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

[John E Simmons]

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> 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> on behalf of Shoobs,
> Nate <shoobs.1 at osu.edu>
> *Sent:* Wednesday, July 1, 2026 5:41 PM
> *To:* Natural History Collections Listserv <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
>
> --
> [image: 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
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