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Flores, J.

Publications and source records attributed to Flores, J..

18 recordsLinked to original sources

Interactive Data Integrator for Uniform Data Processing in the MorPhiC Program

We present an interactive Data Integrator to facilitate uniform data processing and integration with datasets generated by the NIH funded MorPhiC (Molecular Phenotypes of Null Alleles in Cells) program. In the dataset identification step, users can select published bulk RNA sequencing (RNA-seq) datasets generated by the MorPhiC program, specify external datasets from the Gene Expression Omnibus (GEO) repository, or upload raw RNA-seq data. Subsequently, users can select a subset of samples and indicate experimental design by assigning groups to samples. External data will then be processed using the MorPhiC approved bulk RNA-seq analytical pipeline, and differential expression will be inferred. Users also have the option to download the uniformly processed counts table.

bioinformatics↗

The DNA Legacy of Thomas Jefferson

Allegations that Thomas Jefferson fathered the children of the enslaved Sally Hemings emerged in the context of U.S. presidential politics in the late 1700s and early 1800s and entailed strongly contested denials and affirmations by family members, biographers, and historians ever since. Previous analysis of Y chromosome markers in contemporary members of the Jefferson and Hemings patrilines was consistent with the paternity hypothesis but rejected by those who pointed out that, absent Jefferson DNA and its direct comparison to the DNA of possible descendants, other Jefferson males could have fathered Sally Hemings children. In this study, we developed an innovative technique to recover DNA from multiple rootless hair samples in a museum collection whose provenance, mitochondrial genomes, Y chromosome markers, and identity to each other indicate that these hairs and the DNA from them are from Thomas Jefferson. Using these DNA data, we find clear evidence of Thomas Jefferson ancestry in descendants of both his wife Martha Wayles Jefferson and Sally Hemings. We measured the amount of identical-by-descent DNA shared between Thomas Jefferson and his known and putative descendants. We find that the amount of shared Jefferson DNA is more likely under the model of direct Thomas Jefferson paternity than other proposed scenarios.

genomics↗

Recommendations for the ethical and accurate use of population descriptors: a trainee-led survey of early-career researchers

Despite the importance of population descriptors in human genomics research, many scientists struggle to translate evolving ethical guidelines into their computational workflows. To characterize this gap between recommendations and implementation, we conducted a mixed-methods survey of early-career researchers to assess how they understand and implement the landmark 2023 NASEM report on the use of population descriptors in human genetics research. We show that while exposure to the report fosters ethical awareness, fundamental misconceptions about race and ancestry persist across academic disciplines, and trainees face structural bottlenecks, including legacy data constraints and a lack of technical confidence. To address this gap, we offer actionable, stakeholder-specific recommendations across the research lifecycle ranging from decision-support tools to "bring-your-own-data" workshops to leadership from academic journals, scientific societies, and trainee mentors. Ultimately, we argue that to promote scientific rigor and reduce bias in genetic discoveries, the scientific ecosystem must invest in the infrastructure necessary to empower the next generation of researchers.

genetics↗

Senataxin loss induces cGAS–STING-mediated mitochondrial dysfunction

Ataxia with oculomotor apraxia type 2 (AOA2) is a rare neurodegenerative disease caused by loss-of-function mutations in Senataxin, which encodes an RNA:DNA helicase. Many studies on Senataxin loss focus on its putative roles in regulating transcription and RNA transcript localization. However, several phenotypes remain underexplored, including metabolic dysregulation associated with ataxias. Using Senataxin-deficient mouse cells, we observed increased nuclear and genomic instability, as well as innate immune activation via the cGAS-STING axis. We also observed elevated ROS levels, decreased mitochondrial function, and hyperfused mitochondria. Importantly, mitochondrial dysfunction depends on cGAS/STING activity, indicating that the two phenotypes are functionally connected. Senataxin-deficient mice and AOA2 patient cells similarly exhibit spontaneous innate immune activation, and AOA2 patient cells also show decreased mitochondrial function. Our work identifies a previously unseen phenotype for AOA2 in which loss of Senataxin results in mitochondrial dysfunction promoted by cGAS and STING. SummaryThis study demonstrates a previously unidentified phenotype in AOA2 and Senataxin research in which cGAS-STING promotes mitochondrial dysregulation in Setx-/- MEFs. Further, these innate immune activation and mitochondrial dysregulated phenotypes are recapitulated in AOA2 patient cells.

