• 한국발생생물학회지:발생과생식
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• 제14권1호
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• pp.7-11
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• 2010

This study attempted to verify the possibility of using germ cell aspiration (GCA) method as a non-fatal technique in studying the life-history of equilateral venus, Gomphina veneriformis (Veneridae) and granular ark, Tegillarca granosa (Arcidae). Using twenty-six gauge 1/2" (12.7mm) needle, GCA was carried out in equilateral venus through external ligament. In granular ark, GCA was performed by preventing closure of the shells by inserting a tongue depressor between the shells while still open. The success rate of sex identification using the GCA method was 95.6% for the equilateral venus (n=650/680) and 94.3% for the granular ark (n=707/750). Mortality of equilateral venus, which spent 33 days under wild conditions, was 13.8% (n=90/650) while the mortality of granular ark, which spent 390 days under wild conditions, was 2.4% (n=17/707). Although we believe that GCA does not appear to cause death in equilateral venus or granular ark, the success rate in employing of this methodology may differ depending on the level of proficiency of the researcher and reproductive stage of the bivalve. This study concludes that GCA is a convenient non-fatal methodology, which can be employed to identify sex and investigate gonadal maturity in Gomphina veneriformis and Tegillarca granosa.

• 한국양식학회지
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• 제20권4호
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• pp.212-218
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• 2007

Reproductive biology (sexual maturity and reproductive cycle) of starry flounder Platichthys stellatus were examined by histological methods. From March 2004 to February 2005, 144 females and males were sampled. Gonadosomatic index (GSI) of female and male were peaked in May and February, respectively. Monthly changes of hepatosomotic index (HSI) showed a negative correlationwith those of the GSI. Changes of condition factor (CF) in female were correlated with gonad maturation, while that of male were no difference all the year round. Based on monthly GSI and gonadal development the reproductive cycle of starry flounder could be divided into four stages: growing stage (September to November), maturation stage (September to February), ripe and spent stage (March to May), and recovery and resting stage (June to August). Biological minimum size of female was 1,074 g. The relationship between fecundity (F) and body weight (BW) of the fish was expressed as $F\;=\;455.86BW^{1.2006}$.

• 한국어류학회지
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• 제30권2호
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• pp.84-91
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• 2018

본 논문은 소양호에 서식하는 내수면어업의 주요 수산자원 중 하나인 쏘가리(Siniperca scherzeri)의 성숙과 산란에 관하여 연구하였다. 본 논문에 사용된 쏘가리는 2014년 4월부터 11월까지 정치망과 자망을 통해 채집하였고, 암컷이 204개체로 전장범위는 113~365 mm이었고, 수컷은 197개체로 전장 범위가 140~342 mm이었다. 산란기가 시작되는 5월의 수온은 $15^{\circ}C$를 나타냈으며, 점진적으로 높아져 7월에 $26^{\circ}C$를 나타내었다. 암컷의 생식소 숙도지수(GSI)는 5월에서 7월까지 각각 2.3%, 4.6%, 3.1%로 나타났고, 수컷의 경우 8.0%, 6.6%, 4.5%로 나타났다. 난소 조직은 5월에 많은 수의 샘플이 중숙으로 관찰되었으며 6월에는 대다수가 성숙, 7월에는 완숙 및 방란으로 관찰되었다. 정소 조직의 경우에도 마찬가지로 5월에는 대다수가 중숙, 6월에는 성숙, 7월에는 방중으로 관찰되었다. 월별 성숙도와 생식소 숙도지수 (GSI), 생식소의 조직관찰을 통한 분석결과, 소양호에 서식하는 쏘가리의 산란기는 5월에서 6월로 추정되었다. 또한 군성숙도를 분석한 결과, 암컷 쏘가리의 50% 성숙체장은 245.16 mm로 나타났다.

