• Korean Journal of Fisheries and Aquatic Sciences
• /
• v.41 no.1
• /
• pp.20-25
• /
• 2008

The susceptibility of five different marine fish to iridovirus IVS-1 infection was analyzed and found a higher the cumulative mortality in the order of rock bream (Oplegnathus fasciatus), red sea bream (Pagrus major), sea perch (Lateolabrax sp.), rockfish (Sebastes schlegeli) and black porgy (Acanthopagrus schlegeli). However, the concentrations of virus in the infected spleens of these species did not differ significantly. To determine the release of iridovirus from infected fish into culturing seawater, rock bream were challenged with iridovirus IVS-1 and the concentration of virus in the water was analyzed using PCR. Over the 10 days of the analysis, the linear relationship between the number of dead fish and viral DNA concentration found in culturing seawater should be considered direct evidence of horizontal iridovirus transmission.

• Proceedings of the Microbiological Society of Korea Conference
• /
• 2005.05a
• /
• pp.28-32
• /
• 2005

Epifluorescence microscopy and direct viable counting methods have shown that only 0.01-0.1% of all the microbial cells from marine environments form colonies on standard agar plates. To culture novel marine microorganisms, high throughput culturing (HTC) techniques were developed to isolate cells in very low nutrient media. This approaches was designed to address microbial metabolic precesses that occur at natural substrate concentrations and cell densities, which are typically about three orders of magnitude less than in common laboratory media. Approximately 5000 cultures of pelagic marine bacteria were examined over the course of 3 years. Up to 14% of cells from coastal seawater were cultured using this method, a number that is 1400 to 140-fold higher than obtained by traditional microbiological culturing techniques. Among the cultured organisms are many unique phylogenetic lineages that have been named as new phyla (7), orders (2, 5, 12), families (3), and genera (1, 4, 6). Over 90% of the cells recovered by this method do not replicate in standard agar plating, the most common method of microbial cell cultivation.

• Korean Journal of Fisheries and Aquatic Sciences
• /
• v.46 no.1
• /
• pp.46-52
• /
• 2013

After an outbreak of viral disease in an aquafarm, release of virus (es) from infected fish into environmental seawater has been suspected. In the present study, we utilized a negatively charged membrane (HA type) as an efficient method for concentration and detection of fish pathogenic viruses, specifically, megalocytivirus and viral hemorrhagic septicemia virus (VHSV) present in field-collected seawater samples or inoculated into seawater artificially. Positively charged viruses adsorbed onto the negatively charged membrane and were eluted with 1 mM NaOH (pH 10.5) following rinsing with 0.5 mM $H_2SO_4$ (pH 3.0). Megalocytivirus and VHSV particles isolated using anegatively charged HA membrane from seawater inoculated with each virus at a concentration of 10 viral particles/mL were of sufficient quantity to show positive results in atwo-step PCR (or RT two-step PCR); however, despite it being negatively charged, a cellulose acetate (CA) membraneshowed negative results. In quantitative PCR, the detection limits of the HA membrane for megalocytivirus and VHSV in seawater were 1.20E+00 viral particles/mL and 1.22E+01 viralparticles/mL, respectively. The calculated mean recovery yields from 1 L seawater spiked with known concentrations of megalocytivirus and VHSV particles were 28.11% and 23.00%, respectively. The concentrate of a 1-L sample of culturing seawater from the aquatank of flounder suffering from VHSV showed clear positive results in PCR when isolated with an HA, but not a CA, membrane. Thus, viral isolation using an HA membrane is a practical and reliable method for detection of fish pathogenic viruses in seawater.

