Undoubtedly, the polymerase chain reaction (PCR) has revolutionized biological research and has become one of the most common techniques in today’s laboratory. At times, it seems that a new variation of PCR is described in the literature every month. You might think that you are familiar with the dozens of PCR variations, but I am guessing that you haven’t heard of some of these.
- Inverse PCR
Amplification of flanking sequences by doing “outward” PCR of self-ligated genomic fragments.
- Perverse PCR
PCR performed by adding limiting amounts of primer at each cycle and using a different set of primers for each cycle.
- Reverse PCR
A procedure in which you start with a lot of a specific DNA and end with a small quantity of random DNA. This process is carried out with random primers, DNA polymerase and a carefully titrated excess of DNase I.
- Adverse PCR
PCR in which Klenow DNA Polymerase is used rather than a thermostable enzyme.
- Diverse PCR
A type of multiplex PCR in which multiple templates are each amplified with multiple primers, each of which has a different label. Awesome quantities of information can be collected from a single reaction if you can just figure out how to analyze it!
- Obverse PCR
A variant of reverse PCR (see above) in which the DNAse I digestion is allowed to go to completion. The final products of this reaction are dNMPs and PPi.
- Universe PCR
PCR performed with all possible primers present. Usually performed by people who heard that PCR “is a wonderful technique”, but have not quite got the hang of it.
- Free verse PCR
PCR performed with primers that will anneal to two entirely different regions of the template DNA. Yields are typically very low but interesting.