Publications by authors named "Yasuhiro Gotoh"

Four bacterial strains with yellow-colored colonies, which were isolated from the radioactive element-containing water in Fukushima Daiichi nuclear power station unit 2, were identified as . Here, we present the complete genome sequences of these species assembled via a combination of short-read and long-read sequencing techniques.

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Yersinia pseudotuberculosis (Ypt) is a gram-negative bacterium that infects both humans and animals primarily through fecal‒oral transmission. While Ypt causes acute gastroenteritis in humans, an association with Kawasaki disease (KD), a disease that primarily affects infants and young children and causes multisystemic vasculitis, has also been suspected. Although KD represents a significant health concern worldwide, the highest annual incidence rate is reported in Japan.

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Giant viruses are crucial for marine ecosystem dynamics because they regulate microeukaryotic community structure, accelerate carbon and nutrient cycles, and drive the evolution of their hosts through co-evolutionary processes. Previously reported long-term observations revealed that these viruses display seasonal fluctuations in abundance. However, the underlying genetic mechanisms driving such dynamics of these viruses remain largely unknown.

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Unlabelled: We investigated the impact of intracellular hydrogen sulfide (HS) hyperaccumulation on the transcriptome of . The wild-type (WT) strain overexpressing , encoding 3-mercaptopyruvate sulfur transferase, produced significantly higher HS levels than the control WT strain. The -overexpressing strain exhibited increased resistance to antibiotics, supporting the prior hypothesis that intracellular HS contributes to oxidative stress responses and antibiotic resistance.

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  • Shiga toxin-producing E. coli (STEC) causes severe gastrointestinal issues, particularly linked to Stx2, which poses greater risks than Stx1.
  • A study of 71 strains in the O145:H28 lineage reveals the dynamic nature of Stx phages, including their acquisition, transfer, and variations affecting Stx2 production levels.
  • Short-tailed Stx2 phages are associated with higher production levels of Stx2 than long-tailed variants, highlighting genetic differences that influence these levels.
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  • - Community-associated methicillin-resistant Staphylococcus aureus (CA-MRSA) infections are rising as a public health concern, particularly in community settings like maternity clinics, with a specific outbreak in Japan identified through analysis techniques.
  • - A study analyzed 151 CA-MRSA isolates, identifying 133 related to the outbreak, which belonged to a lineage called the TDC clone, part of the clonal complex 30 (SWP clone).
  • - The research highlighted that the TDC clone had been present before the outbreak, showing long persistence in carriers, high transmission within households, and significant genetic changes tied to mobile genetic elements that affected antibiotic resistance.
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In gram-negative bacteria, IS26 often exists in multidrug resistance (MDR) regions, forming a pseudocompound transposon (PCTn) that can be tandemly amplified. It also generates a circular intermediate called the "translocatable unit (TU)", but the TU has been detected only by PCR. Here, we demonstrate that in a Klebsiella pneumoniae MDR clone, mono- and multimeric forms of the TU were generated from the PCTn in a preexisting MDR plasmid where the inserted form of the TU was also tandemly amplified.

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While conjugation-related genes have been identified in many plasmids by genome sequencing, functional analyses have not yet been performed in most cases, and a full set of conjugation genes has been identified for only a few plasmids. Rts1, a prototype IncT plasmid, is a conjugative plasmid that was originally isolated from Proteus vulgaris. Here, we conducted a systematic deletion analysis of Rts1 to fully understand its conjugation system.

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  • Microbiota composed of fungi and bacteria significantly influences the physiological functions of larvae, though the specific species and their impacts are not well understood.
  • The study found that a specific yeast is crucial for larval growth in the early fermentation stages, while a particular bacterium takes over as the primary growth supporter in later stages, needing the coexistence of yeasts and lactic acid bacteria for stability.
  • The microbiota enhances larval nutrition and promotes gene activity related to cell growth and metabolism, highlighting the important role of these microbial species during developmental transitions.
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The complete genome sequences of 11 Japanese isolates were determined by hybrid assembly of long and short reads, including two strains isolated from patients with acute infectious purpura fulminans, six strains from patients with sepsis, and three strains from patients with pneumonia.

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  • Plasmids contribute significantly to the genetic diversity of bacteria, as evidenced by the study analyzing 142 closed genomes, which identified 132 plasmids in various strains, highlighting their role in genome evolution.
  • The research found that while there was no significant difference in plasmid numbers between clinical and non-clinical strains, certain hospital-adapted lineages (like clade 2) contained more plasmids, with a notable proportion being associated with antimicrobial and heavy metal resistance.
  • Clustering analysis revealed distinct groups of plasmids with varied GC content and highlighted their potential for interclade transmission and wider host-range capabilities, suggesting a complex ecological relationship among strains in different environments. *
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  • The study investigates ixodid ticks associated with bat families in Eurasia, revealing significant genetic differences among tick species across different regions, particularly in Eastern Asia.
  • By conducting detailed morphological comparisons and analyzing molecular and phylogenetic relationships, the researchers identified and described three new tick species previously thought to be variations of existing ones.
  • The findings indicate that these new species exhibit high genetic divergence, particularly in the cytochrome oxidase subunit (coxI) gene, which supports their classification as separate species based on both genetic and morphological lines.
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Escherichia fergusonii strains have been isolated from patients with diarrhea, but their virulence determinant has not been well elucidated. Here, we report the first isolation of a heat-labile enterotoxin 1 (LT1)-producing E. fergusonii strain (strain 30038) from a patient in Japan.

