RE: nuclc acid fix (TCA+); also Barbi
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From: | "Kellar, Eric" <kellarec@MSX.UPMC.EDU> |
To: | Histonet <histonet@pathology.swmed.edu>, "'J. A. Kiernan'" <jkiernan@julian.uwo.ca> |
Reply-To: | |
Content-Type: | text/plain |
Would that clever chemist happen to have been Johann Friedrich Wilhelm Adolf
von Baeyer?
> ----------
> From: J. A. Kiernan[SMTP:jkiernan@julian.uwo.ca]
> Sent: Tuesday, May 16, 2000 1:35 AM
> To: Histonet
> Subject: Re: nuclc acid fix (TCA+); also Barbi
>
> A lot of questions ---> A long answer.
> Delete now if you aren't interested.
>
> On Mon, 15 May 2000, Mike King wrote:
> > > non-formaldehyde fixatives for better preservation of DNA and RNA
> > and John Kiernan replied:
> > ...In traditional histochemistry the best fixatives for DNA and RNA...
> > Are you ... aware of any attempts to incorporate into fixatives
> reagents
> > such as trichloracetic acid, used to precipitate DNA in biochemical
> > preparations? Or RNAse inhibitors?
>
> Reply:
>
> RNase inhibitors: Diethylpyrocarbonate has been used, but (I think)
> for the wrong reasons. I'll check and report if anything turns up.
>
> Trichloroacetic acid (TCA) is a coagulant fixative of proteins.
> According to M. Gabe's big book "Histological Techniques" (1975)
> it preserves much more delicate structure than one would expect
> when used alone. In real practice TCA is used only as a component
> of Heidenhain's SUSA. This is one of the best fixatives for light
> microscopy, but is currently _fixator_non_grata_ on account of
> its containing mercuric chloride and other poisonous chemicals,
> including TCA. The TCA in SUSA may help in precipitating DNA, but
> the mixture also contains enough acetic acid to do this quite
> adequately. Much higher concentrations of TCA _extract_ nucleic
> acids from fixed tissues. TCA and also perchloric acid are still
> used histochemically for this purpose, as are DNase and RNase.
>
> Please be aware that it's not "Susa's fixative." A Susa did not
> invent it, and neither did Heidenhain name this excellent fixative
> after his favourite bird. SUSA is an acronym for Sublimat-Saure
> (with a few umlauts that can't be sent by email), which roughly
> translates to mercuric chloride with acids. Barbituric acid,
> barbiturates and all the other "barbi-" compounds commemorate
> "a lady named Barbara" revered and perpetuated by a particularly
> perspicacious chemist of the 1890s who recognized an unconventional
> "acid" structure. Can anyone remember the clever chemist's name?
>
> Eponyms are fun.
>
> John A. Kiernan,
> Department of Anatomy & Cell Biology,
> The University of Western Ontario,
> LONDON, Canada N6A 5C1
>
>
>
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