^(60)Co 방사선 조사가 전복치패 및 넙치 수정란에 미치는 영향에 관한 연구

Abstract

The present study was carried out to identify physiological changes such as blood components or antioxidant enzymes, protein levels, viability, and hatching of egg after radiation exposure on the fertilized egg of Haliotis discus hannai, Haliotis discus discus, and Paralichthys olivaceus. In order to evaluate the effect of low radiation on the fertilized egg of H. discus hannai and Paralichthys olivaceus, the radiation exposure was performed at the level of 0, 0.2, 0.4, 0.8, 1, 2, 4, 8, 10 and 20 Gy. The physiological changes of H. discus hannai was analyzed at 1, 3, 6, 12, 24, 48, and 72 hours after irradiation, while analysis of the egg of Paralichthys olivaceus was performed by development stages. The experiment of high radiation on H. discus discus was tested to determine LD50 and the physiological responses. This exposure was performed at the level of 0, 50, 100, 200, 400, and 800 Gy, the analysis of irradiated groups was accomplished at 0, 1, 2, 3, and 4 weeks after the exposure. Low level of irradiation on H. discus hannai showed that the dropping level of lymphocytes at the early stage after irradiation has recovered to the normal. Distinctive protein was only expressed the control and 0.2 Gy-irradiated group for 21 kDa protein and the 0.2 Gy- and 0.4 Gy-irradiated group for 31 kDa protein. The level of antioxidant enzymes increased directly after irradiation, the value was reduced gradually until the end of experiment. Similarly, the expression of HSP 70 mRNA was decreased the experiment groups except 10 Gy-exposed group. As result of a long-term breeding of H. discus hannai after irradiation, an increase of growth was not determined. However, the 20 Gy-irradiated group has shown a remarkable delay of growth. Determination of LD50 and physiological changes for high dose of irradiation on H. discus discus was determined that irradiation-induced decline of circulating lymphocytes was linked to death. Antioxidant enzymes has decreased gradually until the death, while the expression of HSP 70 mRNA has increased gradually. Finally, the LD50 of H. discus discus was revealed 30 ~40 Gy. The physiological changes of the fertilized egg of Paralichthys olivaceus after low irradiation was determined that LD50 until larvae was about 8 Gy. Irradiation of 8 ~ 20 Gy has induced a delayed cell cycle arrest. This is going to distinguish a difference of protein expression on the irradiated egg. As a result of the changes irradiation, the eggs was died after all. The genes related growth was reduced at the early phase after irradiation, levels of genes were rising to larvae stage. These data has shown that radiation hormesis was not determined in H. discus hannai, high dose of radiation was influenced a growth limitation during long-term cultivation. High irradiation on the eggs of Paralichthys olivaceus was induced cell cycle arrest and was linked to death. However, it is necessary to evaluate a hormesis effect of irradiation on the eggs of Paralichthys olivaceus. This study was determined LD_(50) as an important point in radiation induced mutation breeding of valuable breeding species. High dose of irradiation was changed levels of DNA, RNA, and enzymes on the irradiated individuals, it is linked to difference of protein, cellular function, and individual death finally. To obtain the practical benefits through radiation applied breeding for marine organism, data for various species, research for radiation hormesis, approach for overall evaluation, determination of generation effects, and long-term observation need to be further evaluated.