| Abstract: | The interchromatin granules (IG) are well characterized subnuclear structures in animal cell nuclei which form a part of the internal nuclear matrix and are supposed to correspond to accummulation sites of snRNPs and/or maturation and transport of rRNPs; but similar structures have not yet been characterized in plant nuclei. Using the bismuth impregnation technique of Locke and Huie, preferential for the staining of IG, we describe here a kind of positive granules 20–25 nm in diameter in plants. The putative plant IG have a series of common characteristics with animal IG, which are not found as a whole in any other subnuclear structures. These are: size, morphology and ultrastructural organization, presence in groups, EDTA and bismuth oxynitrate positive reactions, resistance to double digestion with proteases and RNase I and their high content in phosphorylated proteins. For all the above and also because they are ubiquitous structures in the plant nuclei, we identified these granules with the IG described in animal cells. |
