Publications by authors named "Koko Otsuki"

Article Synopsis
  • Mollusc rearing in southeast Brazil has significantly declined, with scallop production dropping from 51.2 tons in 2016 to 10.2 tons in 2022 due to unknown reasons.
  • The study investigated water quality trends and environmental factors impacting the production of scallops, particularly focusing on Nodipecten nodosus over the last decade.
  • Findings indicate that declines in scallop spat production are linked to warmer water temperatures, decreased levels of Chlorophyll a, and increased presence of harmful bacteria, suggesting that global warming and poor seawater quality are key contributors to the industry’s collapse.
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Article Synopsis
  • - The study examines the microbial diversity in sediments from Airo Lake, a floodplain lake in the Amazon, using metagenomics and biogeochemical analysis to understand the impact of the Negro River on the lake's environment.
  • - Three sediment layers were analyzed, revealing distinct microbiomes: older, deeper sediments had a higher abundance of specific bacteria like Burkholderia, while more recent layers contained different microbes like Thermococcus, indicating changes over time.
  • - A significant number of metagenome-assembled genomes (MAGs) identified in the older strata are linked to unknown taxa, suggesting potential new species, and show enrichment in sulfur cycle genes, highlighting the complexity of microbial interactions in this ecosystem.
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The rupture of the Córrego do Feijão dam in Brumadinho (January 25, 2019) caused serious damage to the Paraopeba River and compromised the quality of its waters for human consumption. However, the possible effects of the dam collapse on the river microbiome and its antibiotic resistance profiles are unknown. The present study aims to analyse the possible shifts in microbial diversity and enhancement of antibiotic resistance in the Paraopeba River.

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  • The Great Amazon Reef System (GARS) is a significant marine ecosystem located near the Amazon River, with rhodolith holobionts being key components in the area, which spans 56,000 km.
  • Research aims to determine if environmental conditions like light, temperature, and depth affect the microbiomes of rhodoliths across different sectors (northern, central, southern) of GARS.
  • Findings show that the microbiomes of rhodoliths are mostly similar across the study area but exhibit subtle differences, especially in the southern sector, where higher light leads to increased abundance of certain microbial groups and functional categories linked to photosynthesis and iron metabolism.
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  • A novel Gram-negative, motile bacterial strain (designated A511) was discovered from the skin of pufferfish collected in Brazil, specifically at 20-28 °C with 3% NaCl for optimal growth.
  • The genome of this strain is 4.36 Mb containing 3,976 coding genes and a G+C content of 42.5%.
  • Taxonomic analyses identified A511 as a new species in the Vibrio genus, named Vibrio tetraodonis sp. nov., and revealed gene clusters related to bioactive compounds that may have ecological roles in its pufferfish host.
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  • The study investigates microbial diversity in marine sediments of Guanabara Bay, Brazil, using metagenomics and biogeochemical tools across various sediment depths.
  • Findings reveal that methanogens dominate at shallower depths (1 mbsf), while sulfate-reducing microbes are more prevalent in deeper layers (4 mbsf).
  • A novel microbial order called Guanabacteria was discovered, showcasing distinct genetic traits relevant to sulfur and carbon cycles, highlighting the complex interactions and adaptations of microbial communities in impacted ecosystems.
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Article Synopsis
  • A649 is a novel bacterial species isolated from the healthy pufferfish Sphoeroides spengleri, classified as Enterovibrio baiacu sp nov.
  • Genomic analysis shows A649 has significantly low amino acid/nucleotide identity (less than 95%) and genome similarity (less than 70%) compared to its closest relatives.
  • The complete genome of strain A649 is approximately 5.4 million base pairs long and contains 4,826 coding genes, with unique features for distinguishing it from other Enterovibrio species.
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  • Unplanned oil spills in offshore production pose significant risks to both the industry and marine ecosystems.
  • This research identifies and analyzes the genomes of three new types of bacteria that can break down hydrocarbons: "Colwellia aromaticivorans," "Halocyntiibacter alkanivorans," and "Ulvibacter alkanivorans."
  • Understanding these bacteria could enhance methods for cleaning up oil spills and protecting the marine environment.
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Human T cell lymphotropic virus type 1 (HTLV-1) was the first retrovirus discovered in humans and is endemic in several parts of the world. Because of risk behaviors, mainly sexual, men who have sex with men (MSM) are at high risk of acquiring HTLV-1 infection. A cross-sectional study was performed to estimate the prevalence of HTLV-1 infection, to characterize genetically HTLV-1 sequences and to identify risk behaviors associated with this infection among MSM in Central Brazil.

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One consequence of oil production is the possibility of unplanned accidental oil spills; therefore, it is important to evaluate the potential of indigenous microorganisms (both prokaryotes and eukaryotes) from different oceanic basins to degrade oil. The aim of this study was to characterize the microbial response during the biodegradation process of Brazilian crude oil, both with and without the addition of the dispersant Corexit 9500, using deep-sea water samples from the Amazon equatorial margin basins, Foz do Amazonas and Barreirinhas, in the dark and at low temperatures (4°C). We collected deep-sea samples in the field (about 2570 m below the sea surface), transported the samples back to the laboratory under controlled environmental conditions (5°C in the dark) and subsequently performed two laboratory biodegradation experiments that used metagenomics supported by classical microbiological methods and chemical analysis to elucidate both taxonomic and functional microbial diversity.

