Speaker
Description
Ectocarpus is a filamentous brown alga whose cells are surrounded by a cell wall [1]. Using a visco-plastic model, we previously demonstrated that the polarised apical growth of its prostrate, uniserial filaments is regulated by changes in cell wall thickness, independent of alterations to the material's mechanical properties [2]. Apical growth is accompanied by transverse cell divisions, generating a new growing apical cell and an ‘inert’ subapical cell. More recently, time-lapse observations at various timescales have demonstrated the following: 1) growth occurs according to two patterns of cell elongation rate oscillation; 2) cell divisions are synchronised with these oscillations; and 3) the filament’s growth trajectory proceeds in undulations, the changes in direction of which are synchronised with the oscillations. We are now investigating the functional relationships between these three biological processes: growth oscillations, cell divisions, and changes in growth direction. To do so, we are using a bank of Ectocarpus mutants that exhibit alterations in apical growth (e.g. the etoile mutant [3,4]), as well as pharmacological treatments to dissociate these three parameters. The results will feed a multi-component cellular growth model and identify the molecular players involved in controlling these growth processes in brown algae. As algae diverged from other multicellular eukaryotes over 1.2 billion years ago, the results of this study will enable us to compare the various tip growth strategies that have evolved within the tree of life.
Bibliography
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author = {Charrier, B. and Coelho, S. M. and Le Bail, A. and Tonon, T. and Michel, G. and Potin, P. and Peters, A. F. and Cock, J. M.},
title = {Development and Physiology of the Brown Alga Ectocarpus siliculosus: Two Centuries of Research},
journal = {New Phytologist},
volume = {177},
number = {2},
pages = {319--332},
year = {2008}
}
@article{rabille2019tipgrowth,
author = {Rabillé, H. and Billoud, B. and Le Bail, A. and Charrier, B.},
title = {The Brown Algal Mode of Tip Growth: Keeping Stress under Control},
journal = {PLoS Biology},
volume = {17},
pages = {e2005258},
year = {2019}
}
@article{lebail2011etoile,
author = {Le Bail, A. and Billoud, B. and Maisonneuve, C. and Peters, A. F. and Cock, J. M. and Charrier, B.},
title = {ETOILE Regulates Developmental Patterning in the Filamentous Brown Alga Ectocarpus siliculosus},
journal = {The Plant Cell},
volume = {23},
pages = {1666--1678},
year = {2011}
}
@article{nehr2011spacetime,
author = {Nehr, Z. and Le Bail, A. and Billoud, B. and Charrier, B.},
title = {Space-Time Decoupling in the Branching Process in the Mutant {\'E}toile of the Filamentous Brown Alga Ectocarpus siliculosus},
journal = {Plant Signaling \& Behavior},
volume = {6},
pages = {1889--1892},
year = {2011}
}
