• Journal of fish pathology
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• v.32 no.1
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• pp.21-28
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• 2019

It has been reported that various anti-oxidant substances stimulate non-specific immune responses in fishes. In this study it was examined whether N-acetylcysteine (NAC), a precusor for anti-oxidant glutathione (GSH) synthesis, can modulate non-specific immune function in Far Eastern catfish Silurus asotus. Immune functions were assessed using the respiratory burst activity monitored by chemiluminescence (CL) responses in isolated leucocyte. NAC stimulated CL responses with doses of 10 or 100 mg/kg, but not with 1 mg/kg after 48 hr injection. It was observed with 10 mg/kg NAC that CL activity continued to elevate from 24 hr through 96 hr post-dosing, and returned to the near preinjection level by 10 days. To understand whether NAC can also activate CL activity in vitro, NAC was directly added to isolated catfish leucocytes. It was observed, however, that NAC can not stimulate CL at reasonable concentration ranges in vitro. As NAC is a precursor for the strong anti-oxidant glutathione (GSH), a putative immune stimulator, it was assessed whether GSH can also stimulate CL responses. Observed results show that GSH activated CL both in vivo and in vitro. The data obtained collectively support the proposition that NAC indirectly stimulates non-specific immune functions in catfish by enhancing GSH biosynthesis, but not by direct action of NAC. Such effects may have beneficial significance in aquaculture for practical utilization.

• Journal of Fisheries and Marine Sciences Education
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• v.27 no.5
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• pp.1364-1368
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• 2015

This study was performed to evaluate mineral contents of catfish Silurus asotus. As a result of mineral content, the mean content of the macro mineral was (in descending order): K (310.36-412.66 mg/100 g), P (186.42-223.02 mg/100 g), Na (35.32-57.87 mg/100 g), Mg (22.88-31.87 mg/100 g), Ca (9.05-13.07 mg/100 g). In comparison, the mean content of the micro mineral was (in descending order): Fe (0.26-0.95 mg/100 g), Zn (0.26-1.02 mg/100 g), Cu (ND-0.08 mg/100 g), Mn (0.01-0.03 mg/100 g). A proportion of mineral intakes with the dietary reference intakes for Koreans (KDRIs) set by the Korean Nutrition Society. Nutrient uptake proportion of mineral intakes was (in descending order): P (62.16%), K (20.71%), Mg (16.82%), Fe (13.02%), Zn (11.38%) Cu (10.94%), Na (6.59%), Ca (3.09%), Mn (0.96%). The mineral content was compared with the major protein food sources according to the Korea Health Statistics (2013) such as polished rice, pork, chicken, beef, eggs and milk. The calcium content contains; lower level of milk and eggs, chicken whereas higher levels of rice, pork and beef. Catfish has less iron content than major protein food source. Phosphorus and potassium contain higher level of major protein food sources.

• Korean Journal of Ichthyology
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• v.11 no.2
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• pp.126-133
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• 1999

Ultrastructure of the zona radiata and the micropyle of ripe eggs in the rainbow trout (Oncorhynchus mykiss), catfish (Silurus asotus) and loach (Misgurnus anguillicaudatus) were examined by light, scanning and transmission microscopes. The egg micropyle of rainbow trout and catfish consists of a funnel-shaped vestibule and a tapered canal transversing the zona radiata. The micropyle of rainbow trout and catfish showed the similar structure with flat pit and long canal. The micropylar wall showed the clockwise spiral structure in rainbow trout. The micropyle of the loach showed the type with a hollow pit leading into a short canal and the micropylar wall showed the counterclockwise spiral structure. There are numerous and various size pores at the surface area around the opening in every experimented fish. Interconnecting ridges were observed in the unfertilized eggs of every fish.

• Development and Reproduction
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• v.21 no.4
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• pp.399-406
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• 2017

This study was conducted to investigate egg development and larvae morphological development of catfish and to provide basic data to clarify the genetic relationship with Siluriformes fish. The mother fish that was used in this study was caught in the stream of Nakdong River in Uiseong-gun, Gyeongbuk. The temperature range of the breeding was $23.0-25.0^{\circ}C$ (mean $24.0{\pm}1.0^{\circ}C$) and egg size was 1.62-1.70 mm (mean $1.66{\pm}0.05$, n=30). Eggs of catfish began hatching at 54 hours and 40 minutes after fertilization. Immediately after hatching, the total length of larvae was 3.60-3.65 mm (mean $3.62{\pm}0.03$, n=5) and had an egg yolk without swimming ability. On the third day after hatching, the larvae at the medium stage was 8.00-8.65 mm (mean $8.32{\pm}0.45$) in total length, and two pairs of whiskers formed around the mouth were elongated. On the 12th day after hatching, the larvae at the juvenile stage was 16.5-17.0 mm (mean $16.7{\pm}0.35$) in total length, and the stem of each fin was in the range, and the juvenile at this period was morphologically similar to the mother fish.

