Mitotic Disturbances Induced By The Drug "Novalgin" In Allium Cepa Root Tips
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Growing root tips of Allium cepa are treated with seven concentrations of Novalgin ranging from 2.81 x 10 4 M to 1.5 x 10 4 M for 4, 8, 24,48 and 72 hours. The frequency of mitotic phases in the treated roots varies according to the concentration applied and period of treatment. Novalgin reduces the mitotic activity with the increase of concentration applied. Novalgin induces a wide range of mitotic abnormalities, their frequencies vary according to the concentration and period of treatment. These abnormalities include c-metaphase, chromosome stickiness, c-anaphase, tripolar groups, chromosome bridges, lagging of chromosomes at anaphase, micronuclei and multinuclei at the interphase stage. The most conspicuous type of abnormality is the ability of Novalgin to cause chromosome breakage which is noticed at different periods of treatment and at different concentrations applied, specially at low concentrations. The number of breaks varies from a single break to many at metaphase and acentric fragments at anaphase. A test for recovery is carried out by treating roots for 8 hours then fixing after 4, 24 and 48 hours. The roots start to restore normal activity after 48 hours recovery interval but a number of abnormalities are still seen.