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NO44 - 1 (2009)

The Role of Aquaculture in Upcoming Food Crisis

<>I Chiu Liao*<>Department of Aquaculture, National Taiwan Ocean University,
2 Pei-Ning Road, Keelung, Taiwn

ABSTRACT輸s the global population exceeds 6.5 billion in recent years, aquaculture is destined to play a more important role in providing animal protein in terms of aquaculture potential and high feed conversion rates. Technical and non-technical aspects of aquaculture are discussed in this paper to help sustainable development of this knowledge-based industry, with emphasis on food safety and human welfare. Technical strategies include consolidated standards for each species, introduction of exotic species, improvement of feeds, selective breeding, disease control and others. Non-technical strategies include training of personnel, proper licensing system, implementation of appropriate regulations and laws, efficient monitoring system, and establishment of local and global aquaculture networks.

Key words: aquaculture, sustainable development, limiting factors, technical strategies, non-technical strategies

Control Strategy for Viral Diseases of Salmonid Fish, Flounders and Shrimp at Hatchery and Seed Production Facility in Japan

<>Mamoru Yoshimizu*<>Laboratory of Biotechnology and Microbiology, Faculty of Fisheries Sciences, Hokkaido University
Hakodate, Hokkaido 041-8611, Japan

ABSTRACT祐almonid fish are important species for hatchery reared and released fish. Flounders and shrimp are also important species for seed production and sea-farming in Japan. Viral disease is one of the limitations of successful propagation of these species. Methods currently used to control viral diseases are 1) hygiene and sanitation in facilities, 2) disinfection of rearing and waste water using U. V. irradiation, ozonization and electrolyzation, 3) selection of pathogen-free brood stock by cell culture isolation and detection of specific antibody against important pathogens with ELISA or viral gene with PCR, 4) health monitoring of hatched fry by cell culture isolation and detection of pathogens by immunological and molecular biological methods, 5) control of normal intestinal flora by feeding bacteria producing antiviral substances, and 6) temperature manipulation. Under these circumstances, hatched fish and shrimp are healthy and specific pathogen free, but there is still a possibility of infection by some pathogens in environmental waters after they are moved to ponds or net pens outside of facilities. For prospective studies, development of effective vaccines, vaccine injection machines and immunological tools for evaluation of vaccination effect are necessary.

Key words: salmonid fish, flounder, shrimp, disinfection, UV, ozone, electrolyzation, vaccination

Can Advances in Fish Immunology Change Vaccination Strategies?

<>Christopher J. Secombes*<>Scottish Fish Immunology Research Centre, University of Aberdeen,
Aberdeen AB24 2TZ, Scotland, UK

DNA Vaccines against Viral Diseases: Basic Immunological Aspects and Applied Perspectives

<>Niels Lorenzen*, Ellen Lorenzen, Jesper Skou Rasmussen and Katja Einer-Jensen<>National Veterinary Institute, Technical University of Denmark, Hangoevej 2,
DK-8200 Aarhus N, Denmark

Disease Control in Korean Aquaculture

<>Soo Il Park*<>Department of Aquatic Life Medicine, College of Fisheries Sciences, Pukyong National University, Busan 608-737, Republic of Korea

ABSTRACT輸s the mariculture technique had been developed, annual production of shallow water cultures exceeded that of adjacent water fisheries in recent years in Korea. For reducing production losses from infectious diseases in fish aquaculture, various strategies were employed including treatment of effective chemotherapeutics, development of herbal immunostimulants and vaccination, etc. For the treatment of bacterial diseases, 27 antibacterial agents have been used under government license. Frequent use of these drugs was accompanied with occurrence of drug-resistant bacteria. Recently, new bacterial diseases have occurred in cultured fishes. As the studying on the control activities of medicinal herbs to bacterial growth, the wormwood Artemisia asiatica, the Galla rhois Rhus javanica and the veiled lady mushroom Dictyophora indusiata were revealed high antibacterial activities to the Gram-positive and negative bacteria. For the enhancement of nonspecific immune response in mariculture fish, medicinal herbs and other several materials were investigated as immunostimulants. Olive flounders Paralichthys olivaceus fed on the diet supplemented with 0.1% extract mixture of the wormwood and the barrenwort Epimedium koreanum showed higher relative percent survival (RPS), when they were challenged with bacterial pathogens. To prevent various infectious diseases, two vaccines were developed and commercially available including vaccines on Edwardsiella tarda and Streptococcus iniae.

