Taurine hypomodification underlies mitochondrial tRNATrp-related genetic diseases.

Escherichia coli MnmE and MnmG form a complex (EcMnmEG), generating transfer RNA (tRNA) 5-carboxymethylaminomethyluridine (cmnm5U) modification. Both cmnm5U and equivalent 5-taurinomethyluridine (τm5U, catalyzed by homologous GTPBP3 and MTO1) are found at U34 in several human mitochondrial tRNAs (hmtRNAs). Certain mitochondrial DNA (mtDNA) mutations, including m.3243A > G in tRNALeu(UUR) and m.8344A > G in tRNALys, cause genetic diseases, partially due to τm5U hypomodification. However, whether other mtDNA variants in different tRNAs cause a defect in τm5U biogenesis remains unknown. Here, we purified naturally assembled EcMnmEG from E. coli. Notably, EcMnmEG was able to incorporate both cmnm5U and τm5U into hmtRNATrp (encoded by MT-TW), providing a valuable basis for directly monitoring the effects of mtDNA mutations on U34 modification. In vitro, several clinical hmtRNATrp pathogenic mutations caused U34 hypomodification. A patient harboring an m.5541C > T mutation exhibited hmtRNATrp τm5U hypomodification. Moreover, using mtDNA base editing, we constructed two cell lines carrying m.5532G > A or m.5545C > T mutations, both of which exhibited hmtRNATrp τm5U hypomodification. Taurine supplementation improved mitochondrial translation in patient cells. Our findings describe the third hmtRNA species with mutation-related τm5U-hypomodification and provide new insights into the pathogenesis and intervention strategy for hmtRNATrp-related genetic diseases.

Comparative time-series multi-omics analyses suggest H1.2 involvement in anoxic adaptation and cancer resistance.

The naked mole rat (NMR), Heterocephalus glaber, is known as the longest-lived rodent and is extraordinarily resistant to hypoxia and cancer. Here, both NMR embryonic fibroblasts (NEFs) and their mouse counterparts (MEFs) were subjected to anoxic conditions (0% O2, 5% CO2). A combination of comparative transcriptomics and proteomics was then employed to identify differentially expressed genes (DEGs). Notably, we observed distinct levels of histone H1.2 (encoded by HIST1H1C) accumulation between NEFs and MEFs. Subsequent mechanistic analyses showed that higher H1.2 expression in NEFs was associated with the lower expression of its inhibitor, PARP1. Additionally, we discovered that H1.2 can directly interact with HIF-1α PAS domains, thereby promoting the expression of HIF-1α through facilitating the dimerization with HIF-1ß. The overexpression of H1.2 was also found to trigger autophagy and to suppress the migration of cancer cells, as well as the formation of xenograft tumors, via the NRF2/P62 signaling pathway. Moreover, an engineered H1.2 knock-in mouse model exhibited significantly extended survival in hypoxic conditions (4% O2) and showed a reduced rate of tumor formation. Collectively, our results indicate a potential mechanistic link between H1.2 and the dual phenomena of anoxic adaptation and cancer resistance.

Bioderived Nanoparticles for Cardiac Repair.

Biobased therapy represents a promising strategy for myocardial repair. However, the limitations of using live cells, including the risk of immunogenicity of allogeneic cells and inconsistent therapeutic efficacy of autologous cells together with low stability, result in an unsatisfactory clinical outcomes. Therefore, cell-free strategies for cardiac tissue repair have been proposed as alternative strategies. Cell-free strategies, primarily based on the paracrine effects of cellular therapy, have demonstrated their potential to inhibit apoptosis, reduce inflammation, and promote on-site cell migration and proliferation, as well as angiogenesis, after an infarction and have been explored preclinically and clinically. Among various cell-free modalities, bioderived nanoparticles, including adeno-associated virus (AAV), extracellular vesicles, cell membrane-coated nanoparticles, and exosome-mimetic nanovesicles, have emerged as promising strategies due to their improved biological function and therapeutic effect. The main focus of this review is the development of existing cellular nanoparticles and their fundamental working mechanisms, as well as the challenges and opportunities. The key processes and requirements for cardiac tissue repair are summarized first. Various cellular nanoparticle modalities are further highlighted, together with their advantages and limitations. Finally, we discuss various delivery approaches that offer potential pathways for researchers and clinicians to translate cell-free strategies for cardiac tissue repair into clinical practice.

