Nam-Sil Lee

Characterization of virus distribution in Rock Bream (Oplegnathus fasciatus; Temminck and Schlegel) infected with megalocytivirus.

The distribution of virus-infected cells in the organs of Rock Bream naturally infected with megalocytivirus is reported. Examination of sections of liver, spleen and kidney stained by haematoxylin and eosin (HE) and periodic acid Schiff (PAS) revealed the presence of swollen and degenerate cells having morphology consistent with leucocytes. Many of these cells were shown to contain viral DNA by in-situ hybridization (ISH). Cells containing viral DNA were also found in the connective tissue of other organs in which there was no prominent infiltrate of degenerate leucocytes. Viral DNA was also found in the cytoplasm of leucocytes in blood smears. Transmission electron microscopy (TEM) confirmed the presence of viral particles in the cells within tissue and free within blood. The tissue distribution of virus in this infection is suggested to reflect the infiltration of virus-infected leucocytes.

An immune responsive complement factor D/adipsin and kallikrein-like serine protease (PoDAK) from the olive flounder Paralichthys olivaceus.

The cDNA encoding of a complement factor D/adipsin and kallikrein-like serine protease, designated PoDAK, was isolated from the olive flounder Paralichthys olivaceus. PoDAK cDNA encodes a polypeptide with 277 amino acids containing conserved catalytic triad residues of serine proteases. The amino acid sequence of PoDAK showed high similarity to the kallikrein-like protein of medaka, mammalian adipsin/complement factor D and tissue kallikrein homolog, KT-14 of trout, complement factor D of zebrafish, and shared 31.6-36.8% homology with complement factor D/adipsin known from other species, including mammals. Phylogenetic analysis revealed that PoDAK clustered with the kallikrein-like protein of medaka and mammalian adipsin/complement factor D and tissue kallikrein homolog KT-14 of trout. The expression of PoDAK mRNA was high in the gills and heart, moderate in muscle, liver, intestine, stomach, kidney, and spleen of healthy flounder, and increased in the kidney, liver, and spleen of flounder challenged by the viral hemorrhagic septicemia virus (VHSV) or Streptococcus iniae. In situ hybridization confirmed that PoDAK mRNA is localized in the kidney and heart of individuals infected with VHSV. Further investigations are needed to clarify the function of PoDAK in vivo and in vitro.

Non-specific Defensive Factors of the Pacific Oyster Crassostrea gigas against Infection with Marteilioides chungmuensis: A Flow-Cytometric Study

In order to assess changes in the activity of immunecompetency present in Crassostrea gigas infected with Marteilioides chungmuensis (Protozoa), the total hemocyte counts (THC), hemocyte populations, hemocyte viability, and phagocytosis rate were measured in oysters using flow cytometry. THC were increased significantly in oysters infected with M. chungmuensis relative to the healthy appearing oysters (HAO) (P<0.05). Among the total hemocyte composition, granulocyte levels were significantly increased in infected oysters as compared with HAO (P<0.05). In addition, the hyalinocyte was reduced significantly (P<0.05). The hemocyte viability did not differ between infected oysters and HAO. However, the phagocytosis rate was significantly higher in infected oysters relative to HAO (P<0.05). The measurement of alterations in the activity of immunecompetency in oysters, which was conducted via flow cytometry in this study, might be a useful biomarker of the defense system for evaluating the effects of ovarian parasites of C. gigas.

Effects of Water Temperature and Estradiol-17β on the Sex Ratio and Growth of the Japanese Eel, Anguilla japonica

This study investigated the effects that water temperature and the administration of estradiol-17s (E2) had on the sex ratio and growth of the Japanese eel, Anguilla japonica. Glass eels (total length≒6.5 cm) were differentiated into an E2 group and an E2-free group and then they were reared for about four months at three water temperature levels of 20C, 24C, and 28C. The results showed that the young eels survived normally at the rearing water temperature of ≥24 o C, and grew to a mean size of 20 cm (total length). In the E2-free group, temperature was not found to increase the sex ratio (feminizing rates); however, the sex ratio of the E2-administrated group was found to be a little higher at a high temperature (28C). The growth of the E2 group was lower than the growth of the E2-free group at 24 o C and the E2 concentration levels in the plasma at 24 o C were found to be significant after the end of the E2 administration period (178 days). Therefore, we thought that long-term administration of E2 must be considered to be the reason for growth decline in spite of the prominent sex ratio effect. Our results indicate that temperature was not related to an increase in the feminizing rate (sex ratio) in the Japanese eel, Anguilla japonica, and other environmental factors (rearing density, salinity, etc.) that have the possibility of inducing ovarian differentiation must be investigated.

