• 한국수산과학회지
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• 제42권1호
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• pp.48-55
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• 2009

The gonad maturation and spawning of blue crab, Portunus trituberculatus (Miers, 1876) using samples caught by trammer net in the western coast of Korea from January to December. The gonadosomatic index (GSI) showed the highest value of 15.0 in June and lowest value of 1.29 in August. Hepatosomatic index (HSI) showed the lowest in the spawning season from June to July. Thereafter, from August the value started to increase to 5.77 in December, showing an adverse trend against GSI. In the histological studies of the female reproductive organ, the gonad filled with primary oocytes from January to February and secondary oocytes in May. The female gonads mature from June, and mature and immature groups could be distinguished from December to February or March. In August, female developed another cycle of gonad development, showing new primary oocytes in the gonads again. Some of female crabs had receptaculum filled with already active sperm cells in it from March to May. In the time of August to September, almost all the females had the sperm sacs in the receptaculum. From the result, the coupling period estimated from August to September. Total RNA and DNA values of the crabs were highest in May (2.51, $0.57{\mu}g/mg$). The DNA value remained unchanged except for the value in May ($0.09-0.13{\mu}g/mg$). while RNA value was lowest in January ($1.08{\mu}g/mg$). The RAN/DNA ratio was the lowest (6.23%) in May and highest (18.05%) in July. The value of correlations coefficient between body weight and fecundity of the crabs was higher that of between carapace width and fecundity.

• 한국수산과학회지
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• 제37권5호
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• pp.385-392
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• 2004

Gonadal development, gametogenesis, reproductive cycle, gonad index, and flesh weight rate of the murex shell (Ocenebra japonica) collected from the rocky intertidal zone of Buan-gun, Jeollabuk-do, Korea were investigated by means of histological method from January to December 2002. O. japonica had separate sexes, and was oviparous. The gonad was widely situated on the surface of the digestive gland located in the rear of the spiral flesh part in the shell. The male penis was located near the two tentacles. The ovary was composed of a number of oogenic follicles, and the testis was composed of several spermatogenic tubules. The size of ripe oocyte was approximately $140{\mu}m$ in diameter. The gonad index (GI) began to increase in March $(33.24{\pm}2.33)$ and reached the maximum in June $(47.77{\pm}1.90)$ Thereafter, the values decreased from July $(45.12{\pm}3.60)$ to October $(19.32{\pm}2.91)$. The flesh weight rate (FWR) began to increase in January $(25.93{\pm}1.32)$ and reached the maxium in May $(31.78{\pm}1.09)$ Thereafter, the values decreased from June $(31.50{\pm}0.66)$ to October $(24.09{\pm}1.60)$. The reproductive cycle could be classified into five successive stages: early active (October to April), late active (January to June), ripe (May to September), spawning (July to September) and recovery (September to February). The reproductive cycle was closely related to the seawater temperature.

• Fisheries and Aquatic Sciences
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• 제19권1호
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• pp.5.1-5.7
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• 2016

The study was conducted to know the cyclic changes in gonadal maturation and to investigate the developmental stages of oocytes and testicular germ cells of an air-breathing fish, Channa striata. Fish were sampled monthly from lentic and lotic environments of three geographical locations of Bangladesh from December to November and the histological analysis of their gonad was done to evaluate the objectives. The highest mean GSI was $5.95{\pm}0.20$ for female in July and $0.14{\pm}0.01$ for male also in July showing that the gonadal development reached its peak during this month. The highest mean oocyte diameter was $1257.50{\pm}24.17{\mu}m$ observed in July implying that the oocyte reached maturity in this month. Histological study of ovary revealed the evidence of early yolk granule stage and late yolk granule stage from April to July. In case of male four stages of spermatogenesis were distinguished and spermatozoa were highly abundant in June and July. So the monthly pooled values of GSI and the analysis of gonadal histology indicated that the peak breeding season of C. striata occurred in July in the lentic and lotic environments. Samples collected from lentic and lotic habitats are suggestive of no difference in the development of the gonad. The results of the present study will be useful for selective breeding programme, conservation and sustainable fishery management of C. striata in its natural habitat.

