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NO43 - 2

Correlation between Chemical Structures and Inhibitory Activities of Anti-bacterial Substances from Marine Pseudoalteromonas sp. A1-J11

<>Carmelo Segovia del Castillo1, Takeshi Yoshikawa2, Masahito Hashimoto3 and Taizo Sakata2*<>1The United Graduate School of Agricultural Sciences, Kagoshima University, Kagoshima 890-0065, Japan
2Laboratory of Microbiology, Faculty of Fisheries, Kagoshima University, Kagoshima 890-0056, Japan
3Department of Nanostructure and Advanced Materials, Graduate School of Science and Engineering, Kagoshima University, Kagoshima 890-0065, Japan
(Received December 13, 2007)
ABSTRACT裕he anti-bacterial substance, AVS-03d, isolated from the culture of marine Pseudoalteromonas sp. A1-J11 was separated by HPLC with a C18 column. The chemical structure of AVS-03d was identified as 2-n-pentyl-4-quinolinol (C14H17NO = 215.13) on the basis of mass spectrometry and NMR spectroscopy. AVS-03d showed strong inhibitory activity against Vibrio harveyi strains as compared with other quinolinol compounds, suggesting that the length of the alkyl side chain of the compound is important for anti-bacterial activity.

Key words: anti-bacterial substance, alkyl-quinolinol, NMR, Pseudoalteromonas

Dysfunction in Respiration and Osmotic Regulation of Larval Japanese Flounder Affected by Viral Epidermal Hyperplasia

<>Yoshisuke Iida1*, Junya Hiroi2, Kenji Namba3 and Toshihiro Nakai3<>1Fisheries & Marine Technology Center, Hiroshima Prefectural Technology Research Institute, Kure, Hiroshima 737-1207, Japan
2Department of Anatomy, St. Marianna University, Kanagawa 216-8511, Japan
3Graduate School of Biosphere Science, Hiroshima University, Higashi-Hiroshima, 739-8528, Japan
(Received December 19, 2007)
ABSTRACT?Flounder herpesvirus (FHV) induces epidermal hyperplasia in larval Japanese flounder Paralichthys olivaceus. We examined the influence of ambient oxygen and salinity concentrations on mortality of flounder larvae by FHV infection. FHV-infected fish showed markedly higher mortality than uninfected fish under normoxia (partial oxygen pressure; PO2 = ca. 160 Torr), but survived at high rates under hyperoxia (PO2 = ca. 280 Torr or higher) as in uninfected fish. In the PO2 range from 100 to 400 Torr, infected fish always displayed lower levels of oxygen consumption (MO2) compared to the uninfected fish. Under PO2 of 260 Torr, the 48 h-survival rate of infected fish in diluted seawater (salinity 8 or 16 ppt) was much higher than that in full-strength seawater (salinity 32 ppt). Whole-mount immunocytochemistry to detect Na+/K+-ATPase and Na+/K+/2Cl- cotransporter of the skin of both infected and uninfected larvae revealed that the infected larvae had a significantly lower number of chloride cells. These results suggest that flounder larvae infected with FHV die of dysfunction in respiration and osmotic regulation.

Key words: flounder herpesvirus, Paralichthys olivaceus, viral epidermal hyperplasia, gas exchange, oxygen consumption, hyperoxia, salinity tolerance, chloride cell

Effectiveness of Increasing Temperature of Rearing Water and Non-feeding against Viral Endothelial Cell Necrosis of Eel

<>Tanaka Makoto1*, Takayuki Satoh1, Wen-Jun Ma1 and Shin-ichi Ono2<>1Hamanako Branch, Shizuoka Prefectural Research Institute of Fishery, Hamamatsu, Shizuoka 431-0214, Japan
2School of Marine Science and Technology, Tokai University, Shimizu, Shizuoka 424-8610, Japan
(Received March 10, 2008)
ABSTRACT遊iral endothelial cell necrosis of eel (VECNE) of Japanese eel Anguilla japonica, caused by an adenovirus (JEAdV), has been a serious problem of aquaculture industry in Japan. In the present study, effectiveness of increasing water temperature and non-feeding against VECNE was evaluated. Cumulative mortalities of fish intraperitoneally injected with 105.05 TCID50/fish of JEAdV increased with elevating water temperature in the range between 20゚C and 31゚C, but mortality at 35゚C was as low as that at 20゚C. Rearing infected fish under the non-feeding condition further enhanced the effect of treatment at 35゚C. The effectiveness was dependent on rearing periods at the high temperature; more than 3 days at 35゚C were needed to reduce mortality. Fish, which survived the primary challenge with JEAdV at 35゚C, showed high resistance to re-challenge with JEAdV. From these results, the treatment of fish under the non-feeding condition at 35゚C is useful to control VECNE.

