[NHCOLL-L:4114] RE: Possible replacement to alcohol storage?

[John E Simmons]

Opinions vary widely about the suitability of various fluids for preserving
tissues for DNA, which is not surprising given the number of variables that
can affect DNA quality (e.g., length of time between cell death and
sampling, cleanliness of the operation, whether the tissue sample was
exposed to UV in the field, storage temperature, type of plastic used for
the sample tubes, the technique used to extract DNA).

I believe that we can say that the best method for long-term storage of
tissues for DNA is freezing at -80C, and of the various solutions proposed
for holding tissues without freezing, 95% ETOH is best.

Although there have been a lot of publications about one buffer or mixture
or another, we don't yet have comparative long-term data to say much more
than that.  Many people who favor a particular buffer or fluid have based
their opinion on incomplete data--they usually don't know much about how the
samples were collected and stored, so it is difficult to make comparisons.

Personally, I would avoid (if at all possible) glycols and phenoxytols which
are really little more than detergents, and use a good preservative--or DNA
this means a quick dehydration method (freezing or alcohol), keep the
sampling equipment as clean as possible, and protect the tissues from heat
and ultraviolet radiation.

--John


On Mon, Dec 8, 2008 at 6:16 PM, Furth, David <FURTHD at si.edu> wrote:

>  All good points.
>
>
>
> Relative to point number 2, there have been some publications about the use
> and effectiveness of propylene glycol to preserve DNA.  Also our
> Invertebrate Zoology has been using Propylene Phenoxytol or a similar
> "sorting solution", especially for smaller-bodied specimens with
> exoskeletons (e.g., plankton) otherwise stored in formalin.  However, I am
> not certain about the length of time this has been used successfully.
>
>
>
> ******************************************************
>
> David G. Furth, Ph.D.
>
> Department of Entomology
>
> MRC 165, P.O. Box 37012
>
> National Museum of Natural History
>
> Smithsonian Institution
>
> Washington, D. C. 20013-7012  USA
>
> Phone: 202-633-0990
>
> Fax: 202-786-2894
>
> Email: furthd at si.edu
>
> Website: www.entomology.si.edu
>   ------------------------------
>
> *From:* owner-nhcoll-l at lists.yale.edu [mailto:
> owner-nhcoll-l at lists.yale.edu] *On Behalf Of *John E Simmons
> *Sent:* Saturday, November 29, 2008 9:30 PM
> *To:* JBRYANT at riversideca.gov
> *Cc:* Makos, Kathryn; NHCOLL-L at lists.yale.edu
> *Subject:* [NHCOLL-L:4099] RE: Possible replacement to alcohol storage?
>
>
>
> This is a very interesting discussion, and I am pleased to see the level of
> interest in the topic. I would like to add a few points:
>
> 1.  Museums lack proper studies of what happens to containers of 70%
> ethanol or "10% formalin" during a fire.  Data exists for storage of retail
> liquor (which averages less than 15% alcohol) and bulk storage of 95%
> alcohol in large drums, but museum collections and specimens on exhibit fall
> in between.  The cost of such studies is very high--it would be great if
> Factory Mutual or some outfit like that would take up the cause.  We know
> that ethanol is flammable, but we also know that ethanol fumes disperse very
> quickly from an opened container or a spill, greatly reducing the fire
> hazard.  We really don't know how much of a danger the specimens pose, but
> we do know it is far less than 95% alcohol (the rules for 95% alcohol are
> frequently applied to museum collections).  In their defense, we must
> remember that the regulatory agencies have to make a guess by extrapolating
> from existing regulations, which usually leaves all parties unhappy.
>
> 2.  We need to keep in mind the difference between a preservative (a
> chemical that prevents deterioration from occurring, such as alcohol or
> formaldehyde) and a "holding solution" that might be used in the short term
> while a fluid preserved specimen is on exhibit or used in a classroom (e.g.,
> Novec, or the available proprietary fluids such as Wardsafe or Carosafe that
> contain glycols, phenols, and other compounds).  The "holding solutions"
> don't preserve specimens long-term and may be very harmful to the specimen.
>
> 3.  The literature on fluid preservation is full of recommendations of
> oddball concoctions that various individuals have claimed are good
> preservatives, but most of them are not.  To avoid adding even more
> anecdotal recipes to the mix, museums should follow the lead of the
> Smithsonian and collect all the data they can from experiments with new
> fluids.
>
> --John
>
> John E. Simmons
> Museologica
> 128 E. Burnside Street
> Bellefonte, Pennsylvania 16823-2010
> simmons.johne at gmail.com
> 303-681-5708
> and
> Adjunct Curator of Collections
> Earth and Mineral Science Museum & Art Gallery
> Penn State University
> 19 Deike Building
> University Park, Pennsylvania 16802-2709
> jes67 at psu.edu
>



-- 
John E. Simmons
Museologica
128 E. Burnside Street
Bellefonte, Pennsylvania 16823-2010
simmons.johne at gmail.com
303-681-5708
www.museologica.com
and
Adjunct Curator of Collections
Earth and Mineral Science Museum & Art Gallery
Penn State University
19 Deike Building
University Park, Pennsylvania 16802-2709
jes67 at psu.edu
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