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Document IIF

Contraintes physiques dans des cellules à basses températures.

Physical stresses in cells at low temperatures.

Auteurs : WOLFE J., BRYANT G.

Résumé

Several physical stresses kill cells at low temperatures. Intracellular ice is almost always fatal, so survival of freezing temperatures involves combinations of dehydration, freezing point depression, supercooling and intracellular vitrification. Artificial cryopreservation achieves intracellular vitrification with rapid cooling, added cryoprotectants and modest osmotic contraction. High warming rates are required to avoid crystallization during warming. In the natural environment, cooling is much slower and temperatures less cold, but environmental freezing damage is important ecologically and agronomically. For modest sub-freezing temperatures, supercooling sometimes osmotic contractions. This contraction concentrates solutes and thus assists vitrification, but is not necessarily reversible. The rapid osmotic expansion during thawing may rupture membranes. Further, membranes and other ultrastructural elements may be damaged by the large, anisotropic mechanical stresses produced when their surfaces interact via hydration forces. Solutes reduce these stresses by osmotic, volumetric and other effects.

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Détails

  • Titre original : Physical stresses in cells at low temperatures.
  • Identifiant de la fiche : 2000-1620
  • Langues : Anglais
  • Source : 20th International Congress of Refrigeration: Refrigeration into the Third Millennium.
  • Date d'édition : 19/09/1999

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