Freezing damage DNA?

Zhonglin Chai zchai at COBRA.PATH.MONASH.EDU.AU
Fri Aug 25 03:15:53 EST 1995

> In article <416ffu$8ub at>
> "h.woo" <h.woo at> writes:
>| It seems that freezing and thawing repeatedly does affect DNA, as far as
>| using genomic DNA as PCR template is concerned. I keep my genomic DNA
>| stock solutions at 4C.
>I've heard the reasons why multiple freeze-thaw cycles of PCR primer stocks
>could limit the PCR, but I haven't heard anything about genomic DNA samples.
>How could this happen? Are the samples already restriction digested or just
>stored as genomic DNA isolates?

Multiple cycles of freeze-thaw of both PCR and sequencing primers in my
hands never affected results. For long DNA molecules, like genomic DNA and
lambda phage DNA (40 plus kd), I always keep them at 4 degrees C.,
considering that the -20 degree C. freezing and thawing cycles would create
ice crystals, that shear or break long DNA molecules (fibres) very easily.

ZhongLin Chai

Department of Pathology and Immunology
Monash Medical School
Alfred Hospital
Commercial Rd, Prahran, Victoria, AUSTRALIA
Telephone: (61 3) 276 2698
           (61 3) 388 1205 (home)
Fax:       (61 3) 529 6484
email:     zchai at

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