Editiorial from BioCompare
Author: Caitlin Smith
Several decades ago, would scientists have laughed if you told them that you knew how many molecules of DNA were in a tube? Perhaps—but not today. It may have been nearly unimaginable to scientists of the past that we could count anything so tiny. But with a new technique called digital PCR (dPCR), today’s scientists can indeed count molecules of DNA.
Digital PCR derives its name from the method of counting. Researchers partition a sample of template DNA into many tiny partitions, such that each one essentially contains either 0 or 1 copy of template DNA. Counting the positive wells gives an absolute number of molecules in the original sample. In general, the more partitions a sample is divvied up into, the better the precision and the wider the dynamic range of measurement.
Using dPCR rather than its predecessor, qPCR, researchers are better able to measure small changes in amounts of DNA in a sample. For example, dPCR can distinguish between say, five and six copies of a gene, a feat of detection that is out of qPCR’s league. Scientists use dPCR to detect and quantify low-level pathogens, rare genetic sequences or mutations and copy-number variations, among other applications.
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