The effects of the fungicide captafol on mitosis of Aspergillus nidulans through light and electron microscopic investigations

In the present work the genetic activity of the fungicide captafol was studied in a heterozygous diploid strain of Aspergillus (Emericella) nidulans. In vitro fungitoxicity tests of captafol on mycelia growth showed a great increase of the color segregants. Analysis of white and yellow mitotic recombinants suggests that low captafol concentrations (0.075 µg/ml) increase the mitotic crossing-over frequency while non-disjunction was also occurred at high concentrations of 0.15 µg/ml. Light and electron microscopic observations of A. nidulans cells showed that captafol induces a number of cytological abnormalities in hyphae as well as in cell structures. A destruction of cytoplasmatic membrane, nucleus membrane and other membranes was also observed. At concentrations of the fungicide highly inhibitory to growth (more than 50%), an abnormal nuclear division was observed which did not follow the typical mitotic function usually observed in Ascomycetes. On the contrary, the formation of an unequal lobe was present, which leads in an unequal distribution of chromosomal material in the sub-nuclei.