[NHCOLL-L:3803] Re: [Annelida] formol vs RCL2

[Andries J. van Dam]

Dear All,

My first thoughts about RCL2, a possible substitute for formol that seems to
be successfully applied in medical histopathology.
It seems that looking at the patent that RCL2 is 70% EtOH with the addition
of acetic acid (likely added for better/stronger fixation) and trehalose, a
disaccharide that is part of plants and involved in the protection against
dehydration. 
The interesting thing about this fixative/preservative is that the acidic
alcohol its dehydration properties are possibly neutralized by the trehalose
which apparently makes the alcohol mixture not only usable for
preserving/analysing DNA and (functional) proteins but also provide good
morphology, which is a problem with plain ethanol 75% (shrinkage and cell
collapse).
I am curious about the pH and its stability. Also has to be remarked that it
is like ethanol still a hazardous compound with regard to flammability.
Other alternatives for formalin might be found in DMDM-hydantoin a safe
alternative for formalin used primarily in shampoos and hand soaps.

More info about DMDMH:

van Dam, Andries J. 2003. DMDM-Hydantoin: The promising Result of a Search
for an Alternative in Fluid Preservation of Biological Specimens. Collection
Forum, 18(1-2):104-115.

Molin, Daniël G.M. and Andries J. Van Dam. 2006. A Preservation Method
Supporting Multipurpose Analysis of Long-stored Samples. Cell Preservation
Technology. March 1, 2006, 4(1): 46-50.

 --
Andries J. van Dam, conservator

Co-ordinator ICOM-CC Working Group Natural History Collections
http://icom-cc.org/WG/NaturalHistoryCollections

Administrator WG-interactions, the official forum site of ICOM-CC:
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From: annelida-bounces at oat.bio.indiana.edu on behalf of Geoff Read
Sent: Wed 3/19/2008 10:01 PM
To: annelida mailing list
Subject: Re: [Annelida] formol vs RCL2

>>> On 20/03/2008 at 4:27 a.m., Stanislas DUBOIS <Stanislas.Dubois at ifremer.fr>
> For safety and health reasons, formaldehyde (formol) will be soon
> prohibited (at least in Europe .. I'm not sure for other countries).
> That might be problematic for specimen preservation since, as many of
> you I guess, I used to fix collected polychaetes from benthic samples in
> formaldehyde.  I just learned that RCL2 might be of great interest to
> substitute for formol.  Does anyone already experience this surrogate
> formol or does anyone has any information to share with me, as far as
> fixation quality of tissues for IDs (I'm not talking of doing any
> molecular analysis), preservation of pigments etc....

Thanks for the news Stan. My guess is that RCL2 has yet to spread far in the
medical world, and even less into general use.
The formulation is not public but contains acetic acid (vinegar). Perhaps
someone can find out how much more expensive it is compared to formalin,
bearing in mind that it's the medical/pathology market that they're selling
it into.

Those interested can check the company web page:
http://www.alphelys.com/site/us/pFF_FixateurSansFormol.htm

The paper of 2006 by Delfour et al that they cite,  is available full text
at pubmed

"RCL2, a New Fixative, Preserves Morphology and Nucleic Acid Integrity in
Paraffin-Embedded Breast Carcinoma and Microdissected Breast Tumor Cells"

http://www.pubmedcentral.nih.gov/

just search for rcl2.

Yes, there is a general understandable reluctance of field workers to use
formalin these days. I dislike working with it also. But, I find the usual
substitute - ethanol - can result in rigid brittle specimens that are very
inferior to those formalin-fixed for morphology and identification, or in
disintegrating rubbish in bulk, sediment-laden samples.

Geoff






--

 Geoff Read <g.read at niwa.co.nz>
   http://www.annelida.net/
  http://www.niwascience.co.nz/ncabb/



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