Interaction of gap genes in the Drosophila head: tailless regulates expression of empty spiracles in early embryonic patterning and brain development.
Unlike gap genes in the trunk region of Drosophila embryos, gap genes in the head were presumed not to regulate each other's transcription. Here, we show that in tailless (tll) loss-of-function mutants the empty spiracles (ems) expression domain in the head expands, whereas it retracts in tll gain-of-function embryos. We have identified a 304bp element in the ems-enhancer which is sufficient to drive expression in the head and brain and which contains two TLL and two BCD binding sites. Transgenic reporter gene lines containing mutations of the TLL binding sites demonstrate that tll directly inhibits the expression of ems in the early embryonic head and the protocerebral brain anlage. These results are the first demonstration of direct transcriptional regulation between gap genes in the head.
Hartmann
B
B
Institute of Zoology, University of Basel, Rheinsprung 9, 4051, Basel, Switzerland.
Reichert
H
H
Walldorf
U
U
D000818:Animals; D030801:Animals, Genetically Modified; D001483:Base Sequence; D001665:Binding Sites; D001921:Brain / Q000196:embryology* / Q000378:metabolism / Q000502:physiology*; D004268:DNA-Binding Proteins / Q000502:physiology*; D003850:Deoxyribonuclease I / Q000378:metabolism; D004330:Drosophila; D029721:Drosophila Proteins; D004475:Ectoderm / Q000378:metabolism; D004742:Enhancer Elements, Genetic; D017930:Genes, Reporter; D018398:Homeodomain Proteins / Q000502:physiology*; D007150:Immunohistochemistry; D017403:In Situ Hybridization; D018613:Microscopy, Confocal; D008957:Models, Genetic; D008969:Molecular Sequence Data; D009154:Mutation; D009474:Neurons / Q000378:metabolism; D012097:Repressor Proteins / Q000502:physiology*; D014158:Transcription, Genetic; D019076:Transgenes; D000099260:Empty Spiracles Homeobox Proteins
D004268:DNA-Binding Proteins; D003850:Deoxyribonuclease I; D029721:Drosophila Proteins; D018398:Homeodomain Proteins; D012097:Repressor Proteins; C074090:TLL protein, Drosophila; C093054:ems protein, Drosophila; D000099260:Empty Spiracles Homeobox Proteins