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Vaucheria sessilis (Vaucher) De Candolle ex Collins CCAP 745/1C
Dr. Roland Fleck, Institute of Freshwater Ecology |
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| Vaucheria is a widely dispersed organism, inhabiting freshwater, brackish and marine environments, filaments can be amphibious, living on mud that is periodically immersed in water then exposed to the air. Vaucheria is a member of the xanthophyceae and contains diadinoxanthin its major xanthophyll and lacks chlorophyll b (Whittle and Casselton, 1975) The alga V. sessilis forms branching, tubular coenocytic axes of an even thickness throughout (50-200um), the axes contain numerous discoid green chloroplasts and many nuclei. Filaments demonstrate apical growth and has conspicuous reproductive structures, with oogonia and antheridia being conspicuous on filaments. Cooling Rate: -1°C/min to either -35 or -60°C, Cryoprotectant DMSO 5% (v/v). Excised filaments were mounted between two coverslips in media (100ul). Filaments were first placed in media in shallow wells (10um deep) or in drops of media directly on the glass microscope coverslips (Chance Propper Ltd. No. 0). The top edge of the well or the outside edge of the cover slip was then lightly coated with silicone grease M494 (Ambersil Ltd.) and the filament was then sealed between two coverslips by placing a further glass microscope cover slip on top. This arrangement allowed a thin, uni-cellular layer of material to be examined without evaporation of the media. Ice front would be between -15 and -20°C in the media used (without nucleation). |
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