Article Abstract:
Photoreceptor axons approaching the Drosophila brain organize their postsynaptic target field into a precise array of five neuron cartridge groups. Hedgehog, an initial inductive signal transported along retinal axons from the developing eye, was found to cause postsynaptic precursor cells to express the Drosophila homolog of the epidermal growth factor receptor (EGFR). The EGFR ligand Spitz is transferred to retinal axon termina in the brain where it functions as a local cue for the recruitment of five cells into a cartridge group.
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Article Abstract:
The process of dorsal-ventral (DV) polarity in the embryo depends on the expression of pipe in the somatic tissue of the Drosophila ovary. To determine the formation of embryonic DV axis, a candidate pipe locus that encodes an enzyme with similarity to hefaran sulfate 2-0-sulfotransferase and expressed in the ventral follicle cells of the egg chamber was identified. The results of the molecular cloning of this transcription unit and their implications are discussed.
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Article Abstract:
Morphogenesis of the Drosophila eggshell requires paracrine activation by the transforming growth factor-alpha homolog Gurken, positive feedback through Rhomboid and Spitz and self-inhibition by the protein Argos. These homologs form a novel patterning activity in the ovarian follicular epithelium that transforms a single domain of the epidermal growth factor receptor signaling into twin peaks of activation that are required for the activity.
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