• 한국패류학회지
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• 제31권3호
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• pp.179-186
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• 2015

굴 미수정란의 동결보존에 적합한 동해방지제의 종류, 농도 및 침투 시간을 구명하기 위하여 4가지 동해방지제 (DMSO, EG, methanol, PEG) 를 대상으로 수정률, 부화율 및 형태 이상률을 조사하였다. 동해방지제의 농도 및 침지시간은 각각 5, 10, 15, 20%와 10, 20, 30, 40분이었다. 침지 후 미수정란은 정상 정자와 수정되었고, 수정률, 부화율 및 형태 이상률은 동해방지제의 종류와 농도 및 침지시간에 영향을 받았다. 동해방지제의 농도와 침지시간의 증가에 따라 수정률과 부화율은 낮아졌고, 대부분의 동해방지제에서 5-10% 농도와 10-20분의 짧은 침지시간에서 좋은 결과를 보였다. 수정률과 부화율을 근거로 굴 미수정란에 가장 적합한 동해방지제는 DMSO였으며, 처리 농도와 침지 시간은 각각 5%와 10-20분이었다.

• 한국수산과학회지
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• 제49권3호
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• pp.351-358
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• 2016

The aim of this study was to verify the performance of Teleaulax amphioxeia as prey for Brachionus plicatilis and for the larvae of the bivalves (Pacific oyster Crassostrea gigas and Manila clam Ruditapes philippinarum) to select the best of five T. amphioxeia strains. The five strains of T. amphioxeia were collected from the coasts of Korea, purecultured and then fed to the rotifer and bivalve larvae. The density and fecundity rate of the rotifer fed on strain 01 were the highest. The instantaneous growth rate of the rotifer fed strain 08-2 was the highest. The maximum density and fecundity rate of the rotifer fed strain 08-2 were significantly higher than those fed Chlorella ellipsoidea, while instantaneous growth rate showed the opposite pattern. Survival rates of the Manila clam larvae fed each strain of Teleaulax showed no significant difference between strains. Survival rates of the Pacific oyster fed Teleaulax were significantly higher than those fed Chaetoceros sp., but lower than those fed I. galbana. This study indicates that strain 08-2 showed better growth for B. plicatilis and better survival for the bivalve larvae than did the other strains, and that T. amphioxeia can also be used as a prey organism for rotifers or bivalve larvae.

• Parasites, Hosts and Diseases
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• 제49권3호
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• pp.229-234
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• 2011

In order to assess changes in the activity of immunecompetency present in Crassostrea gigas infected with Marteilioides chungmuensis (Protozoa), the total hemocyte counts (THC), hemocyte populations, hemocyte viability, and phagocytosis rate were measured in oysters using flow cytometry. THC were increased significantly in oysters infected with M. chungmuensis relative to the healthy appearing oysters (HAO) (P<0.05). Among the total hemocyte composition, granulocyte levels were significantly increased in infected oysters as compared with HAO (P<0.05). In addition, the hyalinocyte was reduced significantly (P<0.05). The hemocyte viability did not differ between infected oysters and HAO. However, the phagocytosis rate was significantly higher in infected oysters relative to HAO (P<0.05). The measurement of alterations in the activity of immunecompetency in oysters, which was conducted via flow cytometry in this study, might be a useful biomarker of the defense system for evaluating the effects of ovarian parasites of C. gigas.

• 한국수산과학회지
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• 제30권1호
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• pp.72-78
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• 1997

패류 건제품중에 생성되는 향기성분의 주요한 전구체로 알려져 있는 환원당, 유기산 및 지방산의 거동을 살펴보기 위하여 홍합, 바지락 및 굴의 건제품 가공중의 성분조성과 함량의 변화를 조사하였다. 유리환원당의 함량은 자숙후에 큰 감소를 보였으며 홍합과 바지락의 경우에는 건조후에도 크게 감소하였다. 홍합, 바지락 및 굴 에서는 각각 8종의 유기산이 분석되었는데 함량이 높은 유기산은 succinic acid로써 총유기산량의 $74.9\%,\;67.4\%,\;38.4\%$를 차지하였고 특히 굴에서는 pyroglutamic acid의 함량이 $41.6\%$로써 가장높았다. 천일건조 및 열풍건조 후에는 succinic acid 이외의 다른 유기산들의 함량은 급격히 감소하였는데, 굴의 건제품에서는 $53.0\%$와 $44.2\%$의 큰 감소를 보인 반면 바지락의 건제품에서는 $29.0\%$와 $10.0\%$로써 비교적 감소량이 적었다. 지질 성분의 분석결과에서는 극성지질의 함량이 총지질함량의 $59.1\%,\;66.7\%,\;42.4\%$의 높은 값을 보였으며 주요 구성지방산은 C16 : 0, C16 : 1, C20 : 5, C22 : 6등이었고 폴리엔산이 각각 $40.51\%,\;48.6\%,\;48.77\%$의 높은 조성비를 나타내었다. 각 시료의 자건제품의 과산화물가는 $41.64\~86.80\;meq/kg$으로써 비교적 높았고 카아보닐가는 $15.55\~27.99\;meq/kg$으로써 났았으나 배건제품중의 카아보닐가는 $127.6\~136.5\;meq/kg$의 높은 값을 나타내었다.

