• Journal of fish pathology
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• v.13 no.2
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• pp.129-136
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• 2000

To understand host-defence mechanism of clam(Ruditapes philippinarum) hemocyte against foreign materials, classification and their seasonal change in the number were performed. clams collected from a farm in Julpo Bay, Gochang, Chollabuk-Do were used in this experiment. Lots of hemocytes were found between the muscle fibers and connetive tissue of posterior adductor muscle. Hemocytes of R. philippinarum were classified into granulocytes and agranulocytes. Granulocytes were composed of three types, basophilic granulocyte, acidophilic granulocyte and fibrocyte in accordance with the staining affinities of their cytoplasmic granules. Fibrocyte has filopodia and vesicle in endoplasm and bigger than other granulocytes in size. Agranulocytes were less in the number and smaller in the size compared to those of granulocytes. Hyalinocytes had no granule in their cytoplasm. The nucleus located in the center of the cell was oval or spherical shaped. In electron microscopic observation, granulocytes and hyalinocytes contained electron-dense vesicles and some small lucid vesicles in their cytoplasm, respectively. Granulocytes phagocytosed more zymosan particles than hyalinocytes. Acidophilic granulocytes showed higher phagocytic ratio than basophilic granulocytes. Total hemocyte numbers showed the highest at April to August and the lowest at October to December. In the composition of each hemocyte, basophilic granulocytes were always more than acidophilic granulocytes and hyalinocytes.

• Journal of fish pathology
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• v.8 no.1
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• pp.57-67
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• 1995

Twenty-four hours, acute toxicity and the histopathological effect of formaline to flounder, Paralichthys olivaceus larvae were examined. The $LC_{50}$ values obtained to farmaline were 2,520 ppm in 1 hour treatment. 1.610 ppm in 2 hours treatment, 868 ppm in 4 hours treatment and 141 ppm in 24 hours treatment. Many pathological features such as hypertrophy of mucous and epithelial cells in secondary gill lamella, hyaline droplet degeneration of tubular epithelial cells in the proximal convoluted segment of renal tubules, focal or massive necrosis in liver cells and pycnotic nucleus in heart cells were recognized. The above results were discussed in relation to the application of formaline as therapeutic agent in flounder disease.

• Journal of fish pathology
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• v.23 no.3
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• pp.293-302
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• 2010

Effects of formalin on removal of Pseudodactylogyrus spp. were examined against naturally infected eel, Anguilla japonica (weight 89.9~96g) at a water temperature of $28^{\circ}$. Prior to experiments for removal of the parasite, the hematological toxicity of formalin bath at 0~500 ppm for 30 min~24 h was assessed by hematocrit values (Ht). Based on the results of Ht, appropriate methods of treatment, concentrations and durations, were examined in the main study. There was no significant (P>0.05) change of Ht in 100 to 200 ppm for 24 h. In contrast, Ht increased significantly (P<0.05) at above 300 ppm. This suggests that physiological damage was caused by formalin bath treating with 300 to 500 ppm. Formalin bath with 100 and 200 ppm for 24 h caused significant decreases (P<0.05) in the infection of the parasite. In conclusion, the 100 ppm formalin for 24 hour-bath was found most recommendable for the effective treatment of Pseudodactylogyrus spp. for the gills of the infected eel because of the median lethal concentration ($LC_{50}$) of formalin to eel; cumulative mortalities were found to be 0 and 13.3%, respectively, following 24 h bathing.

• Proceedings of the Korean Aquaculture Society Conference
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• 2003.10a
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• pp.44-44
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• 2003

