• Korean Journal of Food Science and Technology
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• v.3 no.1
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• pp.52-56
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• 1971

The cooked surf clam meat was treated with BHA or EDTA, and then dehydrated by means of hot-air dehydration or sun drying. The dehydrated products were packed in glass bottle and stored for three months in the dark place. After three month storage, the pigment loss and water absorbing capacity of dehydrated products were compared with those of directly after dehydration. Both of the sun dried and hot-air dehydrated surf clam products showed a great deal of pigment loss during storage. The BHA treatment prior to dehydration of surf clam meat had good effects on the pigment retention, and the EDTA treatment had a weak effect on it during storage. The rate of rehydration of dehydrated surf clam products had markedly decreased during storage. And it could be seen that there was little difference among the rate of rehydration of the BHA or EDTA treated product and untreated one during storage.

• The Korean Journal of Malacology
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• v.30 no.3
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• pp.259-271
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• 2014

This study was conducted to investigate the impact of sand addition to an intertidal for the development of the Manila clam habitat on benthic community structure. For this, we focused on the spatio-temporal changes in the surface sediment condition and benthic community structure including Manila clam before and after the event. Study site was the lower part of Ojjeom tidal flat in Gonam-myeon, Taean-gun where sand added to on July 2010. We set three stations at each of sand adding area (experimental plot) and non sand-adding area (control plot) and did sampling works ten times from June 2010 to October 2011. Directly after the event, surface sediments changed to very coarse sand, but the state was not maintained over two months because of seasonal sedimentation and finally got back to the original grain sizes in eight months. The number of species and density were temporarily reduced right after the event and polychaetes such as Sternaspis scutata, Ampharete arctica were most negatively affected by the event. However, the number of species and density quickly recovered from the reduction in four to six weeks owing to the recolonization by the existing species and species in the vicinity of the plot. However, despite the recovery of ecological indies, species composition was continuously changed from one to another, thereby community structure stayed unstable condition, especially in some stations with finer sediment in their original condition. After sand addition, density of Manila clam was prominently increased at only one station with coarser sediment in its original condition.

• The Korean Journal of Malacology
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• v.24 no.1
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• pp.11-24
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• 2008

GDNA was isolated from the jedo venus clam (Protothaca jedoensis, Lischke) from Boryeong (jedo venus clam from Boryeong JVCB) and Wonsan (jedo venus clam from Wonsan; JVCW) located in the West Sea and the East Sea of Korean Peninsula, respectively and we performed clustering analyses, DNA polymorphisms and the populations genetic variations. In the present study, the seven decamer primer generated the one hundred and eleven major/minor specific bands in JVCB population and ninety four-specific bands in JVCW population. Seven primers generated the unique shared bands to each population of one hundred and seventy-six, on average of 25,1, in JVCB population from Boryeong and three hundred thirty, on average of 47,1, in JVCW population from Wonsan, respectively. The dendrogram obtained by the seven oligonucleotides primers, indicates two genetic clusters. Especially, two Protothaca between the individual WONSAN no. 12 and BORYEONG no. 10 showed the longest genetic distance (0.537) in comparison with other individuals used. Accordingly, RAPD analysis showed that the JVCB was a little more genetically diverse than the JVCW population. This result implies the genetic similarity owing to rearing in the same and/or similar circumstances or inbreeding within the JVCW population. So to speak, JVCB population may have high levels of genomic DNA variability owing to the introduction of the wild individuals from the other sites to sampling sites although it may be the geographically diverse distribution of this species. However, it was confirmed that it did not appear like that really in this study. We feel convinced that RAPD analysis discovered a significant genetic distance between two Protothaca population pairs (P<0.001). The existence of population discrimination and genetic diversity between two Protothaca populations was identified by RAPD analysis.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.4 no.1
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• pp.17-21
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• 1971

The effect of EDTA or BHA pretreatment upon the color preservation of canned surf clam meat during canning and storage was studied. The steamed surf clam meat was soaked in BHA solution, $0.1\%$ BHA in $5\%$ salt solution, or EDTA solution, $0.5\%\;Na_2$ EDTA in $5\%$ salt solution, for 30 minutes. The pretreated surf clam meat was packed in a round enameled can that is 223.2 ml by volume and sterilized for 75 minutes at $110^{\circ}C$. The canned products were stored for one year at room temperature. The EDTA treatment of surf clam meat appeared effective on color preservation during processing. After three month storage, the samples showed little color change comparing with those right after processing. After one year storage, EDTA or BHA treated samples showed better color preservation as compared with control.

