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Hajime Uchida
Fisheries Technology Institute, Japan Fisheries Research and Education Agency, 2-12-4 Fukuura, Kanazawa, Yokohama, Kanagawa, 236-8648, Japan

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Journal article
Published: 22 June 2021 in Toxicon
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Lipophilic marine biotoxins azaspiracids (AZAs) are produced by dinoflagellates Azadinium and Amphidoma. Recently, several strains of Azadinium poporum were isolated from Japanese coastal waters. In our present study, AZA analogues in two strains (mdd421 and HM536) of A. poporum were analyzed by several detection techniques on the liquid chromatography-tandem mass spectrometry (LC-MS/MS) and liquid chromatography-quadrupole time of flight mass spectrometry (LC-QTOFMS). The dominant AZA analogue in the Japanese A. poporum strains was AZA2. Other known AZA analogues were AZA11, AZA35, AZA2 methyl ester and AZA2 phosphate ester. Besides these AZAs, thirteen new AZA analogues were discovered in the two strains. A putative AZA analogue (Compound 1) with the smallest molecular weight ever found in nature was also discovered in the two strains. This is the first report describing detailed AZA profiles in Japanese isolates of A. poporum.

ACS Style

Mayu Ozawa; Hajime Uchida; Ryuichi Watanabe; Ryoji Matsushima; Hiroshi Oikawa; Kazuya Takahashi; Mitsunori Iwataki; Toshiyuki Suzuki. Complex profiles of azaspiracid analogues in two culture strains of Azadinium poporum (Amphidomataceae, Dinophyceae) isolated from Japanese coastal waters determined by LC-MS/MS. Toxicon 2021, 199, 145 -155.

AMA Style

Mayu Ozawa, Hajime Uchida, Ryuichi Watanabe, Ryoji Matsushima, Hiroshi Oikawa, Kazuya Takahashi, Mitsunori Iwataki, Toshiyuki Suzuki. Complex profiles of azaspiracid analogues in two culture strains of Azadinium poporum (Amphidomataceae, Dinophyceae) isolated from Japanese coastal waters determined by LC-MS/MS. Toxicon. 2021; 199 ():145-155.

Chicago/Turabian Style

Mayu Ozawa; Hajime Uchida; Ryuichi Watanabe; Ryoji Matsushima; Hiroshi Oikawa; Kazuya Takahashi; Mitsunori Iwataki; Toshiyuki Suzuki. 2021. "Complex profiles of azaspiracid analogues in two culture strains of Azadinium poporum (Amphidomataceae, Dinophyceae) isolated from Japanese coastal waters determined by LC-MS/MS." Toxicon 199, no. : 145-155.

Journal article
Published: 01 March 2021 in Harmful Algae
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Diarrhetic shellfish poisoning (DSP) is caused by the consumption of shellfish contaminated by diarrhetic shellfish toxins (DSTs) such as okadaic acid (OA) and dinophysistoxins (DTXs) produced by some species of dinoflagellates. To prevent the occurrence of human intoxication cases, inspection of DSTs (OA and DTXs) in shellfish is important. An instrumental method using liquid chromatography-tandem mass spectrometry (LC/MS/MS) has been recently employed in Japan for the monitoring of OA and DTXs in shellfish. For such analysis, reference materials (RMs) of OA and DTXs are essential. Demand for the reference materials, especially dinophysistoxin-1 (DTX1), is recently increasing in Japan. Production of the materials has been performed by mass cultivation of a dinoflagellate (Prorocentrum lima) strain that produces DTXs and OA, which indicates that the efficiency of production depends on the toxin production of the strain used. In this study, P. lima complex subclade 1e strain MIO12P was determined to be a high DTX1 producer among the three Japanese strains of the P. lima complex (subclades 1e, 1f, and 1i). It was clarified that the culture medium suitable for toxin production by strain MIO12P was metals mix SWII medium, and the optimal temperature and salinity for toxin production were 25 °C and salinity 30, respectively. The DTX1 yield (1265.3 ng ml−1) of strain MIO12P cultured under the conditions described above was the highest reported worldwide. Prorocentrum lima complex subclade 1e strain MIO12P is expected to be useful for the sustainable production of DTX1 as a source of RMs for chemical and biochemical methods in the future.

ACS Style

Kana Hashimoto; Hajime Uchida; Tomohiro Nishimura; Hiroshi Oikawa; Hiroshi Funaki; Chiho Honma; Haruo Yamaguchi; Toshiyuki Suzuki; Masao Adachi. Determination of optimal culture conditions for toxin production by a Prorocentrum lima complex strain with high diarrhetic shellfish toxins yield. Harmful Algae 2021, 103, 102025 .

AMA Style

Kana Hashimoto, Hajime Uchida, Tomohiro Nishimura, Hiroshi Oikawa, Hiroshi Funaki, Chiho Honma, Haruo Yamaguchi, Toshiyuki Suzuki, Masao Adachi. Determination of optimal culture conditions for toxin production by a Prorocentrum lima complex strain with high diarrhetic shellfish toxins yield. Harmful Algae. 2021; 103 ():102025.

