Étude ultrastructurale du cycle nucléolaire de Physarum polycephalum après mise en évidence préférentielle des RNP par la réaction régressive à l'EDTA

Abstract

Nucleolar cycle in Physarum polycephalum was studied using EDTA preferential stain for RNP. We have been able to establish the following. 1. 1. The nucleolar remnants that are observed during mitosis correspond to the fibrillar zones of the interphase nucleolus. 2. 2. In prometaphase and metaphase the nucleolar remnants lie peripherically around the chromosomal mass with which they are only superficially associated. 3. 3. Preribosomal granules appear 10–15 min after metaphase in the prenucleolar bodies. The results shown that the interphase nucleolus is an assembly of multiple subunits. The relationship between the nucleolar remnants and chromosomes is discussed in the light of the recent understanding of the extrachromosomal nature of rDNA.