• Title/Summary/Keyword: R. philippinarum

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Effect of Cryoprotectants on the Cryopreservation of Manila Clam, Ruditapes philippinarum Embryo (바지락 발생배의 냉동보존에 관한 보존액의 효과)

  • Kang, Kyoung Ho
    • Journal of Convergence for Information Technology
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    • v.11 no.1
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    • pp.128-135
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    • 2021
  • The possibility and effectiveness of cryopreservation was determined to assess survival rates and improve stock management of thawed embryos of Manila clam, Ruditapes philippinarum. The ideal freezing rates were designed and tested to allow cryoprotectants to equilibrate across the membrane during freezing. Survival rates ranging from 0 to 64.3% were obtained using a stepwise freezing protocol compared with 82.3% control rates. Embryos of Ruditapes philippinarum were equilibrated in 2 CPAs plus sea water for 10 min at 25℃ and then cooled at -1℃/min from 20℃ to -12℃. Straws containing more than 100 embryos were held at 12℃ for 5 min allowing equilibration after seeding and slowly cooled at 2℃/min. to -35℃ for 30 min for equilibration before quenching in liquid nitrogen. Dimethyl sulfoxide (DMSO) is the best cryoprotectant indicated for embryos of R. philippinarum with a survival rate of 64.3±3.28% in the presence of 2.0 M DMSO.

Genetic Characterization based on a rDNA Spacer, ITS2 and mtDNA, mtCOI Gene Sequences of Korean Venus Clam, Ruditapes philippinarum

  • Park, Gab-Man;Chung, Ee-Yung;Hur, Sung-Bum
    • Proceedings of the Korean Society of Fisheries Technology Conference
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    • 2000.05a
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    • pp.497-498
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    • 2000
  • The venus clam, Ruditapes philippinarum, is an aquaculture shellfish mainly distributed in an intertidal zone of East Asia including Korea, China and Japan. The morphological variation of this species is great. In fact, two of the most popular markers used in molecular evolution, mitochondrial DNA (mtDNA) and nuclear ribosomal DNA (rDNA), have quite different properties, which could translate into different consequences of mutation, drift, migration and selection on patterns of geographical variation and molecular divergence. (omitted)

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Ecological Study of Shortnecked Clam Ruditapes philippinarum from the Jindu Coast of Hansan Island, Korea (한산도 진두해역 양식 바지락의 자원생태학적 연구)

  • Cho, Sang-Man;Jeong, Woo-Geon
    • The Korean Journal of Malacology
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    • v.23 no.1
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    • pp.25-30
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    • 2007
  • In order to estimate the ecological parameters of the population, short-necked clams, Ruditapes philippinarum, were collected from Jindu coast at Hansan Island, from April to December in 2005. The growth of the clam was estimated by von Bertalanffy growth model and each parameters were obtained from a nonlinear regression as $L_{\infty}\;=\;48.8\;mm$, k = 0.28 and $t_0\;=\;-0.88\;(R^2\;=\;0.994)$. Instantaneous coefficient of total mortality (Z) and fishing mortality (F) was calculated to be 0.8614/yr. and 0.6122/yr, respectively. The age at the first capture was estimated to be 2.88 year. Using the present parameter for clam fishing, the yield-per recruit (Y/R) was estimated to be 3.44g. Although the maximum Y/R was obtained under the parameters ($t_c\;=\;3.48\;yr$. and F = 0.9295/yr), it is favorable to maintain the current fishing effort considering the annual fluctuation of the parameters.

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Cadmium Accumulation and Elimination in the Tissues of the Manila Clam, Ruditapes philippinarum, after Sub-chronic Cadmium Exposure

  • Jang, Seok-Woo;Kim, Seong-Gil;Choi, Ok-In;Kim, Seong-Soo;Kang, Ju-Chan
    • Fisheries and Aquatic Sciences
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    • v.12 no.4
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    • pp.324-330
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    • 2009
  • Cadmium (Cd) accumulation and elimination were assessed in the tissues of the clam R. philippinarum at four experimental concentrations (control, 10, 20, 100, and $200\;{\mu}g/L$) over an exposure period of 2 weeks and an elimination period of 1 week. Cd accumulated in the digestive gland, gill, and residual clam tissues, and accumulation increased with time of exposure and concentration (100 and $200\;{\mu}g/L$). After 2 weeks of Cd exposure, the order of Cd accumulation in tissues was gill > digestive gland > residual tissues. An inverse relationship was observed between concentration factor (CF) and exposure level, but the CF showed an increase with exposure time. During the depuration period, Cd concentrations in the digestive gland, gill, and residual tissues decreased immediately on the cessation of exposure, except in individuals at the $200\;{\mu}g/L$ concentration. The Cd elimination rate from tissues decreased in the order of digestive gland > gill > residual tissues during the depuration period.

