• Development and Reproduction
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• v.3 no.1
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• pp.107-111
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• 1999

To find out the desirable cryoprotectant for cryopreservation of bivalve trochophores, four types of cryoprotectant were tested with trochophores of the pearl oyster (pinctada fucata martensii) generally used in the pearl production in Korea. Each cryoprotectant (dimethyl sulfoxide, ethylene glycol, glycerol and 1,2-propanediol) was mixed with 0.2 M sucrose to make final concentrations of 0.01, 0.1, 1.0 and 2.0 M. The trochophores were immersed in each preparation, waiting for 10 minutes to reach equilibration and cryopreserved in the liquid nitrogen (-l96$^{\circ}C$). Survival rate of trochophores thawed after cryopreservation increased as the media concentration increase. However, a few number of the trochophores seemed to be damaged with the efflux of cell inclusions. Our study rsults indicate that desirable cryoprotectants for cryopreservation of pearl oyster trochophores are 1.0~2.0 M dimethyl sulfoxide and ethylene glycol : 82.8~97.4% of the trochophores cryopreserved with these media survived after thawing.

• Development and Reproduction
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• v.11 no.2
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• pp.79-84
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• 2007

The freezing susceptibilities of two larval stages (D-shaped and umbo) of the pearl oyster (Pinctada fucata martensii) were evaluated by the electron microscopy (light, transmission electron and scanning electron). The morphological shapes were examined from each pre-frozen or frozen-thawed stage of the cryopreserved larvae in liquid nitrogen by using the cryoprotectant, dimethyl sulfoxide ($Me_2SO$) mixed with sucrose. Although a portion of the shell was damaged, the hinge and prodissoconch were intact and clearly visible after preservation in liquid nitrogen. In addition, the cytoplasm of the frozen-thawed larvae maintained the normal organelle integrities, e.g., endoplasmic reticula, lipid droplets, mitochondria, nucleus and microvilli. However, some of the frozen-thawed larvae showed irregularly arranged cilia, rough shell surfaces and round-lumped cilium heads. These results indicate that P. fucata martensii larvae are susceptible to freezing, at least at those two critical developmental stages (D-shaped and umbo), and suggest a new industrial investigation including reduction method of cell injury for preserving microbial starter cultures need to be developed.

• Proceedings of the Korean Society of Embryo Transfer Conference
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• 2002.11a
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• pp.103-103
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• 2002

This study was conducted to investigate cryopreservation of pearl oyster, Pinctada fucata martensii larvae. Four cooling rates (-0.25, -0.5, -0.75 and -1.0$^{\circ}C$/min.) were used to examine a proper cooling rate during cryopreservation of trochophores before seeding temperature (-12$^{\circ}C$). Seven developmental stages (early and late trochophores, early and late D-shaped larvae and early, middle and late umbo stage larvae) and different sugars (fructose, glucose and sucrose) were used to investigate optimal larval stage and effective sugar in cryopreservation of larvae. The survival rates of frozen-thawed trochophores increased at cooling rate of -1.0$^{\circ}C$/min. As larval developing, survival rate of frozen-thawed larvae increased, except umbo stage larvae, and especially late D-shaped larvae highly survived as 91%. Addition of sugar revealed positive effect on cryopreservation in this experiment and 0.2 M glucose and sucrose mixed with 2.0 M dimethyl sulfoxide significantly enhanced survival rate of larvae (P<0.05). The results of our study indicate that desirable cooling rate, developmental stages of larvae and effective sugar far cryopreservation of pearl oyster, P. fucata martensii larvae are -1$^{\circ}C$/min, late D-shaped larvae and 0.2 M glucose and sucrose, respectively.

