Ca2+ signals coordinate zygotic polarization and cell cycle progression in the brown algaFucus serratus
Author:
Bothwell John H. F.1, Kisielewska Jolanta2, Genner Martin J.1, McAinsh Martin R.3, Brownlee Colin1
Affiliation:
1. Marine Biological Association of the UK, The Laboratory, Citadel Hill,Plymouth PL1 2PB,UK. 2. University of Newcastle-upon-Tyne, Institute of Cell and Molecular Biosciences, Medical School, Framlington Place, Newcastle NE2 4HH, UK. 3. Department of Biological Sciences, Lancaster Environment Centre, Lancaster University, Lancaster LA1 4YQ, UK.
Abstract
Zygotes of the fucoid brown algae provide excellent models for addressing fundamental questions about zygotic symmetry breaking. Although the acquisition of polarity is tightly coordinated with the timing and orientation of the first asymmetric division-with zygotes having to pass through a G1/S-phase checkpoint before the polarization axis can be fixed-the mechanisms behind the interdependence of polarization and cell cycle progression remain unclear. In this study, we combine in vivo Ca2+ imaging, single cell monitoring of S-phase progression and multivariate analysis of high-throughput intracellular Ca2+ buffer loading to demonstrate that Ca2+ signals coordinate polarization and cell cycle progression in the Fucus serratus zygote. Consistent with earlier studies on this organism, and in contrast to animal models, we observe no fast Ca2+ wave following fertilization. Rather, we show distinct slow localized Ca2+ elevations associated with both fertilization and S-phase progression, and we show that both S-phase and zygotic polarization are dependent on pre-S-phase Ca2+ increases. Surprisingly, this Ca2+ requirement cannot be explained by co-dependence on a single G1/S-phase checkpoint, as S phase and zygotic polarization are differentially sensitive to pre-S-phase Ca2+ elevations and can be uncoupled. Furthermore, subsequent cell cycle progression through M phase is independent of localized actin polymerization and zygotic polarization. This absence of a morphogenesis checkpoint, together with the observed Ca2+-dependences of S phase and polarization, show that the regulation of zygotic division in the brown algae differs from that in other eukaryotic model systems, such as yeast and Drosophila.
Publisher
The Company of Biologists
Subject
Developmental Biology,Molecular Biology
Reference66 articles.
1. Anderegg, G. and Wenk, F. (1967). Pyridinderivate als Komplexbildner VIII. Die Herstellung je eines neuen vier-and sechszähnigen Liganden. Helv. Chim. Acta50,2330-2332. 2. Antoine, A. F., Faure, J. E., Cordeiro, S., Dumas, C., Rougier,M. and Feijo, J. A. (2000). A calcium influx is triggered and propagates in the zygote as a wavefront during in vitro fertilization of flowering plants. Proc. Natl. Acad. Sci. USA97,10643-10648. 3. Arslan, P., Di Virgilio, F., Beltrame, M., Tsien, R. Y. and Pozzan, T. (1985). Cytosolic Ca2+ homeostasis in Ehrlich and Yoshida carcinomas. A new, membrane-permeant chelator of heavy metals reveals that these ascites tumor cell lines have normal cytosolic free Ca2+. J. Biol. Chem.260,2719-2727. 4. Berger, F. and Brownlee, C. (1993). Ratio confocal imaging of free cytoplasmic calcium gradients in polarising and polarised Fucus zygotes. Zygote1, 9-15. 5. Bothwell, J. H., Brownlee, C., Hetherington, A. M., Ng, C. K.,Wheeler, G. L. and McAinsh, M. R. (2006). Biolistic delivery of Ca2+ dyes into plant and algal cells. Plant J.46,327-335.
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