• Korean Journal of Fisheries and Aquatic Sciences
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• v.37 no.2
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• pp.105-115
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• 2004

Growth pattern of the soft clam (Mya arenaria oonogei) was estimated based on samples collected from the Yeongsan River estuary on the southwest coast of Korea between August 1996 and September 1997. Mean density of the clam during study period was $55\;ind./m^2$ and varied monthly from 281 to $8\;ind./m^2.$ The clams from the study area ranged in age from one year to seven years, with shell lengths between 40.4 mm and 104.1 mm and biomass between 8.4 and 152.3 g in total wet weight. The spawing season was estimated to occur between September and October based upon a reduced fatness index, an indication of spawning, during these months. Burial depths increased with growth of the clams and most were found buried between 10 and 20 cm in the sediments. Significant relationships were found between shell length and shell height (SH), total wet weight, (TWt), meat wet weight (MWt), meat dry weight (DWt), ash free dry weight (AFDW) and burial depth. The von Bertalanffy growth equations of the clams were $L_t(mm)=138.98(1-e^{-0.1325(t+0.8853)})\;and\;W_t\;(gTWt)=325.93\;(1-e^{0.1325(t+0.8853)})^{2.6982}.$ These equations suggest that in their first year the clams should reach 31 mm in length with a biomass of 5.7 g in total wet weight.

• The Korean Journal of Malacology
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• v.32 no.1
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• pp.17-23
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• 2016

Ultrastructural studies of oocyte development and vitellogenesis associated with the follicle cells in female Phacosoma japonicus were investigated by electron microscope observations. Vitelloogenesis in the oocytes occured by way of endogenous autosynthesis and exogenous heterosynthesis: vitellogenesis occurred through a process of endogenous autosynthesis, which involves a combined activity of the Golgi complex, rough endoplasmic reticulum, and mitochondria. However, the process of exogenous heterosynthesis involved endocytotic incorporation of extraovarian precursors into the basal region of the early vitellogenic oocytes. In this study, follicle cells, which attached to the previtellogenic and vitellogenic oocytes, were easily found. In particular, the follicle cells were involved in the development of previtellogenic oocytes by the supply of nutrients, and vitellogenesis in the early and late vitellogenic oocytes by endocytosis of yolk precursors. The functions of follicle cells, which attached to mature oocytes, accumulate reserves of lipid granules and glycogen particles for vitellogesis in the cytoplasm of the follicle cells.

• The Korean Journal of Malacology
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• v.27 no.4
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• pp.395-400
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• 2011

Phylogenetic analyses on the Phylum Mollusks has so far been conducted by many researchers in the world. However, there was no report on taxonomic analysis on Acila divaricata vigila which is belonging to Class Bivalvia, Subclass Protobranchia. In this study, we performed molecular phylogenetic analysis on Acila divaricata vigila using 16S rRNA sequence through maximum likelihood method. As a result, it is clearly divided into the legion of mollusk classification unit (when you zoom in order) and represented to support the current classification in the Phylum Mollusca belong to Class Bivalvia, Subclass Protobranchia, Subclass Pteriomorphia, Subclass Paleoheterodonta, Subclass Heterodonta and Subclass Anomalodesmacea. To our knowledge, this is the first report of molecular phylogenetic analysis on Acila divaricata vigila using 16S rRNA gene and these data suggests that 16S rRNA gene will be useful for analyzing the phylogenetic relationship of Subclass Protobranchia.

• The Korean Journal of Malacology
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• v.21 no.2 s.34
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• pp.147-161
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• 2005

To elucidate the phylogenetic relation of the superfamily Veneroidea, we obtained partial 28S rRNA sequences of 14 heterodonts and three pteriomorphs which were collected from Korea and the sequence data of related taxa from GenBank, and analyzed maximum parsimony with PAUP program 750 of the nucleotide positions were variable, 560 of which were informative under conditions of parsimony. Total tree length was 2,765, and consistency index, homoplasy index (HI), and Retention index was 0.4843, 0.5157, and 0.6291, respectively. Intraspecific variation of 28 rRNA of Corbicula fluminea and Sinonovacula constricta was 3.1% and 1.3%, respectively. Pitarinae-Cyclininae-Meretrinae group had a clade and Samaranginae, Chioninae, and Dorsininae were clustered.

• The Korean Journal of Malacology
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• v.27 no.3
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• pp.205-211
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• 2011

This study presents physiological rates of oxygen consumption, ammonia excretion, feeding rates, O/N ratio and assimilation efficiency of the blood cockle, Scapharca subcrenata, determined from specimens collected in Yeoja bay on the south coast of Korea. Physiological parameters were measured monthly under static, laboratory controlled conditions with ambient conditions, and measurements were performed seasonally in order to estimate scope for growth and its probable sources of variation. Oxygen consumption and ammonia excretion rates have been increased as temperature increased with the highest value of August, 2008. Feeding rate was the highest during April whereas the lowest was during August which is a period of gametogenesis with minimum biomass of phytoplankton around sampling area. Assimilation efficiency was not significantly different seasonally and O/N ratio decreased during July to August. The scope for growth was negative during high temperature months(July to August), reflecting the high temperature and low feeding rate, and had its highest positive values during spring and autumn. Data on the physiological parameters and scope for growth of Scapharca subcrenata obtained in this study will be used to assess the carrying capacity for blood cockle cultivation.

• 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.

