Shearing DNA

Ian A. York iayork at
Sun May 4 17:03:17 EST 1997

I've purified some DNA that's larger than 30,000 bp.  I want to shear it
down to fragments of between 1000-5000 bp.  (For various reasons I want to
do this mechanically, rather than using restriction ensymes.)  I've been
trying passing the DNA through a needle, but I seem to be having trouble
getting the right size out.  For example, passing the DNA through a
26-gauge needle 10 times produces DNA that seems smaller than the
original, but it's still >10 kb.  But passing through a 28-gauge needle 4
times produces very small fragments, <500 bp.  

As you can imagine, I don't have an infinite amount of this prep for
trial-and-error shearing.  Does anyone have a guaranteed, tested and
consistent procedure?  Or is trial and error the only way to go?


      Ian York   (iayork at  <>
      "-but as he was a York, I am rather inclined to suppose him a
       very respectable Man." -Jane Austen, The History of England

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