RE: [Histonet] Feulgen stain for DNA

From:"Smith, Allen"

Bouin's certainly does attack nucleotides, often making the Feulgen reaction
impossible (although sometimes one can get a Feulgen reaction on Bouin-fixed
tissue by just plopping it into Schiff's reagent).  I think it is the picric
acid, pK 0.4, rather than the acetic acid, pK 4.8, that hydrolyzes the
nucleotides.  Carnoy's fluid, with twice the acetic acid concentration of
Bouin's, is a good fixative for the Feulgen reaction.

Allen A. Smith, Ph.D.
Professor of Anatomy
Barry University
School of Graduate Medical Sciences
            Podiatric Medicine and Surgery
Miami Shores, Florida

-----Original Message-----
[] On Behalf Of Gayle Callis
Sent: Wednesday, May 12, 2004 12:45 PM
Subject: [Histonet] Feulgen stain for DNA

For Feulgens, Bouins may not be the best fixative particularly if you fix a
long time in this solution.  Acetic acid in Bouins the acetic acid in
Bouins starts hydrolyzing the purine and pyrimidine bases from sugar
phosphate groups to release aldhyde groups from the DNA deoxypentose sugar.
 This is the very reason acid decalcifiers are not recommended if one wants
to do Feulgens.  

When you then do Feulgens, HCL continues this hydrolyzation, the problem
lies in overhydrolyzation, and poor staining.  

Formalin may be a better fixation.    
Gayle Callis
Research Histopathology Supervisor
Veterinary Molecular Biology 
Montana State University - Bozeman
PO Box 173610
Bozeman MT 59717-3610
406 994-6367 (lab with voice mail)
406 994-4303 (FAX)

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