Determination of Thermal DNA-Stability With Respect to PCR or How to Debunk a Pseudoscientific Claim

Debunking pseudoscience is difficult, especially for early-career students and the public. Recently, in particular the Corona pandemic has spawned a whole range of pseudoscientific claims and conspiracy theories, many of which are publicly available in the style of scientific articles on preprint servers, in predatory journals, or in some cases even as regular scientific papers making it difficult to distinguish scientific papers from pseudoscience. One example is a recently published paper claiming that PCR is unreliable because DNA is thermolabile. While experts have the skills to recognize such pseudoscience, inexperienced early-career students usually have few chances to critically evaluate such claims. Here, we present some simple experiments that combine several aspects: (I) the analysis of a seemingly reputable publication, (II) planning experiments on the physicochemistry of DNA, (III) conducting and analyzing these experiments, and finally (IV) the refutation of the claim that PCR is unreliable. These experiments can be carried out in any standard laboratory with basic molecular biology equipment. They are therefore suitable for undergraduate programs and for high school courses. The model case described here enables students to critically evaluate these claims through practical investigations and to form their own informed opinion. The participants gained new insights into the planning of experiments and a completely new perspective on the subject of science and pseudoscience.