Biology subjects

Matsumoto, Y.

Publications and source records attributed to Matsumoto, Y..

At least 19 recordsLinked to original sources

bioRxiv2026

Determination of effective meropenem and gentamicin doses in a silkworm infection model using a clinical Klebsiella aerogenes isolate

Klebsiella aerogenes, a member of the Enterobacteriaceae, is a causative agent of healthcare-associated infections, and outbreaks caused by drug-resistant K. aerogenes have been reported worldwide. The range of antimicrobial agents available for treating infections caused by carbapenem-resistant K. aerogenes is limited. While in vivo animal experiments using clinical K. aerogenes isolates to evaluate antimicrobial therapy could facilitate selection of the most effective treatment, conducting infection experiments involving large numbers of mammals such as mice is challenging due to ethical concerns related to animal welfare. Silkworms are invertebrates increasingly used as experimental models for infectious disease research to evaluate antimicrobial efficacy. In this study, we aimed to establish a silkworm infection model using a clinical K. aerogenes isolate to evaluate its utility for determining effective antimicrobial doses. K. aerogenes strains were isolated from a patient at a Japanese hospital, and a silkworm infection model was established using the clinical isolate. The non-metallo-beta-lactamase-producing strain K. aerogenes TUM25562, isolated from a patient with a complicated urinary tract infection, was susceptible to meropenem (MEPM) and gentamicin (GM) in vitro. During treatment, additional isolates with increased resistance to MEPM and subsequently to both MEPM and GM emerged. K. aerogenes TUM25562 caused dose-dependent mortality in silkworms. Treatment with clinically equivalent weight-based doses of MEPM or GM did not cure the infected silkworms. The median effective (ED50) doses of MEPM and GM were therefore investigated using the silkworm infection model. Administration of higher doses corresponding to four times the ED50 significantly prolonged the survival of infected silkworms. These results suggest that a silkworm infection model using clinical K. aerogenes isolates may provide a practical approach for evaluating antimicrobial efficacy and determining effective antimicrobial doses.

microbiology↗

bioRxiv2026

Ire1-triggered hxl1 mRNA splicing coordinates stress tolerance and virulence in the pathogenic fungus Trichosporon asahii

The pathogenic fungus Trichosporon asahii causes severe mycoses in immunocompromised hosts, such as neutropenic patients. In Cryptococcus neoformans, the unfolded protein response (UPR) sensor Ire1 induces hxl1 mRNA splicing and contributes to stress responses and virulence. The function of Ire1-triggered hxl1 mRNA splicing in stress tolerance and virulence of T. asahii, however, remains unclear. Here, we demonstrated that ire1- and hxl1 gene-deficient T. asahii mutants are sensitive to dithiothreitol (DTT), an inducer of endoplasmic reticulum stress, and exhibit reduced virulence in a silkworm infection model. DTT treatment induced hxl1 mRNA splicing in the wild-type strain, whereas ire1 gene-deficient mutants did not undergo hxl1 mRNA splicing. The ire1 gene-deficient mutants were more sensitive than the parent strain to DTT, H2O2, Congo red, and SDS, and showed reduced virulence in silkworms. Similarly, hxl1 gene-deficient mutants exhibited increased sensitivity to these stressors and reduced virulence. Both the ire1 gene-deficient and hxl1 gene-deficient mutants showed decreased expression of reactive oxygen species-detoxifying related genes CAT2, SOD1, and SOD2, compared with the parent strain. Together, these findings suggest that Ire1-triggered hxl1 mRNA splicing contributes to stress resistance and virulence in T. asahii.

microbiology↗

bioRxiv2026

Acquisition of Stickland-metabolizing bacteria during infancy prevents Clostridium botulinum infection

Infant botulism is caused by intestinal colonization with Clostridium botulinum, whereas healthy adults are resistant. Although the gut microbiota has long been implicated in protection against C. botulinum, its bacterial basis has remained unknown. Here, we show that specific amino acid-metabolizing bacteria confer resistance to C. botulinum colonization through nutrient competition. Longitudinally collected human infant microbiotas exhibited a transition from susceptibility to resistance after transplantation into germ-free mice. 5-Aminovalerate marked the resistant microbiota, implicating Stickland metabolism. Resistant microbiotas were enriched in Stickland-metabolizing Clostridia, including Clostridioides difficile. Metabolomics revealed overlapping amino acid utilization, and C. difficile suppressed C. botulinum expansion through amino acid competition. These findings demonstrate that acquisition of Stickland-metabolizing Clostridia during infancy prevents C. botulinum infection through competition for shared amino-acid-dependent nutritional niches.

