• Korean Journal of Environmental Biology
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• v.31 no.4
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• pp.340-346
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• 2013

We have confirmed the first case of mass mortality which occurred in the wild populations of larval toad, Bufo bufo gargarizans during 2007~2009 at Mangwel pond, which is a long time breeding site, and is located at the south eastern area in Daegu. We have investigated through microbiological tests the cause of mass decease of the larval toad, and detected numerous bacteria from the intestine by histological examines and cultures. The pathogen isolated from the infected larval toads has been identified as Aeromonas hydrophila, which is widely distributed in aquatic environment. However, this phenomenon of mass lethal pattern of the larval toad disappeared at the breeding pond after maintaining better water levels and low temperature in spring during breeding season in 2010. We propose that the high temperatures during the 2007~2009 breeding season resulted in lower water levels and drier conditions leading to explosive propagation of A. hydrophila in the pond which impacted the larval toad's immune function.

• Korean Journal of Environment and Ecology
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• v.30 no.4
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• pp.705-711
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• 2016

In this experiment, embryos of Asian toad, Bufo gargarizans, were investigated to evaluate toxicity of chemicals along FETAX(Frog Embryo Teratogenesis Assay-Xenopus) protocol. Asian toad, Bufo gargarizans, embryos incubated and investigation of Zn and Benomyl effect by probit analysis. As a result, depends on the concentrations of Zn and Benomyl, mortality and malformation rates were increases and larval body length were decreased. The teratogenic concentration($EC_{50}$) of Zn and Benomyl were 2.3, $1.0mg/{\ell}$, respectively and the embryo lethal concentration($LC_{50}$) Zn and Benomyl were 10.3, 6.9, respectively. The teratogenic index(TI) were 4.4 in Zn and 6.7 in Benomyl, thus showed teratogenicity in embryonic development of B. gargarizans. These results reveal that Zn and Benomyl in this experiment suppressed the development of embryos at relatively low concentration. Much of B. gargarizans embryos can be secured, and easy to incubate. In addition, mortality, malformation ratios, malformation patterns and growth rates are similar to the results from the other assay systems. Therefore, the B. gargarizans embryo teratogenesis assay system could be a useful tool to evaluate toxicity of pollutants in environment.

• Korean Journal of Environment and Ecology
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• v.34 no.3
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• pp.207-215
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• 2020

In this experiment, investigated toxicity evaluation of chemicals using Asian toad embryos, along FETAX(Frog Embryo Teratogenesis Assay-Xenopus) protocol. Asian toad, Bufo gargarizans embryo incubated and investigation of Benomyl(Germicide), Carbofuran(Insecticide) and Thiobencarb(Herbicide) effect by probit analysis. As a result, depends on the concentrations of Benomyl, Carbofuran and Thiobencarb, along mortality and malformation rates were increases and larval body length were decreased. The teratogenic concentration(EC₅₀) of Benomyl, Carbofuran and Thiobencarb were 1.03, 8.74, 4.98mg/ℓ, respectively. And when exposed to Benomyl, larvae responded most sensitively to malformations. Embryo lethal concentration (LC₅₀) Benomyl, Carbofuran and Thiobencarb were 7.26, 560.72, 16.87mg/ℓ, respectively. And Benomyl were at the lowest concentration of lethal the embryos. The teratogenic index(TI) were 7.05 in Benomyl, 64.16 in Carbofuran and 3.39 in Thiobencarb, thus TI values were above 1.5, which is the criterion of teratogenicity. Three of the pesticides used in this study were considered to be a teratogenic substances and Carbofuran was the most potent teratogen. And more specific researches are needed to investigate the effects of pesticides on the embryo development of toads and amphibians and their mechanism.

• The Korean Journal of Zoology
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• v.29 no.4
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• pp.261-271
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• 1986

The cutaneous xanthophore differentiation from larvae to adult in Bombina orientalis-the Korean fire bellied toad-is studied with light and electron microscopes. General structure of adult xanthophore which is composed of many pterinosomes and a small quantity of carotenoid vesicles is forming chromatophore complex with other dermal pigment cells. And the cytoplasmic process of xanthophore is distributed just beneath the basement membrane. The first differentiated xanthophore is originated from both rER rich cells and Golgi complex rich cells before and after the feeding larval stage. Formation of the pigment granule is proceeded gradually along the sequental metamorphic stages. After the metamorphosis, rapid multiplication of pterinosome is observed and enlargement of carotenoid vesicle is appeared after hybernation. These pigment granules are seen several structures by the differentiated level.