• Ocean and Polar Research
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• v.38 no.1
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• pp.21-33
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• 2016

Gametogenesis of the comb pen shell, Atrina pectinata (Linnaeus, 1767) (Bivalvia: Pinnidae) on the southern coast of Ulleungdo Island, Korea was assessed monthly (November 2013 to October 2014) using histology. Gametogenesis commenced in January when the surface water temperature was $12.6^{\circ}C$ and pen shells evidenced an early development phase with small oogonia from January to April, although few females exhibited ripe eggs in their follicular epithelium. In April, the oocyte diameter increased rapidly, and fully mature eggs appeared in May. First spawning males and females were observed in June as the surface water temperature reached $19.3^{\circ}C$ and July ($23.2^{\circ}C$) respectively. The spawning activity continued until the end of September. Histology indicated that the spawning peak of the females in Ulleungdo Island was July to August. During October to January, most of the pen shells were in spent and resting stages. Our data suggested that A. pectinata is a summer spawner, and their annual gametogenesis is closely associated with the seasonal variation in the surface water temperature. The present study is the first provided fundamental information on the life history of A. pectinata in Ulleungdo Island, and this can be put to good use in the management of this pen shell in the study area.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.32 no.2
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• pp.192-197
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• 1999

Proximate composition, sterol and $\alpha$-tocopherol ($\alpha$-Toc) contents of 35 species of marine invertebrates (13 species of Bivalvia, 10 species of Gastropoda, 4 species of Cephalopoda, 4 species of Crustacea, 2 species of Ascidacea and 2 species of Holothuroidea), which caught off the coast of Tongyeong of the Southern sea (Nam-Hae), Korea, were determined. Protein content showed relatively high level in herbivorous (seaweed feeder) and carnivorous species such as Gastropoda ($17.2\pm4.30\%$), Crustacea ($16.8\pm4.06\%$) and Cephalopoda ($15.3\pm3.24\%$), but showed low in plankton feeder and mud swallow such as Bivalvia ($11.8\pm2.49\%$), Ascidacea ($8.20\pm1.00\%$) and Holothuroidea ($3.94\pm1.13\%$). Total lipid (TL) content was low in most marine invertebrates, ranged from $0.24\%$ (blue colored sea cucumbers) to $1.96\%$ (sea squirts). Ascidacea contained the largest amount of TL in all samples, while Holothuroidea contained the smallest amount of TL, and other classes contained about $1\%$ of TL. Carbohydrates was rich in plankton feeder and Herbivorous species (seaweed feeder) such as Ascidacea ($6.60\pm4.53\%$), Bivalvia ($3.15\pm1.82\%$) and Gastropoda ($3.02\pm1.61\%$), while poor in carnivorous species such as Crustacea ($0.52\pm0.57\%$) and Cephalopoda ($1.00\pm0.63\%$). Moisture content was highest in Holothuroidea ($92.0\pm1.94\%$) and the lowest in Gastropoda ($77.0\pm1.95\%$): There were negative correlations between moisture and protein content, or TL, between protein and TL content; y= -0.8716x+184.452 (r=-0.87, p<0.001), $y=128.52e^{-0.0601x}$ (r=-0.55, P<0.001), $y=6.3047e^{-0.0904x}$(r=-0.42, P<0.02), respectively. Sterol content was ranged from 56 mg/100 g edible portion of red colored sea cucumbers to 216 mg/100 g edible portion of cockle and was high in the following order; Cephalopoda (148 $\pm$30.0mg)>Bivalvia (121$\pm$35.0mg)>Gastropoda (118$\pm$20.0mg)>Crustacea (116$\pm$31.0mg)>Ascidacea (78.0$\pm$2.00 mg)>Holothuroidea(62.0$\pm$8.00 mg). Crustacea contained 1$\~$2 mg $\alpha$-Toc/100 g edible portion whereas other classes contained trace or less than 1 mg/100 g of edible portion.

• The Korean Journal of Malacology
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• v.11 no.1
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• pp.70-77
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• 1995

The purpose of this study is to determine the differences of the conchiolin layer, prismatic layer and nacreous layer deposited within the shell of the freshwater family Unionidae. shether they possess species-specific characteristics and differences of the microstructure of these layers, A Scanning electron microscopic obwervations were conducted on seven species. The results indicate that all species possess thin and homogeneous layers within the periostracum. The prismatic layers of these species were composed of ednsely packed prisms. The prismatic layers of the shell in six species were typical shape of prisms. especially Inio douglasiae and Lamprotual gottschei. But, in Unio douglasiae sinuolatus, it was irregular and oblique prism shape.The nacreous layer of weven unionids characterized by possession of three types by lamillae shape: thin and homogeneous on genus Anodonta(0.4 pm size of lamella), Unio(1.3pm) and Lamprotual (1.7pm), homogeneous in shape and irregular in size of lamillae in Lanceolaria(1.0 pm)and irregulat in shape and size in Solenaia(0.2-0.4 pm). The microstructure of the naceous layer may be useful as a taxonomic character at the generic level.

• Journal of fish pathology
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• v.24 no.1
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• pp.19-27
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• 2011

The production of surf clam, Mactra veneriformis, an important fishery resource in Korea, has recently been decreasing. This study was carried out to examine effects of spawning on immune functions of this species. Total hemocyte count (THC), phenoloxidase (PO) activity, phagocytic activity, neutral red retention (NRR) time and antibacterial activity were assessed. Spawned clams showed reduction in THC, PO, phagocytic activity and NRR times compared with unspawned ones. While spawning event did not elicit any change of antibacterial activity in both spawned and unspawned ones. This study indicates that spawning process decreases immune functions in the surf clams which could cause mortality increment and yield reduction.