title: Evolutionary plasticity of collier function in head development of diverse arthropods.
abstract: The insect intercalary segment represents a small and appendage-less head segment that is homologous to the second antennal segment of Crustacea and the pedipalpal segment in Chelicerata, which are generally referred to as "tritocerebral segment." In Drosophila, the gene collier (col) has an important role for the formation of the intercalary segment. Here we show that in the beetle Tribolium castaneum col is required for the activation of the segment polarity genes hedgehog (hh), engrailed (en) and wingless (wg) in the intercalary segment, and is a regulatory target of the intercalary segment specific Hox gene labial (lab). Loss of Tc col function leads to increased cell death in the intercalary segment. In the milkweed bug Oncopeltus fasciatus, the loss of col function has a more severe effect in lacking the intercalary segment and also affecting the adjacent mandibular and antennal segments. By contrast, col is not expressed early in the second antennal segment in the crustacean Parhyale hawaiensis or in the pedipalpal segment of the spider Achaearanea tepidariorum. This suggests that the early expression of col in a stripe and its role in tritocerebral segment development is insect-specific and might correlate with the appendage-less morphology of the intercalary segment.
authors.affiliation: Georg-August-Universität, Johann-Friedrich-Blumenbach-Institut für Zoologie und Anthropologie, Abteilung Entwicklungsbiologie, GZMB, Ernst-Caspari-Haus, Justus-von-Liebig-Weg 11, 37077 Göttingen, Germany.
authors.forename: Nina D
authors.initials: ND
authors.lastname: Schaeper
authors.forename: Matthias
authors.initials: M
authors.lastname: Pechmann
authors.forename: Wim G M
authors.initials: WG
authors.lastname: Damen
authors.forename: Nikola-Michael
authors.initials: NM
authors.lastname: Prpic
authors.forename: Ernst A
authors.initials: EA
authors.lastname: Wimmer
mesh_terms: D000818:Animals; D001181:Arthropods / Q000235:genetics*; D019521:Body Patterning; D001517:Coleoptera / Q000235:genetics*; D015509:Developmental Biology / Q000379:methods; D029721:Drosophila Proteins / Q000235:genetics* / Q000378:metabolism; D019143:Evolution, Molecular; D018507:Gene Expression Regulation, Developmental; D017403:In Situ Hybridization; D007313:Insecta; D008954:Models, Biological; D010641:Phenotype; D010802:Phylogeny; D034622:RNA Interference; D014157:Transcription Factors / Q000235:genetics* / Q000378:metabolism
chemical_list: D029721:Drosophila Proteins; D014157:Transcription Factors; C104357:kn protein, Drosophila