microbiology↗

bioRxiv2026

Evolutionary analysis of V protein pseudogenization in an RNA editing-deficient paramyxovirus

In most paramyxoviruses, RNA editing in the P gene enables expression of the V protein. Human parainfluenza virus type 1 (HPIV-1) differs from most paramyxoviruses in that it lacks RNA editing and does not produce a functional V protein, although its genome retains sequences corresponding to the ancestral V reading frame. Here, we analyzed all HPIV-1 genome sequences available in the NCBI GenBank database to assess the evolutionary state of this V protein-specific region. Using Sendai virus (SeV) as a closely related reference with an identical P gene length, we defined a pseudo-V reading frame by virtually inserting a single nucleotide at the conserved RNA editing site. In this pseudo-V frame, HPIV-1 showed a marked excess of stop codons within the 253-amino-acid region corresponding to the post-editing sequence, far exceeding expectations under random codon usage. This pattern was not observed in other viral genes analyzed under the same definition, nor in SeV, nor was it reproduced by in silico evolutionary simulations under constraints preserving the primary open reading frame. These results are consistent with a virus-specific evolutionary trajectory following the loss of RNA editing, rather than with generic coding constraints acting on overlapping reading frames.

evolutionary biology↗

bioRxiv2026

Distinct virus-specific regulation of RNA synthesis across genome segments by thogotovirus polymerases: insights from Oz virus and Dhori virus

Thogotoviruses are a group of tick-borne, six-segmented, negative-sense single-stranded RNA viruses. These viruses encode an RNA-dependent RNA polymerase that recognizes promoter sequences located at the genomic termini to initiate RNA synthesis. The 5' and 3' ends of the genome bind to the polymerase and function as a promoter. Outside the catalytic center, they base-pair with each other to form a double-stranded RNA structure. This structure is referred to as the distal duplex and plays an important role in RNA synthesis. In this study, we investigated how the RNA sequence of the distal duplex influences polymerase activity using minigenome systems of two thogotoviruses, Oz virus (OZV) and Dhori virus (DHOV). Each virus exhibits distinct activities among its six segments. In OZV, one determinant of these differences is the base pair at positions 5'12 and 3'11 within the distal duplex, where promoter activity varies depending on whether the base pair is G:C or A:U. In contrast, the DHOV polymerase is not affected by this difference. These results indicate that, even within the genus Thogotovirus, viruses differ in whether they possess a mechanism that modulates promoter activity based on subtle sequence differences within the distal duplex. Furthermore, phylogenetic analysis and comparison of promoter sequences suggest that thogotoviruses can be divided into groups that do or do not regulate intersegment promoter activity via the base pair at positions 5'12 and 3'11. HighlightsO_LIMinigenome systems of Oz virus and Dhori virus reveal segment-specific differences in promoter activity C_LIO_LIThe distal duplex sequence modulates RNA synthesis in a virus-dependent manner C_LIO_LIThe base pair at positions 5'12/3'11 determines promoter activity in Oz virus but not in Dhori virus C_LIO_LIThogotoviruses can be divided into groups that do or do not regulate promoter activity via distal duplex sequence variation at positions 5'12/3'11 C_LI

microbiology↗

bioRxiv2025

Cellular and molecular fine mapping pinpoints new immunopathology of lupus

Systemic lupus erythematosus (SLE) is a complex autoimmune disease with an unknown etiology. To pinpoint new disease-relevant cell states and their molecular profiles, we performed an in-depth investigation of multimodal single-cell datasets comprising [~]2.1 million peripheral blood mononuclear cells from 346 donors. By resolving 123 fine-grained cell states across 27 cell types, we identified previously uncharacterized populations distinctively associated with clinical severity and treatment status, including GZMK+GZMH+HLA-DR+ effector memory CD8+ T cells (double-positive [DP] EMCD8) and FOXO1+ARHGAP15+ T cells. Through extensive statistical frameworks and multimodal approaches, we delineated their aberrant immune signaling networks, transcriptional regulators, key surface proteins, T cell receptor repertoires, and genetic/epigenetic landscapes, underscoring them as candidate drivers of SLE immunopathology. These findings provide new insights into therapeutic target discovery in SLE.

