Search bioRxiv⌕ Search

Biology subjects

Peng, Y.

Publications and source records attributed to Peng, Y..

At least 109 records · Page 6Linked to original sources

Critical assessment of missense variant effect predictors on disease-relevant variant data

Regular, systematic, and independent assessment of computational tools used to predict the pathogenicity of missense variants is necessary to evaluate their clinical and research utility and suggest directions for future improvement. Here, as part of the sixth edition of the Critical Assessment of Genome Interpretation (CAGI) challenge, we assess missense variant effect predictors (or variant impact predictors) on an evaluation dataset of rare missense variants from disease-relevant databases. Our assessment evaluates predictors submitted to the CAGI6 Annotate-All-Missense challenge, predictors commonly used by the clinical genetics community, and recently developed deep learning methods for variant effect prediction. To explore a variety of settings that are relevant for different clinical and research applications, we assess performance within different subsets of the evaluation data and within high-specificity and high-sensitivity regimes. We find strong performance of many predictors across multiple settings. Meta-predictors tend to outperform their constituent individual predictors; however, several individual predictors have performance similar to that of commonly used meta-predictors. The relative performance of predictors differs in high-specificity and high-sensitivity regimes, suggesting that different methods may be best suited to different use cases. We also characterize two potential sources of bias. Predictors that incorporate allele frequency as a predictive feature tend to have reduced performance when distinguishing pathogenic variants from very rare benign variants, and predictors supervised on pathogenicity labels from curated variant databases often learn label imbalances within genes. Overall, we find notable advances over the oldest and most cited missense variant effect predictors and continued improvements among the most recently developed tools, and the CAGI Annotate-All-Missense challenge (also termed the Missense Marathon) will continue to assess state-of-the-art methods as the field progresses. Together, our results help illuminate the current clinical and research utility of missense variant effect predictors and identify potential areas for future development.

genetics↗

Amygdala engages non-emotional multi-item working memory maintenance through amygdala-hippocampus interaction

Retaining information in working memory (WM) is an active process that requires neural activity within and between regions. The human amygdala (AMY) and hippocampus (HPC) are known to play crucial roles in WM processing. Although electrophysiological studies have revealed that the HPC supports multi-item maintenance in a load-dependent manner, the characteristics of the AMY and the circuit-level mechanisms underlying AMY-HPC interactions remain largely unexplored. To address this knowledge gap, intracranial EEG recordings from the AMY and HPC in nine epileptic patients were employed to evaluate intraregional neural representations and interregional communications during maintenance under different non-emotional WM loads. High load enhanced low-frequency power and intraregional theta-gamma phase-amplitude coupling (PAC) in the AMY and HPC. At the network level, a high load elicited an increase in the strength of the HPC theta phase modulation, which entrains the AMY gamma amplitude. Furthermore, a high load increased AMY-anterior HPC (aHPC) theta phase synchrony and directional connectivity strength from the aHPC to the AMY. Conversely, posterior HPC (pHPC)-AMY synchrony was not affected by load variations. Overall, these findings highlight the importance of the AMY in non-emotional WM tasks and provide new insights into the neurophysiological basis of AMY-HPC interactions during WM maintenance.

neuroscience↗

The genomic and epigenomic dynamics of hemizygous genes across crops with contrasting mating systems

