11.4.4. Size selection of adapter-ligated fragments

For the size selection of the adaptor-ligated fragments use the E-Gel Electrophoresis System (Invitrogen) and a Size Select 2% precast agarose gel (Invitrogen) as below.

  1. Load each fragmented DNA on two lanes of an E-gel.
  2. Electrophorese using the “Size Select” program for 16 min.
  3. Using a size standard (50bp DNA Ladder, Invitrogen, Cat no. 104 16-014), extract 240bp fragments from the gel.
  4. Pool samples and directly transfer to bisulfite treatment without further purification.