Cell Biology↗

Correcting spatial transcriptomics data affected by a prevalent transcript leakage problem across platforms, species, and tissues

Spatial transcriptomics has been widely applied to study the spatial distribution of cell types, cell states, and specific gene expression in tissue samples. However, we show that there is a prevalent transcript leakage problem in spatial transcriptomics data, where transcripts expressed by a cell diffuse to its neighborhood and are recurrently detected in the nearby cells. By analyzing published data sets, we show that this problem is general across data produced from different tissues and different species using different imaging-based and sequencing-based spatial transcriptomics platforms. It affects both upstream tasks such as expression quantification as well as downstream tasks such as cell-type annotation and detection of spatially-dependent gene expression. To tackle the transcript leakage problem, we propose a reference-free Bayesian model-based method, DeLeakage, which cleans up the data much more effectively than existing denoising methods. DeLeakage also improves cell-type annotation and avoids false detection of spatially dependent expression.

bioinformatics↗

PRDM3 and PRDM16 define cranial neural crest cell states in zebrafish development

Cartilage and bone that comprise craniofacial structures as well as neurons and glia of the peripheral nervous system are derived from a multipotent population of cranial neural crest cells, that respond to both cell intrinsic and extrinsic cues to differentiate into precise cell states. Both a genetic and epigenetic regulatory network are required for each step in the differentiation process, involving transcription factors, histone modifiers and chromatin remodelers. Here, we examined the direct transcriptional targets of two histone methyltransferases, Prdm3 and Prdm16 in zebrafish neural crest cells at 48 hours post fertilization in zebrafish. Using CUT&RUN, we examined both direct DNA binding and nucleosome association. At this stage of development, CUT&RUN fragment size analysis indicated that Prdm3 and Prdm16 are largely associated with nucleosomes. We further analyzed these nucleosome peak sets to identify 6 clusters where differential binding of Prdm3 and Prdm16 and differential enrichment of gene ontology terms for target genes was observed. We validated gene expression in each cluster by in situ hybridization chain reaction (HCR) at 48 hpf demonstrating that prdm3 and prdm16 mutants exhibit corresponding changes in gene expression of the putative gene targets identified. Finally, we performed CUT&RUN-qPCR in prdm3 and prdm16 mutant zebrafish embryos and demonstrated reduced binding at putative target loci. Together these data suggest that Prdm3 and Prdm16 regulate their transcriptional targets primarily by binding nucleosomes around their putative target loci to control downstream gene expression. HighlightsPrdm3 and Prdm16 associate with nucleosomes for regulation of gene expression Gene targets are altered in prdm3 and prdm16 mutant zebrafish Reduced binding is observed in respective mutants

developmental biology↗

Subclonal Complete Loss of CDKN1B as a Common Genomic Alteration in Prostate Cancer: Associations with Race and Prostate Cancer Outcomes