Hemizygous genes, which present on only one of the two homologous chromosomes of diploid organisms, have been mainly studied in the context of sex chromosomes and sex-linked genes. However, structural variants (SVs), such as a deletion/insertion of one allele, can lead to hemizygous genes, a phenomenon largely unexplored in plants. Here, we investigated the genomic and epigenomic landscapes of hemizygous genes across 22 genomes with varying propagation histories: eleven clonal lineages, seven outcrossed samples and four inbred and putatively homozygous genomes. We identified SVs leading to genic hemizygosity. As expected, very few genes (0.01%-1.2%) were hemizygous in the homozygous genomes, representing negative controls. Hemizygosity was appreciable among outcrossed lineages, averaging 8.7% of genes, but consistently elevated for the clonal samples at 13.8% genes, likely reflecting heterozygous SVs accumulation during clonal propagation. Compared to diploid genes, hemizygous genes were more often situated in centromeric than telomeric regions and underlying weaker purifying selection. They also had reduced levels of expression, averaging [~]20% of the expression levels of diploid genes, violating the evolutionary model of dosage compensation. We also detected higher DNA methylation levels, in hemizygous genes and transposable elements, which may contribute to the reduced expression of hemizygous genes. Finally, expression profiles showed that hemizygous genes were more specifically expressed in contexts related to fruit development, organ differentiation and stress responses. Overall, hemizygous genes accumulate in clonally propagated lineages and display distinct genetic, and epigenetic features compared to diploid genes, shedding new insights on genetic studies and breeding programs of clonal crops.

plant biology↗

Grifola frondosa polysaccharide Ameliorates Inflammation and Insulin Resistance by Regulating Macrophage Polarization of liver in Type 2 Diabetes Mellitus Rats

Type 2 diabetes mellitus (T2DM) is a common metabolic disease characterized by a lack of insulin secretion, insulin resistance (IR), and hyperglycemia. Given its high prevalence and multifarious complications, diabetes is globally ranked as the third leading cause of mortality. It is critical to discover efficient medication substitutes in order to lessen the drawbacks and adverse effects of traditional diabetes medication therapy. Previous studies have shown that Grifola frondosa polysaccharide (GFP) have the positive effects in regulating blood glucose and insulin resistance, but the understanding of its regulatory mechanism is still limited. Therefore, this study aimed to investigate the effects of GFP on liver inflammation induced by a high-fat diet (HFD) combined with streptozotocin (STZ) in type 2 diabetic rats and to explore its possible mechanisms. The results showed that GFP intervention reduced weight loss and hyperglycemia symptoms, as well as lowered FINS, HOMA-IR, IPGTT-AUC, and IPITT-AUC to different degrees in T2DM rats. At the same time, after GFP intervention, the secretion level of inflammatory factors (TNF-, IL-1{beta}, MCP-1) was down-regulated and the secretion level of anti-inflammatory factor (IL-10) was up-regulated in the liver tissue of T2DM rats. Furthermore, GFP reduced macrophage infiltration in liver tissue, inhibited macrophage M1-type polarization, and promoted M2-type polarization. These results suggest that GFP intervention could attenuate the hepatic inflammatory response in T2DM rats; possible mechanisms for this effect include hepatic macrophage infiltration and M1/M2 polarization. Summary statementThis study revealed the improvement effect of GFP on hepatic inflammation and insulin resistance in T2DM rats and to explore the possible key roles of hepatic macrophages and their potential mechanisms.

immunology↗

Enzymes enabling the biosynthesis of various C20 polyunsaturated fatty acids in a sea urchin Hemicentrotus pulcherrimus

Sea urchins, integral to marine ecosystems and valued as a delicacy in Asia and Europe, contain physiologically important long-chain (>C20) polyunsaturated fatty acids (PUFA) in their gonads, including arachidonic acid (ARA, 20:4n-6), eicosapentaenoic acid (EPA, 20:5n-3), and unusual non-methylene interrupted fatty acids (NMI-FA) such as 20:2{Delta}5,11. Although these fatty acids may partially be derived from their diet, such as macroalgae, the present study on Hemicentrotus pulcherrimus has uncovered multiple genes encoding enzymes involved in LC-PUFA biosynthesis. Specifically, three fatty acid desaturases (FadsA, FadsC1 and FadsC2) and thirteen elongation of very-long chain fatty acids proteins (Elovl-like, Elovl1/7-like, Elovl2/5-like, Elovl4-like, Elovl8-like, Elovl6-like A to H) were identified in their genome and transcriptomes. Functional analysis showed that FadsA and FadsC2 function as a {Delta}5 desaturase and a {Delta}8 desaturase, respectively, enabling the conversion of 18:2n-6 and 18:3n-3 into ARA and EPA, respectively, along with Elovl, particularly Elovl6-like C. Elovl6-like C demonstrates elongase activity towards both C18 PUFA and monounsaturated fatty acids (MUFA). Consequently, FadsA and Elovl6-like C enable to synthesise several NMI-FA, including 20:2{Delta}5,11 and 20:3{Delta}5,11,14, from C18 precursors. This indicates that H. pulcherrimus can endogenously synthesise a wide variety of C20 PUFA and NMI-FA, highlighting active biosynthesis pathways within sea urchins.

