Onset Time of Signal for Mitosis Estimated from Mitotic Delays in UV-Irradiated Plasmodia of Physarum polycephalum
- 1 January 1977
- journal article
- research article
- Published by Japan Society for Cell Biology in Cell Structure and Function
- Vol. 2 (2) , 101-109
- https://doi.org/10.1247/csf.2.101
Abstract
Mitotic delay by UV-irradiation was examined in G2 or M phase in naturally synchronous plasmodia of P. polycephalum. The mitotic delay curve indicated a linear decrease against the time of irradiation in G2. Extrapolation of the delay line in G2 to zero delay gave an intersection point which probably corresponded to the transition point from G2 to M, that is, the time of the signal for mitosis. The point was at 50 min prior to metaphase. The slope change of the delay curve suggests that UV-irradiation inhibits the production of a substance responsible for triggering mitosis rather than inactivate the function of a preexisting triggering substance. The delay was partially cancelled by adding the crude lysate of non-irradiated cells. This effect was strongest when the lysate was from late G2 cells.This publication has 0 references indexed in Scilit: