The extracted was
treated with 5 lL of RNase A (10 mg/ml) at 37 C for 20 min and finally
extracted with phenol:chloroform:isoamyl alcohol (24:25:1)
(Sigma). The DNA pellet was resuspended in 25 ll of TE buffer
(10 mM Tris–HCl and 1 mM EDTA) before electrophoresis in 1.5%
agarose gels (Research Organics Inc., Cleveland, OH) at 100 V for
1 h. The gel was stained with ethidium bromide and visualised under
UV illumination for DNA fragmentation (ladder pattern).