Evolutionary origin of the chordate nervous system revealed by amphioxus developmental trajectories.

The common ancestor of all vertebrates had a highly sophisticated nervous system, but questions remain about the evolution of vertebrate neural cell types. The amphioxus, a chordate that diverged before the origin of vertebrates, can inform vertebrate evolution. Here we develop and analyse a single-cell RNA-sequencing dataset from seven amphioxus embryo stages to understand chordate cell type evolution and to study vertebrate neural cell type origins. We identified many new amphioxus cell types, including homologues to the vertebrate hypothalamus and neurohypophysis, rooting the evolutionary origin of these structures. On the basis of ancestor-descendant reconstruction of cell trajectories of the amphioxus and other species, we inferred expression dynamics of transcription factor genes throughout embryogenesis and identified three ancient developmental routes forming chordate neurons. We characterized cell specification at the mechanistic level and generated mutant lines to examine the function of five key transcription factors involved in neural specification. Our results show three developmental origins for the vertebrate nervous system: an anterior FoxQ2-dependent mechanism that is deeply conserved in invertebrates, a less-conserved route leading to more posterior neurons in the vertebrate spinal cord and a mechanism for specifying neuromesoderm progenitors that is restricted to chordates. The evolution of neuromesoderm progenitors may have led to a dramatic shift in posterior neural and mesodermal cell fate decisions and the body elongation process in a stem chordate.

Phylogenomics of Afrotherian mammals and improved resolution of extant Paenungulata.

Molecular investigations have gathered a diverse set of mammals-predominantly African natives like elephants, hyraxes, and aardvarks-into a clade known as Afrotheria. Nevertheless, the precise phylogenetic relationships among these species remain contentious. Here, we sourced orthologous markers and ultraconserved elements to discern the interordinal connections among Afrotherian mammals. Our phylogenetic analyses bolster the common origin of Afroinsectiphilia and Paenungulata, and propose Afrosoricida as the closer relative to Macroscelidea rather than Tubulidentata, while also challenging the notion of Sirenia and Hyracoidea as sister taxa. The approximately unbiased test and the gene concordance factor uniformly recognized the alliance of Proboscidea with Hyracoidea as the dominant topology within Paenungulata. Investigation into sites with extremly high phylogenetic signal unveiled their potential to intensify conflicts in the Paenungulata topology. Subsequent exploration suggested that incomplete lineage sorting was predominantly responsible for the observed contentious relationships, whereas introgression exerted a subsidiary influence. The divergence times estimated in our study hint at the Cretaceous-Paleogene (K-Pg) extinction event as a catalyst for Afrotherian diversification. Overall, our findings deliver a tentative but insightful overview of Afrotheria phylogeny and divergence, elucidating these relationships through the lens of phylogenomics.

Improved mammalian family phylogeny using gap-rare multiple sequence alignment: A timetree of extant placentals and marsupials.

The timing of mammalian diversification in relation to the Cretaceous-Paleogene (KPg) mass extinction continues to be a subject of substantial debate. Previous studies have either focused on limited taxonomic samples with available whole-genome data or relied on short sequence alignments coupled with extensive species samples. In the present study, we improved an existing dataset from the landmark study of Meredith et al. (2011) by filling in missing fragments and further generated another dataset containing 120 taxa and 98 exonic markers. Using these two datasets, we then constructed phylogenies for extant mammalian families, providing improved resolution of many conflicting relationships. Moreover, the timetrees generated, which were calibrated using appropriate molecular clock models and multiple fossil records, indicated that the interordinal diversification of placental mammals initiated before the Late Cretaceous period. Additionally, intraordinal diversification of both extant placental and marsupial lineages accelerated after the KPg boundary, supporting the hypothesis that the availability of numerous vacant ecological niches subsequent to the mass extinction event facilitated rapid diversification. Thus, our results support a scenario of placental radiation characterized by both basal cladogenesis and active interordinal divergences spanning from the Late Cretaceous into the Paleogene.

