DNA isolation, amplification and agarose gel electrophoresis - these terms are no longer foreign to the first-semester students on the Physician Assistant course: in the annual genetics laboratory course, participants learn basic laboratory techniques, including methods for separating and analyzing DNA or RNA strands. “As genetics has become an integral part of our everyday lives and will continue to play an increasingly important role in the coming years, everyone should get to grips with the basic principles,” explains Laboratory Manager Daniel Eitel.
PCR: behind the scenes of a technology with a future
One of the basic techniques is the polymerase chain reaction (PCR), which can be used to quickly amplify selected DNA sections. The term has been on everyone's lips since the coronavirus pandemic, but very few people know what exactly is behind it. The Physician Assistant students were now able to take a look behind the scenes of this process - using a thermal cycler. What initially appears to be an unspectacular heating block is actually a device that can achieve large temperature differences in a very short space of time. Daniel Eitel first introduced the students to the three steps of a PCR cycle, as carried out in the course: As part of the experiment, a double-stranded DNA molecule is first separated into its individual strands by heating it to around 100 degrees Celsius. In the second step, so-called primers are bound to the individual strands at a temperature of around 45 degrees Celsius. These short pieces of DNA serve as starting points and specifically mark the regions that are to be amplified, for example a particular gene. Then, at around 70 degrees Celsius, the enzyme polymerase is used to complement each individual strand to form a complete double strand. In this way, a duplicate is created from a DNA molecule.
Horse or cattle ...? The students analyze unknown samples in groups
After this experience, the course participants were allowed to carry out this process themselves: Based on the horsemeat scandal in Europe in 2013, they were given the task of identifying a meat sample that was unknown to them. Group A was assigned an unknown horsemeat sample and Group B a beef sample. Each group was then divided into three subgroups: Group I undertook the DNA isolation, Group II the actual PCR, and Group III took care of the gel electrophoresis and analysis.
After successful PCR and electrophoresis, the analysis was carried out under UV light. The previously amplified DNA was colored with a fluorescent dye so that the students could see so-called bands glowing. Depending on the height of the band, this then spoke in favor of either cattle or horse in comparison with the positive control.
The bentolab of the GM-Lab (HNU's Health Management Laboratory) was used; a small unit consisting of a centrifuge, UV chamber, electrophoresis chamber and thermal cycler, which is just the size of a printer and can be used anywhere.