• Journal of Aquaculture
• /
• v.19 no.1
• /
• pp.14-18
• /
• 2006

The objective of this study was to evaluate food value and profitability of black porgy (Acanthopagrus schlegeli) cultured in freshwater. In fish flesh, muscular hardness of black porgy reared in freshwater $(9210{\pm}1215g/cm^2)$ was slightly lower than those of fish in seawater $(9987{\pm}6549g/cm^2)$, but there was no significant difference. Also, there was no difference between muscular strength of fish reared in freshwater and seawater. When the flesh qualities of black porgy reared in freshwater was compared with those of fish reared in seawater through the questionnaire, there were no significant differences between fish reared in freshwater and seawater in appearance, texture, taste and flavor. For 10 months of black porgy culture in fresh water, the gross profit in culturing from juvenile (5.5 g) to adult size (100g), and from adult to marketable size (400 g) were 24,000,000 won (30.0%) and 53,870,000 won (36.9%), respectively.

• ALGAE
• /
• v.34 no.2
• /
• pp.177-185
• /
• 2019

Ecklonia cava is popular in Korea as a marine functional materials. E. cava is generally collected and used on the coast of Jeju Island. However, the continuous use of collected natural E. cava may be limited because difficult to secure throughout the year and may be exposed to environmental pollution. Jeju magma seawater (MSW) was known to be significant advantages such as safety, cleanness, stability, and functional improvement. Attempts have been reported on application of MSW to the culturing of macro- and microalgae and showed improved results. Thus, the objective of the present study was to explore the anti-melanogenesis activity of brown seaweed E. cava (E. cava cultured with MSW [MSWE]) extract cultured in tanks with MSW of Jeju Island to evaluate the possibility of cosmeceutical industrial application. MSWE extract showed the higher polyphenolic and dieckol contents than natural E. cava (NE) extract. Anti-melanogenesis activity of MSWE extract and NE extract are tested and compared using tyrosinase and dihydroxyphenylalanine (DOPA) oxidation inhibition assay. MSWE extracts evidenced more effective tyrosinase and DOPA oxidation inhibition activity than that of the NE extracts and the commercial whitening agent, arbutin. MSWE extracts also markedly inhibited melanin synthesis and decreased the expression of melanogenesis-related protein in ${\alpha}$-melanocyte stimulating hormone-stimulated B16F10 melanoma cells without cytotoxicity. These results suggest that MSW cultivation process would be more effective in releasing bioactive compounds with whitening effect from seaweed such as E. cava at an industrial scale.

• The Journal of Fisheries Business Administration
• /
• v.44 no.3
• /
• pp.77-84
• /
• 2013

While some steps in laver aquaculture production can be controlled artificially to a certain extent, the culturing process is largely affected by natural factors, such as the characteristics of seawater, climatic and oceanographic conditions, etc. This study aims to find a direct relationship between climatic and oceanographic factors (water temperature, air temperature, salinity, rainfall, sunshine duration and wind speed) and laver aquaculture production in Wando region, the biggest aquaculture production area of laver, located in the southwest coast of Korea using a multiple regression analysis. Despite the small sample size of a dependent variable, the goodness of model fit appeared acceptable. In addition, the R-squared value was 0.951, which means that the variables were very explanatory. Model results indicated that duration of sunshine, temperature, and rainfall during the farming period from the end of September to the end of April would be important factors affecting significantly to the laver aquaculture production.

• Journal of Microbiology and Biotechnology
• /
• v.11 no.2
• /
• pp.302-309
• /
• 2001

Colony blot hybridization using a VVHP DNA probe derived from the sequence of the hemolysin gene, vvhA, was specific in identifying all V. vulnificus strains, thereby, eliminating the need for any additional phenotypic identification. The colony blot hybridization procedure revealed a sensitivity and broad applicability sufficient for the direct enumeration of V. vulnificus in various natural samples, without the use of enrichment or culturing on selective medis. V. vulnificus was detected in all natural samples collected during August and May at concentrations ranging from $2.1{\times}10^1\;to\;4.0{\times}10^3$ organisms per ml. However, during November and February, when the mean temperatures of the seawater were $12^{\circ}C$ and $5^{\circ}C$, respectively, V. vulnificus was not detected in any natural samples.

