본 연구는 질적 연구방법을 적용하여 유치원 교실 내에 개구리를 기를 수 있는 자연관찰영역을 구성하여 일상적, 지속적으로 개구리와 만나며 보살펴 주고 기르는 과정에서 유아들이 어떠한 자연친화경험을 하는지 알아보는데 목적이 있다. 이러한 목적에 따라 충청북도 청원군에 소재한 M초등학교병설유치원의 만 3, 4, 5세 혼합연령으로 구성된 유아 7명을 연구 참여자로 선정하여 참여관찰을 통한 녹화자료들의 전사와 사진, 연구자의 기록 및 메모, 유아들의 작품 분석 등의 다양한 방법으로 자료를 수집하였다. 수집된 자료의 분석 결과, 개구리 기르기 활동에 참여한 유아들의 경험은 「개구리에게 느끼는 두려움」, 「개구리와 관계 형성하기」, 「개구리를 애정으로 돌보기」, 「호기심에서 생긴 궁금증 해결하기」로 나타났다.

We investigated the toxic effects of difenoconazole on the development in the African clawed frog, Xenopus laevis. To test the toxic effects, frog embryo teratogenesis assays using Xenopus were performed. Embryos were exposed to various concentrations of difenoconazole (0-30 μM). LC100 for difenoconazole was 30 μM, and the LC50 determined by probit analysis was 27.19 μM. Exposure to difenoconazole concentrations ≥5 μM resulted in 10 different types of severe external malformation. Histological examinations revealed dysplasia of the eye, heart, liver, somatic muscle, and swelling of the pronephric ducts. The tissue-specific toxic effects were investigated with an animal cap assay. Blood cells were normally induced at a high frequency by mSCF and activin A. However, the induction of blood cells was strongly inhibited by the addition of difenoconazole. Electron micrographs of tested embryos showed the degeneration of somatic muscle and the shrinkage of microvilli on pronephric duct. The gene expression of cultivated animal cap explants was investigated by reverse transcriptase-polymerase chain reaction (RT-PCR). It revealed that the expression of the blood-specific marker(β -globin Ⅱ) and muscle-specific marker (XMA) were more strongly inhibited than the neural-specific marker(XEn2) by the addition of difenoconazole.

We investigated the toxic effects of tebuconazole on development in the African clawed frog, Xenopus laevis. To test the toxic effects, frog embryo teratogenesis assays using Xenopus were performed. Embryos were exposed to various concentrations of tebuconazole(0-100 μM). LC100 for tebuconazole was 100 μM, and the LC50 determined by probit analysis was 82.35 μM. The exposure to tebuconazole concentrations ≥40 μM resulted in 11 different types of severe external malformations including gut dysplasia. Histological examinations revealed various dysplasia in the eye, heart, liver, intestine, somatic muscle, and in the pronephric ducts. The tissue-specific toxic effects were investigated with an animal cap assay. Blood cells are generally induced at a high frequency by the combination of mSCF and activin A, however, the induction of blood cells was strongly inhibited by the addition of tebuconazole. Electron micrographs of tested embryos showed many of multivesicular bodies and dysplasia of photo-receptive cell, however, the somatic muscle degeneration was not severe. The gene expression of cultivated animal cap explants was investigated by reverse transcriptase-polymerase chain reaction and revealed that expression of the blood-specific marker, β globin Ⅱ and muscle-specific marker, muscle actin were more strongly inhibited than the neural-specific marker, XEn2.

We investigated the toxic effects of carbaryl on early embryo development in the African clawed frog, Xenopus laevis. To test the toxic effects, frog embryo teratogenesis assays using Xenopus were performed. Embryos were exposed to various concentrations of carbaryl (5∼320 μM). LC100 for carbaryl was 320 μM, and the LC50 determined by probit analysis was the concentration of 235.68 μM. Exposure to 160 μM of carbaryl resulted in 10 different types of severe external malformations. Histological examination revealed dysplasia of the eyes, heart, guts, somatic muscle, dorsal, liver, blood vessel and swelling of the pronephric ducts. Malformation of neural tissue and brain was not severe even in the high dose of carbaryl. Benzidine blood stain showed distinct inhibition of inducing erythrocytes in embryos and animal cap explants. Electron micrographs of embryo revealed retinal detachment, loose photoreceptor lamella and the degeneration of sarcomeres in the carbaryl-treated group. The mitochondrial degeneration was also observed in the test group.