Journal of Experimental Botany, Vol 50, 1373-1379, Copyright © 1999 by Oxford University Press
A Peres, F Ayaydin, K Nikovics, C Gutierrez, G Horvath, D Dudits and A Feher
Optimization of culture and treatment conditions for reproducible
synchronization of the cell cycle in maize cells with hydroxyurea is
described. Flow cytometric measurements of relative DNA contents revealed
that, following the hydroxyurea block, around 55% of the cells were in the
G1 phase (2C), 30% in the S phase (2C<S>4C) and 15% in the G2
phase (4C) of the cell cycle. The highest frequencies of cells in the S
phase could be observed 2 h after removal of hydroxyurea (35-40%). The
cells reached increased G2 phase frequencies (60-70%) between 8-14 h, while
the maximum number of mitotic cells (12-14%) were found between 14-17 h.
Northern analysis of total RNA from the synchronized cells indicated an
increased level of transcripts from two histone (H3Zm, H4Zm) genes during
the S-phase. The changes in the mRNA levels of the maize cyclin variants
CycB1;zm;1, CycB1;zm;2 and CycA1;zm;1 support the classification of these
cyclins as mitotic cyclins with transcript accumulation during the G2/M
cell cycle phases. Using the maize retinoblastoma (ZmRb-1) cDNA as
hybridization probe, two transcripts were detected with different
hybridization intensity: the smaller, more abundant transcript was
recognized during the whole cell cycle with an increase after the release
of the cells from the hydroxyurea block, while the larger mRNA could only
be detected for 8 h afer removal of hydroxyurea. The ZmRb-1 gene might
respond to the increase of the frequency of cells in the S phase or to the
re-addition of conditioned medium to the cells after hydroxyurea
removal.Key words: Cell cycle, cell synchronization,
gene expression, Zea mays L.
ARTICLES
Partial synchronization of cell division in cultured maize (Zea mays L.) cells; differential cyclin, cdc2, histone, and retinoblastoma transcript accumulation during the cell cycle
Institute of Plant Biology, Biological Research Center, POB 521, H-6701 Szeged, Hungary; Centro de Biologia Molecular 'Severo Ochoa' (CSIC-UAM), Universidad Autonoma de Madrid, Cantoblanco, 28049 Madrid, Spain; Corresponding author e-mail: fehera@nucleus.szbk.u-szeged.hu
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