• YAKHAK HOEJI
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• v.39 no.3
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• pp.243-251
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• 1995

Three new lectins, MLA-I, MLA-II and MLA-III, have been isolatedand purified from the hemolymph of Meretrix lusoria and reported previously. Biophysicochemical characteristics were investigated with these three MLA lectins. The MLA lectins agglutinated human erythrocytes non specifically and proved as D-galactose group carbohydrate specific. Molecular weight of ML.A-I. II and III were estimated to be 330, 500 and 310KD, respectively, by gel filtration on Sepharose CL-6B column. On SDS-polyacrylamide gel electrophoresis, ML.A-I was dissociated into a single subunit of 42KD, MLA-II was into the twelve subunits of 46, 32, 30, 28, 25, 23. 22, 20. 19, 16, 15, and 14KD, and MLA-III was into the two subunits of 72 and 44KD. The pl of MLA-I, II, III were 4.0. 4.9 and 5.0. Amino acid analysis revealed a high contents of acidic and hydroxy amino acids, and a paucity of sulfur containing amino acids. Proline was not contained in MLA-II.

• Korean Journal of Microbiology
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• v.8 no.4
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• pp.141-150
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• 1970

As a part of taxonomical and ecological studies on the yeasts in marine environments, several kinds of yeasts were isolated from Zostera marina several invertebrates (penaeus, Meretrix and Neptunus) and surface sea water, which are collected at the two established sites of estuarine areas ; Dolsan isaland in Youchun district and Baiksu-ri in Youngkwang district. The obtained results can be summarized as follows. 1. Ascosporgenous Yeasts. Hansenula sp I and Hansenula sp II were isolated from Zotera marina and Hanse nular sp I from penaeus. 2. Asporogenous Yeasts. Trichoporon fermentans, Torulopsis, ernobii and Toruopsis dattia were isolated from Zostera marina, Candida krusei from Meretrix and Neptunus, Torulopsis pinus from surface sea waters, and Phodotorula aurantiaca from Penaeus. 3. More notable isolations of several species from Zostera marina than the other sources could be assumed as related to the higher sugar concentration of this plant.

• Proceedings of the Korean Aquaculture Society Conference
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• 2006.05a
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• pp.654-655
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• 2006

• Proceedings of the Korean Society of Fisheries Technology Conference
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• 1997.06a
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• pp.169.1-170
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• 1997

• Development and Reproduction
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• v.16 no.3
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• pp.205-217
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• 2012

The ovarian cycle, the biological minimum size, and artificial spawning frequency by artificial spawning induction of the female hard clam, Meretrix petechialis, were investigated by histological observations and morphometric data. The ovarian cycle of this species can be classified into five successive stages: early active stage, late active stage, ripe stage, partially spawned stage, and spent/inactive stage. The spawning period was from June to September, and the main spawning occurred between July and August when the seawater temperature exceeds over $20^{\circ}C$. The biological minimum size (shell length at 50% of first sexual maturity) in females were 40.39 mm in shell length (considered to be two years of age), and all clams over 50.1 mm in shell length sexually matured. In this study, the mean number of the spawned eggs by spawning induction increased with the increase of size (shell length) classes. In case of artificial spawning induction for the clams > 40.39 mm, the number of spawned eggs from the clams of a sized class was gradually decreased with the increase of the number of the spawning frequencies (the first, second, and third spawning). In the experiments of artificial spawning induction during the spawning season, the interval of each spawning of this species was estimated to be 15-18 days (approximately 17 days).

• Korean Journal of Fisheries and Aquatic Sciences
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• v.13 no.4
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• pp.173-178
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• 1980

Cercaria larvae of Bacciger harengulae which is parasitic to Meretrix lusoria, rapes japonica and Solen strictus were studied in terms of their morphology and incidence of infection rate. The host bivalves were collected from Naechodo, Okgu-gun during the Period from January to November in 1980. The tail of the cercaria bears 27 pairs of tufts of setae, the tufts being composed of 6 fine rays. Oral sucker, intestine, ventral sucker and a pair of testes are distinctive. The excretory duct bears numerous granules of various size, and the flame-cell arrangement is represented by a formula 2[(3+3)+(3+3)]=24. The cercaria is somewhat similar to the previously known Cercaria pectinata . It is however conformed that present cercaria belongs to Bacciger harengulae. Infection rate showed seasonal variation and host selectivity. Higher infections were observed in Solen strictus, and lower in Meretrix lusoria. Generally, the larger bivalves over 2-3 years old showed the higher infection rate.