biochemistry↗

Spatiotemporal cerebral blood flow dynamics underlies emergence of the limbic-sensorimotor-association cortical gradient in human infancy

Infant cerebral blood flow (CBF) delivers nutrients and oxygen to fulfill brain energy consumption requirements for the fastest period of postnatal brain development across lifespan. However, organizing principle of whole-brain CBF dynamics during infancy remains obscure. Leveraging a unique cohort of 100+ infants with high-resolution arterial spin labeled MRI, we found the emergence of the cortical hierarchy revealed by highest-resolution infant CBF maps available to date. Infant CBF across cortical regions increased in a biphasic pattern with initial rapid and sequentially slower rate, with break-point ages increasing along the limbic-sensorimotor-association cortical gradient. Increases in CBF in sensorimotor cortices were associated with enhanced language and motor skills, and frontoparietal association cortices for cognitive skills. The study discovered emergence of the hierarchical limbic-sensorimotor-association cortical gradient in infancy, and offers standardized reference of infant brain CBF and insight into the physiological basis of cortical specialization and real-world infant developmental functioning.

neuroscience↗

Single-cell profiling reveals the intratumor heterogeneity and immunosuppressive microenvironment in cervical adenocarcinoma

BackgroundCervical adenocarcinoma (ADC) is more aggressive compared to other types of cervical cancer (CC), such as squamous cell carcinoma (SCC). The tumor immune microenvironment (TIME) and tumor heterogeneity are recognized as pivotal factors in cancer progression and therapy. However, the disparities in TIME and heterogeneity between ADC and SCC are poorly understood. MethodsWe performed single-cell RNA sequencing on 11 samples of ADC tumor tissues, with other 4 SCC samples served as controls. The immunochemistry and multiplexed immunofluorescence were conducted to validate our findings. ResultsCompared to SCC, ADC exhibited unique enrichments in several sub-clusters of epithelial cells with elevated stemness and hyper-malignant features, including the Epi_10_CYSTM1 cluster. ADC displayed a highly immunosuppressive environment characterized by the enrichment of regulatory T cells (Tregs) and tumor-promoting neutrophils. The Epi_10_CYSTM1 cluster recruits Tregs via ALCAM-CD6 signaling, while Tregs reciprocally induce stemness in the Epi_10_CYSTM1 cluster through TGF{beta} signaling. Importantly, our study revealed that the Epi_10_CYSTM1 cluster could serve as a valuable predictor of lymph node metastasis for CC patients. ConclusionsThis study highlights the significance of ADC-specific cell clusters in establishing a highly immunosuppressive microenvironment, ultimately contributing to the heightened aggressiveness and poorer prognosis of ADC compared to SCC.

cancer biology↗

The protective roles of Eugenol on type 1 diabetes mellitus through NRF2 mediated oxidative stress pathway

