Staining the chromosomes of yeast by the Feulgen technique

Abstract

In spite of the recent controversy whether the Feulgen reaction stains the 'chromosomin' or the desoxyribose nucleic acid in the chromosome, the value of the above test for the identification of chromatin and chromosomes still remains unimpaired. This is more so in the case of the yeast, where volutin granules could easily be confused with chromatin. Kater describes and figures metachromatic granules both in parent and bud during metaphase and anaphase. On the other hand, Caspersson and Brandt showed that while in the resting cells the nucleic acid is confined to the volutin granules, in growing cells these granules disappear and the nucleic acid has a homogeneous distribution in the cytoplasm. The only cytological method of differentiating desoxyribose nucleic acid from the ribose type is said to be by Feulgen's nucleal reaction (Mirsky). Both volutin and chromatin stain by ordinary staining procedures, but only chromatin is stained by the Feulgen technique. Whatever may be the interpretation of the phenomena of nucleal reaction, the stained structure in the preparation is identified as chromatin. It appeared to us that a demonstration of the chromosomes of yeasts by the Feulgen technique would establish beyond doubt that yeasts have chromosomes and that these chromosomes conform in their behaviour to similar structures in higher plants.