BackgroundHomozygous biallelic inactivation of CDKN1B is thought to be rare in cancer. Herein we evaluate the prevalence of intratumoral (subclonal) complete p27 protein loss (IPPL) in primary prostate cancer. Experimental DesignWe used immunohistochemistry (IHC) for p27 in a large cohort of whole tissue sections from radical prostatectomy (n=412) and metastases from self-identified African American (AA) and European American (EA) individuals. IPPL was evaluated alongside CDKN1B mRNA in-situ hybridization and next generation sequencing of laser captured cancer regions. Cox proportional hazards analyses assessed the association of IPPL with biochemical recurrence and development of metastases after radical prostatectomy. ResultsIPPL was detected in 18.1% of AA versus 12.2% of EA cases and was tightly correlated with CDKN1B mRNA loss and biallelic genomic loss. IPPL was associated with [≥]pT3 pathologic stage and pN1 disease, however these associations were only significant among AA participants. IPPL was further associated in both univariate and multivariate analyses with the development of biochemical recurrence and metastasis after primary treatment, specifically in AA individuals. The prevalence of p27 genomic alterations in metastatic disease is higher than that of primary prostate cancer in publicly available datasets as well as our analysis of autopsy cases via IHC, indicating that complete p27 loss may be selected for in metastatic disease. ConclusionsSubclonal biallelic loss of CDKN1B resulting in complete p27 protein loss is one of the most commonly occurring biallelic tumor suppressor genomic alterations in primary prostate cancer, and could contribute to worse prostate cancer outcomes, specifically in AA males.

cancer biology↗

A Benchmarking Study of Feature Screening Approaches Across Omics Classification Settings

In recent years, high dimensional omics analyses have become more commonplace for investigating complex biological systems. Typically, these studies attempt to identify key biomolecules associated with a particular biological process. Often, machine learning (ML) is used to identify these biomolecules, typically by learning which biomolecules are highly predictive of a treatment, biological outcome, or phenotype. A major challenge of applying ML to high throughput omics is overcoming noise when sample size is limited and unbalanced with respect to tens of thousands of biomolecules measured. Thus, feature selection (the process of reducing the number of predictors) is both a critical and common step in the ML analysis pipeline. While much attention has been given to embedding and wrapping techniques for feature selection in the omics space, filter-based methods for model-free feature selection have appealing theoretical properties. This manuscript evaluates sure screening, a class of filter-based feature selection methods which provide analytical guarantees for true feature set retention. Here, we cover existing feature screening methods based on the sure screening principal, available software, methods to improve feature screening, and contextualize feature screening in the larger discussion of feature selection for omics data analysis. Additionally, a suite of model-free sure screening approaches is applied and compared for several omics biomedical applications in a ML classification context. We identified BcorSIS as the most effective and computationally efficient screening method across various omics datasets, consistently outperforming others like CSIS and DCSIS in runtime. Author SummaryA common goal when analyzing high throughput omics data is to identify key biomolecules which may be important in complex biological systems. This type of large-scale analysis is critical, as it can significantly reduce the set of total biomolecules which are considered for more detailed, targeted analysis. Additionally, biomolecules which are highly predictive of specific phenotypes are useful markers to guide treatment. For instance, identifying which biomolecules are predictive of type 1 diabetes could improve early diagnosis, which may improve patient prognosis. However, modern instrumentation can often detect thousands or tens of thousands of biomolecules, and studies typically have a disproportionately limited number of samples. Many measured biomolecules, or features, are often noisy and uninformative, and overcoming this noise to identify an informative set of biomolecules can be challenging for machine learning (ML) models. Fortunately, there are many feature selection strategies which can intelligently reduce the number of "uninformative" biomolecules an ML model needs to overcome. In this work, sure screening, which is a class of feature selection methods that retains the true feature set under certain conditions, is evaluated in the context of omics data analyses. The pros and cons of various sure screening methods, including software availability, are summarized, and their use in the larger feature selection literature is contextualized. Additionally, we benchmark performance by applying a suite of sure screening approaches on several real omics datasets generated to understand the progression of type 1 diabetes.

bioinformatics↗

Assessing extracellular vesicle proteins as predictive biomarkers for developing type 1 diabetes

