Biology subjects

Yamazaki, K.

Publications and source records attributed to Yamazaki, K..

16 recordsLinked to original sources

bioRxiv2026

BRCA2 loss triggers a downward spiral of genomic instability via ROS-dependent metabolic collapse

BRCA2 plays a central role in maintaining genome integrity through homologous recombination and replication-fork protection, yet the compensatory networks sustaining BRCA2-deficient cells remain unclear. Here we show BRCA2 enforces a homeostatic mechanism aligning mitochondrial respiration with DNA repair capacity in both cancer and non-cancer contexts. Genome-wide CRISPR screening identified glutathione metabolism and base-excision repair as the key compensatory networks sustaining BRCA2-deficient cells by detoxifying mitochondria-derived reactive oxygen species. BRCA2 loss provokes an acute mitochondrial ROS surge, causing 8-oxoguanine accumulation and a systemic metabolic crisis marked by NAD+ and glutathione depletion. PARP inhibitor targets DNA replication vulnerabilities, increasing the cellular requirement for BRCA2. The resulting oxidative burden primes cells for TP53-dependent apoptosis in G1 during olaparib treatment, which extends cytotoxicity beyond canonical S-phase stress. These findings indicate BRCA2 prevents metabolic flux from outpacing repair capacity, providing a rationale for combining PARP inhibition with redox modulation to enhance efficacy and overcome resistance. HighlightsO_LIAcute BRCA2 loss induces ROS and mitochondrial dysfunction creating a metabolic scar C_LIO_LIOxidative lesions drive PARP hyperactivation and precipitate a cellular NAD crisis C_LIO_LIPARP inhibitors provoke TP53-dependent apoptosis in G1 beyond replication stress in S phase C_LIO_LIGlutathione deficiency exacerbates bone marrow failure under BRCA2 depletion C_LIO_LIBRCA2 tightly couples mitochondrial redox homeostasis to genomic maintenance C_LI

cell biology↗

bioRxiv2026

High-throughput CRISPR live-cell imaging of low-frequency chromosomal events quantifies the latent efficiency of chromosome engineering

Abstract/SummaryQuantifying low-frequency chromosomal alterations in living cell populations at early stages is essential in many fields including cancer studies and chromosome engineering, yet selection-based readouts impose delays and can lose fragile positives before readout, biasing frequency estimates; CRISPR imaging rarely reports detection limits at 10^-4. Here, we developed High-throughput CRISPR Imaging (Hi-CRI), integrating engineered dCas9-sgRNA ribonucleoprotein (RNP) labeling, suppression of nonspecific aggregates via metabolic modulation and protease treatment, high-speed volumetric imaging by oblique plane microscopy, GPU-accelerated image analysis, and an explicit error-controlled detection-limit framework. Using per-cell signal-to-noise ratio calling, Hi-CRI achieves a 0.01% detection limit for target-positive cell fractions. In microcell-mediated chromosome transfer of a mouse artificial chromosome (MAC) into HT1080 recipients, Hi-CRI measured 0.03% MAC-positive cells among 184,235 recipients at day 1 post-fusion, versus 0.0007% by antibiotic-selection-based clonogenic assay at day 8 post-fusion, consistent with substantial loss before readout (pre-readout attrition). Hi-CRI enables viability-preserving, selection-independent quantification of low-frequency chromosomal states. TeaserRare chromosome events can be counted in living cells by high-throughput CRISPR imaging before selection hides them.

bioengineering↗

bioRxiv2026

The GspCD-dependent type II secretion system drives necrotizing soft tissue infection by Aeromonas hydrophila

