Genetic transformation is a powerful biotechnology for introducing novel genes into economically important plants from distantly-related plants or even unrelated species such as microbes and animals.This feat is impos...Genetic transformation is a powerful biotechnology for introducing novel genes into economically important plants from distantly-related plants or even unrelated species such as microbes and animals.This feat is impossible to be achieved by conventional breeding techniques.Development of transgenic plants has been a controversial subject since 1971 when the first genetically modified organism（GMO）was developed（James and Krattiger1996）.展开更多
The channel catfish Ictalurus punctatus was first introduced from the United States to the Krasnodar region of Russia 1972-1979, and it was introduced into Georgia during 1976-1978. Ecological and economic studies of ...The channel catfish Ictalurus punctatus was first introduced from the United States to the Krasnodar region of Russia 1972-1979, and it was introduced into Georgia during 1976-1978. Ecological and economic studies of channel catfish were initiated along with the acclimatization and naturalization of this new species. Channel catfish were initially reproduced and reared in the Japan aquaculture fish farm ponds. Offspring from these ponds were used to stock other ponds, industrial fish farms and natural water bodies （lakes） where natural populations were formed. The climatic conditions of Georgia are close to the natural habitat of channel catfish. The number of days with water temperature higher than 20 ℃ is about 120-140, and the accumulated heat reaches up to 2,400-2,792℃. The purpose of targeted acclimatization was for the development of aquaculture-commercial production and recreational fisheries. During the process the method of staged radial acclimatization was applied, which initially included breeding and growing of fishes in aquaculture farms. Offspring produced in hatchery were then introduced into new fish farms and water bodies to develop populations. The water temperature 22-26 ℃ in the ponds are suboptimal for breeding the channel catfish, nevertheless the productivity in ponds is 3 tons/ha, in cages 50-60 kg/m3, and in pools with thermo-regulation of water 100-150 kg/m3. In some trial water bodies, the natural breeding of channel catfishes were observed, proving the existence of independent （self-breeding） populations. This process however was significantly hampered by severe economical hardship occurred in the country during 1990＇s joined with the uncontrolled fishery. The current economical growth in the country also influences the aquaculture sector and many private fish farmers are interested in commercial breeding of channel catfish, scarce population of which still exists in the former experimental water bodies. The bio-technology of rearing the channel catfish, elaborated during the 1980s, is part of the aquaculture curricula in the universities.展开更多
文摘Genetic transformation is a powerful biotechnology for introducing novel genes into economically important plants from distantly-related plants or even unrelated species such as microbes and animals.This feat is impossible to be achieved by conventional breeding techniques.Development of transgenic plants has been a controversial subject since 1971 when the first genetically modified organism（GMO）was developed（James and Krattiger1996）.
文摘The channel catfish Ictalurus punctatus was first introduced from the United States to the Krasnodar region of Russia 1972-1979, and it was introduced into Georgia during 1976-1978. Ecological and economic studies of channel catfish were initiated along with the acclimatization and naturalization of this new species. Channel catfish were initially reproduced and reared in the Japan aquaculture fish farm ponds. Offspring from these ponds were used to stock other ponds, industrial fish farms and natural water bodies （lakes） where natural populations were formed. The climatic conditions of Georgia are close to the natural habitat of channel catfish. The number of days with water temperature higher than 20 ℃ is about 120-140, and the accumulated heat reaches up to 2,400-2,792℃. The purpose of targeted acclimatization was for the development of aquaculture-commercial production and recreational fisheries. During the process the method of staged radial acclimatization was applied, which initially included breeding and growing of fishes in aquaculture farms. Offspring produced in hatchery were then introduced into new fish farms and water bodies to develop populations. The water temperature 22-26 ℃ in the ponds are suboptimal for breeding the channel catfish, nevertheless the productivity in ponds is 3 tons/ha, in cages 50-60 kg/m3, and in pools with thermo-regulation of water 100-150 kg/m3. In some trial water bodies, the natural breeding of channel catfishes were observed, proving the existence of independent （self-breeding） populations. This process however was significantly hampered by severe economical hardship occurred in the country during 1990＇s joined with the uncontrolled fishery. The current economical growth in the country also influences the aquaculture sector and many private fish farmers are interested in commercial breeding of channel catfish, scarce population of which still exists in the former experimental water bodies. The bio-technology of rearing the channel catfish, elaborated during the 1980s, is part of the aquaculture curricula in the universities.
