| Budget Amount *help |
¥4,400,000 (Direct Cost: ¥4,400,000)
Fiscal Year 1990: ¥1,100,000 (Direct Cost: ¥1,100,000)
Fiscal Year 1989: ¥3,300,000 (Direct Cost: ¥3,300,000)
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| Research Abstract |
Experiments on chromosome manipulation have been tried in various fields of biotechnology. As far as fisheries, there were many trials to manipulate the genoms by means of artificial methods. In this study, we attempted to new strain that contained a genoms and useful characteristics in aquaculture.
First of all, we tried to decide the best condition that were able to evoke gene alternation in fertilized salmonid eggs. We concluded after the examinations that the best way to change the gene combination is heat shock. Rapid immersion into warm water at 28C for 15 min after 15 min of water activation was highly effective in salmonid species.
To recognize the ploidy changes under chromosome levels, the number of the nucleoli in each nucleus was counted under the light microscope after staining by silver nitrite. Cyteーflow metric method that was available to detect the DNA density in the nucleus was also useful.
After methodological confirmation, we compared the characteristics in various salmonid hybrids of diploids and triploids including not only the allotypes but also heterotypes. We made many hybrids among the rainbow trout, brout, yamame (Oncorhynchus masou), brook trout, Japanese char etc. Rate of egg developments, percent hatch, early mortality and growth rate were compared among the hybrids. There were no significant differences in the rate of egg development and the growth. However, survival rates of the hybrids between rainbow trout (female) and brown trout (male) as well as between yamame and brown trout were mote higher in the triploids than the diploids. Their shape were more fat than the parents and seemed to be a preferable from the commercial point of view.
Following the results obtained in this study, it may be concluded that ploidy manipulation is a effective tool for the breeding of commercially important fish species.
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