• 한국패류학회지
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• 제31권4호
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• pp.267-272
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• 2015

This study was conducted in order to elucidate the dissemination mechanism of P. olseni using field and laboratory experiments. For this purpose, we quantified the level of P. olseni infection in buried (healthy) and surfaced (gapped) R. philippinarum from a clam bed on Wi-do Island on the west coast of Korea. In addition, the levels of internal and released P. olseni cells from artificially infected (and later dead) R. philippinarum were monitored for 8 days using the RFTM-2 M NaOH lysis method. Our results indicate that P. olseni cells in buried R. philippinarum was $2,655,625{\pm}1,536,936cells/clam$; the level in gapped R. philippinarum was considerably lower, $28,203{\pm}24,889cells/clam$ (p < 0.05). In the laboratory experiment, the P. olseni cells remained in the host tissue 2 days after death was approximately 50% lower than the level of infection measured in living clams. The level dropped to 20% 4 days after death and to 1.5% 6 days after death; eight days after death, P. olseni cells were undetectable since the R. philippinarum flesh had completely decomposed. The level of released cells on the day of death was only 0.05% of the internal level in live R. philippinarum; however, the level increased to 2.3% 5 days after death then gradually decreased and no released cells were detected 8 days after death. Therefore, our laboratory experiment suggest that the low level of P. olseni infection observed in gapped R. philippinarum at Wi-do Island could be caused by lysis of the most of P. olseni cells during the decomposition of dead R. philippinarum tissues. Until the end of decomposition of R. philippinarum, 6.68% of the total amount of P. olseni was released within 8 days. Our study showed that the amount of P. olseni cells from dead host is a considerably higher level than naturally released from healthy R. philippinarum, suggesting that death of the host plays an important role in the dissemination of P. olseni.

• 한국발생생물학회지:발생과생식
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• 제16권3호
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• pp.177-183
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• 2012

This study attempts to propose the possibility of the sex reversal in Tegillarca granosa and Ruditapes philippinarum by confirming the changes in the sex ratio with the shell length (SL) in the same population level. For analysis of sex ratio with SL, 1500 individuals of T. granosa (SL 10.1-45.0 mm) and 712 individuals of R. philippinarum (SL 15.1-70.0 mm) were used. Sex was analyzed histologically. The average sex ratios (F:M) of T. granosa and R. philippinarum were 1:1.22 and 1:0.96, respectively. However, sex ratio was found to differ when the clams were divided into groups according to SL in 5.0 mm intervals. Both species displayed the tendency of increase in the proportion of female with increase in SL. In this study, changes in the sex ratio in accordance with the growth of T. granosa and R. philippinarum are determined to be indirect evidence that signifies their sex reversal.

• 한국패류학회지
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• 제28권1호
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• pp.29-35
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• 2012

Growth patterns of the Manila clam, Ruditapes philippinarum in each tidal level were studied in the intertidal zone in Tae-an on the west coast of South Korea from April to August 2009. Environmental factors and the specimens of R. philippinarum were monthly collected at three intertidal locations: low intertidal zone, low-middle intertidal zone and middle intertidal zone. Temperature of sediment in low intertidal zone were lower than those in other intertidal locations. Concentrations of Chl-${\alpha}$ were not significantly different between in each tidal level. Exposure hours in low intertidal zone were shorter than those in other intertidal locations. Density of each year class in low intertidal zone were higher than those in low-middle intertidal zone and middle intertidal zone. Growth factors of R. philippinarum in low intertidal zone were better than those in other intertidal locations. The growth rate of under one year class individuals of low intertidal zone were higher than those in low-middle intertidal zone and middle intertidal zone, before the main recruitment period of R. pilippinarum. Although the growth patterns of R. philippinarum may be affected by various environmental factors, we suggests that the exposure duration is the main affect in the growth patterns of R. philippinarum in intertidal zone.

• 한국수산과학회지
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• 제34권3호
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• pp.190-193
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• 2001

바지락의 용존산소 농도에 따른 SFG (Scope for growth)의 변화를 알아보기 위하여 수온 $23\pm0.5^{\circ}C$와 일반해수에서 반수치사농도, 여수율, 호흡률, 암모니아 질소배설률 및 동화효율 등을 측정하였다. 바지락의 용존산소 농도의 감소에 따른 $LC_{50}$은 2.4mgDO$L^{-1}$였다. 여수율과 호흡률은 실험용액의 용존산소의 감소에 따라 대체로 감소하는 경향을 보인 반면, 암모니아 질소 배설률은 용존산소의 감소에 따라 증가하였다. 동화효율은 6.5mgDO $L^{-1}$에서는 $68.2\%$였으며, 3.5 mgDO $L^{-1}$ 이하의 농도에서는$29.8\~39.3\%$로 차이를 나타내지 않았다. 용존산소의 농도에 따른 SFG는 2.5mgDO $L^{-1}$ 이상에서는 양의 값을 나타내어 생존 및 성장이 가능한 것으로 나타났다.

