X-Message-Number: 13197 Date: Fri, 4 Feb 2000 13:36:02 -0800 (PST) From: Doug Skrecky <> Subject: new cell dessication methods I'd like to thank Brent Thomas for posting the trehalose article. This has been a long time in coming. It has been known for many years that accumulation of intracellular trehalose (or sucrose) is critical for small animals as well as plants to survive complete dessication. The methods for permeabilizing cells so as to allow large solutes to pass through cell membranes have also been known for years. I'm glad to hear these two areas of knowledge have finally been brought together to acheive some success. The only problem blocking the the achievement of reversible organ cryopreservation is cryoprotectant toxicity. Large amounts of toxic solutes like dmso, glycerol, and ethylene glycol kill cells through various not-well-understood mechanisms. Perhaps this is a case of less being more. A small amount of cryoprotectant combined with dessication might achieve the goal of organ vitrification that some cryobiologists have been searching for, for so many years. Below is an interesting article on glycerol. ---------- Forwarded message ---------- Authors Shen B. Hohmann S. Jensen RG. Bohnert aH. Institution Department of Plant Sciences, The University of Arizona, Tucson 85721, USA. Title Roles of sugar alcohols in osmotic stress adaptation. Replacement of glycerol by mannitol and sorbitol in yeast. Source Plant Physiology. 121(1):45-52, 1999 Sep. Abstract For many organisms there is a correlation between increases of metabolites and osmotic stress tolerance, but the mechanisms that cause this protection are not clear. To understand the role of polyols, genes for bacterial mannitol-1-P dehydrogenase and apple sorbitol-6-P dehydrogenase were introduced into a Saccharomyces cerevisiae mutant deficient in glycerol synthesis. Sorbitol and mannitol provided some protection, but less than that generated by a similar concentration of glycerol generated by glycerol-3-P dehydrogenase (GPD1). Reduced protection by polyols suggested that glycerol had specific functions for which mannitol and sorbitol could not substitute, and that the absolute amount of the accumulating osmoticum might not be crucial. The retention of glycerol and mannitol/sorbitol, respectively, was a major difference. During salt stress, cells retained more of the six-carbon polyols than glycerol. We suggest that the loss of >98% of the glycerol synthesized could provide a safety valve that dissipates reducing power, while a similar high intracellular concentration of retained polyols would be less protective. To understand the role of glycerol in salt tolerance, salt-tolerant suppressor mutants were isolated from the glycerol-deficient strain. One mutant, sr13, partially suppressed the salt-sensitive phenotype of the glycerol-deficient line, probably due to a doubling of [K(+)] accumulating during stress. We compare these results to the "osmotic adjustment" concept typically applied to accumulating metabolites in plants. The accumulation of polyols may have dual functions: facilitating osmotic adjustment and supporting redox control. Rate This Message: http://www.cryonet.org/cgi-bin/rate.cgi?msg=13197