In this study, the micronuclei test (MNT) was applied in exfoliated cells of buccal mucosa, in order to evaluate the genotoxic risk associated with occupational exposure of mechanics, storage battery renovation workers, and car painters. For each individual, 3000 exfoliated buccal cells were analyzed. There was a significantly higher frequency of micronucleated cells (MNC) in the exposed workers than in controls. Smoking and drinking habits, age, and working time did not represent significant factors in terms of increasing the production of micronuclei (MN), when the control and the exposed groups were compared. These results allowed to conclude that the studied individuals belong to a risk group and should periodically undergo biological monitoring and proper care.

Objetivando uma melhor análise citogenética das formigas cortadeiras Atta sexdens piriventris e Acromyrmex heyeri, algumas modificações foram feitas no sentido de otimizar a metodologia de Imai et al. (Jpn. J. Genet. 63: 159-185, 1988), tendo-se conseguido a diminuição do tempo de preparo do material e melhor qualidade da preparação. O gânglio cerebral de pré-pupa foi dissecado em solução de colchicina hipotônica 0,0025% e colocado sobre lâmina de vidro (nova e previamente limpa para ser corada com Giemsa) com colchicina hipotônica. A lâmina foi colocada sobre placa de gelo (4 ± 1oC) por 20 min. O material foi fixado diretamente na lâmina (com fixador I gelado), macerado com agulha histológica e fixado novamente com fixador I, seguido dos fixadores II e III, todos gelados. A lâmina foi rapidamente flambada após a última fixação e foi deixada secar à temperatura ambiente por 2 h. As metáfases resultantes apresentaram, com maior freqüência, cromossomos menos contraídos, com cromátides irmãs separadas e bem definidas, quando o material foi processado como descrito acima e corado com solução de Giemsa 3% em tampão fosfato pH 6,8, por 15 min.

Some modifications were made to the methodology of Imai et al. (Jpn. J. Genet. 63: 159-185, 1988) for cytogenetic analysis of the leaf-cutting ants Atta sexdens piriventris and Acromyrmex heyeri (Hymenoptera, Formicidae), shortening preparation time and improving chromosomal preparations. The brain ganglia of prepupae were dissected in a 0.0025% hypotonic solution of colchicine, placed on a glass slide on a cold plate (4 ± 1oC) for 20 min. The material was fixed directly on the cold slide (with cold fixative I), macerated with a histological needle and fixed again with fixative I, followed by fixatives II and III, all of them cold. The slide was flame-dried right after the use of fixative III, and it was allowed to air-dry at room temperature for 2 h. The resulting metaphases presented less contracted chromosomes, with separated and well defined sister chromatids at a high frequency, when the material was processed in the manner described and stained with 3% Giemsa in phosphate buffer (pH 6.8) for 15 min.