• Parasites, Hosts and Diseases
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• v.45 no.2 s.142
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• pp.149-152
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• 2007

A cohort was established for evaluation of cancer risk factors in Sancheong-gun, Gyeongsangnam-do, Korea. As one of the cohort studies, stools of 947 residents (403 males and 544 females, age range: 29-86 years) were screened for Clonorchis sinensis eggs using both Kato-Katz method and formalin-ether sedimentation technique. The overall egg positive rate of C. sinensis was 37.7% and individual EPG (eggs per gram of feces) counts ranged from 24 to 28,800. Eight egg positive residents voluntarily joined a process of collection of the passed worms after praziquantel treatment. A total of 158 worms were recovered from 5 of the 8 treated persons, ranged from 3 to 108 in each individual. The worms were $15-20 mm{\times}2-3 mm$ in size, and showed brown-pigmented, red, or white body colors. This is the first collection record of C. sinensis adult worms from humans through anthelmintic treatment and purgation. The adult worms of C. sinensis may be paralyzed by praziquantel and then discharged passively through bile flow in the bile duct and by peristaltic movement of the bowel.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.30 no.4
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• pp.627-633
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• 1997

Gonad structure, germ cell development and reproductive cycle of the smallmouth scorpionfish, Scorpaena miostoma were investigated based on histological method. Samples were collected monthly in the vicinity of Suyoung Bay, Pusan, Korea from November 1995 to October 1996. The testis is seminiferous tubule type in internal structure. Seminiferous tubule consists of numerous testicular cysts which contain numerous germ cells in same developmental stage. The ovary consists of several ovarian lamellae originated from ovarian outer membrane. Oogonia originated from the inner surface of the ovarian lamella protrude to the ovarian cavity in oocyte stage, and they are suspended by the egg stalk. Biological minimum size of female and male were 12.5cm in total length. Gonadosomatic index (GSI) of female (3.81) and male (0.23) were the highest in October. Reproductive cycle was classified into the following successive stages: in female, growing stage $(May\~August)$, maturation stage $(September\~October)$, ripe and spawning stage $(November\~December)$, recovery and resting stage $(January\~April)$, and in male, growing stage $(June\~August)$, maturation stage $(September\~October)$, ripe and spent stage $(November\~January)$ and recovery and resting stage $(February\~May)$.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.46 no.2
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• pp.119-128
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• 2013

A protease inhibitor was fractionated from fish eggs using methods based on protein solubility. Fractionation efficiency was evaluated with regard to percent recovery and total inhibitory activity (U). The fractionation of protease inhibitor (PI) from egg extracts of skipjack tuna (ST, Katsuwonus pelamis), yellowfin tuna (YT, Thunnus albacores), and Alaska pollock (AP, Theragra chalcogramma) was performed by precipitation with cold acetone or ammonium sulfate (AS). Fractions exhibiting the strongest inhibitory activity contained 20-40% (v/v) cold acetone or 40-60% saturated AS fractions. AS fractionation was more effective in isolating PI than was precipitation with acetone. The total inhibitory activity and percent recovery of fraction obtained with AS 40-60% toward trypsin and $N{\alpha}$-benzoyl-L-arginine-p-nitroanilide (BAPNA) were 4,976 U and 24.2% for ST, 3,331 U and 38.1% for YT, and 4,750 U and 43.8% for AP, respectively. In comparisons against six commercial proteases, 40-80% AS fractions, made by combining the 40-60% and 60-80% AS fractions from fish egg extract, exhibited the strongest inhibition of trypsin when using a casein substrate. These results suggest that fish eggs act as serine protease inhibitors and may be useful for protease inhibition in foodstuffs.