• Proceedings of the Korean Society of Fisheries Technology Conference
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• 2001.10a
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• pp.285-286
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• 2001

진주조개(Pinctada fucata martensii)는 일본의 남부지역에만 분포하는 종으로 양질의 진주를 생산하는 주된 양식 대상종이다. 우리나라에서는 1960년대 일본으로부터 이식하여 양식하고 있으나, 자연채묘에 의한 종묘 수급에 어려움을 겪고 있다. 이러한 어려움을 해결하기 위해서는 인공 종묘생산이 이루어져야 하며, 이의 확립을 위해서는 건강하고 우량형질을 지닌 어미와 함께 원활한 유생의 공급이 필요하다. 그 한가지 방법으로서 발생배의 대량 냉동보존을 들 수 있는데, 만일 진주조개 배우자의 냉동보존 기술이 확립된다면, 연중 인공 종묘생산과 선발육종이 가능해지고 우량종의 유전자를 보존할 수 있게 된다. (중략)

• The Korean Journal of Malacology
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• v.27 no.3
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• pp.273-282
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• 2011

The ultrastructural characteristics of germ cells during spermatogenesis and mature sperm morphology in male Pinctada martensii were investigated by transmission electron microscope observation. The morphologies of the sperm nucleus and the acrosome of this species are the oval shape and cone shape, respectively. Spermatozoa are approximately $47-50{\mu}m$ in length including a sperm nucleus (about $1.24{\mu}m$ in length), an acrosome (about $0.60{\mu}m$ in length), and tail flagellum (about $45-47{\mu}m$). The axoneme of the sperm tail shows a 9+2 structure. In P. martensii in Pteriidae, a special substructure showing a thick and wide triangular shape which is composed of electron-dense opaque material (occupied about 50% of all, the upper part of the acrosomal vesicle), appeared in the upper region (part) of the acrosomal vesicle, while the lower region (part) of the acrosomal vesicle is composed of electron-lucent material. Thus, this special structure, which exist in the upper part of the acrosomal vesicle in P. martensii, is somewhat different from those of other subacrosomal vesicle in other families in subacrosomal vesicles. Therefore, we assume that the existence of a special substructure showing a thick and wide triangular shape in the acrosomal vesicle of the spermatozoon can be used as a key characteristic for identification of P. martensii or other species in Pteriidae in subclass Pteriomorphia. The number of mitochondria in the midpiece of the sperm of this species are five (exceptionally sometimes four), as one of common characteristics appear the same number of mitochondria in the same families of superfamilyies. This species in Pteriidae does not contain the axial rod and satellite fibres which appear in the species in Ostreidae in subclass Pteriomorphia. These characteristics can be used for the taxonomic analysis of the family or superfamily levels as a systematic key or tools.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.32 no.4
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• pp.476-480
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• 1999

Experiments were carried out to evaluate the tolerance of trochophores for pearl oyster, Pinctada fucata martensii and Pacific oyster, Crassostrea gigas using different concentrations of cryoprotectants : dimethyl sulfoxide (DMSO), ethylene glycol, glycerol and 1,2-propanediol. Each cryoprotectant with different concentrations was exposed for 5, 10, 15 and 20 minutes of immersion time. Survival rates were increased with decreased concentrations of cryoprotectant and decreased immersion time, and these differed from types of cryoprotectant. Survival rates of Pacific oyster trochophores were higher in DMSO and ethylene glycol, while those of pearl oyster trochophores were higher in glycerol and 1,2-propanediol. In case of trochophores from Pacific oyster, when 0.2 M sucrose was added in each cryoprotectant the survival rates were increased significantly.

• Proceedings of the Korean Society of Developmental Biology Conference
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• 2002.02a
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• pp.22-23
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• 2002

• Korean Journal of Fisheries and Aquatic Sciences
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• v.43 no.1
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• pp.54-62
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• 2010

With the aim of developing and indoor overwintering technique for Pearl oyster, Pinctada fucata martensii, the metabolic rates of young oysters (52.4-83.0 mm in shell length) were measured for 2 weeks at water temperatures of 8, 10, 12, and $14^{\circ}C$. The filtration rate (FR) ranged 0 to $4.84\;L\;h^{-1}gDW^{-1}$ (mean, $0.02{\pm}0.06 $ to $3.12{\pm}1.45$), with significant changes observed over thme except for the case of a water temperature of $14^{\circ}C$. Respiration rate (R) ranged from 0 to $2.370\;mgO2\;h^{-1}gDW^{-1}$ (mean, 0 to $1.77{\pm}0.37$), with significant respiratory disorders observed at temperatures below $12^{\circ}C$; in contrast, the rate increased on the $14^th$ day of the experiment in the case of a temperature of 14$^{\circ}C$. No significant difference was observed among the different water temperatures in terms of excretion rate (E) or absorption efficiency (Abs.eff), except for a significant decrease in aerobic metabolism in the case of water temperature of $8^{\circ}C$. The estimated scope for growth (SFG) ranged from -9.1 to $126.9\;J\;h^{-1}gDW^{-1}$ (mean. $-4.1{\pm}2.6$ to $82.85{\pm}42.6$). A significant energy Joss was found at $8^{\circ}C$, with negative SFG observed throughout the experiment and a gradual energy decrease observed over time at water temperatures of $10^{\circ}C$ and 120C. However. SFG remained positive throughout the experiment in the case of $14^{\circ}C$. The estimated minimum energy requirement, assessed from energy expenditure, is $8.00-34.24\;J\;h^{-1}gDW^{-1}$ (mean, $17.67{\pm}6.17$). In conclusion, the lowest temperature suitable for indoor overwintering is above $14^{\circ}C$.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.33 no.6
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• pp.559-564
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• 2000

