1.Pour a vertical acrylamide gel using TEA buffer.A 4 % non denaturing gel is correct for most applications.

2.Run out DNA fragments.For fragments greater than 500 bp,run the xylene cyanol dye to the bottom.

3.Stain gel for one hour in buffer containing 1μg/ml ethidium bromide.Cut out relevant bands with a scalpel and transfer to 15 or 30 ml Corex tubes.

4.Add TE buffer to tubes; 3 ml for a 15 ml tube; 7 ml for a 30 ml tube.

5.Grind up the gels in a tissue homogenizer for 10".Wash the homogenizer probe first with water,then EtOH both before and after use.

6.Place the tubes at 4 deg.O/N.

7.Spin down acrylamide particles 10K,10',room temp,swing out rotor.Carefully pipet off supernate into a fresh Corex tube.Ethanol precipitate the DNA.