Inactivation of DNA replication origins by the cell cycle regulator, trigonelline, in root meristems of Lactuca sativa |
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Authors: | S Mazzuca M B Bitonti A M Innocenti D Francis |
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Institution: | (1) Department of Ecology, University of Calabria, 87030 Arcavacata di Rende, Italy, IT;(2) School of Biosciences, Cardiff University, PO Box 915, Cardiff CF1 3TL, UK, GB |
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Abstract: | The effects of trigonelline (TRG) on the cell cycle in root meristems of Lactuca sativa L. were examined in the knowledge that TRG is a cell cycle regulator that causes cell arrest in G2, and prevents ligation
of replicons in S-phase. The hypothesis was tested that continuous exposure to TRG would perturb DNA replication which, in
turn, would lengthen the cell cycle and impair root elongation. Using DNA fibre autoradiography, mean replicon size was 31
and 13 μm in the TRG (3 mM) and control treatments, respectively. Trigonelline also resulted in a lengthening of both S-phase
and the cell cycle and a decrease in primary root elongation. Hence, replicon inactivation was responsible for the protracted
S-phase. Trigonelline treatment also resulted in a 1.6-fold increase in fork rate (13.8 μm h−1) compared with the control (8.4 m h−1). The faster fork rate in the larger replicons is in accord with the highly significant positive relationship already established
between fork rate and replicon size for various unrelated higher plants.
Received: 11 October 1999 / Accepted: 23 December 1999 |
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Keywords: | : Cell cycle – DNA replication – Lactuca (cell cycle) – Replicon – Root meristem – Trigonelline |
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