• The Korean Journal of Malacology
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• v.24 no.1
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• pp.67-72
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• 2008

This study investigated the proximate composition in the muscle and viscera of five commercially valuable Korean Veneridae, Protothaca jedoensis, Ruditapes philippinarum, Saxidomus purprratus, Cyclina sinensis and Meretrix lusoria. The proximate analysis revealed that the moisture, crude protein and carbohydrate of muscle in higher than viscera. As results, except for the crude lipid and carbohydrate there was little significant differences among the moisture, protein and crude ash. The crude lipid contents was highest in the viscera of Meretrix lusoria, while lowest in the muscle of Ruditapes philippinarum. The carbohydrate content of viscera in the Meretrix lusoria, Ruditapes philippinarum and Protothaca jedoensis were $3.61{\pm}0.45%$, $3.45{\pm}1.4%$ and $3.39{\pm}0.07%$, respectively.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.9 no.1
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• pp.35-42
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• 1976

Larval morphogenesis and infection rates of Cercaria pectinata Huet were investigated in regards to histological changes and mortality of the hard clam, Meretrix lusoria $(R\ddot{o}ding)$, in Buan located on the Western Coast of Korea. The trichocerous cercariae, Cercaria pectinata, and its sporocysts parasitize mainly in the tissues of goand, digestive gland and gills of the hard clams. One branched sporocyst grows into a great number of cylindrical sporocysts, and a heavily infected clam possesses 2,000 to 5,000 cylindrical spo ro cysts. Each of them produces approximately 30 to 70 germinal cells and cercariae. Of 2,639 clams examined 347 individuals $(13.2\%)$ were found to be infected. The infection rates showed seasonal variations, the rate being highest $(29.6\%)$ in July, and lowest $(2.0\%)$ in March. Whereas, the infection rates did not change significantly with the changes of size class of the shell. No infection was observed in Meretrix petachialis (Lamarck) collected from Myeong-ji, Kimhae Gun located near Busan. In the iefected clams, the gametogenesis (oogenesis and apermatogenesis) did not undergo completely, therefore the heavily infected clam seemed to be castrated. Also the tissues of the digestive gland and gills were compressed by the multiplication of the parasites. When they were kept in aquariums in the laboratory, high mortality has occurred in the infected clams. All of the 60 infected clams died within 35 days.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.9 no.1
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• pp.69-73
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• 1976

Mortality of clam, Meretrix lusoria was measured during the experimental cultures in different sediments compositions and in different salinities of sea water. Experimental groups maintained in silt and clay showed significant mortality, while those treated in sand and in sand-silt showed little mortality. In the groups cultured in silt and clay, young groups of approximately 2.5cm in shell length were subjected to early and high mortality (approximately eighty-five per cent in foully-one days). The larger the shell size was, the later and the lower the mortality occurred. In different salinity, the groups maintained in silt and clay showed different mortalities. It is observed that the survival rate of the shell in the sea water of low salinity was higher than that in the high salinity water. Oxygen consumption of isolated gill tissue showed a little difference between the groups maintained in silt and clay and those in sand (the control-group). Consequently, it may be stated that the mortality results mainly from the deposition of silt and clay, although the survival rate of Meretrix lusoria depends also on water temperature, salinity, dissolved oxygen, body size ana other factors.

• Journal of Aquaculture
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• v.17 no.3
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• pp.197-208
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• 2004

Five commercially valuable Korean Veneroid, Protothaca jedoensis, Ruditapes philippinarum, Saxidomus purpuratus, Cyclina sinensis and Meretrix lusoria were recognized by comparing internal and external morphological characters. As length of the primary tooth was directly grown proportional to shell size but all other characters were not measured according to size of shell. Hence, the morphological characters of these Veneroids may be estimated from the size of the unique primary tooth and it might be enough to be a good criterion for identification of species among Veneriods. Numerical index of hinge plate length of these species was assessed systematically, irrespective of measuring the length, height and width of the shell. The highest internal and external morphological similarity was observed between P. jedoensis and R. philippinarum and the lowest similarity was observed between P. jedoensis and M. lusoria. These similarities may be affected by multiple environmental factors as well as genetic characters. For artificial seed production of P. jedoensis, R. philppinarum, a closest relative among the five species, must be focussed.