[NHCOLL-L:5142] RE: white crystals appearing on specimens in fluid, any i...
Dirk Neumann
Dirk.Neumann at zsm.mwn.de
Fri Dec 17 03:19:58 EST 2010
Hello Heather,
I have observed similar encrustations on fish specimens. It seems that
this is especially a problem of species with a fat rich diet (or fatty
specimens in general), e.g. in phytophagus Tilapias or in cyprinids.
Those incrustations, which might also grow on included labels or forms a
flocculent precipitation on the bottom of the lot, may be easily
removed when rinsing the specimen with hand warm/hot water. Changing the
preservative fluid and cleaning the container would be advisable.
Crystalline, paraformaldehyde encrustations are more difficult to
remove, as they (normally) appear (at least in fishes) within or
underneath of bony structures, e.g. within the lateral line canal or
below scales. Unlike cholesterol (Thanks for this hint, Simon &
Judith!), these crystals apparently destroy the bony structures and
removing is more difficult. I had some good results with placing such
specimens for some 10-15 min in hand warm water, adding little bit
detergent, and then carefully brushing the precipitation off with a
soft bottle brush. This has to be done very carefully and always into
the direction e.g of scales (never against!), as infected scales or
other bony structures tend to be very weak and can be damaged easily.
A possible reason for this paraformaldehyde crystals might be usage of
unbuffered formaldehyde solution for fixation - at least I recognised
this kind of problem quite frequently with specimens, which have been
preserved with formaldehyde obtained somewhere in an African pharmacy. A
second issue here might be inadequate production based on paraformalin
solution. Tentatively, this seems to be a problem again with more fatty
specimens/species, and I would not be surprised if shifts of the pH to
values below 7 caused by dissolved fatty acids from the specimens would
speed up this process. Before crystal manifestations on the specimens
starts to grow, you should be able to recognise a very fine
paraformaldehyde precipitation, either as needles or floating in the
fluid. If that occurs, changing of the alcohol and rinsing of specimens
with alcohol would be strongly recommended.
Hope this helps,
All the best
Dirk
Am 16.12.2010 23:47, schrieb Couteaufin at aol.com:
> Heather,
> I have observed this before on specimens prepared by Fric (Prague) et
> al. where little white waxy blobs form on the edge of the vials
> covered with netting - I presume that yours are similar.
> Chemically these should dissolve in alcohol but if the preservative
> contains enough aqueous-based reagents then the
> precipitation/coagulation is possible. Could well be cholesterol. I
> am still surprised however, that it forms on top of the tubes rather
> than the specimens themselves.
> Hope that this ramble is useful in some way.
> With all good wishes, Simon
>
> Simon Moore MIScT, FLS, ACR,
> Conservator of Natural Sciences,
> 20 Newbury Street,
> Whitchurch RG28 7DN.
> www.natural-history-conservation.com
> <http://www.natural-history-conservation.com/>
> www.pocket-fruit-knives.info <http://www.pocket-fruit-knives.info/>
>
> http://uk.linkedin.com/in/naturalsciencespecimenconserve
> In a message dated 16/12/2010 22:20:54 GMT Standard Time,
> JPRICE at mus-nature.ca writes:
>
> Heather
>
> I had similar stuff in a jar of tapeworms, although in this case
> it was white pearly flakes. I had our mineralogy guys run it under
> the x-ray chromatograph. They tell me it's cholesterol, likely
> dissolved out of the tissues and then precipitated.
>
> But dammit Jim, I'm a collection manager, not a chemist!
> Judith
>
> Judith C. Price
> Secretary, Society for the Preservation of Natural History Collections
> Assistant Collections Manager, Invertebrates / Gestionnaire
> adjointe des collections invertébrés
> Canadian Museum of Nature / Musée canadien de la Nature
> PO Box 3443 Station D / CP 3443 Succ <<D>>
> Ottawa, Ontario K1P 6P4 CANADA
> Tel.613.566.4263 / Fax.613.364.4027
> jprice at mus-nature.ca
> @nature_jcp
> www.nature.ca / www.spnhc.org
>
>
>
> -----Original Message-----
> From: owner-nhcoll-l at lists.yale.edu
> [mailto:owner-nhcoll-l at lists.yale.edu] On Behalf Of Heather Campbell
> Sent: Thursday, December 16, 2010 3:21 PM
> To: NHCOLL-L at lists.yale.edu
> Subject: [NHCOLL-L:5137] white crystals appearing on specimens in
> fluid, any ideas?
>
>
> Hello all,
>
> While rehousing the bee wet collection I have noticed that some vials
> contain specimens that have white material growing (?) on them.
> Here are
> a few details that may be important when considering a diagnosis:
> 1. Only vials containing larvae (maybe pupae) are affected
> 2. Different species and different years (but always older than
> 5yrs) and
> different locals
> 3. Preservative used: Kahle's sol
> acetic acid (glacial) 10%
> formalin (37%) 10%
> water 25%
> Ethanol (75%) 55%
> 4. Easily scraped away and has a plaque-like resemblance
> 5. no visible damage done to specimen (naked eye)
>
> I have pictures but am unable to send due to limits on message
> size. I
> will be happy to send these along to anyone who is interested.
>
> Thank you
>
> Heather M. Campbell
> Bee Curatorial Assistant
> Division of Invertebrate Zoology
> American Museum of Natural History
> Central Park West @ 79th st.
> New York, NY 10024-5192
> 212-496-3447
>
>
> Heather M. Campbell
> Bee Curatorial Assistant
> Division of Invertebrate Zoology
> American Museum of Natural History
> Central Park West @ 79th st.
> New York, NY 10024-5192
> 212-496-3447
>
--
Dirk Neumann
Tel: 089 / 8107-111
Fax: 089 / 8107-300
email: Dirk.Neumann(a)zsm.mwn.de
Postanschrift:
Staatliche Naturwissenschaftliche Sammlungen Bayerns
Zoologische Staatssammlung München
Dirk Neumann, Sektion Ichthyologie / DNA-Labor
Münchhausenstr. 21
81247 München
Besuchen Sie unsere Sammlung:
http://www.zsm.mwn.de/ich/
---------
Dirk Neumann
Tel: +49-89-8107-111
Fax: +49-89-8107-300
email: Dirk.Neumann(a)zsm.mwn.de
postal address:
Bavarian Natural History Collections
The Bavarian State Collection of Zoology
Dirk Neumann, Section Ichthyology / DNA-Lab
Muenchhausenstr. 21
81247 Munich (Germany)
Visit our section at:
http://www.zsm.mwn.de/ich/
-------------- next part --------------
An HTML attachment was scrubbed...
URL: http://mailman.yale.edu/mailman/private/nhcoll-l/attachments/20101217/cbb9b06c/attachment.html
More information about the Nhcoll-l
mailing list