Detection by bismuth staining of highly phosphorylated nucleo-proteins in plants. Determination of its specificity by X-ray microanalysis, SDS-PAGE and immunological analysis

Staining with bismuth salts after glutaraldehyde fixation is a very useful technique for preferential detection of phosphorylated nucleoproteins in mammalians and insects. In the present work we report an adaptation of this method for plant nuclei: staining with bismuth salts either in tissue blocks before embedding, or on thin sections of acrylic resin. Both procedures are highly reproducible and give the same pattern of staining in the nuclei in situ or isolated at the electron microscope. The specificity of bismuth binding to the dense nucleolar fibrillar component and interchromatin granules is proven by X-ray microanalysis. The nuclear proteins which bind bismuth have been identified by bismuth and immunostains of blots from total nuclear proteins. This technique is a very useful and specific cytochemical tool for studying nuclear organization and functions in plants.