spacer gif spacer gif spacer gif spacer gif spacer gif
QUICK SEARCH:   [advanced]


spacer gif
     Home     Help     Feedback     Subscriptions     Archive     Search     Table of Contents    

This Article
Right arrow Summary Freely available
Right arrow Full Text
Right arrow Full Text (PDF)
Right arrow Alert me when this article is cited
Right arrow Alert me if a correction is posted
Services
Right arrow Email this article to a friend
Right arrow Similar articles in this journal
Right arrow Similar articles in PubMed
Right arrow Alert me to new issues of the journal
Right arrow Download to citation manager
Right arrow reprints & permissions
Citing Articles
Right arrow Citing Articles via Google Scholar
Google Scholar
Right arrow Articles by Grammont, M.
Right arrow Articles by Irvine, K. D.
Right arrow Search for Related Content
PubMed
Right arrow PubMed Citation
Right arrow Articles by Grammont, M.
Right arrow Articles by Irvine, K. D.
Social Bookmarking
Add to CiteULike   Add to Complore   Add to Connotea   Add to Del.icio.us   Add to Digg   Add to Reddit   Add to Technorati   Add to Twitter  
What's this?

Organizer activity of the polar cells during Drosophila oogenesis

Muriel Grammont* and Kenneth D. Irvine{dagger}

Howard Hughes Medical Institute, Waksman Institute and Department of Molecular Biology and Biochemistry, Rutgers The State University of New Jersey, Piscataway NJ 08854, USA
* Present address: INSERM UMR 384, Laboratoire de Biochimie, 28 place Henri Dunant, 63001 Clermont-Ferrand, France



View larger version (22K):

[in a new window]
  		Fig. 1. Schematic of stage 6 (A) and 10 (B) follicles. In all figures, follicles are arranged with anterior towards the left. The arrangement and fates of different cells are indicated by the colors of their nuclei: oocyte (dark brown), nurse cells (light brown), central follicle cells (gray), polar cells (red), stalk cells (light blue), outer border cells (green), stretched cells (pink), centripetal cells (dark blue) and posterior terminal cells (black). Although it is thought that the border, stretched and centripetal cells are specified by stage 6, no markers are available to differentiate them until later.

 


View larger version (76K):

[in a new window]
  		Fig. 6. Polar cells localize the oocyte and establish the AP axis. (A,B) fng mosaic follicles stained with Hoechst (DNA, white) and antibodies recognizing {pi}-MYC (wild-type cells, green) and FasIII (polar cells, red). (A) Stage 6 follicle with no posterior polar cells; the oocyte (asterisk) is at the anterior, in contact with the anterior polar cells (arrow). (B) Stage 5 follicle with ectopic lateral polar cells and no posterior polar cells. The oocyte (asterisk) is ectopically localized, in contact with the lateral polar cells (arrow). (C,D) Germaria stained with phalloidin (F-actin, blue) and antibodies recognizing Bic-D (oocyte, red). (C) Wild type. At stage 1, the oocyte (arrow) is located at the posterior of the cyst (D) fng mosaic marked with {pi}-MYC (fng+ cells, green). In a stage 1 mutant follicle, the oocyte (arrow) is in the center of the cyst. (E,G,I) Wild-type follicles and (F,H,J) fng mosaic follicles stained with X-gal (blue/turquoise, pntS99812 in E,F; kin:lacZ in G,H; nod:lacZ in I,J) and antibodies recognizing FasIII (polar cells, black/brown). In F,H,J, the polar cells (arrow) are ectopically localized to the side of the follicle, but (F) the follicle cells surrounding them adopt a posterior identity, and (H,J) the AP axis of the oocyte (asterisk) is correctly oriented with respect to the polar cells.

 


View larger version (88K):

[in a new window]
  		Fig. 2. Polar cells are required to specify border cells. fng mosaic follicles stained with Hoechst (DNA, white) and antibodies recognizing {pi}-MYC (fng+ cells, green), ß-galactosidase (slbo-lacZ, border cells, red) and FasIII (polar cells, cyan). In all figures, panels marked ' or '' show separate channels of the same follicle. (A) Stage 9 follicle with no fng+ anterior cells. No anterior polar cells are formed and no border cells are specified. Arrowhead indicates posterior polar cells. (B) Stage 10A follicle with only the two polar cells fng+ at the anterior. The polar and outer border cells are specified and properly migrate, even though all outer border cells are fng- (insets).