Plasma extracellular vesicles (EVs) are considered excellent sources for biomarker discovery since they carry signatures of their cellular origin and disease processes. In this paper, we evaluate the potential of plasma EV proteomics analysis for identifying predictive biomarkers of developing type 1 diabetes (T1D), which results from autoimmune destruction of insulin-producing {beta} cells in the islet. We used strong anion exchange beads (Mag-Net) to capture plasma EVs from 19 donors with islet autoimmunity (diagnosed by circulating autoantibodies against islet proteins - AAB+) vs. 17 control individuals and analyzed their protein cargo by mass spectrometry. The analysis identified and quantified 5,480 proteins, a 3.2-fold increase in proteome coverage compared to our previous T1D biomarker proteomics study that used whole plasma depleted of the 14 most abundant proteins. The Mag-Net approach also detected 1,306 out of the 1,717 proteins (76%) that we previously verified as EV proteins. Statistical tests revealed 448 proteins to be differentially abundant in AAB+ vs control volunteers, including 69 previously verified EV proteins. A functional-enrichment analysis resulted in overrepresentation of 25 pathways among the differentially abundant proteins, including pathways related to autoimmune response and lipid metabolism. The capacity of this data to predict AAB+ was tested with a machine learning analysis using a random forest model, resulting in a receiver operating characteristic-area under the curve of 0.81. Overall, our study indicates that plasma EV proteomics analysis can be an exciting approach for studying biomarkers for developing T1D. Significance of the studyType 1 diabetes (T1D) is a disease characterized by the bodys inability to produce insulin and consequently, to control blood glucose levels. Despite the initial trigger being unclear, the disease development process involves an autoimmune response to the islets of Langerhans, resulting in the death of insulin-producing {beta} cells. There is no cure for the disease, and treatment relies on exogenous administration of insulin. Therefore, preventive therapies that block the autoimmune process are attractive for treating T1D. In fact, anti-CD3 antibody (Teplizumab) delays the onset of T1D by 2 years by targeting T cells. Predictive biomarkers for developing T1D are needed to aid the development and implementation of new therapies and to identify the initial trigger and mechanisms of the islet autoimmune process. In this paper, we assess the potential of plasma extracellular vesicle (EV) proteomics analysis for identifying predictive biomarkers of T1D. Our results show excellent potential of the approach, opening opportunities to perform broader studies to identify biomarkers for developing T1D.

systems biology↗

Single-cell Multiome Analysis of Chromatin State and Transcriptome in the Human Basal Ganglia

The basal ganglia play essential roles in motor control, emotion, learning and reward processing. Their dysfunction contributes to many neurological and psychiatric disorders. However, the gene regulatory programs defining basal ganglia cell-type identity and function remain poorly understood, limiting interpretation of disease-associated non-coding variants. Here, we present the first single-cell multiome atlas of histone modifications and transcriptomes across eight basal ganglia regions from neurotypical adult human donors. Joint profiling reveals cell-type-specific deployment of active and repressive cis-regulatory elements and gene regulatory networks, and suggests a combinatorial homeobox transcription factor code underlying cell identity. Integration with matched spatial transcriptomic MERFISH data uncovers regional heterogeneity of epigenomic landscapes. Comparative analysis between human and mouse medium spiny neurons uncovers conservation of core gene regulatory features. This atlas interprets non-coding risk variants of neuropsychiatric disorders and supports the development of a deep learning model to predict gene regulation and functional effects of disease-associated variants. HIGHLIGHTSO_LIJoint single-cell profiling of transcriptomes and three histone modifications across eight human basal ganglia regions characterizes active and repressive chromatin states at cell-type resolution. C_LIO_LICell-type-specific gene regulatory programs decode combinatorial homeobox TF grammar governing the identity and diversification of basal ganglia neurons. C_LIO_LIIntergrative analyses link noncoding neuropsychiatric risk variants to specific cell types, regulatory elements, and candidate target genes. C_LIO_LIA sequence-to-function deep-learning model predicts gene regulation from DNA sequence and prioritizes functional disease-associated variants. C_LI

genomics↗

Single-Cell Atlas of Transcription and Chromatin States Reveals Regulatory Programs in the Human Brain

Directly measuring chromatin states alongside transcription is essential for understanding how cell-type-specific regulatory programs are established and maintained in the adult human brain. We present a large-scale single-cell multimodal atlas generated by jointly profiling transcriptome with active (H3K27ac) and repressive (H3K27me3) histone modifications across 18 brain regions. We profile >750,000 nuclei spanning 160 cell types and integrate these data with chromatin accessibility, DNA methylation, 3D genome architecture, and spatial transcriptome. This framework annotates >500,000 regulatory elements and resolves cell-type-specific chromatin states. We link enhancers to target genes, infer gene regulatory networks, and classify chromatin interactions, revealing neuron-enriched long-range Polycomb repression of developmental genes. Integrating these maps with GWAS data and sequence-based model prioritizes noncoding variants, effector genes, and vulnerable cell types for neuropsychiatric disorders. Finally, cross-species comparisons show conserved activation but more divergent repression. Together, this study provides a functional reference for interpreting noncoding variants, epigenetic memory, and brain organization. HIGHLIGHTSO_LIJoint single-cell profiling of transcriptomes with active or repressive histone modification in >750,000 nuclei across adult human brain. C_LIO_LIChromatin state annotation of >500,000 candidate cis-regulatory elements distinguishes active enhancers from accessible and Polycomb-repressed regions. C_LIO_LICell-type-resolved regulatory networks and sequence-based deep learning model prioritize functional neuropsychiatric risk variants. C_LIO_LISpatial epigenomic imputation reveals laminar layer-specific Polycomb repression programs. C_LIO_LIIntegration with 3D genome architecture reveals neuron-specific super long-range chromatin loops silencing early developmental genes. C_LIO_LIEvolutionary analysis uncovers conserved active regulatory grammar but divergent repressive landscape. C_LI

genomics↗

Inhibition of β-catenin signaling by Amyloid-β in endothelial cells impairs vascular barrier integrity

Dysfunction of the blood-brain barrier (BBB) is emerging as a critical mediator of Alzheimers Disease (AD) progression and precedes the formation of large Amyloid-{beta} (A{beta}) plaques in AD patients. Maintenance of the blood brain barrier integrity by brain microvascular endothelial cells (BMECs) is essential for brain homeostasis and is in part maintained by WNT/{beta}-catenin signaling. We hypothesized that A{beta} induces blood-brain barrier dysfunction by inhibiting WNT/{beta}- catenin signaling in brain endothelial cells, leading to reduced expression of BBB-related genes and barrier function. In brain endothelial cells, we found that A{beta} directly decreased {beta}-catenin transcriptional activity, but also inhibited activation of {beta}-catenin by the WNT3A peptide. Additionally, A{beta} reduced barrier integrity of ECs, which was in part restored by exposure to exogenous WNT3A. We observed A{beta}-induced inhibition within 3 hours of exposure. A{beta}-induced inhibition of {beta}-catenin signaling was consistent across both immortalized brain ECs and ECs differentiated from human induced pluripotent stem cells(iPSCs). We next investigated human iPSCs with and without the N141I mutation in presenilin-2 (PSEN2), known to increase A{beta} buildup and familial AD risk. We found the AD ECs showed smaller cell size and expressed lower VE-cadherin at the protein level. RNA sequencing revealed that the presence of PSEN2 N141I did not significantly impact gene expression of genes coding for proteins canonically involved in barrier integrity but did show differences in the expression of transposable elements. These results indicate that BBB dysfunction early in AD may be the result of A{beta} in the brain impairing WNT/{beta}-catenin signaling which maintains the barrier integrity of brain endothelial cells.

neuroscience↗

Rab11 is essential to pancreas morphogenesis, lumen formation and endocrine mass.

