First Person is a series of interviews with the first authors of a selection of papers published in Journal of Cell Science, helping researchers promote themselves alongside their papers. Jessica Kehrer is first author on ‘ Clearing of hemozoin crystals in malaria parasites enables whole-cell STED microscopy’, published in JCS. Jessica is a PhD student in the lab of Friedrich Frischknecht at Heidelberg University Medical School, Germany, investigating malaria parasites using different microscopy and cell biology methods.

Jessica Kehrer

How would you explain the main findings of your paper in lay terms?

The life of a malaria parasite is very complex. Symptoms of an infection only occur when the parasite replicates within red blood cells. To do so, the parasite relies on the uptake of hemoglobin to extract essential nutrients such as amino acids. Hemoglobin degradation, however, leads to the formation of characteristic black hemozoin crystals; these are visible under the microscope and appear as dark structures inside the parasite. The high light-absorbing capacity of the hemozoin crystals makes imaging using super-resolution STED microscopy challenging. Therefore, I established a new method to make the parasite invisible and transparent by removing the hemozoin. Treatment of the parasite with the clearing reagent CUBIC-P now enables STED imaging without any restrictions, providing a great tool to understand parasite biology in more detail.

Were there any specific challenges associated with this project? If so, how did you overcome them?

I got the idea for this project while attending a microscopy conference not directly related to my general research topic. Surprisingly, there was no real challenge. The experiments mostly ‘just worked’. However, I think this is a great example of how much fun science can be if you have the chance to develop your own ideas and do not strictly focus on your narrow research topic only.

When doing the research, did you have a particular result or ‘eureka’ moment that has stuck with you?

I started working on this together with two talented master's students – Emma Pietsch and Julia Heinze, both co-authors on the paper. Out of curiosity we just wanted to perform a fun experiment on the side to see what CUBIC-P does with our parasites. We took some leftover parasites that we would have otherwise disposed of, fixed them and incubated them with the clearing reagent overnight. The following day, we went to a basic wide-field microscope to have a look at them, and the hemozoin pigment was indeed gone, meaning the parasites were completely transparent. This in the end set the basis for all follow-up experiments.

Why did you choose Journal of Cell Science for your paper?

Partly because Journal of Cell Science is a great journal for cell biology. Our lab has published here before and we always had positive experiences. Also, because the journal highlights Tools and Resources articles, we thought our new method would be a perfect fit for this section. On top of this, publishing is free of charge.

Have you had any significant mentors who have helped you beyond supervision in the lab? How was their guidance special?

Not really. However, I think I was extremely lucky that I always had the possibility to work with a lot of very inspiring people in the lab. I'm sure without some of them the days in the lab would have been less fun and exciting.

What motivated you to pursue a career in science, and what have been the most interesting moments on the path that led you to where you are now?

In school I was among the very few students in class interested in chemistry and biology; most of my classmates hated it. Hence, I started an apprenticeship as a chemical research assistant when I was 16. Yet, it was only when I was 23 that I decided to go to university to study biochemistry. For me, this was very special, since none of my family members had attended university before. After I completed my degree, it took me another 10 years in the lab of Freddy Frischknecht before my supervisor convinced me to finally register as a PhD student. During all these years, I have always enjoyed working in the lab doing fascinating experiments to discover new things. All this was only possible because Freddy never gave up pushing me in this direction.

What's next for you?

I'm planning on finishing my PhD sometime next year. Currently, there is no precise plan for what is next; however, I'm looking forward to exciting times ahead.

Jessica Kehrer’s contact details: Integrative Parasitology, Heidelberg University Medical School, Im Neuenheimer Feld 324, 69120 Heidelberg, Germany.


Clearing of hemozoin crystals in malaria parasites enables whole-cell STED microscopy
J. Cell Sci.