Organization of the Drosophila head as revealed by the ectopic expression of the Ultrabithorax product.
By using a hsp70-Ubx fusion gene, we have ectopically expressed a Ubx product in the embryonic head primordia and studied the developmental effects on the larval head. We find that after high and persistent levels of Ubx product, the head is replaced by three (C1, C2 and C3) abdominal-like denticle belts. The C2 and C3 belts are the homeotic transformations of parasegments 1 and 2, respectively, while the C1 belt probably derives from the transformation and subsequent fusion of the most anterior procephalic primordia. On the basis of their response to the Ubx product and other arguments, we propose that the larval head is made of two genetically distinct components; one is the procephalon and the anterior region of the mandibular lobe, and the other is part of the parasegmental trunk and includes parasegments 1 and 2. Our results also indicate that most or all the larval head structures derive from precursor cells of ventral origin.
Centro de Biología Molecular (CSIC-UAM), Universidad Autónoma, Madrid, Spain.
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González-Reyes
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Morata
D000818:Animals; D004268:DNA-Binding Proteins / Q000235:genetics*; D004330:Drosophila / Q000196:embryology* / Q000235:genetics / Q000648:ultrastructure; D029721:Drosophila Proteins; D015870:Gene Expression / Q000502:physiology*; D005801:Genes, Homeobox / Q000235:genetics*; D006257:Head / Q000196:embryology* / Q000502:physiology; D018398:Homeodomain Proteins; D006358:Hot Temperature / Q000009:adverse effects; D009024:Morphogenesis / Q000235:genetics*; D009154:Mutation / Q000235:genetics; D014157:Transcription Factors
D004268:DNA-Binding Proteins; D029721:Drosophila Proteins; D018398:Homeodomain Proteins; D014157:Transcription Factors; C066177:Ubx protein, Drosophila