• 한국양식학회지
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• 제13권3호
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• pp.245-251
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• 2000

1997년 12월부터 1998년 3월까지 경상북도 영덕~울진 인근 해역의 수심 170~250 m에서 채집된 대게, Chionoecetes opilio의 크기조성에 따른 생태학적인 특징과 성숙에 대해 연구하였다. 갑폭 조성에서, 암컷과 수컷의 주 출현개체군은 각각 70~80 mm (60.1%), 80~90 mm (64.2%) 체급군이었다. 갑장 및 갑폭의 관계 (암컷 CL=0.951 CW+0.2033, 수컷 CL=0.9387 CW+2.0811)는 암수 모두 갑장에 비해 갑폭이 약간 끈 것으로 나타났으며, 갑폭과 체중의 관계 (암컷 BW=0.0123 CW$^{2.1693}$ , 숫컷 BW=0.0056 CW$^{2.3694}$)에서 체중의 변화는 동일 체급군에서 숫컷이 암컷보다 무겁게 나타났다. 또, 갑폭 64.9-96.0 mm에서 암컷의 평균 포란수(F=8.5285 CW$^{2.0498}$ )는 35,000~114,000개로 조사되었다. 갑폭에 대한 성숙개체 (암컷 외포란 및 난소 발달, 수컷 : vasa deferentia 관찰)의 비율은, 암컷의 경우 갑폭 54.2 mm 에서 약 50%, 갑폭 60.1 mm 이상에서는 100%였으며, 갑폭 42.3 mm 이하에서는 성숙개체가 관찰되지 않았다 수컷의 경우는 갑폭 58.8 mm, 72.0 mm 이상에서 각각 50%, 100%의 성숙개체 출현율을 나타냈으며, 갑폭 48.4 mm 이하에서는 성숙개체가 관찰되지 않았다.

• 한국수산과학회지
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• 제53권1호
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• pp.50-56
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• 2020

Determination of the precise size at sexual maturity is very important for science-based stock assessment and fisheries resource management. In this study, two different models, (1) a visual method and (2) a gonadosomatic index (GSI) method, were employed to estimate length at sexual maturity of the small yellow croaker Larimichthys polyactis in the Yellow Sea of Korea. The visual method is a common qualitative method using visual gonadal identification. Conversely, the GSI method is a quantitative method using the GSI, which can be easily and precisely collected. We compared results from these methods to determine the best approach, and to examine the practicality of the GSI method. Logistic regression of the maturity ogive was conducted using a general linear model (GLM) with the R statistics program. Also, the bootstrapped 95% confidence intervals of all estimates were calculated. The best-fit model was the visual method (R_Mc²=0.805, AUC=0.989, L₅₀=15.1). Among models using the GSI method, the model computing GSI_ref=0.94 was the best-fit model (R_Mc²=0.792, AUC=0.989, L₅₀=15.2). There was no significant difference between the two models, evidencing the effectiveness and accuracy of the GSI method.

• 한국수산과학회지
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• 제56권3호
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• pp.315-323
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• 2023

The maturity and spawning of the large yellow croaker Larmichthys crocea were investigated using samples randomly collected in the Jeju coastal area, Korea. We analyzed monthly changes in maturity stages, gonadosomatic index (GSI), and egg diameter. Additionally, we verified fecundity by size class and total length (TL) at sexual group maturity at 50%, 75%, and 97.5%, as well as by sex ratio (female vs. male). The overall sex ratio of females to males was 1:0.42. The GSI values showed a peak in October, but the spawning season, revealed by the microscopic analysis of gonadal tissue of L. crocea was from October 2021 to March 2022, with the main spawning period from October to November. The fecundity (F) of female L. crocea ranged from 39,232 eggs at 20 to 29.9 cm to 251,003 eggs at 50 to 59.9 cm, with the relationship between TL and F being 80.244TL-1641.6. In females, TL at 50%, 75%, and 97.5% maturity was 22.4, 24.3, and 29.0 cm, respectively.

