• Proceedings of the Korea Society of Environmental Toocicology Conference
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• 2003.05a
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• pp.158-159
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• 2003

Fluoranthene, a common polycyclicaromatic hydrocarbon (PAH), exhibits phototoxicity which may affect aquatic organisms. The eventual goal of this study is to develop a biomarker used in monitoring abnormal behaviors of Japanese medaka (Oryzias latipes) as a model organism caused by hazardous chemicals that are toxic and persistent in the ecosystem. In this study, we investigated neural toxicity of fluoranthene in Japanese medaka (Oryzias latipes) which was correlated with its behaviors.

• Proceedings of the Korea Society of Environmental Toocicology Conference
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• 2001.05a
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• pp.131-131
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• 2001

내분비계장애물질에 대한 검색기법의 하나로 수컷 어류의 교배행위 및 생식력에 대한 in vivo 연구를 시도하였다. 수컷 송사리(Oryzias latipes)에 대표적 에스트로젠인 17$\beta$-estradiol를 2 및 20 $\mu\textrm{g}$/L의 농도로 각 노출군당 5마리씩 14일간 노출시킨 후 각 군당 임의로 2마리씩 선택하여 Prostaglandin F2$\alpha$를 주사한 3마리의 정상 암컷 송사리와의 교배행위를 비디오 카메라를 이용하여 1시간 동안 녹화하여 분석하였다. (중략)

• Environmental Mutagens and Carcinogens
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• v.16 no.1
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• pp.30-34
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• 1996

This study was performed to examine the availability of using medaka (Oryzias latipes) in teratological test. Medaka embryos were collected within 2 hours post-fertilization and cultured in petri dishes containing buffered saline until hatching. The embryos were treated with 0.56 mg/l chlorpyrifos-methyl and 10 mM methyl methanesulfonate at 20 stages (about 35 hours post-fertilization). Eleven developmental features were selected and observed from 33 stages (about 9 days post-fertilization). Scoring system was developed and applicated for the measurement of potential teratological effects by the test compound. Chlorpyrifos-methyl did not induce teratological effect in medaka embryos. However, we found teratological test using medaka embryo reduced the cost, labors, period and space of experiment significantly compared with teratological study using rodents. Above findings strongly suggest that medaka embryo can be used as a lab animal model for teratogenicity test instead of rodents.

• Animal Systematics, Evolution and Diversity
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• v.13 no.1
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• pp.9-20
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• 1997

한국산 송사리 (Oryzias)속의 송사리 (O. latipes)와 대륙송사리(O. sinensis)의 집단 내 유전적 변이 및 종간 유연관계를 밝히고자 남한의 16개집단과 일본산 송사리(O. latipes) 1개 집단 등 총 17개 집단에 대한 isozyme 분석을 실시하였다. Isozyme 분석 결과 17개의 효소 및 비효소단백질에서 총 32개의 유전자를 검출한 결과, 전체 유전자중 Est-1과 Est-3 는 종 특유의 유전적 표식인자(genetic marker)였다. 송사리집단 중 진도집단의 유전적 변이 가 가장 낮았으며(Ho=0.011, He=0.043), 대륙송사리 서천집단의 유전적 변이가 가장 높았 다.(Ho=0.114, He=0.124). 한국산 송사리 11개 집단의 평균 유전적 변이 정도는 P=12.7%, Ho=0.029, He=0.042, 대륙송사리 5개 집단의 평균 유전적 변이정도는 P=26.3%, Ho=0.082, He=0.097로 각각 나타나 대륙송사리집단의 유전적 변이 정도가 송사리집단에 비해 약 2.5배 정도 높았고 일본산 송사리의 유전적 변이 정도는 P=15.6%, Ho=0.073, He=0.068로 나타났 다. 한국산 송사리와 일본산 송사리와의 유연관계는 S=0.761(D=0.243)로 나타나 유전적으로 뚜렷한 별개의 분류군으로 생각되며, 대륙송사리와 송사리간의 종간 유전적 근연치는 S=0.648(D=0.389)로 일반적인 척추동물의 종간 유전적 분화 수준을 나타냈다.

• Proceedings of the Korea Society of Environmental Toocicology Conference
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• 1999.05a
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• pp.50-50
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• 1999

• Journal of Environmental Health Sciences
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• v.31 no.3
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• pp.227-233
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• 2005

This study was conducted to determine the endorcrine disruption effects of the several major pharmaceutical residues in water using adult Japanese medaka (Oryzias latipes). Four frequently used pharmaceuticals including caffeine, ketoconazole, acetaminophen, and diltiazem were investigated for the vitellogenin(Vtg) induction in the medaka using Western blotting and ELISA. $17\beta$,-estradiol was used as a positive control. Vtg was qualified and quantified through Western blot and ELISA. Following SDS gel electrophoresis, the dominant protein band was identified to molecular weight approximately 205 kDa in whole body samples of vitellogenic female. With female medaka exposed to $17\beta,-estradiol$, no significant difference in total protein induction was noted. In contrast, three to five day exposure of male fish to $17\beta,-estradiol$ resulted in $63.07\%o$, increase of total protein comparing to that of control males (p<0.01). Vtg induction in male fish was observed with all the test pharmaceuticals: At concentrations greater than 1ppm of diltiazem, 2 ppm of caffeine, 4 ppm of acetaminophen, and 10 ppm of ketoconazole, Vtg induction was monotonously increased in a dose dependent manner. This study is one of the first reports suggesting potential endocrine disruption mechanism of common human pharmaceutical products in aquatic ecosystem. Although the effect concentrations obtained from this investigation are environmentally unrealistically high, endocrine disruption should be considered as one of the important consequences of pharmaceutical pollution in aquatic environment, and warrants due attention in future researches.

