Highest fusion performance without harmful edge energy bursts in tokamak

The path of tokamak fusion and International thermonuclear experimental reactor (ITER) is maintaining high-performance plasma to produce sufficient fusion power. This effort is hindered by the transient energy burst arising from the instabilities at the boundary of plasmas. Conventional 3D magnetic perturbations used to suppress these instabilities often degrade fusion performance and increase the risk of other instabilities. This study presents an innovative 3D field optimization approach that leverages machine learning and real-time adaptability to overcome these challenges. Implemented in the DIII-D and KSTAR tokamaks, this method has consistently achieved reactor-relevant core confinement and the highest fusion performance without triggering damaging bursts. This is enabled by advances in the physics understanding of self-organized transport in the plasma edge and machine learning techniques to optimize the 3D field spectrum. The success of automated, real-time adaptive control of such complex systems paves the way for maximizing fusion efficiency in ITER and beyond while minimizing damage to device components.

CRISPR/Cas9 gene editing in Drosophila via visual selection in a summer classroom

CRISPR/Cas9 methods are a powerful in vivo approach to edit the genome of Drosophila melanogaster. To convert existing Drosophila GAL4 lines to LexA driver lines in a secondary school classroom setting, we applied the CRISPR-based genetic approach to a collection of Gal4 'driver' lines. The integration of the yellow+ coat color marker into homology-assisted CRISPR knock-in (HACK) enabled visual selection of Gal4-to-LexA conversions using brightfield stereo-microscopy available in a broader set of standard classrooms. Here, we report the successful conversion of eleven Gal4 lines with expression in neuropeptide-expressing cells into corresponding, novel LexA drivers. The conversion was confirmed by LexA- and Gal4-specific GFP reporter gene expression. This curriculum was successfully implemented in a summer course running 16 hours/week for seven weeks. The modularity, flexibility, and compactness of this course should enable development of similar classes in secondary schools and undergraduate curricula, to provide opportunities for experience-based science instruction, and university-secondary school collaborations that simultaneously fulfill research needs in the community of science.

RFX6 Maintains Gene Expression and Function of Adult Human Islet α-Cells

Mutations in the gene encoding the transcription factor regulatory factor X-box binding 6 (RFX6) are associated with human diabetes. Within pancreatic islets, RFX6 expression is most abundant in islet α-cells, and α-cell RFX6 expression is altered in diabetes. However, the roles of RFX6 in regulating gene expression, glucagon output, and other crucial human adult α-cell functions are not yet understood. We developed a method for selective genetic targeting of human α-cells and assessed RFX6-dependent α-cell function. RFX6 suppression with RNA interference led to impaired α-cell exocytosis and dysregulated glucagon secretion in vitro and in vivo. By contrast, these phenotypes were not observed with RFX6 suppression across all islet cells. Transcriptomics in α-cells revealed RFX6-dependent expression of genes governing nutrient sensing, hormone processing, and secretion, with some of these exclusively expressed in human α-cells. Mapping of RFX6 DNA-binding sites in primary human islet cells identified a subset of direct RFX6 target genes. Together, these data unveil RFX6-dependent genetic targets and mechanisms crucial for regulating adult human α-cell function.

ARTICLE HIGHLIGHTS

Simplified homology-assisted CRISPR for gene editing in Drosophila

In vivo genome editing with clustered regularly interspaced short palindromic repeats (CRISPR)/Cas9 generates powerful tools to study gene regulation and function. We revised the homology-assisted CRISPR knock-in method to convert Drosophila GAL4 lines to LexA lines using a new universal knock-in donor strain. A balancer chromosome-linked donor strain with both body color (yellow) and eye red fluorescent protein (RFP) expression markers simplified the identification of LexA knock-in using light or fluorescence microscopy. A second balancer chromosome-linked donor strain readily converted the second chromosome-linked GAL4 lines regardless of target location in the cis-chromosome but showed limited success for the third chromosome-linked GAL4 lines. We observed a consistent and robust expression of the yellow transgene in progeny harboring a LexA knock-in at diverse genomic locations. Unexpectedly, the expression of the 3xP3-RFP transgene in the "dual transgene" cassette was significantly increased compared with that of the original single 3xP3-RFP transgene cassette in all tested genomic locations. Using this improved screening approach, we generated 16 novel LexA lines; tissue expression by the derived LexA and originating GAL4 lines was similar or indistinguishable. In collaboration with 2 secondary school classes, we also established a systematic workflow to generate a collection of LexA lines from frequently used GAL4 lines.

