• Journal of fish pathology
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• v.9 no.1
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• pp.33-40
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• 1996

A filamentous form of mollicute-like bacterium was detected during a routine health survey of wild adult kuruma shrimp Penaeus japonicus. The kuruma shrimp were native to Japan and were imported to Korea. The histology showed no pathological changes. Transmission electron microscopy revealed extensive infections of hepatopancreatic epithelial cell by a pleomorphic, filamentous intracellular bacterium. The filamentous bacterium was of about 60 nm in diameter and 300 nm to more than $1{\mu}m$ in length. Teh morphology of bacteria were filamentous and branched with terminal blebs, or knobs, on the branches. They lacked the cell wall, and were bounded by the plasma membrane. They contained typical prokaryotic ribosomes and fibrillar DNA-like strands. No additional internal structure has been observed. They are considered to be mollicutes, based upon the morphological appearance and upon the cellular location.

• Fisheries and Aquatic Sciences
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• v.3 no.3_4
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• pp.188-194
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• 2000

A protease purified from hepatopancreas of shrimp, Penaeus japonicus, had maximum activity at $70^{\circ}C$ and in neutral and alkaline pH ranges. Specific activity at optimum reaction condition of the protease was estimated to be approximately 12 U/mg/min. The protease was stable in neutral and alkaline pH ranges and activity was retained after heat treatment at $50^{\circ}C$ for 30 min. Apparent $K_m$ and $V_{max}$ value against casein substrate were estimated to be $0.29\%$ and $7.8see^{-1}$, respectively, and those against N-CBZ-L-tyrosine p-nitropheny1 ester (CBZ­Tyr-NE) were 0.38 mM and $2,400 see^{-1}$, respectively. The N-termina1 sequence of the protease showed high homology to the trypsin from same species and the proteases from shrimp. Myosin heavy chain (MHC) from shrimp tail meat was the most susceptible to the protease and actin/tropomyosin were degraded progressively during 4 hr incubation, but to a lesser degree than MHC.

• Journal of fish pathology
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• v.13 no.1
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• pp.15-20
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• 2000

Infection rates with white spot baculovirus(WSBV) in wild-caught shrimp spawners appeared to be 52% in Penaeus chinensis and 20% in Penaeus japonicus when diagnosed by polymerase chain reaction (PCR). Infection rates of WSBV from inhabitant organisms in shrimp farm showed 37% in Upogebia major and 29% in Calliamassa japonica. The viruses maintained their survivorship in seawater at $4^{\circ}C$, but lost it at $25^{\circ}C$.

• Journal of Microbiology and Biotechnology
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• v.11 no.3
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• pp.394-398
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• 2001

Because of the great concern over the possibility of contamination from the rod-shaped nuclear virus (PRDV) from Japan and white spot virus (WSSV) from Taiwan, most eggs used in Korean shrimp farms are currently obtained from local broodstock. In addition, the screening of imported broodstock for any viral presence at the National Fisheries Research and Development Institute is also mandatory. Nonetheless, massive mortality from white spot syndrome continues in Korea. In the present study, we present an improved PCR method to use tissue-extracted DNA instead of viral DNA extracted from a purified virus based on a sucrose density gradient, and produced results within 8 h. In 1998, this modified PCR method was able to detect that diseased Penaeus japonicus were infected within 8 h. In 1998, this modified PCR method was able to detect that diseased Penaeus japonicus were infected only with PRDV, while Fenneropenaeus chinensis were infected with both PRDV and WSSV. In 1999, PRDV and WSSV were detected in F. chinensis with signs of infection, but not with WSSV alone.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.13 no.3
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• pp.121-124
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• 1980

Microscopical studies of Leucothrix sp. and its histological effect on the gill tissue of Penaeus japanicus have been made. Infection of Leucothrix sp. results in color change of the gills of the shrimp which is mainly due to the brown or black pigments of the filamentous bacteria. Higher degree of the infections makes necrosis and serious histological changes of the gill tissue and this infection affects the respiratory activity of the shrimp.

• Journal of fish pathology
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• v.14 no.1
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• pp.11-15
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• 2001

For the production of healthy shrimp(Penaeus chinensis, Penaeus japonicus) seedlings free from the white spot baculovirus(WSBV), we tried to disinfect shrimp eggs with iodine. A relative hatching rate of over 50% has resulted from the treatments of fertilized eggs of fresh shrimps(P. chinensis) with an effective povidon-iodine concentration of 20-200 ppm for 30 seconds and 60 seconds, respectively. The 60 sec treatment group with a 20 ppm effective povidon-iodine concentration showed nearly a 50% relative hatching rate. The over 50 ppm treatment group, however, did not result in hatching show a relative hatching rate. These hatching rates were similar to those in the fertilized eggs of kuruma prawns treated with povidon-iodine solutions. In case of washing fertilized eggs with UV-irradiated seawater 33.3% relative hatching rate in fresh shrimps was much lower than 55.2% in kuruma shrimps. Treatment fertilized eggs of 2 species of shrimp with 200 ppm iodine for 30 sec did not affect the survival rate of the larvae until the early stage of the post larvae even though the hatching rates were low. In order to produce healthy shrimp seedlings non-infected by WSBV, the shrimp eggs should be washed with UV-irradated seawater and sterilized with a low povidon-iodine concentration for a short time.