• Journal of Environmental Health Sciences
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• v.32 no.3
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• pp.227-234
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• 2006

There has been increasing concern in recent years about the occurrence, fate and toxicity of pharmaceutical products in aquatic environment. Although these compounds have been detected in a wide variety of environmental samples including sewage effluent, surface waters, ground water and drinking water, their concentrations generally range from the low ppt to ppb levels. It is therefore often thought to be unlikely that pharmaceuticals will have a detrimental effect on the environment. This study was conducted to determine the endocrine disruption effects of the several pharmaceutical residues in water using adult Japanese medaka (Oryzias latipes). The common antibiotics were used sulfa durgs (sulfamethoxazole and sulfamethazine) and tetracycline drugs (oxytetracycline and tetracycline). Positive control that was induced Vtg (vitellogenin) in male fish was used $17\beta$-estradiol. Vtg was qualified and quantified through Western blotting and ELISA. After SDS gel electrophoresis, the dominant protein band was identified to molecular weight approximately 205 kDa in whole body samples of vitellogenic female. In female medaka exposed to $17\beta$estradiol, there was no significant difference in total protein induction. In contrast, three to five day exposure of male fish to $17\beta$-estradiol resulted in more than 60.0% increase of total protein compared to that of control males (p<0.01). In case of antibiotics, female fish didn't show significant difference, but male fish was showed significant difference. In addition, Vtg induction in male fish was observed with all the test chemicals. On concentrations greater than 0.1 ppm of sulfamethoxazole, 1 ppm of sulfamethazine, 1 ppm of oxytetracycline and 20 ppm of tetracycline, Vtg induction was increased in a dose response manner. This study is one of the early reports suggesting potential endocrine disruption mechanism of antibiotic pharmaceutical products in aquatic ecosystem. Although the effect concentrations obtained from this study were high as unrealistically as in environments, it is endocrine disruption that we should be considered as one of the important consequences of pharmaceutical contamination at water environment, and warrants due attention in future researches.

• Korean Journal of Environmental Agriculture
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• v.4 no.2
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• pp.118-125
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• 1985

To establish an evaluation system of aquatic toxicity of chemicals at no-effect level, flow through and early life stage toxicity test were performed on a freshwater fish, the medaka (Oryzias latipes). The characteristics of medaka as a bioassay organism for the chronic toxicity test were discussed. Maximum acceptable toxicant concentration(MATC) of butachlor for the madaka in soft water was estimated using survival, growth, and reproduction as indicators of toxic effects. During a 3-month period, the fry of medaka were exposed to butachor concentrations ranging from 0.16 to 0.0l mg/liter and the DO concentration, temperature, and pH in the exposure chamber were measured to check the test condition. The highest concentration showed slight decrease of growth rate in medaka and reduced hatchability of spawning egg. Survival, growth, and reproductive success of adults in butachlor concentration of 0.04 and 0.01 mg/liter were not different from those of the control. The MATC was estimated to be between 0.04 and 0.16 mg/liter for medaka.

• Journal of Environmental Health Sciences
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• v.29 no.2
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• pp.7-15
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• 2003

Di-2-ethylhexyl phthalate (DEHP), is a widely used plasticizer known to be a suspected endocrine disrupter, but its exact effects on aquatic organisms are not yet known. When Japanese medaka (Oryzias latipes) were exposed from the time of hatching to 3 months of age to an aqueous DEHP solution at nominal concentrations of 1, 10, and 50 $\mu\textrm{g}$/l, DEHP treated female fish showed distinct reproductive effect. And the midge (Chironomus riparius.). an aquatic invertebrate, was exposed to DEHP to evaluate the effects on reproductive processes via sediment toxicity. The test endpoints included emergence, sex ratio, fecundity, and the viability of F1 offspring egg ropes. The result implied that the normal developmental and/or reproductive processes in C. riparius had been disrupted when exposed to DEHP, the effect also being displayed in the next generation. In summary, DEHP hinders the development of reproductive organs in the female Japanese medaka and C. riparius.

• Animal cells and systems
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• v.6 no.1
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• pp.75-80
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• 2002

A study on the effects of bisphenol A (BPA) on sex differentiation and gonadal development in medaka, Oryzias latipes, was investigated by histological examination. The fish were exposed to aqueous solutions of BPA at nominal concentrations of 50, 100, and 200 $\mu\textrm{g}$/L from newly-hatched larvae stage to 70 d. The ovaries of female fish were composed of oocytes at the chromatin nucleolus and peri-nucleolus stages at 20 d after the exposure. The testes contained a number of spermatogonia and spermatocytes at 30 d. In the process of sex differentiation. gonadal development was not different in all experimental groups until 30 d after the exposure. At 70 d after the exposure, however, advanced development of oocytes in the ovary and inhibition of spermatogenesis in the testis were observed in the BPA-treated groups compared to the non-treated controls. More females than males were identified in the 50 and 100 $\mu\textrm{g}$/L BPA-treated groups, in comparison to the 200 $\mu\textrm{g}$/L BPA-treated group and non-treated controls. Medaka exposed to 200 $\mu\textrm{g}$/L BPA were bigger compared to other experimental groups. The present study suggests that BPA may lead to problems in either mating or sexual behavior due to the difference in growth and disparity of sexual maturation between male and female fish.