Efeito de 5-Aminouracil na divisão mitótica de células de <em>Allium cepa</em>

Abstract

Cytological preparations of Allium cepa meristematic cells were examined under a light microscope to evaluate the effect of prolonged exposure (at least two-cell cycle) to 5-aminouracil (5-AU) on mitotic cell division in the roots. The results are a cytological demonstration that a lower concentration of 5-AU than usually employed for synchronizing proliferating cells in A. cepa root meristems induces chromosomal abnormalities and formation of micronucleus but does not fully block the cell flow into mitosis, and that micronucleated cells can proceed in mitosis and contribute to the enhancement of root length values reported by other authors. A. cepa root tip cells seems to support a certain damage level in DNA (around 10% of micronucleated cells in mitosis) without having any negative effect on cellular proliferation and growth of the roots. This genetic flexibility of vegetable genomes may permit an attenuation of the adaptative metabolic-response to sustained adverse environmental conditions.