10 ml collected EDTA blood is mixed with 30 ml DNA lysis buffer and left in
a 50 ml polypropylene screw-cap tube (Falcon) on crashed ice for one hour. After
centrifuging for 15 minutes at 1500 rpm (4psy176 C), the supernatant is decanted,
the pellet (white blood cells) resuspended in 10 ml DNA lysis buffer and
centrifuged again for 10 minutes at 1500 rpm (4psy176 C). The supernatant is
decanted again and the pellet resuspended in 5 ml 1 
SE buffer. 0.25 mg
Proteinase K and 250 
l 20% SDS are added and incubated overnight at
37psy176 C.
1.5ml saturated NaCl (6M) are added, shaken and centrifuged for 20 minutes at
17000 rpm. The supernatant is decanted into a fresh tube, centrifuged once
again and transferred to a fresh tube again. Two volumes absolute alcohol are
added to precipitate DNA
. Large
pieces of DNA can be removed by collecting fibres with a glass rod and
transferring them to a new tube. Again, 1 ml absolute ethanol is added,
centrifuged and the supernatant decanted. The pellet is washed with 200 l
70% ethanol, centrifuged shortly, decanted and desiccated in a vacuum
evaporator (Speed Vac).