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<DIV><FONT size=2 face=Arial>To rehydrate or not to.....</FONT></DIV>
<DIV><FONT size=2 face=Arial></FONT> </DIV>
<DIV><FONT size=2 face=Arial>Charlie Sturm has pointed out the main caveats and
I have always maintained that the decision whether to rehydrate or leave alone
is up to the individual, providing they fully understand the pros and
cons.</FONT></DIV>
<DIV><FONT size=2 face=Arial>In my experience I have rarely had anything
rehydrated that was not worth the effort but these were carefully selected and
then they were re-fixed in formalin as a precaution in case any of the
stabilising chemical changes brought about by the initial fixation, were undone
by the rehydration process; then the hydrated and re-fixed specimens were
transferred to a suitable preservative solution - usually 70-80% IMS. The
specimens always look rather brown if they were totally desiccated but look
quite fresh if they had not been desiccated for long (months rather than years).
</FONT></DIV>
<DIV><FONT size=2 face=Arial></FONT> </DIV>
<DIV>
<DIV><FONT size=2 face=Arial>As Dirk pointed out, if there are more specific
issues, then do feel free to ask.</FONT></DIV></DIV>
<DIV><FONT size=2 face=Arial></FONT> </DIV>
<DIV><FONT size=2 face=Arial>With all good wishes, Simon </FONT></DIV>
<DIV> </DIV>
<DIV><FONT size=2 face=Arial>Simon Moore MIScT, FLS, ACR<BR>Conservator of
Natural Sciences and Cutlery Historian,<BR><A
href="http://www.natural-history-conservation.com">www.natural-history-conservation.com</A>
<BR></FONT></DIV>
<BLOCKQUOTE
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<DIV style="FONT: 10pt arial">----- Original Message ----- </DIV>
<DIV
style="FONT: 10pt arial; BACKGROUND: #e4e4e4; font-color: black"><B>From:</B>
<A title=Dirk.Neumann@zsm.mwn.de href="mailto:Dirk.Neumann@zsm.mwn.de">Dirk
Neumann</A> </DIV>
<DIV style="FONT: 10pt arial"><B>To:</B> <A title=CSTURMJR@pitt.edu
href="mailto:CSTURMJR@pitt.edu">CSTURMJR@pitt.edu</A> </DIV>
<DIV style="FONT: 10pt arial"><B>Cc:</B> <A title=rebecca_cole-will@nps.gov
href="mailto:rebecca_cole-will@nps.gov">Cole-Will,Rebecca</A> ; <A
title=nhcoll-l@mailman.yale.edu href="mailto:nhcoll-l@mailman.yale.edu">NH
Coll</A> ; <A title=couteaufin@btinternet.com
href="mailto:couteaufin@btinternet.com">couteaufin@btinternet.com</A> </DIV>
<DIV style="FONT: 10pt arial"><B>Sent:</B> Friday, January 04, 2013 7:03
AM</DIV>
<DIV style="FONT: 10pt arial"><B>Subject:</B> Re: [Nhcoll-l] Is there a test
to determine what fluid specimens are preserved in -- formalin or
ethanol?</DIV>
<DIV><BR></DIV>
<DIV class=moz-cite-prefix>Dear Rebecca,<BR><BR>completely agree with Charlie.
As long as you don't have any climate control issues in your collection that
could trigger mould issues, I would leave the dry specimens in the jar as they
are. Especially in old historic specimens it is not always clear which type of
preservation fluids were used for initial preparation/fixation. There is a
whole variety of historic fixatives, some of them include heavy metal salts
such as mercury in rather high concentrations (these were often used e.g. for
preparations of marine invertebrates). If you don't know the history of
preservation/fixation methods in your collection, I would be very careful in
handling these specimens. Have in mind that prevailed usage of formaldehyde
fixation/preservation starts roughly around 1910. Dried ethanol specimens may
look rather poor (not initial fixation, only ethanol preservation = +/-
dehydration of specimens to a certain extent). Be careful if your specimens
have been prepared prior to 1900 and still look +/- good or show some salty
incrustations on the specimens, which could be an indicator for historic
fixatives other then formaldehyde.<BR><BR>Rehydration will not restore the
their original shape of specimens. If rehydration is necessary, I would also
recommend method Simon Moore suggested in a previous NHCOLL-L posting (see
below). For specific questions it might be worth contacting Simon
directly. <BR><BR><BR>All the best<BR>Dirk<BR><BR>*************<BR><FONT
id=role_document color=#000000 size=2 face=Arial><FONT lang=0 size=2
face=Arial ptsize="10" family="SANSSERIF">From: Simon Morre, <A
class=moz-txt-link-abbreviated
href="mailto:couteaufin@btinternet.com">couteaufin@btinternet.com</A></FONT></FONT><BR><FONT
id=role_document color=#000000 size=2 face=Arial><FONT lang=0 size=2
face=Arial ptsize="10" family="SANSSERIF">Sent: 21/08/2011 12:00:02 GMT
Daylight Time<BR>Subj: Re: [NHCOLL-L:5600] FW: Rehydration of a sea
anemone</FONT></FONT><BR><BR><FONT lang=0 size=2 face=Arial ptsize="10"
family="SANSSERIF"><FONT style="BACKGROUND-COLOR: transparent" color=#000000
size=2 face=Arial><FONT color=#000000 size=2 face=Arial>
<DIV>Always rather ticklish when you have the holotype to perform such a
radical treatment!</DIV>
<DIV>Bear in mind also that rehydration will improve the appearance and
texture but it will compromise future DNA extraction/readings. If you
need further advice on this let me know.</DIV>
<DIV>I have also forwarded this to John Simmons who may also have some
comments.</DIV>
<DIV> </DIV>
<DIV>I tend to use Decon-90 at around 3 to 5% in deionised water as a
rehydrating agent.</DIV>
<DIV>The reaction is catalysed by warming it to no more than 50 deg.
