxiv2023

Syndecan-1 and thrombomodulin are early biomarkers for development of endotheliopathy in trauma and hemorrhagic shock

The causes of endotheliopathy are multifactorial and trauma dependent, and the temporal mechanistic link that it has with acute traumatic coagulopathy (ATC) has yet to be fully determined. Therefore, we sought to define early characteristics and markers of endotheliopathy in two rat models, a time-course of acute lethal hemorrhage shock and polytrauma with hemorrhagic shock, to answer the following questions: (1) how soon can elevated biomarkers of endotheliopathy be detected in non-survivable (decompensated) hemorrhagic shock; (2) does extended hemorrhage time and accumulated hemorrhage impact biomarker levels; and (3) does the addition of polytrauma contribute to the further elevation of said biomarkers? In this study, we delineated a significant, acute elevation in end plasma levels of syndecan-1, thrombomodulin, and heparan sulfate, whose shedding patterns are a function of time as well as total hemorrhage volume vs. the addition of polytrauma. Additionally, we found that correlation of syndecan-1 and thrombomodulin to lactate levels and prothrombin times at trauma end revealed a potential for these markers to acutely predict downstream consequences of these trauma indications. Our results are of great relevance to the continued effort towards the identification and characterization of vascular dysfunction for early interventions in combat casualty care.

cell biology↗

bioRxiv2023

Improving mRNA vaccine safety and efficiency with cationized lipid nanoparticle formula

The widespread use of Covid-19 mRNA vaccines has highlighted the need to address rare but concerning side effects. Systemic off-target gene expression has been identified as a primary cause of acute adverse reactions and side effects associated with nucleoside-modified mRNA vaccines. In this study, we incorporated the permanent cationic lipid Dotap component into the mRNA-LNP formula associated with the FDA-approved mRNA vaccine Comirnaty to create a novel positively charged LNP carrier for mRNA vaccine delivery. Using the optimized LNP formula to prepare SARS-Cov-2 Spike mRNA vaccines for immunogenicity testing, Balb/c mice exhibited improved immunogenicity kinetics with initial antibody titers being lower but showing a continuous upward trend, ultimately reaching levels comparable to those of control mRNA vaccines 8 weeks after boost immunization. The mRNA vaccines encapsulated in the modified LNPs have demonstrated a superior safety profile in respect to systemic delivery of LNP constituents, off-target gene expression, and the systemic pro-inflammatory stimulation. Consequently, it may represent a safer alternative of conventional mRNA-LNP vaccines.

synthetic biology↗

bioRxiv2023

Supervised learning of high-confidence phenotypic subpopulations from single-cell data

Accurately identifying phenotype-relevant cell subsets from heterogeneous cell populations is crucial for delineating the underlying mechanisms driving biological or clinical phenotypes. Here, by deploying a learning with rejection strategy, we developed a novel supervised learning framework called PENCIL to identify subpopulations associated with categorical or continuous phenotypes from single-cell data. By embedding a feature selection function into this flexible framework, for the first time, we were able to select informative features and identify cell subpopulations simultaneously, which enables the accurate identification of phenotypic subpopulations otherwise missed by methods incapable of concurrent gene selection. Furthermore, the regression mode of PENCIL presents a novel ability for supervised phenotypic trajectory learning of subpopulations from single-cell data. We conducted comprehensive simulations to evaluate PENCILs versatility in simultaneous gene selection, subpopulation identification and phenotypic trajectory prediction. PENCIL is fast and scalable to analyze 1 million cells within 1 hour. Using the classification mode, PENCIL detected T-cell subpopulations associated with melanoma immunotherapy outcomes. Moreover, when applied to scRNA-seq of a mantle cell lymphoma patient with drug treatment across multiple time points, the regression mode of PENCIL revealed a transcriptional treatment response trajectory. Collectively, our work introduces a scalable and flexible infrastructure to accurately identify phenotype-associated subpopulations from single-cell data.

bioinformatics↗

bioRxiv2023

Elevated ENO2 Disrupts VSMCs Homeostasis Facilitating the Development of Aortic Dissection

