Singled out for sequencing

sequencing in 2013 Single-cell sequencing is no small feat. The amount of DNA or RNA in a single cell starts at a few picograms—not even close to the quantity that today’s sequencing machines demand. So scientists must amplify these molecules and do so in ways that minimize technical errors while surveying sequences as broadly and evenly as possible. Until recently, many researchers doubted that sequencing of single cells could be reliably conducted by any but a few experts. Although a handful of groups sowed the seeds for single-cell genome and transcriptome sequencing approaches years ago, the methods have more recently started to make their way to the masses, and a community has formed around their application in areas including neuroscience, cancer and microbial ecology. “Almost since the first day that PCR was invented, people began trying to use it to do single-cell gene expression and genome analysis,” says Stephen Quake at Stanford University, cofounder of Fluidigm. “But [single-cell sequencing] really is just taking off for a bunch of reasons.” Updated protocols for DNA and RNA amplification, especially those disseminated in the last two years, have given new biopsy and s ing le-cel l s equencing could correct ly infer both embr yo aneuploidy—too many chromosomes, as in the case of Down’s syndrome, or too few—and single-nucleotide varia-