• Journal of Aquaculture
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• v.15 no.1
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• pp.7-13
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• 2002

Since 1993, the White Spot Syndrome Virus (WSSV) disease occurred in China among cultured shrimps resulting in mass mortality. Epizootiological surveys undertaken during the outbreak period of 1993-1994 indicated that all stages of Penaeus chinensis, P. japonicus and P. monodon were infected. Consequent to the transport of contaminated shrimp seedlings and seawater, the disease spread all over the farms of China. The disease was more rapidly transmitted at temperatures above $25^{\circ}C$. Challenge experiments showed the causative agent was highly virulent. White spots appeared on the carapace of both span-taneous and experimentally infected shrimps. Moribund shrimps contained turbid hemolymph, hypertrophied Iymphoid organ and a necrotic mid-gut gland. Electron microscopy showed the presence of viral particles in the gills, stomach, lymphoid organ, and epidermal tissue of the infected shrimp. The visions were slightly ovoid with an envelope and averaged 350 $\times$ 150 nm; nucleocapsids measured 375 $\times$ 157 nm. With discontinuous sucrose gradient of 35, 50 and 60% (w/v), the virus was separated from hemolymph of the infected shrimp. The estimated molecular weight of genomic DNA was 237 Kb with EcoR I, 247 Kb with Hind III and 241kb with Pst I. A total of 9 hybridoma colones secreting monoclonal antibodies (MAbs) were produced from mouse myeloma and spleen cells immunized with WSSV. The immunofluorescence assay of gill tissue showed that the MAbs reacted with diseased but not with healthy shrimp. The MAbs belonged to IgGl, IgG2b subclass and IgM class, all with kappa light Immune-electron-microscopy with colloidal gold marker showed the presence of 5 MAbs epitopes on the envelope and one on the capsid of the virus. Baculoviral mid-gut gland necrosis showed the specificity of the MAbs produced. For diagnosis 5 different methods were selected. Using Kimura primers for PCR, or MAbs for immunoblot, ELISA or FAT method, in situ hybridization was carried out to show the gene. All these methods detected WSSV in the organ samples of the diseased shrimp but not in healthy one.

• Fisheries and Aquatic Sciences
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• v.9 no.4
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• pp.153-159
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• 2006

The ark shell (or 'blood clam') Scapharca broughtonii is a filter-feeding bivalve that has red blood and inhabits waters approximately 10m in depth off the southern coast of South Korea. This study was part of a larger research project investigating the causes of death and restoration of shellfish resources, which are important aquaculture products in South Korea. We examined physiological responses related to survival, respiration, excretion, and amino acid changes as a result of changes in salinity. The 9-day median lethal salinity ($LS_{50}$) was 16.5 psu with confidence limits of 14.9-18.1 psu. At $25^{\circ}C$, the oxygen consumption and ammonia-nitrogen excretion rates were increased with decreases in salinity. Although the osmolality of individuals was acclimated within 2 h at 26.4 psu and 12 h at 19.8 psu, it took more than 5 days at a salinity of 13.2 psu, whereas no individuals acclimated and all died at a salinity of 6.6 psu. Of the amino acids present in the blood, taurine and alanine increased in response to decreased salinity. Tissues of the gill and the mid-gut gland were affected by decreasing salinity. These data will provide important fundamental information for examining the causes of mass mortality of shellfish in the summer.

• International Journal of Industrial Entomology and Biomaterials
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• v.33 no.2
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• pp.113-120
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• 2016

Bombyx mandarina is widely accepted as ancestor of B. mori. Silkworms are served as well-characterized models for understanding the mechanism for the genetic regulation of development. In this study, we performed RNA-Seq analysis to examine tissue-expression of gloverin isoforms of the silk-gland, mid-gut, and fat body in B. mandarina. BLAST analysis revealed that four gloverin isoform gene sequences of B. mandarina were highly similar to B. mori. To identify the difference between two species, the expression profile of gloverin was measured by semi- RT-PCR analysis. The specific expression of gloverin isoform genes was observed mainly in the fat body from B. mori but not B. mandarina. However, all of tissues in the wild-type silkworm could induce the upregulation of compared with the B. mori. To validate the sudden increase in gloverin gene expression in the mid-gut tissue of B. mandarina, we were using qRT-PCR. Relative mRNA expression rate of gloverin at the wild-type silkworm was much higher than domestic silkworm. Comparative genomics between domesticated and wild silkworms showed different tissue-expression levels in some of immune related genes. These results are suggesting a trend toward decreasing immunity related genes expression during domestication. Further studies are needed to elucidate the silkworm domestication and an invaluable resource for wild silkworm genomics research.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.40 no.2
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• pp.63-67
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• 2007

