Fig. 5. The FTO-LINE1 RNA axis plays critical roles during early development.

(A) Number of GV oocytes from 4-week-old WT and Fto^−/− mice. Error bars and means ± SEM are shown for n = 4 WT mice and n = 6 Fto^−/− mice. (B) Ratio of surrounded nucleolus (SN)/nonsurrounded nucleolus (NSN) oocytes from 4-week-old WT mice (n = 5) and Fto^−/− mice (n = 4). (C) Relative LINE1 RNA expression measured by reverse transcription qPCR in WT and Fto^−/− oocytes. (D) Left: DNase I-TUNEL assay showing more closed chromatin in oocytes upon Fto KO. Scale bars, 50 μm. The nucleus was counterstained by DAPI. Representative images were selected from three independent experiments. Right: relative TUNEL intensity in WT and Fto^−/− oocytes (n = 12 each). pSN, partly surrounded nucleolus. (E) Implantation rate (left) and E7.5 embryo rate (right) of Fto^P+/M+, Fto^P+/M−, Fto^P−/M+, and Fto^P−/M− zygotes. (F) Relative LINE1 RNA expression measured by reverse transcription qPCR in Fto^P+/M+ and Fto^P−/M− morulae. For (A), (C), (D), and (F), P values were determined using unpaired two-tailed t tests; error bars and means ± SD are shown for n = 3 experiments in (C) and (F). For (B) and (E), P values were determined using two-tailed z tests.