• 한국발생생물학회지:발생과생식
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• 제20권3호
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• pp.227-235
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• 2016

Ultrastructural studies on oocyte development and vitellogenesis in oocytes, and the functions of follicle cells during oogenesis and oocyte degeneration were investigated to clarifyb the reproductive mechanism on vitellogenesis of Scapharca subcrenata using electron microscope observations. In this study, vitellogenesis during oogenesis in the oocytes occured by way of autosynthesis and heterosynthesis. Of two processes of vitellogenesis during oogenesis, the process of endogenous autosynthesis involved the combined activity of the Golgi complex, mitochondria and rough endoplasmic reticulum. However, the process of exogenous heterosynthesis involved endocytotic incorporation of extraovarian precursors at the basal region of the oolema of the early vitellogenic oocytes before the formation of the vitelline coat. In this study, follicle cells, which attached to the previtellogenic and vitellogenic oocytes, were easily found. In particular, the follicle cells were involved in the development of previtellogenic oocytes by the supply of nutrients, and vitellogenesis in the early and late vitellogenic oocytes by endocytosis of yolk precursors. Based on observations of follicle cells attached to degenerating oocytes after spawning, follicles of this species are involved in lysosomal induction of oocyte degeneration for the resorption phagosomes (phagolysosomes) in the cytoplasm for nutrient storage, as seen in other bivalves. In this study, the functions of follicle cells can accumulate reserves of lipid granules and glycogen particles for vitellogenesis from degenerating oocytes after spawning.

• Ocean Science Journal
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• 제41권4호
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• pp.211-219
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• 2006

A comparison was made of population of the economically important cockle Anadara (=Scapharca) broughtoni (Bivalvia, Arcidae) inhabiting different areas of the Razdolnaya River estuary at the head of Amurskii Bay (Peter the Great Gulf, East Sea). Also, changes in cockle population density and structure, as well as in cockle growth rates during the last 20 years were studied. In all years of investigation, the morphometrical parameters and growth rates of cockles were smaller at the sites located close to the River mouth than farther down-estuary. The differences can be attributed to higher concentration of suspended particulate matter, decreased salinity and water temperature, as well as a longer exposure to these unfavorable environmental factors at sites located close to the River mouth, compared to farther sites. For two decades, cockle population density had decreased by almost 30 times at some sites in the River estuary. The main reason for this population decline is commercial over-fishing of the cockle. Besides, for the last 20 years, linear parameters of the cockles in the population decreased approximately by 30% and weight parameters, almost two times. Cockle growth rates also decreased for this period. Evidently, these facts are due to the damaging effect of dredging.

• Fisheries and Aquatic Sciences
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• 제12권4호
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• pp.331-338
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• 2009

This study presents physiological rates of respiration and excretion, clearance rate, and assimilation efficiency of the ark shell Scapharca broughtonii, determined during 2007 from specimens collected in Gamak Bay on the south coast of Korea. Physiological parameters were measured monthly under static, laboratory controlled conditions with ambient conditions, and measurements were performed seasonally in order to estimate scope for growth and its probable sources of variation. Temperature directly influenced respiration and excretion. Clearance rates showed a tendency to be low during May-August, which is a period of gametogenesis. Assimilation efficiency was not significantly different seasonally and was independent of the concentration of chlorophyll a. The scope for growth was negative during high-temperature months (July-August), reflecting the high temperature and low clearance rate, and had its highest positive values during spring and autumn. The energy budget or growth potential of bivalves has been applied to other economically important species. Data on the physiological parameters and scope for growth of S. broughtonii obtained in this study will be used to assess the carrying capacity for ark shell cultivation.

• Fisheries and Aquatic Sciences
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• 제10권3호
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• pp.143-149
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• 2007

This study describes spermatogenesis and sperm ultrastructure of the granular ark, Tegillarca granosa using light and electron microscopy. In the active spermatogenic season, the testis comprises many spermatogenic follicles that contain germ cells in different developmental stages. Primary spermatocytes in the pachytene stage are characterized by synaptonemal complexes. The early spermatids are characterized by the appearance of several Golgi bodies, increased karyoplasmic electron density, and tubular mitochondria. The mass of proacrosomal granules consists of numerous heterogeneous granules with high electron density that are about 20 nm in diameter. From the midstage of spermiogenesis, the well-developed mitochondria in the cytoplasm aggregate posterior to the nucleus and surround the proximal and distal centrioles. The proacrosomal granules condense and form a single acrosome with a thin envelope. During late spermiogenesis, the acrosome begins to elongate becoming conical. The sperm is approximately $35.0{\mu}m$ long and consists of a head, midpiece, and tail. The head comprises a round nucleus and a conical acrosome. A micro fibrous axial rod is observed between the nucleus and acrosome. The midpiece has a calyx-like structure with five mitochondria, and the tail, which has the typical "9+2" microtubular system, originates from the distal centriole.

