Initial state of the Drosophila eye before dorsoventral specification is equivalent to ventral.
Dorsoventral (DV) patterning is crucial for eye development in invertebrates and higher animals. DV lineage restriction is the primary event in undifferentiated early eye primordia of Drosophila. In Drosophila eye disc, a dorsal-specific GATA family transcription factor pannier (pnr) controls Iroquois-Complex (Iro-C) genes to establish the dorsal eye fate whereas Lobe (L), which is involved in controlling a Notch ligand Serrate (Ser), is specifically required for ventral growth. However, fate of eye disc cells before the onset of dorsal expression of pnr and Iro-C is not known. We show that L/Ser are expressed in entire early eye disc before the expression of pnr and Iro-C is initiated in late first instar dorsal eye margin cells. Our evidence suggests that during embryogenesis pnr activity is not essential for eye development. We present evidence that loss of L or Ser function prior to initiation of pnr expression results in elimination of the entire eye, whereas after the onset of pnr expression it results only in preferential loss of ventral half of eye. We demonstrate that dorsal eye disc cells also become L or Ser dependent when they are ventralized by removal of pnr or Iro-C gene function. Therefore, we propose that early state of the eye prior to DV lineage restriction is equivalent to ventral and requires L and Ser gene function.
Singh
Amit
A
Department of Molecular and Cellular Biology, Baylor College of Medicine, One Baylor Plaza, Houston, TX 77030, USA.
Choi
Kwang-Wook
KW
D000818:Animals; D019521:Body Patterning / Q000235:genetics / Q000502:physiology*; D002135:Calcium-Binding Proteins; D029721:Drosophila Proteins / Q000235:genetics; D004331:Drosophila melanogaster / Q000196:embryology* / Q000254:growth & development; D005123:Eye / Q000196:embryology*; D005136:Eye Proteins / Q000235:genetics; D018507:Gene Expression Regulation, Developmental; D007301:Insect Hormones / Q000235:genetics; D036341:Intercellular Signaling Peptides and Proteins; D000072100:Jagged-1 Protein; D007814:Larva; D008565:Membrane Proteins / Q000235:genetics; D000072099:Serrate-Jagged Proteins; D014157:Transcription Factors / Q000235:genetics; D016335:Zinc Fingers
D002135:Calcium-Binding Proteins; D029721:Drosophila Proteins; D005136:Eye Proteins; D007301:Insect Hormones; D036341:Intercellular Signaling Peptides and Proteins; D000072100:Jagged-1 Protein; C465399:L protein, Drosophila; D008565:Membrane Proteins; C000606278:Ser protein, Drosophila; D000072099:Serrate-Jagged Proteins; D014157:Transcription Factors; C109259:pnr protein, Drosophila