Xenbase Image ID: 129791

FIG 2. Demethylation activity is absent from Xenopus egg cyto- plasm. (A) Sperm nucleus stained with the antibody against 5mC. (B) Sperm nucleus incubated in an interphase egg extract for 45 min still stains well with the 5mC antibody. (C) Sperm nucleus after 90 min of incubation in the extract (corresponding to the time of the first cleavage of the zygote) has the same intensity of 5mC staining as the nuclei in (A) and (B). Note the progressive swelling of the sperm nuclei that reflects chromatin decondensation induced by the egg extract. (D–F) Double fluorescence of the same sperm nuclei as in (A–C), in blue for Dapi and in green for 5mC antibody. (G) Dot blot immunodetection of 5 methyl-cytosine in DNA from oocyte (Oo), blastulae stage 4 (B4), 7 (B7), and stage 12 gastrula (G) Xenopus embryos (upper panel left, in vivo). The amount of 5mC (5 methyl-cytosine) detected by the antibody progressively decreases toward gastrulation (compared to the hybridization signal for total DNA in the right side of the panel). There is no detectable change in the 5mC content of the oocyte and sperm nuclei incubated in interphase egg extract for 0, 45, and 90 min (lower left panel, in vitro). On the right side of the panel, the total DNA in the same spots (as on the left) was detected by DNA hybridization with the Satellite1 probe. Image published in: Stancheva I et al. (2002) Copyright © 2002. Image reproduced with permission of the Publisher, Elsevier B. V. Larger Image Printer Friendly View

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