• Journal of Aquaculture
• /
• v.10 no.1
• /
• pp.1-7
• /
• 1997

In the southern sea of Korea, the culturing Rock bream, Oplegnathus fasciatus, ranging from 16.3 to 20.1cm in body length were sampled to examine how serious parasitic infection is. As a result, they were infected with 10 to 31 individuals of Monogenea, Benedenia sp. The parasitic sites of fish body was trunk (81.8%), caudal peduncle (16.5%) and the other portion (1.6%), and where ulceration and bleeding were observed with a large amount of muscus. When the treatment with formalin and freshwater were performed to get rid of the parasite, they were exterminated after 8 and 20 minutes in 100% and 70% freshwater, respectively and were killed after 10, 15 and 20 mimutes in the seawater added with formalin to be 250 ppm, 200 ppm and 150 ppm, 200 ppm and 150 ppm, respectively. During the treatment for parasite extermination, the fish showing a serious illness were dead in the 100% freshwater, whereas toxicity caused by formalin treatment was not detected in this study. The former is probably due to failure in the osmotic regulation of Rock bream.

• Journal of Fisheries and Marine Sciences Education
• /
• v.27 no.4
• /
• pp.1184-1193
• /
• 2015

Monitoring for megalocytivirus infection was conducted for ten months from March to December in 2013 in 15 aquatic farms culturing, red sea bream, rock bream, rock fish and black sea bream around Tongyoung coastal area in Korea, to assess spatial and temporal variability of detection prevalence, and to explore possible links with seawater temperature. In nested-PCR targeted major capsid protein (MCP) gene, asymptomatic megalocytivirus infection was detected in the externally healthy farmed fish with a significant prevalence in range from 0 to 58.3% for ten months. Higher prevalence of megalocytivirus (46.7% - 57.1%) was observed in high water temperature season from September to November than that in other months with lower prevalence of 0.0% to 20.0%. Even though an acute infection of megalocytivirus was occurred in rock bream (positive in the first PCR) with high mortality in one of fifteen farms, there was no expansion or transmission of the disease to the rock fish and red sea bream culturing in net cage just proximal to the rock bream cage in which disease outbreaked. Nucleotide sequence analysis of the cloned MCP gene isolated asymptomatically infected rock fish revealed that the megalocytivirus in this study was clustered together with the rock bream iridovirus (RBIV) under the subgroup II of the genus megalocytivirus (Iridoviridae), which is known to be the major megalocytivirus strain in Korea. The typical histopathological signs were not found in the spleen of rock fish asymptomatically infected by megalocytivirus. Experimental infection of rock bream with the spleen homogenate of the rock fish infected asymptomatically did not induce any mortality unlike the homogenate of infected rock bream with hih mortlity. However, these results may suggest that the asymptomatic infection of megalocytivirus in other fish species can be a potential risk threatening aquaculture industries as a transmission factor of megalocytivirus to susceptible fish species, especially rock bream.

• ALGAE
• /
• v.25 no.1
• /
• pp.37-44
• /
• 2010

A tide-simulating apparatus was developed for culturing marine macroalgae. The objective of this study was to introduce a novel tide-simulating apparatus that can simulate a diurnal or semi-diurnal tidal cycle in the laboratory. In this apparatus, the seaweeds are move up and down and the water level remains the same during the simulated tidal cycle. The apparatus consists of 18 cylindrical culture tanks (3 blocks $\times$ 6 culture tanks) with 12 cm diameter and 24.5 cm long containing up to 2.5 L of seawater. There is a horizontal plate which covered all 18 culture tanks, and it is raised and lowered by a programmable motor that can regulate exposure time. In one application, seaweeds are attached to braided twine hung on Plexiglas air-tubing. The air-tubing is attached to a lid that is set on a horizontal plate. This apparatus is made of colorless Plexiglas to maximize light transmittance. This apparatus is easily disassembled and transportable to any indoor laboratory, wet laboratory, greenhouse, etc. This apparatus also offers considerable flexibility in terms of design. The size of culture tank can be redesigned by either increasing the height of cylinder or/and using a different diameter of cylindrical Plexiglas, therefore, larger/taller thalli can be cultivated. Growth rates of three eulittoral Porphyra species from different tidal elevations have been compared using this device.