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|Title:||Experimental studies on the cell cycle of cultured sycamore cells.|
|Authors:||Gould, Alan R.|
|Presented at:||University of Leicester|
|Abstract:||Investigations concerning the cell cycle of Acer pseudoplatanus L. (sycamore) in suspension culture have generated the following general conclusions: 1) The sycamore suspensions used in the study exhibit extensive aneuploid development away from the diploid chromosome number of 2n = 4x = 52. 2) The evolution of new aneuploid chromosome complements may well still be in progress. 3) Stationary phase DNA distributions can be used to estimate chromosome numbers. 4) In common with animal and other plant cell types, the G1 phase is the most variable part of the DNA replication- partition cycle. 5) The S-G2-M sequence is of relatively constant duration in exponentially growing populations. 6) The S-G2-M sequence duration is lengthened in slowly dividing chemostat cultures, under glucose or nitrate limitation. 7) If cells are arrested in stationary phase by sucrose or phosphate starvation they arrest in the G1 and G2 phases in the approximate ratio of 4 : 1. If cells are arrested by nitrate starvation they accumulate almost exclusively in G1. 8) The G1 accumulation of nitrate starved cells is probably the mechanism by which synchrony is achieved when late stationary phase cells are inoculated into fresh medium. 9) Calculation of Scherbaum synchrony indices from cell count data, shows that the Acer system is well synchronised in terms of cell division. 10) The persistence of synchronous division and the absence of progressive synchrony decay, suggests that some form of intercellular entrainment occurs in the suspension cultures. 11) In synchronously dividing populations, DNA synthesis is also synchronous, and in terms of an S phase synchrony index, DNA replication becomes more highly synchronised as cell density rises and interphase duration is reduced. 12) Histones appear to be synthesised continuously during interphase in synchronised Acer suspensions but the rate of histone synthesis appears to be highest during S-phase.|
|Rights:||Copyright © the author. All rights reserved.|
|Appears in Collections:||Theses, Dept. of Biology|
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