Chicago/Turabian Style

Kana Hashimoto; Hajime Uchida; Tomohiro Nishimura; Hiroshi Oikawa; Hiroshi Funaki; Chiho Honma; Haruo Yamaguchi; Toshiyuki Suzuki; Masao Adachi. 2021. "Determination of optimal culture conditions for toxin production by a Prorocentrum lima complex strain with high diarrhetic shellfish toxins yield." Harmful Algae 103, no. : 102025.

Communication
Published: 23 February 2021 in Symmetry
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A novel symmetrical macrocyclic phthalate hexaester (1) and a known macrocyclic phthalate tetraester (2) were isolated during a natural product-exploring program on the cyanobacterium Moorea producens. Their structures were elucidated based on spectroscopic data, including nuclear magnetic resonance and high-resolution mass spectra. In the antibacterial activity test, compounds 1 and 2 showed no bioactivity at the concentrations tested.

ACS Style

Michiya Kamio; Weina Jiang; Hiroki Osada; Masayuki Fukuoka; Hajime Uchida; Ryuichi Watanabe; Toshiyuki Suzuki; Hiroshi Nagai. Isolation and Structure Elucidation of a Novel Symmetrical Macrocyclic Phthalate Hexaester. Symmetry 2021, 13, 361 .

AMA Style

Michiya Kamio, Weina Jiang, Hiroki Osada, Masayuki Fukuoka, Hajime Uchida, Ryuichi Watanabe, Toshiyuki Suzuki, Hiroshi Nagai. Isolation and Structure Elucidation of a Novel Symmetrical Macrocyclic Phthalate Hexaester. Symmetry. 2021; 13 (2):361.

Chicago/Turabian Style

Michiya Kamio; Weina Jiang; Hiroki Osada; Masayuki Fukuoka; Hajime Uchida; Ryuichi Watanabe; Toshiyuki Suzuki; Hiroshi Nagai. 2021. "Isolation and Structure Elucidation of a Novel Symmetrical Macrocyclic Phthalate Hexaester." Symmetry 13, no. 2: 361.

Journal article
Published: 13 November 2020 in Harmful Algae
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Macroalgal samples were collected from coastal waters in subboreal to subtropical zones in Japan (< 3–30 m depths) and 32 clonal strains of non-motile dinoflagellate-like protists were established. Molecular phylogenetic analyses of the LSU rDNA D1/D2, SSU rDNA, ITS region, and concatenated SSU rDNA + LSU rDNA D1/D2 sequences revealed that the strains nested within the genus Alexandrium. They were separated into three novel phylotypes: Alexandrium spp. type 1, type 2, and type 3. Analysis of the concatenated sequences revealed that the most closely related species for the three phylotypes was A. ostenfeldii. Most cells from strains of the three phylotypes were non-motile and hemispherical to spherical in shape. The average diameters of the non-motile cells were between 35 and 39 µm. Type 1 and type 2 were widely distributed in Japan from the temperate to subtropical zones, whereas type 3 was restricted to the temperate zone. Furthermore, type 2 was widespread from shallow to deep waters, whereas type 1 and type 3 were restricted to deep waters. Growth experiments in strains belonging to the three phylotypes revealed that the occurrence ratios of motile cells were very low (≤ 1.1% of the total cells). The production of paralytic shellfish poisoning toxins, tetrodotoxin, and cyclic imines was assessed in strains belonging to the three phylotypes by LC/MS/MS analysis. The strains did not produce any of the toxins tested. The strains of the three phylotypes showed lethal toxicity to mice by intraperitoneal administration. To the best of our knowledge, this is the first study to report the existence of Alexandrium associated with marine macroalgae from Japan.

ACS Style

Tomohiro Nishimura; Yuki Kuribara; Ryo Fukuzawa; Katsuya Mimura; Hiroshi Funaki; Kouki Tanaka; Ryuichi Watanabe; Hajime Uchida; Toshiyuki Suzuki; Masao Adachi. First report of Alexandrium (Dinophyceae) associated with marine macroalgae off Japan: Diversity, distribution, and toxicity. Harmful Algae 2020, 104, 101924 .

AMA Style

Tomohiro Nishimura, Yuki Kuribara, Ryo Fukuzawa, Katsuya Mimura, Hiroshi Funaki, Kouki Tanaka, Ryuichi Watanabe, Hajime Uchida, Toshiyuki Suzuki, Masao Adachi. First report of Alexandrium (Dinophyceae) associated with marine macroalgae off Japan: Diversity, distribution, and toxicity. Harmful Algae. 2020; 104 ():101924.

Chicago/Turabian Style

Tomohiro Nishimura; Yuki Kuribara; Ryo Fukuzawa; Katsuya Mimura; Hiroshi Funaki; Kouki Tanaka; Ryuichi Watanabe; Hajime Uchida; Toshiyuki Suzuki; Masao Adachi. 2020. "First report of Alexandrium (Dinophyceae) associated with marine macroalgae off Japan: Diversity, distribution, and toxicity." Harmful Algae 104, no. : 101924.