• 한국양식학회지
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• 제1권2호
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• pp.121-133
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• 1988

고가의 식품으로 이용되는 말똥성게의 생식소의 소비가 증가됨에 따라 연안의 말똥성게 자원은 계속 감소하고 있어 이 종류에 대한 양식 기술개발은 중요한 연구 과제이다. 따라서 본 연구는 말똥성게를 실내에서 양식할 경우 먹이로서 신선한 해조류를 대치할 수 있는 육상식물을 조사하였다. 해조류 6종류 (미역, 구멍갈파래, 지충이, 개지누아리, 모자반, 곰피), 육상식물 5종류 (시금치, 상치, 무우잎, 배추, 케일), 동물성 먹이 2종류 (바지락. 쇠고기)를 대상으로 말똥성게의 선택적 및 비선택적 식성과 영양 효과를 비교한 결과, 말똥성게의 먹이로서 육상 식물의 이용이 가능하였다. 미역을 공급한 경우 말똥성게의 체중의 성장은 가장 높았으나 생식소지수는 시금치, 무우잎 또는 상치를 공급할 경우가 미역의 경우보다 더 높았다. 시금치와 무우잎의 공급은 생식소가 성장하는 계절에 적합하고, 각이 성장하는 시기에는 상치 또는 배추가 효과적일 것으로 판단된다. 특히 무우잎은 식용으로 이용하지 않고 버려지므로 무우잎을 이용한 말똥성게의 양식은 매우 경제적일 것이다.

• 한국어류학회지
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• 제6권2호
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• pp.206-221
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• 1994

산란기 직전의 산천어, Oncorhynchus masou 2배체와 유도 3배체를 대상으로 체장과 체중 및 형태측정을 실시하였다. 체중, 내장괴 제거 체중, 체장, dressing 비, 비만도, 생식소 무게와 생식소 지수, 복강두께 및 내장괴 무게와 내장괴 지수가 조사되었으며 체둘레 측정이 등지느러미, 배지느러미 및 등지느러미의 각 종단면에서 이루어졌다. 종단면 면적과 2가지 복강두께 형질이 등지느러미, 배지느러미 및 뒷지느러미의 종단면에서 조사되었으며 아울러 각 종단면에서의 높이, 전체높이, 폭, 3가지 체형질과 9가지 종단절단형질이 조사되었다. 2배체의 체장과 체중은 유도 3배체와 비교시 크게 나타났으며 dressing 비, 생식소 무게, 생식소지수, 내장괴 지수 및 간 지수 역시 2배체가 유도 3배체 보다 크게 나타났다. 반면 유도 3배체는 2 배체에 비해 가슴지느러미 및 등지느러미 종단면에서의 1가지 복강두께 형질과 일부 종단형질에서 높은 치를 나타내었다. 2배체에 비해 유도 3배체의 이러한 형질특성은 유도 3배체 자체의 불임에 기인된 것으로 산란기 직전 유도 3배체의 경제적 가치성을 시사한다고 할 수 있다.

• 한국발생생물학회지:발생과생식
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• 제14권3호
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• pp.179-184
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• 2010

Water temperature influences on various key biological events in fish, but the internal pathway of the temperature effects are not well understood. Heat shock proteins (HSPs), known to respond in the level of cells to many environmental factors including temperature, could improve our understanding on the pathway. Some biological processes such as gonadal development and sex differentiation in the Nile tilapia Oreochromis niloticus is particularly sensitive to water temperature. In this study, we have investigated the expressions of HSP70 and HSP90 genes in young tilapia at an ordinary temperature ($28^{\circ}C$) and elevated water temperature ($36^{\circ}C$). The distribution of the expressions of HSP70 and HSP90 mRNA in this species were found to be almost ubiquitous, being detected in all tissues studied here (brain, gonad, liver and muscle), suggesting the house keeping functions of these genes. Heat shock by elevating temperature from $28^{\circ}C$ to $36^{\circ}C$ significantly increased the expression of HSP70 mRNA in the gonad, liver and muscle for several hours (P<0.05) (brain tissue was not examined for this). The increased level of HSP70 gene expression recovered to the level at control temperature ($28^{\circ}C$) when fish were kept continuously at high temperature ($36^{\circ}C$) for 24 hours. Contrary to this, expression of HSP90 mRNA did not show significant increase in the gonad and muscle by the same heat shock (P>0.05), except in the liver where the expression of HSP90 mRNA increased continuously for 24 hours at $36^{\circ}C$. The results obtained in this study suggest that response to temperature change in different tissue or organ may utilize different heat shock proteins, and that HSP70 may have some importance in temperature-sensitive gonadal event in the Nile tilapia.