Necrotizing soft tissue infections (NSTIs) are fulminant bacterial diseases characterized by rapid tissue destruction, systemic deterioration, and high mortality. Aeromonas hydrophila is an important causative agent of NSTIs, but the system-level bacterial mechanisms that coordinate tissue destruction, in vivo expansion, dissemination, and host lethality remain incompletely understood. Here, we investigated the contribution of the GspCD-dependent type II secretion system (T2SS) to A. hydrophila pathogenesis using transposon mutants, extracellular protein analyses, and a mouse NSTI model. Mutants carrying transposon insertions in gspD and gspC showed defective secretion of a FLAG-tagged truncated AerA construct and markedly reduced hemolytic activity in culture supernatants. Comparative analysis of extracellular proteins further showed that disruption of gspC altered the extracellular protein landscape, with reduced abundance of multiple known or predicted virulence-associated factors, including AerA, Ahh, lipase, and metalloprotease. In the mouse NSTI model, both mutants exhibited attenuated virulence, including reduced serum markers of tissue injury, less severe histopathological damage, impaired in vivo expansion and dissemination, and decreased lethality. These defects were more pronounced in the gspC mutant than in the gspD mutant. Together, these findings show that the GspCD-dependent T2SS functions as a coordinated extracellular secretion system that drives tissue destruction, in vivo expansion, dissemination, and lethal outcome during A. hydrophila NSTI. IMPORTANCENecrotizing soft tissue infections (NSTIs) are rapidly progressive, life-threatening bacterial infections, and Aeromonas hydrophila is an important causative agent. Here, we show that the GspCD-dependent type II secretion system (T2SS) drives A. hydrophila virulence in a murine NSTI model. Transposon mutants in gspC or gspD exhibited impaired extracellular protein secretion, reduced hemolytic activity, attenuated tissue damage, decreased bacterial proliferation and dissemination, and markedly reduced lethality. Comparative analysis further indicated that T2SS disruption alters the extracellular virulence landscape rather than affecting a single toxin alone. These findings provide in vivo evidence that coordinated T2SS-dependent secretion is a central determinant of severe A. hydrophila soft tissue infection.

microbiology↗

bioRxiv2026

Leveraging archaeological specimens to investigate failed invasions: A case study on Okhotsk pigs, northern Japan

Invasive species pose a major threat to biodiversity, yet our understanding of failed invasions/translocations, instances where alien/introduced species fail to establish, remains limited. Investigating the factors behind failed invasions is critical for improving prevention and management strategies for modern biological invasions. Here, we propose a novel framework that utilizes archaeological archives to uncover evidence of failed invasions. We estimated the biological and ecological factors contributing to the failed invasion of pigs from later prehistory to recent times (299 cal BC to 1900 AD) on Rebun Island in far northern Japan by synthesizing the evidence obtained from stable isotopes, zooarchaeology, and historical documents. Despite the anthropogenic introductions of pigs into Rebun Island, pigs did not establish a feral population and disappeared after ca. 1200 AD. We identified reduced propagule pressure, abiotic resistance due to the cold climate, and decreased resources as the three key factors that contributed to the disappearance of pigs. Pigs are one of the most widespread invasive species globally, and this study represents a novel approach to studying failed invasions using archaeological data, which aligns with the framework of conservation paleobiology.

ecology↗

bioRxiv2026

Enzyme activity as an actionable axis for small-molecule precision oncology

Current precision oncology--molecular targeted therapies and immunotherapies--relies on genomic or expressed biomarkers, yet most cancer patients remain ineligible for these treatments. Here, we establish enzyme activity as an actionable and orthogonal axis for precision cancer medicine. Strategic activity-based screening of mouse organs and human clinical specimens with a panel of enzyme-reactive fluorescence probes identified {beta}-galactosidase 1 (GLB1) and {beta}-hexosaminidases (HEX) as broadly elevated tumor-selective biomarkers. Leveraging these activities, we developed 7-ethyl-10-hydroxycamptothecin (SN38)-based GLB1-and HEX-reactive prodrugs. These prodrugs exhibited dramatically reduced systemic toxicities and improved therapeutic windows, compared to a clinically used SN38-based prodrug, irinotecan (CPT-11). Both prodrugs demonstrated activity-dependent therapeutic efficacy, affording a dramatic reduction of tumor volumes across multiple in vivo models, including a subcutaneous patient-derived xenograft (PDX) of lung squamous cell carcinoma that lacked genetic alterations targeted by current precision medicine. Furthermore, this strategy is broadly applicable across various cytotoxic payloads, establishing a generalizable platform for small-molecule precision medicines. Our results define an enzyme-targeting paradigm for precision oncology, in which fluorescence probes serve as companion diagnostic tools to guide development and selection of appropriately targeted prodrugs, which are expected to provide safer and more efficacious treatment options for cancer patients with elevated enzyme activities.

