brakeless is required for photoreceptor growth-cone targeting in Drosophila.
The R1-R6 subclass of photoreceptor neurons (R cells) in the Drosophila compound eye form specific connections with targets in the optic ganglia. In this paper, we report the identification of a gene, brakeless (bks), that is essential for R1-R6 growth cone targeting. In brakeless mutants, R1-R6 growth cones frequently fail to terminate migration in their normal target, the lamina, and instead project through it and terminate in the second optic ganglion, the medulla. Genetic mosaic analysis and transgene rescue experiments indicate that bks functions in R cells and not within the lamina target region. bks encodes a nuclear protein. We propose that it participates in a gene expression pathway regulating one or more growth cone components controlling R1-R6 targeting.
Rao
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Department of Neurology and Neurosurgery, Centre for Research in Neuroscience, McGill University and the Montreal General Hospital, 1650 Cedar Avenue, Montreal, QC H3G 1A4, Canada. ezdz@musica.mcgill.ca
Pang
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Ruan
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Gunning
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Zipursky
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SL
D000595:Amino Acid Sequence; D000818:Animals; D030801:Animals, Genetically Modified; D002454:Cell Differentiation; D029721:Drosophila Proteins; D004331:Drosophila melanogaster / Q000235:genetics* / Q000254:growth & development; D005123:Eye / Q000294:innervation; D017952:Ganglia, Invertebrate / Q000166:cytology; D020439:Growth Cones / Q000502:physiology*; D019476:Insect Proteins / Q000235:genetics / Q000502:physiology*; D007814:Larva; D008969:Molecular Sequence Data; D009024:Morphogenesis; D009030:Mosaicism; D009414:Nerve Growth Factors / Q000235:genetics / Q000502:physiology*; D010786:Photoreceptor Cells / Q000166:cytology / Q000502:physiology*; D014795:Visual Pathways / Q000254:growth & development
D029721:Drosophila Proteins; D019476:Insect Proteins; D009414:Nerve Growth Factors; C412165:sbb protein, Drosophila