Key words: immunostimulant, vaccine, herbal medicine, fish pathogen

Presence of Homologous DNAs to M Gene RNA of Infectious Hematopoietic Necrosis Virus in Chum Salmon Oncorhynchus keta

<>Kunio Suzuki1* and D. K. Sakai2<>1Eastern Hokkaido Inland Water Fisheries Section, The Hokkaido Fish Hatchery,
Abashiri, Hokkaido 093-0131, Japan
2Faculty of Bio-industry, Tokyo University of Agriculture,
Abashiri, Hokkaido 099-2493, Japan
(Received March 17, 2008)
ABSTRACT幽omologous DNAs (M DNA) to the infectious hematopoietic necrosis virus (IHNV) M gene were detected in river-homing chum salmon Oncorhynchus keta sperm, eyed-egg embryos, alevins and fry collected from nine rivers and four hatcheries in Hokkaido Prefecture, Japan, in 1998-2002, although no virus titer was observed in the samples. Real-time PCR assay revealed M DNA at the highest number of 1.7 × 104 copies/mg of tissue. Nucleotide sequence similarities between the M DNA and the viral M genes were ≧97%. When CHSE-214 and RTG-2 cells were inoculated with IHNV, the cells contained 3.8 × 101 to 1.8 × 103 copies of M DNA/105 cells and showed cytopathic effects (CPE). Salmonid fish fry and yearlings infected with the virus contained 1.3 ∞ 101 to 2.6 × 103 copies of M DNA/mg of tissue. CHSE-214 cells transfected with the viral RNA produced M DNA without showing CPE. Reverse transcriptase (RTase) activities in the fish cells and the fish tissues were equivalent to 86-578 pg HIV-1 RTase/106 cells and 2.1-12 pg HIV-1 RTase/mg of tissue, respectively. These results suggest that M DNA is produced from IHNV RNA and retained in the fish.

Key words: Infectious hematopoietic necrosis virus, IHNV, M gene, Oncorhynchus keta, real-time PCR, transfection

Serological Differentiation of Streptococcus parauberis Strains Isolated from Cultured Japanese Flounder in Japan

<>Kinya Kanai1*, Miyuki Yamada1, Fei Meng2, Ichirou Takahashi3, Taizo Nagano4,<>Hidemasa Kawakami5, Azumi Yamashita5, Satoru Matsuoka6, Yutaka Fukuda7,
Yasuyuki Miyoshi7, Ikuo Takami8, Heiji Nakano9, Tatsumu Hirae10,
Kimihiro Shutou11 and Toshio Honma11
1Faculty of Fisheries, Nagasaki University, Nagasaki, 852-8521, Japan
2Graduate School of Science and Technology, Nagasaki University,
Nagasaki, 852-8521, Japan
3Hamada Regional Office of Fisheries Affairs, Shimane Prefectural
Government, Hamada, Shimane 697-0041, Japan
4Kagawa Prefectural Fisheries Experimental Station, Takamatsu,
Kagawa 761-0111, Japan
5Ehime Prefectural Fish Disease Control Center, Uwajima, Ehime 798-0087, Japan
6Ehime Prefectural Chuyo Fisheries Experimental Station, Iyo, Ehime
799-3125, Japan
7Fisheries Research Institute, Oita Prefectural Agriculture, Forestry
and Fisheries Research Center, Saiki, Oita 879-2602, Japan
8Nagasaki Prefectural Institute of Fisheries, Nagasaki,
851-2213, Japan
9Kumamoto Prefectural Fisheries Research Institute, Kamiamakusa,
Kumamoto 869-3603, Japan
10Kagoshima Prefectural Fisheries Technology and Development
Center, Ibusuki, Kagoshima 891-0315, Japan
11Bio Science Co., Ltd., Anan, Tokushima
779-1292, Japan

(Received September 1, 2008)

