X-Message-Number: 3139
Date: 14 Sep 94 14:04:30 EDT
From: yvan Bozzonetti <>
Subject: CRYONICS: membrane: Protect and repair

At low temperature, cell membranes undergo a phase transition and get 
broken and perforated. In an eucaryotic cell, membranes are made from a 
phospholipid bilayers with some proteins floating in, and a stiffing agent, 
the well known cholesterol.
	The main problem at low temperature is the lost of stiffness. 
Archeobacteria have no reinforcing molecules and no phospholipids, they 
exploit therpenoids such polymerized isopentenol. The polymerizing reaction 
could take place at the surface of a mineral, for example a clay crystal. 
That class of "primitive" products must be far more suited at the rough 
cryonics conditions than the soft cholesterol is.
	More: These primitive membrane molecules display their hydrophilic 
ends through ether bond and a glycerol residue. This glycerol element would 
presumably enhence the behavior at low temperature.
	The full story, with implications for the first days of life on 
Earth, can be found in the John Maddox article in Nature (vol. 371, 8 Sep. 
94, p. 101 ). The laboratory work was done by Guy Ourisson and Yoichi 
Nakatani at the Strasbourg CNRS laboratory for the organic chemistry of 
natural products in France, and was published in: Chemistry and Biology, 
vol. 1 p. 11-23, 1994.
	In cryonics, a dextran covered droplet of therpene could be 
targeted at the membrane cell and discharge here its stiffing cargo. This 
process could be exploited both, at the cooling phase to withstand freezing 
and at thawing to repair damaged membranes. That could be done at an 
intermediate temperature, near the -10 C -30 C range.
	In bacteria, cholesterol is remplaced by hopanoids kind molecules. 
We can so stiffen phospholipid bilayer membrane and/or substitute the 
phospholipids by therpenoids. Both, bacteria and archeobacteria withstand 
without problem any freezing conditions up to liquid nitrogen temperature. 
The key may be in their membrane structure.
	A first experiment could looks simply at archeobacteria in deep 
freezing conditions, so that the membrane state could be visualized.
	A second one, would disolve the bacteria (or archeobacteria) 
membrane in a powerfull detergent such Triton-X, centrifugate the resulting 
"soup" to recover the membrane fragments, dillute them to remove the 
detergent, sonicate with ultrasounds in presence of dextran and add this 
concentrated product at an eucaryotic cell culture. A freezing test would 
revals the practical possibilities of the method. That research seem to me 
simple to conduct in a biological laboratory, well defined without too much 
risk of deriving towards another subject and potentialy very rewarding.
	On a more general basis, the careful reading of scientific journals 
with a look at potential cryonics applications could be very usefull to 
discover new possibilities and solutions, often at low cost or without 
super hightech constrains. If each Cryonet reader could subscribe to one or 
two scientific publications, the science of cryonics would  benefits.

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