Vol. 172 No. 7, March 27, 2006. Pages 999–1008.

After publication of this manuscript, the authors noticed that two images (Fig. 4 B, top left and middle) had been duplicated from a previous publication (Holway, A.H., C. Hung, and W.M. Michael. 2005. Genetics. 169:1451–1460). Here we provide new images corresponding to these control experiments. The authors apologize for this oversight.