Journal article
Published: 20 August 2020 in Separation and Purification Technology
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Selenoneine is an organic selenium compound found in blood of tuna. Selenoneine has two conformational structures: the reduced monomer, and the oxidized dimer formed through a Se-Se bond. Presence of the two forms depends on the environmental chemical properties and oxidative conditions. The selenoneine dimer has been isolated from a genetically modified fission yeast following fermentation but the selenoneine monomer has not been reported because it co-elutes with ergothioneine due to their chemical similarity between selenium and thiol functional groups. In this study, we investigated the separation of selenoneine monomer and ergothioneine in aqueous solutions by high-performance liquid chromatography using a pentabromobenzyl column characterized by London dispersion force interactions. Selenoneine monomer and ergothioneine were completely separated, with a peak resolution (Rs) of 4.16. The obtained selenoneine had a purity of 88.4% as a selenium compound and the recovery efficiency was 52.8%. This is the first method reported for the separation of selenoneine monomer.

ACS Style

Takuya Seko; Hajime Uchida; Yumiko Yamashita; Michiaki Yamashita. Novel method for separating selenoneine reduced monomer and ergothioneine from fission yeast extracts. Separation and Purification Technology 2020, 254, 117607 .

AMA Style

Takuya Seko, Hajime Uchida, Yumiko Yamashita, Michiaki Yamashita. Novel method for separating selenoneine reduced monomer and ergothioneine from fission yeast extracts. Separation and Purification Technology. 2020; 254 ():117607.

Chicago/Turabian Style

Takuya Seko; Hajime Uchida; Yumiko Yamashita; Michiaki Yamashita. 2020. "Novel method for separating selenoneine reduced monomer and ergothioneine from fission yeast extracts." Separation and Purification Technology 254, no. : 117607.

Communication
Published: 22 January 2020 in Molecules
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A new aplysiatoxin derivative, neo-aplysiatoxin A (1), along with seven known compounds, neo-debromoaplysiatoxin A (2), dolastatin 3 (3), lyngbic acid (4), malyngamide M (5), hermitamide A (6), (−)-loliolide (7), and (+)-epiloliolide (8), was isolated from the Okinawan cyanobacterium Moorea producens. Their structures were elucidated on the basis of spectroscopic data, including high-resolution mass spectrometry and nuclear magnetic resonance. The compounds were evaluated for cytotoxic and diatom growth inhibition activities.

ACS Style

Mioko Kawaguchi; Masayuki Satake; Bo-Tao Zhang; Yue-Yun Xiao; Masayuki Fukuoka; Hajime Uchida; Hiroshi Nagai. Neo-Aplysiatoxin A Isolated from Okinawan Cyanobacterium Moorea Producens. Molecules 2020, 25, 457 .

AMA Style

Mioko Kawaguchi, Masayuki Satake, Bo-Tao Zhang, Yue-Yun Xiao, Masayuki Fukuoka, Hajime Uchida, Hiroshi Nagai. Neo-Aplysiatoxin A Isolated from Okinawan Cyanobacterium Moorea Producens. Molecules. 2020; 25 (3):457.

Chicago/Turabian Style

Mioko Kawaguchi; Masayuki Satake; Bo-Tao Zhang; Yue-Yun Xiao; Masayuki Fukuoka; Hajime Uchida; Hiroshi Nagai. 2020. "Neo-Aplysiatoxin A Isolated from Okinawan Cyanobacterium Moorea Producens." Molecules 25, no. 3: 457.

Journal article
Published: 25 November 2019 in Harmful Algae
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In the present study, the abundance of Prorocentrum and the molecular phylogeny, distribution, and DST production of P. lima complex and P. caipirignum in Japan were investigated. First, the cell densities of Prorocentrum were assessed from the temperate to subtropical zones in Japan between 2014 and 2018. The cell density in the subtropical zone [19.0 ± 40.2 cells/g wet weight (ww) algae] was significantly higher than that in the temperate zone (1.4 ± 3.4 cells/g ww algae). A total of 244 clonal strains were established from the temperate and subtropical zones. Phylogenetic analyses based on the large-subunit ribosomal DNA D1/D2 revealed that the strains were separated into four species/species complex/phylotypes (P. limacomplex, P. caipirignum, and new phylotypes Prorocentrum spp. types 1 and 2). The strains of P. lima complex could be separated into two clades (1 and 3). Furthermore, the strains of clades 1 and 3 could be separated into nine subclades (1a, 1c, 1d, 1e, 1f, 1 g, 1 h, 1i, and 1 j) and three subclades (3a, 3b, and 3c), respectively. The strains of P. caipirignum were separated into two subclades (b and e). Each phylotype/subclade showed a unique distribution pattern in Japan: P. lima complex subclades 1a, 1c, and 3a and P. caipirignum subclades b and e were widespread from the temperate to subtropical zones. On the other hand, P. lima complex subclades 1e and 1i were restricted to the temperate zone, and P. lima complex subclades 1d, 1f, 1 g, 1 h, 1 j, 3b, and 3c and Prorocentrum spp. types 1 and 2 were restricted to the subtropical zone. Furthermore, the DST production of the 243 clonal strains was assessed by LC/MS/MS analysis. The results revealed that all strains produced okadaic acid (OA) and that the OA contents of P. lima complex subclades 1d and 1f, P. caipirignum subclades b and e, and Prorocentrum sp. type 2 tended to be higher than those of the other subclades. While P. lima complex subclades 1a, 1e, 1f, and 1i produced DTX1, the other phylotype/subclades produced either no or low quantities of DTX1. A strain of P. lima complex subclade 1e showed the highest OA and DTX1 contents (55.27 and 70.73 pg/cell, respectively) in the world. These results suggest that there are potential risks for DST accumulation in benthic animals in Japan.

