Development of a micronucleus assay in the root tips of Allium cepa seedlings as a detector of chemical clastogens

概要

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Micronuclear frequencies in the root-tip cells of A. cepa (onion) seedlings were scored at various times from 0 to 120 hr after X-irradiation. The resultant time course curve showed a clear peak at 24 hr after irradiation, irrespective of the dose applied. Similarly, after continual treatment of onions from the dormant to seedling stages (germinating seeds) with methylmethanesulfonate, the frequency of micronuclei reached a peak at 24 hr or a plateau at 48 to 72 hr and then decreased with time. A mitotic cycle duration of about 21 hr was deduced for the meristems from available time course data. CoCl_2 was registered as a metal compound with higher genotoxic potency than As_2O_3 in germinating onion seeds as assayed for micronuclei at 24 hr after treatment. For all of the agents used, a clear dosage effect on the frequency of micronuclei was seen at the 24-hr sampling time when mitotic indexes of the meristems were at normal or subnormal levels. These results support the conclusion that the root-tip micronucleus assay in onion seedlings can be used as a simple detector of chemical clastogens.
日本環境変異原学会の論文
2000-02-28