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

First published online 6 October 2004
doi: 10.1242/dev.01434

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 Related articles in Development 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 Overstreet, E. Articles by Fischer, J. A. Search for Related Content PubMed PubMed Citation Articles by Overstreet, E. Articles by Fischer, J. A. Social Bookmarking                         What's this?

Fat facets and Liquid facets promote Delta endocytosis and Delta signaling in the signaling cells

Section of Molecular Cell and Developmental Biology, Institute for Cellular and Molecular Biology, The University of Texas at Austin, Moffett Molecular Biology Building, 2500 Speedway, Austin, TX 78712, USA

View larger version (122K): [in a new window]   Fig. 1. Delta localization in eye discs. (A-C) Tangential sections through adult eyes are shown. The numbers in A refer to the outer R-cells, R1-R6. (D-F) Confocal images of eye discs labeled with anti-Delta are shown. Anterior is towards the right and the arrows indicate the position of the furrow. (G) A diagram of the early stages of ommatidial assembly. A is anterior, P is posterior; 0-4 at the top indicate columns emerging from the furrow (mf). R-cell identities are indicated by the numbers inside the circles. The red cells may be those that become ectopic R-cells in faf mutants. (H-H'') Enlargement of the boxed region in E. Numbers indicate R-cells and asterisks indicate an ectopic R-cell. In H'', both membrane-bound Delta (yellow) and vesicular Delta (green) are present. Scale bar: 20 µm in A-C; 10 µm in D-F; 5 µm in H-H''.

View larger version (72K): [in a new window]   Fig. 2. faf+ functions in R2/3/4/5. (A,B) Confocal images of GFP expression from a RO-GFP transgene in an eye disc. In A, anterior is towards the right and the arrow indicates the position of the furrow. (B) An enlargement of part of A is shown, the numbers indicating R-cells R2/3/4/5. (C,D) Tabulation of the different phenotypically mutant faf+/fafFO8 mosaic facets with one (C) or two (D) ectopic R-cells are shown. (E) Tabulation of the different phenotypically wild-type faf+/fafBX4 mosaic ommatidia are shown. Numbers beneath each diagram refer to the number of facets with that particular mosaic pattern observed. The faf+ R-cells are white+ (have pigment granules) and the faf- R-cells are white- (do not have pigment granules). (F) Aspects of the data in C-E are displayed graphically. Scale bar: 20 µm in A; 10 µm in B.

View larger version (129K): [in a new window]   Fig. 3. RO-shiDN (A-D) or RO-DlDN (E-H) phenocopy faf mutant eyes. (A,E) Shown are tangential sections through adult eyes of flies expressing the indicated transgenes. (B,F) Confocal images of eye discs labeled with anti-Delta are shown. Anterior is towards the right and large arrows indicate the position of the furrow. (C,D) Enlargements of clusters in B indicated by small arrows. (G,H) Enlargements of clusters in F indicated by small arrows. In C,D,G,H, numbers refer to R-cells and asterisks are ectopic R-cells. Scale bar: 20 µm in A,B,E,F; 10 µm in C,D,G,H.

View larger version (147K): [in a new window]   Fig. 4. Atonal expression in Delta and lqf-null eye disc clones. Eye discs labeled with anti-Atonal are shown. Anterior is upwards. (A,A') A clone of Deltarev10 cells marked by the absence of GFP. (B,B') A clone lqf ARI cells marked by the absence of GFP. Clone borders are outlined in A and B. Scale bar: 10 µm.

View larger version (114K): [in a new window]   Fig. 5. R-cell determination in Delta and lqf-null eye disc clones. Confocal images of eye discs are shown. Anterior is upwards in all panels and the arrows indicate the position of the furrow. The discs contain Deltarev10 clones (A,A',B,B') or lqf ARI clones (C,C',D,D') marked by the absence of GFP. The discs are labeled with anti-Elav in (A,A',C,C') and with anti-Boss in (B,B',D,D'). In A-D, the clone borders are outlined. The Elav and Boss-expressing cells can be seen several cell distances in from the edge of the clone. This is probably due to long-range Delta signaling, a phenomenon that is not well understood (De Joussineau et al., 2003). Scale bar: 10 µm.

