Uso da técnica de micronúcleos para análise de instabilidade cromossômica induzida por radiação beta em células de Allium CEPA

Abstract

The assessment of the cytogenetic effects of ionizing radiation on plants can play a fundamental role in promptly responding to and/or mitigating the recurring impacts of the release of radioactive materials into the environment and, consequently, reducing the risk to the population. The objective of this work was to analyze the potential of acute exposure to beta particles to induce chromosomal instability in onion (Allium cepa) root cells after 3 cell cycles of cessation of exposure. The choice of Allium cepa was due to it being a biota frequently used as a standard model in cytogenetic studies related to environmental pollutants, however, little explored in the context of the effects of ionizing radiation. One of the most used techniques to evaluate cytogenetic damage is the micronucleus assay, which was applied in this work. For this, onion seeds were previously germinated and exposed, in groups, to a source of 90Sr/90Y at absorbed doses of 0.36, 0.72 and 1.44 Gy. Each group followed a non-irradiated control group. The levels of cytogenetic damage to Allium cepa cells were analyzed via optical microscopy, considering the frequency of cells with micronuclei (FMN) and the mitotic index (MI) over three cell cycles. With these data in hand, statistical tests were carried out to verify statistical significance. The main results clearly showed the influence of the mitotic index in the detection of cells with single and multiple MN. The dose of 0.36 Gy induced a gradual decrease in IM throughout the three cell cycles investigated. For the dose of 1.44 Gy, there was no such reduction in the first post-irradiation cycle, but rather in the following cycles, with reductions of 3/4 and 2/3, respectively, compared to the IM after the first cycle. The data suggest that Allium cepa roots can adapt to higher doses, despite showing chromosomal instability at all doses studied.