Nucleotide Content of the Nucleolus

Abstract

THE plasmosome type of nucleolus is the only commonly observed intranuclear structure which clearly is not chromatin, from which the nucleolus is easily distinguished by the fact that it gives a negative Feulgen nucleal reaction for desoxypentose nucleic acid. Although it is thus evident that the nucleolus probably does not contain the characteristic polynucleotide of chromosomes, the shape of the ultra-violet absorption curve shows that there is considerable nucleotide of some type in the nucleolus¹. The basophilia of the nucleolus is attributed to this nucleotide. It can be inferred that at least a part of the nucleolar nucleotide is ribonucleic acid from the fact that ribonuclease reduces the capacity of the nucleolus to bind basic dyes² ; but this conclusion is open to the objection that the nuclease used was probably contaminated with some protease activity³.