title: Homeotic complex and teashirt genes co-operate to establish trunk segmental identities in Drosophila.
abstract: Homeotic genes determine the identities of metameres in Drosophila. We have examined functional aspects of the homeotic gene teashirt by ectopically expressing its product under the control of a heat-shock promoter during embryogenesis. Our results confirm that the gene is critical for segmental identity of the larva. Under mild heat-shock conditions, the Teashirt protein induces an almost complete transformation of the labial to prothoracic segmental identity, when expressed before 8 hours of development. Positive autoregulation of the endogenous teashirt gene and the presence of Sex combs reduced protein in the labium explain this homeosis. Patterns in the maxillary and a more anterior head segment are partly replaced with trunk ones. Additional Teashirt protein has no effect on the identity of the trunk segments where the gene is normally expressed; teashirt function is overridden by some homeotic complex acting in the posterior trunk. Strong heat-shock regimes provoke novel defects: ectopic sense organs differentiate in posterior abdominal segments and trunk pattern elements differentiate in the ninth abdominal segment. Teashirt acts in a partially redundant way with certain homeotic complex proteins but co-operates with them for the establishment of specific segment types. We suggest that Teashirt and HOM-C proteins regulate common sets of downstream target genes.
authors.affiliation: Laboratoire de Génétique et Physiologie du Développement, CNRS, Université d'Aix-Marseille II, France.
authors.forename: P
authors.initials: P
authors.lastname: de Zulueta
authors.forename: E
authors.initials: E
authors.lastname: Alexandre
authors.forename: B
authors.initials: B
authors.lastname: Jacq
authors.forename: S
authors.initials: S
authors.lastname: Kerridge
mesh_terms: D000818:Animals; D030801:Animals, Genetically Modified; D004330:Drosophila / Q000196:embryology* / Q000235:genetics; D005786:Gene Expression Regulation / Q000502:physiology; D005801:Genes, Homeobox / Q000502:physiology*; D017344:Genes, Insect / Q000502:physiology*; D006358:Hot Temperature; D017403:In Situ Hybridization; D009024:Morphogenesis / Q000235:genetics