To prevent food poisoning after ingesting sea snails containing tetramine we measured the tetramine $[(CH_3){_4}N^+]$ contents of sea snails from the Korean coast using both ion chromatography (IC) and spectrometry. In total, 177 sea snails were collected from the east (Pohang, 19 species, 95 individuals), the west (Gunsan, 4 species, 46 individuals), and the south (Tongyeong, 8 species, 36 individuals) coasts. The working solution of tetramine standard for IC and the tetramine extract from the salivary gland of Neptunea arthritica cumingii were very stable for one month at $18^{\circ}C,\;4^{\circ}C$, and room temperature. The tetramine content was high in the salivary gland of Heptunea species such as N. intersculpta $(9,813{\mu}g/g)$, N. arthritica $(8,240{\mu}g/g)$, N. arthritica cumingii $(6,967{\mu}g/g)$, N. eulimata $(6,946{\mu}g/g)$, N. constricta $(5,965{\mu}g/g)$, and N, amianta $(4,502{\mu}g/g)$. The mid-gut gland and muscle contained small amounts of tetramine. The tetramine content was highest in the autumn, but no clear regional variations were observed.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.40 no.1
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• pp.16-23
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• 2007

Nonylphenol (NP) is an estrogen-mimicking compound or xenoestrogen. This study investigated the effects of nonylphenol on the reproductive status of the equilateral venus Gomphina veneriformis. The experiment lasted 24 weeks, Experimental groups consisted of a control and three nonylphenol exposures ($1.0,\;2.5,\;and\;5.0\;{\mu}g\;NP/L$). Mortality did not differ significantly between the control and the exposure groups. The sex ratio (F:M) was 1:1 in nature and 1:1.03 in the control group. However, it changed to 1:3.5 with $5.0\;{\mu}g\;NP/L$ exposure. Gonad maturity in females was higher in the nonylphenol exposure groups than in the control group. By contrast, in males, it was lower in the nonylphenol exposure groups. Intersex individuals constituted 0% in nature, 3.08% in the control group, and 23.6% in the group exposed to nonylphenol, with female characteristics more prevalent than male. As the concentration of nonylphenol increased, the accumulation of lipofuscin increased in the mid-gut gland.

• Journal of Aquaculture
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• v.17 no.3
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• pp.215-220
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• 2004

Using light microscopy, the digestive tract of the parrot fish, Oplegnathus fasciatus was studied histologically. The tract consists of esophagus, stomach, intestine and fifty or sixty pyloric caecae. Each pyloric caecum is a blind sac of banana shape, and is originated from pyloric end of the stomach. The relative length of gut (RLG), that is length of digestive tract to standard length, is 1.78 (n=30). Esophagus has an undeveloped submucosa and a well developed muscularis mucosae. Its mucosa displays primary and secondary folds lined with a cuboidal or columnar epithelium and numerous acidic mucous secretory cells. The stomach has muscularis, which consists of longitudinal and circular muscular layers; its submucosa and muscularis mucosae are well developed. Only primary folds are present in the stomach. Microvilli are present in the epithelial layer. The stomach has a well-developed gastric gland and relatively more secretory granules. Mucosal epithelium of the pyloric caeca is composed of neutral mucous secretory cells and columnar epithelium with developed microvilli in the apical portion. Using the morphological and histological features, the intestine may be divided into anterior, mid and posterior parts. It has an advanced striated border and abundant acidic mucous secretory cells and some neutral mucous secretory cells. The mid intestine has more abundant acidic mucous secretory cells than the anterior and posterior parts. A thick longitudinal muscle is formed in the intestine and its thickness is progressively increased towards the posterior end.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.44 no.1
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• pp.45-49
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• 2011

As a first step toward identifying a new method for testing sea snail tissue for toxins, and thus prevent food poisoning due to the ingestion of contaminated snails, we measured the tetramine [$(CH_3)_4N^+$] contents of sea snails from the Korean coast using both liquid chromatography-tandem mass spectrometry (LC-MS/MS) and ion chromatography. For tetramine tested, good linearity ($r^2$ = 0.9996) was observed between the amounts in the injected samples and the peak areas of standard toxins, which ranged from 0.1 to 100 ng. The recovery (%) of tetramine from spiked tissue and mid-gut gland samples ranged from 84.0 to 95.3%. The quantitative results for tetramine using this method were in good agreement with the theoretical values. LC-MS/MS has both high sensitivity and selectivity, which makes it possible to measure trace quantities of tetramine in samples.

