Interactions of fluorescent mercurial compounds and acidic fluorochromes with isolated living cells and nuclei

Two fluorescent mercurials (fluorescein mercuric acetate and merbromin) and two acidic fluorochromes (brilliant sulfoflavine and primuline) were tested as supravital fluorochromes and compared with the fluorescent “probe” for hydrophobic groups, 8-anilino-1-naphthalene-sulfonic acid (ANS). Neither the mercurials nor the acidic fluorochromes appeared to penetrate intact cells, but all of the dyes fluorochromed damaged cells in a characteristic fashion. Expriments were then undertaken on nuclei isolated in 0.25 M sucrose. The fluorescent mercurials produced fluorescence of the nuclear envelope and nucleoli. More generalized fluorescence was induced if nuclei remained for prolonged periods in saline solutions balanced for intact cells or in nuclei exposed to 0.2 N hydrochloric acid. Acidic fluorochromes produced a more generalized distributional pattern of fluorescence. Primuline produced substantially more intense nuclear fluorescence than brilliant sulfoflavine at equimolar concentrations. Considered as a whole, these results indicate that an examination of the interaction of fluorescent dyes with unfixed cellular components could prove to be a useful tool in cell biology, particularly in the investigation of nuclear function.