• Journal of Aquaculture
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• v.17 no.1
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• pp.30-38
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• 2004

To estimate the spawning period the annual change of gonadosomatic index (GSI) were examined from January 2000 to December 2001. Fecundity, spawning frequency and egg diameter were measured by ocular observation. Germ cell differentiation during gametogenesis, the reproductive cycle and the first sexual maturity of greenling Hexagrammos otakii were observed under light microscopy from January to December, 2000. GSI began to increase in August and reached the maximum in November when ovary was getting mature. The reproductive cycle of H. otakii can be divided into five successive stages in females: early growing stage (July), late growing stage (July to August), mature stage (September to October), ripe and spent stage (September to December), and recovery and resting stage (December to June). Males showed four successive stages : growing (June to August), mature (August to October), ripe and spent (September to December), and recovery and resting stage (December to May). According to the frequency distributions of egg diameter in spawning season, H. otakii could be one of polycyclic species spawning 2 times or more during one spawning season. Number of total eggs and mature eggs in the absolute fecundity were related to the standard length and body weight, respectively. Number of total eggs and mature eggs in relative fecundity were also proportional to the standard length, but rather these numbers decreased with body weight. Percentages of first sexual maturity of females and males in greenling were over 50% from 19.1 to 21.1cm in length, and 100% for fish over 25.1cm in length. Therefore, both sexes are ready to reproduce after one year old.

• Parasites, Hosts and Diseases
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• v.23 no.1
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• pp.24-32
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• 1985

The worm development and egg laying pattern of Echinostoma hortense (Trematoda; Echinosto-matidae) were studied in albino rats and the brief clinical course was observed in human volunteers. A total of 21 rats were infected with 20~69 metacercariae each and two humans were with 7 and 27 metacercariae, which were collected from the loaches. For recovery of worms, the rats were sacrificed at irregular intervals from the 6th to 150th day after infection and the human volunteers were treated with praziquantel and purged with magnesium salt on the 26~27th day. The stools of the rats and humans were examined for the eggs. The results were as follows: 1. The worm recovery rate from the rats was not affected by the increase of infection time but varied individually; 9.1~50.0% (31.1 % in average). From humans, 14.3% and 37.0% (32.4% in average) of challenged were recovered. 2. In the rats, it was revealed that the worms rapidly grew for the first 14 days to become 7.59mm in average length and 1.17mm in average width but the growth became much slower thereafter until the 150th day; 7.95mm in length on the 21 th day, 9.04mm on the 28th day, 10.21mm on the 49th day and 12. 62mm on the 150th day. During the early stage of infection, the growth of genital organs (male or female) was expressed as sigmoid curves whereas non-genital organs (such as suckers) was simply as straight lines. 3. The prepatent period of this fluke was 10~12 days in the rats and 16~17 days in men. After the start of oviposition, the egg production by the worms remarkably increased, reached maximum on the 32~33th day, followed by decrease thereafter. The maximum value of E.P.G./worm was 390. 4. The major subjective symptoms in human volunteers were abdominal pain and diarrhea during the early stage of infection. The results show that human is as susceptible as the rats to E. hortense infection and the amount of egg production in the rats is greatly affected by the age of worms.

• Korean Journal of Poultry Science
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• v.35 no.4
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• pp.391-398
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• 2009

The objective of the present study was to compare of the effects of four molting methods on performance of laying hens. In total, 120 White Leghorn layers (62 weeks of age) were used. The four molting methods consisted of 10 days of feeding and the first 3 days of water withdrawal (FW1, 2) followed by ad libitum access to a layer diet 1 and 2 from day 11; 28 days of restricted feeding (NFW1); 28 days without withdrawing their feed (NFW2). Egg production of postmolt decreased until $3{\sim}4$ days at FW1 and FW2 treatments and until $16{\sim}18$ days at NFW1 and NFW2. 50% recovery of egg production were 7, 6, 7 and 5 week at FW1, FW2, NFW1, and NFW2 treatments, respectively. At day 14 of postmolt, the weight of livers, hearts, and oviducts decreased at molting treatments (P<0.05). Egg quality was improved on egg weight, eggshell thickness, eggshell break strength, and Haugh unit except egg yolk color (P<0.05).

• Korean Journal of Ichthyology
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• v.27 no.2
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• pp.86-94
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• 2015

Egg development and early life history of the endangered species, Microphysogobio rapidus was investigated to get a basic information for biological characteristics and recovery strategy. Eggs were obtained from females by injecting Ovaprim (0.5 mL/kg) and artificially fertilized by dry method in the laboratory. The mature eggs were slightly adhesive and separated with light bluish green and $0.63{\pm}0.02mm$ (n=20) in diameter. Number of eggs in the ovaries were $3,827{\pm}1,225$ (2,850 ~ 5,916). The hatching occurred at 72 hours after fertilization under water temperature of $21{\pm}1^{\circ}C$. The newly-hatched larvae were $2.79{\pm}0.04mm$ (n=10) in total length. At 5 days after hatching, they were average $4.10{\pm}0.07mm$ (n=10) in TL and their yolk sacs were completely absorbed. 30 days after hatching, they became to juvenile stage and reached $9.74{\pm}0.24mm$ (n=10) in TL. At 100 days after hatching, the band patterns and external form were similar to those of adults, average $27.00{\pm}1.94mm$ (n=10) in TL.

