[Nhcoll-l] cleared and stained amphibians
a.j.van_dam at lumc.nl
a.j.van_dam at lumc.nl
Fri Oct 7 04:41:20 EDT 2022
Dear all,
If you want to clear tissue, you'll need a preservative with a relatively high refractive index (around 1.5) like glycerol, turpentine, benzyl benzoate and methyl salicylate (wintergreen oil). Ethanol alone won't work, although in combination with glycerol you might reach some translucency of the tissue, which might be sufficient for clearing amphibians.
With regard to glycerol and mould. When using glycerol above 65% in a well-sealed container the RH above the fluid will be lower than 70% which inhibits fungal growth. However, if the container in not tightly closed and the RH in your storage facility cannot be held below 70%, fungal growth can certainly occur! In such case, it might be wise to add a mould inhibitor like thymol. In other words, the choice to add a mould inhibitor greatly depends on the climate conditions in your facility and the quality of the container (preferably oxygen- and water-tight, since moulds need both enough oxygen and water to survive and thrive).
Hope this better explains why there are different advices given about this issue.
Kind regards,
Dries
Curator/conservator
Anatomical Museum - Leiden University Medical Centre
From: Nhcoll-l <nhcoll-l-bounces at mailman.yale.edu> On Behalf Of Sergio Montagud
Sent: donderdag 6 oktober 2022 18:35
To: NHCOLL-new <nhcoll-l at mailman.yale.edu>
Subject: [MOGELIJK SPAM ! *****] Re: [Nhcoll-l] cleared and stained amphibians
What improvement do you find in the glycerine that no have the ethanol 70? Unless the flammable condition (perhaps the main reason), ethanol 70 is an universal preservative, without toxic effects and no need added second compounds (mentol or timol).
Is best for herps?
Sergio
De: Nhcoll-l <nhcoll-l-bounces at mailman.yale.edu<mailto:nhcoll-l-bounces at mailman.yale.edu>> en nombre de Simon Moore <couteaufin at btinternet.com<mailto:couteaufin at btinternet.com>>
Fecha: jueves, 6 de octubre de 2022, 10:42
Para: Fabian Neisskenwirth <info at naturhistorische-konservierung.de<mailto:info at naturhistorische-konservierung.de>>
CC: NHCOLL-new <nhcoll-l at mailman.yale.edu<mailto:nhcoll-l at mailman.yale.edu>>
Asunto: Re: [Nhcoll-l] cleared and stained amphibians
Hi Tonya,
I have not added alcohol to alizarine transparencies before but use glycerine at 70% (diluted with deionised or RO water) and add a crystal of menthol rather than thymol (I don't care for the odour of the latter!) as a fungus preventer as it certainly does grow in glycerine solutions, even at 60%*, given the chance (alcohol would discourage fungus though). The menthol forms a very thin film over the surface of the fluid and prevents fungal spored from' germinating'.
* This was from a specimen prepared by an intern and then forgotten after she'd finished. I found the specimen about 3 months later and there was a healthy growth of mould on the fluid surface and the specimen's skin was being 'burned' by the fungal enzymes and producing irreversible black spots. I changed the fluid for 70% glycerol and added a crystal of menthol and no more problems since.
With all good wishes, Simon
Simon Moore MIScT, RSci, FLS, ACR
Conservator of Natural Sciences and Cutlery Historian,
www.natural-history-conservation.com<http://www.natural-history-conservation.com>
[cid:image002.png at 01D8DA30.E3503700][cid:image003.jpg at 01D8DA30.E3503700]
On 6 Oct 2022, at 07:48, Fabian Neisskenwirth <info at naturhistorische-konservierung.de<mailto:info at naturhistorische-konservierung.de>> wrote:
Hey Tonya,
I would recommend to measure the density of the solution before assuming anything. With this you can calculate what percentage of strength you can expect. Usually this can vary very much from literature, to literature. And i really have never heard the use of ethanol in clearings. The ones I have made are all in plain glycerol and water and are preserved very well.
And I would not add any thymol, since if the solution is above 65% mold growth is inhibited. Why use poison if not needed...
All the best,
Am 06.10.22 um 04:32 schrieb Bentley, Andrew Charles:
Tonya
We have sometimes mixed different proportions of glycerin and 70% ethanol to make the liquid less viscous and thus reduce bubble formation in cavities of C&S specimens but otherwise use full strength glycerin for these specimens with a couple of crystals of thymol added to prevent mold growth. The addition of 70% ethanol, as long as not too much, does not seem to affect these specimens in any adverse way - that we can tell.
Andy
A : A : A :
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V V V
Andy Bentley
Ichthyology Collection Manager
University of Kansas
Biodiversity Institute
Dyche Hall
1345 Jayhawk Boulevard
Lawrence, KS, 66045-7561
USA
Tel: (785) 864-3863
Fax: (785) 864-5335
Email: abentley at ku.edu<mailto:abentley at ku.edu>
ORCID: https://orcid.org/0000-0002-3093-1258
http://ichthyology.biodiversity.ku.edu
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From: Nhcoll-l <nhcoll-l-bounces at mailman.yale.edu<mailto:nhcoll-l-bounces at mailman.yale.edu>> on behalf of "Haff, Tonya (NCMI, Crace)" <Tonya.Haff at csiro.au<mailto:Tonya.Haff at csiro.au>>
Date: Wednesday, October 5, 2022 at 6:13 PM
To: "nhcoll-l at mailman.yale.edu<mailto:nhcoll-l at mailman.yale.edu>" <nhcoll-l at mailman.yale.edu<mailto:nhcoll-l at mailman.yale.edu>>
Subject: [Nhcoll-l] cleared and stained amphibians
Hello all,
We have some cleared and stained small frogs that are, I suspect, stored in a mixture of glycerine and ethanol. I have read in John's Fluid Preservation book that some people use a mixture the two at a 1:1 ratio (but at what ETOH concentration I am not sure), but I wonder if any of you would share how you store similar specimens? Some of the jars need to be topped up, so I also wonder if it's best to top up using a 1:1 ratio of glycerine to ethanol (given that's what it *looks* like, ha ha), or remove all fluid and replace, or...? Thoughts, as usual, appreciated!
Cheers,
Tonya
-------------------------------------------------
Dr. Tonya M. Haff
Collection Manager
Australian National Wildlife Collection
CSIRO
+61(0)419569109
https://www.csiro.au/en/about/facilities-collections/collections/anwc
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