No abstract

Euryhaline teleosts possess excellent adaptability to a wide range of environmental salinities. Although intestinal water absorption is important for seawater (SW) adaptation, little is known about the molecular mechanisms of the water-transporting pathway in the intestine. We have cloned three homologs of the mammalian aquaporins (AQPs) 3, 8 and 10 from the intestine of the SW-acclimated Japanese eel. The deduced amino-acid sequences shared 47-98% homology with other known respective AQP isoforms. Topology prediction of the identified sequences showed six membrane-spanning domains, intracellular N-and C-terminal tails, and two NPA (asparagine-proline-alanine) motifs in the second and fifth connecting loops, all of which are highly conserved among known AQPs. Reverse transcription PCR analysis revealed that AQP3 was expressed in various tissues, whereas the expression of AQP 8 and 10 mRNAs was detected predominantly in the intestine. The expression levels of AQPs 1, 3, 8 and 10 in the anterior and posterior intestines and the rectum were determined by real-time quantitative PCR and compared for FW (freshwater)-and SW-acclimated eels. AQP1 expression levels in the posterior intestine and rectum were significantly higher in the SW-acclimated eel than in the FW-acclimated fish. AQP3 expression in the SW-acclimated eel was only higher in the rectum than that in the FW-acclimated eel. Expression levels of AQPs 8 and 10 in the intestinal segments tended to be higher in the SW-acclimated eel than in the FWacclimated eel. These results showed that intestinal AQP expression is closely related to SW adaptation, suggesting the presence of a water-absorbing mechanism associated with multiple AQP isoforms in the intestinal tract.

-As 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.

No abstract

To determine whether immunization with Microcotyle sebastis antigen could induce protection against the parasite's establishment, naive juvenile rockfish were immunized by injection or immersion with whole worm antigen of M. sebastis. The infestation intensities of immunized groups following a challenge (2 wk after boosting) with 5000 M. sebastis eyed-eggs were significantly lower than those of control groups, when determined 7 wk postinfectlon. The fish in the groups boosted with M. sebastis antigen showed stronger protection than unboosted groups. The control group injected with FCA only showed a significantly smaller number of worms than the control group, which was immersed in PBS containing seawater. The results strongly suggest that both specific and nonspecific immune factors participate in the protection of rockfish against M. sebastis establishment.