Kinetic aspects of synchrony in suspension cultures of Acer pseudoplatanus L.

Synchronous divisions have been induced in cell suspension cultures of sycamore (Acer pseudoplatanus L.) initiated at low density from stationary phase, nitrate-starved cells. The pattern of division and DNA replication synchrony is unusual in that it does not show progressive decay but rather a sharp transition to asynchrony. Feulgen densitometry data indicate that in terms of an S-phase synchrony index, DNA replication becomes more highly synchronized as cell density rises and interphase duration is reduced. In comparison with asynchronous cultures the duration of mitosis appears to be reduced during synchronous growth. The persistence of division and S-phase synchrony and the apparent shortening of interphase and mitosis in these sycamore cultures suggests the operation of intercellular entrainment. The departure from synchrony during the interphase which precedes initiation of asynchronous division remains unexplained.