immunology↗

bioRxiv2025

Recovery of infectious Oz virus from cloned cDNA

Oz virus (OZV) is a tick-borne, six-segmented, negative-strand RNA virus in the genus Thogotovirus, family Orthomyxoviridae. A fatal human infection was reported in Japan in 2023. In this study, we established a reverse genetics system to generate infectious recombinant OZV. Six plasmids encoding the full-length OZV genome segments under a murine RNA polymerase I promoter, together with four plasmids expressing viral proteins essential for polymerase activity, were co-transfected into murine cells. This approach enabled efficient recovery of infectious OZV. The recovered recombinant virus exhibited replication kinetics comparable to wild-type OZV. This system provides a platform for molecular studies of OZV.

microbiology↗

bioRxiv2025

Simulating human foot mechanics during walking based on an anatomically detailed forward dynamic finite element model

PurposeForward dynamic musculoskeletal simulation is a powerful computational approach for investigating the biomechanics of human locomotion. However, existing models often oversimplify foot anatomy, thereby limiting our understanding of the role of detailed foot morphology in gait mechanics. In this study, we developed an anatomically accurate three-dimensional finite element (FE) model of the human foot to simulate its dynamic behavior during the stance phase of walking using an explicit forward dynamics approach. MethodsThe model incorporated detailed representations of bones, soft tissues, ligaments, and the plantar aponeurosis, and was driven by experimentally measured tibial kinematics and estimated muscle forces. ResultsSimulation results reasonably matched experimental data on ground reaction forces, plantar pressure distributions, and bone movements, confirming the models ability to replicate key aspects of foot-ground interactions during walking. Moreover, the model enabled the estimation of internal forces, stresses, and strains in foot structures that are not directly measurable in vivo, offering new insights into the biomechanics underlying foot pathologies. ConclusionsThis study potentially provides a robust framework for exploring the form-function relationship of the human foot, with applications in evolutionary biology, clinical interventions, and the study of locomotor disorders.

bioengineering↗

bioRxiv2025

Urinary exfoliated cells exhibit mesodermal lineage differentiation potential in the absence of dedicated culture conditions

IntroductionUrine contains various cells derived from the kidney, including renal tubular epithelial cells, glomerular epithelial cells, and mesenchymal stem cells. Urinary exfoliated mesenchymal stem cells can be differentiated into adipocytes, osteoblasts, chondrocytes, muscle cells, or neuronal cells, if grown in specialized culture conditions. In this study, however, we identified the development of multiple mesodermal cell lineages from urinary exfoliated cells despite using a single culture system not designed for these cell differentiations. MethodsUrinary exfoliated cells used for culturing were obtained from pediatric patients with kidney disease. All cultures were maintained using an identical, non-specifically supplemented, rich, DMEM/F12-based growth medium, refreshed regularly throughout the experiments. Cells of different mesodermal lineages--adipocytes, osteoblasts, and chondrocytes--were identified by staining with Oil Red O, Alizarin Red, and Alcian Blue solutions. Moreover, the expression of mRNA markers specific for adipocytes, osteoblasts, and chondrocytes, as well as for stem cells and--more specifically--mesenchymal stem cells, was analyzed by RT-PCR. ResultsAlthough the abundances varied, in all 11 cultures of urinary exfoliated cells from six patients, dye staining revealed multiple cell clusters of mesodermal lineages. All cultures contained clusters of the adipocyte and chondrocyte lineages, and seven also contained clusters of the osteoblast lineage. Morphology differences were found even between clusters stained with the same dye. RT-PCR confirmed the presence of the three lineages, while also revealing expression of genes specific to pluripotent stem cells (Nanog, Oct3/4, SOX2, and LIF) and genes more specific for mesenchymal stem cells (CD73, CD90, and CD105). ConclusionsAmong urinary exfoliated cells cultured using our method, clusters of cells of mesodermal lineages were observed without needing to selectively adjust the culture medium. The cells seemed to differentiate and proliferate from mesenchymal stem cells in the urine. We envision that these initial findings may eventually contribute to a deeper understanding of urinary stem cell differentiation and to optimizing lineage-specific differentiation for research and therapeutic applications.

cell biology↗

bioRxiv2025

A transcriptomic approach to understand genetic networks of regeneration, cell plasticity, and longevity of the Immortal Jellyfish Turritopsis dohrnii (Cnidaria, Hydrozoa)