• Journal of Life Science
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• v.26 no.3
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• pp.296-301
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• 2016

An antibacterial peptide from skin extract of the catfish Silurus asotus was purified and characterized. The acidified skin extract was put through a Sep-Pak C18 solid phase extraction cartridge using a stepwise gradient and divided into flow-through (F.T.), 10% methanol-elute (RM10), 60% methanolelute (RM60), and 100% methanol-elute (RM100) fractions. RM10, RM60, and RM 100 showed antimicrobial activity against Escherichia coli D31. On the other hand, the F.T. fraction did not show antimicrobial activity. Among the various fractions, RM 60 had the highest activity. RM 60 was partially purified on a cation exchange column (CM52) by a stepwise gradient. The ammonium acetate (pH 5.15) 0.02 M – 0.8 M fraction showed antimicrobial activity. Then an antimicrobial peptide was purified using a 0.6M fraction with strong antibacterial activity through a series of five C18 reversed-phase HPLC columns. For the characterization of the purified peptide, the molecular weight and amino acid sequence were analyzed by MALDI-TOF MS and Edman degradation. The molecular weight of this peptide was about 4182.1 [M+H]⁺. The amino acid sequence of this peptide was partially determined as follows: PALXXKARREAKVKF. These findings suggest that this peptide plays a significant role in the innate defense system of catfish skin.

• Korean Journal of Ichthyology
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• v.17 no.1
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• pp.36-42
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• 2005

Histological observations on the barbels of catfish (Siluridae) in Korea are reported. The mandibular barbel of Far Eastern catfish, Silurus asotus, has epidermis and dermis surrounding an axial rod of cartilage. The stratified epidermis embodies mucous cells, club cells, and taste buds. The mucous cells, which are thin rims of basophilic cytoplasm, and the taste buds, which are basophilic, are located at the surface and the distal portion of the epidermis, respectively. The basement membrane lies between the epidermis and dermis except in places of dermal papillae. The dermis is made up of loose connective tissue fibers enclosing nerve bundles and blood vessels. The central region of cartilage is innermost and enclosed within muscle layers. The mandibular barbel of slender catfish, S. microdorsalis, has an identical structure to those of the Far Eastern catfish however, the percentage thickness of epidermis in the upper and lower parts of the barbel and the number of taste buds in the upper and middle parts of the barbel are different from those of Far Eastern catfish. This study shows that the mandibular barbels in Far Eastern catfish and slender catfish are of a stiff and flexible type.

• Korean Journal of Ichthyology
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• v.29 no.1
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• pp.22-31
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• 2017

To find out the stress response and wound healing of surgical incisions, we analyzed the change of stress hormone and the healing process in far eastern catfish, Silurus asotus. The survival rate of the clove oil (1,000 ppm) anesthesia group after surgery was about 90% in 3~42 days, while no anesthesia group showed about 74%. Thus, the survival rate after anesthesia group was higher than that of the no anesthesia group. The plasma cortisol concentration of the clove oil anesthesia group was higher than that of the no anesthesia group (P<0.05). In addition, the plasma glucose concentration of clove oil anesthesia group was higher than that of the no anesthesia group (P<0.05). The plasma lactic acid concentration of clove oil anesthetized group was higher than that of the not anesthetized group (P<0.05). On the 14 days and 28 days after surgery, there were still stitching fiber of suture and swimming behavior was not active. On the 35 days after surgery, trace of the suture has almost disappeared on the outside of the fish. Finally, 42 days after surgery, stitching fiber was not visible, and the sutured wounds were distinctly recovered. The results of this study showed that the anesthesia group showed higher survival rate and received less postoperative stress than that of the no anesthesia group. Surgical wound healing in the catfish of this study was shown to be successful when using anesthetics.

