MICRONUCLEI IN IRRADIATED MERISTEMS
The percentages of cells with micronuclei counted at intervals after acute x irradiation of the root meristems of Zea mays show two peaks. These two peaks occur clearly only after heavy doses (900 and 1800 rads) and only when restricted regions of the root tip are considered, not when squashes of whole tips are used. The first peak, which occurs at four days after irradiation at 1800 rads, is probably due to those cells that were in G/sub 2/ at the time of irradiation coming into their first post-irradiation mitosis. The second peak, which occurs at eight days after 1800 rads, is probably due to those cells that were in Gi at irradiation being delayed more severely than the other cells in coming into mitosis. The dip between the two peaks can be accounted for on the assumption that the cells in G/sub 2/ at irradiation undergo second and subsequent mitoses before the G/sub 1/ cells undergo their first division thus lowering the percentage of cells with micronuclei. The temporal positions and the relative heights of the maxima are discussed in relation to the dose and the lengths of the mitottc cycle in the various regions of the meristem. The quiescent center of the meristem is less sensitive to x rays than the other regions at all dose levels and in it mitosis is stimulated by irradiation. (auth)
- Research Organization:
- Oxford Univ.
- Sponsoring Organization:
- USDOE
- NSA Number:
- NSA-18-005080
- OSTI ID:
- 4123040
- Journal Information:
- Radiation Botany, Journal Name: Radiation Botany Vol. Vol: 3
- Country of Publication:
- Country unknown/Code not available
- Language:
- English
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