• 한국수산과학회지
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• 제8권2호
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• pp.90-100
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• 1975

로우푸수하식 양식굴의 가공적성에 관한 실험을 하여 다음과 같은 결과를 얻었다. 1. 굴의 각내부피에 대한 연체부의 무게 또는 각내 부피에 대한 연체부의 부피의 측정값으로서 비만도를 측정하는 지표로 이용할 수 있다. 2. 육류분의 월별변화를 보면 수분과 지방은 대체로 역상관관계가 됐고, 단백질은 4월부터 약간감소하기 시작하여 7월에 급격히 감소하였다가 8월에 다시 급격하게 증가하나 9월부터 다시 점차 감소하는 경향을 나타내었다. 글리코겐은 4월부터 급격하게 감소하기 시작하여, $6\~8$월에 최저값을 나타내고, 9월부터 다시 증가하였다. pH는 $6.0\~6.2$로서 시간적으로 큰 변화는 찾아 볼 수 없이 거의 일정하였다. 회분은 $6\~8$월에 약간 감소하는 경향이 있었다. 3. 비만도 및 육성분 분석결과로써 가공적성을 판정한다면 가공원료 채취적기는 12월말에서 다음에 5월까지라고 보아진다. 4. 중금속함량의 시기적변화범위를 보면 수은은 $0\~0.019ppm$, 카드뮴은 $0.026\~0.053ppm $, 구리는 $0.111\~0.594ppm$ 남은 $0.061\~0.581ppm로 $로서 가공원료로 안전하다고 볼 수 있다. 5. 생굴을 냉동하기 전에 플리인산나트륨을 $10\%$ 함유한 $5\%$ 식염수에 침지처리한 것은 해동시에 drip 유출방지핵과가 있었다. 6. $ Na_2EDTA$또는 BHA용액에서 침지처리하는 전처리 조작만으로서는 굴 보일드통조림의 황변을 방지할 수 없었다. 7. $2\%$염화마구네슘 용액은 살아 있는 굴의 개각활동을 촉진하는 효과가 있었다.

• 한국패류학회지
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• 제29권3호
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• pp.245-250
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• 2013

We investigated the factors of mass-mortality in terms of water temperature and prey, in order to prevent the mass-mortality of cultured oysters at Gamak Bay in Yeosu City in 2007. The real-time water temperature was recorded as high, 28 to 31C, during late August. Nutrients, Dissolved Inorganic Nitrogen (DIN) and Dissolved Inorganic Phosphate (DIP) were downed in September. The analyzed results of chlorophyll a content were 0.78-1.50 ${\mu}gL^{-1}$ and phytoplankton for food resources was 81 cells $mL^{-1}$, both were low. The finding here indicate that Gamak Bay is in an oligotrophic state. The mass-mortality of cultured oysters occurred 43.6% in Gamak Bay. The mortality rate of oyster were above 67.0%, at Wanpo, however, it was showed 18.3% at Gumchun. Therefore, we believe the mass-mortality of cultured oysters at Gamak Bay comes from the destruction of bio-rhythms due to high water temperature and quantitatively and qualitatively decreasing food resources due to the limitation of nutrients.

• 한국패류학회지
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• 제29권3호
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• pp.217-223
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• 2013

The morphological relations and physiological characteristics of the triploid and diploid oysters (Crassostrea gigas) in Taean area, west coast of Korea, were investigated from May 2012 to April 2013. Mophometric analysis indicated that the triploid oysters have the same shell length to shell height ratio but higher shell depth to shell height ratio than diploids. Consistent with morphological characteristics, triploid oysters showed greater values of fatness, condition index and RNA/DNA ratio during the period of experiment. The DNA concentration in adductor muscle and mantle of triploid were either lower or equal to the nucleic acids of diploid. However, RNA/DNA ratio were significantly higher than diploid. It appears that RNA/DNA ratio could be a useful indicator of health condition of triploid and diploid oysters when taken in correlation with the morphological indices.

