Both orally immunized ayu, Plecoglossus altivelis, and control fish were challenged with organism, Vibrio anguillarum, by three ways. First, fish were exposed to organisms discharged from naturally infected fish for 24 hours. Organisms were isolated at high percentage from almost all part of body in the control fish, while the isolation rate was low particularly on the body surface in the immunized fish. Secondary, fish were bathed in bacterial suspension of a concentration of 107 cells per milliliter for 15 minutes. Twenty four hours after challenge organisms were isolated from the skin of the control fish, then the number of organism increased gradually for the next 72 hours. No organism was detected from the intestine and contents of it in both groups or the skin in the immunized group. Finally, fish were injected intramuscularly resulting almost equal mortality in both groups. Agglutinin titer in the body surface mucus rose to 1: 64 in the immunized group, but did not in the control group. Agglutinin titer in neither sera nor intestinal mucus rose in both groups. The body surface mucus of the immunized fish prevented organisms from adhering to the skin more effectively than that of the control fish. From these results it is assumed that the defense effect by the oral immunization is attributed mainly to the agglutinin secreted in the body surface.
The authors demonstrated that nutritional myopathy in cultured young puffers (Fugu rubripes) was characterized by the alterations of the striated musculature and ceroid deposition in visceral organs. The causes of this disease were assumed to be the poisoning of the rancid fish-oil and vitamin E deficiency (ENDO et al. 1979). In this study a prophylactic effect of vitamin E (α-tocopherol acetate) on the myopathy was tested by administrations at following levels per the 100 g of sandeel mince; 500 mg in the first group, 250 mg in the second group, 200 mg with vitamin mixture in the third group, 100 mg with vitamin mixture in the forth group and 0 mg in the control group. 5000 puffers (0.3 g mean body weight, 24.6 mm mean body length) were maintained in the each group for 50 days (water temp. 22.2-30.9°C). Growth ratios on the 50th day increased significantly with increasing the amount of vitamin E.. Fish underwent the myopathy were encountered in the third and forth groups and control. However, no fish manifested the myopathy in the first and second groups. From the results of present examination, it was determined that the high levels of vitamin E prevented from the occurrence of the myopathy and it may be thought that the myopathy was due to vitamin E deficiency.
During the period from July 1976 through September 1977, epizootics occurred among cultured yellowtail, Seriola quinqueradiata, and red sea bream, Chrysophrys major, in Kochi and Kagawa Prefecture. The typical symptoms of this disease were exophthalmos and occasionally congestion and swallen lesion on the caudal peduncle. Organisms could be isolated from diseased fishes. In the present paper, morphological, biological and biochemical characteristics of six organisms isolated from diseased yellowtail and red sea bream were examined and these organisms were classified by BAIRD-PARKER'S biochemical subgrouping scheme. The organisms were gram-positive, non-motile, spherical cells of about 0.6-1.8 μm in diameter occurring singly, in pairs and irregular clusters. Catalase production and glucose fermentation were positive, oxidase and coagulase production were negative, and all organisms except one showed negative reactions in mannitol fermentation. On the basis of these characters, the organisms were identified as Staphylococcus epidermidis; moreover, three organisms isolated from yellowtail were classified as BAIRD-PARKER'S (B-P) Staphylococcus subgroup II, V and VI, and three others from red sea bream were classified as B-P Staphylococcus subgroup II.
In the previous paper, the morphological, biological and biochemical properties of the organisms isolated from diseased yellowtail, Seriola quinqueradiata, and red sea bream, Chrysophrys major, had been investigated, and the isolates were identified as Staphylococcus epidermidis. In this study, the serological properties of the organisms isolated from diseased yellowtail, red sea bream and ell, Anguilla japonica, were investigated by cross-agglutination test, cross-absorption test and gel precipitation tequnique. Also the influence of the incubation period and temperature, and heating on agglutination were examined. The results are summarized as follows : 1. The common antigens were recognized among the isolates by agglutination and precipitation techniques. All isolates were found to be polyvalent in antigenic composition. 2. Incubation period and temperature of the isolates didn't influence on the agglutination of the major antigens on the isolates. 3. Some isolates which failed to agglutinate in live condition were observed to agglutinate in antisera after heating. 4. On the basis of the results, the isolates except SHy-1 were divided into 5 serotypes from A to E as follows: type A, 110-1; type B, 110-2; type C, 110-3, 110-4, 110-5, 110-8, M110-1 and SHy-2; type D, 110-6 and 110-7; type E, K110-1.
In the previous papers, the organisms isolated from diseased fishes had been identified as Staphylococcus epidermidis and the serotyping in them was reported. In this paper, the serological relationship between the isolates and Tachikawa strains was investigated by cross-agglutination test, cross-absorption test and gel precipitation technique. The common antigens were observed between the isolates and Tachikawa strains. All isolates except 110-2 and K110-1 were considered to differ from Tachikawa strains in antigenic patterns examined by agglutination techniques. The factor sera which had been previously prepared against the isolates reacted with the hetelogous antigens of Tachikawa strains. All isolates except 110-2 and K110-1 formed the precipin lines different from Tachikawa strains. On the basis of the results obtained, it is concluded that the isolates originated from water environment or fishes rather than from human, because the antigenic patterns of the isolates are considered to be different from Tachikawa strains.
Amago salmon Oncorhynchus rhodurus were artificially infected with A. salmonicida, the bacterial agent of the furunculosis of salmonids, and changes in number of red blood cells, hematocrit value, hemoglobin concentration, plasma protein concentration and number of viable cells of inoculated bacteria in various organs were studied. All the fish died until 8 days post inoculation of bacteria. The inoculation produced a furuncle around the site of the injection. However, no severe damage was observed in other organs including the intestine. Number of red blood cells, hematocrit value, hemoglobin concentration and plasma protein concentration showed a tendency to decrease at 3 or 4 days post inoculation of bacteria. A. salmonicida was reisolated from all the organs examined of moribund fish inoculated with the bacteria. The number of viable cells in the liver and kidney were found around 1078 cells/g wet tissue.
Recently a mortality has occurred in sea bass, Lateolabrax japonicus, transferred from Korea and cultured at a fish farm in Goto, Nagasaki Prefecture. The main symptoms of this disease are circular swimming movement, whirling and extremely swelled air bladder. The results of bacteriological observations were negative. However, a myxozoan spores was found in every parts of the brain of the fish. They were characterized by the six to eight polar capsules (Fig. 1). Trophozoites were not observed. It closely resembles to Hexacapsula neothunni ARAI and MATSUMOTO, 1953 found in a jellied condition of the body muscles in yellowfin tuna, Thunnus albacores, but can be distinguished from it by the number and size of polar capsules and the site of infection. Later, the identical spores were also found in the brain of the other marine cultured fish, Japanese striped knifejaw, Oplegnathus fasciatus and yellowtail, Seriola quinqueradiata.
The parasite reported in the above article was misidentified, which was pointed out by Dr. K. MUROGA and Mr. Do of Hiroshima University and Dr. J. S. Ho of California State University. Reexamination by Dr. Kunihiko IZAWA of Mie University upon my request has revealed that it is a copepodid larva belonging to the Caligoida.