BOSTON—To determine the impact of a potential drug on cell viability, researchers often rely on DNA labeling with a probe such as bromodeoxyuridine followed by fluorescent antibody-based detection. To get the antibodies to the nucleus, however, requires harsh treatments or nuclease digestion that can interfere with multiplexing with secondary probes, according to researchers from Harvard Medical School and Invitrogen's Molecular Probes division. To get around this problem, they replaced both the label and detection molecules.

 

As they explained in a poster at the recent SBS meeting, the researchers labeled DNA with ethynyl-deoxyuridine (EdU), which they detected by fluorescence under mild aqueous conditions using a Cu(I)-catalyzed azide-alkyne cycloaddition reaction with Alexa Fluor 488 azide dye. The new method was capable of monitoring DNA synthesis by imaging adherent cells or by flow cytometry, and could be coupled with a second dye to correlate synthesis with cellular morphology changes.