• 한국패류학회지
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• 제25권1호
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• pp.15-22
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• 2009

Because it is known that bivalve hearts contain various modulatory systems activated by neuroendocrine substances, it was examined whether different classes of endogenous and synthetic drugs of neuroendocrinological importance can influence cardiac functions of the Pacific oyster Crassostrea gigas. Cholinergically active agents acetylcholine and carbachol increased heart rates while diminishing cardiac contractility. Adrenergically active substances norepinephrine (NE) and epinephrine (Epi) also induced heart rate increase and contractility decrease. An $\alpha_1$-adrenergic receptor-selective agonist phenyephrine (PE) failed to modulate either parameter. The Epi-induced heart rate increase and contractile depression were both blocked significantly by non-selective $\beta_1/\beta_2$-adrenergic antagonist propranolol. A $\beta_1$-selective antagonist atenolol prevented Epi-induced heart rate decrease but not the contractile depression, suggesting possible $\beta_2$ receptors for Epi-induced contractile depression. The three autacoids examined exerted discrete responses: histamine increased heart rate and depressed contraction; $\gamma$-amino-butyric acid increased both parameters; serotonin failed to change either parameter. The 5 piscine anesthetic agents examined, MS-222, benzocaine, quinaldine, urethane, pantocaine and pentobarbital, all failed to influence the cardiac function of oysters. Collectively, activities of neuroendocrinologically acting agents in mammals showed unexpected and distinct activities from those in mammalian cardiovascular systems. These results obtained from substances of different physiological functions can serve as a basis for understanding neuroendocrine control of the heart function in Pacific oyster.

• 한국패류학회지
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• 제32권2호
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• pp.67-71
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• 2016

굴의 종패생산 시 수정란을 대량으로 얻기 위하여 성숙한 굴 어미를 대상으로 신경전달 물질인 serotonin의 최적 처리 농도를 파악하기 위한 연구가 수행되었다. Serotonin 주사 후 방란까지 소요되는 시간은 7.6분부터 27분까지 였으며, 농도가 낮아짐에 따라 소요시간은 유의하게 길어졌다 (P < 0.05). 방정시간 역시 방란시간과 비슷한 경향을 보였다. Serotonin 농도에 따른 반응률 역시 처리 농도가 높을수록 반응률이 높아졌다. Serotonin 처리 후 산란량을 조사한 결과, $10^{-2}M$ 에서 2,664천개로 $10^{-5}M$ 농도에 비해 유의하게 많았으나 (P < 0.05), $10^{-4}$나 $10^{-3}M$ 처리구는 유의한 차이를 나타내지 않았다 (P > 0.05). Serotonin 처리 후 산란된 알의 GVBD율, 수정률 및 부화율은 농도에 영향을 받지 않았다.

• 환경생물
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• 제27권3호
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• pp.279-284
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• 2009

In order to understand food sources-metabolism for the pacific oyster (Crassostrea gigas), the stable isotope ratios of carbon (${\delta}^{13}C$) and nitrogen (${\delta}^{15}N$) of its gut, gill, and muscle as well as potential food sources (particulate organic matter, sedimentary organic matter, benthic microalgae, seagrass detritus) were determined in Dongdae Bay. Average ${\delta}^{13}C$ and ${\delta}^{15}N$ values reflect that oysters primarily fed on sedimentary organic matter as opposed to suspended organic matter during summer and winter seasons. However, the relatively enriched $^{15}N$ values of particulate organic matter (>$250{\mu}m$) and sedimentary organic matter in the summer may be due to the photosynthetic incorporation of $^{15}N$-enriched nitrogen (DIN) or the spawning events of bivalves. Specific oyster tissues (gut, gill, and muscle) revealed different metabolic pathways, which were determined through analysis of ${\delta}^{13}C$ and ${\delta}^{15}N$ in each organ. The present results suggest the determination of carbon and nitrogen stable isotopes to be a useful approach in ecological research related to the food sources- metabolism of Crassostrea gigas.