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Background: Molecular and epidemiological studies of transmission routes and risk factors for infection by HTLV-1 are extremely important in order to implement control measures, especially because of the high prevalence of HTLV-1 in several regions of the world. San Salvador de Jujuy, Northwest Argentina, is a highly endemic area for HTLV-1 and foci of tropical spastic paraparesis/HTLV-1-associated myelopathy.

Objective: To gain further insight into the role of intrafamilial transmission of HTLV-1 in a highly endemic region in Argentina.

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The taxonomic position of strains Ab112(T) (CBAS 572(T)) and Ab227_MC (CBAS 573) was evaluated by means of genomic taxonomy. These isolates represent the dominant flora cultured from the healthy marine sponge Arenosclera brasiliensis, endemic to Rio de Janeiro. Strains CBAS 572(T) and CBAS 573 shared >98 % 16S rRNA sequence identity with Endozoicomonas numazuensis and Endozoicomonas montiporae.

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Background: Human T-lymphotropic virus type 1 (HTLV-1) has worldwide distribution and is considered endemic in many world regions, including southwestern Japan and Brazil. Japanese immigrants and their descendants have a high risk of acquiring this infection due to intense population exchange between Brazil and Japan.

Objective: This cross-sectional study aimed to estimate the prevalence of HTLV, analyze the main risk factors associated with this infection, identify the main circulating types and subtypes of HTLV in Japanese immigrants and descendants living in Campo Grande-MS (Middle-West Brazil), as well as analyze the phylogenetic relationship among isolates of HTLV.

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Human T-cell lymphotropic virus (HTLV) may impact the clinical course of tuberculosis (TB). Both infections are highly endemic in Brazil. The aim of this study was to assess the prevalence of HTLV-1/2 in TB patients in Central-West Brazil and to perform a genetic characterisation of the respective isolates.

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Human T-lymphotropic virus type 1 (HTLV-1) has a global spread, and it is estimated that around 20 million persons are infected. Seven major genetic subtypes are recognized. However, there are complete genomes only from the HTLV-1a (cosmopolitan) and HTLV-1c (Melanesian) subtypes.

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Background: Human T-Cell Lymphotropic Virus Type 1 (HTLV-1) is the etiological agent of adult T-cell leukemia (ATL) and HTLV-1-associated myelopathy/tropical spastic paraparesis (HAM/TSP). It has been estimated that 10-20 million people are infected worldwide, but no successful treatment is available. Recently, the epidemiology of this virus was addressed in blood donors from Maputo, showing rates from 0.

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The oncoprotein Tax was characterized genetically from a large cohort of human T-cell lymphotropic virus type 1 (HTLV-1) seropositive individuals from the most endemic region of HTLV-1-associated myelopathy/tropical spastic paraparesis (HAM/TSP) and HTLV-1 infection in Argentina, the province of San Salvador de Jujuy. Sixteen HAM/TSP patients and 47 HTLV-1 healthy carriers were evaluated. Six Tax genetic polymorphisms were identified and observed in 70.

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This study aimed to determine the prevalence of HTLV-1 infection among remnant black quilombo communities in Central Brazil. A total of 1,837 individuals were evaluated, among whom nine were HTLV-1/2 seropositive according to ELISA. All of them were positive for HTLV-1 by means of Western blot and/or PCR, thus resulting in a prevalence of 0.

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Background: Here, we investigated the phylogenetic relationships of the HIV-1 subtype F1 circulating in Angola with subtype F1 strains sampled worldwide and reconstructed the evolutionary history of this subtype in Central Africa.

Methods: Forty-six HIV-1-positive samples were collected in Angola in 2006 and subtyped at the env-gp41 region. Partial env-gp120 and pol-RT sequences and near full-length genomes from those env-gp41 subtype F1 samples were further generated.

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Background: Screening for human T-lymphotropic virus-1/2 (HTLV-1/2) infection is not performed in blood banks in Mozambique. The aim was to determine the prevalence of HTLV-1/2 among blood donors of the Maputo Central Hospital Blood Bank and measure the coinfection rate of HTLV-1/2 with human immunodeficiency virus (HIV), hepatitis B virus (HBV), and syphilis.

Study Design And Methods: A total of 2019 consecutive blood donors were screened for HTLV-1/2 antibodies, HIV-1/2 antibodies, hepatitis B surface antigen (HBsAg), and rapid plasma reagin (RPR) for syphilis.

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The province of San Salvador de Jujuy, located in the northwest of Argentina, is a highly endemic area for HTLV-1 infection and a foci of tropical spastic paraparesis/HTLV-1-associated myelopathy (HAM/TSP). Therefore, to better understand this, we carried out a genetic characterization of a large set of HTLV-1 strains (n = 65) of descendants of Amerindians from this region. The LTR and env regions were analyzed.

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