• The Korean Journal of Pharmacology
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• v.8 no.1
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• pp.15-25
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• 1972

Korean aconitum (Aconitum koreanum R. Raymond) as one of the botanical crude drugs which pertain to helleboraceae has been extensively applied in Chinese medicine during the past decades. It has been particularly used in immortal tonic among the folk remedies in China, however, its general uses comprehend diuresis, cardiotonic, analgesia, neuralgia, gout and, furthermore, even neoplastic effect. The components of aconitum have been acknowledged as aconitine, mesaconitine, hypaconitine, aconine and so on. The main ingredient, aconitine has the advantage of causing the atrial fibrillation, but, its pharmacological research has not been fully elucidated. Although there are many reports with regard to the pharmacological effects on the motility of several animal hearts, their conclusions have not been regretfully coincided yet. The authors hereby paid attention to this point of view and made experiment to examine the relationship between the alcohol extract of Korean aconitum and the motility of the isolated clam heart, making the use of several drugs related to the heart such as serotonin, acetylcholine, pilocarpine, physostigmine, barium chloride, procaine and quinidine. The cardiac movement of the isolated clam (Meretrix lusoria) heart in the standard sea water solution was recorded with the electric kymograph according to the Magnus method. The results of the experiment are as follows. 1. The motility of the isolated clam heart represents the tendency of gradual inhibition in proportion to the concentration of AK-A $10^{-4}$, $5{\times}10^{-4}$, and $10^{-3}$. 2. The cardiac inhibitory effect of AK-A $10^{-3}$ antagonizes the motility of the isolated clam heart pretreated with serotonin $10^{-6}$. 3. The cardiac inhibitory effect of AK-A $10^{-3}$ antagonizes the systolic state appealed by barium chloride $10^{-3}$. 4. The systolic state caused by quinidine $10^{-4}$ is not inhibited by AK-A $10^{-3}$.

• Korean Journal of Veterinary Service
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• v.40 no.4
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• pp.265-275
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• 2017

The production of enzymes that help digestion, assimilation of essential nutrients, and prevent pathogenic bacteria are important for probiotics used in aquaculture. The objective of this study was to investigate enzyme activities for macromolecular organic matters and antimicrobial properties of the selected potential probiotics isolated from gut of surf clam (Tresus keenae) against well-known shellfish-pathogenic bacteria. Among 65 isolates from guts of 60 surf clams, seven Bacillus strains with outstanding degradation capability of macromolecule organic matter were selected as potential probiotics as follows: TKI01 (B. vietnamensis), TKI02, TKI26 (B. thuringiensis), TKI14, TKI32, TKI42 (B. amyloliquefaciens), and TKI18 (B. stratosphericus). After in vitro antimicrobial activity test was performed against five shellfish-pathogenic bacteria including Listonella anguillarum, Vibrio parahaemolyticus, V. splendidus, V. harveyi, V. tubiashii, PCR assay was performed to detect bacteriocin-producing strain. PCR results revealed that the five Bacillus strains possessed diverse bacteriocin genes including ericinA, coagulin, surfactin, iturin, bacyllomicin, fengycin, bacylisin, subtilin, and lantibiotics. In the present study, the selected seven Bacillus strains showed different enzyme activities according to types of macromolecule organic matters. And their antimicrobial activities varied based on the species of pathogenic bacteria. In addition, at least five Bacillus strains had genetic potential to produce several natural lipopeptide antibiotics that may help biological control of surf clam aquaculture. Therefore, mixed use of probiotics might show co-operative effect and increase the efficiency of probiotics rather than separate use. To the best of our knowledge, it is the first report on antimicrobial properties of Bacillus species isolated from surf clam.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.36 no.3
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• pp.210-219
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• 2003