• Development and Reproduction
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• v.21 no.3
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• pp.275-286
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• 2017

The purpose of this study is to investigate the differences fatty acids and hormonal parameters in the spawning and non-spawning season between the diploid and induced triploid Far Eastern catfish, Silurus asotus. The measured triploids were produced by cold shock for 50 min at $4^{\circ}C$ in May 2014, the spawning season of diploid was in May, and the non-spawning season was designated in January. Estradiol and testosterone and gonadosomatic index of diploid were higher than those of induced triploid in spawning season (P<0.05), and those of diploid in spawning season were higher than non-spawning season. On the other hand, thyroid stimulating hormone and thyroxine of induced triploid were higher than those of diploid in spawning season (P<0.05). Erythrocyte count of diploid was higher than that of induced triploid in spawning season and non-spawning seasons. Mean corpuscular volume and mean corpuscular hemoglobin of induced triploid were higher than those of diploid in both seasons (P<0.05). Percentages of total saturated fatty acids and n-3 polyunsaturated fatty acids of induced triploid were higher than those of diploid in spawning season, but those of diploid were higher in non-spawning season (P<0.05). Percentages of total mono unsaturated fatty acids and total n-6 polyunsaturated fatty acids of diploid were higher than those of induced triploids in spawning season, while those of induced triploid in non-spawning season were higher (P<0.05). Therefore, induced triploids in the spawning season tend to concentrate on growth and lipid-synthesization, whereas, diploids concentrate on reproduction and gonadal maturation rather than on growth. In non-spawning season, growth and lipid-synthesization were not significantly different between diploid and induced triploid.

• Korean Journal of Environmental Agriculture
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• v.42 no.4
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• pp.408-417
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• 2023

This study aimed to investigate the effects of an aquaponics system utilizing catfish recirculating water on the growth and water quality in lettuce and chicory cultivation. After 60 d of catfish cultivation in the BFT-AP, the survival rate was 96.0% and average weight gain was 178.5 g. The WGR grew by 241.4% and the SGR was 3.0%. A comparison between lettuce and chicory cultivation using BFT-AP and hydroponics revealed significant increases in shoot height, leaf count per week, and biomass of the cultivated lettuce and chicory. The SPAD values also increased significantly by 15.4-43.3%. Water quality analysis of the BFT-AP systems and crop cultivation beds showed significant differences, except for K and Na. The average NO₃^- concentration in the sediment pond was significantly higher at 45.3±1.0. Comparison of water temperature, pH, EC, DO, and ORP in the BFT-AP system and crop cultivation beds revealed similar monthly water temperatures from July to September. The pH in the catfish culture pond was 0.3-1.2 lower than that in the crop cultivation beds, and the EC was approximately 0.01- 0.03 dS/m lower in the catfish culture pond than the crop cultivation beds. The monthly average ORP in the catfish culture bed steadily increased to 479.9 mV in October. Bacillus velezensis (AFB2-2) and Chlorella fusca (CF) were applied to the biological activation bed; the population density of CF showed a continuous increase, whereas that of AFB2-2 decreased after 15 d and gradually increased thereafter. Thus, the application of the recirculating aquaponics cultivation technology with catfish (BFT) enhances catfish cultivation and promotes the growth of lettuce and chicory. Therefore, it is considered suitable for the environment-friendly cultivation of lettuce and chicory.

• Ecology and Resilient Infrastructure
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• v.5 no.2
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• pp.105-109
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• 2018

The main objective of this investigation was to examine oxygen consumption and ammonia excretion within cultured catfish, Silurus asotus ($22.9{\pm}0.9cm$, $100.7{\pm}11.7g$ n = 30) by noise and vibration stress in aquaculture farm. The vibration of 48, 58 and 68 dB (V) and noise of $77.6{\pm}1.8dB$ (A) from an electric vibrator was turned on for 15 minutes during each hour each day(0800-1800) for 11 days experimental period. The oxygen consumption (OC) of S. asotus the beginning of the experiment (0 day) in 58 dB group after 1, 5, 9 and 11 days was decreased 21.8, 30.2, 36.0 and 53.2%, respectively. In 68 group after 1, 7 and 11 days was decreased 22.7, 35.1 and 57.7%, respectively. The OC decreased exponentially and the relationship between them was expressed as OC = 0.374D + 90.762 ($r^2=0.048$) at 48 dB, OC = -3.581D + 89.520 ($r^2=0.831$) at 58 dB and OC = -4.109D + 90.907 ($r^2=0.884$) at 68 dB. Ammonia excretion (AE) of the beginning of the experiment in 48, 58 and 68 groups after 1 day was increased by 34.8, 51.8 and 63.2%, respectively, but it was decreased significantly from 3 to 11 days. The AE increased exponentially and the relationship between them was expressed as AE = -1.646D + 115.915 ($r^2=0.265$) at 48 dB, AE = -8.230D + 122.132 ($r^2=0.750$) at 58 dB and AE = -7.086D + 123.690 ($r^2=0.614$) at 68 dB.