Multiplexed CRISPR gene editing in primary human islet cells with Cas9 ribonucleoprotein

Successful genome editing in primary human islets could reveal features of the genetic regulatory landscape underlying β cell function and diabetes risk. Here, we describe a CRISPR-based strategy to interrogate functions of predicted regulatory DNA elements using electroporation of a complex of Cas9 ribonucleoprotein (Cas9 RNP) and guide RNAs into primary human islet cells. We successfully targeted coding regions including the PDX1 exon 1, and non-coding DNA linked to diabetes susceptibility. CRISPR-Cas9 RNP approaches revealed genetic targets of regulation by DNA elements containing candidate diabetes risk SNPs, including an in vivo enhancer of the MPHOSPH9 gene. CRISPR-Cas9 RNP multiplexed targeting of two cis-regulatory elements linked to diabetes risk in PCSK1, which encodes an endoprotease crucial for Insulin processing, also demonstrated efficient simultaneous editing of PCSK1 regulatory elements, resulting in impaired β cell PCSK1 regulation and Insulin secretion. Multiplex CRISPR-Cas9 RNP provides powerful approaches to investigate and elucidate human islet cell gene regulation in health and diabetes.

HNF1α maintains pancreatic α and β cell functions in primary human islets

HNF1A haploinsufficiency underlies the most common form of human monogenic diabetes (HNF1A-maturity onset diabetes of the young [HNF1A-MODY]), and hypomorphic HNF1A variants confer type 2 diabetes risk. But a lack of experimental systems for interrogating mature human islets has limited our understanding of how the transcription factor HNF1α regulates adult islet function. Here, we combined conditional genetic targeting in human islet cells, RNA-Seq, chromatin mapping with cleavage under targets and release using nuclease (CUT&RUN), and transplantation-based assays to determine HNF1α-regulated mechanisms in adult human pancreatic α and β cells. Short hairpin RNA-mediated (shRNA-mediated) suppression of HNF1A in primary human pseudoislets led to blunted insulin output and dysregulated glucagon secretion after transplantation in mice, recapitulating phenotypes observed in patients with diabetes. These deficits corresponded with altered expression of genes encoding factors critical for hormone secretion, including calcium channel subunits, ATPase transporters, and extracellular matrix constituents. Additionally, HNF1A loss led to upregulation of transcriptional repressors, providing evidence for a mechanism of transcriptional derepression through HNF1α. CUT&RUN mapping of HNF1α DNA binding sites in primary human islets imputed a subset of HNF1α-regulated genes as direct targets. These data elucidate mechanistic links between HNF1A loss and diabetic phenotypes in mature human α and β cells.

Search for Boosted Dark Matter in COSINE-100

We search for energetic electron recoil signals induced by boosted dark matter (BDM) from the galactic center using the COSINE-100 array of NaI(Tl) crystal detectors at the Yangyang Underground Laboratory. The signal would be an excess of events with energies above 4 MeV over the well-understood background. Because no excess of events are observed in a 97.7  kg·yr exposure, we set limits on BDM interactions under a variety of hypotheses. Notably, we explored the dark photon parameter space, leading to competitive limits compared to direct dark photon search experiments, particularly for dark photon masses below 4 MeV and considering the invisible decay mode. Furthermore, by comparing our results with a previous BDM search conducted by the Super-Kamionkande experiment, we found that the COSINE-100 detector has advantages in searching for low-mass dark matter. This analysis demonstrates the potential of the COSINE-100 detector to search for MeV electron recoil signals produced by the dark sector particle interactions.