Fluid flow-induced modulation of viability and osteodifferentiation of periodontal ligament stem cell spheroids-on-chip.

Developing physiologically relevant in vitro models for studying periodontitis is crucial for understanding its pathogenesis and developing effective therapeutic strategies. In this study, we aimed to integrate the spheroid culture of periodontal ligament stem cells (PDLSCs) within a spheroid-on-chip microfluidic perfusion platform and to investigate the influence of interstitial fluid flow on morphogenesis, cellular viability, and osteogenic differentiation of PDLSC spheroids. PDLSC spheroids were seeded onto the spheroid-on-chip microfluidic device and cultured under static and flow conditions. Computational analysis demonstrated the translation of fluid flow rates of 1.2 µl min-1 (low-flow) and 7.2 µl min-1 (high-flow) to maximum fluid shear stress of 59 µPa and 360 µPa for low and high-flow conditions, respectively. The spheroid-on-chip microfluidic perfusion platform allowed for modulation of flow conditions leading to larger PDLSC spheroids with improved cellular viability under flow compared to static conditions. Modulation of fluid flow enhanced the osteodifferentiation potential of PDLSC spheroids, demonstrated by significantly enhanced alizarin red staining and alkaline phosphatase expression. Additionally, flow conditions, especially high-flow conditions, exhibited extensive calcium staining across both peripheral and central regions of the spheroids, in contrast to the predominantly peripheral staining observed under static conditions. These findings highlight the importance of fluid flow in shaping the morphological and functional properties of PDLSC spheroids. This work paves the way for future investigations exploring the interactions between PDLSC spheroids, microbial pathogens, and biomaterials within a controlled fluidic environment, offering insights for the development of innovative periodontal therapies, tissue engineering strategies, and regenerative approaches.

Engineering RsDddA as mitochondrial base editor with wide target compatibility and enhanced activity.

Double-stranded DNA-specific cytidine deaminase (DddA) base editors hold great promise for applications in bio-medical research, medicine, and biotechnology. Strict sequence preference on spacing region presents a challenge for DddA editors to reach their full potential. To overcome this sequence-context constraint, we analyzed a protein dataset and identified a novel DddAtox homolog from Ruminococcus sp. AF17-6 (RsDddA). We engineered RsDddA for mitochondrial base editing in a mammalian cell line and demonstrated RsDddA-derived cytosine base editors (RsDdCBE) offered a broadened NC sequence compatibility and exhibited robust editing efficiency. Moreover, our results suggest the average frequencies of mitochondrial genome-wide off-target editing arising from RsDdCBE are comparable to canonical DdCBE and its variants.

Microphysiological Modeling of Gingival Tissues and Host-Material Interactions Using Gingiva-on-Chip.

Gingiva plays a crucial barrier role at the interface of teeth, tooth-supporting structures, microbiome, and external agents. To mimic this complex microenvironment, an in vitro microphysiological platform and biofabricated full-thickness gingival equivalents (gingiva-on-chip) within a vertically stacked microfluidic device is developed. This design allowed long-term and air-liquid interface culture, and host-material interactions under flow conditions. Compared to static cultures, dynamic cultures on-chip enabled the biofabrication of gingival equivalents with stable mucosal matrix, improved epithelial morphogenesis, and barrier features. Additionally, a diseased state with disrupted barrier function representative of gingival/oral mucosal ulcers is modeled. The apical flow feature is utilized to emulate the mechanical action of mouth rinse and integrate the assessment of host-material interactions and transmucosal permeation of oral-care formulations in both healthy and diseased states. Although the gingiva-on-chip cultures have thicker and more mature epithelium, the flow of oral-care formulations induced increased tissue disruption and cytotoxic features compared to static conditions. The realistic emulation of mouth rinsing action facilitated a more physiological assessment of mucosal irritation potential. Overall, this microphysiological system enables biofabrication of human gingiva equivalents in intact and ulcerated states, providing a miniaturized and integrated platform for downstream host-material and host-microbiome applications in gingival and oral mucosa research.

