The effects of griseofulvin on mitosis in Aspergillus nidulans

Abstract

The effects of the antifungal agent, griseofulvin, on mitosis in a diploid strain of Aspergillus nidulans has been studied. Helly-fixed preparations stained with acid fuchsin normally reveal densely staining, spherical nucleoli, lateral granules accompanying the nucleoli, and spindles in various stages of development. The development of this granule results in the formation of a small cigar-shaped spindle which increases in size in later stages of division and then becomes stretched out into a thin, long fiber at the termination of division.Cultures treated with griseofulvin reveal damaged and distorted spindles within 30 s to 1 min after treatment. After 1 min or more of drug treatment, no normal spindles are seen but granules forming the polar regions of the spindle persist.The division of the chromatin during mitosis is also distorted by griseofulvin treatment. Cultures treated with this drug reveal abnormal chromatin configurations after 15–20 min. Individual chromosomes such as those seen at metaphase-like stages become distorted into a dense mass of chromatin. The further stages of division reveal abnormally stretched out lengths of chromatin which are, however, capable of division by a break in the constricted thread near the center.Spindles appear to recover from the griseofulvin treatment when treated cultures are transferred to fresh medium not containing griseofulvin at 35 °C for 90 min.