• 한국패류학회지
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• 제24권1호
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• pp.25-32
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• 2008

In order to estimate the necessity of refrigerated storage of fresh seafood for short-term storage, and evaluate the effect of refrigerated storage on pen shell Atrina pectinata and clam Ruditapes philippinarum collected from Jang-su of Deukryang Bay and I-mok of Sunchen Bay in South Korea, the counts of coliform, Escherichia coli and total aerobic bacteria in A. pectinata and R. philippinarum under non-refrigerated $(28{\pm}1^{\circ}C)$ and refrigerated storage conditions $(4{\pm}1^{\circ}C)$ were determined. The results indicated that the storage at temperature of $4^{\circ}C$ possessed significant effects on inhibiting bacterial growth in live seafood. And refrigerated storage had different effect on A. pectinata and R. philippinarum. Different species and culture environments significantly influenced the initial and ultima bacteria counts. This study confirmed that refrigerated storage for short-term storage of live seafood was necessary, and indicated that the effect of refrigerated storage was influenced by comprehensive effectors.

• Parasites, Hosts and Diseases
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• 제55권4호
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• pp.399-408
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• 2017

A survey was performed to know the recent infection status of digenetic trematode metacercariae in clams and oysters from 4 sites in western coastal regions of the Republic of Korea (=Korea). Four species of clams (Mactra veneriformis, Ruditapes philippinarum, Cyclina sinensis, and Saxidomus purpuratus) were collected from Taean-gun, Chungcheongnam-do (Province), Buan-gun (County) and Gochang-gun, Jeollabuk-do, and oysters, Crassostrea gigas, from Shinan-gun, Jeollanam-do were transferred to our laboratory on ice and examined by the artificial digestion method. The metacercariae of Himasthla alincia were detected in 3 species of clams, M. veneriformis, R. philippinarum, and C. sinensis from the 3 surveyed areas. The positive rate and the mean density per clam infected were 98.9% (30.8 metacercariae) in M. veneriformis, 60.0% (5.0) in R. philippinarum, and 96.0% (28.4) in C. sinensis. The positive rate (mean density) of Acanthoparyphium tyosenense metacercariae in M. veneriformis was 50.0% (2.1) from Taean-gun and 70.0% (2.8) from Gochang-gun. The metacercariae of Parvatrema spp. were detected in M. veneriformis and R. philippinarum from Taean-gun and Gochang-gun; the positive rate (mean density) was 63.3% (4,123) and 50.0% (19) in M. veneriformis, and 6.7% (126) and 100% (238) in R. philippinarum from the 2 regions, respectively. The metacercariae of Gymnophalloides seoi were detected in all 30 oysters from Shinan-gun, and their average density per oyster was 646. From the above results, it has been confirmed that more than 3 species of metacercariae are prevalent in clams from the western coastal regions, and G. seoi metacercariae are still prevalent in oysters from Shinan-gun, Jeollanam-do, Korea.

• 한국수산과학회지
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• 제2권2호
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• pp.155-160
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• 1969

본 연구는 바지락(Tapes Philippinarum) 서식지의 토양을 물리화학적 방법으로 토성, 구성성분 및 유핵화학성분을 분석하여 본종의 서식밀도와의 관계를 조사하여 바지락서식의 적지요인을 연구하였다. 1. 각력의 조성률은 바지락의 서식밀도와 정상관(r=0.78) 관계가 있으며 $13.5\%$ 이상이 적당하다. 2. 조사의 조성률은 바지락의 서식밀도와 정상관(r=0.73) 관계가 있으며 $23.0\%$ 이상의 함량이 적당하다. 3. 세사의 함양은 바지락의 서식밀도와 정상관(r=-0.42)의 관계가 있으며 $41.5\%$ 이하가 적당하다. 4. 징사의 함량은 바지락의 서식밀도와 정상관(r=-0.68)의 관계가 있으며 $10.0\%$ 이하가 적당하다. 5. 점토분은 바지락의 서식 밀도와 부상관(r=-0.51)의 관계가 있는 것으로 $6.8\%$ 이하의 저토가 적당하다. 6. 바지락 서식지의 간석토는 규반율이 $5.09\~5.60$으로 규산질의 초토이다. 7. 바지락 서식지의 토양 pH, 보수능, 유기물, 총질소, 유효린산, 치환성 Ca, 및 치환성 Mg의 함양은 각각 $6.15\~6.60,\;4.26\~6.86\%,\;0.40\~1.10\%,\;14.0\~27.0ppm,\;0.041\~0.394\%$, 및 $0.009\~0.132\%$이었다.