ACS Style

Tomohiro Nishimura; Hajime Uchida; Ryoko Noguchi; Hiroshi Oikawa; Toshiyuki Suzuki; Hiroshi Funaki; Chiho Ihara; Kyoko Hagino; Shingo Arimitsu; Yuta Tanii; Shota Abe; Kana Hashimoto; Katsuya Mimura; Kouki Tanaka; Ippei Yanagida; Masao Adachi. Abundance of the benthic dinoflagellate Prorocentrum and the diversity, distribution, and diarrhetic shellfish toxin production of Prorocentrum lima complex and P. caipirignum in Japan. Harmful Algae 2019, 96, 101687 .

AMA Style

Tomohiro Nishimura, Hajime Uchida, Ryoko Noguchi, Hiroshi Oikawa, Toshiyuki Suzuki, Hiroshi Funaki, Chiho Ihara, Kyoko Hagino, Shingo Arimitsu, Yuta Tanii, Shota Abe, Kana Hashimoto, Katsuya Mimura, Kouki Tanaka, Ippei Yanagida, Masao Adachi. Abundance of the benthic dinoflagellate Prorocentrum and the diversity, distribution, and diarrhetic shellfish toxin production of Prorocentrum lima complex and P. caipirignum in Japan. Harmful Algae. 2019; 96 ():101687.

Chicago/Turabian Style

Tomohiro Nishimura; Hajime Uchida; Ryoko Noguchi; Hiroshi Oikawa; Toshiyuki Suzuki; Hiroshi Funaki; Chiho Ihara; Kyoko Hagino; Shingo Arimitsu; Yuta Tanii; Shota Abe; Kana Hashimoto; Katsuya Mimura; Kouki Tanaka; Ippei Yanagida; Masao Adachi. 2019. "Abundance of the benthic dinoflagellate Prorocentrum and the diversity, distribution, and diarrhetic shellfish toxin production of Prorocentrum lima complex and P. caipirignum in Japan." Harmful Algae 96, no. : 101687.

Journal article
Published: 01 October 2019 in Toxins
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Saxitoxin (STX) and its analogues produced by toxic dinoflagellates accumulate in bivalves, and routine monitoring of bivalves is important to prevent cases of human poisoning. In this study, we describe a rapid detection method for the analysis of STXs using ultra-performance liquid chromatography with post-column fluorescent detection and to investigate water depths and sampling points optimal for shellfish toxin monitoring. Cultured scallops (Mizuhopecten yessoensis) and mussels (Mytilus galloprovincialis) collected from various water depths and sampling points were used in this study. Irrespective of bivalve species, toxin concentrations in bivalves were lower at deeper water depths. The toxin concentrations of bivalves did not differ greatly when bivalves were collected from the same bay. Although the levels of contamination of bivalves with STXs can depend on various environmental and geographical factors, our findings are useful for formulating a sampling protocol for the prevention of harvesting contaminated shellfish.

ACS Style

Ryuichi Watanabe; Makoto Kanamori; Hidetsugu Yoshida; Yutaka Okumura; Hajime Uchida; Ryoji Matsushima; Hiroshi Oikawa; Toshiyuki Suzuki. Development of Ultra-Performance Liquid Chromatography with Post-Column Fluorescent Derivatization for the Rapid Detection of Saxitoxin Analogues and Analysis of Bivalve Monitoring Samples. Toxins 2019, 11, 573 .

AMA Style

Ryuichi Watanabe, Makoto Kanamori, Hidetsugu Yoshida, Yutaka Okumura, Hajime Uchida, Ryoji Matsushima, Hiroshi Oikawa, Toshiyuki Suzuki. Development of Ultra-Performance Liquid Chromatography with Post-Column Fluorescent Derivatization for the Rapid Detection of Saxitoxin Analogues and Analysis of Bivalve Monitoring Samples. Toxins. 2019; 11 (10):573.

Chicago/Turabian Style

Ryuichi Watanabe; Makoto Kanamori; Hidetsugu Yoshida; Yutaka Okumura; Hajime Uchida; Ryoji Matsushima; Hiroshi Oikawa; Toshiyuki Suzuki. 2019. "Development of Ultra-Performance Liquid Chromatography with Post-Column Fluorescent Derivatization for the Rapid Detection of Saxitoxin Analogues and Analysis of Bivalve Monitoring Samples." Toxins 11, no. 10: 573.