cancer biology↗

bioRxiv2025

Phenotypic Characterization of Signature-Tagged Mutants Identifies Physiological Determinants of Vibrio vulnificus Fitness

Vibrio vulnificus is an opportunistic marine pathogen that causes severe wound-associated and systemic infections. Following entry into the host, the bacterium must rapidly adapt to host-associated stresses that differ substantially from those encountered in aquatic environments. However, the physiological functions supporting bacterial fitness during infection remain incompletely understood. Previously, we applied signature-tagged mutagenesis (STM) to identify genes required for V. vulnificus survival during host infection, revealing numerous loci that did not correspond to classical toxin-encoding genes. In the present study, we extended this genome-wide screen by linking STM-identified mutations to observable fitness-related phenotypes. Functional annotation revealed enrichment of genes associated with chemotaxis, flagellar motility, regulation, metabolism, and poorly characterized functions. Phenotypic analyses showed that many STM-derived mutants exhibited defects in swimming motility and altered colony surface properties. Bioluminescence imaging further revealed distinct patterns of impaired persistence and dissemination within host tissues, while several mutants displayed increased susceptibility to phagocytic stress in an HL-60-derived neutrophil model. Notably, some regulatory mutants affecting global signaling pathways exhibited impaired tissue dissemination despite retaining resistance to phagocytic stress, indicating the presence of fitness determinants that operate independently of classical surface-associated or cytotoxic traits. Together, these findings demonstrate that V. vulnificus fitness during infection depends on diverse physiological pathways beyond classical virulence factors, highlighting the value of phenotype-centered analyses for understanding bacterial adaptation in host-associated environments. ImportanceVibrio vulnificus causes rapidly progressive wound infections and septicemia, yet the bacterial functions that support fitness within host environments remain incompletely defined. While substantial effort has focused on canonical virulence factors and regulation, increasing evidence suggests that successful infection also depends on broader physiological adaptation. In this study, we link signature-tagged mutagenesis with systematic phenotypic analyses to define physiological determinants of V. vulnificus fitness during host-associated infection. Our results demonstrate that genes involved in motility, regulatory signaling, metabolism, and stress tolerance collectively shape bacterial persistence and dissemination in host tissues. Notably, we identify regulatory and metabolic determinants that influence fitness independently of classical surface-associated or cytotoxic traits, highlighting noncanonical pathways that contribute to pathogenic success. By integrating genome-wide screening with phenotype-centered analyses, this work advances understanding of how physiological adaptation underpins V. vulnificus infection and provides a framework for studying bacterial fitness alongside established concepts of bacterial virulence.

microbiology↗

bioRxiv2025

Nutrient Acquisition Drives Edwardsiella tarda Pathogenesis in Necrotizing Soft Tissue Infection

