title: First direct observation of the water exchange across the membrane of a single-cell green alga on a cellular level.
abstract: The isotopic water exchange across the membrane of a single-cell alga is made visible by optical differences of H2O and 2H2O. In the near infrared (NIR) (1000 to 2500 nm) H2O shows pronounced absorption bands while 2H2O is almost transparent. Results from in vivo experiments on the diffusive water permeation across the membrane of the spherical freshwater alga Eremosphaera viridis are presented. The evaluation of the isotope-exchange kinetics allows the calculation of the permeability coefficient, Pd, and the approximation of the intracellular diffusion constant, D. The extension of H2O/2H2O-exchange measurements to two dimensions opens new ways to study transport pathways up to the spatial resolution of a microscope. First NIR video images demonstrate the capability of the method.
authors.affiliation: Institute of Physical Chemistry, University of Würzburg, F.R.G.
authors.forename: R
authors.initials: R
authors.lastname: Lawaczeck
mesh_terms: D000465:Algorithms; D002462:Cell Membrane / Q000378:metabolism*; D000460:Chlorophyta / Q000166:cytology*; D013055:Spectrophotometry, Infrared; D014867:Water
chemical_list: D014867:Water