Communication
Published: 21 June 2019 in Toxins
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Cyanobacteria have been shown to produce a number of bioactive compounds, including toxins. Some bioactive compounds obtained from a marine cyanobacterium Moorea producens (formerly Lyngbya majuscula) have been recognized as drug leads; one of these compounds is aplysiatoxin. We have isolated various aplysiatoxin derivatives from a M. producens sample obtained from the Okinawan coastal area. The frozen sample was extracted with organic solvents. The ethyl acetate layer was obtained from the crude extracts via liquid-liquid partitioning, then separated by HPLC using a reversed-phase column. Finally, 1.1 mg of the compound was isolated. The chemical structure of the isolated compound was elucidated with spectroscopic methods, using HR-MS and 1D and 2D NMR techniques, and was revealed to be oscillatoxin I, a new member of the aplysiatoxin family. Oscillatoxin I showed cytotoxicity against the L1210 mouse lymphoma cell line and diatom growth-inhibition activity against the marine diatom Nitzschia amabilis.

ACS Style

Hiroshi Nagai; Shingo Sato; Kaori Iida; Kazutaka Hayashi; Mioko Kawaguchi; Hajime Uchida; Masayuki Satake. Oscillatoxin I: A New Aplysiatoxin Derivative, from a Marine Cyanobacterium. Toxins 2019, 11, 366 .

AMA Style

Hiroshi Nagai, Shingo Sato, Kaori Iida, Kazutaka Hayashi, Mioko Kawaguchi, Hajime Uchida, Masayuki Satake. Oscillatoxin I: A New Aplysiatoxin Derivative, from a Marine Cyanobacterium. Toxins. 2019; 11 (6):366.

Chicago/Turabian Style

Hiroshi Nagai; Shingo Sato; Kaori Iida; Kazutaka Hayashi; Mioko Kawaguchi; Hajime Uchida; Masayuki Satake. 2019. "Oscillatoxin I: A New Aplysiatoxin Derivative, from a Marine Cyanobacterium." Toxins 11, no. 6: 366.

Journal article
Published: 06 November 2018 in Toxins
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The identification and quantification of okadaic acid (OA)/dinophysistoxin (DTX) analogues and pectenotoxins (PTXs) in Dinophysis samples collected from coastal locations around Japan were evaluated by liquid chromatography mass spectrometry. The species identified and analyzed included Dinophysis fortii, D. acuminata, D. mitra (Phalacroma mitra), D. norvegica, D. infundibulus, D. tripos, D. caudata, D. rotundata (Phalacroma rotundatum), and D. rudgei. The dominant toxin found in D. acuminata was PTX2 although some samples contained DTX1 as a minor toxin. D. acuminata specimens isolated from the southwestern regions (Takada and Hiroshima) showed characteristic toxin profiles, with only OA detected in samples collected from Takada. In contrast, both OA and DTX1, in addition to a larger proportion of PTX2, were detected in D. acuminata from Hiroshima. D. fortii showed a toxin profile dominated by PTX2 although this species had higher levels of DTX1 than D. acuminata. OA was detected as a minor toxin in some D. fortii samples collected from Yakumo, Noheji, and Hakata. PTX2 was also the dominant toxin found among other Dinophysis species analyzed, such as D. norvegica, D. tripos, and D. caudata, although some pooled picked cells of these species contained trace levels of OA or DTX1. The results obtained in this study re-confirm that cellular toxin content and profiles are different even among strains of the same species.

ACS Style

Hajime Uchida; Ryuichi Watanabe; Ryoji Matsushima; Hiroshi Oikawa; Satoshi Nagai; Takashi Kamiyama; Katsuhisa Baba; Akira Miyazono; Yuki Kosaka; Shinnosuke Kaga; Yukihiko Matsuyama; Toshiyuki Suzuki. Toxin Profiles of Okadaic Acid Analogues and Other Lipophilic Toxins in Dinophysis from Japanese Coastal Waters. Toxins 2018, 10, 457 .

AMA Style

Hajime Uchida, Ryuichi Watanabe, Ryoji Matsushima, Hiroshi Oikawa, Satoshi Nagai, Takashi Kamiyama, Katsuhisa Baba, Akira Miyazono, Yuki Kosaka, Shinnosuke Kaga, Yukihiko Matsuyama, Toshiyuki Suzuki. Toxin Profiles of Okadaic Acid Analogues and Other Lipophilic Toxins in Dinophysis from Japanese Coastal Waters. Toxins. 2018; 10 (11):457.

Chicago/Turabian Style

Hajime Uchida; Ryuichi Watanabe; Ryoji Matsushima; Hiroshi Oikawa; Satoshi Nagai; Takashi Kamiyama; Katsuhisa Baba; Akira Miyazono; Yuki Kosaka; Shinnosuke Kaga; Yukihiko Matsuyama; Toshiyuki Suzuki. 2018. "Toxin Profiles of Okadaic Acid Analogues and Other Lipophilic Toxins in Dinophysis from Japanese Coastal Waters." Toxins 10, no. 11: 457.

