Laser flow measurements of scattering and fluorescence from cell nuclei in the presence of increasing Mg++ concentrations.
The effects of Mg++ on the spatial organization of nuclei from rat hepatocytes are analyzed in the range 0-60 mM, in the presence of suitable concentrations of KCl to reproduce physiological conditions. It is shown that the scatter-signal distribution measured by means of a flow microfluorimeter is greatly affected by this range of Mg concentrations. By coupling this result to phase-contrast-automated image analysis, it is possible to identify a shrinking process induced by Mg++ in the range 0-2.5 mM, which reaches a plateau in the range 5-20 mM and is followed by a swelling process in the range 30-60 mM. The same Mg ranges are shown to affect the intercalation of the fluorochrome acridine orange into chromatin, suggesting that the shrinking-swelling phenomenon has also a molecular correspondence at the genome level. Possible implications in terms of the influence of Mg++ on the organization of chromatin inside intact cells are briefly discussed.
D000165:Acridine Orange; D000818:Animals; D002467:Cell Nucleus / Q000187:drug effects / Q000648:ultrastructure*; D004305:Dose-Response Relationship, Drug; D005470:Fluorometry; D007834:Lasers; D008099:Liver / Q000648:ultrastructure*; D008274:Magnesium / Q000494:pharmacology*; D008297:Male; D008858:Microscopy, Phase-Contrast; D011189:Potassium Chloride; D051381:Rats; D011919:Rats, Inbred Strains; D012542:Scattering, Radiation
D011189:Potassium Chloride; D000165:Acridine Orange; D008274:Magnesium