• 수산해양교육연구
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• 제24권6호
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• pp.1003-1012
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• 2012

The gonadosomatic index (GSI), sex steroid hormones and gonadal development of roughscale sole Clidoderma asperrimum cultured in indoor tank were investigated to evaluate its sexual maturation and reproductive cycle. The highest GSI values of female and male were $6.91{\pm}4.03$ (May) and $0.16{\pm}0.08$ (August), respectively. The reproductive cycle would be classified into four successive developmental stages: growing stage (December to February), maturation stage (March to April), ripe and spawning stage (May to June), recovery and resting stage (July to November). The highest plasma testosterone (T) and estradiol-$17{\beta}$ ($E_2$) levels of female were $259.4{\pm}76.8$ and $633.3{\pm}182.5$ pg/mL, respectively in May. Also $17{\alpha}$, $20{\beta}$-dihydroxy-4-pregen-3-one ($17{\alpha}$, $20{\beta}$-OHP) levels of female peaked in April before spawning season ($244.2{\pm}42.5$ pg/mL). The highest plasma testosterone (T) and 11-ketotestosterone levels of male were $231.0{\pm}46.0$ and $273.9{\pm}54.5$ pg/mL, respectively in April. But there was no significant difference in $17{\alpha}$, $20{\beta}$-OHP.

• 한국발생생물학회지:발생과생식
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• 제9권2호
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• pp.95-103
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• 2005

한국 제주도산 해가리비(Amusium japonicum japonicum)를 대상으로 생식주기, 생식소중량지수(GSI), 난경조성 변화, 군성숙도, 성적 성숙체장(50% 군성숙도) 및 성비를 조직학적 관찰 및 생체 측정에 의해 조사하였다. 해가리비는 자웅이체이다. 생식소 중량지수(GSI)의 월별 변화는 생식주기와 유사한 양상을 보였다. 완숙 난모세포들은 직경이 약 $70{\sim}90\;{\mu}m$ 정도이며, 두터운 난막을 가지는 특징을 가지고 있다. 산란기는 11월부터 1월 사이이며, 주 산란은 해수 수온이 낮은 $11{\sim}12$월 사이에 일어난다. 월별 난경 조성 변화를 보면, 산란기 중 산란빈도 수는 2회 이상으로 추정되지만, 산란기간은 1년에 한번이다. 본 종의 생식주기는 초기 활성기($4{\sim}6$월), 후기 활성기($6{\sim}9$월), 완숙기 ($10{\sim}11$월), 산란기($11{\sim}1$월), 그리고 퇴화 및 휴지기($2{\sim}4$월)의 연속적인 5단계로 나눌 수 있다. 각장 $85.1{\sim}90.0mm$인 암 수의 해가리비 군 성숙도는 50%이었고, 각장 90.0mm 이상인 개체들은 100%이었다. 이 개체군에서 성적으로 성숙한 암 수 개체들의 각장(군 성숙도 50%) 크기는 각각 86.96mm와 86.59mm이었다. 각장 85.1mm 이상인 암 수 개체들의 성비는 1:1로 유의한 차이를 보이지 않았다($X^2=0.18$, p>0.05). 조사된 해가리비의 조직학적 절편에서 자웅동체인 개체는 발견되지 않았다.

• 한국발생생물학회지:발생과생식
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• 제17권3호
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• pp.247-255
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• 2013

The gonadsomatic index (GSI) of mottled skate was the highest in April, GSI and HSI showed a reverse phase for its reproductive cycle. The fish had one pair of egg capsules, having 1 to 7 fertilized eggs, and spawned all the year round. When surveying the reproductive characteristics of females over 63 cm in disc width, we found the spawning peak was between April to June, and the appearance ratio of egg capsules was the highest in May (32.1%). The eggs were hatched at $8^{\circ}C$, $13^{\circ}C$, $18^{\circ}C$, water temperature (12.8 to $24.2^{\circ}C$), and the best hatching temperature was $18^{\circ}C$. The number of fish hatched was 4 to 5 fish/egg capsules, and the hatching rate was 100%. The sex ratios of hatching larvae were 45.5% female and 54.5% male. Therefore this study will provide fundamental data and information for artificial reproduction of the mottled skate.