When medusae of Turritopsis dohrnii are damaged, wounded, or exposed to otherwise lethal conditions, they revert to an earlier life cycle stage (the polyp) through an intermediate and transient benthic stage, the cyst, thus effectively escaping death. By employing a super transcriptome approach, we profile how the expression putative homologs of genes involved in regeneration, pluripotency, and longevity, change throughout life cycle stages of T. dorhnii. We follow the expression of putative homologs of Sirtuins, factors that control telomere maintenance, heat shock proteins (HSPs), and the Yamanaka transcription factor families (POU, Sox, Klf, Myc). We show that during its life cycle reversal, T. dohrnii manipulates genetic networks of high relevance in biomedical studies in mammals, such as SIRT3, POU factors, RTEL1, and HSP70/90. Our data showcase T. dohrnii as an in vivo research system that can contribute to understanding the genetic networks that regulate cell programming and ontogeny reversal.

genomics↗

bioRxiv2025

Calcineurin-responsive zinc finger 1 (Crz1) contributes to stress tolerance and virulence in the pathogenic fungus Trichosporon asahii

The pathogenic fungus Trichosporon asahii causes severe invasive fungal infections in immunocompromised patients with neutropenia. In Cryptococcus neoformans, calcineurin-responsive zinc finger 1 (Crz1) functions as a transcription factor downstream of the calcineurin signaling pathway and regulates the expression of genes involved in stress resistance and virulence. In T. asahii, Cna1 and Cnb1, which are key components of the calcineurin pathway, contribute to various stress responses and virulence. The role of Crz1 in stress tolerance and virulence in T. asahii, however, has remained unclear. Here we demonstrate that a crz1 gene-deficient T. asahii mutant exhibited increased sensitivity to cell wall and endoplasmic reticulum stress. The crz1 gene-deficient mutant was sensitive to Congo red and tunicamycin, but not to dithiothreitol or sodium dodecyl sulfate. Moreover, the virulence of the crz1 gene-deficient mutant in the silkworm infection model was reduced. These phenotypes of the crz1 gene-deficient mutant were restored by reintroducing the crz1 gene, confirming the association between Crz1 and these phenotypes. The half maximal lethal dose of the cnb1 gene-deficient T. asahii mutant was higher than that of the crz1 gene-deficient mutant. These results suggest that Crz1 plays a role in mediating the stress responses and virulence of T. asahii. The involvement of Crz1 in the virulence of T. asahii is small, however, compared to that of the calcineurin.

microbiology↗

bioRxiv2025

Role of Atg1 in morphologic changes of the pathogenic fungus Trichosporon asahii

Trichosporon asahii is a dimorphic fungus that causes severe invasive fungal infections, particularly in patients with neutropenia. Depending on nutrient availability, T. asahii exists in yeast, hyphae, or arthroconidia forms. Autophagy, a cellular degradation pathway that removes old or damaged organelles, is essential for the survival of many eukaryotic organisms under nutrient-limited conditions. Atg1 is a key regulator of the early phases of autophagy, especially under nitrogen starvation. The role of Atg1 in regulating morphology, stress resistance, or virulence in T. asahii, however, remains poorly understood. Here, we generated three atg1 gene-deficient T. asahii mutants and investigated their phenotypic characteristics to reveal the role of Atg1 in T. asahii. The atg1 gene-deficient mutants exhibited no growth defects under high-temperature or various chemical stress conditions, including antifungal drugs. The mutants exhibited an increased proportion of hyphal cells when cultured in Sabouraud dextrose broth (SB), a medium commonly used for fungi. On the other hand, no morphologic differences were observed between the parent strain and the atg1 gene-deficient mutants under a nitrogen-limited condition. The virulence of these atg1 gene-deficient mutants was maintained in a silkworm infection model. Furthermore, all three generated atg1 gene-deficient mutants exhibited consistent phenotypes. Our findings suggest that while Atg1 does not play a major role in stress tolerance or virulence in T. asahii, it plays a role in regulating its dimorphic morphologic changes.

microbiology↗

bioRxiv2025

Non-DNA-damaging DNA-PK activation improving hearing and prolonging life due to NAD+ and SIRT upregulation