• 한국수산과학회지
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• 제50권5호
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• pp.500-505
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• 2017

The nucleotides and their related compounds, including ATP (adenosine triphosphate), ADP (adenosine diphosphate), AMP (adenosine monophosphate), IMP (inosine monophosphate), HxR (inosine) and Hx (hypoxanthine), were nearly identical in oysters Crassostrea gigas from the two culture methods. The K-value was lower than the threshold value such as 11.2-12.1. Although oysters have low amount of IMP, it was detected in this experiment. DPPH radical scavenging activity did not vary significantly with sample amounts (100, 300, and $500{\mu}g/mL$). DPPH (1,1-diphenyl-2-picryl-hydrazyl) radical scavenging activity was 76.0-80.7% compare with the ascorbic acid standard. Superoxide anion scavenging activity reached 49.3% in the rack-and-bag culture sample at $500{\mu}g/mL$. However, the reducing power and $Fe^{2+}$ chelating activity were very low compared with their respective standard. The oyster culture methods did not affect oyster quality in terms of antioxidant activities.

• 한국수산과학회지
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• 제50권3호
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• pp.263-269
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• 2017

The mineral contents, and free amino acid, and fatty acid composition of rack and bag or suspended cultured oysters Crassostrea gigas were compared. The moisture content did not change much from 82.8% to 86.3% in the different culture methods. The glycogen level was low 4.7% during rack and bag culture but high 7.2% during suspended culture. The sodium level was the highest during suspended culture, while copper and zinc level were highest during rack and bag culture. The taurine level was 1,385-1,375 mg/100 g in oyster cultured using the rack and bag method, but that in the market sample was lowest at 1,015.8 mg/100 g. Hydroxyproline, glutamic acid, proline, glycine, and alanine were detected at high levels in the experimental oysters. The polyunsaturated fatty acid content was similar among samples. The docosahexaenoic acid level was 14% with rack and bag culture and 12% with suspended culture, whereas the eicosapentaenoic acid level was 15% with rack and bag culture and 20% with suspended culture. The atherogenic index (AI), thrombogenicity index (TI), and hypocholesterolemic/ hypercholesterolemic (h/H) ratio were important factors in the nutritional evaluation. The AI and TI values were 0.5-0.2, and the h/H ratio were 2.0 and 2.4 with the rack and bag and suspended culture, respectively.

• 한국패류학회지
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• 제21권1호
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• pp.33-40
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• 2005

Occurrence and prevalence of Marteilioides chungmueasis have been reported in several waters around Tongyeong but no report has been made for Pukman bay. Therefore, we investigated that the prevalence and infection intensities in Pukman Bay at the inside and the outside areas which are hydrographically divided by tidal current. Furthermore, various environmental parameters were investigated in order to elucidate effective parameter for parasitic infection. Infection rates of Marteilioides chungmuensis in adult oysters were ranged 3.3-20.0% at the inside area during September 2002 through January 2003, and 3.3-30.9% at the outside area during August 2002 through January 2003. External manifestation of infected oyster consisted of abnormal egg masses with nodular appearance in the soft tissue. Histopathological symptoms included massive hemocytic infiltration within or around the follicle wall and atrophic epithelium of digestive diverticula. For the environmental parameters, comparative study made differences between two side of the Bay during the infection period: inside > outside for SS while inside < outside for chlorophyll-a. A positive relationship was observed between chlorophyll-a and infection period, which might indicate the difference in food availability between two areas. The prevalence of ovarian parasite Marteilioides chungmuensis, therefore, was highly associated with food availability. Pearson's correlation analysis was made between environmental parameters and infection prevalence. Significance was observed in water temperature (p < 0.05), suspended solids (p < 0.01) and chlorophyll-a (p < 0.05). A principle component analysis showed that infection of the ovarian parasite, Marteilioides chungmuensis, exhibited effects of seasonality (component I = 55.2%) and chemical/physical environmental factors (component II = 24.4%). These results clearly indicate that the infection of ovarian parasite, M. chungmuensis in the Pacific oyster Crassostrea gigas is closely associated with seasonality and food availability.