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  • - The study focuses on cryptic clade I (C-I) within the Escherichia genus, suggesting it's a subspecies of E. coli that is challenging to differentiate from the classic E. coli, leaving its population structure and virulence unclear.
  • - Researchers analyzed 804 isolates, identifying 465 true C-I strains, including a harmful strain linked to a patient with bloody diarrhea, finding a significant presence of virulence and antibiotic resistance genes in these strains.
  • - The results indicate that C-I strains could be emerging human pathogens, mainly sourced from bovines, highlighting the need for more extensive surveillance and studies to understand C-I strains and their impact on health better.
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  • Pathogenic strains in swine lead to significant economic losses, particularly in Japan where antimicrobial use is higher compared to other farm animals.
  • A recent study analyzed 1,708 strains from diseased swine over nearly three decades (1991-2019) and identified increasing multidrug-resistant strains, including resistant serogroups O116 and OSB9.
  • The study found that although third-generation cephalosporins had a low resistance rate, alternative antimicrobials like apramycin and bicozamycin were more effective against highly multidrug-resistant strains.
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  • "Candidatus Rickettsia kotlanii" is a newly identified tick-borne pathogen associated with spotted fever, first found in Hungary in 2006.
  • Researchers sequenced the complete genomes of two Japanese isolates to clarify its evolutionary relationship within the spotted fever group of Rickettsia, revealing that it forms an independent branch within this category.
  • Despite having nearly identical genomes, the isolates came from different tick species and locations, indicating low genetic diversity, while some genes present in "Ca. R. kotlanii" were found to be degraded, necessitating further study on its unique features.
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  • Shiga toxin (Stx), produced by Stx-producing E. coli (STEC), is crucial for the bacteria's virulence and is encoded by bacteriophages known as Stx phages.
  • A study focusing on the O26:H11 STEC lineage (specifically ST21) revealed significant genetic diversity among Stx1a phages, indicating various evolutionary changes, including the replacement of phages.
  • Additionally, the research showed notable differences in Stx1 toxin production linked to variations in Stx1 phages and host factors, emphasizing the complexity of phage-host interactions in toxin production.
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  • The study focuses on Shiga toxin-producing E. coli (STEC), particularly on the O165:H25 strain and its relationship to closely related strains, defining them all as clonal complex 119 (CC119).
  • Researchers conducted whole-genome sequencing of 202 strains to analyze their genetic similarities and differences, focusing on the presence and behavior of specific phages and virulence genes.
  • The findings revealed that the CC119 lineage retains certain genetic traits that enhance virulence, but also shows notable variations in toxin production and lacks genes typical for tellurite resistance, indicating potential vulnerabilities in these strains.
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  • * The study involved genome sequencing of 510 strains, including 147 from Japan, and analyzed variations in Stx2 production levels, which are associated with disease severity.
  • * Results showed distinct genetic diversity in Stx2a phages among the lineages, particularly that SG8_30 strains produced more Stx2 and caused more severe illnesses compared to SG8_32 strains.
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  • Subspecies serovar Oranienburg (SO) is typically a foodborne pathogen that rarely leads to serious infections like bacteremia; however, in 2018, 12 cases were reported in healthy individuals in southern Kyushu, Japan.
  • A study using Randomly Amplified Polymorphic DNA (RAPD) analysis and whole-genome sequencing (WGS) aimed to explore the genetic similarities of the bacteremia strains and other SO isolates, revealing the bacteremia strains formed a distinct cluster.
  • Findings indicate that the 12 cases resulted from a single SO clone, which may have a propensity for causing bacteremia, highlighting the need for increased surveillance on this clone and its relatives in future studies.
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Objective: Elizabethkingia anophelis causes meningitis, bloodstream infections, and respiratory infections in immunocompromised individuals. We examined two E. anophelis strains isolated from the first life-threatening cases caused by this species in Japan to determine the phylogenetic origin and genomic features of them.

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Non-healing claw lesions (NHCLs) are a newly characterized disorder affecting the deep dermis of the hoof in dairy cattle. Although NHCLs are thought to be associated with bovine digital dermatitis (BDD), their precise etiology is not yet understood. To investigate the bacterial populations present in each type of NHCL (toe necrosis: TN, non-healing white line disease: nhWLD, and a non-healing sole ulcer: nhSU), and the newly added entity non-healing verrucous-like lesions (nhVLL), 16S rRNA-based metagenomic analysis with next-generation sequencing (NGS) was employed.

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  • Glutamine synthetase (GS) is crucial for nitrogen assimilation when nitrogen is limited, but the regulation of related metabolic pathways remains unclear.
  • The expression of SucA, a component of 2-oxoglutarate dehydrogenase, is repressed under nitrogen scarcity through post-transcriptional mechanisms involving the Hfq-dependent sRNA GlnZ, which binds to the GS mRNA.
  • This study highlights the complex interaction between mRNA, GlnZ, and transcriptional regulators like Nac to maintain balance in metabolite supply and demand during nitrogen metabolism.
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