Thanks a lot Louise Renton for understanding my question with so
few clues.

Tissues come from an anencephal fetus that has been in formol for at
least 30 years. We do the DNA extraction for a PCR

I thought in washing the tissue before starting with qiagen protocol
but also thought it would be a good idea to ask it to somebody with more
experience.

I don't know exactly why  we are having quite good results with
parafin sections and not the same with only fixed tissue....may be
because in parafin sections formalin rests have disappeared after
washing with water and diferent changes in alcohol?...I really don't
know, it's sure that somebody better than me in this field
can solve the doubt.




From:          "louise renton" 
To:            TEC-LAB-DEP01@med.ub.es, histonet@pathology.swmed.edu
Subject:       DNA extraction
Date:          Tue, 23 Jul 2002 07:33:03 +0000

Dolores,

If the tissue is not embedded, but straight out of the fixative, wash the
chopped up sample  for a couple of hours in several changes of sterile water
and then proceed as usual to the digestion step (spin down before each
change to remove as much of the water as possible).
Extraction of DNA  for PCR from long stored formalin fixed, paraffin wax
embedded tissues can be a problem, as the DNA becomes degraded over time, 
(I tried to get PCRable DNA from blocks embedded  in 1942, with no joy) and
standard phenol/coloform extraction (ref Maniatis) might be better and give
larger yield than the Quigen kit.

Hope this helps
Louise Renton


>From: Dolors Fuster 
>To: histonet@pathology.swmed.edu
>Subject: DNA
>Date: Mon, 22 Jul 2002 20:26:41 +0100
>
>Hi histonetters !
>
>What do you recommend us to obtain the best results in DNA extraction
>from formalin fixed tissue? should we do any kind of treatment before
>starting the
>extraction? (Water rinses, alcohol changes....)
>
>We are usin Qiagen kit with good results for parafin embeded samples
>fresh tissue and other kind of samples (cell culture, serum...). but
>are not successful with formalin fixed tissue
>
>Thanks in advance
>Dolors Fuster
>
>Tecnic Especialista en
>Anatomia Patologica
>Departament d'Anatomia i Embriologia Humana
>Facultat de Medicina (HCP)
>Universitat de Barcelona
>ICQ 14146798
>
>http://www.fashionmas.com/click/




Louise Renton
Bone Research Unit
MRC
Johannesburg
South Africa
Tel & fax +27 11 717 2298
"Time flies like an arrow, friut flies like a banana"
ex

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Dolors Fuster

Tècnic Especialista en
Anatomia Patològica
Departament d'Anatomia i Embriologia Humana
Facultat de Medicina (HCP)
Universitat de Barcelona
ICQ 14146798

http://www.fashionmas.com/click/