DNA from formalin preserved specimens

David Johnstondaj daj at nhm.ic.ac.uk
Thu Jul 8 06:56:24 EST 1993


>On 7 Jul 93 20:08:18 GMT,
> <nichoki at ducvax.auburn.edu> writes:

>hey, I've got some animals that have been preserved in formalin and 
>stored in alcohol.  I wanted to isolate DNA from these animals, but
>it is extremely difficult to get clean, high molecular weight DNA from
>animals preserved in this manner.  Anybody have any ideas?

It must be possible..... (famous last words)

There are many reports of successful in situ hybridisation on formalin-
fixed, wax-embedded sections in the literature so the DNA must be in a 
reasonably useful state. It may be worth looking up some of these to see if 
they suggest any "wizzard wheezes".

We routinely extract DNA from alcohol preserved worms (albeit pretty damm 
small ones). We just soak them in several changes of TE over several days 
before standard proreinase K/phenol extraction (a la Manniatis). 
(presumably vacuum-drying would also remove the alcohol although we haven't 
tried it). Occasionally this method gives sheared DNA and in such cases we 
have found that the Nucleon DNA extraction kit from Scotlab works well 
(after soaking in TE).

I guess that, whatever you try, go for peripheral tissues as these would 
have been fixed first and so, less subject to autolysis. This statement 
may not apply to arthropods as I have once seen a dragonfly larva still 
crawling around after several days in formalin!!! 

Cheers, 

DAJ
David A. Johnston
Dept of Zoology, The Natural History Museum, Cromwell Road,
South Kensington, London SW7 5DB.
(tel 071 9389297, fax 071 9388754, email daj at nhm.ic.ac.uk)



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