Artificial Infection with Nocardia seriolae and the Histological Examination at Snakehead Channa argus

Snakehead, Channa argus were intraperitoneally infected with Nocardia seriolae. at the concentrations of 1.5×10 7 cfu/ or 1.5×10

Development Changes in the External Structure of the Head and the Histological Structure of the Eye in Artificially Reared Japanese Eel, Anguilla japonica, Leptocephalus and Glass Eel

Knowledge of morphological changes in eel larvae is very important for artificial rearing of eel larvae. In this study, we investigated the morphological structure of the head region and histological changes of the eye retina in artificially reared larvae at various stages and in glass eel just after metamorphosis. Structural changes were observed in the upper jaw (maxilla) and the lower jaw (mandible) after 100 dah (day after hatchery) and after metamorphosis. Teeth had degenerated by the time of completion of metamorphosis. Major histological changes observed in the eye retina were the formation of the outer plexiform layer and the outer nuclear layer from 100 dah larva and a change in the rod cell layer after metamorphosis. The cornea was not observed at 10 dah in the eel larva. More information is needed on the early developmental stages of eel larvae to enable mass production of glass eels. The results obtained in the present research will be useful when developing novel rearing programs for eel larvae.

Effects of Starvation, Water Temperature, and Water Flow on the Metamorphosis of Leptocephalus of Japanese Eel Anguilla japonica

????????? ?????????(Anguilla japonica)??? ?????? ??????????????? ?????? ????????? 1960?????? ???????????? ???????????????, Yamamoto and Yamauchi (1974)??? ????????? ????????? ???????????? ???????????? ???????????? ??????????????? ?????? ????????? ???????????????, ??? ?????? ?????? ???????????? ????????? 2?????? ??????????????? ???????????????(Yamauchi et al., 1976). ????????? ????????? ????????? ????????? ???????????? ?????? ?????? ????????? ????????? ???????????? 2000?????? ?????? ????????? ?????? ?????????????????? Tanaka ?????? ?????? ??????????????? ????????? ????????? ??????????????? ???????????? ????????????????????? ????????? ????????????????????? ???????????????(Tanaka et al., 2001), 2003 ??? ?????? ?????????????? ????????? ???????????????(Tanaka et al., 2003). ????????? ??????????????? ?????????(A. anguilla), ????????? ?????????(A. dieffenbachia, A. australis) ??? ????????? ?????????(A. rostrata)??? ????????? ??????, ?????? ?????? ??? ?????? ?????? ?????? ??????(????????? 1?????? ??????)??? ?????? ????????? ???????????????(Lockman and Young, 2000; Oliveira and Hable, 2010, Pedersen, 2003; 2004; Palstra et al., 2005). ??????????????? ????????? ??????????????? ???????????? ????????? ?????? ????????? ????????????(Kim et al., 2006a; 2006b; 2007a; 2007b), 2012??? ?????? ????????? ????????? ?????? ????????? ??????????????? ?????????????????? ?????????????????????????????????????????????????????????????????????????????????(Kim et al., 2013). ???????????????????????????????????????????????????????????????????????????????????????????????? 200??????????????????, 15-20????????????????????????????????????????????????????????????????????????????????????(Tanaka et al., 2003; Kim et al., 2013). ??????????????????(Anguilla japonica)?????????????????????, 15 ??N, 140 E ???????????????????????????(Tsukamoto, 1992), ???????????????????????????????????????????????????, ????????????????????????????????????, 21-26 N, 121-129??E ???????????????????????????(Shinoda et al., 2011). ??????????????????????????????????????????????????????????????????????????????????????????????????????????????????(Lecomte-Finger, 1992; Arai et al., 1999; Marui et al., 2001). ?????????????????????????????????????????????????????????????????????????????????????????????????????????, ???????????????????????????????????????????????? , ????????????????????????????????????????????????????????????(Okamura et al., 2012). ?????????????????????????????????????????????????????????????????????