Gene expression in five tissues of the abalone (Haliotis discus hannai) was investigated using an expressed sequence tag (EST) analysis. Randomly selected clones were obtained from cDNA libraries constructed with gill (GI), digestive diverticula(DD), hepatopancreas (HP), foot/mucus (FM) and rectangular muscle (RM). Of 1,235 clonesanalyzed (288 clones for GI, DD, HP each,166 for FM, and 205 for RM), 741 (60.0%) clones in total turned out to share significant similarity with the sequences from NCBI GenBank (less than 10/sup -3/ of e-values), 423 sequences showed poor similarity (> 10/sup -3/), and 71 sequences didn't match with any sequences in GenBank. The percent unique sequence (singleton) was ranged from 56.1% (RM) to 74.7% (FM) among libraries. On the other hand, overall percent singleton was 55.3% when all the ESTs from five libraries were assembled into contigs. Analysis of the organisms represented by the best hit for each EST (e-values < 10/sup -3/) showed that 23.8% matched with mammalian entries, 24.0% with mollusks, 14.4% with insects, 11.6% with fish and 26.2% with others. The expressed patterns differed among the tissues when judged by the categorization of the sequences from each library into 10 broad functional classes. In all the libraries, the class I (no hit o. poor similarity) was the largest category with an average of 40.1%. This largest class was followed by class V (general metabolisms) in DD (21.9%), GI (14.6%) and HP (16.7%), while the 'cell structure and motility'(class VI) was the second largest class in remaining two libraries (31.2% for RM and 9.6% for FM). The class IX (cell division and proliferation) was the smallest class in all the libraries (less than 3%). This report provides the first tissue-specific lists of expressed abalone genes, which could be a fundamental basis for genomics program of abalone species.

• Journal of Aquaculture
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• v.15 no.1
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• pp.7-13
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• 2002

Since 1993, the White Spot Syndrome Virus (WSSV) disease occurred in China among cultured shrimps resulting in mass mortality. Epizootiological surveys undertaken during the outbreak period of 1993-1994 indicated that all stages of Penaeus chinensis, P. japonicus and P. monodon were infected. Consequent to the transport of contaminated shrimp seedlings and seawater, the disease spread all over the farms of China. The disease was more rapidly transmitted at temperatures above $25^{\circ}C$. Challenge experiments showed the causative agent was highly virulent. White spots appeared on the carapace of both span-taneous and experimentally infected shrimps. Moribund shrimps contained turbid hemolymph, hypertrophied Iymphoid organ and a necrotic mid-gut gland. Electron microscopy showed the presence of viral particles in the gills, stomach, lymphoid organ, and epidermal tissue of the infected shrimp. The visions were slightly ovoid with an envelope and averaged 350 $\times$ 150 nm; nucleocapsids measured 375 $\times$ 157 nm. With discontinuous sucrose gradient of 35, 50 and 60% (w/v), the virus was separated from hemolymph of the infected shrimp. The estimated molecular weight of genomic DNA was 237 Kb with EcoR I, 247 Kb with Hind III and 241kb with Pst I. A total of 9 hybridoma colones secreting monoclonal antibodies (MAbs) were produced from mouse myeloma and spleen cells immunized with WSSV. The immunofluorescence assay of gill tissue showed that the MAbs reacted with diseased but not with healthy shrimp. The MAbs belonged to IgGl, IgG2b subclass and IgM class, all with kappa light Immune-electron-microscopy with colloidal gold marker showed the presence of 5 MAbs epitopes on the envelope and one on the capsid of the virus. Baculoviral mid-gut gland necrosis showed the specificity of the MAbs produced. For diagnosis 5 different methods were selected. Using Kimura primers for PCR, or MAbs for immunoblot, ELISA or FAT method, in situ hybridization was carried out to show the gene. All these methods detected WSSV in the organ samples of the diseased shrimp but not in healthy one.

• Parasites, Hosts and Diseases
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• v.23 no.1
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• pp.18-23
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• 1985

The infection stasus of the loaches, Misgurnus anguillicaudatus, with the metacercariae of Echinostoma hortense, was studied in Korea. A total of 154 loaches purchased at 4 local markets (Seoul, Kimhae, Naju-gun and Kangjin-gun) were examined their infection rate as well as the density and location of the metacercariae in the fish body. The results are as follows: 1. The loaches carrying the metacerariae of E. hortense were 64 (41.6%) in total number and the metacercarial density ranged 1-29 per infected loach with an average value of 8.1. The highest infection rate and metacercarial density were obtained from the loaches purchased at Kangjin-gun, Jeonranam-do. 2. The metacercariae of E. hortense were chiefly distributed in the distal intestinal wall and the adjacent mesentery, the perianal tissues, and the head and gill of the loaches examined. From the results, it is concluded that the loach is one of the important second intermediate hosts of E. hortense in Korea, and their infection rate and metacercarial density are considerably high.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.46 no.4
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• pp.445-453
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• 2013

