Onset Time of Signal for Mitosis Estimated from Mitotic Delays in UV-Irradiated Plasmodia of Physarum polycephalum

[摘要] References(14)Cited-By(7)Mitotic delay by UV-irradiation was examined in G2 or M phase in naturally synchronous plasmodia of Physarum polycephalum. The mitotic delay curve indicated a linear decrease against the time of irradiation in G2. Extrapolation ofthe delay line in G2 to zero delay gave an intersection point which probably coresponded to the transition point from G2to 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 wasfrom late G2 cells.

[学科分类] 分子生物学，细胞生物学和基因