The molecular links between tissue-level morphogenesis and the differentiation of cell lineages in the pancreas remain elusive despite a decade of studies. We previously showed that in pancreas both these processes depend on proper lumenogenesis. The Rab GTPase Rab11 has been shown to be essential to epithelial lumen formation in vitro, however few studies have addressed its functions in vivo and none have tested its requirement in pancreas. Here, we show that Rab11 is critical to proper pancreas development. Co-deletion of the Rab11 isoforms Rab11A and Rab11B in the developing pancreatic epithelium (Rab11pancDKO) results in ~50% neonatal lethality, and surviving adult Rab11pancDKO mice exhibit defective endocrine function. Loss of Rab11 in the embryonic pancreas results in morphogenetic defects of the epithelium linked to defective lumen formation and interconnection. In contrast to wildtype cells, Rab11pancDKO cells attempt to form multiple lumens, resulting in a failure to coordinate a single apical membrane initiation site (AMIS) between groups of cells. We show that these defects are due to failures in vesicle trafficking, as apical components remain trapped within Rab11pancDKO cells. Together, these observations suggest Rab11 directly regulates epithelial lumen formation and morphogenesis. Our report links intracellular trafficking to organ morphogenesis in vivo, and presents a novel framework for decoding pancreatic development. HIGHLIGHTSO_LIRab11Af/f;Rab11B-/-;Pdx1-Cre pancreas displays disruption of epithelial organization and reduction of endocrine cell mass. C_LIO_LILoss of Rab11 results in disruption of pancreatic lumen continuity due to a failure of lumen formation. C_LIO_LIEpithelial cells lacking Rab11 display abnormal polarity. C_LI

developmental biology↗

Modulation of adaptive immune responses by Akkermansia muciniphila is restricted to an early life window in NOD mice

Early life microbiota drive immune system development and influence risk for immune dysfunction later in life, including the development of type 1 diabetes (T1D). Which specific early-life microbes modulate diabetes risk and the timing of these critical interactions are not well understood. To address this gap in knowledge, we screened for microbes that induce systemic IgG1 responses in young NOD mice. We isolated a strain of Akkermansia muciniphila that potently induces systemic IgG1 antibodies and peripheral regulatory T cells (pTregs). Since this mucus-degrading commensal protects NOD mice from T1D and is associated with lower risk of developing T1D in children, we investigated how A. muciniphila impacts early-life host-commensal interactions using gnotobiotic NOD mice colonized with a defined 9-member bacterial consortium that models the early life microbiome. We find that A. muciniphila potently induces pTregs and enhances antibody responses to other commensal microbes. Remarkably, these effects only occur when A. muciniphila colonizes NOD mice prior to weaning, establishing that the specific window of exposure to A. muciniphila shapes adaptive immune system development in diabetes-susceptible NOD mice. This time dependence provides important evidence that early-life exposure may enhance microbiota-based therapies to prevent T1D. One Sentence SummaryAkkermansia muciniphila induces peripheral Tregs and enhances antibody responses to itself and other commensals during an early life window.

immunology↗

Considering decoupled phenotypic diversification between ontogenetic phases in macroevolution: An example using Triggerfishes (Balistidae)

Across the Tree of Life, most studies of phenotypic disparity and diversification have been restricted to adult organisms. However, many lineages have distinct ontogenetic phases that do not reflect the same traits as their adult forms. Non-adult disparity patterns are particularly important to consider for coastal ray-finned fishes, which often have juvenile phases with distinct phenotypes. These juvenile forms are often associated with sheltered nursery environments, with phenotypic shifts between adults and juvenile stages that are readily apparent in locomotor morphology. However, whether this ontogenetic variation in locomotor morphology reflects a decoupling of diversification dynamics between life stages remains unknown. Here we investigate the evolutionary dynamics of locomotor morphology between adult and juvenile triggerfishes. Integrating a time-calibrated phylogenetic framework with geometric morphometric approaches and measurement data of fin aspect ratio and incidence, we reveal a mismatch between morphospace occupancy, the evolution of morphological disparity, and the tempo of trait evolution between life stages. Collectively, our results illuminate how the heterogeneity of morpho-functional adaptations can decouple the mode and tempo of morphological diversification between ontogenetic stages.

evolutionary biology↗

Spatial transcriptomics using combinatorial fluorescence spectral and lifetime encoding, imaging and analysis

