Ref ID : 4561
Gabriele Scholten-Beck; Magnesium Starved Cells of Euglena gracilis - Possible Model System for Studying Mg2+ Influx? Z.Naturforsch. 51c:165-173, 1996
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In order to obtain a model which allows to directly study Mg2+ influx into the cell, Mg2+ deficiency was induced in the unicellular photoautotrophic flagellate Euglena gracilis. Lack of Mg2+ in the culture medium leads to a number of morphological, biochemical, and physiological changes in Euglena gracilis. The rate of cell division was reduced under Mg2+ -free conditions. Subsequently an enlargement of the cells was observed and they changed from spindle-like to oval shape. The Mg2+ -starved cells were well filled with paramylon granules, while their motility and vitality was not impaired. Concurrently with the larger cell size the protein-, carbohydrate-, and chlorophyll content of the cells increased. Further changes were observed in the surface carbohydrates. The proportion of cells with galactose, N-acetyl-galacosamine and mannose on the cell surface rose in the Mg2+ -starved cultures, shown in a lectin binding-assay. Fucose was found on the pellicle of Mg2+ -starved cells only. Cultivation of Euglena gracilis in Mg2+ -free medium induced a drastic reduction of the intracellular Mg2+ concentration already after 24 hr (from 233 nmol/10E6 cells to 82 nmol/10E6 cells). When Mg2+ was made available again, the Mg2+ -starved cells took them up rapidly and the intracellular concentration of free Mg2+ rose. As Mg2+ depletion could be induced in Euglena gracilis easily by manipulating the culture conditions and as the cells remained viable, it was concluded that this flagellate can be used as a model organism for studying the Mg2+ uptake of eukaryotic cells.