Atherosclerosis: The Involvement of Immunity, Cytokines and Cells in Pathogenesis, and Potential Novel Therapeutics.

As a leading contributor to coronary artery disease (CAD) and stroke, atherosclerosis has become one of the major cardiovascular diseases (CVD) negatively impacting patients worldwide. The endothelial injury is considered to be the initial step of the development of atherosclerosis, resulting in immune cell migration and activation as well as inflammatory factor secretion, which further leads to acute and chronic inflammation. In addition, the inflammation and lipid accumulation at the lesions stimulate specific responses from different types of cells, contributing to the pathological progression of atherosclerosis. As a result, recent studies have focused on using molecular biological approaches such as gene editing and nanotechnology to mediate cellular response during atherosclerotic development for therapeutic purposes. In this review, we systematically discuss inflammatory pathogenesis during the development of atherosclerosis from a cellular level with a focus on the blood cells, including all types of immune cells, together with crucial cells within the blood vessel, such as smooth muscle cells and endothelial cells. In addition, the latest progression of molecular-cellular based therapy for atherosclerosis is also discussed. We hope this review article could be beneficial for the clinical management of atherosclerosis.

Plant-Derived Biomaterials and Their Potential in Cardiac Tissue Repair.

Cardiovascular disease remains the leading cause of mortality worldwide. The inability of cardiac tissue to regenerate after an infarction results in scar tissue formation, leading to cardiac dysfunction. Therefore, cardiac repair has always been a popular research topic. Recent advances in tissue engineering and regenerative medicine offer promising solutions combining stem cells and biomaterials to construct tissue substitutes that could have functions similar to healthy cardiac tissue. Among these biomaterials, plant-derived biomaterials show great promise in supporting cell growth due to their inherent biocompatibility, biodegradability, and mechanical stability. More importantly, plant-derived materials have reduced immunogenic properties compared to popular animal-derived materials (e.g., collagen and gelatin). In addition, they also offer improved wettability compared to synthetic materials. To date, limited literature is available to systemically summarize the progression of plant-derived biomaterials in cardiac tissue repair. Herein, this paper highlights the most common plant-derived biomaterials from both land and marine plants. The beneficial properties of these materials for tissue repair are further discussed. More importantly, the applications of plant-derived biomaterials in cardiac tissue engineering, including tissue-engineered scaffolds, bioink in 3D biofabrication, delivery vehicles, and bioactive molecules, are also summarized using the latest preclinical and clinical examples.

35th International Mammalian Genome Conference: meeting overview.

The 35th International Mammalian Genome Conference (IMGC) was held on July 17-20, 2022 in Vancouver, British Columbia; this conference marked the first time the International Mammalian Genome Society (IMGS) hosted a meeting in Canada. Scientists from around the world participated to share advances in genetics and genomics research across mammalian species. A diverse attendance of pre-doctoral and post-doctoral trainees, young investigators, established researchers, clinicians, bioinformaticians, and computational biologists enjoyed a rich scientific program selected from 88 abstracts in the fields of cancer, conservation genetics, developmental biology, epigenetics, human disease modeling, immunology, infectious diseases, systems genetics, translational biology, and technological advances.

Comparative susceptibility of SARS-CoV-2, SARS-CoV, and MERS-CoV across mammals.