Centigrade (hotplate) and make sure that the container has a loose lid to
prevent massive evaporation during warming.</DIV>
<DIV>Obviously photograph and weigh the specimen prior to treatment.</DIV>
<DIV>Start the process first thing as it can take some time and so that you
can monitor its progress during the day. </DIV>
<DIV>The fluid will start to yellow a bit and may smell rather fishy; the
specimen will gradually sink into the fluid - this will only happen in an
ideal situation, so if the specimen has expanded and feels soft and more
flexible like it should if not dry, then it will have reached its
'end-point'. If it's still floating then it will have air trapped
inside.</DIV>
<DIV> </DIV>
<DIV>In which case.... place the specimen in clean water and place the
container inside a vacuum desiccator. Apply a mild vacuum to it and air
should bubble out of the specimen. After no more than a minute, stop the
pump (making sure that the hose is removed from the desiccator and that the
tap is closed <STRONG>before</STRONG> the pump is switched off - or it will
suck the oil from the pump all over the specimen!!)</DIV>
<DIV>Then release the vacuum slowly and the anemone should sink completely or
partly. Repeat the process until no more air bubbles out. Small
amounts of trapped air will often slowly diffuse out later in the alcohol
preservative (see below).</DIV>
<DIV>You should now have a fully rehydrated specimen. Place into
formalin to refix overnight and next day start to transfer into an alcohol
dehydration ladder so that by the end of the day, the specimen is preserved in
IMS once again. Ensure that the jar seal is good! Finally, make a
note of the treament for the specimen's record and reweigh the specimen,
having drained off excess fluid and re-photo.</DIV>
<DIV> </DIV>
<DIV>That should hopefully be it!</DIV>
<DIV> </DIV>
<DIV><FONT lang=0 size=2 face=Arial ptsize="10" family="SANSSERIF">With all
good wishes, Simon<BR><BR>Simon Moore MIScT, FLS, ACR,<BR>Conservator of
Natural Sciences,</FONT></DIV></FONT></FONT></FONT><BR><BR><BR>Am 04.01.2013
05:34, schrieb <A class=moz-txt-link-abbreviated
href="mailto:CSTURMJR@pitt.edu">CSTURMJR@pitt.edu</A>:<BR></DIV>
<BLOCKQUOTE
cite=mid:f3022b57df9f0ee79fe701819371fd6a.squirrel@webmail.pitt.edu
type="cite"><PRE wrap="">Rebecca,
I will not opine on how to test what solution may have been used to store
the specimens, however, I will question why you might want to rehydrate
them. Unless there is a specific need to rehydrate a specimen, I would
advocate to leave them in a dessicated state. The specimen is already
dessicated and as such will probably stay that way for a long time (unless
something is done to it). Rehydration methods can adversely affect a
specimen. Better methods may be available in the future. Unless there is a
need to rehydrate the specimen for a current study, store it dry. I have
attached a chapter that I wrote six years ago and there are some
references in Section 5.9 that you might like to read before rehydrating.
</PRE>
<BLOCKQUOTE type="cite"><PRE wrap="">Hello all,
We have several old collections in the park without any information about
how they were prepared. Many need to be rehydrated and rehoused into
better storage. Is there a simple test to determine what they are/were
preserved in before we rehydrate?
thank you
--
Rebecca Cole-Will, Cultural Resources Program Manager ~ Acadia National
Park, 20 McFarland Hill Drive, PO Box 177, Bar Harbor, ME 04609
~207.288.8728 ph., 207.288.8709 fx.
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</PRE></BLOCKQUOTE><PRE wrap="">
Regards,
Charlie
.................................................
Charlie Sturm
Treasurer
American Malacological Society
Research Associate - Section of Mollusks
Carnegie Museum of Natural History
Pittsburgh, PA, USA
Associate Professor - Family Medicine
Fellow-American Academy of Family Practice
Fellow-Academy of Wilderness Medicine</PRE><BR>
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</PRE></BLOCKQUOTE><BR><BR><PRE class=moz-signature cols="72">--
Dirk Neumann
Tel: 089 / 8107-111
Fax: 089 / 8107-300
email: Dirk.Neumann(a)zsm.mwn.de
Postanschrift:
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81247 München
Besuchen Sie unsere Sammlung:
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---------
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:
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