Figure 3. SIRT6 knockdown in oocytes results in the developmental delay of early embryos. (A) Schematic presentation of the SIRT6-knockdown experiments. (B) Efficiency of SIRT6 knockdown (SIRT6-KD) after siRNA injection was verified by immunoblotting. Tubulin served as a loading control. Band intensity was calculated using Image J software. (C) Representative contrast images of blastocyst embryos derived from control and SIRT6-KD oocytes. Red arrows indicate the developmental delay. (D) The percentage of zygotes that successfully progressed to the blastocyst stage during in vitro culture (n= 65 for control; n=55 for SIRT6-KD). Data are expressed as mean percentage ± SD of three independent experiments. Statistical analyses were performed with Student’s t-test. **P <0.01.