Necrotizing soft tissue infections (NSTIs) are rapidly progressive and life-threatening diseases caused by diverse bacterial pathogens. While classical virulence factors such as toxins and secretion systems have been extensively characterized, the role of metabolic fitness in supporting bacterial survival within the nutrient-restricted host environment remains underexplored. Edwardsiella tarda, a human-pathogenic bacterium implicated in NSTIs, represents an emerging model for studying non-canonical pathogenic strategies. Here, we employed transposon-directed insertion site sequencing (TraDIS) to identify genes critical for E. tarda survival in a murine soft tissue infection model. A genome-wide screen revealed 41 genes significantly depleted during the infection, including those involved in iron and zinc acquisition (fetB, zupT), vitamin biosynthesis (pdxK, cobA), and polyamine metabolism (speB). Functional assays using defined minimal media demonstrated that supplementation with vitamin B6 or putrescine enhanced bacterial growth, validating their contribution to fitness under nutrient-limited conditions. Our findings indicate that E. tarda pathogenesis is driven not solely by classical virulence factors but also by its ability to acquire essential nutrients and adapt metabolically to host-imposed nutritional stress. This study provides the first genome-wide fitness map for E. tarda during soft tissue infection and reveals new targets for therapeutic intervention that disrupt nutrient acquisition systems. These results also emphasize the broader relevance of metabolic adaptation as a determinant of virulence in invasive bacterial infections. IMPORTANCENecrotizing soft tissue infections (NSTIs) are severe, rapidly progressing bacterial infections with high morbidity and mortality. Although classical virulence factors such as toxins have been widely studied, much less is known about how pathogens adapt metabolically to survive within the nutrient-restricted environment in host tissues. This study uses Edwardsiella tarda, an emerging NSTI pathogen, as a model to identify genes required for in vivo fitness using transposon insertion sequencing (TraDIS). By revealing the critical roles of nutrient acquisition and metabolic adaptation, rather than toxin production alone, this work challenges conventional paradigms of bacterial virulence. Our findings suggest that targeting bacterial nutrient acquisition pathways may offer a novel therapeutic approach to control invasive infections. Furthermore, this study provides the first genome-wide fitness map of E. tarda during soft tissue infection, offering a valuable resource for future research into polymicrobial wound infections and host-pathogen nutrient competition.

microbiology↗

bioRxiv2025

The generation of viable, structurally integrated human-mouse chimaeras through enhanced hPSCs proliferation

The generation of human organs in animals through blastocyst complementation offers a promising solution to the shortage of transplantable organs. While human pluripotent stem cells (hPSCs) can contribute to interspecies chimaeric embryos when injected into preimplantation embryos of mice, pigs, or monkeys, their integration is often limited due to low chimaerism and segregation from host tissues, significantly impeding progress toward exogenic organ generation. Here, we demonstrate that co-overexpression of the anti-apoptotic gene BCL2 and the proto-oncogene MYCL, along with various cell cycle regulators significantly enhances human cell chimaerism by promoting cell proliferation. This strategy facilitates the generation of viable mouse pups containing hPSC-derived tissues without tumorigenesis. scRNA-seq analysis revealed that hPSCs already exit pluripotent by early post-implantation stage yet hPSCs with enhanced proliferation were able to integrate effectively into the cardiomyocytes and vasculature of both embryonic and extraembryonic tissues with gene expression profiles reflecting their structural integration. These findings highlight the critical role of cell cycle regulation in overcoming xenogeneic barriers. Our findings offer new insights into strategies for enhancing interspecies organogenesis and advancing the field of regenerative medicine. HighlightO_LIEnhancing hPSC proliferation increases human cell contribution in interspecies chimaeras C_LIO_LIAchieving the generation of viable human-mouse chimaeras without tumour formation C_LIO_LIhPSCs in post-implantation mouse epiblast exit pluripotency but retain the capacity to integrate into mouse embryogenesis C_LIO_LIhPSCs derivatives integrate into vasculature and cardiac tissues with lineage-matched transcriptional profiles C_LI

developmental biology↗

bioRxiv2023

Homologous recombination contributes to the repair of acetaldehyde-induced DNA damages.

Acetaldehyde, a chemical that can cause DNA damage and contribute to cancer, is prevalently present in our environment, e.g., in alcohol, tobacco, and food. Although aldehyde potentially promotes crosslinking reaction among biological substances including DNA, RNA, and proteins, it remains unclear what types of DNA damage are caused by acetaldehyde and how they are repaired. In this study, we examined acetaldehyde sensitivity of DNA damage-deficient cells established from human TK6 cell line. Among the mutants, mismatch repair mutants did not show a hypersensitivity to acetaldehyde, while cells deficient in base and nucleotide excision repair pathways increased its sensitivity. We found a delayed repair and hypersensitivity in homologous recombination (HR)-deficient cells but not in non-homologous end joining-deficient cells after acetaldehyde treatment. By analyzing the formation of acetaldehyde-induced RAD51 foci, which represent HR intermediates, HR-deficient cells, but not NHEJ, exhibits delayed repair of acetaldehyde-induced DNA damages, compared with wild-type. These results suggest that acetaldehyde causes complex DNA damages that requires various types of repair pathways. Interestingly, mutants deficient in TDP1 and TDP2, which are involved in the removal of protein adducts from DNA ends, exhibited hypersensitivity to acetaldehyde. the acetaldehyde sensitivity of the TDP1-/-/RAD54-/- double mutant was similar to that of each single mutant. This epistatic relationship between TDP1 and RAD54 suggests that that the removal of protein-DNA adducts generated by acetaldehyde needs to be removed for efficient repair by HR. Our study would help understand the molecular mechanism of genotoxic and mutagenic effects of acetaldehyde.

