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Morita T.,Fisheries Research Agency | Niwa K.,Fisheries Research Agency | Fujimoto K.,Fisheries Research Agency | Kasai H.,Fisheries Research Agency | And 15 more authors.
Science of the Total Environment | Year: 2010

Iodine-131 (physical half-life: 8.04days) was detected in brown algae collected off the Japanese coast. Brown algae have been extensively used as bioindicators for radioiodine because of their ability to accumulate radionuclides in high concentration factors. The maximum measured specific activity of 131I in brown algae was 0.37±0.010Bq/kg-wet. Cesium-137 was also detected in all brown algal samples used in this study. There was no correlation between specific activities of 131I and 137Cs in these seaweeds. The specific activity of 137Cs ranged from 0.0034±0.00075 to 0.090±0.014Bq/kg-wet. Low specific activity and minimal variability of 137Cs in brown algae indicated that past nuclear weapon tests were the source of 137Cs. Although nuclear power stations and nuclear fuel reprocessing plants are known to be pollution sources of 131I, there was no relationship between the sites where 131I was detected and the locations of nuclear power facilities. Most of the sites where 131I was detected were near big cities with large populations. Iodine-131 is frequently used in diagnostic and therapeutic nuclear medicine. On the basis of the results, we suggest that the likely pollution source of 131I, detected in brown seaweeds, is not nuclear power facilities, but nuclear medicine procedures. © 2010 Elsevier B.V.


Nagashima Y.,Tokyo University of Marine Science and Technology | Matsumoto T.,Tokyo University of Marine Science and Technology | Kadoyama K.,Tokyo University of Marine Science and Technology | Ishizaki S.,Tokyo University of Marine Science and Technology | Terayama M.,Miyazaki Prefectural Fisheries Experimental Station
Journal of Toxicology | Year: 2011

Green toadfish Lagocephalus lunaris inhabits tropical and subtropical seas and contains high tetrodotoxin (TTX) levels in the muscle as well as liver and gonad. In 2008 to 2009, food poisoning due to ingesting L. lunais occurred in Western Japan. Five specimens of green toadfish caught in Kyushu coast, Japan, were analyzed for toxicity, toxins, and species identification. All five specimens were toxic by bioassay. Comparing the maximum toxicity in tissues, ovary contained the most toxin (1810 mouse unit [MU]/g), followed by liver (341MU/g), muscle (135MU/g), skin (79MU/g), and intestine (72MU/g). Liquid chromatography/mass spectrometry analysis revealed that TTX was the major toxin. Nucleotide sequence analysis of the 16S rRNA gene fragment of muscle mitochondrial DNA indicated that partial sequences of PCR products of four specimens were identical with that of L. lunaris. The sequence of one specimen was indistinguishable from that of the brown-backed toadfish Lagocephalus wheeleri, a nontoxic species. Copyright © 2011 Yuji Nagashima et al.


Nishiki I.,University of Miyazaki | Furukawa M.,Miyazaki Prefectural Fisheries Experimental Station | Matui S.,University of Miyazaki | Itami T.,University of Miyazaki | And 2 more authors.
Fisheries Science | Year: 2011

In Japan, Lactococcus garvieae infection has been the main fish disease in aquaculture. Although commercial oral and injectable vaccines have been used to prevent L. garvieae infection in Japan, L. garvieae has been isolated not only from unvaccinated fish but also from vaccinated fish in which immunity induced by vaccination had diminished. In order to obtain epidemiological information on this fish pathogen, we conducted biased sinusoidal field gel electrophoresis (BSFGE) pattern analysis and phage typing of L. garvieae isolates (n = 427) from fish in Japan. These isolates were obtained from 13 different fish species between 1980 and 2007. In the BSFGE analysis, L. garvieae isolates were classified into 17 groups (S1-S17) based on the SmaI digestion patterns and into four groups (A1-A4) based on the ApaI digestion patterns. Phage typing revealed five different phage susceptibility profiles (A-E) in L. garvieae isolates. Since 2005, comparisons of the results of phage typing and BSFGE have indicated the presence of a novel genotype (S16/A4) with phage type E. All the strains belonging to this type showed lincomycin sensitivity. © 2011 The Japanese Society of Fisheries Science.


Ismail T.F.,University of Miyazaki | Ismail T.F.,Cairo University | Nakamura A.,Miyazaki Prefectural Fisheries Experimental Station | Nakanishi K.,Miyazaki Prefectural Fisheries Experimental Station | And 5 more authors.
Fisheries Science | Year: 2012

Resazurin microtiter assay (REMA) was carried out using four sulfonamides, three culture media, and four inoculum sizes as a first screening step to establish an easy-to-interpret sulfonamides susceptibility testing method for Nocardia seriolae. The in vitro activity of sulfamonomethoxine (SMM) against 190 clinical N. seriolae isolates was then examined, and in vivo experimental treatment was performed. When the culture medium and the inoculum size were considered in tandem, a 0. 5× the original concentration of cation-adjusted Mueller-Hinton broth and an inoculum size of 10 2 CFU/well showed the clearest endpoint reading for all tested drugs, and the REMA-generated data were in excellent agreement with those generated by the reference Etest method. SMM activity showed minimum inhibitory concentration (MIC) values of 4-32 μg/ml against all tested N. seriolae isolates. Treatment of amberjack groups experimentally infected with N. seriolae isolates having SMM MICs of 4 and 32 μg/ml, resulted in survival rates of 100% and 87. 5% in the two groups, respectively. In this study, we developed a simple visual method to test SMM activity against N. seriolae. © 2012 The Japanese Society of Fisheries Science.


