Aplastic anemia (AA) is a non-neoplastic bone marrow failure syndrome caused by the destruction of hematopoietic stem and progenitor cells by the immune system. However, in some cases of AA, a small ...number of specific clones with gene mutations are observed without clinical manifestations. Cases with mutated PIG-A, BCOR/BCORL1, or HLA class I allele clones respond better to immunosuppressive therapies (ISTs). Cases with MDS-related clones, such as DNMT3A or ASXL1 mutations, are at a higher risk for secondary MDS. In this review, I will focus on the clonal hematopoiesis (CH) in AA and discuss its clinical significance, including its impact on disease boundaries and transition. I will also discuss the pathophysiology and diagnosis of hypoplastic MDS, a type of MDS that responds to ISTs.
Background
Single‐cell transcriptomics allows parallel analysis of multiple cell types in tissues. Because testes comprise somatic cells and germ cells at various stages of spermatogenesis, ...single‐cell RNA sequencing is a powerful tool for investigating the complex process of spermatogenesis. However, single‐cell RNA sequencing analysis needs extensive knowledge of experimental technologies and bioinformatics, making it difficult for many, particularly experimental biologists and clinicians, to use it.
Methods
Aiming to make single‐cell RNA sequencing analysis familiar, this review article presents an overview of experimental and computational methods for single‐cell RNA sequencing analysis with a history of transcriptomics. In addition, combining the PubMed search and manual curation, this review also provides a summary of recent novel insights into human and mouse spermatogenesis obtained using single‐cell RNA sequencing analyses.
Main Findings
Single‐cell RNA sequencing identified mesenchymal cells and type II innate lymphoid cells as novel testicular cell types in the adult mouse testes, as well as detailed subtypes of germ cells. This review outlines recent discoveries into germ cell development and subtypes, somatic cell development, and cell–cell interactions.
Conclusion
The findings on spermatogenesis obtained using single‐cell RNA sequencing may contribute to a deeper understanding of spermatogenesis and provide new directions for male fertility therapy.
Chloropupukeananin is a natural product that inhibits HIV-1 replication and has antitumor activity. Its structure consists of a chlorinated tricyclo4.3.1.03,7decane core skeleton with an array of ...highly oxidized multifunctional groups. In the biosynthesis of chloropupukeananin, (+)-iso-A82775C and (−)-maldoxin are employed as biosynthetic precursors for the intermolecular Diels–Alder and carbonyl–ene reactions, followed by the migration of the p-orcellinate group. Chloropupukeanolides and chloropestolides are intermediates and isomers in biosynthesis; their unique chemical structures and biosynthetic pathways have attracted significant attention from synthetic chemists. In this review, I present the synthetic studies on chloropupukeananin and its related compounds that have been conducted thus far.
Cyclic voltammetry is a very useful tool for estimating several parameters such as electron transfer kinetics, diffusivity of active species, and effective surface area in a redox system. In cyclic ...voltammetry modeling, a simulated cyclic voltammogram is usually treated by neglecting the nonlinear effects of an electrical double layer and ohmic resistance. However, this approach leads to inaccurate prediction of such parameters. In this study, numerical modeling, including the combined effects of ohmic resistance, constant phase element, mass transfer, and faradaic processes, of cyclic voltammetry was carried out to show that, using this approach, nonlinear behaviors of the time-domain response of cyclic voltammetry can be encompassed. The model showed a good agreement with the experimental measurements. Furthermore, the numerical investigation of ohmic resistance and constant phase element effects on a cyclic voltammogram were performed.
•Effects of CPE and ohmic resistance are encompassed in the proposed model.•The model conveniently helps separating the faradaic and non-faradaic currents.•The faradaic and non-faradaic currents are coupled through the ohmic drop effects.•CPE and ohmic resistance significantly affect cyclic voltammetry responses.
A new method for constructing the bicyclo3.2.1octane skeleton was developed by the intramolecular alkylation of a nitrile-side-chain-containing cyclohexanone derivative. The cyclization precursors ...were prepared via the stereoselective bromination of the triisopropylsilyl enol ethers of 4-substituted cyclohexanones. Upon treatment with LiNEt2, the bromonitriles underwent a stereoselective intramolecular SN2 reaction to afford bicyclo3.2.1octane derivatives with a cyano group on the convex face. The total synthesis of 2-isocyanoallopupukeanane (6.5% yield) from methyl vinyl ketone was accomplished via a 17-step transformation.