 


View larger version (95K):

[in a new window]
  		Fig. 3. Polar cells are required to specify stretched cells. (A,B) fng mosaic follicles stained with Hoechst (DNA, white) and antibodies recognizing {pi}-MYC (fng+ cells, green), ß-galactosidase (MA33, stretched cells, red) and FasIII (polar cells, cyan). (A) Stage 9 follicle with no fng+ anterior cells. No anterior polar cells form and no stretched cells are specified. Arrowhead indicates posterior polar cells. (B) Stage 10B follicle with only a few fng+ cells at the anterior, including the polar cells (inset). The polar and stretched cells are specified properly, even though almost all stretched cells are fng-.

 


View larger version (80K):

[in a new window]
  		Fig. 4. Polar cells are required to specify centripetal cells. (A,B) fng mosaic follicles stained with Hoechst (DNA, white) and antibodies recognizing {pi}-MYC (fng+ cells, green), ß-galactosidase (BB127, centripetal cells, red) and FasIII (polar cells, cyan). (A) Stage 9 follicle with no fng+ anterior cells. No anterior polar cells form and no centripetal cells are specified (arrow in A). Arrowhead marks posterior polar cells. (B) Stage 10B follicle with only the two polar cells fng+ at the anterior (inset). The polar and centripetal cells are specified and properly migrate (arrow), even though all centripetal cells are fng-. Faint MYC stain in the anterior is germline expression.

 


View larger version (110K):

[in a new window]
  		Fig. 5. Polar cells are sufficient to specify border cells. Follicles with flip-out clones (marked with GFP, green) expressing constitutively activated Notch (ActN) and stained with Hoechst (DNA, white) and antibodies recognizing FasIII (polar cells, red). The arrows indicate the position of border cell groups. (A) Stage 9 follicle with an anterior group containing one polar cell and two outer border cells, and a posterior group containing two polar cells and six outer border cells. All cells express ActN. (B) Stage 10A follicle with an anterior group containing the only ActN cell, which behaves as a polar cell and migrates with three outer border cells. The posterior group includes the wild-type polar cells and five outer border cells. (C) Stage 9 follicle in which all cells express ActN and one group of border cells forms from four polar cells and 11 outer border cells.

 


View larger version (101K):

[in a new window]
  		Fig. 7. upd is not required for the specification of stretched, centripetal or posterior follicle cells. upd mosaic follicles stained with Hoechst (DNA, white) and antibodies recognizing {pi}-MYC (upd+ cells, green) and FasIII (polar cells, red). (A) Stage 10B follicle with no upd+ anterior cells. The polar cells form (A, arrow) and the stretched (A', surface section, arrow) and centripetal (A'', internal section, arrow) cells are specified. (B) Stage 10B follicle with no upd+ cells at the posterior. The polar cells form (B, arrow), the oocyte is posteriorly localized, and the oocyte nucleus is at the anterior of the oocyte (B', arrow).

 


View larger version (35K):

[in a new window]
  		Fig. 8. Schematic representation of signals required for patterning the follicle. Cells are identified by the color of their nuclei, as in Fig. 1. (A) Germarium. In region IIb, the posterior polar cells contact the oocyte. In region III, the oocyte is at the posterior of the cyst, in contact with the polar cells. (B) Before stage 6, signal(s) from the polar cells (large red arrow) establish terminal fates in surrounding cells. In the anterior, they will become border, stretched or centripetal cells. In the posterior, they will become posterior after receiving the germline Grk signal from the oocyte at stage 6. (C) After stage 6, the posterior cells send an unknown signal to the oocyte (black arrows) to reorganize the cytoskeleton, which establishes the later localization of positional determinants, including mRNAs for bcd (light blue lines), nanos (violet lines) and gurken (brown lines). Grk signaling from the germline to central follicle cells establishes dorsal follicle fate. DPP signaling from the stretched cells (pink arrow) is required to establish centripetal cell fate.

 

Add to CiteULike CiteULike   Add to Complore Complore   Add to Connotea Connotea   Add to Del.icio.us Del.icio.us   Add to Digg Digg   Add to Reddit Reddit   Add to Technorati Technorati   Add to Twitter Twitter    What's this?



© The Company of Biologists Ltd 2002