Walleye pollock Theragra chalcogramma fisheries in Korean waters have changed dramatically during the last three decades: the highest catches occurred in 1981, followed by continuous decreases through the 1990s, ending with a complete collapse of the population in the 2000s. The major spawning ground of walleye pollock is located in North Korean waters, and some juveniles (called nogari in Korean, <300 mm) migrate to the south for feeding and growth. Since the 1960s, Korean fishermen have often caught juveniles, and the weight (metric tons) of juvenile catch was recorded from 1975-1997. However, because the walleye pollock were not aged, the population age structure was not delineated. We developed a model to estimate the number of walleye pollock of each size class based on catch statistics of adults and juveniles, the catch proportion of each size class, and length and weight information on specimens collected by Danish-seine and drift-gill-net fisheries. The model results demonstrated that the recruitment size of walleye pollock was consistently within the 200-250mm size class, and the highest number of this size class occurred in 1981, although values greatly fluctuated interannually. The number of juvenile pollock was 10.4 times higher than that of adult pollock during 1975-1997. The total yield of juvenile pollock was 0.95 million tons, which was equivalent to about 68.2% of total pollock production. The number of juvenile pollock caught during the same period, however, was 16 billion, comprising about 91.2% of the total number caught. Such high fishing pressure on juvenile pollock is considered one of the main factors causing the collapse of the pollock population.

• Journal of Aquaculture
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• v.11 no.2
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• pp.223-230
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• 1998

This study was carried out for the purpose of developing environmental friendly and effective chemical treatment method for the disease control in the land-based flounder culture which is industrially popular in the coastal area in Korean. The chemicals such as flounder, Paralichthys olivaceus and their effects on the fish based on the 24hr-$LC_{50}$, $LT_{50}$, 24-hour survival rate at each experimental concentration, recovery rate of the survived individual from chemical treatment, and the histological change of the gill after chemical treatment were investigated and analyzed. The 24hr-$LC_{50}$ was 321.65 ppm for formalin, 419.62 ppm for chlorine dioxide, and 395.97 ppm for hydrogen peroxide, respectively. The $LT_{50}$ was 15-hour for formalin, 17-hour for chlorine dioxide and 24-hour for hydrogen peroxide, respectively. Fishes exposed to the experimental concentration of three chemicals were quickly susceptible in the order of formalin, chlorine dioxide and hydrogen peroxide with a trend of shorter half lethal time at higher concentration. Initial survival rate of the flounder soon after chemical treatment was the highest in the hydrogen peroxide treatment compared with the other two chemicals. The histological damage by the hydrogen peroxide treatment was negligible compared with the other two chemicals. Accordingly, hydrogen peroxide treatment showed the lowest toxicity compared with the other two chemicals to the experimental fishes.

• Korean Journal of Ichthyology
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• v.29 no.4
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• pp.258-260
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• 2017

The morphomeristic features of Gadus macrocephalus was compared using fish samples from Jinhae Bay in the South Sea and Boryeong in the Yellow Sea, Korea. In total, 332 individuals were sampled from 2 locations to investigate the differences in the morphomeristic features and determine applicability of it as a means of stcok discrimination of G. macrocephalus. No significant differences in the number of vertebrae, 1st to 3rd dorsal-fin soft rays, 1st and 2nd anal-fin soft rays, pectoral-fin soft ray, pelvic-fin soft ray, and gill raker were found between two populations from Jinhae Bay and Boryeong. The results of present study revealed that morphomeristic features of G. macrocephalus was not applicable for stock discrimination.

• Korean Journal of Ichthyology
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• v.29 no.4
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• pp.272-276
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• 2017

This is the first report of Cantherhines pardalis (Tetraodontiformes: Monacanthidae) from Korea. A single specimen (105.4 mm in SL) was collected from the coastal waters of Busan by gill net on 20 June, 2012. This species is characterized by having the following morphological traits: II, 34 dorsal fin rays; 31 anal fin rays; 13 pectoral fin rays; caudal peduncle without large spines; spine row on the lateral side of first dorsal spine distinct; posterior end of pelvic with encasing scales distinctly more protruding than ventral flap. This species is similar to C. dumerilii except for the number of spines on caudal peduncle (none in C. pardalis vs. two pairs in C. dumerilii). Based on morphological and molecular approaches, the specimen was identified as C. pardalis. We add C. pardalis to Korean fish fauna and propose the new Korean names "Yuk-gak-mu-nui-jwi-chi" for the species.