Interdependence of the cell cycles of mammalian sister cells in monolayer cultures detected through their desynchronization by UV microirradiation

The duration and variability of cell cycles in epithelial and fibroblast-like mammalian sister cells with different types of intercellular contacts were estimated using time-lapse cinemicrographic technique. To study a possible interrelation between cell cycles of the sister cells, one cell in each pair of sister cells was inactivated by selective UV microbeam irradiation at the beginning of its cell cycle. It is shown that this action may delay the cycle of the intact cell as well. Such an interrelation of sister cells was found only at the G1 phase of the cell cycle and only in epithelial cells.