title: Freezing stresses and hydration of isolated cell walls.
abstract: The hydration of the cell walls of the giant alga Chara australis was measured as a function of temperature using quantitative deuterium nuclear magnetic resonance (NMR) of samples hydrated with D2O. At temperatures 23-5K below freezing, the hydration ratio (the ratio of mass of unfrozen water in microscopic phases in the cell wall to the dry mass) increases slowly with increasing temperature from about 0.2 to 0.4. It then rises rapidly with temperature in the few Kelvin below the freezing temperature. The linewidth of the NMR signal varies approximately linearly with the reciprocal of the hydration ratio, and with the freezing point depression or water potential. These empirical relations may be useful in estimating cell wall water contents in heterogeneous samples.
authors.affiliation: School of Physics, University of New South Wales, Sydney 2052, Australia.
authors.forename: Yonghyeon
authors.initials: Y
authors.lastname: Yoon
authors.forename: Jim
authors.initials: J
authors.lastname: Pope
authors.forename: Joe
authors.initials: J
authors.lastname: Wolfe
mesh_terms: D002469:Cell Separation; D002473:Cell Wall / Q000378:metabolism*; D044784:Chara / Q000166:cytology / Q000378:metabolism*; D017666:Deuterium Oxide / Q000378:metabolism; D005615:Freezing; D009682:Magnetic Resonance Spectroscopy; D013314:Stress, Mechanical; D014867:Water / Q000378:metabolism*
chemical_list: D014867:Water; D017666:Deuterium Oxide