Type 1 diabetes mellitus (T1DM), known as insulin-dependent diabetes mellitus, is characterized by persistent hyperglycemia resulting from damage to the pancreatic {beta} cells and an absolute deficiency of insulin, leading to multi-organ involvement and a poor prognosis. The progression of T1DM is significantly influenced by oxidative stress and apoptosis. The natural compound eugenol (EUG) possesses anti-inflammatory, anti-oxidant, and anti-apoptotic properties. However, the potential effects of EUG on T1DM had not been investigated. In this study, we established the streptozotocin (STZ)-induced T1DM mouse model in vivo and STZ-induced pancreatic {beta} cell MIN6 cell model in vitro to investigate the protective effects of EUG on T1DM, and tried to elucidate its potential mechanism. Our findings demonstrated that the intervention of EUG could effectively induce the activation of nuclear factor E2-related factor 2 (NRF2), leading to an up-regulation in the expressions of downstream proteins NQO-1 and HO-1, which are regulated by NRF2. Moreover, this intervention exhibited a significant amelioration in pancreatic {beta} cell damage associated with T1DM, accompanied by an elevation in insulin secretion and a reduction in the expression levels of apoptosis and oxidative stress related markers. Furthermore, ML385, an NRF2 inhibitor, reversed these effects of EUG. The present study suggested that EUG exerted protective effects on pancreatic {beta} cells in T1DM by attenuating apoptosis and oxidative stress through the activation of the NRF2 signaling pathway. Consequently, EUG holds great promise as a potential therapeutic candidate for T1DM.

pharmacology and toxicology↗

Chronic alcohol exposure induces cerebral microbleeds by TGF-β1/Smad signaling pathway mediated remodeling of cerebral small vessels

BackgroundLong-term heavy drinking is a major risk factor for cerebral microbleeds(CMBs), which are increasingly gaining attention as a pathological phenotype of cerebral small vessel diseases(CSVD). Under pathological conditions, remodeling of the extracellular matrix(ECM) on the walls of small vessels causes disarray in the structure and function of these vessels, leading to cerebral small vessel sclerosis and consequent rupture and bleeding. This can result in cognitive and emotional disorders, abnormal gait and increased risk of falling. However, the mechanisms underlying how long-term alcohol consumption leads to CMBs and decline in motor function remain unknown. MethodsWe constructed a chronic alcohol exposure mouse model and measured the deposition of ECMs on the small vessels in motor-related brain regions. The presence of microbleeds was confirmed through Prussian blue staining and Magnetic Resonance Imaging. We also extracted primary cerebral microvascular smooth muscle cells (CMVSMCs) from the newborn mice and explored the effects of alcohol on the phenotypic transformation and substance synthesis function. Additionally, we conducted interventional experiments on the cell and animal models with an anti-fibrotic drugs Pirfenidone(PFD). ResultsWe found that mice with long-term alcohol exposure showed decreased motor function. In their motor-related brain regions, such as the motor cortex(MC), thalamus/basal ganglia(Tha/BG), and cerebellum(CB), we observed microbleeds. On the small vessels in these areas, we detected excessive deposited ECM proteins. In vitro experiments with primary CMVSMCs revealed that after alcohol treatment, the cells underwent a transformation into fibroblast-like phenotypes, and excessive production of the aforementioned ECM proteins, which is regulated by upstream TGF{beta}1/Smad signaling pathway. Additionally, PFD applied on cell and animal models could reverse the above processes to some extent. ConclusionsOur study found that the remodeling of ECM accompanied by activation of TGF-{beta}1/Smad signaling pathway may be involved in alcohol-induced CMBs. It could be a potential therapeutic target for CMBs or CSVD.

molecular biology↗

Genome-wide Nucleosome Positioning and Associated Features uncovered with Interpretable Deep Residual Networks

Nucleosomes represent elementary building units of eukaryotic chromosomes and consist of DNA wrapped around a histone octamer flanked by linker DNA segments. Nucleosomes are central in epigenetic pathways and their genomic positioning is associated with regulation of gene expression, DNA replication, DNA methylation and DNA repair, among other functions. Building on prior discoveries, that DNA sequences noticeably affect nucleosome positioning, our objective is to identify nucleosome positions and related features across entire genome. Here we introduce an interpretable framework based on the concepts of deep residual networks (NuPose). Trained on high-coverage human experimental MNase-seq data, NuPose is able to learn sequence and structural patterns and their dependencies associated with nucleosome organization in human genome. NuPoSe can be used to identify nucleosomal regions, not covered by experiments, and be applied to unseen data from different organisms and cell types. Our findings point to 43 informative DNA sequence features, most of them constitute tri-nucleotides, di-nucleotides and one tetra-nucleotide. Most features are significantly associated with the structural characteristics, namely, periodicity of nucleosomal DNA and its location with respect to a histone octamer. Importantly, we show that linker DNA features contribute [~]10% to the quality of the prediction model, which together with comprehensive training sets, deep-learning architecture and feature selection may explain the advanced performance of NuPose of 80-89% accuracy.

