• Korean Journal of Ichthyology
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• v.31 no.3
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• pp.131-140
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• 2019

This study is to observe species identification and early life history of Gnathopogon strigatus and to use it as a basis for taxonomic studies and conservation of species. For the experiments, the mature adults were collected at the Wang-suk Stream located in Namyang-ju city, Gyeong-gi Province and eggs were artificially fertilized by the wet method in the laboratory. The shape of the fertilized egg was globular, adhesive, opaque white in color and had no oil globules. The fertilized egg was 1.66~1.88 mm (average 1.76 mm, n=30) in diameter. The blastular stage occurred at 3 hours 05 minutes after fertilization and the gastrular stage was detected at 8 hours 30 minutes after fertilization. The embryo began to hatch about 54 hrs after fertilization under water temperature of $23{\pm}1^{\circ}C$ and the newly hatched larva (yolksac larva) were 4.1~4.7 mm (mean 4.4 mm, n=20) in total length (TL). The fourth day after hatching, the postlarva were 5.4~5.9 mm (mean 5.6 mm, n=20) in total length, their york sacs were completely absorbed and Start eating Artemia sp. Ten days after hatching, flexion larva were begins Notochord flexion were 7.5~8.6 mm (mean 8.1 mm, n=20) in total length. Sixteenth day after hatching, postflexion larva were complete Notochord flexion were 8.2~9.7 mm (mean 9.1 mm, n=20) in total length. At thirty-eight days after hatching, Juvenile were arrive integer all fin rays and similar to those of adults were 11.3~15.5 mm (mean 13.3 mm, n=20) in total length.

• Bulletin of the Korean Chemical Society
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• v.29 no.6
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• pp.1179-1184
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• 2008

Commercial nanometer sized silver is widely used for its antibacterial effect; however, nanoparticles may also have ecotoxicological effects after being discharged into water. Nanometer sized silver can flow into aquatic environments, where it can exert a variety of physiologically effects in living organisms, including fish. The present study aimed to investigate the effect of nanometer sized silver on the development of zebrafish embryos, analyze the properties of commercial nanometer sized silver and define the toxicity relationship between embryogenesis and hatched flies. The commercial nanometer sized silver was analyzed in the $Ag^+$ ion form. The hatch rate decreased in the nano-silver exposed groups (10 and 20 ppt); furthermore, the hatched flies had an abnormal notochord, weak heart beat, damaged eyes and curved tail. The expression of the Sel N1 gene decreased in the nano-silver exposed groups, and the catalase activities of the exposed groups increased relative to those in the control group. Therefore, the $Ag^+$ ions in commercial nanometer sized silver could accumulate in aquatic environments and seriously damage the development of zebrafish embryos.

• The Korean Journal of Cytopathology
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• v.12 no.2
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• pp.105-110
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• 2001

Chordoma is a rare, clinically and morphologically well characterized tumor, which arises from remnants of the notochord, The majority(60%) occurs in the sacrococcygeal region, with 25% in the clival legion, and 15% in the spine. Although most chordomas do not develop metastasis, the long term prognosis is very poor due to local progressive tumor growth and tendency to recur if incompletely excised. The chordoma has characteristic cytologic features which make a preoperative diagnosis possible. We reviewed the cytologic findings of five patients with chordoma(one oropharynx, two clivus, and two sacrum). The patients were three male and two female, aged from 29 to 77 years(mean 60). Of five chordomas, there were local recurrences in two cases and metastasis of lymph node In one case. Four were FNA smears and one was squash smear taken from intraoperative consultation. All five cases show similar cytologic features. The dominating tumor cells were large with round nuclei and pale-stained vacuolated cytoplasm. The small round uniform cells and short spindle-shaped cells were frequently noted. The cells were surrounded by myxoid or mucoid matrix. The chordoma has characteristic cytologic features which make a preoperative diagnosis possible.

• Toxicological Research
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• v.11 no.1
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• pp.37-42
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• 1995

Effect of cadmium on the early amphibian development was analyzed through FETAX (Frog Embryo Teratogenesis Assay: Xenopus). Embryos manifested concentration-dependent mortality and realformations; shortage of anterior-posterior axis gut realformation, ocular anomalies, bent notochord, misshapen dorsal fin, and derreal blisters. The treatment with 1.5ppm cadmium solution caused 100% mortality and concentration of lppm did not kill the embryos that caused 100% anomaly. The teratogenic index (TI = LC50 /EC50) was 2.8 indicating that $CdCl_2$ is teratogenic for Xenopus laevis. Embryos that were pulsetreated with at early to late blastula stage (St. 3-9) and mid to late blastula stage (St. 6-10) showed relatively strong resistance to cadmium, but the embryos treated at gastrula stage (St. 10-13) showed high mortality. And the embryos treated at tailbud stage (after St. 25) showed highest mortality of any other early stages. Effects of temperature were studied through pulse- treatment during gastrula stage at $20^{\circ}C$ and $30^{\circ}C$. The embryos treated with 7.5ppm at $30^{\circ}C$ and 15ppm at $20^{\circ}C$ caused 100% mortality respectively, indicating that higher temperature had more severe toxic effect. One of the most peculiar effect of cadmium at gastrulation was distortion of the tail. The probable cause of toxic effect of Cd was discussed.

