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. Rate This Message: http://www.cryonet.org/cgi-bin/rate.cgi?msg=3139