FIG. 11.

SIR2α protein is expressed at high level in two-cell embryos. Wild-type two-cell embryos were recovered from the oviducts 24 h following mating. The zona pellucida was removed, and the embryos were fixed and stained with antibody to SIR2α (panel A) and with Hoechst 33258 (panel B). Vertical stacks of images were captured and subsequently deconvolved. Panel C shows the merged image. Note that the SIR2α protein is exclusively nuclear and that it appears to be excluded from regions of heterchromatin, as identified by intense DNA stain. SIR2α appears to have been excluded from the two polar bodies.