• Korean Journal of Fisheries and Aquatic Sciences
• /
• v.47 no.3
• /
• pp.247-254
• /
• 2014

To investigate the acquisition of quinolone resistance, we examined mutations in the quinolone resistance-determining region (QRDR) of type II topoisomerase genes in ciprofloxacin (CIP)-resistant clinical isolates and in vitro mutants of Streptococcus parauberis. The CIP-resistant clinical isolates had one base change responsible for a Ser-79${\rightarrow}$Thr in the QRDR of parC. However, the CIP-resistant in vitro mutants had an altered QRDR of parC (Ser-79${\rightarrow}$Ile) that differed from that of the isolates. None of the CIP-resistant S. parauberis clinical isolates or in vitro mutants exhibited amino acid changes in gyrA or gyrB. However, even though involvement in the increased resistance was not clear, an Arg-449${\rightarrow}$Ser mutation outside of the QRDR of parE was detected in CIP-resistant mutant 2P1. These results suggest that the topoisomerase IV gene, parC (and possibly parE, as well), is the primary ciprofloxacin target in S. parauberis. Additionally we established a high-resolution melting (HRM) assay capable of detecting the dominant mutation in four type II topoisomerase genes conferring ciprofloxacin resistance. These rapid and reliable assays may provide a convenient method of surveillance for genetic mutations conferring antibiotic resistance.

• Korean Journal of Fisheries and Aquatic Sciences
• /
• v.46 no.4
• /
• pp.445-453
• /
• 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 Microbiology and Biotechnology
• /
• v.20 no.2
• /
• pp.271-280
• /
• 2010

Vibrio alginolyticus, a Gram-negative marine bacterium, is one of the causative agents of fish vibriosis. Its virulence factors and pathogenesis mechanism are barely known, except for some extracellular products (ECPs) that are known to be regulated by quorum sensing system. Therefore, the present study used a microarray to analyze the transcription profiles of the wild-type V. alginolyticus and a deletion mutant of luxO, the pivotal regulator in Vibrio quorum sensing systems, which resulted in the identification of a putative virulence factor, MviN. Quantitative real-time reverse transcription PCR confirmed that the transcription of mviN was upregulated in the luxO mutant when compared with wild-type, and down regulated in a luxO-con complemented strain. Furthermore, Western blotting indicated that MviN was greatly induced during the late-exponential and stationary phases of growth, indicating that the expression of MviN was cell-density dependent and quorum sensing regulated in V. alginolyticus. Meanwhile, the mviN null mutant displayed a much slower growth rate than the wild type, signifying the essential role of MviN in V. alginolyticus. Western blotting also revealed that MviN was present as an extracellular protein in V. alginolyticus. When epithelioma papulosum cyprini (EPC) cells were treated with the ECPs of the mviN mutant, no cytotoxicity was observed, whereas EPC cells treated with the wild type exhibited pathological changes, which increased with the ECPs concentration and treatment time. Therefore, the results demonstrated that MviN is a LuxO-regulated ECPs component and involved in the pathogenicity of V. alginolyticus.

• Korean Journal of Fisheries and Aquatic Sciences
• /
• v.36 no.3
• /
• pp.283-289
• /
• 2003

The effect on kidney, gill, and hepatopancreas of juvenile olive flounder, Paralichthys olivaceus were investigated by histological method under limit concentration of effulent of PCBs for 60 days. The free surface of epithelial cell layer in the renal tubules of kidney showed a strong positive reaction in alcian blue during all exposure period. There were also observed swelling of hemocyte in glomerulus and macrophage. At 60 days after exposure, epithelium of the renal tubules was fused and some of organism $(20\%)$ showed damage of glomerulus and eosinophlic cell in epithelium of the renal tubules. The phenomena such as the activation and increase of the chloride cell, and swelling of hemocyte in the capillary of gill were observed during all exposure period. At 60 days after exposure, swelling of the gill filament and mucous cell appeared in gill and some of organism $(30\%)$ showed swelling of the gill lamellar. Swelling of hemocyte in the capillary of hepatopancreas was observed and the free surface of epithelial layer of the bile duct showed positive reaction in alcian blue during all exposure period. Degenerated zymogen in the pancreas and swelling of the hepatocyte were occurred at 60 days after exposure.

• Journal of Aquaculture
• /
• v.21 no.2
• /
• pp.107-110
• /
• 2008

This study was conducted to evaluate extruded pellet for the growth of grower Korean rockfish Sebastes schlegeli. Two replicate groups of 150 fish per each tank(initial mean weight 112 g) were fed one of four experimental extruded pellets for 8 months. Survival was 100% in all groups. Final mean weight, feed efficiency and protein efficiency ratio, feed intake and hepatosomatic index were not significantly different among all groups. Proximate compositions of the whole body and liver were not significantly different among all groups. It can be concluded that the dietary formulation used in four extruded pellets could be applied in the practical extruded pellet for grower Korean rockfish.