• Archives of Plastic Surgery
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• v.37 no.5
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• pp.702-704
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• 2010

Purpose: Chordoma is a rare primary osseous tumor arising from the remnants of the primitive notochord. It occurs once in 2,000,000. It is characterized by its slow growth, high frequency to invade destroy bone by direct extension. We experienced giant sacral chordoma and reconstructed with gluteal advancement flap. Methods: A 52-year-old woman presented with a 2-years history of gluteal pain. In the biopsy study revealed sacral chordoma. MRI study showed $13{\times}12{\times}10\;cm$ sized m0cs. We approached anterior and posterior resection and reconstructed with bilateral gluteus maximus advancement flap. Results: After the operation, blader and anal function were slightly decreased. But, 4 months later those were almost fully recovered. There was no significant complication and recurrence after 2-years follow-up. Conclusion: Chordoma is characterized by its slow growth, high frequency to invade and destroy bone by direct extension. Wide surgical resection is the only curative procedure. We report a ase of giant sacral chordoma which was successfully treated by anterior and posterior approach and reconstructed with bilateral gluteal advancement flap.

• Radiation Oncology Journal
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• v.6 no.2
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• pp.295-300
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• 1988

Chordoma is a malignant tumor arising from the primitive notochord involving the axial skeleton. It usually occurs at sacrococcygeal and besisphenoidal area but only rarely does at other vertebral areas, especially at the thoracic vertebrae. It has a slow growth rate and is locally aggressive with an extremely high rate of local recurrence. Either surgery or radiation alone often fails to cure the disease and the local failure is the main cause of treatment failure and death. Overall 5 year survival rate is less than $10\%$. Useful palliation or occasional cure can be obtained by the combination of surgery and radiotherapy. After incomplete resection, the tumor requires radiation dose of 7,000 cGy or more over 6-7 weeks for local control. Tumor regression is slow in response to irradiation and continuation of the regression for several months after completion of RT is not unusual. We report a case of chordoma of the thoracic vertebra, the site of extreme rarity, which showed good local control after partial resection and radiation therapy. He is well and alive without any evidence of recurrence after 13 months of treatment with near complete tumor regression.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.48 no.4
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• pp.498-506
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• 2015

We examined the feeding habits of larval Clupea pallasii using 148 specimens collected from December 2010 to April 2011 in the Nakdong River estuary, Korea. We found that larval C. pallasii [8.3-26.0 mm NL (notochord length)] are carnivorous, consuming mainly copepods, rotifers, cirripeds, and free-living flatworms (Macrostomida). Their diet also include small quantities of shrimp nauplii, tintinnids, cladocerans, and larval bivalves, among other food sources. To evaluate ontogenetic changes in dietary composition, we split larvae into four size groups: 8-12 mm, 12-16 mm, 16-20 mm, and > 20 mm NL. Rotifers were the most important prey items for the smallest group, but all other groups predominantly consumed copepods. The largest group frequently preyed on rotifers, cirripeds and flatworms, in addition to copepods. Larvae also showed bi-modal feeding, with peaks in the late afternoon and at midnight, wherein the mean number of prey per individual peaked at 1,800-1,900 h.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.53 no.2
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• pp.203-208
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• 2020

This study was carried out to clarify the larvae and juveniles of egg development and autonomous development of Hemibarbus longirostris from Korea, and to obtain basic data for species conservation and seed production. The shape of the egg was circular and sticky. The average size of the eggs was 2.01 mm (n=10). At 185 hours after fertilization, more than 50% of the total embryos were hatched. The newly hatched larvae had an average total length of 8.10 mm (n=5) and had egg yolk in the abdomen. At 3 days after hatching, the larvae absorbed all egg yolk was average total length 8.64 mm. On the 6 days after hatching, the caudal tip of the notochord started to curve upwards was average total length 10.9 mm. At 70 days after hatching, the average total length 37.9 mm. The number of fins was i 8-10 in dorsal fin, iii 7 in the anal fin, and ii 5 in the ventral fin.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.48 no.5
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• pp.752-759
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• 2015

We examined the feeding habits of larval Konosirus punctatus using 165 specimens collected from May to August 2011 in the Nakdong River estuary, Korea. We found that larval K. punctatus [3.9-8.4 mm notochord length (NL)] are carnivorous, consuming mainly rotifers. Their diet also included small numbers of rhizopods, tintinnids, euglenoids, copepods, larval bivalves, dinoflagellates, diatoms, and unidentified materials. To evaluate ontogenetic changes in dietary composition, we split the larvae into three size groups: < 5 mm, 5-6 mm, and > 6 mm NL. The smallest size group frequently preyed on rhizopods. As NL increased, the number of rotifers increased relative to those of rhizopods. Larvae also showed bimodal feeding for feeding incidence, with peaks in the midafternoon and at midnight, while the mean number of prey per individual peaked at 18:00-19:00 h.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.49 no.5
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• pp.642-647
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• 2016

Postlarval and juvenile anchovies Engraulis japonicus were collected using a gape net with wings in the coastal waters of Yeosu in July and August 2015, and their gut contents were analyzed. The size range of the postlarvae was 11.0-24.2 mm (notochord length) and that of the juveniles was 25.1-37.4 mm (standard length). Guts were empty in 64.5% of postlarvae and in 51.7% of juveniles. The dominant prey organisms in the guts of both postlarvae and juveniles were copepoda. Calanoida were important prey organisms for postlarvae and were dominated by nauplii of Paracalanus sp. and Calanus sp. as well as unidentified copepod naupill. Calanoida were also important in the diets of juveniles, whose gut contents were dominated by Paracalanus sp. and Cirripedia. Gut compositions were significantly different (P<0.05) among three body size levels in postlarvae and juveniles. As the body size of the postlarvae and juveniles increased, Calanoida constituted a larger proportion of the gut contents, while the proportion of copepod nauplii decreased.