View larger version (148K): [in a new window]   Fig. 6. Notch activation in Delta and lqf-null eye disc clones. Confocal images of eye discs in the region of the furrow are shown. Anterior is upwards in all panels. Eye discs are labeled with mAb323, which recognizes E(spl) proteins. (A,A') An eye disc containing a Deltarev10 clone marked by the absence of GFP is shown. In A, the clone is outlined and the asterisks indicate Deltarev10 cells that express E(spl). (B,B') An eye disc containing a lqf ARI clone marked by the absence of GFP is shown. In B, the clone is outlined and the asterisks indicate lqf ARI cells that express E(spl). The clones were examined throughout the depth of the eye disc and most E(spl)-expressing cells are adjacent to clone borders at all levels. Some E(spl)-positive cells are several distances from the clone border (as in A,A'). This may be evidence for long-range Delta signaling, a process that is not well understood (De Joussineau et al., 2003). Scale bar: 10 µm.

View larger version (96K): [in a new window]   Fig. 7. Cell autonomy of Delta mislocalization in lqf null eye disc clones. Confocal images of an eye disc (anterior upwards) containing lqfARI clones, marked by the absence of GFP, is labeled with anti-Delta and with phalloidin, which marks f-actin at cell membranes. The top panel shows Delta localization, the middle panel shows phalloidin, and the bottom panel is a merge of Delta, phalloidin and GFP. Arrows indicate the position of the furrow. Scale bar: 20 µm.

View larger version (80K): [in a new window]   Fig. 8. Role of neur+ in eye patterning. (A,B) Tangential sections of adult eyes are shown. In A, ommatidia with ectopic R-cells (indicated by asterisks) within a clone of neur11 cells. In B, the entire eye is the genotype indicated. (C,C') Eye discs labeled with anti-Delta and phalloidin. (D,D') Eye disc expressing a RO-GFP transgene and labeled with anti-Delta. (E,E') Eye disc containing a clone of neur1 cells marked by the absence of GFP. In E, the clone border is outlined. The arrows in C-E indicate the position of the furrow. (F,F') An eye disc labeled with mAb323 [recognizes E(spl) proteins] containing neur1 clones near the furrow, which are marked by the absence of GFP. In F, the clone borders are outlined and neur1 cells that express E(spl) are marked with asterisks. Discs were observed at depths throughout the apical/basal plane and a few E(spl)-positive cells were found at a distance from the clone borders. Scale bar: 20 µm in A-C'; 15 µm in D-F'.

View larger version (29K): [in a new window]   Fig. 9. Model for Faf, Lqf and Neur function. (A) Early events in ommatidial assembly (see Wolff and Ready, 1993). The morphogenetic furrow (mf) moves in the direction of the arrow. A is anterior and P is posterior. The first several columns (0-4) of developing ommatidia are shown. Atonal-expressing cells are black. R1-R8 are indicated. Three processes (I, II, III) that require Notch/Delta signaling are shown. (I) Proneural enhancement: Atonal expression is upregulated. (II) Lateral inhibition: Atonal expression is limited to groups of 10 cells and ultimately to R8s in column 0. (III) R-cell restriction: R2/3/4/5 precursors signal their neighbors to prevent excessive neural determination. As the ectopic cells in faf mutants appear to arise between R3/4, they may be the orange cells. As depicted by the black bars, Faf is essential only for event III, Lqf is essential for events I, II and III, and Neur is essential for event III but is required to a lesser extent for the events I and II. (B) A model showing how Faf/Lqf may function with Neur in the Delta signaling cells is shown. The blue circles are ubiquitin. Lqf is deubiquitinated by Faf, which increases Lqf levels. Ubiquitination of Delta by Neur may stimulate interactions between Delta and Lqf and thereby facilitate Delta internalization.

CiteULike

Complore

Connotea

Del.icio.us

Digg

Reddit

Technorati

Twitter