• 수산해양기술연구
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• 제47권3호
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• pp.194-202
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• 2011

Maturation and spawning of the Shotted halibut, Eopsetta grigorjewi was investigated based on the samples captured in South Korean waters from January 2008 to December 2009. Gonadosomatic index began to increase in December, and reached maximum between January to March. After spawning it began to decrease from May. Reproductive season was estimated to January-April, with peak in February. Fecundity was proportional to the size of the female, with the clutch size varying from 170,000 eggs in the smallest female (total length, 28.9cm) to 1,300,000 eggs in the largest (total length, 41.5cm). Size at 50% sexual maturity (TL50), determined from mature females, was 28.8cm. Annual reproductive cycles of this species could be divided into six successive stages; immature stage (May-October), nucleolus stage (November-January), yolk vesicle stage (January-February), vitellogenic and ripe stage (January-April) and spent stage (April-May).

• 수산해양기술연구
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• 제46권4호
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• pp.368-375
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• 2010

Maturation and spawning of the Blackthroat seaperch, Doderleinia berycoides were investigated based on the samples captured in Korean waters from January 2008 to December 2009. Gonadosomatic index began to increase in June, and reached maximum between July to September. After spawning it began to decrease from October. Reproductive season was estimated to July-September, with peak in August. Fecundity was proportional to the size of the female, with the clutch size varying from 115,500 eggs in the smallest female (TL〓28.2cm) to 652,000 eggs in the largest (TL〓33.5cm). Size at 50% sexual maturity ($TL_{50}$), determined from mature females, was 29.6cm. Annual reproductive cycles of this species could be divided into six successive stages; immature stage (October-May), nucleolus stage (June-July), yolk vesicle stage (July-August), vitellogenic stage (June-September), ripe and spent stage (August-October).

• 한국패류학회지
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• 제22권1호
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• pp.13-22
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• 2006

2005년 1월부터 12월까지 충청남도 서천군 비인만 앞바다 조간대에서 채집된 큰구슬우렁이를 대상으로 생식소중량지수(GSI), 난자형성 중 난황형성과정 및 생식주기를 세포, 조직학적 관찰과 형태측정 자료에 의해 조사하였다. GSI의 월별 변화는 생식소발달과 유사한 양상을 보였다. 초기 난황형성 단계 난모세포에서 골지체와 미토콘드리아가 지방적 및 난황과립의 형성에 관여되었다. 후기 난황형성 단계의 난모세포에서 조면소포체와 다포체가 세포질 내에서 단백질성 난황과립에 관여하였다. 성숙 난황과립은 주소체 (중앙중심), 가장 자리에 표면층, 그리고 이들을 둘러싼 한계막의 3 가지 성분으로 구성되어있다. 산란기는 6월 초-8월 말 사이 이었고, 주산란은 수온이 $19^{\circ}C$ 이상인 7-8월에 일어났다 암컷의 생식주기는 초기 활성기 (12-2월), 후기 활성기 (2-3월), 완숙기 (4-7월), 산란기 (6-8월), 회복기 (8-11월) 의 연속적인 5 단계로 구분되었다. 완숙난모세포의 크기는 직경이 $250-270{\mu}m$이었다.

• 수산해양기술연구
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• 제45권4호
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• pp.243-250
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• 2009

Maturation and spawning of the jack mackerel, Trachurus japonicus was investigated based on the samples captured in the coastal waters around Jeju Island from January 2007 to December 2008. Gonadosomatic index began to increase in March, and reached a maximum between April to June. After spawning it began to decrease from August. Reproductive season was estimated to March-July, with peak in April. Fecundity was proportional to the size of the female, with the clutch size varying from 33,493 eggs in the smallest female(FL=27.0cm) to 627,061 eggs in the largest(FL=40.6cm). Size at 50% sexual maturity(FL50), determined from mature females, was 26.6cm FL. Annual reproductive cycles of this species could be divided into six successive stages; immature stage(September-December), nucleolus stage(January-February), yolk vesicle stage(February-March), vitellogenic stage(March-April), ripe stage(April-July) and spent stage(July-September).

