X-Message-Number: 30185
Date: Thu, 20 Dec 2007 23:50:56 -0800 (PST)
From: 
Subject: Diamide enables freeze-drying

[It is widely assumed that fully reversible organ cryopreservation is a
technically easier task to complete than reversible organ
freeze-drying. Although I share in this assumption, nonetheless this
assumption may well be false, as the amazing results with diamide
illustrate here.]

Biol Reprod. 2003 Dec;69(6):1859-62. Epub 2003 Aug 6.
Tolerance of the mouse sperm nuclei to freeze-drying depends on their
disulfide status.
  Kaneko T, Whittingham DG, Overstreet JW, Yanagimachi R. Institute for
Biogenesis Research, Department of Anatomy and Reproductive Biology, John
A. Burns School of Medicine, University of Hawaii, Honolulu, Hawaii
96822, USA.
  Mouse spermatozoa from the caudae epididymides could be freeze-dried
without losing their ability to support normal development. Immature
spermatozoa from the testes, in contrast, were damaged by
freeze-drying. However, immature spermatozoa became resistant to
freeze-drying after their treatment with diamide, which oxidizes free -SH
groups. Conversely, epididymal spermatozoa were damaged by freeze-drying
if first treated with dithiothreitol (DTT), which reduces -SS- bonds. The
potential for freeze-drying damage seems likely to relate to the -SS-
status of sperm proteins, in particular its protamines.
PMID: 12904320

[It is also interesting here that dithiothreitol turned out to increase
freeze-drying damage.]

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