molecular biology↗

bioRxiv2023

The ABCF proteins in Escherichia coli individually alleviate nascent peptide-induced noncanonical translations.

Organisms possess a wide variety of proteins with a diverse repertoire of amino acid sequences, and their synthesis relies on the ribosome. Empirical observations have led to the misconception that ribosomes are robust protein factories, but in reality, they have several weaknesses. For instance, ribosomes stall during the translation of the proline-rich sequences, but the translation elongation factor EF-P assists in synthesizing proteins containing the poly-proline sequences. Thus, living organisms have evolved to expand the translation capability of ribosomes through the acquisition of translation elongation factors, enabling the synthesis of diverse proteins. In this study, we have revealed that Escherichia coli ATP-Binding Cassette family-F (ABCF) proteins, YheS, YbiT, EttA and Uup, individually cope with various noncanonical translations induced by nascent peptide sequences within the exit tunnel of the ribosome. The correspondence between noncanonical translations and ABCFs was YheS for the translational arrest by nascent SecM, YbiT for poly-basic sequence-dependent ribosome stalling and poly-acidic sequence-dependent intrinsic ribosome destabilization (IRD), EttA for IRD at the early stage of elongation, and Uup for poly-proline-dependent stalling. Our results suggest that the ATP hydrolysis-coupled structural rearrangement and interdomain linker sequence between the two nucleotide-binding domains play crucial roles in alleviating the noncanonical translations. Our study highlights a new aspect of ABCF proteins to reduce the potential risks that are encoded within the nascent peptide sequences. Significance statementProteins, that constitute living organisms, exhibit a diverse range of amino acid sequences. However, it has become evident that ribosomes have difficulties in synthesizing certain amino acid sequences, including the poly-basic, poly-acidic, and poly-proline sequences. The mechanisms underlying the expression of proteins with such challenging sequences remain largely elusive. In this study, we have unveiled that translation factor ABCF proteins in Escherichia coli promote various kinds of problematic amino acid sequences that inhibit efficient translation. Through the actions of translation elongation factors including the ABCF proteins, the translation system acquires robustness in synthesizing a vast repertoire of amino acid sequences.

biochemistry↗

bioRxiv2023

Genome analysis of the Jomon dogs reveals the oldest domestic dog lineage in Eastern Eurasia

Dog is the oldest domesticated animal that established close relationships with humans. Due to its ancient origin, when, where, and whether a single or dual domestication event occurred is still under debate. The dogs in the Jomon period (Jomon dogs) in the Japanese archipelago had little change in morphology from 10,000 to 3,000 years ago. Therefore, we expected that the ancient genome of the Jomon dogs would provide a clue to reveal the characteristics of the ancient East Asian dogs. Here, we have sequenced the genomes of three 6000-year-old Jomon dogs, one 3000-4000-year-old Jomon dog, and four late 8th century dogs excavated in Japan. Our analyses suggest that the Jomon dogs are a distinct lineage from the previously known ancient dogs and are one of the oldest among the dogs in East Eurasian lineages. In addition, the genome of the Jomon dogs contained 9.5% of the genome of Japanese wolf ancestry due to a single introgression event. We estimated the proportion of the Jomon dog lineage genome in the genomes of dogs, which indicates that the genomic composition derived from the Jomon dog lineage is one of the major sources of modern dog genomes. Furthermore, we estimated the early admixture events of dogs in East Eurasia by analyzing the ancient genomes of the Jomon dogs. Due to the admixture events, the Jomon dog-derived genome has been one of the genomic sources of a wide range of modern dogs.

