• Journal of fish pathology
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• v.9 no.2
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• pp.169-176
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• 1996

An indirect double antibody enzyme-linked immunosorbent assay (ELISA) was developed for rapid detection of a new virus isolated from abnormally swimming salmonid fish, RVS (Retrovirus of salmonid). Results using brain tissue homogenates, and infected cell cultures are described. The sensitivity of the methods is $10^{2.6}$ $TCID_{50}/100{\mu}l$ of the examined cell culture fluid. The specificity was confirmed by the ELISA inhibition test and virological examinations. Viral antigen could be detected in artificially infected fish tissue homogenates. The assay will allow the diagnosis of RVS-infected fish within a day.

• Journal of fish pathology
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• v.31 no.2
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• pp.57-70
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• 2018

Infection with salmonid alphavirus (SAV) is a serious disease that mainly affects rainbow trout (Oncorhynchus mykiss) and Atlantic salmon (Salmo salar L.) reared in seawater or freshwater. SAV is prevalent in European countries including Norway that exports rainbow trout and Atlantic salmon to Korea. Consequently, SAV was listed as a disease notifiable to the OIE and many salmonid-producing countries either designate SAV as their notifiable disease or do research on the development of diagnosis and epidemiology to reduce the possibility of SAV infection. Unlike other salmonid-producing countries, SAV is not listed as a notifiable disease in Korea, thereby arousing concern that SAV will get into the country through the importation of live salmonids. Under the circumstance, Korea needs to have a legal basis to take much stricter follow-up measures, including listing SAV as a notifiable disease, establishing surveillance system based on OIE standards to declare Korea free from SAV, killing infected fish and conducting fallow system against affected farms.

• Journal of fish pathology
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• v.9 no.2
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• pp.177-183
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• 1996

A new RNA virus isolated from abnormally swimming behavior has caused mortalities in salmonid fish (Oh et al., 1995 a), A reverse transcriptase (RTase) activity of the virus was determined by using poly r(A) : oligo d(T) as templete : primer. This RTase activity was associated with virus particles of buoyant density of 1.16 g/ml. The virus particles in sucrose fractions were enveloped and were about 85 nm diameter with central electron-dense core. The brain and kidney samples of artificially infected fish showed RTase activity. Virus particle associated proteins about 120, 80, 65, 61, 48, 42, 35, 30, 25, 19, and 15 kDa were observed when examined by polyacrylamide gel electrophoresis analysis. This study showed the presence of a new retrovirus in salmonid fish, which tentatively called RVS (Retrovirus of salmonid).

• Journal of Microbiology and Biotechnology
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• v.15 no.3
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• pp.665-671
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• 2005

Initiation and activation of sperm motility are prerequisite processes for the contact and fusion of male and female gametes at fertilization. The phenomena are under the regulation of cAMP and $Ca^{2+}$ in vertebrates and invertebrates. Mammalian sperm requires $Ca^{2+}$ and cAMP for the activation of sperm motility. Cell signaling for the initiation and activation of sperm motility in the ascidians and salmonid fishes has drawn much attention. In the ascidians, the sperm-activating and attracting factors from unfertilized egg require extracellular $Ca^{2+}$ for activating sperm motility and eliciting chemotactic behavior toward the egg. On the other hand, the cAMP-dependent phosphorylation of protein is essential for the initiation of sperm motility in salmonid fishes. A decrease of the environmental $K^+$ concentration surrounding the spawned sperm causes $K^+$ efflux and $Ca^{2+}$ influx through the specific $K^+$ channel and dihydropyridine-sensitive L-/T-type $Ca^{2+}$ channel, respectively, thereby leading to the membrane hyperpolarization. The membrane hyperpolarization induces synthesis of cAMP, which triggers further cell signaling processes, such as cAMP-dependent protein phosphorylation, to initiate sperm motility in salmonid fishes. This article reviews the studies on the physiological mechanisms of sperm motility and its cell signaling in aquatic species.

• Journal of Microbiology and Biotechnology
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• v.13 no.6
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• pp.833-840
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• 2003

Sperm motility of salmonid fishes is suppressed by external $K^{+}$ and initiated by decrease of $K^{+}$ concentration surrounding the sperm. It was shown that the decrease in external $K^{+}$ concentration induced not only the initiation of sperm motility, but also hyperpolarization of the plasma membrane and synthesis of cAMP in the sperm of rainbow trout, steelhead trout, and masu salmon. Inhibitors of $K^{+}$ channels, especially voltage-dependent $K^{+}$ channels, inhibited these three reactions, and the inhibitions were abolished by subsequent addition of a $K^{+}$ ionophore, valinomycin, suggesting that $K^{+}$ efflux through the $K^{+}$ channel contributes to rapid changes in the membrane potential of sperm and cAMP synthesis, thereby resulting in the initiation of sperm motility of salmonid fishes.