• 한국양식학회지
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• 제10권3호
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• pp.227-237
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• 1997

Five species of intertidal clams including Ruditapes philippinarum, Tegillarca granosa, Solen strictus, Heteromacoma irus, and Coecella chinensis were tested for the presence of the protozoan parasite, Perkinsus sp. using fluid thioglycollate medium (FTM) fortified with antibiotics and histological techniques. Each individual clam was placed in a test tube filled with 10ml FTM, placed in totally dark place, and incubated over a week. After incubation the clam tissues were stained with Lugol's iodine solution and examined under a light microscope to find out any hypnospores of Perkensus sp. in the tissues. Cross-sections of the clams were also embedded in paraffin, sliced to 3um, and stained with Harry's hematoxylene and Picro eosine to observe the presence of tomont or trophozoites. Perkinsus sp. were found in the presence of tomont or trophozoites. Perkinsus sp. were found in the tissues of R. philippinarum collected from Kangjin and Wando, along the south coast of Korea. However, Perkinsus sp. was not found in four other species of clams nor R. philippinaurm collected from Kimnyong and Waido in Cheju. A size-dependent Perkinsus sp. infection was found in R. philippinarum collected rom Kangjin and Wando the clams smaller than 15mm in shell width do not exhibit and Perkinsus sp. while other clams greater than 20mm in shell width exhibit almost 100% infection. To determine the number of Perkinsus sp. in the clams, FTM cultured clam tissues were digested with 2M NaOH solution and the number of hypnospores in the tube were counted. The number of hypnospores counted from the tissues indicated that each Manila clam contains 100,000 to 3,500,000 Perkinsus cells or 20,000 to 1,000,000 cells per gram tissue wet weight. The results of cell counts also suggests that such a high occurrence of Perkinsus sp. in the clam may cause mortality, as already reported from other studies of Perkinsus spp.

• 한국어병학회지
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• 제23권2호
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• pp.145-153
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• 2010

내용은 2009년 하반기, 우리나라 남해안(고흥, 나로도)과 서해안(선재도, 파도리)의 네 지점에서 시료채취 한 바지락에서의 Perkinsus olseni 감염에 대한 모니터링 결과로, 이전에 국제수역사무국(OIE)의 manual에서 지정하던 P. olseni에 대하여 특이적인 primer set으로 사용한 PCR 분석 결과와 2009년에 새로이 지정하는 P. olseni에 대하여 특이적인 primer set을 사용한 분석 결과를 비교하고, 결과를 통한 P. olseni의 검출율을 조사하였다. 특히 2009년에 새로이 지정된 PolsITS-140F와 PolsITS-600R의 primer set을 사용한 결과는 신속한 검출여부 분석에 적합한 것으로 생각되었다. P. olseni의 검출경향은 파도리에서 가장 낮았으며, 고흥에서 가장 높았다. 파도리의 7월, 8월 그리고 12월의 결과를 제외하고는 전 지점에서 7월에서 12월까지 지속적으로 높은 검출율을 나타내었다. PolsITS-140F와 PolsITS-600R의 primer set을 이용한 PCR 산물의 염기서열을 분석한 결과, 선재도의 결과에서 두 군데의 염기차이를 나타내는 것 이외에는 모두 같은 것으로 확인되었다.

• 한국수산과학회지
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• 제33권3호
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• pp.213-218
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• 2000

전북 곰소만에 서식하는 바지락, Ruditapes philippinarum을 대상으로 $18{\circ}C$와 $25{\circ}C$에 순응시킨 후 수온상승 ($1{\circ}C/day, 2{\circ}C/day$ 및 $3{\circ}C/day$) 및 염분 ($32.0, 25.6, 19.2, 12.8, 6.40$ 및 $3.20{\%_{\circ}}$) 변화에 따른 생존율, 여수율 및 산소소비율 둥을 조사하였다. $18{\circ}C$와 $25^{\circ}C$에 순응시킨 바지락의 반수치사온도 (LT-(50))는 두 순응온도구간에 차이를 나타내지 않았으나, 최대 임계온도는 $18^{\circ}C$에 순응시킨 실험구는 $36^{\circ}C$, 그리고 $25^{\circ}C$에 순응시킨 실험구는 $37^{\circ}C$로 고수온에 순응시킨 실험구에서 높았다. 염분변화에 따른 바지락의 생존율은 $19.2{\%_{\circ}}$이하에서 감소하였다. 산소소비율은 $18^{\circ}C$에 순응시킨 바지락의 경우, 염분감소에 따라 감소한 반면 $25^{\circ}C$에 순응시킨 실험구에서는 산소소비율이 불규칙하였다. 한편, 수온증가에 따른 여수율은 $18{\circ}C$에 순응시킨 실험구의 경우 $24^{\circ}C{\~}28^{\circ}C에서$, $25{\circ}C$에 순응시킨 실험구의 경우는 $31{\~}33^{\circ}C$에서 최대를 보인 후 감소하였으며, 염분변화에 따른 여수율은 염분감소에 따라 감소하는 경향을 나타내었다.