Jae-Kwon Cho

Biochemical characteristics of four marine fish skins in Korea

In this study, we investigated the biochemical characteristics of the fish skins of four industrial species: olive flounder (Paralichthys olivaceus), black rockfish (Sebastes schlegeli), sea bass (Lateolabrax maculatus) and red sea bream (Pagrus major). There is high domestic demand in Korea for farming of these fish for human consumption. Crude protein contents in the skin of these fish ranged from 73% to 94% by dry weight; this was in part due to a high content of the structural protein, collagen. Among the four species, olive flounder had the thickest dermal and epidermal layers in the dorsal skin. This species was also associated with the highest extraction ratio of acid-soluble collagen. We also examined whether fish skin could be a cost-effective alternative to current fish meal sources. Our analysis indicates that, when supplemented with additional fish oils and essential amino acids, fish skin is a viable alternative for fish meal formulations.

Egg Development and Morphology of Larva and Juvenile of the Oryzias latipes

In order to monitor the developmental features of embryos, larvae, and juveniles of Oryzias latipes (Temminck and Schlegel), Oryzias latipes was caught in river of Shinduck-dong, Yeosu-si, Jeollanam-do, on May 2011, and experiments were carried out in Ichthyology laboratory at Chonnam National University. The blastodisc step was the first level for natural spawning. The optic vesicle, Kupffers vesicle, myotome began to appear 75 hours 57 minutes later. After blastodisc development, the pectoral fins were made at 143 hours 37 minutes and the tail was separated started at the same time. Hatching was observed at 167 hours 27 minutes after blastodisc. The total length of the hatched larvae was 4.95~5.10 mm (mean, 5.01 mm), the mouth and anus were opened. Larvae used yolk completely after 3 days after hatching. The total length larvae was 5.45~5.56 mm (mean, 5.52 mm) after 8 days after hatching, and appeared the stems for tail. The stems pectoral, anal fin were showed after 14 days and the stems dorsal, ventral fin were appeared after 19 days. For 35 days after hatching, the total length of larvae 13.95~15.30 mm (mean, 14.64 mm), and at this time, fins and body were transferred like the adult Oryzias latipes.

Complete Genome Sequence of Nervous Necrosis Virus Isolated from Sevenband Grouper (Epinephelus septemfasciatus) in South Korea

ABSTRACT The draft genome sequence of the nervous necrosis virus (NNV) SGYeosu08, isolated from sevenband grouper (Epinephelus septemfasciatus) in Yeosu, South Korea, was cloned and analyzed. The full-length RNA1 was a 3,103-nucleotide-encoding region of RNA-dependent RNA polymerase, and the RNA2 encoding a coat protein was 1,433 nucleotides in length. This genome sequence might be useful in the development of an accurate diagnostic tool.

Establishment and Characterization of the Epithelioma Papulosum Cyprini (EPC) Cell Line Persistently Infected with Infectious Pancreatic Necrosis Virus (IPNV), an Aquabirnavirus

Infectious pancreatic necrosis virus (IPNV), a type species of aquabirnaviruses in the family Birnaviridae, is an etiological agent of infectious pancreatic necrosis and has been isolated from epizootics of cultured salmonids. In the present study, an epithelioma papulosum cyprini (EPC) cell line persistently infected with IPNV (PI-EPC) was experimentally established by subculturing EPC cells surviving IPNV infection, and was characterized. PI-EPC cells were morphologically indistinguishable from EPC, but continued to grow and yield IPNV. PI-EPC cells showed no cytopathic effect due to IPNV inoculation, and susceptibility of PI-EPC cells against heterologous viruses was not different from that of EPC cells. Only one cell of 103.5 PI-EPC cells produced IPNV at approximately 100.5 50% tissue culture infectious dose (TCID50)/cell/day, which was approximately 1,000 times lower than that of normal EPC cells. PI-EPC cells that did not yield IPNV (N-PI-EPC) were screened. The IPNV genome was detected from both PI-EPC and N-PI-EPC cells, and the IPNV VP2 structural protein was detected from both cell lines, but no other IPNV proteins were observed by Western blot analysis with anti-IPNV serum. Thus, multiplication of IPNV in PI-EPC cells was regulated by some host cell factors, except interferon.

Early Life History of the Sevenband Grouper, Epinephelus septemfasciatus from Korea

This study is conducted to monitor the morphological developmental features of the egg development, larvae and juvenile of Epinephelus septemfasciatus, the fertilized eggs were gotton using artificial insemination. Matured parents are collected from marine caged fish farms in Geomun-ri, Samsan-myeon, Yeosu-si, Jeollanamdo Korea in June 2012. The fertilized eggs were pelagic eggs containing one oil globule, and measured 0.81~0.89 mm (0.85±0.04 mm, n=50) in diameter. In regard to rearing environment, the water temperature is 21.0~23.0°C and the salinity is 32.0~33.2‰. Hatching was observed from 48 hours after fertilization, the mouth and anus of prelarvae was not opened but had egg yolk at newly hatched. 4 days after hatching, the mouth and anus of postlarvae was opened and began to eat Rotifer and was measured 2.40~2.49 mm (2.45±0.03 mm n=10) in total length. 12 days after hatching, postlarvae was measured 3.77~4.67 mm (4.27±0.33 mm) in total length, its the second pole tide of dorsal fin and the first pole tide of pelvic fin was extended longitudinally. 71 days after hatching, juvenile was measured 40.5~45.4 mm (42.6±2.04 mm) in total length. Seven bands were observed in body, and pole tides of dorsal and pelvic fins were shortened.

