Fig. 1

Fluctuation of CFP1 protein levels in oocyte meiosis and zygotic cleavages. a Immunofluorescence of trimethylated histone H3K4 (H3K4me3) on chromatin spreads made from postnatal day-21 mouse oocytes, which contained both non-surrounded nucleolus (NSN) and surrounded nucleolus (SN) type of chromatin configuration. More than eight oocytes of each type were observed with similar results. Scale bar, 5 μm. b Quantification of the H3K4me3 signal in (a). Numbers (n) of oocytes being quantified at each developmental stage are indicated. Error bars, S.E.M. ***P < 0.001 by two-tailed Student’s t tests. c Western blot results showing levels of the indicated proteins during oocyte in vitro maturation process. The constitutively expressed DDB1 was blotted as a loading control. Total proteins from 100 oocytes were loaded in each lane. d Relative levels of the indicated histone modifications normalized to the internal control (DDB1), corresponding to the results in (c). e, f Western blot results showing CFP1 levels during G2-M transition in maturing mouse oocytes (e) and the first mitosis in fertilized eggs (f). IVF in vitro fertilization. g CFP1 immunofluorescence results in mouse oocytes, zygotes, and preimplantation embryos. α-tubulin was co-stained to indicate dividing cells. Scale bars, 20 μm