Drosophila Retinal Patterning


The Drosophila retina is a compound apposition eye composed of some 750 self‐contained eye units with lens, retina and photoreceptors. Study of the Drosophila retina is useful in understanding the general problems of cell cycle regulation, local cell signalling, expression of determinative factors, control of programmed cell death and rearrangement of cells within epithelia.

Keywords: retina; Drosophila; signal transduction; programmed cell death; planar polarity

Figure 1.

Developmentof the eye imaginal disc during the larval third instar. (a) A cobalt sulfidestain shows the morphogenetic furrow (MF) and developing ommatidial clusters(inset). (b) In the morphogenetic furrow, high levels of phosphorylated MAPkinase in the proneural clusters (red; overlap with green is yellow)indicate Ras‐pathway activity in these cells; Atonal expression (green)narrows from these proneural groups to single R8 cells, the firstdifferentiated cells in the eye disc. (c) Specific transcription factors arenecessary to produce the other photoreceptor fates (Boss, a transmembraneprotein, marks R8); ommatidia rotate as they mature. Boss,bride‐of‐sevenless; ro, rough; svp, seven‐up; pros, prospero.

Figure 2.

Pupal eyedevelopment. (a) Schematic of apical eye development beginning with two latelarval ommatidia (right). The arrows indicate the rotation of each ommatidiumwith respect to the equator. The middle two panels depict apical developmentof ommatidia through the pupal stage. Following cone cell differentiation, two1° pigment cells enwrap the four cone cells and these are surrounded byundifferentiated cells. Many of these surrounding cells are removed by PCD,resulting in the hexagonal lattice shown, consisting of three bristle cells,three 3° pigment cells and six 2° pigment cells. The left panel is aschematic of two adult ommatidia, one on each side of the equator. This figureshows the photoreceptor rhabdomeres as they would be seen below the surface ofthe eye. Note the different orientation of the photoreceptor trapezoids withrespect to the equator, a difference not visible at the apical surface (seemiddle panels). (b) An apical view of a late‐pupal retina visualized with anantibody to the membrane‐localized protein, Armadillo.(c) A basal view of a late‐pupal retina visualized as in (b). Secondary cellshave reorganized to form a flower pattern emanating from each axon exit port(aep) directly below each ommatidium. Abbreviations: cc, cone cell;1°, primary pigment cell; 2°, secondary pigment cell;3°, tertiary pigment cell; br or b, bristle group; aep, axonexit port.

Figure 3.

Schematic of adult ommatidium.


Further Reading

Banerjee U, Renfranz PJ, Pollock JA and Benzer S (1987) Molecular characterization and expression of sevenless, a gene involved in neuronal pattern formation in the Drosophila eye. Cell 49: 281–291.

Cagan R (2000) Ross L. Cagan, Ph.D.

[http://molecool.wustl.edu/cagan.html] [Researcher's homepage.]

Cagan R and Ready D (1989a) Notch is required for successive cell decisions in the developing Drosophila retina. Genes and Development 3: 1099–1112.

Freeman M (1997) Cell determination strategies in the Drosophila eye. Development 124(2): 261–70.

Hafen E, Basler K, Edstroem JE and Rubin GM (1987) Sevenless, a cell‐specific homeotic gene of Drosophila, encodes a putative transmembrane receptor with a tyrosine kinase domain. Science 236: 55–63.

Halder G, Callaerts P and Gehring WJ (1995) Induction of ectopic eyes by targeted expression of the eyeless gene in Drosophila. Science 267: 1788–1792.

Heberlein U, Wolff T and Rubin GM (1993) The TGF beta homolog dpp and the segment polarity gene hedgehog are required for propagation of a morphogenetic wave in the Drosophila retina. Cell 75(5): 913–926.

Jarman AP, Grell EH, Ackerman L, Jan LY and Jan YN (1994) Atonal is the proneural gene for Drosophila photoreceptors. Nature 369(6479): 398–400.

Ma C, Zhou Y, Beachy PA and Moses K (1993) The segment polarity gene hedgehog is required for progression of the morphogenetic furrow in the developing Drosophila eye. Cell 75(5): 927–938.

Ready DF, Hanson TE and Benzer S (1976) Development of the Drosophila retina, a neurocrystalline lattice. Developmental Biology 53: 217–240.

Reinke R and Zipursky SL (1988) Cell–cell interaction in the Drosophila retina: the bride of sevenless gene is required in photoreceptor cell R8 for R7 cell development. Cell 55: 321–330.

Thomas BJ, Gunning DA, Cho J and Zipursky L (1994) Cell cycle progression in the developing Drosophila eye: roughex encodes a novel protein required for the establishment of G1. Cell 77(7): 1003–1114.

Tomlinson A and Ready DF (1986) sevenless: a cell‐specific homeotic mutation of the Drosophila eye. Science 231: 400–402.

Wolff T and Ready DF (1991) Cell death in normal and rough eye mutants of Drosophila. Development 113(3): 825–839.

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Spencer, Susan, Brachmann, Carrie, and Cagan, Ross(Mar 2003) Drosophila Retinal Patterning. In: eLS. John Wiley & Sons Ltd, Chichester. http://www.els.net [doi: 10.1038/npg.els.0001511]