title: Parameters of self-organization in Hydra aggregates.
abstract: Self-organization has been demonstrated in a variety of systems ranging from chemical-molecular to ecosystem levels, and evidence is accumulating that it is also fundamental for animal development. Yet, self-organization can be approached experimentally in only a few animal systems. Cells isolated from the simple metazoan Hydra can aggregate and form a complete animal by self-organization. By using this experimental system, we found that clusters of 5-15 epithelial cells are necessary and sufficient to form de novo head-organizing centers in an aggregate. Such organizers presumably arise by a community effect from a small number of cells that express the conserved HyBra1 and HyWnt genes. These local sources then act to pattern and instruct the surrounding cells as well as generate a field of lateral inhibition that ranges up to 1,000 microm. We propose that conserved patterning systems in higher animals originate from extremely robust and flexible molecular self-organizing systems that were selected for during early metazoan evolution.
authors.affiliation: Department of Molecular Cell Biology, Darmstadt University of Technology, Schnittspahnstr. 10, 64287 Darmstadt, Germany. technau@bio.tu-darmstadt.de
authors.forename: U
authors.initials: U
authors.lastname: Technau
authors.forename: C
authors.initials: C
authors.lastname: Cramer von Laue
authors.forename: F
authors.initials: F
authors.lastname: Rentzsch
authors.forename: S
authors.initials: S
authors.lastname: Luft
authors.forename: B
authors.initials: B
authors.lastname: Hobmayer
authors.forename: H R
authors.initials: HR
authors.lastname: Bode
authors.forename: T W
authors.initials: TW
authors.lastname: Holstein
mesh_terms: D000818:Animals; D006829:Hydra / Q000254:growth & development*; D017403:In Situ Hybridization