Annals of Botany 73: 481-491, 1994
© 1994 Annals of Botany Company
The Determination of Volume of Dunaliella Cells by Transmission Electron Microscopy and Image Analysis
Department of Biology, Royal Holloway, University of London, Egham Hill, Egham, Surrey, TW20 0EX, UK, Institut und Museum für Geologie und Paläontologie, Universität Tübingen, Sigwartstrasse 10, 72076 Tübingen, Germany and Department of Pathology, University of Vermont, College of Medicine, Medical Alumni Building, Burlington, Vermont, 05405, USA
A method has been developed to measure the cell volume of the unicellular, green alga Dunaliella bioculata 19/4 during salt stress conditions, where shape change in the alga becomes problematic and the cells can no longer be recognised as 'prolate ellipsoids', by using image analysis of transmission electron micrographs. The image analysis of the micrographs employs a specialised numerical integration programme or 'variable frames analysis' for unicellular microorganisms which possess a single axis of symmetry. Basic mathematics was used to determine: (a) the functional dependence of the calculated volume on the angle of the cut to the axis of symmetry and the distance of the origin of the cut from the centre of mass; (b) errors resulting from the orientation of the longest axis off-vertical for image analysis; (c) the uppermost range of calculated volumes obtained which represent the 'true' volumes within required confidence levels. The procedure was applied to a series of experiments on the effects of salt stress on Dunaliella bioculata cells.Copyright 1994, 1999 Academic Press
Dunaliella, image analysis, TEM, volume, variable frames, numerical integration, salt stress