evolutionary biology↗

bioRxiv2023

A jump-driven self-exciting stochastic fish migration model and its fisheries applications

We introduce a stochastic continuous-time model via a self-exciting process with jumps to describe a seasonal migration event of diadromous fish. The dynamics of the stored population at a point in a river, waiting for their upward migration, increases by the inflow from the downstream/ocean and decreases by the outflow due to their upstream migration. The inflow is assumed to occur at a constant rate until an Erlang-distributed termination time. The outflow is modeled by a self-exciting jump process to incorporate the flocking and social interactions in fish migration. Harvested cases are also studied for fisheries applications. We derive the backward Kolmogorov equations and the associated finite-difference method to compute various performance indices including the mean migration period and harvested populations. Detailed numerical and sensitivity analysis are conducted to study the spring upstream migration of the diadromous Ayu Plecoglossus altivelis altivelis.

ecology↗

bioRxiv2020

Centriole and PCM cooperatively recruit CEP192 to spindle poles to promote bipolar spindle assembly

The pericentriolar material (PCM) that accumulates around the centriole expands during mitosis and nucleates microtubules. While centrosomes facilitate bipolar spindle formation, the individual functions of the centriole and PCM in mitosis remain elusive. Herein, we show the redundant roles of the centriole and PCM in bipolar spindle formation in human cells. Upon depletion of the PCM scaffold components, pericentrin and CDK5RAP2, centrioles remained able to recruit CEP192 onto their walls, which was sufficient for bipolar spindle formation. In contrast, through centriole removal, we found that pericentrin and CDK5RAP2 recruited CEP192 at the acentriolar spindle pole and facilitated bipolar spindle formation in mitotic cells with one centrosome. Furthermore, the chemical perturbation of polo-like kinase 1, a critical kinase for PCM assembly, efficiently suppressed the proliferation of various cancer cell lines from which centrioles were removed. Overall, these data suggest that the centriole and PCM cooperatively recruit CEP192 to spindle poles and facilitate bipolar spindle formation in human cells.

cell biology↗

bioRxiv2020

A comprehensive framework for handling location error in animal tracking data

Animal tracking data are being collected more frequently, in greater detail, and on smaller taxa than ever before. These data hold the promise to increase the relevance of animal movement for understanding ecological processes, but this potential will only be fully realized if their accompanying location error is properly addressed. Historically, coarsely-sampled movement data have proved invaluable for understanding large scale processes (e.g., home range, habitat selection, etc.), but modern fine-scale data promise to unlock far more ecological information. While GPS location error can often be ignored in coarsely sampled data, fine-scale data require more care, and tools to do this have not kept pace. Current approaches to dealing with location error largely fall into two categories--either discarding the least accurate location estimates prior to analysis or simultaneously fitting movement and error parameters in a hidden-state model. In some cases these approaches can provide a level of correction, but they have known limitations, and in some cases they can be worse than doing nothing. Here, we provide a general framework to account for location error in the analysis of triangulated and trilatcralizcd animal tracking data, which includes GPS, Argos Doppler-shift, triangulated VHF, trilatcralized acoustic and cellular location data. We apply our error-modelselection framework to 190 GPS, cellular, and acoustic devices representing 27 models from 14 manufacturers. Collectively, these devices were used to track a wide range of taxa comprising birds, fish, reptiles, and mammals of different sizes and with different behaviors, in urban, suburban, and wild settings. In almost half of the tested device models, error-model selection was necessary to obtain the best performing error model, and in almost a quarter of tested device models, the reported DOP values were actually misinformative. Then, using empirical tracking data from multiple species, we provide an overview of modern, error-informed movement analyses, including continuous-time path reconstruction, home-range distribution, home-range overlap, speed, and distance estimation. Adding to these techniques, we introduce new error-informed estimators for outlier detection and autocorrelation visualization. Because error-induced biases depend on many factors--sampling schedule, movement characteristics, tracking device, habitat, etc.--differential bias can easily confound biological inference and lead researchers to draw false conclusions. We demonstrate how error-informed analyses on calibrated tracking data can provide more accurate estimates are that are insensitive to location error, and allow researchers to use all of their data.