bioinformatics↗

A natural language processing system for the efficient extraction of cell markers

1.BackgroundIn the last few years, single-cell RNA sequencing (scRNA-seq) has been widely used in various species and tissues. The construction of the cellular landscape for a given species or tissue requires precise annotation of cell types, which relies on the quality and completeness of existing empirical knowledge or manually curated cell marker databases. The natural language processing (NLP) technique is a potent tool in text mining that enables the rapid extraction of entities of interest and relationships between them by parsing the syntax structure. Methods and resultsWe developed MarkerGeneBERT, an NLP-based system designed to automatically extract information about species, tissues, cell types and cell marker genes by parsing the full texts of the literature from single-cell sequencing studies. As a result, 8873 cell markers of 1733 cell types in 435 human tissues/subtissues and 9064 cell markers of 1832 cell types in 492 mouse tissues/subtissues were collected from 3987 single-cell sequencing-related studies. By comparison with the marker genes of existing manual curated cell marker databases, our method achieved 76% completeness and 75% accuracy. Furthermore, within the same literature, we found 89 cell types and 183 marker genes for which the cell marker database was not available. Finally, we annotated brain tissue single-cell sequencing data directly using the compiled list of brain tissue marker genes from our software, and the results were consistent with those of the original studies. Taken together, the results of this study illustrate for the first time how systematic application of NLP-based methods could expedite and enhance the annotation and interpretation of scRNA-seq data.

bioinformatics↗

Phylogenetically and structurally diverse reductive dehalogenases link biogeochemical cycles in deep-sea cold seeps

Reductive dehalogenation is crucial for halogen cycling and environmental remediation, yet its ecological role is not completely understood, especially in deep-sea environments. To address this gap, we investigated the diversity of reductive dehalogenases (RDases) and ecophysiology of organohalide reducers in deep-sea cold seeps, which are environments rich in halogenated compounds. Through genome- resolved metagenomic analysis of 165 global cold seep sediment samples, we identified four types of RDases, namely prototypical respiratory, transmembrane respiratory, and cytosolic RDases, and one novel clade. Cold seeps were found to harbor a higher abundance of these RDase genes compared to other marine sediments, establishing them as unique hotspots for microbial reductive dehalogenation activity. These RDases are encoded by a wide range of microorganisms across four archaeal and 36 bacterial phyla, significantly expanding the known diversity of organohalide reducers. Halogen geochemistry, laboratory incubations with various halogenated compounds, metatranscriptomic data, and metabolomic profiling confirmed the presence of organohalides at concentrations of up to 18 mg/g in these sediments and demonstrated their active microbial reduction. This process is tightly linked to other biogeochemical cycles, including carbon, hydrogen, nitrogen, sulfur, and trace elements. RDases from cold seeps have diverse N-terminal structures across different gene groups, and reductive dehalogenase genes in these environments are mostly functionally constrained and conserved. These findings collectively suggest that reductive dehalogenation is a central process in deep-sea environments, mediated by a diverse array of microbes and novel enzymes.

microbiology↗

Monocyte-derived fibrocytes contribute to nucleus pulposus fibrosis and intervertebral disc degeneration