• 한국수산과학회지
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• 제43권5호
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• pp.489-494
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• 2010

The nutritional demand of oyster larva (Crassostrea gigas) were investigated to determine the optimal culture conditions and improve micro-algae utilization. Changes in nutrients and shell growth were examined in fed and 96-h (48 h in late umbone stage) oysters at four larval stages. Shell growth increased significantly in D shape larvae, regardless of feeding variations. No growth was observed in starved larvae, except in shell length of umbone (to 11.9 ${\mu}m$). Fed larvae showed significant growth in all development stages (P < 0.05). During starvation, lipids were most significantly decreased in all larval stages (by 76.8%, 68.3%, 76.3%, and 40.3%, respectively), followed by protein (41.1%, 31.1%, 33.1%, 16.7%) and nitrogen-free extracts (40.8%, 24.3%, 36.9%, 20.1%), Gross energy (kcal/g) consumption in each larval stage was 49.6%, 35.1%, 39.1%, and 20.4%, respectively. Our results indicate that lipids are the most important energy source during the early larval development stages of C. gigas.

• 한국양식학회지
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• 제20권4호
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• pp.205-211
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• 2007

Stress-inducible proteins may function in part as molecular chaperones, protecting cells from damage due to various stresses and helping to maintain homeostasis. We examined the mRNA expression patterns of a 68-kDa heat shock protein (HSP68) and 78-kDa glucose-regulated protein (GRP78) in relation to physiological changes in Pacific oyster Crassostrea gigas under osmotic stress. Expression of HSP68 and GRP78 mRNA in the gill significantly increased until 48 h in a hypersaline environment (HRE) and 72 h in a hyposaline environment (HOE), and then decreased. Osmolality and the concentrations of $Na^+$, $Cl^-$, and $Ca^{2+}$ in the hemolymph of HRE oysters significantly increased until 72 h (the highest value) and then gradually decreased; in HOE oysters, these values significantly decreased until 72 h (the lowest value), and then increased. These results suggest that osmolality and $Na^+$, $Cl^-$, and $Ca^{2+}$ concentrations were stabilized by HSP68 and GRP78, and indicate that these two stress-induced proteins play an important role in regulating the metabolism and protecting the cells of the Pacific oysters exposed to salinity changes.

• 한국해양환경ㆍ에너지학회지
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• 제16권2호
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• pp.138-142
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• 2013

저염분에 따른 양식생물의 피해를 줄이기 위한 조기경보 방안으로 염분에 따른 굴(Crassostrea gigas) 패각운동 특성을 홀 소자를 이용하여 측정하는 생물모니터링시스템의 적용 가능성을 조사하였다. 염분농도 27 psu에서 굴의 패각운동은 평균 10-15 mm 정도의 개각상태를 유지하다가, 비교적 빠른 폐각상태를 지시하는 큰 파형이 보였으며, 다시 개각상태로 돌아가나, 그 속도는 폐각상태로 진행되는 속도보다 느리게 나타났다. 20 psu까지 저염분의 농도에서는 27 psu의 패각 운동과 큰 변화가 없었다. 하지만 17 psu 이하의 염분농도부터 이상 패각운동이 지시되었으며, 10 psu에서는 패각운동이 없이 폐각상태를 유지하였다. 이와 같은 생물모니터링시스템을 패류 양식에 활용하여 해양환경의 이상변동을 신속히 감지할 수 있다면, 어업피해를 감소시킬 활동으로 연결될 것으로 기대된다.

• 한국어병학회지
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• 제14권2호
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• pp.103-105
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• 2001

The effect of opsonization of zymosan with serum on the repiratory burst of haemocytes isolated from the Pacific oyster Crassostrea gigas was investigated. The reactive oxygen species (ROS) produced by the respiratory burst of haemocytes in response to the opsonized or unopsonized zymosan were measured using chemiluminescence (CL). The CL values were increased according to the increment of haemocyte number. The degree of CL amplification by increase of haemocytes from $0.1{\times}10^6$ to $0.5{\times}10^6$ cells/ml was 3-5 times, but comparatively low amplification was elicited by increase of haemocytes from $0.5{\times}10^6$ to $1{\times}10^6$ cells/ml. Chemiluminescences produced by the haemocytes in response to the zymosan opsonized with oyster serum were considerably higher than the CL produced by the haemocytes in response to the unopsonized zymosan.

