#LabHacks: Picky Science
Looking at the illuminated clean bench in Ernst Jarosch’s laboratory takes me right back to my parents’ dining room. They used to have a similar utensil to the one that catches my eye here in the lab – a toothpick dispenser. The one my parents had was a cylindrical plastic box with a red bottom half and a transparent screw lid on top. The little wooden helpers were packed tightly inside, all lined up and waiting to be of service.
The “toothpick dispenser” in Ernst Jarosch’s lab looks very similar, except that the toothpicks are in a small glass cylinder and covered with an aluminium cap. “These toothpicks are autoclaved, which means sterile”, explains the scientist who works in the research group headed by Prof. Thomas Sommer. Jarosch and his team are using these old-fashioned cleaning tools to take samples from bacterial colonies.
Tips of toothpicks are ideal for sample collection
The bacteria grow on nutrient medium plates. The problem is that there are often so many colonies on one plate that it is difficult to take samples from these individual piles of cells. But, as Jarosch explains, it is important to do exactly this: “The colonies have different DNA. When we take samples from individual colonies it is very important that these are not ‘contaminated’ by other colonies. That’s why we use toothpicks to collect the samples. They have very sharp tips which makes them ideally suited to the task.”
Every toothpick with a sample on it is put into a test tube containing a special nutrient solution. This is mixed with an antibiotic primarily used in research. The bacteria on the toothpick contain a plasmid (a piece of extra-chromosomal DNA) which includes a gene for developing a resistance against the antibiotic. Only bacteria with an upholding cell functionality plasmid can therefore grow in the nutrient solution. “We use these bacteria as a kind of factory to reproduce a specific DNA that we need, because the microorganisms multiply exponentially in the solution and we therefore get large amounts of it in a short space of time,” says Ernst Jarosch.
Transforming other systems with the cultivated DNA
In the next step, the reproduced DNA constructions are introduced into yeast cells in order to investigate their impact on specific biological processes in this organism. Jarosch and his team can use this method to trigger targeted changes in an enzyme complex of these yeast cells, for example. These kinds of experiments provide information on the organization of protein complexes and allow conclusions to be drawn on the function of the individual components. Thomas Sommer and his team are investigating the degradation of erroneous proteins in the secretory pathway, which contributes substantially to the prevention of cellular stress and is thus an important process in retaining cell functionality.
I distinctly remember how much I disliked using toothpicks when I still lived with my parents – they always seemed to splinter or break between my teeth. It makes perfect sense to me, however, that their pointed tips can be extremely useful for top-level research.
Contribution pictures by Editorial team/MDC
