Fig. 2. zyg-11 is required for timely metaphase to anaphase transition and M phase exit at meiosis II. (A-N) Lateral views of wild-type or zyg-11(RNAi) embryos at the indicated stages, stained with antibodies against -tubulin (A-C,G-J), or -tubulin and phosphorylated histone H3 (D-F,K-N). Insets below panels A-C and G-J, as well as the entire panels D-F and K-N are magnified views of a meiotic spindle and have a width of 7 µm. Insets below panels A-C and G-J show -tubulin (green) and DNA (blue) on the left, and DNA alone on the right. Panels D-F and K-N show -tubulin (green), phosphorylated histone H3 (red) and DNA (blue) on the left, and phosphorylated histone H3 alone on the right. To view polar bodies and sperm chromosomes, the DNA signal in the low magnification images is a projection of several 1-µm confocal optical sections. Arrowheads point to the first polar body, arrows indicate condensed sperm DNA. Scale bar: 10 µm. Note that the focus of phosphorylated H3 lies between homologues at metaphase I and sister chromatids at metaphase II in both wild-type and zyg-11(RNAi) embryos. (O,P) Wild-type (O) and zyg-11(RNAi) (P) anaphase II embryos expressing GFP-CYB-3 stained with antibodies against -tubulin (not shown) and GFP (red); DNA is shown in blue. (Q) Quantification of signal intensities in wild-type (n=6), zyg-11(RNAi) (n=14) and cul-2(RNAi) (n=19) embryos in metaphase II or anaphase II stained as in (O); embryos were staged using the anti--tubulin and DNA signals. The difference between wild type and zyg-11(RNAi) or cul-2(RNAi) is statistically significant (Student's t-test: P=6x10^-5 and P=4x10^-6, respectively).