This PCR is extremely Wittwer
August 14, 2019
OK, confession time. I used to work some crazy hours in order to fit some library screening into a part time job while finishing my degree. No, that’s not the confession – more, when I put the PCR on I would sometimes look out the window and note the wind direction. Occasionally, very occasionally (*cough*) if the wind was blowing in the right direction and looked right, I would walk home – paraglider in the car- drive out to the Otago Peinsula and if I was lucky soar above a beautiful beach for a couple of hours. Land, back it the car and 20 minutes later I’d be back in the lab to run the gel. Three to three and a half hours from putting on the PCR to running the gel.
About the same time Professor Carl Wittwer was exploring ways to make PCR faster – using air rather than formed blocks and capillaries rather than the standard 0.5ml that were common at the time. He and his team succeeded in reducing PCR times down to 10 minutes. He would soon become well-known for his qPCR developments of SYBR Green qPCR and melting curves which were available on his machine called the LightCycler. I was fortunate to work a lot with this machine at Roche Diagnostics – and would commonly be asked ‘what do they mean by 95 degrees for 0 seconds?’. The fastest assay I ever developed in the lab on the capillary instrument was about 14 minutes for 30 cycles. Not enough for paragliding, but maybe time for a cup of coffee.
And now that coffee time is under threat. . .
In this month’s Clinical Chemistry, Jared Farrar and Carl return to those original capillaries (very original, thinner than the Roche ones) and present Extreme PCR. . . . .if 10 minutes was termed rapid, then indeed 15 seconds is surely extreme. And that’s overstating it by a whole 6% if the fastest was actually 14.7 seconds.
How? A few facets all brought into play simultaneously: very fast temperature switching, high polymerase amounts (a standard enzyme working well but with a modified buffer) and high primer and Mg concentrations.
I won’t go into more details about possible ideas and applications because I was privileged to write the editorial for the paper and they are covered in both the paper and editorial. Oh there’s also a podcast where you can hear Carl talking about the process as well as some ‘New Zilind cultcha’ as well at the endpaper and editorial here
Listen to the Podcast here:
. . and for the extra curious: watch Extreme PCR in action…
Add a comment below about the speed of your own PCR testing – too slow? too fast? What you spend time doing while PCR runs?
