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Nishizawa T.,Chonnam National University | Takami I.,Nagasaki Prefectural Institute of Fisheries | Yoshimizu M.,Hokkaido University | Oh M.-J.,Chonnam National University

It was recently reported that Poly(I:C) immunization of fish confers protection against viral infection. In this process, fish are immunized with a live pathogenic virus followed by administration of Poly(I:C), which induces a transient, non-specific antiviral state. As a result, fish survive the initial immunization with live virus, which would otherwise be lethal. In the present study, we tried to determine the exact dosage of red-spotted grouper nervous necrosis virus (RGNNV), the causative agent of viral nervous necrosis, required for Poly(I:C) immunization of sevenband grouper Epinephelus septemfasciatus. In Poly(I:C) immunization with more than 90% relative percentage survival (RPS) against RGNNV challenge with 104.3 TCID50/fish, approximately 104.0 TCID50/fish or greater of RGNNV was administered by intramuscular (IM) injection, whereas 105.3 TCID50/fish or greater of RGNNV was required for immersion methods. It was concluded that the degree of RGNNV infection must be similar to a fatal dose in order for the fish to become immune to RGNNV. Interestingly, antibody against RGNNV was not detected in the sera of fish immunized by immersion. Thus, Poly(I:C) immunization by immersion may have some interesting effects on the epidermal immune response in fish. © 2010 Elsevier B.V. Source

Kuwahara K.,Nagasaki Prefectural Institute of Fisheries | Konno K.,Hokkaido University
Food Chemistry

The effect of sodium citrate (Na-citrate) on myosin and actin denaturation in myofibrils was investigated. Na-citrate significantly suppressed the thermal inactivation of Ca 2+-ATPase of carp myosin in a concentration-dependent manner. The effect was greater than that of sorbitol. A similar effect was observed with myofibrils in which myosin is stabilized by F-actin binding. Na-citrate dissolved myofibrils at lower concentration than NaCl. Nevertheless, Na-citrate at 1 M failed to denature F-actin in myofibrils, while 1 M NaCl denatured F-actin almost completely. Na-citrate suppressed the NaCl-induced F-actin denaturation. Sorbitol did not show such protective effect on F-actin denaturation. Moreover, Na-citrate suppressed the freeze denaturation of myofibrils at lower concentration than sorbitol. Thus, Na-citrate was proved to be superior to sorbitol. It was suggested that Na-citrate alone could substitute sorbitol as cryoprotectant in surimi and NaCl as dissolving reagent of myofibril in thermal gel production. © 2010. Source

Takami I.,Nagasaki Prefectural Institute of Fisheries | Kwon S.R.,Hokkaido University | Nishizawa T.,Hokkaido University | Nishizawa T.,Chonnam National University | Yoshimizu M.,Hokkaido University
Diseases of Aquatic Organisms

In immunization of fish with polyinosinic-polycytidylic acid (poly[I:C], a synthetic double-stranded RNA), injection of Poly(I:C) followed by challenge with a live virus induces a transient, non-specific antiviral state by interferon activity. When exposed to a virus while in this antiviral state, the fish acquire a specific and protective immunity against the corresponding viral disease and survive. In the present study, the effiacy of Poly(I:C) immunization was investigated in japanese flounder Paralichthys olivaceus using viral hemorrhagic septicemia virus (VHSV) as a model; the minimum dose of Poly(I:C) required for inducing protection and the duration of the antiviral state were determined, and a potentially curative effect of Poly(I:C) administration was assessed. The antiviral state was induced by administration of Poly(I:C) doses ranging from 12.5 to 200 μg fish-1. Minimum dose to induce the antiviral state (relative percentage survival, RPS:90%) was 12.5 μg fish -1. No curative effect of Poly(I:C) was observed in fish pre-infected with VHSV. Fish injected with 200 μg Poly(I:C) fish-1 were highly protected (RPS:100%) from an artificial challenge with VHSV, and specific antibodies against VHSV were detected. The corresponding high level of antiviral state against VHSV was attained 1 d post Poly(I:C) injection, lasted for 6 d and susequently decreased. Moreover, the surviving fish were highly protected from re-challenge with VHSV (RPS:100%). Thus, it was considered that an immunity against viral hemorrhagic septicemia was induced in the Japanese flounder by injecting live VHSV following Poly(I:C) administration. © Inter-Research 2010. Source

Giri A.,Tokyo University of Marine Science and Technology | Osako K.,Tokyo University of Marine Science and Technology | Okamoto A.,Nagasaki Prefectural Institute of Fisheries | Ohshima T.,Tokyo University of Marine Science and Technology
Food Research International

Aroma active compounds in commercial fermented fish meat paste product (fish miso), fermented soy paste (soy miso), fish sauce and soy sauces were characterized by using a dynamic headspace method for volatile isolation and GC olfactometry for odor perception. A total of 123 volatile compounds consisting mainly of aldehydes, alcohols, esters, ketones, furans, sulfur and nitrogen-containing compounds, aromatics and acids were consistently identified. A major 16 odor-active compounds were distinguished to contribute as key aroma compounds for the miso and sauce products. Olfactometric and sensory findings clearly differentiated miso products with caramelic, fruity aroma notes, whereas fish sauce products were characterized by ammoniacal, fishy, nutty and cheesy odor note. Soy sauce products, however, were dominated by nutty and cheese aroma. Use of koji for fish miso production was found effective to enhance sweet aroma to the product with a reduction of nutty, meaty and rancid nuance. Principal component analysis employed for statistical interpretations clearly elucidated the relationship among different types of fermented products. © 2010 Elsevier Ltd. All rights reserved. Source

Matsuoka K.,Nagasaki University | Mizuno A.,Nagasaki University | Iwataki M.,Nagasaki University | Takano Y.,Nagasaki University | And 3 more authors.
Harmful Algae

An unarmored dinoflagellate Cochlodinium polykrikoides has formed red tides responsible for fish mass mortalities especially in coastal areas of western Japan and southern Korea almost every summer to autumn. In laboratory culture, the optimum temperature for growth of the species is ca. 27°C. Since the species cannot survive in water of temperatures of less than 10°C, it was considered to over-winter in some certain regions as a motile form or resting cyst, and expand its distribution after the temperature increases to a level tolerable for growth. To determine the over-wintering regions and migration pattern of C. polykrikoides, occurrences of the motile cells were surveyed in the coastal and offshore areas of western Kyushu, Japan and south coast of the Korean Peninsula from April 2006 to August 2008. Cells of C. polykrikoides were found at 14 sites during the investigated period. Motile cells occurred throughout the year in Usuka Bay, Hirado of West Japan. From offshore regions of the Goto Islands and off Shin-Nagasaki Fishing Port, motile cells of C. polykrikoides were first detected from late May, and continuously occurred until February in Nama Bay of the Kami-Goto Islands. This first appearance was before red tides of C. polykrikoides reported at coastal areas in western Kyushu. In Korea, this species was first observed in May and disappeared after October in 2007. These occurrence patterns imply that Usuka Bay in Hirado is one of the over-wintering regions in western Kyushu, and also this species is possibly transported into the northern part of the East China Sea by the Tsushima Warm Current every year. © 2010 Elsevier B.V. Source

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