• International Journal of Industrial Entomology and Biomaterials
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• v.16 no.1
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• pp.21-27
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• 2008

The expression of heat shock protein genes (Hsp 70, Hsp 40, Hsp 20.8 and Hsp 20.4) against thermal stress in silkworm Bombyx mori was performed through semi-quantitative reverse transcriptase-polymerase chain reaction (RT-PCR). Upon exposure of silkworm to two temperature regimes ($38^{\circ}C$ and $42^{\circ}C$), significant change in the expression of Hsp gene was observed as compared to the control. Hsp 70 and Hsp 40 showed increased expression than the small heat shock protein genes Hsp 20.8 and Hsp 20.4. The Hsp 70 showed increased expression during the recovery period as compared to 1 hr thermal treatments ($38^{\circ}C$/1 hr and $42^{\circ}C$/1 hr). Whereas, Hsp 40, Hsp 20.8 and Hsp 20.4 genes showed higher expression level at initial stages that later gradually decrease during recovery period. Tissue specific expression of Hsp 70 showed variation in the level of expression amongst the tissues. The mid gut and fat body tissues showed higher expression than the cuticle and silk gland tissue. The Hsp 70, Hsp 40 gene expression was analyzed in thermotolerant (Nistari) and thermo susceptible silk worm strain (NB4D2) and results showed significant variation in their expression level. The Nistari showed higher expression of Hsp 70 and Hsp 40 genes than the NB4D2. These findings provide a better understanding of cellular protection mechanisms against environmental stress such as heat shock, as these Hsps are involved in an organism thermotolerance.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.32 no.5
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• pp.642-648
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• 1999

The digestive tract of the black sea bream, Acanthopagrus schlegeli is composed of esophagus, stomach, intestine, anus and four or five pyloric caeca. Pyloric caecum is a blind sac in shape and originated from pyloric portion of the stomach. Relative length of But (RLG), that is length of digestive tract to standard length, is 1.04 (n=10). Histological layer of the digestive tract is composed of serous membrane, muscular layer, undeveloped submucosal layer and mucosal layer. The mucosal folds of the esophagus are regular branched form, Esophageal muscularis mucosae is well-developed. Mucosal epithelial layer is composed of cuboidal or columnar epithelium and mucous secretory cell. Microvilli are absent in the free surface of mucosal epithelium. The mucosal folds of the stomach are regular unbranched form. The stomach has a well-developed muscular layer and muscularis mucosae. Microvilli are present in the free surface of mucosal surface epithelium. The fundic portion of the stomach have a well-developed gastric gland and more numerous secretory granules than the other parts. The mucosal folds of the pyloric caeca and the intestine are irregular branched form, Intestine is divided into the anterior, mid and posterior intestines with length of mucosal folds and histological features, Posterior intestine has a more developed striated border and goblet cells than the other parts. Mid intestine has a more abundant absorptive cells than the other parts in the intestine and pyloric caeca.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.3 no.1
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• pp.27-32
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• 1970

A study on the purification of the surf clam Mactra Sulcataria REEVE for the remove of sand and fecal piles was conducted in the laboratory. The sand was mostly distributed around the inhalent and exhalent siphon, mantle and gill, and were also distributed in the digestive tract including the mid-gut gland. The sand particles in the digestive tract were extremely small and their sizes were about $180\times10\mu\;to\;550\times200\mu$. It could be seen that there was little, if any, difference in the rate of sand removal when either the hanging Purification method was used or the method of laying the surf clams in thick or thin layers on the bottom of the experimental vessel was used. The surf clam removed about $50\%$ of its sand during the first hour of purification. The weight of the removed sand and fecal piles on a dry basis reached a constant value after 22 to 26 hours of purification. After 42 hours of Purification, no sand could be seen in the fecal piles. The surf clam removed the sand in its body more rapidly when it was in sea water with the pH of 8.75 than when it was in natural sea water. Also high temperature had a much greater depressing effect upon the removal of sand In the surf clam than did natural sea water. Also low salinity had greater accelerating effect upon the removal of sand in the body than did natural sea water. However the surf clam died when the salinity was $8.19\%_{\circ}$.