OBJECTIVEAortic dissection (AD) is a dangerous cardiovascular disease. However, its regulatory mechanism remains poorly understood. Autophagy is an important pathway for maintaining cellular homeostasis. Recent studies have shown that glycolysis and autophagy are essential for the development of AD. Elevated glycolysis can promote cells autophagy, but the relationship between the two is unclear. Enolase 2 (ENO2) is a glycolytic enzyme. Here, we investigated whether ENO2 can regulate autophagy in vascular smooth muscle cells (VSMCs) involved in the progression of AD. APPROACH AND RESULTSThe levels of ENO2 and autophagy-related proteins in aortic tissues from AD patients were identified by qRT-PCR, Western blot and IHC. We found that autophagosome clearance was impaired in aortic tissues and positively correlated with elevated ENO2 expression. Furthermore, aortic application of smooth muscle-specific adeno-associated virus (AAV) inhibiting ENO2 expression attenuated the development of AD in mice. in vitro experiments, downregulation of ENO2 partially restored PDGF-BB-induced impairment of autophagic flux, as evidenced by reduced expression of Beclin-1, SQSTM1, LC3BII/I and increased levels of LAMP2 in human aortic vascular smooth muscle cells (HAVSMCs). Similarly, increased levels of ENO2 exacerbated the autophagic dysfunction in HAVSMCs. Mechanistically, ENO2 may block autophagic flux through the ENO2-GAP43-ATF4 pathway and disrupt cellular homeostasis. CONCLUSIONSOur data reveal a perturbing role of ENO2 in the homeostasis of VSMCs, suggesting ENO2 as a potential target for intervention in AD.

molecular biology↗

bioRxiv2023

T-CLEARE: A Pilot Community-Driven Tissue-Clearing Protocol Repository

Selecting and implementing a tissue-clearing protocol is challenging. Established more than 100 years ago, tissue clearing is still a rapidly evolving field of research. There are currently many published protocols to choose from, and each performs better or worse across a range of key evaluation factors (e.g., speed, cost, tissue stability, fluorescence quenching). Additionally, tissue-clearing protocols are often optimized for specific experimental contexts, and applying an existing protocol to a new problem can require a lengthy period of adaptation by trial and error. Although the primary literature and review articles provide a useful starting point for optimization, there is growing recognition that many articles do not provide sufficient detail to replicate or reproduce experimental results. To help address this issue, we have developed a novel, freely available repository of tissue-clearing protocols named T-CLEARE (Tissue CLEAring protocol REpository; https://doryworkspace.org/doryviz). T-CLEARE incorporates community responses to an open survey designed to capture details not commonly found in the scientific literature, including modifications to published protocols required for specific use cases and instances when tissue-clearing protocols did not perform well (negative results). The goal of T-CLEARE is to provide a forum for the community to share evaluations and modifications of tissue-clearing protocols for various tissue types and potentially identify best-in-class methods for a given application.

bioinformatics↗

bioRxiv2023

Icariin prevents depression-like behaviors in chronic unpredictable mild stress-induced rats through Bax/cytoplasm C/caspase-3 axis to alleviate neuronal apoptosis

Major depressive disorder (MDD) affects approximately 16% of the global population. Our previous study has demonstrated that icariin (ICA) exhibits anti-depressant activity by increasing the expression of Brain Derived Neurotrophic Factor (BDNF) in a rat model of chronic unpredictable mild stress (CUMS). In this study, we investigated whether and how ICA can prevent CUMS-induced depression-like behaviors in rats by modulating hippocampus neuronal apoptosis. Forty male rats were randomly divided into control, CUMS, CUMS-fluoxetine (Flx) (10 mg/kg), and CUMS-ICA (20 mg/kg) groups. Behavior tests including sucrose preference test (SPT), open field test (OFT), elevated plus-maze (EPM), and forced swimming tests (FST) were performed. The Nissl staining and TUNNEL assay were used to determine neuronal apoptosis. Subsequently, expression of glucocorticoid receptor (GR), Bcl-2, cytochrome C, caspase-3 and Bax in the hippocampus were tested by western blot. Our results show that a chronic administration of ICA (20 mg/kg) can prevent CUMS-induced depressant-like behaviors in male model rats. Additionally, ICA significantly inhibited mitochondrial translocation of GR, reduced mitochondrial outer membrane permeabilization (MOMP) to suppress the release of cytochrome C, and then inhibit the activation of caspase-3. In conclusion, our research provides new evidence to understand the anti-depressant activity of ICA, which relates to its inhibition of neuronal apoptosis in hippocampus through mitochondrial apoptotic pathway.