Nagashima Y.,Tokyo University of Marine Science and Technology | Matsumoto T.,Tokyo University of Marine Science and Technology | Kadoyama K.,Tokyo University of Marine Science and Technology | Ishizaki S.,Tokyo University of Marine Science and Technology | And 4 more authors.
Journal of the Food Hygienic Society of Japan | Year: 2012

Food poisoning due to ingestion of a puffer fish occurred in Nagasaki Prefecture, Japan, in October 2008, causing neurotoxic symptoms similar to those of tetrodotoxin (TTX) poisoning. In the present study, we identified the species, toxicity, and toxins using the remaining samples of the causative puffer fish. The puffer fish was identified as smooth-backed blowfish Lagocephalus inermis by nucleotide sequence analysis of the 16S rRNA and cytochrome b gene fragments of muscle mitochondrial DNA. The residual liver sample showed toxicity as high as 1,230 mouse unit (MU)/g by bioassay and TTX was detected by liquid chromatography/mass spectrometry analysis. We therefore concluded that the food poisoning was due to TTX caused by consumption of the toxic liver of L. inermis. This is the first report that the liver of L. inermis caught in Japanese waters is strongly toxic, with levels exceeding 1,000 MU/g. In this context, we re-examined the toxicity of L. inermis collected off the coast of Japan. Of 13 specimens assayed, 12 were toxic, although the toxicity varied markedly among individuals and tissues. Because the intestine and ovary of L. inermis have been considered non-toxic, it is particularly noteworthy that these organs were determined to be toxic, with a maximum toxicity of 43.6 MU/g and 10.0 MU/g, respectively. Furthermore, kidney, gallbladder, and spleen, whose toxicity has been unknown, were frequently found to be weakly toxic with levels ranging from 10 to 99 MU/g. Therefore, further study is needed to re-examine the toxicity of smooth-backed blowfish L. inermis in the coastal waters of Japan.


Nishiki I.,University of Miyazaki | Minami T.,Miyazaki Prefectural Fisheries Experimental Station | Itami T.,University of Miyazaki | Yoshida T.,University of Miyazaki
Journal of Fish Diseases | Year: 2014

Lancefield group C Streptococcus dysgalactiae (GCSD) causes severe necrotic lesions in the caudal peduncle in the genus Seriola farmed in Japan. To develop a sero-diagnostic method for GCSD infection in farmed fish, we attempted to identify a surface immunogenic protein that induces an antibody after infection with GCSD by immunoblot analysis using sera collected from infected fish. A protein obtained from sodium dodecyl sulfate (SDS) extracts of GCSD was identified as S. dysgalactiae surface immunogenic protein (Sd-Sip). Sd-Sip exhibited more than 94% homology with a surface antigen or a hypothetical protein from S. dysgalactiae mammalian isolates at the nucleotide sequence level. Expression of the recombinant Sd-Sip (rSd-Sip) was confirmed by immunoblot analysis, that is, its reactivity to GCSD-infected sera. Antibody detection ELISA using rSd-Sip and their usefulness for diagnosis of GCSD infection were examined. GCSD-infected sera collected from farmed amberjack, Seriola dumerili (Risso), showed strong reaction with immobilized rSd-Sip. Meanwhile, sera immunized by other pathogenic bacteria of fish were showed ELISA values similar to those of non-infected sera. These results of this study suggest that the antibody detection ELISA using rSd-Sip is an effective diagnostic method for GCSD infection in fish. © 2013 John Wiley & Sons Ltd.


Nishiki I.,University of Miyazaki | Minami T.,Miyazaki Prefectural Fisheries Experimental Station | Itami T.,University of Miyazaki | Yoshida T.,University of Miyazaki
Fish Pathology | Year: 2014

To develop a rapid diagnosis method for Lancefield group C Streptococcus dysgalactiae (GCSD) infection, latex beads were coated with recombinant S. dysgalactiae surface immunogenic protein (rSd-Sip). The usefulness of the beads for slide agglutination tests with fish sera was examined. The beads were agglutinated with GCSD-infected sera collected from farmed amberjack Seriola dumerili. However, the beads were not agglutinated with non-infected sera or immunized sera collected from fish vaccinated with Lactococcus garvieae and Streptococcus iniae. The results demonstrate that the slide agglutination test using rSd-Sip-coated latex beads is an easy, rapid, and effective method for agglutinating antibody-detection in GCSD-infected fish. © 2014 The Japanese Society of Fish Pathology.

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