Exploring wild reservoirs of pathogenic viruses is critical for their long-term control and for predicting future pandemic scenarios. Here, a comparative in vitro infection analysis was first performed on 83 cell cultures derived from 55 mammalian species using pseudotyped viruses bearing S proteins from SARS-CoV-2, SARS-CoV, and MERS-CoV. Cell cultures from Thomas's horseshoe bats, king horseshoe bats, green monkeys, and ferrets were found to be highly susceptible to SARS-CoV-2, SARS-CoV, and MERS-CoV pseudotyped viruses. Moreover, five variants (del69-70, D80Y, S98F, T572I, and Q675H), that beside spike receptor-binding domain can significantly alter the host tropism of SARS-CoV-2. An examination of phylogenetic signals of transduction rates revealed that closely related taxa generally have similar susceptibility to MERS-CoV but not to SARS-CoV and SARS-CoV-2 pseudotyped viruses. Additionally, we discovered that the expression of 95 genes, e.g., PZDK1 and APOBEC3, were commonly associated with the transduction rates of SARS-CoV, MERS-CoV, and SARS-CoV-2 pseudotyped viruses. This study provides basic documentation of the susceptibility, variants, and molecules that underlie the cross-species transmission of these coronaviruses.

Development of a novel feeding regime for large scale production of human umbilical cord mesenchymal stem/stromal cells.

Human umbilical cord mesenchymal stem/stromal cells (hUC-MSCs) have attracted significant research interests in regenerative medicine and cell-based therapies due to their minimally invasive isolation procedure, abundant availability, allogenic nature, improved proliferation capacity and tri-lineage differentiation potential. However, the challenge in harvesting a sufficient number of hUC-MSCs through conventional static culture for downstream application hinders the downstream clinical translation of hUC-MSCs. Hence, an alternative culture method that can facilitate large-scale expansion is highly desirable. Herein, we developed a microcarrier-based dynamic culture system to culture hUC-MSCs combined fed-batch mode with medium refreshment to decrease concentrations of metabolic wastes, improve nutrient supplement and reduce the amount of medium used for cell culture. Instead of refreshing medium based on the pre-determined frequency, the replacement and feeding of medium using the novel feeding regime were carried out based on consumption of nutrients (glucose and glutamine) and production of metabolic waste (lactate and ammonia) to maintain a balanced and benign culture microenvironment. The optimal process allowed over 20 folds increase of cell with a maximum cell density at (24.13 ± 0.59) × 105 cells/mL. In addition, no significant alteration of cell surface markers of hUC-MSCs derived from dynamic conditions was observed compared to static conditions. Impressively, over 99.8% of the cellular population showed the desired positive expression of CD73, CD90 and CD105, while less than 0.2% of the population showed undesired negative expression of CD34, CD45 and HLA-DR. More importantly, hUC-MSCs derived from our dynamic culture condition still maintained their trilineage differentiation capacity. Supplementary Information: The online version contains supplementary material available at 10.1007/s10616-022-00523-5.

Manipulation of Electrode Composition for Effective Water Management in Fuel Cells Fed with an Electrically Rechargeable Liquid Fuel.

The liquid fuel cell, with its high energy density and ease of fuel handling, has attracted great attention worldwide. However, its real application is still being greatly hindered by its limited power density. Hence, the recently proposed and demonstrated fuel cell, using an electrically rechargeable liquid fuel (e-fuel), is believed to be a candidate with great potential due to its significant performance advancement. Unlike the conventional alcoholic liquid fuels, the e-fuel possesses excellent reactivity, even on carbon-based materials, which therefore allows the e-fuel cell to achieve superior performance without any noble metal catalysts. However, it is found that, during the cell operation, the water generated at the cathode following the oxygen reduction reaction could lead to a water flooding problem and further limit the cell performance. To address this issue, in this work, by manipulating the cathode composition, a blended binder cathode using both Nafion and polytetrafluoroethylene as binding agents is fabricated and demonstrated its superiority in the fuel cell to achieve an enhanced water management and cell performance. Furthermore, using the developed cathode, a fuel cell stack is designed and fabricated to power a 3D-printed toy car, presenting this system as a promising device feasible for future study and real applications.

DdCBE mediates efficient and inheritable modifications in mouse mitochondrial genome.

