title: Dynamic BMP signaling polarized by Toll patterns the dorsoventral axis in a hemimetabolous insect.
abstract: Toll-dependent patterning of the dorsoventral axis in Drosophila represents one of the best understood gene regulatory networks. However, its evolutionary origin has remained elusive. Outside the insects Toll is not known for a patterning function, but rather for a role in pathogen defense. Here, we show that in the milkweed bug Oncopeltus fasciatus, whose lineage split from Drosophila's more than 350 million years ago, Toll is only required to polarize a dynamic BMP signaling network. A theoretical model reveals that this network has self-regulatory properties and that shallow Toll signaling gradients are sufficient to initiate axis formation. Such gradients can account for the experimentally observed twinning of insect embryos upon egg fragmentation and might have evolved from a state of uniform Toll activity associated with protecting insect eggs against pathogens.
authors.affiliation: Institute for Developmental Biology, University of Cologne, Köln, Germany.
authors.forename: Lena
authors.initials: L
authors.lastname: Sachs
authors.affiliation: Institute for Developmental Biology, University of Cologne, Köln, Germany.
authors.forename: Yen-Ta
authors.initials: YT
authors.lastname: Chen
authors.affiliation: Institute for Developmental Biology, University of Cologne, Köln, Germany.
authors.forename: Axel
authors.initials: A
authors.lastname: Drechsler
authors.affiliation: Institute for Developmental Biology, University of Cologne, Köln, Germany.
authors.forename: Jeremy A
authors.initials: JA
authors.lastname: Lynch
authors.affiliation: Institute for Developmental Biology, University of Cologne, Köln, Germany.
authors.forename: Kristen A
authors.initials: KA
authors.lastname: Panfilio
authors.affiliation: Institute for Theoretical Physics, University of Cologne, Cologne, Germany.
authors.forename: Michael
authors.initials: M
authors.lastname: Lässig
authors.affiliation: Institute for Theoretical Physics, University of Cologne, Cologne, Germany.
authors.forename: Johannes
authors.initials: J
authors.lastname: Berg
authors.affiliation: Institute for Developmental Biology, University of Cologne, Köln, Germany.
authors.forename: Siegfried
authors.initials: S
authors.lastname: Roth
mesh_terms: D000818:Animals; D005075:Biological Evolution; D019521:Body Patterning / Q000235:genetics*; D029721:Drosophila Proteins / Q000235:genetics / Q000378:metabolism; D004331:Drosophila melanogaster / Q000145:classification / Q000166:cytology / Q000196:embryology / Q000235:genetics; D004625:Embryo, Nonmammalian; D018507:Gene Expression Regulation, Developmental; D020062:Heteroptera / Q000145:classification / Q000166:cytology / Q000196:embryology / Q000235:genetics*; D019476:Insect Proteins / Q000235:genetics* / Q000378:metabolism; D008954:Models, Biological; D010802:Phylogeny; D015398:Signal Transduction / Q000235:genetics*; D051193:Toll-Like Receptors / Q000235:genetics* / Q000378:metabolism; D051879:Twist-Related Protein 1 / Q000235:genetics / Q000378:metabolism; D015053:Zygote / Q000166:cytology / Q000254:growth & development / Q000378:metabolism
chemical_list: D029721:Drosophila Proteins; D019476:Insect Proteins; D051193:Toll-Like Receptors; C497753:Twi protein, Drosophila; D051879:Twist-Related Protein 1; C064196:dpp protein, Drosophila; C091428:sog protein, Drosophila
keywords: Nasonia; Oncopeltus; Tribolium; axis formation; developmental biology; evolutionary biology; gene regulatory networks; genomics; oncopeltus fasciatus; pattern formation; stem cells