• Proceedings of the Fisheries Business Administration Society of Korea Conference
• /
• 2007.06a
• /
• pp.133-158
• /
• 2007

This study aims at analyzing the potential of leports-fishing for improving fishing household income. Leports-fishing is a composite concept which is combined with those of leisure, sports and fishing. Korean on-shore resources have also a composite characteristic. The characteristics of the east, west and south coastal waters are quite different in geography, biology and ecology. There is a array of leports-fishing development potentials of utilizing their characteristics. At present, angling forms a main activity of leports-fishing, but coastal seas would be an emerging space for the public. In order for them to be a ground of fun, enjoyment and festivals, there would be necessary to supply a wide range of activities including angling, scuba diving, fish barbecue, ecological experience, fishing experience, cruise, and so forth. As seen in the survey results, the participants have strong desire for fun and enjoyment through leports-fishing activities. The proportion of people participating in one or two times a year amounts to 40 percent. Most coastal places visited are close to medium/large cities and two-days leports-fishing/ tourism accounts for some 77 percent. However, it is shown that conflicts between leports-fishing participants and fishermen are not serious. The results of expenditure function estimation appear that the elasticity of per capita income is very high with 1.2660 and that there are negative relationships between leports-fishing expenditure and transportation/food/lodging costs. Assuming the economic growth rate of 4 percent, it is anticipated that Korean leports-fishing population will increase to 3.18 million in 2010 and 4.07 million in 2015. Korean leports-fishing market potential in 2015, which is calculated based on per capita expenditure on leports-fishing appeared to be 1,400 billion won$\sim$1,600 billion won. The contribution of such market potential is expected to be 62.3$\sim$74.2 percent(934.5 billion won$\sim$111.3 billion won) to the fishing households.

• Journal of Environmental Health Sciences
• /
• v.31 no.5 s.86
• /
• pp.411-414
• /
• 2005

Clean Natural is a new disinfectant of which main components are propolis and wood vinegar from Quercus mongolica. The mutagenicity of Clean Natural was studied by a micronucleus test in male ICR mice. The maximally tolerated dose (MTI) of Clean Natural was determined to >2.0 g/kg body weight. Therefore, the doses adopted for the micronucleus test was 2.0 g/kg as a high dose, 1.0 g/kg as a medium and 0.5 g/kg as a low of dose, respectively. Each of group was consisted of three doses of Clean Natural, positive control 2 mg/kg of mitomycin C and negative control 20 ml/kg of saline. A slide preparation was made at 24 hours following administration. No significant induction of micronuclei was observed in any of the three doses of Clean Natural orally administered. No cytotoxicity such as inhibition of hemopoiesis was observed in any group of test agent as the rate of polychromatic erythrocytes to total erythrocytes was over 40%. These results indicate that Clean Natural is not capable of inducing micronuclei in vivo mouse cells and thus has no genotoxicity in micronucleus test.

• Journal of Environmental Health Sciences
• /
• v.39 no.4
• /
• pp.376-382
• /
• 2013

Objectives: The objectives of this study were to identify the virucidal efficacy against the viral hemorrhagic septicemia virus (VHSV) of an aquatic disinfectant tablet composed of calcium hypochlorite. Methods: Virucidal efficacy was determined through the viability of VHSV contacted with the disinfectant in a viral stock cultured in a fathead minnow cell line. An aquatic disinfectant tablet and VHSV were reacted under distilled water (DW), hard water (HW) or organic matter suspension (OM) conditions. Results: Under DW and HW conditions, VHSV was inactivated with 24,000- and 2000-fold dilutions of the aquatic disinfectant tablet, respectively. With the investigation of the antiviral effect of the disinfectant under OM conditions, VHSV was inactivated with a 16,000-fold dilution of the aquatic disinfectant tablet. Conclusions: The results from this study showed that the aquatic disinfectant tablet was a highly effective disinfectant against VHSV. In the future, a controlled field trial is required to determine whether the use of an aquatic disinfectant tablet will be able to reduce VHSV in a cultured marine fish farm.

• The Journal of the Korea institute of electronic communication sciences
• /
• v.12 no.1
• /
• pp.85-92
• /
• 2017

Recently, electric propulsion systems are used for unmanned surface vehicle, fish finder boat, etc. Some of these propulsion systems can be constructed of two electric motors and propellers for advanced impellent force. In this case, the speed difference generated between two propellers, namely, the synchronous error has a bad influence on the energy efficiency and course error. In this study, a synchronous control system is designed to restrain synchronous error caused by disturbance and mismatched dynamic characteristics. The control system is composed of the reference model, pre-filters, speed controllers, and synchronous controllers. The reference model is used for calculating the decoupled synchronous error and control input for each propulsion system. The pre-filters and speed controllers are designed in order that the propulsion system may follow the reference signal without overshoot and input saturation. And the synchronous controllers are designed from the viewpoint of stable and quick synchronization through root locus mothed approach. Finally, the simulation results show that the designed control system is effective for the disturbance.

• Asian-Australasian Journal of Animal Sciences
• /
• v.15 no.4
• /
• pp.470-476
• /
• 2002

Random amplified polymorphic DNA (RAPD) analysis based on numerous polymorphic bands have been used to investigate genetic similarity and diversity among and within two cultured and wild populations represented by the species crucian carp (Carassius carassius). From RAPD analysis using five primers, a total of 442 polymorphic bands were obtained in the two populations and 273 were found to be specific to a wild population. 169 polymorphic bands were also produced in wild and cultured population. According to RAPD-based estimates, the average number of polymorphic bands in the wild population was approximately 1.5 times as diverse as that in cultured. The average number of polymorphic bands in each population was found to be different and was higher in the wild than in the cultured population. Comparison of banding patterns in the cultured and wild populations revealed substantial differences supporting a previous assessment that the populations may have been subjected to a long period of geographical isolation from each other. The values in wild population altered from 0.21 to 0.51 as calculated by bandsharing analysis. Also, the average level of bandsharing values was $0.40{\pm}0.05 $ in the wild population, compared to $0.69{\pm}0.08$ in the cultured. With reference to bandsharing values and banding patterns, the wild population was considerably more diverse than the cultured. Knowledge of the genetic diversity of crucian carp could help in formulating more effective strategies for managing this aquacultural fish species and also in evaluating the potential genetic effects induced by hatchery operations.