Synergy between the hunchback and bicoid morphogens is required for anterior patterning in Drosophila.
Anterior patterning of the Drosophila embryo is specified by the localized expression of the gap genes, which is controlled by the gradient of the maternal morphogen bicoid (bcd). Another maternal component, hunchback (hb), can substitute for bcd in the thorax and abdomen. Here we show that hb is required for bcd to execute all of its functions. Removal of both maternal and zygotic hb produces embryos with disrupted polarity that fail to express all known bcd target genes correctly. Proper expression of hb and the head gap genes requires synergistic activation by hb and bcd. We propose that it is the combined activity of bcd and hb, and not bcd alone, that forms the morphogenetic gradient that specifies polarity along the embryonic axis and patterns the embryo. bcd may be a newly acquired Drosophila gene, which is gradually replacing some of the functions performed by maternal hb in other species.
Simpson-Brose
M
M
Howard Hughes Medical Institute, Rockefeller University, New York, New York 10021-6399.
Treisman
J
J
Desplan
C
C
D000005:Abdomen / Q000196:embryology; D000818:Animals; D030801:Animals, Genetically Modified; D001483:Base Sequence; D003433:Crosses, Genetic; D004268:DNA-Binding Proteins; D004330:Drosophila / Q000033:anatomy & histology / Q000196:embryology*; D029721:Drosophila Proteins; D047108:Embryonic Development; D005260:Female; D017344:Genes, Insect; D006257:Head / Q000196:embryology; D018398:Homeodomain Proteins; D017403:In Situ Hybridization; D007301:Insect Hormones / Q000378:metabolism*; D007605:Juvenile Hormones / Q000302:isolation & purification / Q000378:metabolism*; D008297:Male; D008969:Molecular Sequence Data; D009024:Morphogenesis; D012333:RNA, Messenger / Q000032:analysis; D013909:Thorax / Q000196:embryology; D015534:Trans-Activators; D014157:Transcription Factors
D004268:DNA-Binding Proteins; D029721:Drosophila Proteins; D018398:Homeodomain Proteins; D007301:Insect Hormones; D007605:Juvenile Hormones; D012333:RNA, Messenger; D015534:Trans-Activators; D014157:Transcription Factors; C056478:bcd protein, Drosophila; C061245:hb protein, Drosophila