A Discussion with Nicolas Rohner, PhD

By Cathy Yarbrough

Nicolas Rohner, PhD, has been thinking about science since his childhood in Southern Germany.

“I learned everything I could about the plants, fungi, and animals in the forests near my home,” he said.

At the Friedrich-Alexander University (FAU) in Erlangen, Germany, Rohner majored in biology. Having decided on a career as an academic scientist, he earned an MSc degree at FAU and a PhD degree at the Max Planck Institute for Developmental Biology in Tübingen, Germany.

His mentor at Max Planck, the Nobel laureate Christiane Nüsslein-Volhard, PhD, introduced Rohner to fish as a model system for basic research in developmental biology. Rohner’s current research on the genetics of adaptation takes advantage of the attributes of an unusual species of fish, Astyanax mexicanus, commonly known as the Mexican cavefish. His postdoctoral studies of Astyanax in the laboratory of the renowned developmental biologist Cliff Tabin, PhD, at Harvard University have established this cavefish as an emerging model for studying comparative physiology and as an entry point for probing the genetic basis of metabolic disorders.

Mexican cavefish, which represent one of the most striking examples of adaptation in the animal kingdom, are the descendants of river fish that millions of years ago were swept by floods into dark underground caves. Because vision is useless in such environments, cavefish over time lost their eyesight. To survive long periods without food between the unpredictable floods that contain their only source of nutrients, cavefish developed a dramatically slower metabolism. They also developed the ability to feed to excess and accumulate large reserves of body fat—ten times more body fat than fish that live in the rivers near the caves, according to Rohner’s research at Harvard.

Rohner and his collaborators found that cavefish are able to live long and healthy lives even though they have high body fat levels, are insulin-resistant, and have unstable blood glucose levels—a condition similar to fatty liver disease and diabetes in humans. They also determined that the cavefish’s increase in appetite is due to a mutation in their melanocortin 4 receptor (MC4R) gene. This mutation is the most common single-gene cause of inherited obesity in people.

In 2015, Rohner completed his postdoctoral research at Harvard and joined the Stowers Institute, where he continues to use cavefish in research to provide insights into metabolic processes and diseases.

How could the results of your lab's basic research with cavefish prove relevant to human health?

In humans, diseases such as diabetes, allergies, and some types of cancer can result from a mismatch between our traits and biological processes and our current environment. In some ways, changes in our biology have not been able to keep pace with relatively rapid changes in our environment and lifestyle. By studying how cavefish have adapted successfully to their cave environment, we hope to identify the molecular mechanisms or genes that have evolved in these fish to allow them to survive and even thrive in extreme conditions. These genes and pathways that provide a protective function in cavefish may suggest therapies that could limit the impact of some diseases on human health.

What are the advantages of using cavefish over more established laboratory models such as fruit flies and mice?

Cavefish are a natural model whose metabolic changes are adaptive, not pathological. They occurred in such a way that other physiological changes happened to compensate for any detrimental consequences of the metabolic changes.

Studies with a natural model can complement research that focuses on laboratory animals with impaired metabolic responses. To understand the complex network regulating energy metabolism, both approaches are needed.

How often do you and your lab conduct field work in the cavefish's natural environment?

Through field work, laboratory scientists can obtain a better understanding of the role of environment in evolution and adaptation. Each year we try to spend about two weeks at a Mexican cave. It can be very challenging to visit—on our last trip, we spent four hours en route to the cave and occasionally had to use a machete to clear a path in the jungle. We used ropes to descend into the cave. At one point, we were attacked by killer bees, but finally getting to the fish was rewarding.

You have an appointment as an Assistant Professor at the University of Kansas Medical Center (KUMC). Are you working with the clinical researchers at KUMC?

Soon after I arrived at the Institute, I established research collaborations with leading diabetes researchers in the Department of Molecular and Integrative Physiology at KUMC. Through these collaborations, I am able to gain access to clinical studies and patient samples, which will facilitate the translational value of our work. I thrive from discussions with our KUMC collaborators— their expertise is absolutely crucial for my research.

How have you adapted to living in Kansas City?

Very well. Kansas City is a very easy city to live in and navigate—traffic here is like living in the 1950s but with modern cars. My wife, who is a lab manager in another lab, and I live just ten minutes away from the Institute.

Since I’m half French, I really enjoy good food and wine. Surprisingly, there is more authentic German and French food in Kansas City than there is in Boston.

Why do you participate in Social Media?

It’s important for my lab and me to have an online presence by using social media platforms such as Facebook and Twitter so that scientists and students who are interested in our research can connect with us. In particular, Twitter provides a platform that is connecting me with my peers and keeps me up to date about the latest research, discussions, and controversies in the field, important conferences, and recent papers—and everything is pre-digested into 140 characters or less.

Several scientific institutions in the US, Europe, and Asia offered you a faculty position. Why did you pick the Stowers Institute?

The Institute has unmatched core facilities and remarkable, brilliant faculty with complementary interests in genetics, developmental biology, and evolution. I also admire the American way of doing science. Here, the science often comes first, and the infrastructure surrounding it is designed to help achieve the scientific goals.