Emerging evidence strongly supports a close relationship between age-related hearing loss and frailty, highlighting the importance of early detection and intervention. Recently, we invented a mitochondria-homing drug named mitochonic acid 5 (MA-5), that increases the adenosine triphosphate (ATP) levels, rescue mitochondrial function, and protect tissue damages. Currently, the phase I clinical trial has been finished in Japan (jRCT2031210495) and the phase 2 clinical trial has already been approved by PMDA. Here we show that MA-5 improved various types of hearing loss in mouse models. Structural chemical bioanalysis revealed that MA-5 is a mixture of equal amount of S- and R- enantiomer and both S- and R- enantiomer increase ATP by binding mitochondrial protein, mitofilin. However, S-enantiomer significantly increased the NAD+ levels by binding to the NAD+-producing key enzyme nicotinamide phosphoribosyltransferase (NAMPT). Moreover, the S-enantiomer increased the sirtuin 1 protein by suppressing polyubiquitination induced by tripartite motif containing 28 (TRIM28) phosphorylation which was triggered by DNA-dependent protein kinase (DNA-PK) activation in the absence of DNA damage. Transcriptomic signatures showed that the signature of MA-5 shows an inverse correlation with aging and mortality and is oriented in the same direction as the OSKM-related iPSCs, suggesting the modification of aging pathways. Oral administration of MA-5 to mitochondrial disease model mouse showed increased survival. Our findings suggest that, in addition to enhancing ATP levels, the coordinated regulation of NAD+ metabolism, SIRT protein expression, and DNA-PK activity-constituting a novel therapeutic triad may contribute to the amelioration of hearing impairment and mitochondrial dysfunction, thereby improving life prognosis.

cell biology↗

bioRxiv2025

Nanopore sequencing-based measurement of paramyxovirus RNA editing reveals virus-specific differences in editing efficiency of mRNA, antigenome and genome

Paramyxovirus polymerase recognizes an RNA editing signal on the viral genome and transcribes mRNA in which guanine nucleotides are inserted in a template-independent manner. This enables the synthesis of multiple proteins from a single gene, which is important for viral growth. We developed a method to quantify RNA editing efficiency using Oxford Nanopore Technologies MinION platform. We performed sequence analysis of reverse transcription (RT)-PCR amplicons with the RNA editing sites in cells infected with Sendai virus (SeV) and canine distemper virus (CDV). By modifying RT primers, we simultaneously assessed RNA editing efficiency in mRNA, antigenome and genome. We observed distinct differences in mRNA editing efficiency between SeV and CDV. Notably, while RNA editing in SeV is confined to mRNA, in CDV it is also observed in antigenome/genome. (Anti)genomes harboring extra nucleotides may deviate from a multiple-of-six sequence, suggesting that RNAs not following the "Rule of Six" are produced in CDV-infected cells. HighlightsO_LIA method was established to quantify RNA editing efficiency in RNAs from paramyxovirus-infected cells using the MinION platform. C_LIO_LIRNA editing efficiency in mRNA differs between Sendai virus and canine distemper virus. C_LIO_LIAlthough RNA editing is confined to mRNA during Sendai virus infection, it is also observed in the antigenome and genome during canine distemper virus infection. C_LI

microbiology↗

bioRxiv2025

Functional analysis of promoter element 2 within the viral polymerase gene of an emerging paramyxovirus, Sosuga virus

Paramyxovirus genomes carry bipartite promoters at the 3 ends of both their genome and antigenome, thereby initiating RNA synthesis, which requires the viral polymerase to recognize two elements: the primary promoter element 1 (PE1) and the secondary promoter element 2 (PE2). We have previously shown that the antigenomic PE2 (agPE2) in many viruses in the Rubulavirinae subfamily is located within the coding region of the viral RNA polymerase L gene. Sosuga virus (SOSV), belonging to the Rubulavirinae subfamily, is highly pathogenic to humans, thus necessitating high-level containment facilities for infectious virus research. The use of a minigenome system permits studies of viral RNA synthesis at lower biosafety levels. Because minigenomes of negative-strand RNA viruses generally comprise only the untranslated regions, agPE2 within the L coding region--such as those found in Rubulavirinae like SOSV--are typically omitted. However, generating an SOSV minigenome that retains agPE2 led to a pronounced increase in activity, enabling a detailed examination of the role of agPE2 in SOSV replication. In many Rubulavirinae, the agPE2 not only acts as a promoter but also encodes part of the L protein, resulting in a distinct motif at the C-terminus of the L protein. We have further shown that this motif is preserved even in Rubulavirinae that no longer contain the agPE2 within the L gene. ImportanceParamyxoviruses are classified into three major subfamilies: Orthoparamyxovirinae, Avulavirinae and Rubulavirinae. All paramyxovirus genomes and antigenomes possess bipartite promoters, comprising two elements: promoter element 1 (PE1) at the 3 end and promoter element 2 (PE2) located internally. We previously revealed that, in many Rubulavirinae, the antigenomic PE2 lies within the coding region of the viral RNA polymerase L gene. In this study, we used Sosuga virus, a member of the Rubulavirinae subfamily, to elucidate the role of antigenomic PE2 in viral replication. Because the PE2 region encodes part of the L protein, its presence leads to a distinctive motif at the C-terminus of L protein. Notably, this motif is conserved in all Rubulavirinae, including those that do not harbor the antigenomic PE2 within their L gene, indicating its importance in viral propagation.