Multiplexed mRNA profiling in the spatial context provides important new information enabling basic research and clinical applications. Unfortunately, most existing spatial transcriptomics methods are limited due to either low multiplexing or assay complexity. Here, we introduce a new spatialomics technology, termed Multi Omic Single-scan Assay with Integrated Combinatorial Analysis (MOSAICA), that integrates in situ labeling of mRNA and protein markers in cells or tissues with combinatorial fluorescence spectral and lifetime encoded probes, spectral and time-resolved fluorescence imaging, and machine learning-based target decoding. This technology is the first application combining the biophotonic techniques, Spectral and Fluorescence Lifetime Imaging and Microscopy (FLIM), to the field of spatial transcriptomics. By integrating the time dimension with conventional spectrum-based measurements, MOSAICA enables direct and highly-multiplexed in situ spatial biomarker profiling in a single round of staining and imaging while providing error correction removal of background autofluorescence. We demonstrate mRNA encoding using combinatorial spectral and lifetime labeling and target decoding and quantification using a phasor-based image segmentation and machine learning clustering technique. We then showcase MOSAICAs multiplexing scalability in detecting 10-plex targets in fixed colorectal cancer cells using combinatorial labeling of only five fluorophores with facile error-correction and removal of autofluorescent moieties. MOSAICAs analysis is strongly correlated with sequencing data (Pearsons r = 0.9) and was further benchmarked using RNAscopeand LGC Stellaris. We further apply MOSAICA for multiplexed analysis of clinical melanoma Formalin-Fixed Paraffin-Embedded (FFPE) tissues that have a high degree of tissue scattering and intrinsic autofluorescence, demonstrating the robustness of the approach. We then demonstrate simultaneous co-detection of protein and mRNA in colorectal cancer cells. MOSAICA represents a simple, versatile, and scalable tool for targeted spatial transcriptomics analysis that can find broad utility in constructing human cell atlases, elucidating biological and disease processes in the spatial context, and serving as companion diagnostics for stratified patient care.

bioengineering↗

Definitive Hematopoietic Stem Cells Minimally Contribute to Embryonic Hematopoiesis

Hematopoietic stem cells (HSCs) are rare cells that arise in the embryo and sustain adult hematopoiesis. Although the functional potential of nascent HSCs is detectable by transplantation, their native contribution during development is unknown, in part due to the overlapping genesis and marker gene expression with other embryonic blood progenitors. Using single cell transcriptomics, we defined gene signatures that distinguish nascent HSCs from embryonic blood progenitors. Applying a new lineage tracing approach, we selectively tracked HSC output in situ and discovered significantly delayed lymphomyeloid contribution. Using a novel inducible HSC injury model, we demonstrated a negligible impact on larval lymphomyelopoiesis following HSC depletion. HSCs are not merely dormant at this developmental stage as they showed robust regeneration after injury. Combined, our findings illuminate that nascent HSCs self-renew but display differentiation latency, while HSC-independent embryonic progenitors sustain developmental hematopoiesis. Understanding the differences among embryonic HSC and progenitor populations will guide improved de novo generation and expansion of functional HSCs.

developmental biology↗

Multi-platform discovery of haplotype-resolved structural variation in human genomes

The incomplete identification of structural variants (SVs) from whole-genome sequencing data limits studies of human genetic diversity and disease association. Here, we apply a suite of long-read, short-read, and strand-specific sequencing technologies, optical mapping, and variant discovery algorithms to comprehensively analyze three human parent-child trios to define the full spectrum of human genetic variation in a haplotype-resolved manner. We identify 818,054 indel variants (<50 bp) and 27,622 SVs ([&ge;]50 bp) per human genome. We also discover 156 inversions per genome--most of which previously escaped detection. Fifty-eight of the inversions we discovered intersect with the critical regions of recurrent microdeletion and microduplication syndromes. Taken together, our SV callsets represent a sevenfold increase in SV detection compared to most standard high-throughput sequencing studies, including those from the 1000 Genomes Project. The method and the dataset serve as a gold standard for the scientific community and we make specific recommendations for maximizing structural variation sensitivity for future large-scale genome sequencing studies.

genomics↗