title: Levels of dinoflagellate chromosome-bound metals in conditions of low external ion availability: an x-ray microanalytical study.
abstract: Cells of the dinoflagellate Glenodinium foliaceum were able to grow and divide in artificial (AE50) liquid culture medium diluted down to 10% of its normal concentration. X-ray microanalysis, with on-line computation of mass fractions, was used to determine the quantitative occurrence of bound (insoluble) elements in the chromosomes of cells grown in normal, 30 and 10% medium. In normal medium, chromosomes contained high levels of phosphorus (nucleic acid), sulphur (protein) and a variety of bound divalent metals, including Ca, Fe, Ni, Cu and Zn. With a decrease in the level of external ions (30 and 10% dilutions), the level of sulphur showed a significant decrease, but the mass fractions of insoluble phosphorus and total divalent metals did not fall. The presence of these metals in dinoflagellate chromatin does not, therefore, simply involve intracellular deposition in response to high external levels. The occurrence of divalent metals showed variation with medium concentration in terms of the proportions of different metals present, the nature of the metal--nucleoprotein associations, the metal concentrations per unit mass of chromatin and the number of metal atoms per 100 nucleotides. None of the above characteristics is therefore constant in an individual species.
mesh_terms: D000818:Animals; D002118:Calcium / Q000032:analysis; D002875:Chromosomes / Q000032:analysis* / Q000648:ultrastructure; D003300:Copper / Q000032:analysis; D004141:Dinoflagellida / Q000648:ultrastructure*; D004577:Electron Probe Microanalysis; D007501:Iron / Q000032:analysis; D008670:Metals / Q000032:analysis*; D008854:Microscopy, Electron; D009532:Nickel / Q000032:analysis; D015032:Zinc / Q000032:analysis
chemical_list: D008670:Metals; D003300:Copper; D009532:Nickel; D007501:Iron; D015032:Zinc; D002118:Calcium