Critical mutations of mitochondrial DNA (mtDNA) generally lead to maternally inheritable diseases that affect multiple organs and systems; however, it was difficult to alter mtDNA in mammalian cells to intervene in or cure mitochondrial disorders. Recently, the discovery of DddA-derived cytosine base editor (DdCBE) enabled the precise manipulation of mtDNA. To test its feasibility for in vivo use, we selected several sites in mouse mtDNA as DdCBE targets to resemble the human pathogenic mtDNA G-to-A mutations. The efficiency of DdCBE-mediated mtDNA editing was first screened in mouse Neuro-2A cells and DdCBE pairs with the best performance were chosen for in vivo targeting. Microinjection of the mRNAs of DdCBE halves in the mouse zygotes or 2-cell embryo successfully generated edited founder mice with a base conversion rate ranging from 2.48% to 28.51%. When backcrossed with wild-type male mice, female founders were able to transmit the mutations to their offspring with different mutation loads. Off-target analyses demonstrated a high fidelity for DdCBE-mediated base editing in mouse mtDNA both in vitro and in vivo. Our study demonstrated that the DdCBE is feasible for generation of mtDNA mutation models to facilitate disease study and for potential treatment of mitochondrial disorders.

A Passive Fuel Cell Fed with an Electrically Rechargeable Liquid Fuel.

Passive fuel cells, using diffusion and natural convection for fuel delivery, are regarded as promising candidates for powering portable devices including mobile phones and laptops. However, the performance of passive fuel cells which employ typical liquid alcohol fuels are still limited, which thereby greatly hampered their commercialization progress. Recently, a novel concept named the electrically rechargeable liquid fuel (e-fuel), with its rechargeability, cost-effectiveness, and superior reactivity, has attracted increasing attention. In this study, a passive fuel cell using the liquid e-fuel and the ambient air for electricity production is designed and fabricated. This passive fuel cell is demonstrated to achieve a peak power density of 116.2 mW cm-2 along with a stable operation for over 350 h, exhibiting great prospect for future applications.

Evaluation of a Virus-like Nanoparticle Porcine Circovirus Type-2 (PCV2) Capsid Protein Fused with the Pig Immunoglobulin Fc Fragment as a Novel Vaccine Candidate against PCV2 in Mice.

Porcine circovirus Type 2 (PCV2) is a primary etiological pathogen of post-weaning multi-systemic wasting syndrome (PMWS). The capsid protein of PCV2 is the crucial immunogenic protein which can induce antibody generation and immune responses. However, there is still a lack of efficient PCV2 vaccines with high immunogenicity. In the current study, we developed a novel engineered PCV2 capsid (∆1-41aa)-pFc fusion protein (PCFP), which comprised a truncated capsid protein of PCV2 and a porcine IgG Fc fragment, fused to the capsid protein of PCV2 at the C-terminus. We found that this novel fusion protein could auto-assemble into virus-like nanoparticles with an estimated mean diameter of 22.6 nm, characterized by transmission electron microscopy. Immunization of BALB/c mice with this fusion protein significantly increased the production levels of anti-PCV2-capsid protein antibody in serum. Besides, the virus-like nanoparticles, PCFP was demonstrated to induce efficient cellular immune responses in mice, as evident by the high specific T cell reactivity to the PCFP fusion protein and the high production of the immune cytokines IFN-γ and IL-10 in an ex vivo re-stimulation system. Collectively, these findings demonstrate that the PCV2 truncated capsid subunit Fc-fusion protein can induce both cellular and humoral immune responses, and it displays great application potential.

A Review of Biomechanics Analysis of the Umbilical-Placenta System With Regards to Diseases.

Placenta is an important organ that is crucial for both fetal and maternal health. Abnormalities of the placenta, such as during intrauterine growth restriction (IUGR) and pre-eclampsia (PE) are common, and an improved understanding of these diseases is needed to improve medical care. Biomechanics analysis of the placenta is an under-explored area of investigation, which has demonstrated usefulness in contributing to our understanding of the placenta physiology. In this review, we introduce fundamental biomechanics concepts and discuss the findings of biomechanical analysis of the placenta and umbilical cord, including both tissue biomechanics and biofluid mechanics. The biomechanics of placenta ultrasound elastography and its potential in improving clinical detection of placenta diseases are also discussed. Finally, potential future work is listed.