A Simple Device for Assuring High Reproducibility in Fluorometric Measurement of Deoxyribonucleic Acid in Yeast Cells

Abstract

The fluorometric micro-method of Kissane and Robins for measurement of DNA may be suitable for determining DNA contents of yeast cells, especially when only a limited number of cells are available, but for obtaining accurate results quantitative recovery of rather small amounts of cellular precipitates through washing procedure is a prerequisite. Although Simchen et al. applied this fluorometric method for measuring small amounts (0.2 .mu.g .apprx. 1.0 .mu.g) of DNA of the sporulating cells of Saccharomyces cerevisiae, experience here indicated that the procedure published gave reproducible results only when great care was taken to avoid loss of cellular precipitates in the course of repeated washings by centrifugation. Instead of collecting and washing the precipitates by centrifugation, an attempt was made to collect and wash them on a glass fiber filter and treat them in situ with the reagent. As shown below, this device, probably minimizing the risk of losing precipitates during washing, assures high reproducibility in measurement of relatively small amounts of yeast DNA.