Ovulation Induction Effect of Sevenband Grouper, Epinephelus septemfasciatus by Treating Hormones

Abstract This study aims to investigate how ovulation induction of sevenband grouper, Epinephelus septemfasciatus varies when treated with different hormonal substances such as ovaprim, pimozide, LHRHa, and HCG. As for LHRHa, we injected it in different concentrations: 50 ㎍/kg, 100 ㎍/kg, 150 ㎍/kg, and 200 ㎍/kg. All hormonal substances including LHRHa were injected into back muscles. As a result, ovulation occurred in all sample groups. The sample group injected with HCG released the largest amount of eggs, and the dimeter of eggs and oil globules were also significantly bigger than those of others. Fertilization rate, embryonic survival rate, and hatching rate were the highest in a LHRHa (100 ㎍/kg) +pimozide (1,000 ㎍/kg) group and buoyant rate in a LHRHa group. Ovulation rate was 100% when LHRHa was injected in different concentrations. The largest amount of eggs was released in 200 ㎍/kg. The diameter of eggs and oil globules were the biggest in 200 ㎍/kg and the smallest in 50 ㎍/kg. Fertilization rate showed no significant difference through all different levels of concentration: 94.6-95.3%. Buoyant rate was the highest in 100 ㎍/kg and embryonic survival rate and hatching rate in 150 ㎍/kg. Based on these experimental results, we concluded that LHRHa in 100 ㎍/kg is the most efficient for the ovulation induction of sevenband grouper.Key words : Sevenband grouper, Ovulation induction, Ovaprim, LHRHa, Pimozide, HCGCorresponding author : 061-690-8977, hwgang@korea.kr 2015 (RP-2015-AQ-034).

Gonadal Development, Spawning and Plasma Sex Steroid Levels of the Indoor Cultured Grunt, Hapalogenys nitens

The gonadosomatic index (GSI), gonadal development and changes in hormones in plasma level of the indoor cultured grunt (Hapalogenys nitens) were investigated by histological study from August 2011 to October 2012. The GSI showed similar trends with gonad developmental stages during the culture periods. Changes in plasma level of estradiol-17β of female H. nitens reached the highest value before the spawning period, and seasonal changes in plasma level of estradiol-17β were similar in trends of oocyte developments and GSI changes. Testosterone levels of male H. nitens reached the highest value before and after the spent stage. Ovarian developmental stages of H. nitens could be classified into early growing stage, late growing stage, mature stage, ripe and spawning stage, recovery and resting stage. The testicular developmental stages could be divided into growing stage, mature stage, ripe and spent stage, and recovery and resting stage.

Nutritional characteristics of black rockfish (Sebastes schlegeli) fed a diet of fish skin.

This study investigated the effects of diets substituted with different levels (0, 5, 10, and 20%) of flounder skin meal (FSM) on the nutritional composition of black rockfish Sebastes schlegeli. Fish (10.05 ± 0.44 g) were fed to apparent satiation twice daily for 8 weeks. Adding FSM decreased crude lipid levels and increased crude protein and ash. The abundant fatty acids in the FSM-added group were C16:0, C18:1-cis (n9), and C22:6n-3. The major amino acids in the samples were glutamic acid, aspartic acid, glycine, leucine, alanine, lysine, and arginine. The abundant free amino acids in the FSM-added group were taurine, glutamic acid, alanine, leucine, and arginine. Six free sugars were found in all groups. Glucose was predominant, followed by mannose, rhamnose, fucose, fructose, and ribose. Among the three organic acids in the whole body of black rockfish, lactic acid was predominant, followed by citric acid and oxalic acid. Total organic acid content in the control was significantly higher than those of FSM substitution groups.

Psoraleae semen Extract Inhibits Angiogenesis and Adipogenesis

Ethanol extracts of Psoraleae semen (PSE) are used in Korean folk medicine for tuberculostasis, nycturia, sarcoma, inflammation, and cancer. We investigated the utility of P. semen extract for the suppression of angiogenesis and adipogenesis. Eighteen natural products were screened using anti-angiogenesis experiments, and one candidate product was identified. Psoraleae semen provided dosedependent inhibition of angiogenesis, adipogenesis, and cell adhesion in vitro and weight loss in mice in vivo. The anti-angiogenenic efficacy of PSE was superior to that of epigallocatechin gallate (EGCG) obtained from green tea leaves. The expression of angiogenesis and adipogenesisrelated signal molecules was reduced by increasing the doses of PSE. A diet supplemented with PSE provided more effective weight loss in LB mice than did orlistat, a representative synthetic diet drug, which also caused hairloss in LB mice. P. semen may be a useful antiadipogenic compound if these in vitro results are replicated under in vivo conditions.