An evaluation of the standards used in the study of the yeast nucleus

Abstract

1. In the brewery yeast BY 1, the nucleus is visible in 1-2% of the cells from 6-8-day cultures in barley malt wort and 0·5-1% of the cells from 10-12-day cultures in Galactose Peptone Yeast extract medium. 2. The nucleus is extra-vacuolar and is delimited from the cytoplasm as well as the vacuole by a definite nuclear membrane. 3. Under phase contrast, the nuclear matrix shows gradations in optical density. 4. Using the living nucleus as the standard, the variations in its structure are illustrated from iron haematoxylin and Feulgen stained preparations of hydrolysed cells. 5. The vacuole shows no stainable inclusions and leuco-basic fuchsin stains only limited regions of the resting nucleus.