60Co 감마선 조사에 따른 속성장 및 환경내성에 강한 둥근전복과 오분자기의 신품종 개발에 관한 연구

Abstract

Climate change by global warming has raised the surface temperature of South Korea up by 1.03oC for the last 40 years, which is the fastest rate in the world. Furthermore, the rise of temperature in the sea is also found more obviously than ever. The rise causes the lead to subtropical climate. As evidence, it has been observed that butter fish (finny tribe in the Pacific) was caught in the net on Korean Peninsula. More fishes that have origin in subtropical climate regions and turbulence kind are captured. Furthermore, mitra squid Loligo chinesis, which used to be caught during July and August, is now caught on September. Judging from these, considerable changes are taking place in marine ecology. The rise of water temperature works as a physical and chemical stress factor to marine life. Particularly on abalone which is one kind of Gastropoda, the rise has a great impact because the species is limited to mobility and thus has very weak resistance to environmental change. Therefore, National Fisheries Research and Development Institute (NFRDI) crossbred male Haliotis discus hannai with female Haliotis sieboldii in 2004, both of which grow fast and are firmly resistant to environmental change, in an attempt to develop an ew species that is resistant to sudden change in environment. The developed species was sea Haliotis discus hannai. Sea Haliotis discus hannai grows 20% faster thanHaliotis discus hannai and as fast as Haliotis sieboldii. In addition, it was found that sea Haliotis discus hannai has higher level of resistance to low water temperature(7℃) and high temperature (28℃) than Haliotis discus hannai in water temperature resistance test. For breeding methods, there are hybrid breeding, selection breeding and mutation breeding. NFRDI used hybrid breeding to develop an abalone that grows fast and has high resistance. Mutation breeding processes organism with radiation and chemicals because mutation takes place very rarely in organism. And mutants are selected from their posterior filial generation. When radiation is applied to it, the method is called radiation breeding. When exposed to radiation, organism is mutated by the damage to part of its chromosome and DNA, so that its information signaling system is confused. Mutants are generated from the cells in which such change brings about. Radiation breeding method is a very excellent technique in developing new breeds and creating useful genetic resources. The method has steadily produced good outputs for about 70 years since 1930s. Currently about 2,600 mutated species are registered in FAO-LAEA database (Kim, 2008). After the Convention on Biological Diversity, securing biological genetic resources was considered to be the base of national competitiveness. In this respect, we can say that it is urgent to secure source technologies related to new agriculture biotechnologythat uses radiation and biotechnology. The merits of radiation breeding include advantage of developing one or two genetic traits, excellence in improving inferior traits of a superior breed, more yields, better quality and higher resistance to harmful insects than those of existing breeds. Unlike GMO that artificially incorporates foreign genes into existing breeds, radiation breeding has been verified for its safety. It has been widely used in developing crops such as rice and bean, flowers like rose and chrysanthemum and fruit trees. In addition, radiation breeding requires less developing cost than other breeding technologies. Furthermore, radiation breeding can be applied to plant breeds, to where hybrid breeding can't be applied or for which GMO breeding method hasn't been established. Therefore radiation breeding can be expected to develop native plants and foreign plant breeds that South Korea lacks, contributing to expanding the resource of breeds (genetic resources). (Kang, 2007) To determine the impact of low-dose irradiation with gamma ray on Haliotis discus discus, the growth was observed through the physiological change and breeding. The death of parent abalones by irradiation with gamma ray has not occurred in all the experimental plots from the domestication period to the egg collection period. However, it was observed that the activity decreased in some of theparent shellfishes of the 20Gy and 25Gy experimental plots. It seems that this phenomenon was due to the damage of DNA caused by irradiation with gamma ray. Also, it is estimated that this phenomenon was caused because it would consume energy to restore the damage of DNA. As for those fertilized eggs that had been obtained by the artificial egg collection, the presence of mutation of fertilized eggs were observed under the microscope every hour after transferring the seawater of 1L that contained the fertilized eggs for each experimental plot. The mutation of fertilized eggs has not occurred at the control plot, 10, 15 and 20Gy; however, it has occurred at the 25Gy experimental plot. In the developmental process of fertilized eggs, the form of mutated eggs was observed at the 15, 20 and 25Gy with the exception of the control plot and 10Gy, whereas the occurrence has not progressed further. The extent of occurrence delay could be related to the spawning of nonfertilized eggs in accordance with gamma ray amount and the sex maturity ratings of abalone for irradiation with gamma ray. Also, this experiment could verify the increase in the probability of mutation for the fertilized eggs by the irradiation; however, it could not verify that the morphological mutation of fertilized eggs was related to the mutation of Juvenile abalone. To measure the hatching rate and attachment rate, the fertilized eggs were measured as they were housed and bred in the water tank that had been set for each experimental plot. In the case of hatching rate, it was found to be approximately 50 percent at the control plot and the experimental plots of 10 and 15Gy; however, it was found to be approximately 30 percent at the experimental plots of 20 and 25Gy dose. This study produced F1 Juvenile abalone by irradiating abalone with gamma ray for the first time in South Korea and even applied for the relevant patent. Also, the analysis on the remaining amount in Juvenile abalone that had been produced after being irradiated with gamma ray was performed. As for the production of genes, the oligonucleotide primer as to Myostatin, Caspase-8, HSP-70 mRNA that had been registered at NCBI in relation with abalone were produced and synthesized, and then the expression level and so on were investigated. As a result, no remaining amount of gamma ray was detected in all the experimental plots of 10Gy, 15Gy and 20Gy, which had been irradiated with gamma ray. It is believed that there would be no residual substance because gamma ray was a light rather than a substance residing in the body. The expression of Caspase-8 mRNA that was immune gene expression in accordance with irradiation with gamma ray was found in all the experimental plots. Also, it was possible to confirm that the expression level was higher in the 20Gy experimental plot than the other experimental plots. It is believed from these results that theexperimental plot that had been irradiated with gamma ray 20Gy would have a better environmental tolerance. The expression of Myostatin mRNA that was growth gene was not found in the control experimental plot; however, it could be confirmed that it was expressed at a high level in the gamma ray 20Gy experimental plot. It is believed from these results that a rapid growth of abalone development would be possible by irradiation with gamma ray of 20Gy. Moreover, it could be confirmed that the expression of heat shock protein (HSP 70) mRNA, which was a stress protein, was found in the 20Gy experimental plot for water temperature and the 20Gy experimental plot for salinity. It is believed that the experimental plot that had been irradiated with gamma ray of 20Gy had a better environmental tolerance at 30℃ as for the stress of water temperature, whereas the experimental plot that had been irradiated with gamma ray of 20Gy at 25psu as for the stress of salinity had a better self-immune mechanism ability. At last, it was confirmed that marine organisms had a good result by using gamma ray as terrestrial organisms. Thus, it would be required to conduct a study in breeding and immune function for other more breeds. It should be necessary to conduct more diverse experimental analysis and long-term studies for comprehensive review on various changes.