• Korean Journal of Ichthyology
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• v.29 no.2
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• pp.101-108
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• 2017

Egg development and early life history of the Korean natural monument fish Hemibarbus mylodon (Pisces: Cyprinidae) were investigated to provide basic data on biological characteristics and ecological recovery. Adult fish were collected from nature and transferred to the laboratory. For the first time, artificial maturation of females and males succeeded after 15 months of indoor culture. Mature eggs and sperm were obtained using Ovaprim injections (0.5 mL/kg) and then the eggs were fertilized using the dry method in the laboratory. The mature eggs were adhesive, turbid, and greyish; they averaged $2.21{\pm}0.06mm$ (n=30) in diameter. The embryos began to hatch about 78 h after fertilization at a water temperature $20{\pm}1^{\circ}C$, and the newly-hatched larvae were $6.6{\pm}0.75mm$ in total length (TL). At 14 days after hatching, the post-larval individuals were $13.5{\pm}0.23mm$ (TL), and their yolk sacs were completely absorbed. Twenty one days after hatching, they entered the juvenile stage and reached $13.5{\pm}0.23mm$ (TL). At 100 days after hatching, their band patterns, external form, and a pair of barbels were similar to those of adults, and they averaged $33.0{\pm}4.25mm$ (TL). The breeding technology and characteristics of early life history obtained in this study will be very helpful for conservation of H. mylodon in nature.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.39 no.4
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• pp.349-356
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• 2006

Gonad development in the sandfish Arctoscopus japonicus was investigated using a histological method. Specimens were collected monthly from April 2003 to March 2004, in the East Sea of Korea. The gonadosomatic index (GSI) of females began to increase in August, reached a maximum in November, and declined sharply in December. By contrast, in males, the GSI began to increase in June and reached a maximum in August. The annual reproductive cycle of A. japonicus can be divided into four successive stages in females: the early growing (January-March), late growing (April-August), ripe and spent (September-November), and recovery (December) stages. Males passed through early growing (January-April), late growing (May-July), ripe and spent (August-November), and recovery (November-December) stages. These results indicate that the spawning season was from October to December. The egg diameter of mature oocytes was 3.12$\pm$0.02 mm. The relationship between fecundity (F$_e$) and body length (BL) was F$_e$=0.4693BL$^{2.6825}$. Fecundity ranged from 483-2,254 eggs in a body length of 14.3-22.9 cm and increased with body length. The body length at 50% maturity was 14.80 cm, which corresponded to an age of 2.40 years.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.46 no.4
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• pp.351-358
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• 2013

A protease inhibitor from fish eggs was fractionated using chromatographic methods. The fractionation efficiency was evaluated in terms of specific inhibitory activity (SIA, U/mg), purity (fold), total inhibitory activity (TIA, U), and recovery (%). The protease inhibitor (PI) from egg extracts of skipjack tuna (ST Katsuwonus pelamis), yellowfin tuna (YT Thunnus albacares) and Alaska pollock (AP Theragra chalcogramma) was fractionated using Sephadex G-50 gel filtration and DEAE-Sepharose CL-6B anion exchange chromatography based on protein size exclusion and net charge, respectively. Fractions exhibiting strong inhibitory activity were contained in the 30-50 kDa fraction on gel filtration and in the range of 0.4-0.7 M NaCl gradient fraction on anion exchange chromatography. The respective TIA and percent recovery of the fraction obtained with gel filtration toward trypsin and $N{\alpha}$-benzoyl-L-arginine-p-nitroanilide (BAPNA) were 2,758.7 U and 29.6% for ST, 1,005.5 U and 25.6% for YT, and 1,267.5 U and 26.0% for AP. Gel filtration chromatography was more effective at fractionating PI than using ion exchange chromatography. These results suggest that fish eggs act as serine protease inhibitors and might be useful for protease inhibition in foodstuffs.