Study on natural short-necked clam, Ruditapes philippinarum, stocks in Yeongheung coast of Wando Island, Korea (완도 영흥지선 연안의 천연 바지락 자원에 대한 연구)

  • Cho, Sang-Man;Lee, Jong Hwa
    • The Korean Journal of Malacology
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    • v.28 no.2
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    • pp.109-116
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    • 2012
  • In order to understand the effect of introduction of oyster rack culture on natural short-necked clam, Ruditapes philippinarum, stock, we investigated the status of natural clam stock prior to introduction of oyster rack culture at Yeongheung Coast of Wando Island. The growth equation of the clam was estimated as: $L_t=61.46{\cdot}(1-e^{-0.172(t+0.155)})$ from ring radius composition of shell. Instantaneous coefficient of total mortality and natural mortality were calculated as: 2.4087/year and 0.478/year, respectively. The age at first capture was estimated to be 2.55 year. The total biomass was estimated to 3.23 ton in the bed (0.8 ha). Applied by these parameters, the annual recruit biomass and the current yield per recruit (Y/R) was corresponded to $114.7individuals/m^2$ and $92.0g/m^2$, respectively. Maximum sustainable yield (MSY) was estimated 0.77 ton/year which was close to annual catches, 0.74 ton/year, in the area.

Gonadal Maturation and Artificial Spawning of the Manila Clam, Ruditapes philippinarum (Bivalvia: Veneridae), in Komso Bay, Korea

  • Chung Ee-Yung;Hur Sung Bum;Hur Young-Baek;Lee Jung Sick
    • Fisheries and Aquatic Sciences
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    • v.4 no.4
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    • pp.208-218
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    • 2001
  • We have investigated the gonad index (GI), gonadal development, reproductive cycle, first sexual maturity, sex ratio, the number of spawned eggs and spawning frequency of the Manila clam, Ruditapes philippinarum. Samples were collected from the intertidal zone of Komso Bay, Korea from January to December in 1999. Monthly changes in the gonad index (GI) and condition index showed a similar pattern in the reproductive cycle. The spawning period was once a year between early June and early October, there was a spawning peak between July and August when seawater temperature was over $20^{\circ}C$. The reproductive cycle of this species can be categorized into five successive stages; early active (February to March), late active (April to May), ripe (April to August), partially spawned (June to October), and spent/inactive stage (August to March). Percentages of first sexual maturity of female and male clams of l5.1-20.0mm in shell length were $56.3\%$ and $60.0\%$, respectively, and $100\%$ for the clams >25. mm. The sex ratio of individuals >15.1 mm in shell length was about 1:1 $(\chi^2= 0.02,\;p>0.05)$. Number of the eggs released from each clam by the induction increased as the size of clam in terms of shell length increased. Mean number of the eggs from the second induction of the spawning was $75.35-84.30\%$ $(average\;79.81\%)$ of the number of the eggs released in the first spawning. Our data indicated that R. philippinarum in Komso Bay has one major spawning peak with over two minor spawning, and the interval of each spawning was estimated to be approximately 15-17 (average 16.5) days.

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Molecular Phylogeny of Veneridae (Bivalvia: Heteroconchia) on the Basis of Partial Sequences of Mitochondrial Cytochrome Oxidase 1 (백합 과 패류의 mtCOI 일부 염기서열을 이용한 계통분류)

  • Kim, Jae-Jin;Kim, Sei-Chang;Hong, Hyun-Chul
    • The Korean Journal of Malacology
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    • v.20 no.2
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    • pp.171-181
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    • 2004
  • Partial sequences of the mitochondrial cytochrome oxidase subunit Ⅰ(mtCOI) gene of veneroid clams were obtained to eluciadate molecular phylogeny. A total of nine veneroids and one corbiculid were collected from southern and western sea of Korea. The mtCOI sequences of the clams obtained from the present study and three veneroids sequences from GenBank were analyzed by maximum parsimony and neighbor-joining methods. The subfamilies Samarangiinae, Dorsiniinae, Cyclinae, Meretricinae and Chioninae were monophyletic, but Pitarinae was paraphyletic. One transitions and two transversions among two samples of Ruditapes philippinarum and a R. variegata were observed.

