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Figure 3 | BMC Biology

Figure 3

From: The eggshell is required for meiotic fidelity, polar-body extrusion and polarization of the C. elegansembryo

Figure 3

gna-2(qa705) has normal meiotic timing, but fails to extrude polar bodies and has 12 sister chromatids at meiosis II. In utero recording of (A) wild-type embryo expressing tubulin::GFP, showing first meiotic spindle (top row) and second meiotic spindle (bottom row) or (B) gna-2(qa705) embryo expressing tubulin::GFP, showing first meiotic spindle (top row) and second meiotic spindle (bottom row). (B,C) Times are from entry into the spermatheca. (C) Time from entry into spermatheca until waning of first meiotic spindle (bars 1,2), from waning of first meiotic spindle until waning of second meiotic spindle (bars 3,4) or total time from entry into spermatheca until waning of second meiotic spindle (bars 5,6), in wild-type embryos expressing tubulin::GFP, (n = 3) or gna-2(qa705) embryos expressing tubulin::GFP, (n = 4). Bars are mean ± SEM. For each comparison, gna-2(qa705) was not significantly different from wild type (p > 0.05). (D) gna-2(qa705) expressing histone H2B::GFP, showing meiotic DNA segregation. Times are from entry into the spermatheca. Large, black and white image (4-min time point) shows the embryo in utero, with the box indicating the maternal DNA shown enlarged (GFP signal) in the upper right hand corner. Unextruded second polar body is indicated by a red asterisk at the 30 and 34 min time points, and maternal and paternal pronuclei, which have met, are indicated by a yellow asterisk at the 30- and 34-min time points. (A,B,D) White line indicates embryonic cortex. (E) gna-2(qa705) expressing histone H2B::GFP, showing stray chromatin (red arrow) (distinct from two major masses segregated at meiotic anaphase II). (F) Time from entry into spermatheca until meiotic anaphase I (bars 1–4), until meiotic anaphase II (bars 5–8) or until pronuclear meeting (bars 9–12), in wild type (n = 11), gna-2(qa705) (n = 13), chs-1(RNAi) (n = 9) or cej-1+B0280.5(coRNAi) (n = 14), expressing histone H2B::GFP. Bars are mean ± SEM. For each comparison (wild type, gna-2(qa705), chs-1(RNAi) and cej-1+B0280.5(coRNAi)) there were no significant differences (p > 0.05).

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