microbiology↗

bioRxiv2024

Widespread genetic testing control inherited polycystic kidney disease in cats

A genetic variant of PKD1 in cats, which causes polycystic kidney disease (PKD), is a target for direct-to-consumer genetic testing to assess PKD risk; however, its effect on genetic structure in cat populations remains unexplored. Therefore, in this study, we aimed to examine the changes in feline PKD and the PKD1 variant across breeds and over time using a large dataset of 110,325 insured and 61,968 genetic-tested cats from 14 breeds. Results revealed that the PKD1 variant frequency significantly decreased, with a reduction of 42.6% before 2019 and after 2022. Systematic genomic analysis revealed no differences in genetic structure or inbreeding levels. The effective population size of cats with the PKD1 variant decreased between points. Overall, these findings highlight the potential of direct-to-consumer genetic testing in promoting more optimized breeding practices and enhancing feline welfare.

genetics↗

bioRxiv2024

A deletion at the X-linked ARHGAP36 gene locus is associated with the orange coloration of tortoiseshell and calico cats

The X-linked orange (O) locus in domestic cats controls an unknown molecular mechanism that causes the suppression of black-brownish pigmentation in favor of orange coloration. The alternating black-brownish and orange patches seen in tortoiseshell and calico cats are considered as classic examples of the phenotypic expression of random X-chromosome inactivation (XCI) occurring in female mammals. However, the O gene in the cat genome has not been identified, and the genetic variation responsible for the orange coloration remains unknown. We report here that a 5.1-kilobase (kb) deletion within an intron of the X-linked ARHGAP36 gene, encoding a Rho GTPase activating protein, is closely and exclusively associated with orange coloration. The deleted region contains a highly conserved putative regulatory element, whose removal presumably cause altered ARHGAP36 expression. Notably, ARHGAP36 expression in cat skin tissues is linked to the suppression of many melanogenesis genes, potentially shifting pigment synthesis from eumelanin to pheomelanin. Furthermore, we find evidence that the gene undergoes XCI in female human and mouse cells, and XCI-dependent CpG island methylation consistent with random XCI in female domestic cats. The 5.1-kb deletion seems widespread in domestic cats with orange coat coloration, suggesting a single origin of this coat color phenotype.

genetics↗

bioRxiv2024

Segment-specific promoter activity for RNA synthesis in the genome of Oz virus, genus Thogotovirus

Oz virus (OZV), a tick-borne, six-segmented negative-strand RNA virus in the genus Thogotovirus, caused a fatal human infection in Japan in 2023. To investigate mechanisms of viral RNA synthesis, we developed an OZV minigenome assay used in mammalian cells. Comparisons of promoter activities across six segments revealed that Segment 5 exhibited markedly lower promoter activity. Unlike the other segments forming a "distal duplex", a double-strand RNA beginning at the 11th nucleotide on the 5 end and the 10th on the 3, Segment 5 partially lacks this feature. Introducing a mutation in Segment 5 distal duplex resulted in a substantial increase in promoter activity. Further, we examined the promoter structures of other viruses in the genus Thogotovirus using public database. Thogoto virus Segment 1 also partially lacks a base pair in the distal duplex. In six-segmented RNA viruses, promoter activities are varied, with notable differences in activities likely existing among segments. HighlightsO_LIA minigenome assay was developed to elucidate the RNA synthesis mechanism of Oz virus. C_LIO_LISegment 5 of the Oz virus exhibits significantly lower promoter activity compared to other segments. C_LIO_LIThe distal duplex region formed by double-strand RNA at the genomic ends is essential for Oz virus RNA synthesis. C_LIO_LIPromoter activities in six-segmented RNA viruses are inherently variable among segments. C_LI

microbiology↗