• Proceedings of the Korean Aquaculture Society Conference
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• 2004.05a
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• pp.276-277
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• 2004

• Korean Journal of Fisheries and Aquatic Sciences
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• v.30 no.1
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• pp.88-94
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• 1997

The mitochondrial DNA (mtDNA) restriction fragment length polymorphi는 (RFLPs) of five populations were analyzed to delineate the stocks of Penaeus chinensis (Osbeck) in the Yellow Sea. Comparison of P. chinensis with P. japonicus to clarify the nucleotide divergence between two species was also carried out. Based on the fragment patterns, three composite haplotypes were analyzed in P. chinensis mtDNA as four naplotypes were in P. japonicus. Most individuals of each P. chinensis population are shared by one dominant haplotype. Another two haplotypes haying variations at the C/a I and hull sites were also distributed evenly in the Korean and Chinese populations. It is suggested that the gene exchange occurring between populations in the Yellow Sea is frequent. Average length of the mtDNA molecule was estimated to be about 16.44 kb in P. chinensis and 16.31 kb in P. japonicus, Sequence divergence (p) of mtDNA between two species estimated by using Upholt's (1977) fomula was $13.7\%$.

• Journal of Food Hygiene and Safety
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• v.38 no.6
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• pp.496-507
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• 2023

This study investigated species identification and labeling compliance of 48 shrimp products sold in the Korean online markets. Species identification was conducted using the standard DNA barcoding method, using the cytochrome c oxidase subunit I gene. The obtained sequences were compared with those deposited in the NCBI GenBank and BOLD Systems databases. Additionally, phylogenetic analysis was performed to further verify the identified shrimp species. Consequently, 16 shrimp species were identified, including Penaeus vannamei, Pandalus borealis, Palaemon gravieri, Leptochela gracilis, Penaeus monodon, Pleoticus muelleri, Metapenaeopsis dalei, Euphausia pacifica, Lebbeus groenlandicus, Trachypenaeus curvirostris, Argis lar, Metanephrops thomsoni, Metapenaeopsis barbata, Alpheus japonicus, Penaeus chinensis, and Mierspenaeopsis hardwickii. The most prevalent species was Penaeus vannamei, found in 45.8% of the analyzed products. A significant mislabeling rate of 72.9% was found; however, upon excluding generic names such as shrimp, the mislabeling rate reduced to 10.4%. The mislabeling rate was higher in highly-processed products (89.3%) compared with that in minimally-processed products (50%). No correlation was found between the country of origin and mislabeling rate. The results of this study provide crucial data for future monitoring of shrimp products and improving the labeling of shrimp species in Korea.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.3 no.4
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• pp.219-227
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• 1970

The shrimp fishery for Penaeus japonicus on the Koje-Do coast commences in May and continues to October. The best catches are made twice a year, namely June and September. Modal carapace length for the female is $51\~55\;mm$ in May, $51\~60\;mm$ in June occupying about 80 percent of the total catch. There is conspicuous mode in July and $46\~50\;mm$ in August. Modal carapace length for the male is $41\~45\;mm$ in May, $46\~50\;mm$ in June, $41\~45\;mm$ in July and August. The stock of p. japonicus can be divided into two groups, namely, spring and fall groups. Among samples of p. japonicus during the period from May through August the sex ratio consisted of about 33 percent females and 67 percent males, showing wide departure from a 1:1 ratio. The relationships between carapace length ($\iota$), body length (L) and body weight (W) are expressed by the following formulae : $$L=2.9418{\iota}+2.0166$$, $$W:1.449{\iota}^{2.2858}$$ (Mayssample) $$L=2.5551{\iota}+4.2986$$, $$W=1.528{\iota}^{2.2595}$$ (June sample) $$L=2.6738{\iota}+3.4037$$, $$W=1.341{\iota}^{2.3598}$$ (July sample) The relatlonship between carapace length ($\iota$) and ovary weight (W) is shown as follows: $W=2.695\times10^{-3}\iota^{4.2973}$ for May, June and July Samples.