QUICK SEARCH:   [advanced] Author: Keyword(s):
Home     Help     Feedback     Subscriptions     Archive     Search     Table of Contents

First published online 4 October 2006
doi: 10.1242/dev.02593

This Article Summary Full Text Full Text (PDF) Alert me when this article is cited Alert me if a correction is posted Services Email this article to a friend Similar articles in this journal Similar articles in PubMed Alert me to new issues of the journal Download to citation manager Citing Articles Citing Articles via HighWire Citing Articles via Google Scholar Google Scholar Articles by Bras-Pereira, C. Articles by Casares, F. Search for Related Content PubMed PubMed Citation Articles by Bras-Pereira, C. Articles by Casares, F. Social Bookmarking                         What's this?

Odd-skipped genes specify the signaling center that triggers retinogenesis in Drosophila

¹ CABD-Andalusian Centre for Developmental Biology, UPO-CSIC, Sevilla 41013, Spain.
² PDBEB, University of Coimbra, Portugal.
³ IBMC, Porto 4150-180, Portugal.

View larger version (100K): [in a new window]   Fig. 1. Expression of the odd-genes is associated to the margin-peripodial cells of the eye disc during development. (A,B) Schemes of late L2/early L3 (A) and late L3 (B) eye discs. (A) Posterior margin cells trigger retinogenesis in the adjacent eye primordium (ep) by producing Hh. (B) Once triggered, retinal differentiation progresses anteriorly (eye). (C) Cross-section through the line in B shows the peripodial and margin cells (green) overlaying the differentiating eye primordium. (D,E) Confocal images of the posterior region of a third larval stage (L3) disc through the peripodial (Pe, D) and disc proper (Dp, E) layers, stained with phalloidin-FITC and Elav (a photoreceptor marker used in this and following figures). The margin (ma) is a thin strip of cells adjacent to the posterior-most row of photoreceptors. (F) Confocal z-section through the same disc showing the three cell types (schematized below). (G) Confocal z-section through the posterior region of a L3 odd-GAL4>GFP disc, co-stained with Eya. odd is restricted to the Pe and margin. (H-O) Patterns of expression of the four odd genes in L2 (H-K) and L3 (L-O). Expression of odd is monitored by the odd-GAL4 reporter (H, left; L) or with an anti-Odd antibody (H, right), and that of drm (I,M), bowl (J,N) and sob (K,O) by RNA in situ hybridization. The patterns of drm and odd seem identical. (H, left) Propidium iodide marks nuclei. (H, right) Rhodamine-phalloidin stains actin. (L) Arm expression marks cell membranes. Arrowheads indicate the margins. Discs are oriented with posterior towards the right and dorsal upwards.

View larger version (68K): [in a new window]   Fig. 2. bowl is required specifically at the margin for retinal triggering and hh expression. Clones are marked by the absence of GFP (A-E) or CD2 (F). (A-E) bowl- clones spanning the posterior margin. (A, inset in B) Defective retinal initiation is associated with bowl- mutant margin (arrow). Retinal initiation is partially rescued non-autonomously by neighboring tissue (clone outlined in B). (C,C') bowl- clone spanning the margin loses hh-Z autonomously (arrow; clone outlined in C'). (D,D') The expression of Ptc is also reduced in a bowl- clone (arrow). (E,E') Internal bowl- clone abutting, but not including, the margin develops retina normally (clone outlined in E'). The hh-Z margin expression (arrow) is normal. (F,F') lines-expressing clone at the margin resembles loss of bowl, causing loss of margin hh-Z and retinal failure (arrow). The hh-Z ocellar expression is not affected (asterisk). Discs are oriented with posterior towards the right and dorsal upwards.

View larger version (91K): [in a new window]   Fig. 3. drm and odd regulate hh expression, probably through enabling bowl function. (A,B) Eye discs containing M+ clones mutant for (A) drm6 or (B) DfdrmP2 (marked by absence of lacZ). (A) No effect on retinogenesis or Ptc expression is seen adjacent to drm-mutant margin. (Similar results were obtained for odd5.) (B) Retinogenesis fails when the adjacent margin is mutant for DfdrmP2. White and red arrows indicate mutant and wild-type margin, respectively. (C) Adult head from the DfdrmP2, M+ experiment showing severely reduced eyes. (D,D') drm-expressing clone (absence of CD2, and outlined in D') induces an ectopic furrow (marked by dpp-Z) and associated retinogenesis (detected by Elav). The line indicates the position of the endogenous furrow (D). (E) Disc proper (Dp) expression of bowl mRNA is detected anterior to the furrow (line) in late L3 discs. (F-F") drm+ bowl- clones (blue) do not induce ectopic retinal differentiation anterior to the morphogenetic furrow (arrow; line indicates the furrow). Phalloidin stains actin. A drm+ bowl- clone located immediately after the furrow (boxed) shows Elav-positive neurons (inset). (G-G") L2 eye disc from oddZ/UAS-GFP; hh-GAL4 larvae shows extensive overlap of hh and odd at the posterior margin. Asterisk indicates the hh ocellar domain, which, at this stage, does not express odd-Z. (H-H") Most drm-expressing clones (absence of CD2, outlined in H' and H'') induce hh-Z expression just anterior to the morphogenetic furrow (line). Discs are oriented with posterior towards the right and dorsal upwards.

View larger version (87K): [in a new window]   Fig. 4. wingless represses drm transcription in anterior eye disc margin. (A,B) Early and (C-F) late L3 discs. (A) In wg-Z discs (ß-galactosidase, orange), prior to the initiation of retinal differentiation, drm and wg expressions are complementary. (C) In late L3 discs, this complementarity is maintained with the exception of the appearance of a dorsal head drm-expressing patch (asterisk in C,D,F). (B) In early L3 wgCX3 discs, drm transcription extends dorsally to reach the antenna (black arrowhead) before retinogenesis starts. (D) In older discs, ectopic retinogenesis (red arrowhead) can be seen progressing from the drm-expressing anterior margin (black arrowhead). (E) Dorsal margin of an odd-GAL4/wg-Z; UAS-GFP L3 disc. odd reporter expression (green and outlined in by the green line in the single channel panels) is complementary to both wg transcription (wg-Z) and protein expression (Wg). (F) A late wild-type L3 disc stained for drm and Elav is shown for comparison. Discs are oriented with posterior towards the right and dorsal upwards.

CiteULike

Complore

Connotea

Del.icio.us

Digg

Reddit

Technorati

Twitter