Differential changes in copy numbers of rice mitochondrial plasmid-like DNAs and main mitochondrial genomic DNAs that depend on temperature
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- 作者：A. Kanazawa ; N. Tsutsumi and Atsushi Hirai
- 关键词：Key words Mitochondrial DNA ; Plasmid ; like DNA ; Temperature dependency ; Rice
- 刊名：Current Genetics
- 出版时间：July 1998
- 出版年：1998
- 期刊代码：63_0172-8083
- 类别：bio
- 卷：33
- 期：6
- 页码：437-444
- 数据来源：sp
摘要
The mitochondria of rice contain four kinds of circular plasmid-like DNAs, namely, B1, B2, B3 and B4, in addition to the main mitochondrial genomic DNAs. In order to examine the genetic stability of mitochondrial plasmid-like DNAs, changes in the amounts of plasmid-like DNAs and main mitochondrial genomic DNAs were analyzed in calli that had been cultured at various temperatures. The observed effect of temperature on the levels of plasmid-like DNAs was larger than that on the main mitochondrial genomic DNAs. A significant reduction in the copy number of plasmid-like DNAs was detected in calli cultured at 35 掳C, as compared to 20 掳C, 25 掳C and 30 掳C. The effect of temperature on DNA synthesis in isolated mitochondria was also analyzed. Synthesis of the main mitochondrial genomic DNAs occurred at all the temperatures examined, whereas synthesis of plasmid-like DNAs occurred only over a limited range of temperatures. The results of both in vivo and in vitro analyses suggest that plasmid-like DNAs are less stably maintained than the main mitochondrial genomic DNAs, which is consistent with the notion that the transmission of mitochondrial plasmid-like DNAs from one generation to the next may be unstable under unusual conditions.