ecology↗

bioRxiv2020

In vivo recellularization of xenogeneic vascular grafts decellularized with high hydrostatic pressure method in a porcine carotid arterial interpose model

Autologous vascular grafts are widely used in revascularization surgeries for small caliber targets. However, the availability of autologous conduits might be limited due to prior surgeries or the quality of vessels. Xenogeneic decellularized vascular grafts from animals potentially substitute for autologous vascular grafts. Decellularization with high hydrostatic pressure (HHP) is reported to highly preserve extracellular matrix (ECM) which would be feasible for recellularization and vascular remodeling after implantation. In the present study, we conducted xenogeneic implantation of HHP-decellularized bovine vascular grafts from dorsalis pedis arteries to porcine carotid arteries then evaluated graft patency, ECM preservation and recellularization. Surgical procedure not to damage luminal surface of the grafts from drying significantly increased the graft patency at 4 weeks after implantation (P = 0.0079). After the technical improvement, all grafts (N = 5) were patent with mild stenosis due to intimal hyperplasia at 4 weeks after implantation. Neither aneurysmal change nor massive thrombosis was observed even without administration of anticoagulants nor anti-platelet agents. Elastica van Gieson and Sirius-red stainings revealed fair preservation of ECM proteins including elastin and collagen after implantation. Luminal surface of grafts was thoroughly covered with von Willebrand factor-positive endothelium. Scanning electron microscopy on luminal surface of implanted grafts exhibited cobblestone-like endothelial cell layer which is similar to native vascular endothelium. Recellularization of tunica media with alpha-smooth muscle actin-positive smooth muscle cells was partly observed. Thus, we confirmed that HHP-decellularized grafts are feasible for xenogeneic implantation accompanied by recellularization by recipient cells.

bioengineering↗

bioRxiv2018

Magnesium suppresses defects in the formation of 70S ribosomes as well as in sporulation caused by lack of several individual ribosomal proteins.

Individually, the ribosomal proteins L1, L23, L36 and S6 are not essential for cell proliferation of B. subtilis, but the absence of any one of these ribosomal proteins causes a defect in the formation of the 70S ribosomes and a reduced growth rate. In mutant strains individually lacking these ribosomal proteins, the cellular Mg2+ content was significantly reduced. The deletion of YhdP, an exporter of Mg2+, and overexpression of MgtE, the main importer of Mg2+, increased the cellular Mg2+ content and restored the formation of 70S ribosomes in these mutants. The increase in the cellular Mg2+ content improved the growth rate of the {Delta}rplA (L1) and the {Delta}rplW (L23) mutant but did not restore those of the {Delta}rpmJ (L36) and the {Delta}rpsF (S6) mutants. The lack of L1 caused a decrease in the production of Spo0A, the master regulator of sporulation, resulting in a decreased sporulation frequency. However, deletion of yhdP and overexpression of mgtE increased the production of Spo0A and partially restored the sporulation frequency in the {Delta}rplA (L1) mutant. These results indicate that Mg2+ can partly complement the function of several ribosomal proteins, probably by stabilizing the conformation of the ribosome.\n\nIMPORTANCEWe previously reported that an increase in the cellular Mg2+ content can suppress defects in 70S ribosome formation and growth rate caused by the absence of ribosomal protein L34. In the present study, we demonstrated that even in mutants lacking individual ribosomal proteins other than L34 (L1, L23, L36 and S6), an increase in the cellular Mg2+ content could restore the 70S ribosome formation. Moreover, the defect in sporulation caused by the absence of L1 was also suppressed by an increase in the cellular Mg2+ content. These findings indicate that at least part of the function of these ribosomal proteins can be complemented by Mg2+, which is essential for all living cells.

genetics↗