Preparation of Herring Sperm DNA for Southern Blotting

1. order powder herring sperm DNA from Boehringer Mannheim (#223646 for 1 gram)

2. dissolve 0.250 g in 25 ml of ddH₂O (use 50 ml conical tube) overnight at room temperature

3. sonicate for 15 minutes on setting #4 (or several seconds on setting #7-9)

4. shear through 18-gauge needle 10 times or more (until solution moves easily through needle)

5. store in labeled box (common) at –20ºC in 1 ml aliquots