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

First published online 5 November 2003
doi: 10.1242/dev.00854

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 Tran, D. H. Articles by Berg, C. A. Search for Related Content PubMed PubMed Citation Articles by Tran, D. H. Articles by Berg, C. A.

bullwinkle and shark regulate dorsal-appendage morphogenesis in Drosophila oogenesis

Department of Genome Sciences, University of Washington, Box 357730, Seattle, WA 98195-7730, USA

View larger version (78K): [in a new window]   Fig. 1. Deficiencies significantly modified the bwk DA phenotype. DIC images of stage-14 egg chambers. (A) Canton S egg chamber exhibiting two long, tubular DAs (bracket). (B) bwk151/bwk8482 egg chamber with shortened and broadened DAs (bracket). Note the remnant nurse-cell material caused by a defect in nurse-cellcytoplasmic transport (asterisk). (C) In(2L)pk78s/+; bwk151/8482 egg chamber exhibiting suppression of the DA defect. The amount of remnant nurse-cell material is unchanged (asterisk). (D) Df(2R)Jp8/+; bwk151/8482 egg chamber showing an enhanced bwk DA defect. The DA length is reduced and the shape of the appendage is altered. This deletion uncovers the gene shark. Scale bars: 100 µm.

View larger version (142K): [in a new window]   Fig. 2. shark expression is altered in bwk mutants. In situ hybridization of egg chambers probed with antisense shark RNA in Canton S (A,C,C') and in bwk151/8482 egg chambers (B,D,D'). (A) In early oogenesis, shark RNA is expressed in all tissues, with higher levels in the germline. (C) Surface view. At stage 10, shark RNA accumulates in darkly staining concentrations at the periphery of nurse cells. Boxed area shows RNA foci associated with stretch-cell nuclei. Faint expression in the columnar cells over the oocyte is also seen. (C') Magnified view of the boxed area in C. Arrowheads indicate stretch cell nuclei. (B) In bwk egg chambers, the RNA appears more diffuse, although levels are comparable with wild type. (D) At stage 10, the concentrated RNA foci at the anterior are greatly reduced (compare with C). (D') Magnified view of area outlined by blue box in D. Arrowhead indicates stretch cell nucleus. Scale bars: 100 µm.

View larger version (117K): [in a new window]   Fig. 3. Stretch cells are a substrate for DA-forming cells and exhibit morphogenetic behaviors. Confocal images of Canton-S egg chambers expressing UAS-GFPS65T in the stretch cells and a nuclear ß-galactosidase in the anterior columnar cells. (A,A',C,E) Anti-GFP, (B,B',D,F) merge of anti-GFP (green) and anti-ß-gal (red) images. (A,B) The stretch cells cover the exterior of the nurse cells. The posterior-most stretch cells (asterisk in A) move inwards along with the centripetally migrating columnar cells. In the lower right of panels A and B, centripetal migration is commencing in a stage-10B egg chamber (white arrow in B). (A',B') Magnified views of the boxed areas in A,B show that the stretch-cell layer is thickest near the stretch-cell nuclei (blue triangle, A') and at the valleys between nurse cells (blue arrowhead, A'). (C,D) Stretch-cell staining is present around the shrinking nurse cells (NC). The DA-forming cells have formed a tube and are moving anteriorly on the stretch cells (green arrowhead, C). (E,F) A magnified view of an interface between the front of a DA-cell wedge and the stretch cells at stage 12. Note the thin cellular projections extending towards the DA cells (arrow). Scale bars: 25 µm.

View larger version (74K): [in a new window]   Fig. 4. shark follicle-cell mosaics produce two distinct DA phenotypes. (A,B) DIC images of shark1-mosaic egg chambers. (A) DA chorion defect. (B) Short DA with normal chorion. (C-F) DIC and confocal images of a single egg chamber in which only the shark1 clonal cells are GFP positive. GFP-positive cells are green and anti--Spectrin in red shows cell membranes. Asterisk in C indicates abnormal `thumb' of chorion in anterior of the right DA (C,D). The left DA (E,F) is vacuolated. (G) Diagrams of six confocal z slices taken 3 µm apart of egg chamber in C-F. Arrows indicate the corresponding z slice for the two confocal images shown. GFP-positive cells are labeled green. A region where the cell boundary is indeterminate is shown in purple. shark1 clonal cells lie between the two DA arms or are closely associated with the DA shown in E,F. (H) Table showing frequency of clones and defects.

View larger version (68K): [in a new window]   Fig. 5. bwk, shark and Jun interactions in oogenesis. (A,B) UAS-shark+ suppresses the bwk151/8482 phenotype when expressed in stretch-cells. (A) DIC image of bwk151/8482 DA phenotype. (B) DIC image of UAS-shark+ mediated suppression of bwk151/8482 DA phenotype: DAs are longer and more tube-like. (C,D) Jun expression is unchanged in bwk. (C) Image of a wild-type stage-10 egg chamber showing immunofluorescence of the Drosophila Jun pattern in follicle cells. (D) Merged confocal image showing anti-Jun staining in a stage 10 egg chamber with a large shark clone (GFP-negative cells) covering most of the anterior follicle cells, including the stretch and DA-forming cells. Jun expression is unchanged.

View larger version (46K): [in a new window]   Fig. 6. Model of bwk and shark interactions. (A) Shark expression is regulated by BWK function in the germline. Shark activity in the stretch cells is required for the proper anterior movement of the DA-forming cells as they move anteriorly. (B) bwk and shark interactions. Shark in the stretch cells regulates DA-cell movement, while Shark in the DA-forming cells regulates synthesis of the DA chorion. The suppression of bwk by SRC42A stretch-cell expression suggests that this protein may function alongside Shark to mediate DA-cell movement.