To develop natural flavoring substances, optimal two stage enzyme hydrolysis conditions and flavor compounds of short-neck clam (Tapes philippinarum) enzyme hydrolysates were examined. The optimal enzyme hydrolysis conditions for two stage enzyme hydrolysate (TSEH) of short-neck clam were revealed in temperature at $55^{\circ}C$ for 4 hours digestion with alcalase at the 1st stage and 4 hours digestion at $45^{\circ}C$ with exopeptidase type neutrase at the 2nd stage. In quality tests of hot-water extracts, steam extracts and 4 kinds of enzyme hydrolysates, TSEH processing method was superior to other methods in yield, nitrogen contents, organoleptic taste such as umami intensity and inhibition of off-flavor formation, and transparency of extract. Total free amino acid contents in hot-water extract, steam extract and TSEH were 1,352.1 mg/100 g, 1,174.1 mg/100 g and 2,122.4 mg/100 g, respectively, Major free amino acids in TSEH were glutamic acid, glycine, alanine, tyrosine, phenylalanine and arginine. As for nucleotides and other bases, betaine, TMAO and creatinine were principal components in TSEH. The major inorganic ions in TSEH were Na, K, P and Cl. TSEH also revealed very higher angiotensin-I converting enzyme inhibition effect $(70.7\%)$ than those of hot-water and steam extract. We conclude that TSEH from short-neck clam was more flavorable compared with the seasoning materials on the market, it could be utilized as the instant soup base and the seasoning substances for fisheries processing.

• Proceedings of the Korean Environmental Health Society Conference
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• 2004.12a
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• pp.63-68
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• 2004

Immunohistochemical and ultrastructural experiments were conducted to find out heavy metal accumulation in some selected organs such as the kidney, the digestive gland, and the gill of the Antarctic clam Laternula elliptica and R. philippinarum. According to the immunohistochemical study the subject organs of the clam showed reactions indicating the presence of MT (metallothionein), a metal-binding protein involved in metal detoxifying process. Examination under the transmission electron microscope also revealed that other ligands may play a role in metal accumulating and detoxifying process in L. elliptica and R. philippinarum. In the artificial exposure of the clam to Cd, the clams showed immediate subcellular responses. The level of the anti-MT reactions became higher in the proportion to the degree of pollution of their habitat and to the period of Cd exposure. These suggest that the two species can be used as efficient biomarkers for Cd exposure in the natural environment.

• Journal of Aquaculture
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• v.10 no.3
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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.

• Ocean Science Journal
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• v.40 no.2
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• pp.79-89
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• 2005

Laboratory radiotracer experiments were conducted to determine assimilation efficiencies (AE) from ingested algal food and oxic sediment particles, uptake rates from the dissolved phase, and the efflux rates of Cd, Cr and Zn in the Asiatic clam Corbicula fluminea. Among three elements, AE from both algal and sediment food was greatest for Cd, followed by Zn and Cr. The AEs of tested elements from algal food (Phaeodactylum tricornutum) were consistently higher than those from sediments at a given salinity and temperature. The influence of salinity (0, 4 and 8 psu) and temperature (5, 13 and $21^{\circ}C$) on the metal AEs was not evident for most tested elements, except Cd AEs from sediment. The rate constant of metal uptake from the dissolved phase $(k_u)$ was greatest for Cd, followed by Zn and Cr in freshwater media. However, in saline water, the $(k_u)$ of Zn were greater than those of Cd. The influx rate of all tested metals increased with temperature. The efflux rate constant was greatest for Cr $(0.02\;d^{-1})$, followed by Zn $(0.010{\sim}0.017\;d^{-1})$ and $Cd\;(0.006\;d^{-1})$. The efflux rate constant for Zn in clam tissues depurated in 0 psu $(0.017\;d^{-1})$ was faster than that in 8 psu $(0.010\;d^{-1})$. Overall results showed that the variation of salinity and temperature in estuarine systems can considerably influence the metal bioaccumulation potential in the estuarine clam C. fluminea. The relatively high Cd accumulation capacity of C. fluminea characterized by the high AE, high dissolved influx rate and low efflux rate, suggested that this clam species can be used as an efficient biomonitor for the Cd contamination in freshwater and estuarine environments.