Multiplexed CRISPR gene editing in primary human islet cells with Cas9 ribonucleoprotein

Successful genome editing in primary human islets could reveal features of the genetic regulatory landscape underlying β cell function and diabetes risk. Here, we describe a CRISPR-based strategy to interrogate functions of predicted regulatory DNA elements using electroporation of a complex of Cas9 ribonucleoprotein (Cas9 RNP) and guide RNAs into primary human islet cells. We successfully targeted coding regions including the PDX1 exon 1, and non-coding DNA linked to diabetes susceptibility. CRISPR/Cas9 RNP approaches revealed genetic targets of regulation by DNA elements containing candidate diabetes risk SNPs, including an in vivo enhancer of the MPHOSPH9 gene. CRISPR/Cas9 RNP multiplexed targeting of two cis-regulatory elements linked to diabetes risk in PCSK1, which encodes an endoprotease crucial for insulin processing, also demonstrated efficient simultaneous editing of PCSK1 regulatory elements, resulting in impaired β cell PCSK1 regulation and insulin secretion. Multiplex CRISPR/Cas9 RNP provides powerful approaches to investigate and elucidate human islet cell gene regulation in health and diabetes.

Generation of LexA enhancer-trap lines in Drosophila by an international scholastic network

Conditional gene regulation in Drosophila through binary expression systems like the LexA-LexAop system provides a superb tool for investigating gene and tissue function. To increase the availability of defined LexA enhancer trap insertions, we present molecular, genetic, and tissue expression studies of 301 novel Stan-X LexA enhancer traps derived from mobilization of the index SX4 line. This includes insertions into distinct loci on the X, II, and III chromosomes that were not previously associated with enhancer traps or targeted LexA constructs, an insertion into ptc, and seventeen insertions into natural transposons. A subset of enhancer traps was expressed in CNS neurons known to produce and secrete insulin, an essential regulator of growth, development, and metabolism. Fly lines described here were generated and characterized through studies by students and teachers in an international network of genetics classes at public, independent high schools, and universities serving a diversity of students, including those underrepresented in science. Thus, a unique partnership between secondary schools and university-based programs has produced and characterized novel resources in Drosophila, establishing instructional paradigms devoted to unscripted experimental science.

Integrating genetics with single-cell multiomic measurements across disease states identifies mechanisms of beta cell dysfunction in type 2 diabetes

Dysfunctional pancreatic islet beta cells are a hallmark of type 2 diabetes (T2D), but a comprehensive understanding of the underlying mechanisms, including gene dysregulation, is lacking. Here we integrate information from measurements of chromatin accessibility, gene expression and function in single beta cells with genetic association data to nominate disease-causal gene regulatory changes in T2D. Using machine learning on chromatin accessibility data from 34 nondiabetic, pre-T2D and T2D donors, we identify two transcriptionally and functionally distinct beta cell subtypes that undergo an abundance shift during T2D progression. Subtype-defining accessible chromatin is enriched for T2D risk variants, suggesting a causal contribution of subtype identity to T2D. Both beta cell subtypes exhibit activation of a stress-response transcriptional program and functional impairment in T2D, which is probably induced by the T2D-associated metabolic environment. Our findings demonstrate the power of multimodal single-cell measurements combined with machine learning for characterizing mechanisms of complex diseases.

Multifaceted role for p53 in pancreatic cancer suppression

The vast majority of human pancreatic ductal adenocarcinomas (PDACs) harbor TP53 mutations, underscoring p53's critical role in PDAC suppression. PDAC can arise when pancreatic acinar cells undergo acinar-to-ductal metaplasia (ADM), giving rise to premalignant pancreatic intraepithelial neoplasias (PanINs), which finally progress to PDAC. The occurrence of TP53 mutations in late-stage PanINs has led to the idea that p53 acts to suppress malignant transformation of PanINs to PDAC. However, the cellular basis for p53 action during PDAC development has not been explored in detail. Here, we leverage a hyperactive p53 variant-p5353,54-which we previously showed is a more robust PDAC suppressor than wild-type p53, to elucidate how p53 acts at the cellular level to dampen PDAC development. Using both inflammation-induced and KRASG12D-driven PDAC models, we find that p5353,54 both limits ADM accumulation and suppresses PanIN cell proliferation and does so more effectively than wild-type p53. Moreover, p5353,54 suppresses KRAS signaling in PanINs and limits effects on the extracellular matrix (ECM) remodeling. While p5353,54 has highlighted these functions, we find that pancreata in wild-type p53 mice similarly show less ADM, as well as reduced PanIN cell proliferation, KRAS signaling, and ECM remodeling relative to Trp53-null mice. We find further that p53 enhances chromatin accessibility at sites controlled by acinar cell identity transcription factors. These findings reveal that p53 acts at multiple stages to suppress PDAC, both by limiting metaplastic transformation of acini and by dampening KRAS signaling in PanINs, thus providing key new understanding of p53 function in PDAC.