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Antimicrobial Resistance and the Presence of Virulence Genes in Escherichia coli Strains Isolated from Ruditapes philippinarum in Gomso Bay, Korea (곰소만 해역의 바지락(Ruditapes philippinarum)에서 분리한 대장균 (Escherichia coli)의 항균제 내성 및 병원성 유전자의 보유성)

  • Kim, Tae-Ok;Eom, In-Seon;Park, Kwang-Ho;Park, Kwon-Sam
    • Korean Journal of Fisheries and Aquatic Sciences
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    • v.49 no.6
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    • pp.800-806
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    • 2016
  • In total, 151 Escherichia coli isolates from Ruditapes philippinarum in Gomso Bay were analyzed for their susceptibility to 18 different antimicrobial agents and for genes associated with virulence. For virulence genes, each strain of the isolates was positive for the enterotoxigenic E. coli (ETEC)-specific heat-stable toxin (estA), enteroinvasive E. coli (EIEC)-specific invasion-associated locus (iaa) gene and enteropathogenic E. coli (EPEC)-specific attaching and effacing (eae) gene. According to a disk diffusion susceptibility test, resistance to ampicillin was most prevalent (23.2%), followed by resistance to amoxicillin (22.5%), ticarcillin (20.5%), tetracycline (18.5%), nalidixic acid (12.6%), ciprofloxacin (10.6%), streptomycin (9.9%), and chloramphenicol (6.6%). More than 35.8% of the isolates were resistant to at least one antimicrobial agent, and 19.9% were resistant to four or more classes of antimicrobials; these were consequently defined as multidrug resistant. Minimum inhibitory concentration (MIC) ranges for the antimicrobial resistance of the 15 different antimicrobial agents of 54 E. coli strains were confirmed by varying the concentrations from $32-2,048{\mu}g/mL$. Overall, these results not only provide novel insights into the necessity for seawater and R. philippinarum sanitation in Gomso Bay but they also help to reduce the risk of contamination by antimicrobial-resistant bacteria.

Gametogenic Cycle and the Number of Spawning Seasons by Quantitative Reproductive Analysis in Female Ruditapes philippinarum in Western Korea

  • Chung, Ee-Yung;Lee, Chang-Hoon;Choi, Ki-Ho;Choi, Moon-Sul;Lee, Ki-Young
    • The Korean Journal of Malacology
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    • v.26 no.3
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    • pp.245-254
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    • 2010
  • For the studies of germ cell development and maturation in the ovary, the gametogenic cycle and the number of spawning seasons per year in female Ruditapes philippinarum were investigated by quantitative statistical analysis using an Image Analyzer System. Compared with the results by qualitative and quantitative analyses, monthly variations in female gonad indice by qualitative histological analysis showed a pattern similar to that of the female gametogenic cycle calculated by quantitative statistical analysis. The number of spawning seasons occurred once per year, from June to October. In quantitative statistical analysis using an image analyzer system, monthly changes in the portions (%) of the ovary area to total tissue areas in females increased in March and reached a maximum in May, and then showed a rapid decrease from June to October when spawning occurred. And also monthly changes in portions (%) of follicle areas to the ovary area and in portions of oocyte areas to ovarian tissue areas in females began to increase in March and reached a maximum in May, and then. rapidly dropped from June to October when spawnig occurred. From these data, it is apparent that the number of spawning seasons occurred once per year, from June to October. Monthly changes in the number of the oocyte per $mm^2$ and in mean diameter of the oocyte in captured image which were calculated for each female slide showed a maximum in May and reached the minimum from December to February. Therefore, female R. philippinarum showed a unimodal gametogenic cycle during the year.

Ovarian Maturation in Female Ruditapes philippinarum on the West Coast of Korea (한국 서해산 바지락, Ruditapes philippinarum의 난소 성숙)

  • Choi, Ki-Ho;Park, Gab-Man;Chung, Ee-Yung
    • Development and Reproduction
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    • v.9 no.2
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    • pp.123-134
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    • 2005
  • Germ cell development during oogenesis, ovarian maturation and first sexual maturity in female Ruditapes philippinarum were investigated by cytological and histological observations. R. philippinarum is dioecious. During vitellogenesis, the Golgi complex, glycogen particles, and mitochondria were involved in the formation of lipid droplets and lipid granules in the cytoplasm of the early vitellogenic oocyte. In the late vitellogenic oocyte, cortical granules, the endoplasmic reticulum, and mitochondria were involved in the formation of proteid yolk granules in the cytoplasm. At this time, exogenous lipid granular substance and glycogen particles in the germinal epithelium passed into the oocyte through the microvilli of the vitelline envelope. The spawning period was once a year between early June and early October, and the main spawning occurred between July and August when seawater temperature was approximately $20^{\circ}C$. The reproductive cycle of this species can be categorized into five successive stages: early active stage(January to March), late active stage(Februaryto May), ripe stage(April to August), partially spawned stage(May to October), and spent/inactive stage (August to February). Percentages of female clams at first sexual maturity of $15.1{\sim}20.0mm$ in shell length were 52.6%(50% of the rate of group maturity was 17.83mm in length), and 100% for the clams >25.1mm.

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