Journal article
Published: 20 October 2018 in Toxins
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Ciguatera fish poisoning (CFP) is a type of food poisoning caused by the consumption of a variety of toxic ciguatera fish species in the tropical and subtropical waters. Although there have been a large number of suspected CFP cases in the Southeast Asian countries, few were confirmed with causative ciguatoxins (CTXs), and reliable information on the symptoms still remains rather limited. In the present study, CTXs in red snapper Lutjanus bohar, implicated in two suspected CFP cases in Vietnam in 2014 and 2016, were determined by use of the single-quadrupole selected ion monitoring (SIM) liquid chromatography/mass spectrometry (LC/MS). Ciguatoxin-1B (CTX-1B), 54-deoxyCTX-1B, and 52-epi-54-deoxyCTX-1B were detected in the red snapper by our LC/MS method. Moreover, CTX-1B, 54-deoxyCTX-1B, and 52-epi-54-deoxyCTX-1B were further identified by the time of flight (TOF) LC/MS with the exact mass spectrum. The CTX profile of the red snapper in Vietnam is similar to those of ciguatera fish from Australia, Okinawa Islands in Japan, Kiribati, and Hong Kong. This is the first comprehensive report unambiguously identifying the causative toxins in fish implicated with reliable information on the poisoning symptoms in CFP in Vietnam and/or Southeast Asian countries.

ACS Style

Dao Viet Ha; Aya Uesugi; Hajime Uchida; Pham Xuan Ky; Dang Quoc Minh; Ryuichi Watanabe; Ryoji Matsushima; Hiroshi Oikawa; Satoshi Nagai; Mitsunori Iwataki; Yasuwo Fukuyo; Toshiyuki Suzuki. Identification of Causative Ciguatoxins in Red Snappers Lutjanus bohar Implicated in Ciguatera Fish Poisonings in Vietnam. Toxins 2018, 10, 420 .

AMA Style

Dao Viet Ha, Aya Uesugi, Hajime Uchida, Pham Xuan Ky, Dang Quoc Minh, Ryuichi Watanabe, Ryoji Matsushima, Hiroshi Oikawa, Satoshi Nagai, Mitsunori Iwataki, Yasuwo Fukuyo, Toshiyuki Suzuki. Identification of Causative Ciguatoxins in Red Snappers Lutjanus bohar Implicated in Ciguatera Fish Poisonings in Vietnam. Toxins. 2018; 10 (10):420.

Chicago/Turabian Style

Dao Viet Ha; Aya Uesugi; Hajime Uchida; Pham Xuan Ky; Dang Quoc Minh; Ryuichi Watanabe; Ryoji Matsushima; Hiroshi Oikawa; Satoshi Nagai; Mitsunori Iwataki; Yasuwo Fukuyo; Toshiyuki Suzuki. 2018. "Identification of Causative Ciguatoxins in Red Snappers Lutjanus bohar Implicated in Ciguatera Fish Poisonings in Vietnam." Toxins 10, no. 10: 420.

Journal article
Published: 27 September 2018 in Toxins
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Diarrhetic shellfish toxins (DSTs) are a group of phycotoxins that include okadaic acid (OA)/dinophysistoxin (DTX) analogues. At present, detailed data on the distribution of DST is insufficient, and studies of the appropriate sample sizes are lacking. This study investigated the DST frequency distribution in scallops and mussels by liquid chromatography-tandem mass spectrometry (LC/MS/MS) and a resampling analysis of existing data was carried out. The DST population-interval and the necessary sample size were also estimated. DSTs are localized in the scallop digestive-gland, and the DST concentrations in scallops were water-depth-dependent. DST concentrations in scallops and mussels showed normal distributions, but mussels tended to contain more DSTs than scallops. In the statistical resampling analysis of the acquired data on scallops and mussels, especially that using the bootstrap method, sample size was difficult to estimate when the DST variation was large. Although the DST population-interval could be statistically estimated from the sample standard deviation of three samples, the sample size corresponded to the risk management level, and the use of 13 or more samples was preferable. The statistical methods used here to analyze individual contents and estimate population content-intervals could be applied in various situations and for shellfish toxins other than DSTs.

ACS Style

Ryoji Matsushima; Hajime Uchida; Ryuichi Watanabe; Hiroshi Oikawa; Izumi Oogida; Yuki Kosaka; Makoto Kanamori; Tatsuro Akamine; Toshiyuki Suzuki. Anatomical Distribution of Diarrhetic Shellfish Toxins (DSTs) in the Japanese Scallop Patinopecten yessoensis and Individual Variability in Scallops and Mytilus edulis Mussels: Statistical Considerations. Toxins 2018, 10, 395 .

AMA Style

Ryoji Matsushima, Hajime Uchida, Ryuichi Watanabe, Hiroshi Oikawa, Izumi Oogida, Yuki Kosaka, Makoto Kanamori, Tatsuro Akamine, Toshiyuki Suzuki. Anatomical Distribution of Diarrhetic Shellfish Toxins (DSTs) in the Japanese Scallop Patinopecten yessoensis and Individual Variability in Scallops and Mytilus edulis Mussels: Statistical Considerations. Toxins. 2018; 10 (10):395.

Chicago/Turabian Style

Ryoji Matsushima; Hajime Uchida; Ryuichi Watanabe; Hiroshi Oikawa; Izumi Oogida; Yuki Kosaka; Makoto Kanamori; Tatsuro Akamine; Toshiyuki Suzuki. 2018. "Anatomical Distribution of Diarrhetic Shellfish Toxins (DSTs) in the Japanese Scallop Patinopecten yessoensis and Individual Variability in Scallops and Mytilus edulis Mussels: Statistical Considerations." Toxins 10, no. 10: 395.

