Homoeosis in Drosophila: Roles and spatial patterns of expression of the Antennapedia and Sex combs reduced loci in embryogenesis

Temporal and spatial relationships between segmentation and homeotic gene expression in Drosophila embryos: distributions of the fushi tarazu, engrailed, Sex combs reduced, Antennapedia, and Ultrabithorax proteins.

“…Here we present comparative data on the expression of a pairrule segmentation gene, fushi tarazu (ftz), which directs the formation of alternate parasegments (PS) (Wakimoto and Kaufman 1981;Jfirgens et al 1984); a segment polarity gene, engrailed (en), which defines the posterior compartment of each segment (Morata and Lawrence 1975;Kornberg 1981a, b;Komberg et al 1985); and the homeotic genes, Sex combs reduced (Scr), Antennapedia (Antp), and Ultrabithorax (Ubx), which have their major effects on the identity of the labial and first thoracic (Wakimoto and Kaufman 1981;Sato et al 1985), first through third thoracic (Wakimoto and Kaufman 1981;Sato et al 1985), and posterior thoracic and first abdominal segments (Lewis 1978), respectively.…”

Structure of transcripts from the homeotic Antennapedia gene of Drosophila melanogaster: two promoters control the major protein-coding region.

“…Homeotic genes in Drosophila melanogaster control the identity of body segments or parts of segments (27,34,45,54). These genes act in a combinatorial manner; the array of genes active in a particular group of cells controls what type of structure the cells will form.…”

“…Certain dominant mutations in the Antennapedia (Antp) gene, a member of the ANT-C, result in the transformation of antennae into legs. However, the Antp locus normally functions in the thoracic and abdominal regions of the fly and not in the head, both during embryogenesis and during metamorphosis (13,45,53,56). Embryos homozygous for recessive embryonic lethal Antp alleles show partial transformations of the mesothoracic (T2) and metathoracic (T3) segments to prothoracic (T1)/head segments (56).…”

Multiple transcripts from the Antennapedia gene of Drosophila melanogaster.

“…Establishment and maintenance of the identity of tissues in the thoracic segments is the central role of the gene we are studying, the homeotic locus Antennapedia (Antp). Recessive lethal mutations of the Antp locus transform cells of the larval and adult ectoderm in an anterior direction (21,46,54,55,58 How is the Antp gene regulated during development? Antp exhibits a pattern of transcript accumulation which is not only tissue specific but is confined to specific subpopulations of cells within a given tissue (27,29).…”

“…For example, activities of bithorax complex genes appear to repress the transcription of Antp in the third thoracic and first seven abdominal segments (12). Mutations in other genes, such as Sex combs reduced, extra sex combs, and Polycomb, also influence Antp expression either directly or indirectly (46,56,59).…”