RNA extraction and real-time PCR
Deep-frozen ovarian tissues were treated with RBC lysis buffer (0.15 M NH4Cl, 1 mM KHCO3, and 0.1 mM EDTA) to remove red blood cells, homogenised, and centrifuged for 10 min at 3,000×g. Total RNA was extracted from the follicles using TRIzol, treated with DNAse according to the supplier’s instructions, and quantified by UV spectrophotometry. RNA purity was determined from A260/A280; a value between 1.8 and 2 indicated an RNA purity suitable for further analysis. First-strand cDNA was synthesised by reverse transcription of mRNA using the Oligo (dT) primer and Super Script II Reverse Transcriptase (Invitrogen). Real time (RT)-PCR analysis of 25 μl reaction mixture containing SYBR Green was conducted using the LineGene K system (Bioer Technology, Tokyo, JPN). The primers used for RT-PCR are listed in Supplementary Table 1. The Rotor-Gene Real-Time Software 6.0 was used to analyse the results, and the cycle threshold (Ct) values plotted in logarithmic scale were used to compare RNA expression. Gene expression levels relative to GAPDH (a house-keeping gene) were calculated using the 2-ΔΔCt method.