• Journal of fish pathology
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• v.30 no.2
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• pp.79-88
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• 2017

At the present, fish farms are suffering a lot of economic losses due to infectious diseases caused by various pathogens including aeromonad. Aeromonad is ubiquitous bacteria that causes infectious diseases. At least 26 species in the genus Aeromonas have been reported to cause fatal infections not only in salmonid fishes, but also in other freshwater and seawater fishes. Molecular techniques based on nucleic acid sequences of 16S rDNA and housekeeping genes can be used to identify the Aeromonas species. In this study, The genus Aeromonas was isolated from salmonid fishes of sixteen fish farms in Gangwon-Do, Korea and phylogenetically identified based on the sequences of 16S rDNA and housekeeping genes for Aeromonad, i.e. RNA polymerase sigma factor ${\sigma}^{70}$ (rpoD) or DNA gyrase subunit B (gyrB). Consequently, 96 strains were collected from Atlantic salmon (Salmo salar), coho salmon (Oncorhynchus kisutch), masou salmon (Oncorhynchus masou) and rainbow trout (Oncorhynchus mykiss), and 36 isolates were identified as the genus Aeromonas by 16S rDNA analysis. Thirty six Aeromonad isolates were further analysed based on rpoD or gyrB gene sequences and found Aeromonas salmonicida (24 isolates), A. sobria (10 isolates), A. media (1 isolates) and A. popoffii (1 isolates), indicating that A. salmonicida is a main infectious bacteria in Salmonid fishes in Gangwon-Do. It was also proved that the phylogenetic identification of Aeromonas species based on the sequences of housekeeping gene is more precise than the 16S rDNA sequence.

• Proceedings of the Zoological Society Korea Conference
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• 1999.04a
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• pp.81.2-81
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• 1999

No Abstract, See Full Text

• The Sea:JOURNAL OF THE KOREAN SOCIETY OF OCEANOGRAPHY
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• v.12 no.2
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• pp.102-111
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• 2007

RAPD analyses using 60 OPERON primers and 13 URPs were performed in order to assess the genetic variation and frequency of polymorphisms in Korean salmonids. RAPDS were very reproducible and most useful at the sub-species level. In RAPD analysis, 138 polymorphic bands were detected between Oncorhynchus masou subspecies and 99 bands were generated in two types of rainbow trout. Estimated genetic distances between O. masou subspecies were 0.28794, and between wild rainbow trout and an albino mutant was 0.22786. Each species of salmonid was well characterized using URP 4R, the obtained bands could be useful as a species specific RAPD markers.

• Journal of Microbiology and Biotechnology
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• v.30 no.10
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• pp.1443-1457
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• 2020

The emergence and spread of antimicrobial resistance in pathogenic bacteria of fish and shellfish have caused serious concerns in the aquaculture industry, owing to the potential health risks to humans and animals. Among these bacteria, Aeromonas salmonicida, which is one of the most important primary pathogens in salmonids, is responsible for significant economic losses in the global aquaculture industry, especially in salmonid farming because of its severe infectivity and acquisition of antimicrobial resistance. Therefore, interest in the use of alternative approaches to prevent and control A. salmonicida infections has increased in recent years, and several applications of bacteriophages (phages) have provided promising results. For several decades, A. salmonicida and phages infecting this fish pathogen have been thoroughly investigated in various research areas including aquaculture. The general overview of phage usage to control bacterial diseases in aquaculture, including the general advantages of this strategy, has been clearly described in previous reviews. Therefore, this review specifically focuses on providing insights into the phages infecting A. salmonicida, from basic research to biotechnological application in aquaculture, as well as recent advances in the study of A. salmonicida.

• Development and Reproduction
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• v.24 no.3
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• pp.241-248
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• 2020

This study used a PCR-based genetic analysis platform to create a hierarchical polar dendrogram of Euclidean genetic distances for two salmonid species, Oncorhynchus mykiss (rainbow trout, RT) and Oncorhynchus masou (masu salmon, MS). The species were distantly related to other fish species based on PCR results from using the designed oligonucleotide primer series. Five oligonucleotide primers were used to generate 330 and 234 scorable fragments in the RT and MS populations, respectively. The DNA fragments ranged in size from approximately 50 bp to more than 2,000 bp. The bandsharing (BS) results showed that the RT population had a higher average BS value (0.852) than that for the MS population (0.704). The genetic distance between individuals supported the presence of adjacent affiliation in cluster I (RT 01-RT 11). The observation of a significant genetic distance between the two Oncorhynchus species verifies that this PCR-based technique can be a useful approach for individual- and population-based biological DNA investigations. The results of this type of investigation can be useful for species safekeeping and the maintenance of salmonid populations in the mountain streams of Korea.