title: The Tribolium ortholog of knirps and knirps-related is crucial for head segmentation but plays a minor role during abdominal patterning.
abstract: Segment formation in the long germ insect Drosophila is dominated by overlapping gap gene domains in the syncytial blastoderm. In the short germ beetle Tribolium castaneum abdominal segments arise from a cellular growth zone, implying different patterning mechanisms. We describe here the single Tribolium ortholog of the Drosophila genes knirps and knirps-related (called Tc-knirps). Tc-knirps expression is conserved during head patterning and at later stages. However, posterior Tc-knirps expression in the ectoderm is limited to a stripe in A1, instead of a broad abdominal domain covering segment primordia A2-A5 as in Drosophila. Tc-knirps RNAi yields only mild defects in the abdomen, at a position posterior to the abdominal Tc-knirps domain. In addition, Tc-knirps RNAi larvae lack the antennal and mandibular segments. These defects are much more severe than the head defects caused by combined inactivation of Dm-knirps and Dm-knirps-related. Our findings support the notion that the role of gap gene homologs in abdominal segmentation differs fundamentally in long and short germ insects. Moreover, the pivotal role of Tc-knirps in the head suggests an ancestral role for knirps as head patterning gene. Based on this RNAi analysis, Tc-knirps functions neither in the head nor the abdomen as a canonical gap gene.
authors.affiliation: Department of Biology, Section Developmental Biology, Friedrich-Alexander-University Erlangen, Staudtstrasse 5, 91058 Erlangen, Germany.
authors.forename: Alexander C
authors.initials: AC
authors.lastname: Cerny
authors.forename: Daniela
authors.initials: D
authors.lastname: Grossmann
authors.forename: Gregor
authors.initials: G
authors.lastname: Bucher
authors.forename: Martin
authors.initials: M
authors.lastname: Klingler
mesh_terms: D000005:Abdomen / Q000196:embryology; D000818:Animals; D019521:Body Patterning; D003001:Cloning, Molecular; D004268:DNA-Binding Proteins / Q000235:genetics; D029721:Drosophila Proteins / Q000235:genetics; D049750:Genome, Insect; D006257:Head / Q000196:embryology; D018398:Homeodomain Proteins / Q000378:metabolism*; D012097:Repressor Proteins / Q000235:genetics; D014231:Tribolium / Q000196:embryology* / Q000235:genetics / Q000378:metabolism*
chemical_list: D004268:DNA-Binding Proteins; D029721:Drosophila Proteins; D018398:Homeodomain Proteins; D012097:Repressor Proteins; C074089:kni protein, Drosophila