dnature diagnostics & research


Here you will find the musings of John.  Some of these were written almost a decade ago now but they remain relevant today.  We welcome your feedback.

Touchdown PCR

By John Mackay | 14/04/2022

Multiple reactions to run, each with their own preferred annealing temperature? Grabbed two primers of different Tm’s to amplify a region and trying to work out the best program? Touchdown PCR to the rescue. One of the best things to come out of Australia, it uses decreasing annealing temperatures during the cycling until it ‘touches […]

qPCR inventor and his NZ connection

By John Mackay | 07/10/2020

Originally published in May, 2014 ‘”we were interested to see if we could do it from hair . . .and we were the only ones around doing PCR” So you might have read the blog entry about the visit to see the first thermalcycler “Mr Cycle” at the Smithsonian. You haven’t? Sorry, another old blog […]

The solution (of your primers)

By John Mackay | 23/10/2019

Another old blog article – this one written originally in July 2010 : As PCR primers become less expensive, is there less care being paid to them? Throw in a diluent,a quick vortex and dilute for PCR? I hope this doesn’t sound too familiar because even in these days of real-time qPCR and various probe […]

This PCR is extremely Wittwer

By John Mackay | 14/08/2019

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 […]


By John Mackay | 20/06/2019

Designing primers for your high resolution melting is easy enough. A quick run with some known genotypes …. and look for the melting curve differences among samples. Too simple. But what about the temperature-neutral SNP’s? The what? A number of SNP’s ( ~ 4% in the human genome) have no affect on the melting temperature […]

Killing that DNA

By John Mackay | 08/11/2018

 You’ve done the hard work – you’ve got good quality RNA.  You’ve seen ribosomal bands on a gel (or *cough* Fragment Analyzer).  A good RQN/RIN (if that’s what you go by) and everything’s great. Now to get rid of the DNA Quick check (perform a PCR directly on appropriate amount of RNA) and often there’s […]

I have ‘what’ in my sample?

By John Mackay | 19/06/2017

Reagent contamination in PCR has long been documented – not only by operators but also from commercial sources long before those operators ever laid DNA-ridden hands on them. While contamination of some/many Taq polymerase enzymes with residual host E. coli DNA has had attention, little attention has been paid to the ubiquitous DNA extraction kits. […]