(+)-Iso-A82775C is a proposed biosynthetic precursor of the chloropupukeananin family and an important intermediate for related natural products. The first enantioselective total synthesis of ...(+)-iso-A82775C (18 steps, 2.2% overall yield) toward the eventual biomimetic total synthesis of chloropupukeananin is described. The key steps are (1) the enantioselective Diels–Alder reaction of 4-bromo-3-hydroxy-2-pyrone with methyl 2-chloroacrylate using cinchonine as an organocatalyst and (2) the anti-selective Cu-mediated SN2′ reaction to afford the axially chiral vinylallene moiety.
Reconstituting the ovarian follicle
Recent advances have enabled the generation of oocytes from pluripotent stem cells in vitro. However, these cells require a somatic environment to develop fully as ...reproductive cells. Yoshino
et al.
applied what is known about differentiation processes in vivo to determine a culture condition to differentiate embryonic stem cells into gonadal somatic cell–like cells (see the Perspective by Yang and Ng). When the embryonic stem cell–generated ovarian gonadal tissue was combined with early primordial germ cells or in vitro–derived primordial germ cell–like cells, germ cells developed into viable oocytes within the reconstituted follicles that could be fertilized and result in viable offspring. This system enables an alternative method for mouse gamete production and advances our understanding of mammalian reproduction and development.
Science
, abe0237, this issue p.
eabe0237
; see also abj8347, p.
282
Functional eggs were successfully produced in a mouse ovarian environment reconstituted from pluripotent stem cells.
INTRODUCTION
Germ cells develop in a specific environment in the reproductive organs. Throughout oogenesis, oocytes are encapsulated by somatic cells in follicle structures that provide numerous signals and components essential for key events in oocyte development, such as meiosis and growth. The interaction between the oocyte and the somatic follicular cells is regulated in a stage-dependent manner. Recently, in vitro gametogenesis, reconstitution of germ cell development in culture using pluripotent stem cells, has been developed in mammalian species, including mice and humans. In mice, functional oocytes can be produced from pluripotent stem cell–derived primordial germ cell–like cells (PGCLCs) by reaggregation with embryonic ovarian somatic cells at embryonic day 12.5. Therefore, in vitro gametogenesis is expected to be an innovative means of producing a robust number of oocytes in culture. This should be particularly useful for application to humans and endangered animals. However, the in vitro reconstitution of germ cell development is highly dependent on the somatic cell environment provided by embryonic ovarian tissue, which is difficult to obtain from mammalian species. Here, we provide a model system that reconstitutes the ovarian somatic cell environment using mouse pluripotent stem cells.
RATIONALE
During mouse development, the embryonic ovaries originate from the nascent mesoderm, followed by the intermediate mesoderm and coelomic epithelium at the genital ridge region. For the formation of embryonic ovarian somatic cells from mouse pluripotent stem cells, appropriate signals need to be provided in culture to mimic those embryonic events. Using mouse embryonic stem cells (mESCs) harboring reporter constructs that monitor the expression of key genes for each step, we set out to explore culture conditions for the recreation of the differentiation process. Faithful gene expression and functionality should be conferred in induced embryonic ovarian somatic cells under the appropriate conditions. The functionality of the induced cells should be verified by the ability to support the generation of functional oocytes capable of fertilization and subsequent development.
RESULTS
Based on reporter gene expression, we determined a series of culture conditions that recreate the differentiation process from pluripotent cells to gonadal somatic cells in a stepwise manner. Under these conditions, mESCs differentiated into fetal ovarian somatic cell–like cells (FOSLCs) expressing
Nr5a1
, a representative marker gene of gonadal somatic cells, through the nascent mesoderm, intermediate mesoderm, and coelomic epithelium states. FOSLCs exhibited a transcriptional profile and cellular composition similar to those in embryonic ovarian somatic cells at embryonic day 12.5. When FOSLCs were aggregated with PGCLCs derived from mESCs, the PGCLCs entered meiosis, and subsequent oocyte growth accompanied the development of FOSLC-derived follicles in culture. PGCLC-derived oocytes developing in the FOSLC-derived follicles were capable of fertilization and developed to live offspring. These results demonstrate the reconstitution of functional follicle structures that are fully capable of supporting oocyte production.
CONCLUSION
Our results demonstrate that functional gonadal somatic cells can be induced from mESCs through a faithful differentiation process in culture. The generated material may serve as a useful source to replace embryonic ovarian tissue for in vitro gametogenesis. Furthermore, this system contributes to a better understanding of gonadal somatic cell differentiation and the interactions between oocytes and follicular somatic cells. Because it does not require embryonic gonads, the methodology opens the possibility for application in other mammalian species with fewer ethical and technical concerns. This system will accelerate our understanding of gonadal development and provide an alternative source of gametes for research and reproduction.