Integration of single-cell multiomic measurements across disease states with genetics identifies mechanisms of beta cell dysfunction in type 2 diabetes

Altered function and gene regulation of pancreatic islet beta cells is a hallmark of type 2 diabetes (T2D), but a comprehensive understanding of mechanisms driving T2D is still missing. Here we integrate information from measurements of chromatin activity, gene expression and function in single beta cells with genetic association data to identify disease-causal gene regulatory changes in T2D. Using machine learning on chromatin accessibility data from 34 non-diabetic, pre-T2D and T2D donors, we robustly identify two transcriptionally and functionally distinct beta cell subtypes that undergo an abundance shift in T2D. Subtype-defining active chromatin is enriched for T2D risk variants, suggesting a causal contribution of subtype identity to T2D. Both subtypes exhibit activation of a stress-response transcriptional program and functional impairment in T2D, which is likely induced by the T2D-associated metabolic environment. Our findings demonstrate the power of multimodal single-cell measurements combined with machine learning for identifying mechanisms of complex diseases.

A genome-wide CRISPR screen identifies CALCOCO2 as a regulator of beta cell function influencing type 2 diabetes risk

Identification of the genes and processes mediating genetic association signals for complex diseases represents a major challenge. As many of the genetic signals for type 2 diabetes (T2D) exert their effects through pancreatic islet-cell dysfunction, we performed a genome-wide pooled CRISPR loss-of-function screen in a human pancreatic beta cell line. We assessed the regulation of insulin content as a disease-relevant readout of beta cell function and identified 580 genes influencing this phenotype. Integration with genetic and genomic data provided experimental support for 20 candidate T2D effector transcripts including the autophagy receptor CALCOCO2. Loss of CALCOCO2 was associated with distorted mitochondria, less proinsulin-containing immature granules and accumulation of autophagosomes upon inhibition of late-stage autophagy. Carriers of T2D-associated variants at the CALCOCO2 locus further displayed altered insulin secretion. Our study highlights how cellular screens can augment existing multi-omic efforts to support mechanistic understanding and provide evidence for causal effects at genome-wide association studies loci.

Curative islet and hematopoietic cell transplantation in diabetic mice without toxic bone marrow conditioning

Mixed hematopoietic chimerism can promote immune tolerance of donor-matched transplanted tissues, like pancreatic islets. However, adoption of this strategy is limited by the toxicity of standard treatments that enable donor hematopoietic cell engraftment. Here, we address these concerns with a non-myeloablative conditioning regimen that enables hematopoietic chimerism and allograft tolerance across fully mismatched major histocompatibility complex (MHC) barriers. Treatment with an αCD117 antibody, targeting c-Kit, administered with T cell-depleting antibodies and low-dose radiation permits durable multi-lineage chimerism in immunocompetent mice following hematopoietic cell transplant. In diabetic mice, co-transplantation of donor-matched islets and hematopoietic cells durably corrects diabetes without chronic immunosuppression and no appreciable evidence of graft-versus-host disease (GVHD). Donor-derived thymic antigen-presenting cells and host-derived peripheral regulatory T cells are likely mediators of allotolerance. These findings provide the foundation for safer bone marrow conditioning and cell transplantation regimens to establish hematopoietic chimerism and islet allograft tolerance.

Early adolescents’ sexual and reproductive health literacy in Lao PDR

Background

Sexual and reproductive health literacy (SRHL) refers to the ability to access, understand, appraise, and apply information for decision-making related to sexual and reproductive health. The low level of SRHL in adolescents increases their sexually risky behaviors and endangers sexual health. Although early adolescence is a critical development period for forming initial views on sexuality and is often a time for attempting risky behaviors, studies on SRHL for early adolescents are fairly limited in Las PDR. As an initial step for the development of a global health project between Lao PDR and South Korea, this study assessed the level of SRHL and the differences in gender among early adolescents in Lao PDR.

Methods

Participants were 235 students conveniently recruited from one junior high school each in two provinces in Lao PDR. SRHL was measured using the 39-item Teen Pregnancy Health Literacy scale consisting of 4 subscales of finding, understanding, appraisal, and application. The scores were classified into inadequate, problematic, sufficient, and excellent using the SRHL index formula. The mean differences in gender were compared using t-test.

