| Budget Amount *help |
¥1,600,000 (Direct Cost: ¥1,600,000)
Fiscal Year 1987: ¥300,000 (Direct Cost: ¥300,000)
Fiscal Year 1986: ¥1,300,000 (Direct Cost: ¥1,300,000)
|
|---|
| Research Abstract |
One event of chromosome conformation in the cell cycle is chromosome condensation during the division phase, resulting in the most condensed structure at metaphase. Under natural conditions, it is called taht the structure of metaphase chromosomes are constant in respective species, with slight defferences between mitotic and meiotic cells. However, it was supposed that the structure of metaphase chromosomes, teh degree of the condensation during prophase, would be variable under artificial conditions. This study was carried out to try this supposition and to obtaine cells with contorolled lengths of metaphase chromosomes.
When Trillium plants with anthers containing microsporocytes during the premeiotic interphase were exposed to high temparature (30゜C) for 4 days, the meiotic cells showed various types of division patterns and various degrees of chromosome condensation at metaphase. The most condensed chromosomes were obtained from plants treated at the early S phase by the heat, the length being shortened to 1/3 of the control.
Chemical treatments with several inhibitors of cell division were also effective on the control of chromosome condensation. 5-fluorouracil at a concentration of 4 mM showed a remarbable effect on the condensation.
The relevance of the completion of DNA synthesis to the progress of chromosome condensation was also examined using lily microsporocytes at zygotene stage. Deoxyadenosine, which arrests meiotic development at the early zygotene stage, markedly suppressed DNA synthesis to 35% of control at 2 mM. Only the completion of the synthesis of chromosomal DNA after the removal of the inhibitor allowed the cells to develop into the subsequent process of meiosis.
|
