[Response of HeLa cells to mitomycine C. II. Morphometry of the cells]

HeLa-M cells were analyzed after the 2h incubation in the medium with mitomycin C (10 μg/ml). It has been shown that a part of the cells contacted with the cytostatic agent passes mitosis normally, but the daughter cells no longer divide. During the observation period (2 days), the area of the cells increased linearly reaching twice the size of intact cells. Thereby spreading of the cells contacted with mitomycine decreased, and their polarisation was not changed. Along with the increasing cell size, the nucleus size is also increased indicated de novo protein synthesis. Analysis of nucleoli revealed a small decrease of their area during the first hours after the contact with mitomycine followed by an increase of the area. Finally, the nucleolus area exceeded that of control cells, which can only happen if rRNA was synthesized. On the other hand, DNA cross-linking by mitomycine should inhibit transcription because the mechanism of transcription is assumed to involve local melting of DNA within its minor groove. This contradiction can be overcome by assuming that transcription occurs in a DNA major groove without separation of the chains.