Results

The mean of the SRHL scores of the participants was 19.07 (±10.57). The mean score was significantly lower for girls, at 17.67 (±11.22) than for boys, at 21.37 (±9.05) (p = .006). Significant differences were further identified in all four sub-domains of SRHL: finding (p = .025), understanding (p = .005), appraisal (p = .041), and application (p = .029). The majority of participants (91.7%) were categorized as having an ‘inadequate’ or ‘problematic’ level of SRHL.

Conclusions

The level of SRHL among most early adolescents was found to be inadequate. The level of SRHL among girls was much lower than that among boys. The findings suggest a gender-specific approach to developing health education programs to improve SRHL among early adolescents and prevent future sexually risky behaviors in Lao PDR.

Key messages

Characterization of rhodanine derivatives as potential disease-modifying drugs for experimental mouse osteoarthritis

OBJECTIVE

This study was performed to characterize selected rhodanine derivatives as potential preclinical disease-modifying drugs for experimental osteoarthritis (OA) in mice.

METHODS

Three rhodanine derivatives, designated rhodanine (R)-501, R-502, and R-503, were selected as candidate OA disease-modifying drugs. Their effects were evaluated by intra-articular (IA) injection in OA mouse models induced by DMM (destabilization of the medial meniscus) or adenoviral overexpression in joint tissues of hypoxia-inducible factor (HIF)-2α or zinc importer ZIP8. The regulatory mechanisms impacted by the rhodanine derivatives were examined in primary-culture chondrocytes and fibroblast-like synoviocytes (FLS).

RESULTS

All three rhodanine derivatives inhibited OA development caused by DMM or overexpression of HIF-2α or ZIP8. Compared to vehicle-treated group, for example, IA injection of R-501 in DMM-operated mice reduced median OARSI grade from 3.78 (IQR 3.00-5.00) to 1.89 (IQR 0.94-2.00, P = 0.0001). R-502 and R-503 also reduced from 3.67 (IQR 2.11-4.56) to 2.00 (IQR 1.00-2.00, P = 0.0030) and 2.00 (IQR 1.83-2.67, P = 0.0378), respectively. Mechanistically, the rhodanine derivatives inhibited the nuclear localization and transcriptional activity of HIF-2α in chondrocytes and FLS. They did not bind to Zn²⁺ or modulate Zn²⁺ homeostasis in chondrocytes or FLS; instead, they inhibited the nuclear localization and transcriptional activity of the Zn²⁺-dependent transcription factor, MTF1. HIF-2α, ZIP8, and interleukin-1β could upregulate matrix-degrading enzymes in chondrocytes and FLS, and the rhodanine derivatives inhibited these effects.

CONCLUSION

IA administration of rhodanine derivatives significantly reduced OA pathogenesis in various mouse models, demonstrating that these derivatives have disease-modifying therapeutic potential against OA pathogenesis.

Single-cell transcriptome and accessible chromatin dynamics during endocrine pancreas development

Delineating gene regulatory networks that orchestrate cell-type specification is a continuing challenge for developmental biologists. Single-cell analyses offer opportunities to address these challenges and accelerate discovery of rare cell lineage relationships and mechanisms underlying hierarchical lineage decisions. Here, we describe the molecular analysis of mouse pancreatic endocrine cell differentiation using single-cell transcriptomics, chromatin accessibility assays coupled to genetic labeling, and cytometry-based cell purification. We uncover transcription factor networks that delineate β-, α-, and δ-cell lineages. Through genomic footprint analysis, we identify transcription factor-regulatory DNA interactions governing pancreatic cell development at unprecedented resolution. Our analysis suggests that the transcription factor Neurog3 may act as a pioneer transcription factor to specify the pancreatic endocrine lineage. These findings could improve protocols to generate replacement endocrine cells from renewable sources, like stem cells, for diabetes therapy.