Reconstitution of follicle structures, including oocytes, entirely from mouse pluripotent stem cells.
Illustrations on the left show a schematic overview of reconstitution of both FOSLCs and PGCLCs from mESCs. Oocytes in the reconstituted environment gave rise to offspring after fertilization. The right image represents fully grown cumulus-oocyte complexes derived from FOSLCs (red) and PGCLCs (blue).
Oocytes mature in a specialized fluid-filled sac, the ovarian follicle, which provides signals needed for meiosis and germ cell growth. Methods have been developed to generate functional oocytes from pluripotent stem cell–derived primordial germ cell–like cells (PGCLCs) when placed in culture with embryonic ovarian somatic cells. In this study, we developed culture conditions to recreate the stepwise differentiation process from pluripotent cells to fetal ovarian somatic cell–like cells (FOSLCs). When FOSLCs were aggregated with PGCLCs derived from mouse embryonic stem cells, the PGCLCs entered meiosis to generate functional oocytes capable of fertilization and development to live offspring. Generating functional mouse oocytes in a reconstituted ovarian environment provides a method for in vitro oocyte production and follicle generation for a better understanding of mammalian reproduction.
In this study, we demonstrate that the utilization of modeling CV offers a promising new quantitative approach for elucidating charge storage mechanisms in two categories: diffusion-controlled and ...capacitive-controlled processes. Furthermore, we compared the results with Dunn's and Trasatti's methods, highlighting discrepancies and limitations in these approaches. Our research underscores the importance of constructing models that accurately represent the entire CV system, enabling a deeper understanding of charge storage mechanisms. Consequently, our findings pave the way for the advancement of more efficient and effective energy storage technologies.
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•CV data were simulated and compared with conventional relationships.•Highlighting the advantages and limitations of using conventional approaches.•Studying the impact of resistance and CPE exponent on charge storage mechanisms.•Emphasizing the significance of further developing CV models.
As electrochemical energy storage continues to gain importance, researchers have been exploring novel materials and electrode designs to enhance performance. While these innovations have significantly improved the performance of energy storage devices, the specific mechanisms responsible for their success remain unclear. One powerful tool for gaining insights into how modifications to the electrode can enhance cell performance is cyclic voltammetry (CV). However, interpreting CV data can be challenging, and simple analytical relations are often inadequate for accurate assessment. Moreover, different analytical methods can yield conflicting results, leading to confusion within the research community and hindering progress in the field. To address these challenges, our study aims to investigate the contributions of surface and diffusion-controlled processes to charge storage in supercapacitor applications. We will employ conventional methods to examine how these processes can lead to the misinterpretation of CV data and identify the advantages and limitations of different analytical approaches. Our research underscores the importance of developing models that faithfully replicate the system of interest to gain insights into charge storage mechanisms. By identifying these key factors, our findings could pave the way for the development of more efficient and effective energy storage technologies.
Recent clinical and experimental evidence has evoked the concept ofthe gut-brain axis to explain mutual interactions between the central nervous system and gut microbiota that are closely associated ...with the bidirectional effects of inflammatory bowel disease and central nervous system disorders. Despite recent advances in our understanding of neuroimmune interactions, it remains unclear how the gut and brain communicate to maintain gut immune homeostasis, including in the induction and maintenance of peripheral regulatory T cells (pTreg cells), and what environmental cues prompt the host to protect itself from development of inflammatory bowel diseases. Here we report a liver-brain-gut neural arc that ensures the proper differentiation and maintenance of pTreg cells in the gut. The hepatic vagal sensory afferent nerves are responsible for indirectly sensing the gut microenvironment and relaying the sensory inputs to the nucleus tractus solitarius ofthe brainstem, and ultimately to the vagal parasympathetic nerves and enteric neurons. Surgical and chemical perturbation of the vagal sensory afferents at the hepatic afferent level reduced the abundance of colonic pTreg cells; this was attributed to decreased aldehyde dehydrogenase (ALDH) expression and retinoic acid synthesis by intestinal antigen-presenting cells. Activation of muscarinic acetylcholine receptors directly induced ALDH gene expression in both human and mouse colonic antigen-presenting cells, whereas genetic ablation ofthese receptors abolished the stimulation of antigen-presenting cells in vitro. Disruption of left vagal sensory afferents from the liver to the brainstem in mouse models of colitis reduced the colonic pTreg cell pool, resulting in increased susceptibility to colitis. These results demonstrate that the novel vago-vagal liver-brain-gut reflex arc controls the number of pTreg cells and maintains gut homeostasis. Intervention in this autonomic feedback feedforward system could help in the development oftherapeutic strategies to treat or prevent immunological disorders of the gut.
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