title: Low-molecular-weight factors from colonial hydroids affect pattern formation.
abstract: Two morphogenetic factors have been isolated from tissue of colonial hydroids. Both exert strong effects on pattern formation during metamorphosis, regeneration and colony development. Polyp-inhibiting factor (PIF) is a bivalent inhibitor which strongly affects head and bud formation but acts weakly on stolon branching. Proportion-altering factor (PAF) is a distalizing factor. It counteracts the formation of stolon and promotes the formation of head structures during metamorphosis and regeneration. PIF and PAF antagonistically influence the spatial arrangement of polyps within a colony. They are capable of dislocating structures and thus appear to interfere with or are even part of the pattern-controlling mechanism. Both factors are of low molecular size (about 500 daltons), hydrophilic and probably not peptides.
authors.affiliation: Zoologisches Institut, Universität, Im Neuenheimer Feld 230, D-6900, Heidelberg, Germany.
authors.forename: Günter
authors.initials: G
authors.lastname: Plickert
keywords: Colonial hydroids; Eirene viridula; Hydractinia echinata; Metamorphosis; Pattern formation