Fibrotic remodeling of nucleus pulposus (NP) leads to structural and mechanical anomalies of intervertebral discs that prone to degeneration, leading to low back pain incidence and disability. Emergence of fibroblastic cells in disc degeneration has been reported, yet their nature and origin remain elusive. In this study, we performed an integrative analysis of multiple single-cell RNA sequencing datasets to interrogate the cellular heterogeneity and fibroblast-like entities in degenerative human NP specimens. We found that disc degeneration severity is associated with an enrichment of fibrocyte-like phenotype, characterized by CD45 and collagen I dual positivity, and expression of myofibroblast marker -smooth muscle actin. Refined clustering and classification distinguished the fibrocyte-like populations as subtypes in the NP cells - and immunocytes-clusters, expressing disc degeneration markers HTRA1 and ANGPTL4 and genes related to response to TGF-{beta}. In injury-induced mouse disc degeneration model, fibrocyte-like cells were found recruited into the NP undergoing fibrosis and adopted a myofibroblast phenotype. Depleting the fibrocyte-like cells in CD11b-DTR mice in which monocytic lineages were ablated by diphtheria toxin could markedly attenuate fibrous modeling and myofibroblast formation in the NP of the degenerative discs, and prevent disc height loss and histomorphological abnormalities. Marker analysis supports that disc degeneration progression is dependent on a function of CD45+COL1A1+ and SMA+ cells. Our findings reveal that fibrocyte-like cells play a pivotal role in NP fibrosis and may therefore be a target for modifying disc degeneration and promoting its repair.

physiology↗

A highly contiguous hexaploid wheat genome assembly facilitates analysis of 1RS translocation and mining of a new adult plant resistance locus to yellow rust disease

High-quality genome information is essential for efficiently deciphering and improving crop traits. Here we report a highly contiguous hexaploid genome assembly for the key wheat breeding parent Zhou8425B, an elite 1BL/1RS translocation line with durable adult plant resistance (APR) against rust diseases. By using HiFi and Hi-C sequencing reads, a 14.75 Gb genome assembly, with contig N50 and scaffold N50 values reaching 70.94 and 735.11 Mb, respectively, was developed. Comparison with 16 previously sequenced common wheat cultivars revealed unique chromosomal structural features in Zhou8425B. Notably, the 1RS translocation in Zhou8425B was apparently longer and carried more genes encoding AP2/ERF-ERF and B3 transcription factors relative to its counterpart in several genome sequenced 1BL/1RS varieties and rye lines. Aided by Zhou8425B genome assembly, a new APR locus (i.e., YrZH3B) against yellow rust (YR) disease was finely mapped to a 1 - 2 Mb interval on chromosome 3BS. Analysis with 212 Zhou8425B derivative varieties showed that pyramiding of YrZH3B with two other APR loci (YrZH22 and YrZH84) significantly decreased YR severity and enhanced grain yield, with triple combination (YrZH3B/YrZH22/YrZH84) having the highest effects. Our data demonstrate the high value of Zhou8425B assembly in studying wheat genome and agronomically important genes.

genomics↗

Comprehensive characterization of the integrin family across 32 cancer types

Integrin genes widely involve in tumorigenesis. Yet, a comprehensive characterization of integrin family and their interactome on the pan-cancer level is lacking. Here, we systematically dissect integrin family in nearly 10000 tumors across 32 cancer types. Globally, integrins represent a frequently altered and misexpressed pathway, with alteration and dysregulation overall being protumorigenic. Expression dysregulation, better than mutational landscape, of integrin family successfully identifies a subgroup of aggressive tumors demonstrating a high level of proliferation and stemness. We identify that several molecular mechanisms jointly regulate integrin expression in a context-dependent manner. For potential clinical usage, we construct a weighted score, integrinScore, to measure integrin signaling patterns in individual tumors. Remarkably, integrinScore consistently correlates with predefined molecular subtypes in multiple cancers, with integrinScore high tumors being more aggressive. Importantly, integrinScore is cancer-dependently and closely associated with proliferation, stemness, tumor microenvironment, metastasis, and immune signatures. IntegrinScore also predicts patients response to immunotherapy. By mining drug databases, we unravel an array of compounds that may serve as integrin signaling modulators. Finally, we build a user-friendly database to facilitate researchers to explore integrin-related knowledge. Collectively, we provide a comprehensive characterization of integrins across cancers, which offers gene- and cancer-specific rationales for developing integrin-targeted therapy.