• 한국패류학회지
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• 제23권1호
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• pp.65-104
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• 2007

This catalogue is the result of a four-year survey of the mollusks of Jeju Island, the southernmost island in the Republic of Korea. Forty-eight survey stations were visited, with a total of 82 specific localities being sampled. Literature records were also obtained. Local and world distribution of each species is included. This survey reports a total of 1,072 mollusk species and subspecies; 1,015 marine and 57 land and freshwater. There are 812 gastropods, of which 755 are either entirely marine or have marine affinities. The best represented of the marine families are the Pyramidellidae, Trochidae, and Ovulidae. There are 225 bivalves, none being freshwater species, with the Veneridae, Mytilidae, and Arcidae having the largest number of species. Among the smaller classes there are sixteen Cephalopoda, eleven Polyplacophora, and eight Scaphopoda. Compared to mainland Korea, Jeju Island has a rather small terrestrial mollusk fauna and a depauperate freshwater one, with mainly Palearctic connections. The Helixarionidae and Bradybaenidae are the largest terrestrial families. The marine faunal affinities with the neighboring Japonic and Indo-West Pacific provinces are also discussed, revealing that this island's mollusk fauna is a blend of warm-temperate and subtropical-tropical species.

• 한국수산과학회지
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• 제25권3호
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• pp.171-175
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• 1992

피조개의 핵형을 구명할 목적으로, 1991년 여름 경상남도 남해산을 온도자극법에 의해 인위적으로 방난방정을 유발하였다. 1. 발생중인 Trochophore 유생을 사용하여 공기건조법에 의해 다수의 명료한 중기분열상을 관찰할 수 있었다. 2. 피조개의 염색체는 2n=38로서, 핵형은 3쌍의 중부동원체형, 2쌍의 중부-차중부동원체형, 10쌍의 차중부동원체형과 4잡의 차단부동원체형으로 구성되었음이 확인되었다.

• 한국해양생명과학회지
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• 제9권1호
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• pp.41-46
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• 2024

This study aimed to reconfirm the sex change scale and pattern of Tegillarca granosa. Although the sex ratio (female : male, female proportion) of T. granosa was 1:2.32 (30.2%) at the initial stage (2011) of the study, it was 1:0.94 (51.5%) after one year (2012) in the same population. The increase of the female proportion was greater in the 2+ year class (23.0%) when compared to the 1+ year class (19.2%). Overall, sex change ratio of 37.6% was observed in this population of T. granosa. The sex change ratio of the 2+ year class (39.3%) was higher than that of the 1+ year class (35.3%). And sex change ratio in the males (42.2%) was higher than that in the females (26.9%). The female proportion was the opposite of the result from 2006~2007, and one of the causes was presumed to be the difference in cumulative water temperature during the gonadal inactive stage (winter).

• 한국양식학회지
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• 제21권4호
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• pp.252-258
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• 2008

전라남도 여수시 소라면 여자만에서 2007년 3월부터 2008년 2월까지 채집된 새꼬막 Scapharca subcrenata의 생식소 발달과 생식주기를 조직학적으로 조사하였다. 새꼬막은 자웅이체로 난소는 많은 난소 소낭(oogenic follicle)으로 이루어져 있으며, 정소도 많은 정소 소낭(acinus)으로 구성되어 있다. 생식소지수(GI)는 6월에 연중 최고 값을 나타내었고, 그 후 감소하여 7월에 최저 값를 나타내었다. 비만도지수(CI)는 4월에 연중 최고 값을 보였고, 그 후 감소하여 7월에 최저 값을 보였다. 새꼬막의 생식주기는 초기 활성기($1{\sim}4$월), 후기 활성기($3{\sim}6$월), 완숙기($5{\sim}8$월), 방출기($7{\sim}9$월) 그리고 회복 및 휴지기($9{\sim}3$월)의 연속적인 발달 단계로 구분되었으며, 주 산란기는 $7{\sim}8$월로 조사되었다. 암, 수 성비는 1:1로 유의한 차를 보이지 않았다.

• 한국패류학회지
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• 제31권4호
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• pp.315-322
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• 2015

이매패류의 성은 자웅이체와 자웅동체로 구분되며, 자웅이체는 동시자웅동체와 비동시자웅동체로 나누어진다. 비동시자웅동체는 계절에 따른 성의 전환을 의미한다. 일반적으로 자웅이체 이매패류의 경우 형태학적 성으로 표현되는 암, 수는 개체의 생활사 가운데 일정한 한 시기에 국한된 것이다. 개체의 성을 정확히 확인하기 위해서는 성을 표지한 후, 생활사 동안 성의 변화를 연속적으로 추적해야 한다. 이매패류에서 성전환과 비동시자웅동체는 굴과, 가리비과, 백합과 및 돌조개과 등의 이매패류에서 보고되고 있다. 이들 연구의 대부분은 동일 개체군에서 연령에 따른 성비의 변화를 증거로 이러한 결론에 도달하게 되었다. 비동시자웅동체 이매패류에서 성의 변화는 보통 방란, 방정 후 생식소의 비활성기에 일어난다. 이매패류에서 성결정과 성의 변화에는 유전적 요인과 환경적 요인 두 가지가 관여하지만, 이에 관한 이들의 영향에 관해서는 세부적인 연구가 필요하다.

• 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.