title: Non-cell autonomous regulation of life cycle transitions in the model brown alga Ectocarpus.
abstract: The model brown alga Ectocarpus has a haploid-diploid life cycle, involving alternation between two independent multicellular generations, the gametophyte and the sporophyte. Recent work has shown that alternation of generations is not determined by ploidy but is rather under genetic control, involving at least one master regulatory locus, OUROBOROS (ORO). Using cell biology approaches combined with measurements of generation-specific transcript abundance we provide evidence that alternation of generations can also be regulated by non-cell autonomous mechanisms. The Ectocarpus sporophyte produces a diffusible factor that causes major developmental reprogramming in gametophyte cells. Cells become resistant to reprogramming when the cell wall is synthetized, suggesting that the cell wall may play a role in locking an individual into the developmental program that has been engaged. A functional ORO gene is necessary for the induction of the developmental switch. Our results highlight the role of the cell wall in maintaining the differentiated generation stage once the appropriate developmental program has been engaged and also indicate that ORO is a key member of the developmental pathway triggered by the sporophyte factor. Alternation between gametophyte and sporophyte generations in Ectocarpus is surprisingly labile, perhaps reflecting an adaptation to the variable seashore environment inhabited by this alga.
authors.affiliation: UMR 7139, Laboratoire International Associé Dispersal and Adaptation in Marine Species, Station Biologique de Roscoff, CNRS, Place Georges Teissier, BP74, 29682, Roscoff Cedex, France.|The Marine Plants and Biomolecules Laboratory, UMR 7139, UPMC Université Paris 06, Station Biologique de Roscoff, BP74, 29682, Roscoff Cedex, France.
authors.forename: Alok
authors.initials: A
authors.lastname: Arun
authors.affiliation: UMR 7139, Laboratoire International Associé Dispersal and Adaptation in Marine Species, Station Biologique de Roscoff, CNRS, Place Georges Teissier, BP74, 29682, Roscoff Cedex, France.|The Marine Plants and Biomolecules Laboratory, UMR 7139, UPMC Université Paris 06, Station Biologique de Roscoff, BP74, 29682, Roscoff Cedex, France.|Department of Biology, University of Utah, Salt Lake City, Utah, USA.
authors.forename: Nick T
authors.initials: NT
authors.lastname: Peters
authors.affiliation: UMR 7139, Laboratoire International Associé Dispersal and Adaptation in Marine Species, Station Biologique de Roscoff, CNRS, Place Georges Teissier, BP74, 29682, Roscoff Cedex, France.
authors.forename: Delphine
authors.initials: D
authors.lastname: Scornet
authors.affiliation: UMR 7139, Laboratoire International Associé Dispersal and Adaptation in Marine Species, Station Biologique de Roscoff, CNRS, Place Georges Teissier, BP74, 29682, Roscoff Cedex, France.|The Marine Plants and Biomolecules Laboratory, UMR 7139, UPMC Université Paris 06, Station Biologique de Roscoff, BP74, 29682, Roscoff Cedex, France.|Bezhin Rosko, 29250, Santec, France.
authors.forename: Akira F
authors.initials: AF
authors.lastname: Peters
authors.affiliation: UMR 7139, Laboratoire International Associé Dispersal and Adaptation in Marine Species, Station Biologique de Roscoff, CNRS, Place Georges Teissier, BP74, 29682, Roscoff Cedex, France.|The Marine Plants and Biomolecules Laboratory, UMR 7139, UPMC Université Paris 06, Station Biologique de Roscoff, BP74, 29682, Roscoff Cedex, France.
authors.forename: J
authors.initials: J
authors.lastname: Mark Cock
authors.affiliation: UMR 7139, Laboratoire International Associé Dispersal and Adaptation in Marine Species, Station Biologique de Roscoff, CNRS, Place Georges Teissier, BP74, 29682, Roscoff Cedex, France.|The Marine Plants and Biomolecules Laboratory, UMR 7139, UPMC Université Paris 06, Station Biologique de Roscoff, BP74, 29682, Roscoff Cedex, France.
authors.forename: Susana M
authors.initials: SM
authors.lastname: Coelho
mesh_terms: D001557:Benzenesulfonates / Q000378:metabolism; D017077:Culture Media, Conditioned / Q000494:pharmacology; D056426:Genetic Loci / Q000235:genetics; D055993:Germ Cells, Plant / Q000166:cytology / Q000187:drug effects / Q000254:growth & development; D008954:Models, Biological; D000459:Phaeophyceae / Q000166:cytology* / Q000187:drug effects / Q000235:genetics / Q000254:growth & development*; D011523:Protoplasts / Q000187:drug effects / Q000378:metabolism; D012038:Regeneration / Q000187:drug effects
chemical_list: D001557:Benzenesulfonates; D017077:Culture Media, Conditioned; C007061:C.I. Fluorescent Brightening Agent 28