Communication
Published: 13 October 2016 in Toxins
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ERETIC2 (Electronic Reference To access In vivo Concentrations 2) based on PULCON (Pulse Length–based Concentration determination) methodology is a quantitative NMR (qNMR) using an external standard. The performance of the PULCON method was assessed using maleic acid (MA). Quantification of the diarrhetic shellfish toxin and okadaic acid by PULCON was successfully consistent with that obtained by a conventional internal standard method, demonstrating that the PULCON method is useful for the quantification of invaluable marine toxins without any contaminations by an internal standard.

ACS Style

Ryuichi Watanabe; Chika Sugai; Taichi Yamazaki; Ryoji Matsushima; Hajime Uchida; Masahiro Matsumiya; Akiko Takatsu; Toshiyuki Suzuki. Quantitative Nuclear Magnetic Resonance Spectroscopy Based on PULCON Methodology: Application to Quantification of Invaluable Marine Toxin, Okadaic Acid. Toxins 2016, 8, 294 .

AMA Style

Ryuichi Watanabe, Chika Sugai, Taichi Yamazaki, Ryoji Matsushima, Hajime Uchida, Masahiro Matsumiya, Akiko Takatsu, Toshiyuki Suzuki. Quantitative Nuclear Magnetic Resonance Spectroscopy Based on PULCON Methodology: Application to Quantification of Invaluable Marine Toxin, Okadaic Acid. Toxins. 2016; 8 (10):294.

Chicago/Turabian Style

Ryuichi Watanabe; Chika Sugai; Taichi Yamazaki; Ryoji Matsushima; Hajime Uchida; Masahiro Matsumiya; Akiko Takatsu; Toshiyuki Suzuki. 2016. "Quantitative Nuclear Magnetic Resonance Spectroscopy Based on PULCON Methodology: Application to Quantification of Invaluable Marine Toxin, Okadaic Acid." Toxins 8, no. 10: 294.

Journal article
Published: 07 October 2016 in Harmful Algae
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Toxigenic Dinophysis spp. are obligate mixotrophic dinoflagellates that require a constant supply of prey—Mesodinium rubrum—to achieve long-term growth by means of kleptoplasty. Mesodinium rubrum is, however, a fast moving, jumping ciliate exhibiting an effective escape response from suspensivorous predators. In the present study, a series of laboratory experiments evaluating the motility and survival of M. rubrum in the presence of Dinophysis cells and/or substances contained in their culture medium was designed, in order to assess the mechanisms involved in prey capture by Dinophysis spp. Cell abundance of M. rubrum decreased in the presence of Dinophysis cf. ovum cells producing okadaic acid (OA; up to 7.94 ± 2.67 pg cell−1) and smaller amounts of dinophysistoxin-1 (DTX-1) and pectenotoxin-2 (PTX-2). Prey capture was often observed after the ciliate had been attached to adhesive “mucus traps”, which only appeared in the presence of Dinophysis cells. Before being attached to the mucus traps, M. rubrum cells reduced significantly their swimming frequency (from ∼41 to 19 ± 3 jumps min−1) after only 4 h of initial contact with D. cf. ovum cells. M. rubrum survival was not affected in contact with purified OA, DTX-1 and PTX-2 solutions, but decreased significantly when the ciliate was exposed to cell-free or filtered culture medium from both D. cf. ovum and D. caudata, the latter containing moderate concentrations of free eicosapentaenoic acid and docosahexaenoic acid. The results thus indicate that Dinophysis combines the release of toxic compounds other than shellfish toxins, possibly free PUFAs, and a “mucus trap” to enhance its prey capture success by immobilizing and subsequently arresting M. rubrum cells.

ACS Style

Luiz L. Mafra Jr.; Satoshi Nagai; Hajime Uchida; Camila P.S. Tavares; Bruno P. Escobar; Toshiyuki Suzuki. Harmful effects of Dinophysis to the ciliate Mesodinium rubrum: Implications for prey capture. Harmful Algae 2016, 59, 82 -90.

AMA Style

Luiz L. Mafra Jr., Satoshi Nagai, Hajime Uchida, Camila P.S. Tavares, Bruno P. Escobar, Toshiyuki Suzuki. Harmful effects of Dinophysis to the ciliate Mesodinium rubrum: Implications for prey capture. Harmful Algae. 2016; 59 ():82-90.

Chicago/Turabian Style

Luiz L. Mafra Jr.; Satoshi Nagai; Hajime Uchida; Camila P.S. Tavares; Bruno P. Escobar; Toshiyuki Suzuki. 2016. "Harmful effects of Dinophysis to the ciliate Mesodinium rubrum: Implications for prey capture." Harmful Algae 59, no. : 82-90.

