random shear

"Marianne Leverone ", BIO leverone at CHUMA.CAS.USF.EDU
Fri Jun 16 08:47:37 EST 1995

Dear Maria:  When our lab was studying natural transformation, the 
graduate student working on that project used to shear DNA with a 
sonicator.  The sizes of the DNA decreased with increased sonication time.  
I can't exactly remember the time periods of sonication but it may have 
been in the seconds range.  Marianne L.  Univ. of South Florida, Biology, 
Tampa, FL.

On 15 Jun 1995, Maria Cristina Costanzo wrote:

> Dear Netters,
>     We are thinking about constructing a random shear library and have been
> experimenting with shearing total yeast genomic DNA.  Young et al. (PNAS
> 82:2583,1985) sheared DNA (0.35 mg/ml) to an average of 5 kb with 150
> passages
> through a 25-gauge needle. We started with DNA at about 0.15 mg/ml and
> after 350 passagess through a 25-gauge needle, it was largely unaffected,
> with the smallest fragments about 15 kb.  Does anyone have any suggestions
> about how to shear DNA efficiently ?  Does the concentration affect
> shearing efficiency ? Any suggestions would be appreciated.  You may
> contact me directly at mcc9 at cornell.edu, or post here; I will post a
> summary of the replies. Thank you!
>     Maria Costanzo 

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