divalent cations and PI
ZBIGNIEW DARZYNKIEWICZ (darzynk@nymc.edu)
Wed, 29 Nov 1995 09:34:24 -0500
Dr. Herron inquires as to whether Calcium or Magnesium ions affect
DNA stainability with PI. They certainly do. Accessibility of nuclear
DNA to most fluorochromes, especially the intercalating ones (and
thereby DNA stainability), is restricted by chromatin proteins,
primarily histones. Only a fraction of DNA is accessible to most
dyes, and this fraction varies depending on chromatin structure (cell
differentiation), mode of cell fixation and ionic composition of the
staining reaction (e.g. Cytometry, 5: 355, 1984). Interaction of
histones with DNA, which are primarily ionic in nature, are
influenced by divalent cations. The effect is less evident if the
staining protocols utilize detergents and proteolytic enzymes.
Zbigniew Darzynkiewicz
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