• Fisheries and Aquatic Sciences
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• 제12권4호
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• pp.276-285
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• 2009

Despite great commercial interest, relatively little has been described about molecular mechanism of bivalve reproduction. We investigated genes involved in ovarian maturation of the Yesso scallop, Patinopecten yessoensis. GSI index and histological analysis revealed that maturation of ovary begin in February and spawning period is from April to June which is similar to the previous study in the East Sea. As result of combination analysis of differential display RTPCR (DDRT-PCR) and histological examination, vitellogenin (Vg), ferritin (Ft) and ADT/ATP carrier protein (ACC) were identified as differently expressed genes in maturating ovary. Endpoint RT-PCR results showed that Vg is ovary-specific genes whereas Ft and ACC are expressed ubiquitously suggesting that Vg can be good molecular markers for ovarian development and sex determination in bivalves. Quantitative PCR results revealed that Vg were expressed highest during growth stage and appears to play a major role in oocyte maturation. On the contrary, expression of Ft was highest after spawning stage, which suggests that up-regulation may be involved in spawning and inactive stages in which the scallops recover from spawning. In addition, high level of the mitochondrial gene, ACC, may play a role in energy metabolism in maturating oocytes. Isolation and molecular studies of these key genes will expand our knowledge of the physiological changes from various exogenous factors including temperature, salinity, pH, even or numerous endocrine disrupting chemicals (EDCs) during reproductive cycle. In addition, further study of these genes implicates various industrial applications including the stable seed production, increased food quality, or economic aquaculture system.

• Fisheries and Aquatic Sciences
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• 제10권2호
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• pp.74-85
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• 2007

Pacific anchovy (Engraulis japonicus) eggs were collected during the spawning season (2000-2003) using a revised ring net in the coastal waters adjacent to the Geum River Estuary in the West Sea of Korea (Yellow Sea). Anchovy eggs were present from May to September, showing a peak in spawning from June to July when the water temperature and salinity were $17-27^{\circ}C$ and above 30.00 psu, respectively. During the main spawning season, no clear diel cycle (regarding the 24-h sampling period of dusk, night, dawn, and daytime) was detected in the vertical distribution of anchovy eggs near Eocheong Island (50-60m depth). Judging from the developmental stages of the collected eggs, it appeared that anchovies spawned mostly at night and that the eggs hatched at dusk and during the night. The density of anchovy eggs was high in the southwest-northeast direction in June, and spawners appeared to move offshore in July. Mean egg density was higher in June 2002 than in June 2003 when water temperatures and salinities were lower. This study on the spatiotemporal distribution of eggs will contribute to developing management plans for the Pacific anchovy in Korea.

• 한국패류학회지
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• 제9권2호
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• pp.1-15
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• 1993

The reproductive ecology of the purple shell, Rapana venosa was investigated by the histological observations on depositions of the egg capsules, and hatching of larvae in the laboratory and the subtidal zone of the vicinity of piung-do, Chollabud-do, west coast of korea, for one year from June 1992 to May 1993. The results are summarized as follows:1. Rapana venosa is dioecious in sex. The ovary is composed of a number of ovarian lobules, and the testis comprises a number of ovarian lobules, and the testis comprises of gonads could be classified into 4 stages in males and 5 stages in females: 1) growing stage(in female subdivided into 2 stages of early and late growing stage). 2)mature stage. 3)spent stage or copulationstage. 4)rdcovering stage. The early growing stage in females of the purple shell was in September through February, late gorwing stage was in October to March, mature stage was in September to January, mature stage was in September to July, copulation stage was in Februaty to June and recovering stage in April to October.3. Spawning occurred 3-4 times at intervals of 1-3 days, and completed within 10 days from the beginning of spawning during the spawning season of the year.4. From the results of laboratory and field observations, egg masses are composed of a number of egg capsules, egg masses are occurred from May to late August, and in mid August depositions of egg mass in composed of 90-113 egg capsules, fecundity in an egg capsule was ranged 984 to 1,241 eggs(average 1,096 egg). Therefore, fecundity in total egg capsules spawned per individual during the spawning season is estimated as approximately 320,000 to 450,000 egges.5. The incubation period during deposition of an egg capsule to hatching larvad tood 17 days at 18.3-20.4%C(water temperature)and 1.021 (specific gravity fo sea water).