User: Pok Man Mendy Chan, Mount Sinai School of Medicine, New York
The project: Studying expression of G-protein coupled receptors in striatal neurons and their involvement Parkinson's disease.
The problem: Metabolically active tissue from postmortem brains in Chan's studies shows high levels of background fluorescence.
The solution: To examine coexpressed receptors at the single-cell level, Chan chooses as many as four dyes (Invitrogen, Carlsbad, CA) with nonoverlapping spectra, then fits in quantum dots (Evident Technologies) between dye-emission wavelengths for a maximum of eight colors per experiment. Because of their brightness, dots stand out against autofluorescence much better than dye, says Chan. Brightness is also advantageous when working with low-quality tissue such as tumor samples, says Sealfon. When using dots alone, he notes, the background can be bleached out with light exposure, he says. While organic dyes would fade along with the background under this treatment, quantum dots are largely immune ...