• Ocean and Polar Research
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• 제43권4호
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• pp.365-370
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• 2021

Manila clam Ruditapes philippinarum is present at high rates of density in tidal flats in Cheonsu Bay on the west coast of Korea, where clams often exhibit mass mortalities in late summer. We monitored the pathologic condition of clams at Hwangdo tidal flat (HD) to understand the parasitic impacts on clam fitness. Manila clams were fully ripe in July and spawned during August and September, as the histology indicated. The histology revealed that clams in HD tidal flats were heavily infected by the protozoa parasite Perkinsus olseni, as the monthly prevalence ranged from 53% (September) to 93% (August). In addition, Manila clams were co-infected by the metazoan parasite Cercaria tapetis and Parvatrema duboisi with the prevalence of 0-33% and 0-14%, respectively. Massive hemocyte infiltration and subsequent inflammation were commonly observed from the gills of P. olseni infected clams. Clusters of P. olseni trophozoites and heavy hemocyte infiltration were also observed from the female gonad, suggesting that P. olseni interferes with host gonad maturation. The larval trematode occupied almost the entire host gonad, resulting in gonad castration. In addition, Metacercaria of P. duboisi were observed from the subsurface of the mantle. Ray's fluid thioglycollate medium assay (RFTM) indicated that clams collected in August and September contained approximately 4.0×106 P. olseni cells/g gills. Condition Index (CI) declined gradually from spring to early summer, and the decline in CI was interpreted as a consequence of the heavy parasitism, as the parasites drain the host's net energy to be used in somatic growth and gamete production.

• 한국발생생물학회지:발생과생식
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• 제16권3호
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• pp.185-193
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• 2012

For the gonadal sex management of younger longtooth grouper (Epinephelus bruneus), this work investigated the timing and histological process of ovary differentiation and oocyte development of longtooth grouper larvae and juvenile. Specimens (from 1 to 365 DAH) were collected for gonadal histological study from June 2008 to August 2009. Rearing water temperature was ranged from 20 to $24^{\circ}C$. The primordial germ cells could be observed from 10 to 15 DAH, while undifferentiated gonad occurs from 20 to 50 DAH in longtooth grouper. The initial ovarian phase was 60 to 110 DAH with the formation of ovarian cavity and the increased in size of gonad. The ovarian phase started at 140 DAH with appearance of oogonia. The gonad at 365 DAH appeared to have full of oogonia and primary growth stage oocyte. Formation of ovarian cavity indicates that the ovarian differentiation beginning at 60 DAH in longtooth grouper. The gonads in longtooth grouper differentiated directly into ovaries in all fish examined.

• 한국환경과학회지
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• 제22권1호
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• pp.37-45
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• 2013

The monthly variations of blood characteristics and RNA/DNA of black sea bream, Acanthopagrus schlegeli, habituated in Geojae costal area were analysed to determine health condition of natural stocks in terms of gonad maturation and spawning season from March 2010 to February 2011. Spawning season determinated by gonadosomatic index is from June to August. RNA/DNA ratio of black sea bream muscle was strongly correlated with spawning season. During the gonad maturation RNA/DNA ratio in dorsal muscle tissue was decreased contrast to rapid increase during spawning season. Blood composition factors increased in terms of gonad maturation are aspartate aminotransferase, cholesterol, triglyceride, total protein, glucose, globulin, alkaline phosphatase and inorganic phosphate. Other blood factors increased during spawning season are alanine aminotransferase, blood urea nitrogen, uric acid and lactate dehydrogenase.

• Fisheries and Aquatic Sciences
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• 제2권2호
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• pp.142-148
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• 1999

Monthly changes in the gonad index (GI), egg-diameter composition, gonadal development, reproductive cycle of the ark shell, Scapharca subcrenata, were investigated by histological method and morphometric data. This species is dioecious and oviparous. The gonad is located among the subregion of mid-intestinal gland, digestive diverticula and the outer fibromuscular layers compacted by the fibrous connective tissues and muscle fibers. The gonad index sharply increased in May, reached the maximum value in June, and then gradually decreased from July to December. The reproductive cycle of this species can be divided into six successive stages: early active stage (January to May), late active stage (June to July), ripe stage (June to August), partially spawned stage (July to September), degenerative stage (August to December), and resting stage (January to April). S. subcrenata spawns once a year between July and early September, and the main spawning occurred between July and August when the water temperatures were above $20^{\circ}C$. This evidence suggest that timings of maturation and spawning are closely related to water temperatures. Even though the spawning period was once a year, it is assumed that the number of spawning frequencies (broods) may occur more than twice during the spawning season.