We studied to find out the effect of water temperature on the egg development of pearl oyster, Pincata fucata martensii and Pacific oyster, Crassostrea gigas. The optimum water temperatures for egg development were $20{\~}25^{\circ}C$ in P. fucata martensii and $15{\~}25^{\circ}C$ in C. gigas. The required time from fertilization to D-shaped lana was $41.7\;hours\;at\;20^{\circ}C$ and 27.5 hours at $25^{\circ}C$ in P. fucata martensii, and 35.3 hours at $15^{\circ}C$, 26.3 hours at $20^{\circ}C$ and 17.6 hours at$ 25^{\circ}C$ in C. gigas, respectively. The relationships between the water temperature ($WT:^{\circ}C$) and the required time (h: hour) from fertilization to each developmental stage were given as follows; P. fucata martensii Up to 8-cell $$1/h=0.0463WT-0.6945 (r^2=0.9702)$$ Up to morula $$1/h=0.0196WT-0.2184 (r^2=0.8118)$$ Up to trochophore $$1/h=0.0076WT-0.0802 (r^2=0.8756)$$ Up to D-shaped larva $$1/h=0.0031WT-0.0380 (r^2=0.9075)$$ C. gigas Up to 8-cell $$1/h=0.0210WT-0.1123 (r^2=0.9862)$$ Up to morula $$1/h=0.0143WT-0.1077 (r^2=0.9833)$$ Up to trochophore $$1/h=0.0052WT-0.0218 (r^2=0.9857)$$ Up to D-shaped lawn $$1/h=0.0029WT-0.0170 (r^2=0.9689)$$ Biological minimum temperature for egg development of P. fucata martensii and C. gigas was calculated as $$12.3^{\circ}C and 5.7{\circ}C$$, respectively.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.39 no.1
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• pp.9-15
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• 2006

As a part of the investigation for utilizing pearl oyster by-products, a rapid salt-fermented pearl oyster using commercial enzyme was prepared and also examined on the characteristics. The salt-fermented pearl oyster prepared by optimal condition, which was prepared by mixing of minced pearl oyster, 15% salt, and 1% $Protamex^\circledR$ and fermented for 4 weeks, was superior in hydrolysis degree (28.7%) and ACE inhibitory activity (92.6%) to salt-fermented pearl oyster prepared by other conditions, such as the use of whole tissue, different enzymes $(Alcalase^\circledR,\;Neutrase^\circledR\;and\;Flavourzyme^\circledR)$, different salt concentrations (20 and 25%), and different fermentation periods (2, 6 and 8 weeks). There were, however, some shortcomings with this product. It showed a dark green color and an unfavorable bitter taste. These shortcomings were improved by the addition of seasoning paste. The calcium and phosphorus contents of the seasoned salt-fermented pearl oyster were 64.2 mg/100 g and 71.6 mg/100 g, respectively, and the calcium content based on phosphorus was a good ratio for absorbing calcium. The total amino acid content of the seasoned and salt-fermented pearl oyster was 7,054 mg/100 g and the major amino acids ware aspartic acid (555.1 mg/100 g), glutamic acid (1,131.2 mg/100 g), alanine (658.2 mg/100 g), and lysine (695.5 mg/100 g). The seasoned salt-fermented pearl oyster, along with angiotensin I converting enzyme (ACE) inhibitory activity (98.3%), also showed a recognizable level (87.5%) of anti-oxidative activity.