Northern blot analyses
A 30–45 µg aliquot of high-quality total RNA (A260/280=2.00) was separated on a 19% polyacrylamide denaturing gel, and then transferred to a Hybond membrane (GE healthcare) for 2 h at 200 mA at 4 °C. In brief, after crosslinking for 5 min with ultraviolet irradiation, the membrane was hybridized overnight at 45 °C with DNA probes (Yu et al., 2011). Washing and autoradiography of the Hybond membrane were performed according to the instructions of the North2South™ Chemiluminescent Hybridization and Detection kit (No.17097, Pierce, Rockford, IL).