The concept of biological control methods in aquaculture

Microbial techniques of biocontrol using the interaction ofmicroorganisms to repress the growth of deleterious bacteria andviruses were developed. The bacterial strain used in this work alsoimproved the growth of fishes and crustaceans. Using the conceptandprocedures of the biocontrol method described here, the aquacultureproduction became stable and evenincreased.     

Embryonic and morphological development of larvae and juveniles of the Amberjack,Seriola dumerili

Embryonic and morphological development of larvae and juveniles of the amberjack,Seriola dumerili Risso, are described using specimens raised at Yaeyama Station (Ishigaki Island, Okinawa Pref.), Japan Sea Farming Association. The specimens obtained from brood fish (3 females, 3 males) were treated with gonadotropin and spawned on 6th of April 1987. The eggs of amberjack are pelagic, spherical in shape and 1.01–1.17 mm in diameter. The yolk is roughly segmented and has a single oil globule 0.22–0.24 mm in diameter. The perivitelline space is narrow. During development, a few melanophores and no xanthophores were observed on yolk. Hatching took place 35 hrs. 15 min. after spawning out at temperatures 23.1–23.7°C. The newly hatched larvae were 2.84–3.04mm in TL with 27 (13+14) myomeres and an oil globule anteriorly situated beyond the head. 3 days after hatching 4.00 mm TL, the mouth opened. 10 days after hatching 4.26 mm TL, small denticles appeared on the margin of the upper jaw and there were 1 anterior and 2 posterior preopecular spines. At 5.96mm TL, notochord was slightly flexed. Caudal, dorsal and anal fins with rudiments of rays appeared at 8.00 mm TL. The specific numbers of all fin rays and spines were obtained in a juvenile 9.60 mm TL. In a juvenile 34.25 mm TL, 54 days after hatching, the characteristic brown band of amberjack had appeared on head. Some notable changes in relative growth were observed at 5 mm and 15 mm in TL.     

Sequence analysis of the hepatitis C virus genome recovered from serum, liver, and peripheral blood mononuclear cells of infected chimpanzees.

Of 13 different strains of hepatitis C virus (HCV) in the inoculum used, only 1 persisted in human lymphocyte cell lines infected in vitro (N. Nakajima, M. Hijikata, H. Yoshikura, and Y. K. Shimizu, J. Virol. 70:3325-3329, 1996). To determine whether that particular strain (designated H1-2) has a tropism for lymphocytes in vivo, we sequenced hypervariable region 1 (HVR1) of the genome of HCV recovered from the sera, livers, and peripheral blood mononuclear cells (PBMC) of chimpanzees infected with plasma H77, the same inoculum used for the in vitro studies. In the PBMC collected from two chimpanzees during the early phase of infection, H1-2 was detected as the only or predominant HVR1 sequence. H1-2 was also detected in PBMC obtained during persistent infection from a chimpanzee that had been treated with immunosuppressants. From the livers of these chimpanzees, two to six different strains were recovered but H1-2 was not detected. Thus, H1-2 appeared to have an affinity for lymphocytes not only in vitro but also in vivo. In samples collected from a chimpanzee after 6 years of infection, however, such tissue compartmentalization of the HCV genome was not observed; a single strain became predominant in the serum, liver, and PBMC. An HCV strain capable of replicating in both the liver and PBMC probably emerged during in vivo replication and persisted.     

Remarkable papillomas in white sturgeons,Acipenser transmontanus, reared in an aquarium

Papillomatous growths on the ventral surface of the body and paired fins of the white sturgeon,Acipenser transmontanus Richardson, were described histologically with the aid of light and electron microscopy. Contrary to the usual state of intact squamous epithelium being equipped with microridges, no such surface structures were apparent in the papillomatous tissue. The growths appeared to be an aberrant elevations of proliferated dermal tissue, which sustains the hyperplastic Malpighian layer consisting of the stratum spinosum (prickle cell layer) and sbasale. Many intercellular bridges were found, constructed from prominent projections, with distinct demosomes and many tonofilaments. The likely causative agent was mechanical irritation between the small aquarium tank and growing sturgeon, since no viral and/or parasitic inclusion bodies were encountered in the cells.     

Histology of the ink tube and its associated organs in a unicornfish,Eumecichthys fiskii (Lampridiformes)

Histological examination of the ink tube (=sac) and melanoid ink production in the unicornfish,Eumecichthys fiskii (Taeniosomi), were conducted on a female specimen, 1050 mm in total length, caught off Sado Island. Sea of Japan, on 16 December, 1996. The ink tube, apparently derived from a primitive gut, was constructed from the connective tissue capsule, muscularis, submucosa and a single layer of cuboidal cells reminiscent of an intestinal villus. Although the site and process of differentiation of melanoid granules could not be determined. variously-sized melanoid clumps were detect-ed between the spaces of the villus-like cell cords. Melanoid ink excreted from the ink tube was attached to the surfaces of the latter, the intestine and the pouch associated with swim bladder. No ink was encountered in the intestinal canal.