molecular biology↗

bioRxiv2023

Requirement of GrgA for Chlamydia infectious progeny production

Hallmarks of the developmental cycle of the obligate intracellular pathogenic bacterium Chlamydia are the primary differentiation of the infectious elementary body (EB) cell type into the proliferative reticulate body (RB) and the secondary differentiation of RBs back into EBs. The detailed mechanisms regulating these transitions are unclear. In this study, we developed a novel strategy termed DOPE (dependence on plasmid-mediated expression) that allows for the knockdown of essential genes in Chlamydia. Importantly, we demonstrate that GrgA, a Chlamydia-specific transcription factor, is essential for the secondary differentiation of RBs into EBs. Our development of a conditional GrgA-deficient chlamydiae should prove valuable for future studies examining chlamydial growth, development, and pathogenicity. Furthermore, because EB formation is absolutely required for chlamydial dissemination within infected individuals, and for chlamydial transmission to new hosts, our maturation-defective chlamydiae system may serve as an attractive attenuated vaccine methodology for the prevention of chlamydial diseases.

microbiology↗

bioRxiv2023

Unfolded Protein Response Factor ATF6 Augments T Helper Cell Responses and Promotes Mixed Granulocytic Airway Inflammation

The unfolded protein response (UPR) is associated with the risk of asthma, including treatment- refractory severe asthma. Several recent studies demonstrated a pathogenic role of activating transcription factor 6 (ATF6 or ATF6), one of the essential arms of UPR, in airway structural cells. However, its role in T helper (TH) cells has not been well examined. In this study, we found that ATF6 was selectively induced by STAT6 and STAT3 in TH2 and TH17 cells, respectively. ATF6 upregulated UPR genes and promoted the differentiation and cytokine secretion of TH2 and TH17 cells. T cell-specific Atf6-deficiency impaired TH2 and TH17 responses in vitro and in vivo and attenuated mixed granulocytic experimental asthma. ATF6 inhibitor Ceapin A7 suppressed ATF6 downstream gene expression and TH cell cytokine expression in both murine and human memory CD4+ T cells. At the chronic stage of asthma, administration of Ceapin A7 lessened TH2 and TH17 responses in vivo, leading to alleviation of both airway neutrophilia and eosinophilia. Thus, our results demonstrate a critical role of ATF6 in TH2 and TH17 cell-driven mixed granulocytic airway disease, suggesting a novel option to combat steroid-resistant mixed and even T2-low endotypes of asthma by targeting ATF6.

immunology↗

bioRxiv2023

Excessive apoptosis of naïve T cells resulting hyperactivation as a cause of mammalian aging

In mammals, the most remarkable T cell variations with aging are the shrinking of naive T cell pool and enlargement of memory T cell pool, which are partially caused by thymic involution. However, it remains an enigma whether these T-cell-related changes are consequences or causes of mammalian aging. In this study, we find that the T-cell specific Rip1 KO mice present similar age-related T cell changes and exhibit signs of accelerated aging, including inflammation, multiple age-related diseases and a shorter lifespan. Mechanistically, T cells lacking RIP1 displayed excessive apoptosis, leading to T cell compensatory proliferation, hyperactivation, increased inflammation, and ultimately premature death. Consistent with this, blocking apoptosis by co-deletion of Fadd in Rip1 deficient T cells significantly recovered the lymphopenia and imbalance between naive and memory T cell, substantially restored ageing-related phenotypes, and prolonged life span in T-cell specific Rip1 KO mice. These results suggest that changes in T cells play a causal role in mammalian aging. Therefore, replenishing or blocking apoptosis of naive T cells could offer new therapeutic approaches for aging and age-related diseases.

immunology↗

bioRxiv2023

High immigration rates critical for establishing emigration-driven diversity in microbial communities

Unraveling the mechanisms governing the diversity of ecological communities is a central goal in ecology. While microbial dispersal (including the emigration and immigration process) constitutes an important ecological process, the coupling effects of dispersal and microbial competition in microbial diversity are poorly understood. Here, we investigated how microbial dispersal affects the diversity of microbial communities in the presence of inter-species competition, using a generalized Lotka-Volterra model in combination with experimental investigations. Our model shows that emigration reduces the diversity induced by immigration at low immigration rates. We surprisingly find that it increases the diversity of the community when the immigration rates cross a defined threshold, which we identified as Ineutral. We also found that at high immigration rates, emigration weakens the relative abundance of fast-growing species, and thus enhances the mass effect and increases the diversity. We experimentally confirmed this finding using cocultures of 20 bacterial strains isolated from the soil. Our model further showed that Ineutral exists over a wide range of species pool sizes, growth rates, and interspecies interactions, and decreases with the increasing of species pool size, growth rate, and interspecies interaction. Our work deepens the understanding of the effects of dispersal on diversity of natural communities.

ecology↗