[Antimitotic activity of methylbenzimidazol-2-yl-carbamate (MBC). I. Light, electron microscopic and physiological studies of germinating conidia of Aspergillus nidulans].

In the presence of methylbenzimidazol-2-yl carbamate (MBC) swelling of conidia of Aspergillus nidulans was not influenced. The total DNA content per nucleus doubled only once, indicating that the first cell cycle was arrested in the G2-period. Later RNA as well as protein synthesis were inhibited. Nuclear migration into the germ tube and tip growth were delayed. MBC-treatment induced nuclear enlargement and inhibited the first nuclear division in the germinating conidia. A characteristic nuclear invagination developed within which in most cases the enlarged "single NAO" and more less the formed "double NAO" are localized. On the basis of ultrathin sections a model is suggested in which the typical position of "double NAO" in nuclear invagination is demonstrated. The possible relationship between nuclear invagination and NAO-formation, as well as its eventual importance are discussed.