Adult toxicity and dominant lethals induced by ozone at specific stages in spermatogenesis in Drosophila virilis

Ozone, a highly reactive three-atom allotrope of oxygen, is formed in high concentrations in various kinds of microenvironments, including electron microscopes, office copy machines, and X-ray devices. Mutagenicity and action modus operandi of ozone suggest its radiomimetic property. In order to test for ozone-induced dominant lethals in Drosophila virilis, we determined that four-hr and longer exposures to 30 +/- 2 ppm ozone were lethal on or before day 25 postexposure. Accordingly, we used a three-hr ozone exposure to investigate dominant lethals induced at specific spermatogenic stages. Ozone increased the percentage of dominant lethals in the stages of spermatogenesis which were investigated. Under the conditions of this experiment, the sperm-sperm bundle stage showed the greatest percentage of dominant lethals induced by ozone. Meiotic cells were the least sensitive to ozone mutagenicity. The induction of dominant lethals is discussed on the basis of chemical reactions from the molecular decomposition of water by radiations and/or ozone. Alternative explanations are presented due to the definition of induced dominant lethals and to associated modifications from ozone exposure.