<html>
<head>
<meta content="text/html; charset=ISO-8859-1"
http-equiv="Content-Type">
</head>
<body text="#000000" bgcolor="#FFFFFF">
<div class="moz-cite-prefix">Dear Sonia,<br>
<br>
dehydration is not a caveat if you aim to preserve tissues for
later / future DNA analysis - this is what you aim for, as
residual water degrades the DNA helix. The long term preservation
of DNA not only depends on the ethanol you use (for tissues
storage use only undenatured pure ethanol and avoid technically
dried alcohols above 96% for this purpose), but also on general
storage settings. Tissues should be stored frozen, at least at
-25°C, better would be -80°C, best option surely is liquid
nitrogen - which is not feasible in many institutions /
collections for various reasons however.<br>
<br>
Dehydration and osmolarity surely is an issue for the preservation
of the soft tissues and lead to cell rupture, which should be
avoided in any case.<br>
<br>
If your collections aims in both directions, keeping tissues fit
for DNA analysis and voucher specimens for morphological
comparison, I would advise indivdualised tissue subsamples in pure
ethanol at -25/-80°C.<br>
<br>
For normal collection storage, the ethanol concentration should
not drop below 50%, as the water supports tissue degradation,
especially in marine invertebrates. Specific marine invertebrates
such as bryozoans might require special attention towards fixation
/ preservation of tissues, but I am not an expert in these groups.
However, keep in mind that if you use highly concentrated
denatured / undenatured ethanol for specimen storage, that you
might trigger pH issues for long term storage, as carbonates might
be dissolved out of the coral skeleton but pure ethanol has nearly
zero buffering capacity. This might not be that much of an issue
with coral specimens, but with other soft tissued invertebrates in
your collection that receive the same treatment.<br>
<br>
All the best<br>
Dirk<br>
<br>
<br>
<br>
<br>
Am 29.07.2014 10:31, schrieb Sonia Rowley:<br>
</div>
<blockquote
cite="mid:CANhU7LjDY1xujHhCc0+5x-XeNo+=KVG5LMs9x5W9BQhENsrBCg@mail.gmail.com"
type="cite">
<div dir="ltr">Dear List
<div><br>
</div>
<div>I am writing with regards any experience and evidence for
and against the use of 95% or ~70% EtOH for longterm
invertebrate (specifically gorgonian coral) specimen
preservation for collections. More and more institutions seem
to be turning to 95% EtOH, however, there are numerous
conflicting thoughts and evidence with regards the use of
higher concentrations for longterm specimen storage.
Furthermore, I understand that there are 2 types of high EtOH
concentration; clean and dirty with the latter being far
cheaper but unsuitable for genetic analyses. </div>
<div><br>
</div>
<div>Whilst collections are indeed a taxonomic concern, this
does include the use of molecular work as part of the suite of
tools in determining species differences. The collections I
have worked in using ~95% EtOH have had good success with both
storage and genetic work, but these specimens may often be a
maximum of 1 - 2 decades old. Conversely, others mention
caveats such as the high concentration dehydrating the
specimen to such an extent that it disrupts the integrity of
both specimen and DNA. At the same time the often high water
content of specimens is said to bring down the EtOH
concentration which may also cause issues with specimen
degradation. </div>
<div>
<div><br>
</div>
<div>Please excuse the somewhat rudimentary nature of my
question, there does seem a tremendous amount of confliction
in what is recommend and therefore it would be really
valuable to hear what people have to say and recommend from
the list. </div>
<div><br>
</div>
<div>Thank you for your time with this matter and look forward
to hearing any responses </div>
<div><br>
</div>
<div>Sonia</div>
<div><br>
</div>
-- <br>
<div dir="ltr">Sonia J. Rowley PhD<br>
<div>Research Affiliate</div>
<div>Bernice Pauahi Bishop Museum</div>
<div><span style="line-height:16px;border-collapse:separate">1525
Bernice St, </span><span
style="line-height:16px;border-collapse:separate">Honolulu, </span></div>
<div><span style="line-height:16px;border-collapse:separate">HI
96817,</span><span
style="border-collapse:separate;line-height:12px"><font
color="#e8e8e8" face="franklin-gothic-urw">,</font></span>USA</div>
<div>+1 808 348 6224<br>
</div>
<div><br>
</div>
<div>Research Affiliate<br>
University of Hawai'i at Manoa<span><br>
<font>2538 McCarthy Mall, Edmondson 312</font></span><font> </font>
<div>Honolulu, HI 96822</div>
</div>
</div>
</div>
</div>
<br>
<fieldset class="mimeAttachmentHeader"></fieldset>
<br>
<pre wrap="">_______________________________________________
Nhcoll-l mailing list
<a class="moz-txt-link-abbreviated" href="mailto:Nhcoll-l@mailman.yale.edu">Nhcoll-l@mailman.yale.edu</a>
<a class="moz-txt-link-freetext" href="http://mailman.yale.edu/mailman/listinfo/nhcoll-l">http://mailman.yale.edu/mailman/listinfo/nhcoll-l</a>
_______________________________________________
NHCOLL-L is brought to you by the Society for the Preservation of
Natural History Collections (SPNHC), an international society whose
mission is to improve the preservation, conservation and management of
natural history collections to ensure their continuing value to
society. See <a class="moz-txt-link-freetext" href="http://www.spnhc.org">http://www.spnhc.org</a> for membership information.
</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:
Staatliche Naturwissenschaftliche Sammlungen Bayerns
Zoologische Staatssammlung München
Dirk Neumann, Sektion Ichthyologie / DNA-Labor
Münchhausenstr. 21
81247 München
Besuchen Sie unsere Sammlung:
<a class="moz-txt-link-freetext" href="http://www.zsm.mwn.de/ich/">http://www.zsm.mwn.de/ich/</a>
---------
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:
<a class="moz-txt-link-freetext" href="http://www.zsm.mwn.de/ich/">http://www.zsm.mwn.de/ich/</a>
</pre>
</body>
</html>