• Environmental Analysis Health and Toxicology
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• v.15 no.3
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• pp.61-67
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• 2000

Toxic lesions of styrene in the Japanese Medaka (Oryzias latipes) were compared with those of styrene oxide, the active metabolite of styrene, using embryo-larval assays. The developmental stages of Japanese Medaka (Oryzias latipes) treated with both chemicals were not altered and progressed normally. However, styrene oxide was more toxic than styrene in terms of causing death and lesions . High concentrations of styrene (higher than 4.9 ppm) and styrene oxide (higher than 2.4 ppm), resulting in more than 50% mortality, caused similar lesions of cardiovascular system, craniofacial bone formation and spinal deformities, although a number of lesions were not observed by both chemicals . In the group treated with styrene, eyeball sizes and intereye distances were reduced, while, in the group treated with styrene oxide , the eyes and eye cups were not developed and two eyes were sometimes fused. In addition, styrene oxide caused the lesion which involved the posterior brain and brain stem were herniated through the spinal cord . The noticeable difference of toxic symptoms between these two chemicals was the time of onset. Toxicities of cardiovascular system and craniofacial bone formation appeared on day 3 of development in styrene oxide treated group, but, styrene treated group staned to show hemorrhages on day 3 and the craniofacial malformation were appeared on day 5, These differences between two chemicals may be due to the metabolism of styrene to styrene oxide, the reactive intermediate.

• Journal of Environmental Health Sciences
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• v.33 no.6
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• pp.513-516
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• 2007

This investigation was intended to find out the estrogenic effect of chlortetracycline (CTC) on vitellogenin induction in adult male Japanese medaka (Oryzias latipes). Vitellogenin (Vtg) produced in male fish has been used to as one of a biomarker of endocrine disrupters. The positive control was $17{\beta}-estradiol$ (E2) that induced Vtg in male fish. As a result, male and female fish were exposed to 0.1, 1, 10 and 100 ppm of CTC. Western blot results showed approximately 205 kDa, that is similar to myosin at high molecular weight range Sigma maker. Vtg band was showed fainted to 10 and 100ppm for chlortetracycline. Vtg concentration of CTC was qunatified by total protein quantification and ELISA. Exposure of the male fish to CTC of 0.1, 1, 10 and 100 ppm produced Vtg concentrations of 0.24, 0.12, 7.61 and 40.02%o, respectively, that value was elevated than control male fish (0.14%o). CTC exerted as a Vtg inducer in male fish from 10 ppm, but it was a reducer in female fish from 0.1 ppm level. The results say that vitellogenin induction patterns alter in male medaka treated with CTC, and that CTC may caused endocrine disruption in fish.

• Journal of Environmental Health Sciences
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• v.33 no.3
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• pp.207-210
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• 2007

The study was designed to determine the estrogenic effect of some penicillins on endocrine function in adult Japanese medaka (Oryzias latipes). Vitellogenin (Vtg) produced in male fish has been used for a biomarker to study endocrine disrupters. $17\beta-estradiol\;(E_2)$ was used a positive control that was induced Vtg in male fish. Result of total protein qantification and ELISA for female and male fish were exposed to $17\beta-estradiol$ 10ng/ml for $3\sim5$ days. As a result, male fish exposed to amoxicillin respectively appeared 0.75, 0.23, 8.21 and $9.36\%_{\circ}$ of 1, 10, 100 and 1000 ppm respectively, that value was elevated compared with control male fish. Male fish exposed to ampicillin respectively appeared 1.85, 4.68, 0.85 and $39.59\%_{\circ}$ of 1, 10, 100 and 1000 ppm respectively, that value was elevated compared with control male fish. This study is one of the first reports suggesting potential endocrine disruption of some penicillins in aquatic ecosystem. These results suggest that vitellogenin and estrogen receptor induction patterns alter in male medaka treated with selected estrogenic compounds, and that these results may be useful molecular biomarkers for screening estrogenic EDCs (endocrine-disrupting chemicals) in the shortest possible time.

• Journal of Life Science
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• v.23 no.3
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• pp.333-340
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• 2013

This study was performed to determine whether stem bark extract containing saponin of Albizzia julibrissin in the diet influences gonadal maturation and spawning in medaka (Oryzias latipes). The crude extraction containing saponin (HaBC) was partially purified from n-BuOH extraction of A. julibrissin stem bark by Diaion HP-20, Silica gel and Sephadex LH-20 chromatographies. We fed diets supplemented with HaBC to medaka. We then studied the effects of the HaBC supplement on the suppression of gonadal maturation and spawning in female medaka that were reared in aquaria with recirculation systems. In the experiment with immature female medaka, the periods of initiation of gonadal maturation and spawning were delayed in the fish that were fed diets supplemented with at least HaBC 20 mg/g-feed. In the experiment with mature female medaka, the fish that were fed diets supplemented with at least HaBC 20 mg/g-feed had lower GSIs than the control diet group did. The results showed that the growth of the immature medaka was not correlated with the amount of supplementation of HaBC in the diet. However, the condition factors (CF) in the medaka that were fed diets supplemented with at least HaBC 20 mg/g-feed were higher than in the medaka fed on the control diet. We concluded that extracts containing saponin from the stem bark of A. julibrissin have the potential to inhibit gonadal maturation in female medaka, but they did not act as growth stimulation. Further studies are required to determine the mechanism of the action.

• Proceedings of the Korea Society of Environmental Toocicology Conference
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• 1997.12a
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• pp.114-114
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• 1997

• Molecular & Cellular Toxicology
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• v.3 no.sup4
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• pp.33.2-33.2
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• 2007

• Proceedings of the Korea Society of Environmental Toocicology Conference
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• 2004.05a
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• pp.77-77
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• 2004

• Proceedings of the Zoological Society Korea Conference
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• 1997.10b
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• pp.150.1-150
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• 1997

• Proceedings of the Korean Society of Toxicology Conference
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• 2001.05a
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• pp.135-135
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• 2001

Mating behavior and reproductivity of male fish were studied as an in vivo screening method of endocrine disruptors. Male medaka (Oryzias latipes) were exposed to 17$\beta$-estradiol at nominal concentrations of 2 and 20 $\mu\textrm{g}$/L for 14 days.(omitted)

• Toxicological Research
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• v.17 no.2
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• pp.139-142
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• 2001

Sexual behavior and reproductivity of male fIsh were studied as an in vivo screening method of endocrine disruptors. Male medaka (Oryzias latipes) were exposed to 17$\beta$-estradiol at nominal concentrations of 2 and 20 $\mu\textrm{g}$/l for 14 days. After exposure of the chemical, sexual behavior between male medaka and normal female which were injected with prostaglandin $F_{2\alpha}$ just before the test, was analysed by using video camera for one hour. Normal control male showed courtship dancing such as following, guarding, dancing and crossing while 17$\beta$-estradiol treated male did not show any type oj courtship dancing. Furthermore, fecundity and fertility were significantly decreased in the treated group. It was suggested that analysis of sexual behavior could be a useful endpoint for the screening of the endocrine disruptors.