Avalia??o da influência do tempo de exposi??o de Tradescantia pallida var. purpurea para biomonitoramento da genotoxicidade do ar atmosférico

摘要

Tradescantia pallida (Rose) D.R. Hunt var. purpurea Boom is used to assess the genotoxicity of atmospheric air due to the formation of micronuclei (MCN) in meiotic tetrads after acute exposure. We aimed to investigate whether there is a quantitative relationship between MCN formation and the amount of hours of acute air-exposure of branches with flower buds, both in a natural environment and under controlled conditions. In bioassay I, branches with flower buds were exposed to air for 8, 24 or 32 h in S?o Leopoldo city, Southern Brazil, and in a sealed environment, from April 2012 to January 2013 on a quarterly basis. In bioassay II, the exposure of branches with flower buds for 8 hours to the air in S?o Leopoldo and indoor took place from May 2013 to February 2014, on the same basis. The MCN formation showed no relationship with the time of exposure, as no significant difference could be verified between the MCN frequencies in flower buds exposed for 8, 24 or 32 h, neither in S?o Leopoldo (means of 4.8, 4.8 and 4.2) nor in the sealed environment (means of 1.6, 1.5 and 1.3). Flower buds exposed for 8 h showed significantly higher MCN frequencies (1.6 to 7.8) than the ones from the negative control (1.2 to 2.0) in six out of eight exposures, thus evidencing the genotoxicity of the air in S?o Leopoldo. We highlight the importance of the MCN bioassay with T. pallida var. purpurea in environmental diagnoses.