Key words: viral endothelial cell necrosis of eel, adenovirus, Japanese eel, water temperature, non-feeding

Effect of Water Temperature on Mortality and Virus Shedding in Carp Experimentally Infected with Koi Herpesvirus

<>Kei Yuasa1*, Takafumi Ito2 and Motohiko Sano1<>1National Research Institute of Aquaculture, Fisheries Research Agency, Minami-Ise, Mie 516-0193, Japan
2Tamaki Station, National Research Institute of Aquaculture, Fisheries Research Agency, Tamaki, Mie 519-0423, Japan
(Received July 13, 2007)
ABSTRACT佑ommon carp Cyprinus carpio were experimentally exposed to koi herpesvirus (KHV) under water temperature regimes ranging from 16゚C to 28゚C. Fish maintained at 16゚C, 23゚C and 28゚C died due to infection at 21-2, 5-20 and 7-14 days post-virus exposure (dpe), respectively. Cohabitation experiments in which KHV-infected common carp were kept with naive koi carp revealed that infectious virus was continuously shed from the infected common carp for 34 days (7-40 dpe) at 16゚C, for 14 days (1-14 dpe) at 23゚C and for 12 days (3-14 dpe) at 28゚C. The relatively extended duration of virus shedding observed at 16゚C suggests the potential risk of infection from fish maintained under low-temperature conditions as a source of viral inocula.

Key words: koi herpesvirus, KHV, carp, water temperature, virus transmission, virus shedding

Estimation of the Time for Nocardia seriolae Infection of Cultured Yellowtail

<>Tomokazu Itano1*, Hidemasa Kawakami1, Tomoya Kono2 and Masahiro Sakai2<>1Ehime Prefectural Fish Disease Control Center, Sakashizu, Uwajima, Ehime 798-0087, Japan
2Faculty of Agriculture, University of Miyazaki, Miyazaki 889-2192, Japan
(Received December 7, 2007)
ABSTRACT輸 study was carried out to estimate the time for Nocardia seriolae infection of cultured yellowtail Seriola quinqueradiata. Yellowtail (58-1600 g in body weight) were collected at two fish farms in Ehime Prefecture from July 2001 to May 2002. Serum antibodies against N. seriolae antigens were detected by indirect enzyme-linked immunosorbent assay (ELISA). A significant increase in the serum antibody level was first recognized in August 2001, and high antibody levels were maintained in fish of both farms. Outbreaks of nocardiosis in the farms initiated in September or October and terminated in November. These results suggest that infection of N. seriolae in yellowtail began between July and August.

Key words: Nocardia seriolae, Seriola quinqueradiata, nocardiosis, antibody, ELISA

Proliferative Branchitis Associated with Pathognomonic, Atypical Gill Epithelial Cells in Cultured Ayu Plecoglossus altivelis

<>Shinpei Wada1*, Osamu Kurata1, Kishio Hatai1, Hideo Ishii2, Kohichi Kasuya2 and Yuhsuke Watanabe2<>1Laboratory of Fish Diseases, Nippon Veterinary and Life Science University, Musashino, Tokyo 180-8602, Japan
2Tochigi Prefectural Fisheries Station, Ootawara,Tochigi 324-0404, Japan
(Received February 18, 2008)
ABSTRACT悠n 1998 and 1999, severe episodes of mortality, often reaching 90%, were recorded among cultured populations of ayu Plecoglossus altivelis reared in Japan. The diseased fish showed appetite reduction and abnormal swimming behavior. Histopathological examination revealed proliferative branchitis with enlarged and atypical epithelial cells. Abundant electron-dense, virus-like particles were observed within the cells under transmission electron microscopy. The particles had a cocoon-like shape and ranged in length from 200 to 300 nm, indicating a member of the poxvirus group. These findings suggest the possibility that the mortality events are related to infection of a poxvirus-like virus.

Key words: Plecoglossus altivelis, proliferative branchitis, poxvirus-like virus