Hi Gayle,
You are generally correct.
Essentially, the only proteins denatured (fixed) by acetic acid are the
nucleoproteins.
However, 5% aqueous acetic acid has been used as a fixative for chromosomes
in fresh material (commonly plant).
We used this in school to see mitosis in onion root tip, how's that for a
six decade old memory?
I have also used this more recently (only four decades back) to fix cell
cultures prior to staining for karyotype analysis.
Today most labs use acetic/methanol for this purpose.
The methods that I am familiar with, use either aceto-carmine or
aceto-orcein as a combination fixative/stain for chromatin.
I am sure that John K. can also come up with a version for Nissl substance.
All the best for the season.
Cheers,
Bryan
----- Original Message -----
From: "gayle callis" <gayle.cal...@bresnan.net>
To: "Histonet" <histonet@lists.utsouthwestern.edu>
Sent: Saturday, December 12, 2009 3:54 PM
Subject: [Histonet] Using acetic acid alone as a fixative
Dear Histonetters,
I have a person using acetic acid as a fixative for frozen sections
containing bioluminescent proteins (GFP and tdTomato, a red fluorescent
protein).
I have always been taught to use acetic acid in combination with other
chemical agents (e.g. as in Bouins or Carnoys) but not alone due to the
swelling of cells and tissues and probably other acid protein hydrolysis
going on too.
Has anyone ever run across using acetic acid (concentration is not high,
but
not known by me)? She does encounter problems with GFP staining, but the
tdTomato still glows although her results are inconsistent.
I have no clue where this fixation method originated from but I suspect it
may be from a fixative where something was lost in making it
up/forgotten/left out - ending up with acetic acid alone. A quick look in
Sheehan and Hrapchak's Theory and Practice of HIstotechnology, indicated
acetic acid was rarely used alone for fixation. I am off to John
Kiernan's
book after sending this message.
I understand the sensitivity of GFP and some other GFP chimeras , also RFP
(closely related structurally to GFP) to alcohols and other organic
solvents, heat, and pH where fluorescence is lost and/or diminished
significantly.
Enlighten me please
Gayle M. Callis
HTL/HT/MT(ASCP)
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