Islet cell replacement and transplantation immunology in a mouse strain with inducible diabetes

Improved models of experimental diabetes are needed to develop cell therapies for diabetes. Here, we introduce the B6 RIP-DTR mouse, a model of experimental diabetes in fully immunocompetent animals. These inbred mice harbor the H2^b major histocompatibility complex (MHC), selectively express high affinity human diphtheria toxin receptor (DTR) in islet β-cells, and are homozygous for the Ptprc^a (CD45.1) allele rather than wild-type Ptprc^b (CD45.2). 100% of B6 RIP-DTR mice rapidly became diabetic after a single dose of diphtheria toxin, and this was reversed indefinitely after transplantation with islets from congenic C57BL/6 mice. By contrast, MHC-mismatched islets were rapidly rejected, and this allotransplant response was readily monitored via blood glucose and graft histology. In peripheral blood of B6 RIP-DTR with mixed hematopoietic chimerism, CD45.2 BALB/c donor blood immune cells were readily distinguished from host CD45.1 cells by flow cytometry. Reliable diabetes induction and other properties in B6 RIP-DTR mice provide an important new tool to advance transplant-based studies of islet replacement and immunomodulation to treat diabetes.

The Tabula Sapiens: A multiple-organ, single-cell transcriptomic atlas of humans

Molecular characterization of cell types using single-cell transcriptome sequencing is revolutionizing cell biology and enabling new insights into the physiology of human organs. We created a human reference atlas comprising nearly 500,000 cells from 24 different tissues and organs, many from the same donor. This atlas enabled molecular characterization of more than 400 cell types, their distribution across tissues, and tissue-specific variation in gene expression. Using multiple tissues from a single donor enabled identification of the clonal distribution of T cells between tissues, identification of the tissue-specific mutation rate in B cells, and analysis of the cell cycle state and proliferative potential of shared cell types across tissues. Cell type-specific RNA splicing was discovered and analyzed across tissues within an individual.

A LexAop > UAS > QUAS trimeric plasmid to generate inducible and interconvertible Drosophila overexpression transgenes

The existence of three independent binary systems for conditional gene expression (Gal4/UAS; LexA/LexAop; QF/QUAS) has greatly expanded versatile genetic analyses in the Drosophila melanogaster; however, the experimental application of these tools is limited by the need to generate multiple collections of noninterchangeable transgenic fly strains for each inducible gene expression system. To address this practical limitation, we developed a modular vector that contains the regulatory elements from all three binary systems, enabling Gal4-, LexA- or QF-dependent expression of transgenes. Our methods also incorporate DNA elements that facilitate independent site-specific recombination and elimination of regulatory UAS, LexAop or QUAS modules with spatial and temporal control, thus offering unprecedented possibilities and logistical advantages for in vivo genetic modulation and efficient interconversion of overexpression transgenic fly lines.

Transgenic Drosophila lines for LexA-dependent gene and growth regulation

Conditional expression of short hairpin RNAs with binary genetic systems is an indispensable tool for studying gene function. Addressing mechanisms underlying cell-cell communication in vivo benefits from simultaneous use of 2 independent gene expression systems. To complement the abundance of existing Gal4/UAS-based resources in Drosophila, we and others have developed LexA/LexAop-based genetic tools. Here, we describe experimental and pedagogical advances that promote the efficient conversion of Drosophila Gal4 lines to LexA lines, and the generation of LexAop-short hairpin RNA lines to suppress gene function. We developed a CRISPR/Cas9-based knock-in system to replace Gal4 coding sequences with LexA, and a LexAop-based short hairpin RNA expression vector to achieve short hairpin RNA-mediated gene silencing. We demonstrate the use of these approaches to achieve targeted genetic loss-of-function in multiple tissues. We also detail our development of secondary school curricula that enable students to create transgenic flies, thereby magnifying the production of well-characterized LexA/LexAop lines for the scientific community. The genetic tools and teaching methods presented here provide LexA/LexAop resources that complement existing resources to study intercellular communication coordinating metazoan physiology and development.

Fly Cell Atlas: A single-nucleus transcriptomic atlas of the adult fruit fly

For more than 100 years, the fruit fly Drosophila melanogaster has been one of the most studied model organisms. Here, we present a single-cell atlas of the adult fly, Tabula Drosophilae, that includes 580,000 nuclei from 15 individually dissected sexed tissues as well as the entire head and body, annotated to >250 distinct cell types. We provide an in-depth analysis of cell type-related gene signatures and transcription factor markers, as well as sexual dimorphism, across the whole animal. Analysis of common cell types between tissues, such as blood and muscle cells, reveals rare cell types and tissue-specific subtypes. This atlas provides a valuable resource for the Drosophila community and serves as a reference to study genetic perturbations and disease models at single-cell resolution.