• 한국수산과학회지
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• 제50권3호
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• pp.296-301
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• 2017

We conducted a study to 1) determine the indicators of gonadal maturity in male and female Korean walleye pollock Theragra chalcogramma for the purposes of artificial insemination; 2) establish the RNA/DNA ratio of mature eggs in this species; and 3) monitor the effect of refrigerated storage on egg viability and the motility of sperm collected from dead adult males. During the spawning season, the color of female gonads changed from orange to transparent, and that of male gonads changed from pale orange to milky white. The DNA content and RNA/DNA ratio of mature eggs were maintained without significant changes for approximately 6 h when eggs were preserved at $4^{\circ}C$. Sperm could be obtained from both milt and undiluted semen. Sperm obtained from milt ceased moving on the second day after isolation, while over 60% of sperm obtained from semen showed movement until the 13th day. Seven attempts were made to artificially inseminate mature eggs, of which two resulted in successful fertilization. The successful inseminations produced 94,000 and 5,000 fertilized eggs, respectively. This study shows that artificial insemination of walleye pollock is a viable strategy when natural propagation is not possible.

• 한국가금학회:학술대회논문집
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• 한국가금학회 2000년도 제17차 정기총회 및 학술발표
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• pp.88-90
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• 2000

Although primordial germ cells(PGCs) have been used in the production of germline chimera, efficiency has not been satisfactory. The Present study was conducted to improve efficiency of germline chimera production using the cultured gonadal PGCs(gPGCs). Germline chimeric chickens were produced by transfer of cultured gonadal primordial germ cells from Korean Ogol Chicken (KOC) to White Leghorn (5.5-day-old) and cultured in vitro for 10 days. Approximately 200 gPGCs (2-day-old) recipient embryos from which blood had been withdrawn via the dorsal aorta prior to the injection. Recipient embryos were incubated until hatching. Germline chimerism of the chickens reaching maturity was examined by mating them with Korean Ogol Chicken. Donor-derived offspring were identified as germline chimeric chickens based on their feather color. The frequency of germline transmission of donor PGCs ranged 1.9∼60.7%. There was no difference between both sexes. Therefore, it can be concluded that efficiency of germline chimerism can be improved via using cultured gPGCs.

• Fisheries and Aquatic Sciences
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• 제14권4호
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• pp.403-410
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• 2011

Scartelaos gigas is an amphibious mudskipper species that inhabits mud flats in Korea, China, and Taiwan. This fish is at risk of extinction because of its very restricted habitat and overexploitation. Information about this fish's reproductive characteristics is needed for species conservation. The sexual maturity and early life history of S. gigas were investigated through histological methods and direct observation of eggs in the wild, respectively. In total, 560 individuals of S. gigas were collected with the aid of fishermen from March 2003 to October 2003 at Jung-do Island, southwest Korea. Through microscopic observations of gonadal development, it was determined that S. gigas of both sexes were immature in April, but began to reach maturity in May, and were then fully mature by June, which was maintained until July. In August, some female fish developed early oocytes, but by September oocytes were observed to have degenerated and had been absorbed. Spawned eggs were elliptical and had an average size of 1.37 mm (long axis) by 0.69 mm (short axis). The newly hatched larvae (3.03 mm total length, TL) had an open mouth and anus, two melanophores near the anus, and one large melanophore between the 18th and 19th myomeres. The larvae (3.18 mm TL) showed absorption of the yolk and oil globule within 5 days after hatching and became prelarvae. This species should be considered vulnerable or conservation-dependent, and thus parental fish need to be protected from fishermen during the main spawning season (June).

• Animal cells and systems
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• 제13권3호
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• pp.339-344
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• 2009

This study aims to find out the effect of heavy metals, as is the case of EDCs (endocrine disrupting chemicals), on reproductive endocrine disruption of aquatic animals. In the present experiment zinc, which is a heavy metal well known for its androgenous activity, was used. The experimental period was 24 weeks, starting in November during the inactive stage of the clam's reproductive cycle. The experimental groups were composed of one control condition and three zinc exposure conditions (0.64, 1.07, and 1.79 mg/L). The sex ratio (F:M) was 1:1.06 in the control group and 1:1.70 in all the exposed group, illustrating the tendency for higher proportion of males with increases in zinc concentration. Gonad maturity was higher in 1.07, and 1.79 mg/L groups compared to the control group, with higher maturity observed in males than females. Intersex individuals made up 24.7% of the exposed group, while females exhibited a higher ratio than the males with increasing zinc concentration. The results of this study indicate that zinc functions as an androgenic effector on the reproduction of Gomphina veneriformis.