bioinformatics↗

Integrative genomics reveals the polygenic basis of seedlessness in grapevine

Seedlessness is a crucial quality trait in table grape (Vitis vinifera L.) breeding. However, the development of seeds involved intricate regulations, while the polygenic basis of seed abortion remains unclear. Here, we combine comparative genomics, population genetics, quantitative genetics, and integrative genomics to unravel the evolution and polygenic basis of seedlessness in grapes. We generated four haplotype-resolved telomere-to-telomere (T2T) genomes for two seedless grape cultivars, Thompson Seedless (TS, syn. Sultania) and Black Monukka (BM). Comparative genomics identified a [~]4.25 Mb hemizygous inversion on Chr10 specific in seedless cultivars, with seedless-associated genes VvTT16 and VvSUS2 located at breakpoints. Population genomic analyses of 548 grapevine accessions revealed two distinct clusters of seedless cultivars, tracing the origin of the seedlessness trait back to Sultania. Introgression, rather than convergent selection, shaped the evolutionary history of seedlessness in grape improvement. Genome-wide association study (GWAS) analysis identified 110 quantitative trait loci (QTLs) associated with 634 candidate genes, including novel candidate genes, such as three 11S GLOBULIN SEED STORAGE PROTEIN and two CYTOCHROME P450 genes, and well-known genes like VviAGL11. Integrative genomic analyses resulted in 339 core candidate genes categorized into 13 groups related to seed development. Machine learning based genomic selection achieved a remarkable 99% precision in predicting grapevine seedlessness. Our findings highlight the polygenic nature of seedless and provide novel candidate genes for molecular genetics and an effective prediction for seedlessness in grape genomic breeding.

genetics↗

Single cell discovery of m6A RNA modifications in the hippocampus

N6-methyladenosine (m6A) is a prevalent and highly regulated RNA modification essential for RNA metabolism and normal brain function. It is particularly important in the hippocampus, where m6A is implicated in neurogenesis and learning. Although extensively studied, its presence in specific cell types remain poorly understood. We investigated m6A in the hippocampus at the single cell level, revealing a comprehensive landscape of m6A modifications within individual cells. Our data also identifies transcripts which have high m6A density and are associated with brain diseases. Our data suggests that m6A containing transcripts might be of particular importance for Camk2a neurons. Overall, this work provides new insights into the molecular mechanisms underlying hippocampal physiology and lays the foundation for future studies investigating the dynamic nature of m6A RNA methylation in the healthy and diseased brain.

neuroscience↗

Strengthening Bordetella pertussis genomic surveillance by direct sequencing of residual positive specimens

Whole-genome sequencing (WGS) of microbial pathogens recovered from patients with infectious disease facilitates high-resolution strain characterization and molecular epidemiology. However, increasing reliance on culture-independent methods to diagnose infectious diseases has resulted in few isolates available for WGS. Here we report a novel culture-independent approach to genome characterization of Bordetella pertussis, the causative agent of pertussis and a paradigm for insufficient genomic surveillance due to limited culture of clinical isolates. Sequencing libraries constructed directly from residual pertussis-positive diagnostic nasopharyngeal specimens were hybridized with biotinylated RNA "baits" targeting B. pertussis fragments within complex mixtures that contained high concentrations of host and microbial background DNA. Recovery of B. pertussis genome sequence data was evaluated with mock and pooled negative clinical specimens spiked with reducing concentrations of either purified DNA or inactivated cells. Targeted enrichment increased yield of B. pertussis sequencing reads up to 90% while simultaneously decreasing host reads to less than 10%. Filtered sequencing reads provided sufficient genome coverage to perform characterization via whole-genome single nucleotide polymorphisms (wgSNP) and whole-genome multilocus sequencing typing (wgMLST). Moreover, these data were concordant with sequenced isolates recovered from the same specimens such that phylogenetic reconstructions from either consistently clustered the same putatively linked cases. The optimized protocol is suitable for nasopharyngeal specimens with IS481 Ct < 35 and > 10 ng DNA. Routine implementation of these methods could strengthen surveillance and study of pertussis resurgence by capturing additional cases with genomic characterization.

genomics↗