• 한국수산과학회지
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• 제54권4호
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• pp.434-444
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• 2021

The decrease in fatness of the Pacific oyster Crassostrea gigas, which consequently results in decrease in the profit of aquaculture industry, has become a source of serious concern in southeast coast of Korea. The ratio of flesh (edible portion) to total oyster weight, commonly called edible portion yield ("suyul" in Korean), have been used as a fatness index for the healthy and valuable state of oyster from the early stage of oyster farming in Korea. More than 360 data sets were collected from early culturing periods (in the 1970s) to the present from approximately 15 published literatures to evaluate the long-term fatness trend of oyster, reared particularly in submerged longline culturing system in Gyeongsangnam-do province. Slight decrease in oyster fatness during the 1970s to 1990s was detected in Tongyeong and Geoje Bays; however, from the 1990s to the present, clear decreasing trends were observed with a decrease of 0.04-0.08% year^-1, especially during harvest season. Oyster mass production per unit area almost doubled within a short period in the early 2000s; however, changes in coastal environment factors inhibited the fattening of shellfish from the mid 1990s. These results indicate that the severe competition in feeding and low biological production in water column might be some convincing reasons for the decrease in fatness of oyster from the 1990s, in Tongyeong and Geoje Bays, Korea.

• Fisheries and Aquatic Sciences
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• 제5권3호
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• pp.191-199
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• 2002

Pacific oysters Crassostrea gigas (Thunberg) were collected on April, 1999 and March­September, 2000 from Goseung Bay along the southern coast of Korea. The oysters tested cp;;ected from a depth of 0.5-2 m in which they cultured by a long line hanging method. The oxygen consumption rates (OCR) of oysters held under constant temperature and darkness (CC), were determined using an automatic intermittent-flow-respirometer (AIFR). Depending on holding periods after oyster collection, the experiments were divided into two groups: Group 7-d (held to ambient temperature for ca. 7 days) and Group 2l-d (held to ambient temperature for ca. 21 days). The OCR for Group 7-d single oyster displayed two peaks every day under CC, while Group 2l-d single oyster showed one peak every day. It is likely that the rhythmic patterns 02.6-12.8 hours) of the OCR in the Group 7-d single oyster may have been influenced by tidal currents at the sampling site. The rhythmic patterns (24.3-24.7 hours) in the Group 2l-d single oyster may have been shifted from two peaks to one peak each day under CC. The present study concludes that the OCR rhythm of wild oysters in nature is governed by two lunar-day clocks (24.8 hours); one driving one peak and the other driving the second peak. When oysters are subjected to the long-term CC conditions, one of the two-clock systems is depressed or only intermittently becomes active. Jpwever. the OCR rhythms by two to three oysters occurred arrhythmic patterns during the experiments and exhibited some evidence of weak rhythmicity of compared to those of a single oyster. It could be partly due to differences group effects.

• 한국산학기술학회논문지
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• 제18권11호
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• pp.778-784
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• 2017

참굴(Crassostrea gigas)의 패각운동을 이용하여 Alexandrium 속의 조기 출현모니터링 가능성을 고찰하였다. 지구규모에서 패류독화를 발생시키는 A. fundyense와 잠재적 유독종으로 알려진 A. affine를 이용하여 홀 소자센서(Hall element sensor)를 사용하여 참굴의 패각운동(SVMs)을 측정하였다. 참굴은 Isocrysis galbana를 먹이생물로 하여 안정화 시킨 다음 3일간 절식 시킨 후 실험에 제공하였다. 결과 참굴은 A. fundyense에 대해 세포밀도 20 cells/mL에서 SVMs 횟수가 $10.5{\pm}1.2times/hr$로 증가하여 민감하게 반응하였고, 세포밀도 500 cells/mL에서 재차 $14.1{\pm}5.7times/h$, 5,000 cells/mL에서 $27.9{\pm}11.1times/hr$로 SVMs가 급격한 증가를 보였다. 그러나 A. affine에 대해서는 세포밀도가 300 cells/mL까지 $6.7{\pm}3.9times/hr$로 기준 SVMs와 유사하였고, 세포밀도 1,000 cells/mL 이상에서 $15.3{\pm}10.8times/hr$로 급격히 증가하였다. 즉 A. fundyense는 20 cells/mL에서부터 참굴의 SVMs가 민감하게 반응하였지만, A. affine는 높은 1,000 cells/mL의 세포밀도에서 SVMs가 반응하였다. 이러한 결과에서 유독와편모조에 대한 참굴의 SVMs는 종에 따른 차이가 있어, A. fundyense의 초기발생 예보에는 유용하게 활용 가능하지만, A. affine에 응용하는 것은 어렵다는 결론을 얻었다.