ABSTRACT―Streptococcus parauberis, a Gram-positive bacterium, is known as the causative agent of mastitis in cows as well as streptococcicosis in turbot Scophthalmus maximus and Japanese flounder Paralichthys olivaceus. It has recently become one of the most important pathogens of cultured Japanese flounder in western Japan. In this study, we investigated the serological nature of S. parauberis strains isolated from Japanese flounder in Japan. As a result, the strains were distinctly divided into two groups, serotype I represented by strain KRS-02083 and serotype II represented by strain KRS-02109, by an agglutination test with rabbit antisera. Autoclave-extracts of bacterial cells derived from each serotype formed a type-specific precipitation line with each corresponding antiserum in an agar double diffusion test. Acidic polysaccharides were detected in the autoclave-extracts of the bacterial cells. Electron microscopy revealed capsular structure on the bacterial cells pretreated with each corresponding antiserum. This finding suggests that capsular polysaccharide antigens serve to differentiate two serotypes.

Key words: Streptococcus parauberis, Paralichthys olivaceus, streptococcicosis, serotype, capsule

Characterization of Drug Resistance in Streptococcus parauberis Isolated from Japanese Flounder

Fei Meng1, Kinya Kanai2* and Kazuma Yoshikoshi2
1Graduate School of Science and Technology, Nagasaki University, Nagasaki 852-8521, Japan
2Faculty of Fisheries, Nagasaki University, Nagasaki 852-8521, Japan
(Received October 3, 2008)
ABSTRACT輸ntimicrobial susceptibility of Streptococcus parauberis against nine drugs were investigated in 64 strains isolated from Japanese flounder Paralichthys olivaceus at different culture areas of western Japan, and resistance genes were determined by PCR and Southern blot hybridization. Five of the tested strains belonging to S. parauberis serotype I (44 strains) were resistant to oxytetracycline and erythromycin and were found to possess both tet(S) and erm(B) genes. Minimum inhibitory concentrations (MICs) of oxytetracycline and erythromycin were 128 and 512 μg/mL, respectively. Southern blot hybridization analysis showed that the tet(S) gene was encoded on an 11-kb conjugative plasmid, while the erm(B) gene resided on the chromosomal DNA. All of the examined S. parauberis serotype II strains (20 strains) were tetracycline-resistant (MIC = 32 μg/mL) and were found to possess tet(M) gene. Both int (integrase) and xis (excisase) genes were also detected in all of the serotype II strains, suggesting the presence of Tn916睦elated element in these strains. These results present a threat of difficulty in treatment of S. parauberis infection by tetracyclines, especially those caused by serotype II strains.

Key words: Streptococcus parauberis, Paralichthys olivaceus, Japanese flounder, drug resistance, tet(S), tet(M), erm(B)

The First Isolation of Photobacterium damselae subsp. damselae from Asian Seabass Lates calcarifer

<>Praparsiri Kanchanopas-Barnette1, Alejandro Labella2, Carmen M. Alonso2, Manuel Manchado3, Dolores Castro2 and Juan J. Borrego2*<>1Department of Aquatic Sciences, Faculty of Sciences, Burapha University, Bangsaen,
Chon Buri 20131, Thailand
2Department of Microbiology, Faculty of Sciences,
University of Malaga, Campus Teatinos,
29071-Malaga, Spain
3Centro El Toru, IFAPA, Junta de Andaluc僘,
11500-El Puerto de Santa Mar僘,
C疆iz, Spain

(Received April 4, 2008)

ABSTRACT輸fter transporting Asian seabass Lates calcarifer from a fish farm to the Burapha University facilities, they began to die. The affected or moribund fish exhibited abdominal swelling, yellowish decoloration around the anus, darkening of the gills and exophthalmic eyes. The internal signs of the disease included abdominal cavities filled with a cloudy yellow and gelatinous fluid together with liver hemorrhage. Isolated bacteria from several organs were biochemically characterized as Photobacterium damselae subsp. damselae. It was further confirmed by PCR. An infectivity experiment by intraperitoneal injection with an isolate LCA 24907 showed its virulence to Asian seabass with LD50 of 8.1 × 105 CFU/g fish body weight. This is the first report of isolating P. damselae subsp. damselae from Asian seabass.

Key words: Photobacterium damselae subsp. damselae, Lates calcarifer, Asian seabass