[Nhcoll-l] [EXTERNAL] Best practices for transferring specimens from RNAlater to ethanol + transferring specimens from -80 to room temp

[Shoobs, Nate]

Hey all,
Thanks for the replies. To clarify — The specimens are frozen at -80 currently in the collector’s lab. Once they get shipped here, I could keep them in at -80 or transfer to room temp storage. Or I could even transfer to ethanol and put back in -80.

My main desire is that the specimens remain stable morphologically  in perpetuity.

To John’s point RE preservation of larger specimens — The collector indicated that RNALater was not very effective in penetrating the tissues of the specimens (small terrestrial slugs) so the specimens were dissected in the field to increase penetration into different organ systems. And some have apparently degraded a bit while being stored in -80 in RNAlater.

So there are two questions — one is a procedural question which I think is answered: “how do I best transfer from RNAlater to 70% ETOH” answer: “soak in DI water and then step up through a graded ETOH series”.

But the other question is, is this the best practice / thing one should do if one has important vouchers like this that need to be kept in perpetuity.

The storage medium/space is not an issue (I have plenty of space in our -80) and in our room temp wet collection.
-Nate
-
Nathaniel F. Shoobs, Curator of Mollusks
College of Arts & Sciences Dept. of Evolution, Ecology, and Organismal Biology, The Ohio State University
Museum of Biological Diversity
1315 Kinnear Rd, Columbus, OH 43212
614-688-1342 (Office)
mbd.osu.edu<http://mbd.osu.edu/>
________________________________
From: John E Simmons <simmons.johne at gmail.com>
Sent: Wednesday, 01 July 2026 21:36:50
To: Kevin Kocot <kmkocot at ua.edu>
Cc: Shoobs, Nate <shoobs.1 at osu.edu>; Natural History Collections Listserv <nhcoll-l at mailman.yale.edu>
Subject: Re: [Nhcoll-l] [EXTERNAL] Best practices for transferring specimens from RNAlater to ethanol + transferring specimens from -80 to room temp

RNA later is marketed as a preservative for RNA and DNA and histological samples of 0. 5 cm or thinner, not for larger, whole specimens. It contains sodium citrate tribasic dehydrate (as a buffer) and ammonium sulfate (a protein precipitator),


RNA later is marketed as a preservative for RNA and DNA and histological samples of 0.5 cm or thinner, not for larger, whole specimens. It contains sodium citrate tribasic dehydrate (as a buffer) and ammonium sulfate (a protein precipitator), but as far as I have been able to determine, it does not contain any chemicals known to be successful long-term preservatives. The few published reports of it as a successful fixative or preservative are all based on relatively short time periods. Assuming the specimens are not frozen, I would transfer the specimens to deionized water (not distilled water or tap water), the step then up through 20% concentration stages to 70% ethyl alcohol.


--John

John E. Simmons
US Fulbright Senior Scholar
Writer and Museum Consultant, Museologica
and
Research Associate, Earth and Mineral Sciences Museum & Art Gallery, Penn State University
and
Investigador Asociado, Departamento de Ornitología, Museo de Historia Natural, Universidad Nacional Mayor de San Marcos, Lima


On Wed, Jul 1, 2026 at 7:48 PM Kevin Kocot <kmkocot at ua.edu<mailto:kmkocot at ua.edu>> wrote:
Hi Nate and all,

What temperature are the specimens currently at? If already frozen solid at -80, I would leave them as-is as they are stable. Otherwise, I would not directly transfer to ethanol but stepwise hydrate/rinse them and then dehydrate them in ethanol.

Best,
Kevin


________________________________
From: Nhcoll-l <nhcoll-l-bounces at mailman.yale.edu<mailto:nhcoll-l-bounces at mailman.yale.edu>> on behalf of Shoobs, Nate <shoobs.1 at osu.edu<mailto:shoobs.1 at osu.edu>>
Sent: Wednesday, July 1, 2026 5:41 PM
To: Natural History Collections Listserv <nhcoll-l at mailman.yale.edu<mailto:nhcoll-l at mailman.yale.edu>>
Subject: [EXTERNAL] [Nhcoll-l] Best practices for transferring specimens from RNAlater to ethanol + transferring specimens from -80 to room temp

Hey all,
I have some specimens coming in to our collection soon that have been preserved in RNAlater, but have  been successfully sequenced and are vouchers for a forthcoming publication.
The specimens will mainly serve as morphological vouchers now, as they have been sequenced to the extent that they likely ever will be (transcriptomes have been successfully sequenced).
The RNAlater seems like it might not be a good long-term storage solution for morphological vouchers.

Does any other collection have experience with:

  1.
transferring RNAlater specimens to ethanol (70%)
  2.
deciding whether to store a specimen at -80 long term, vs transitioning it to room temp storage

Best,
Nate

--
[The Ohio State University]
Nathaniel F. Shoobs
Curator of Mollusks
College of Arts & Sciences Dept. of Evolution, Ecology, and Organismal Biology
Museum of Biological Diversity, 1315 Kinnear Rd, Columbus, OH 43212
614-688-1342 (Office)
mbd.osu.edu/collections/invertebrates<https://mbd.osu.edu/collections/invertebrates>
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