Journal article
Published: 01 December 2015 in Toxins
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Japanese scallops, Patinopecten yessoensis, were fed with the toxic dinoflagellate Dinophysis fortii to elucidate the relative magnitude of assimilation, accumulation, and metabolism of diarrhetic shellfish toxins (DSTs) and pectenotoxins (PTXs). Three individual scallops were separately exposed to cultured D. fortii for four days. The average cell number of D. fortii assimilated by each individual scallop was 7.7 × 105. Dinophysistoxin-1 (DTX1), pectenotoxin-2 (PTX2) and their metabolites were analyzed by liquid chromatography tandem mass spectrometry (LC/MS/MS) and the toxin content in individual tissues (digestive gland, adductor muscle, gill, gonad, mantle, and the others), feces and the seawater medium were quantified. Toxins were almost exclusively accumulated in the digestive gland with only low levels being detected in the gills, mantles, gonads, and adductor muscles. DTX1 and PTX2 were the dominant toxins in the D. fortii cells fed to the scallops, whereas the dominant toxins detected in the digestive gland of scallops were PTX6 and esterified acyl-O-DTX1 (DTX3). In other tissues PTX2 was the dominant toxin observed. The ratio of accumulated to assimilated toxins was 21%–39% and 7%–23% for PTXs and DTXs respectively. Approximately 54%–75% of PTX2 and 52%–70% of DTX1 assimilated by the scallops was directly excreted into the seawater mainly without metabolic transformation.

ACS Style

Ryoji Matsushima; Hajime Uchida; Satoshi Nagai; Ryuichi Watanabe; Michiya Kamio; Hiroshi Nagai; Masaki Kaneniwa; Toshiyuki Suzuki. Assimilation, Accumulation, and Metabolism of Dinophysistoxins (DTXs) and Pectenotoxins (PTXs) in the Several Tissues of Japanese Scallop Patinopecten yessoensis. Toxins 2015, 7, 5141 -5154.

AMA Style

Ryoji Matsushima, Hajime Uchida, Satoshi Nagai, Ryuichi Watanabe, Michiya Kamio, Hiroshi Nagai, Masaki Kaneniwa, Toshiyuki Suzuki. Assimilation, Accumulation, and Metabolism of Dinophysistoxins (DTXs) and Pectenotoxins (PTXs) in the Several Tissues of Japanese Scallop Patinopecten yessoensis. Toxins. 2015; 7 (12):5141-5154.

Chicago/Turabian Style

Ryoji Matsushima; Hajime Uchida; Satoshi Nagai; Ryuichi Watanabe; Michiya Kamio; Hiroshi Nagai; Masaki Kaneniwa; Toshiyuki Suzuki. 2015. "Assimilation, Accumulation, and Metabolism of Dinophysistoxins (DTXs) and Pectenotoxins (PTXs) in the Several Tissues of Japanese Scallop Patinopecten yessoensis." Toxins 7, no. 12: 5141-5154.

Journal article
Published: 18 June 2015 in Marine Drugs
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This study investigates the occurrence of diarrhetic shellfish toxins (DSTs) and their producing phytoplankton species in southern Brazil, as well as the potential for toxin accumulation in co-occurring mussels (Perna perna) and octopuses (Octopus vulgaris). During the spring in 2012 and 2013, cells of Dinophysis acuminata complex were always present, sometimes at relatively high abundances (max. 1143 cells L−1), likely the main source of okadaic acid (OA) in the plankton (max. 34 ng L−1). Dinophysis caudata occurred at lower cell densities in 2013 when the lipophilic toxins pectenotoxin-2 (PTX-2) and PTX-2 seco acid were detected in plankton and mussel samples. Here, we report for the first time the accumulation of DSTs in octopuses, probably linked to the consumption of contaminated bivalves. Perna perna mussels were consistently contaminated with different DSTs (max. 42 µg kg−1), and all octopuses analyzed (n = 5) accumulated OA in different organs/tissues: digestive glands (DGs) > arms > gills > kidneys > stomach + intestine. Additionally, similar concentrations of 7-O-palmytoyl OA and 7-O-palmytoly dinophysistoxin-1 (DTX-1) were frequently detected in the hepatopancreas of P. perna and DGs of O. vulgaris. Therefore, octopuses can be considered a potential vector of DSTs to both humans and top predators such as marine mammals.

ACS Style

Jr. Luiz L. Mafra; Daiana Lopes; Vanessa C. Bonilauri; Hajime Uchida; Toshiyuki Suzuki. Persistent Contamination of Octopuses and Mussels with Lipophilic Shellfish Toxins during Spring Dinophysis Blooms in a Subtropical Estuary. Marine Drugs 2015, 13, 3920 -3935.

AMA Style

Jr. Luiz L. Mafra, Daiana Lopes, Vanessa C. Bonilauri, Hajime Uchida, Toshiyuki Suzuki. Persistent Contamination of Octopuses and Mussels with Lipophilic Shellfish Toxins during Spring Dinophysis Blooms in a Subtropical Estuary. Marine Drugs. 2015; 13 (6):3920-3935.

Chicago/Turabian Style

Jr. Luiz L. Mafra; Daiana Lopes; Vanessa C. Bonilauri; Hajime Uchida; Toshiyuki Suzuki. 2015. "Persistent Contamination of Octopuses and Mussels with Lipophilic Shellfish Toxins during Spring Dinophysis Blooms in a Subtropical Estuary." Marine Drugs 13, no. 6: 3920-3935.