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Science 321 (5896): 1683-1686

Copyright © 2008 by the American Association for the Advancement of Science

Apoptotic Force and Tissue Dynamics During Drosophila Embryogenesis

Yusuke Toyama1, Xomalin G. Peralta1*, Adrienne R. Wells2, Daniel P. Kiehart2{dagger}, and Glenn S. Edwards1{dagger}

1 Physics Department and Free Electron Laser Laboratory, Duke University, Durham, NC 27708, USA.
2 Department of Biology, Duke University, Durham, NC 27708, USA.


Figure 1 Fig. 1.. Dorsal closure in control and apoptotically altered GFP-moe–expressing embryos. Confocal fluorescent images of (A) control, (B) AS-p35, and (C) AS-grim embryos are shown (AS, amnioserosa; LE, lateral epidermis). Anterior is to the left in all figures. Scale bar, 50 µm. (D) Rapoptosis for control (black), AS-p35 (white), and AS-grim (gray) embryos; error bars indicate SD. A single or double asterisk indicates that the value is significantly different from the control value at P < 0.05 and P < 0.01, respectively. (E) Plot of H(t) as a function of time for embryos that were shown in (A) to (C), respectively. (F) Correlation between vnative and Rapoptosis (each normalized by the average value for control embryos as indicated by overbars, correlation coefficient r = 0.941). [View Larger Version of this Image (72K GIF file)]
 

Figure 2 Fig. 2.. Fate of apoptotic amnioserosa cells and the distortion of the surrounding cells in wild-type embryos. (A) Confocal sections through GFP-moe–expressing embryos, where rows indicate depth below the surface and columns indicate time (as shown). Accumulation of F-actin is evident on the surface of one amnioserosa cell at time 0 s (arrow). Contraction occurs between 0 and 1500 s (arrows). Cell extrusion is evident at all depths at 1500 s (arrows). Blebbing is evident 7.90 µm below the surface at 2100 s (arrow). Scale bar, 10 µm. (B) Color-enhanced reproduction of the surface images from (A). The red cells are pulled toward the apoptotic cells (white), rearrange their neighbor-neighbor configurations, and fill the gap. The blue cell does not change shape as dramatically but is distorted and pulled toward the apoptotic cell. (C) Schematic representation indicating the region of the amnioserosa imaged in (A) (not to scale). [View Larger Version of this Image (137K GIF file)]
 

Figure 3 Fig. 3.. Experimental determination of {sigma}AS. (A) Edge-cut protocol of a wild-type embryo expressing GFP-moe: Shown are the location of the edge cut (dashed line), which commenced at t = 0 s, and the morphology at the turning point. Scale bar, 50 µm. (B) Correlation between {sigma}AS and Rapoptosis (each normalized by the average value for control embryos, r = 0.997). Points are average values for control (black), AS-p35 (white), and AS-grim (gray) embryos normalized by the average value for control embryos as indicated by overbars; error bars indicate SD. [View Larger Version of this Image (39K GIF file)]
 

Figure 4 Fig. 4.. Apoptosis contributes to the zipping rate. (A) Plot of total seam length wA + wP for controls (black), AS-p35 (white), and AS-grim (gray) for the embryos shown in Fig. 1, A to C. (B) Histogram of kz,A and kz,P and (C) spatial distribution of Rapoptosis in control (black), AS-p35 (white), and AS-grim (gray) embryos (*P < 0.05; **P < 0.01); error bars indicate SD. The dorsal opening was segmented by taking thirds of the canthus-to-canthus distance [inset in (C)]. (D) Correlation between kz and Rapoptosis [each normalized by the average value (kz,A and kz,P or Rapoptosis_Ant and Rapoptosis_Pos) for controls as indicated by the overbars, r = 0.802]. [View Larger Version of this Image (24K GIF file)]
 


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