Xanthine accumulation and vacuolization inChlamydomonas reinhardtii cells |
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Authors: | R. Pérez-Vicente M. I. Burón J. A. González-Reyes J. Cárdenas M. Pineda |
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Affiliation: | (1) Departamento de Bioquímica y Biología Molecular, Facultad de Ciencias, Universidad de Córdoba, E-14071 Córdoba, Spain;(2) Departamento de Biología Celular, Facultad de Ciencias, Universidad de Cordoba, Cordoba |
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Abstract: | Summary Utilization of xanthine as the sole nitrogen source for growth byChlamydomonas reinhardtii cells involved the formation of a transient, intracellular pool of xanthine. Up to 20% of the total xanthine supplied to the medium was not assimilated after uptake but stored in the cells at concentrations that exceeded xanthine solubility in water. At the subcellular level, a massive accumulation of starch grains in the chloroplast and the appearance of many vacuoles in the cytoplasm distinguished xanthine-grown from ammonium-grown cells. Starch accumulation, but not development of vacuoles, was also observed in N-starved cells. Uptake experiments with radio-labelled xanthine showed that this accumulates only in the cytoplasm, most probably inside vacuoles. The electron-dense material observed in vacuoles of xanthine-grown cells suggests that the intracellular xanthine is in part solid xanthine. |
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Keywords: | Chlamydomonas Accumulation Purines Vacuole Xanthine |
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