Fascinated by "Oddities" – Evolutionary Adaptations or Mutations Often Reveal Important Principles of Life, Says Peter Fabian

Peter Fabian is part of an international team that has received a prestigious Human Frontier Science Program grant to study the evolution of fish respiratory strategies. In this interview, you’ll learn about the fascinating labyrinth organ of the paradise fish, as well as other topics from the Fabian Lab through the lens of experimental biology.

 

The international research team you are part of has successfully applied for a prestigious grant from the Human Frontier Science Program, securing funding of $400,000 annually for three years as of March 2025. What significance will the project, made possible by this grant, have for the scientific community?

The Human Frontier Science Program grant is one of the most prestigious awards in basic research, with an application success rate of around 4%. The project connects entirely new teams; in our case, it involves linking our Fabian Lab with teams from Hungary and Japan. Each laboratory brings a unique approach—our focus is on cell sequencing, the Hungarian team specializes in developmental studies of fish, and the Japanese team works on evolutionary biology. The grant will enable us not only to conduct deeper experimental research into the evolutionary processes of fish respiratory strategies but also to organize symposia and facilitate mobility between the participating laboratories.

What are the main goals of your research?

This is a topic that only a handful of researchers worldwide focus on. Our goal is to better understand the various respiratory strategies in fish. While humans breathe through lungs and fish through gills, some fish species have developed unique organs that allow them to breathe in alternative ways. Approximately 80 methods have been described for how fish can breathe underwater without using gills. For example, carp, when in murky water with low oxygen levels, swims to the surface to take a breath because it lacks any special organ. This is unlike the fish we study.

Which fish and respiratory strategies are you specifically researching?

Adult individuals of the paradise fish (Macropodus opercularis) develop a special labyrinth organ that helps them process oxygen more efficiently. This improves their physical condition, survival rate, and ensures their offspring live longer. This organ represents a fascinating evolutionary adaptation that can yield essential insights into how organisms adapt to extreme conditions. Our project focuses on understanding the mechanisms behind the formation of this organ, factors influencing its development, and its biological significance. We aim to discover what triggers the development of this organ, which they are not born with, during their lifetime. It appears that this happens when they first swim to the surface to take a breath, but as I mentioned earlier, not all members of this species develop it. Those individuals who do not develop this organ weaken and die.

What does such a special organ look like in fish?

The aforementioned carp breathes through its gills, and water flows out through the operculum. Our unique fish has a different mechanism. Above or inside the operculum, it has a cavity where it traps air. It breathes using a special labyrinth organ that looks like a flower—it is twisted. Through this organ, it essentially supplements its oxygen intake.

How will you study the paradise fish?

We will analyze embryos and adult fish, isolate cells, and observe their behavior under different conditions. Using advanced technologies, we can determine what individual cells produce and how they contribute to the function of the labyrinth organ. For instance, we might discover that certain cells produce mucus to prevent the organ's surface from sticking or that they have a specific shape or function that enables them to separate structures for smooth blood flow.

How do you use experimental biology approaches in this research?

The information obtained will be compared with common fish, such as zebrafish, which lack this organ. We even plan to simulate conditions that could lead to the formation of a similar structure in zebrafish. This could help us understand the evolutionary mechanisms behind the development of this unique respiratory organ. This is a distant vision; it may not succeed at all, but it is our goal to understand the mechanism behind the creation of this extraordinary breathing organ.

What are the main challenges in this research?

One of the main challenges is identifying the factors influencing the formation of the labyrinth organ. We also need to ensure effective collaboration between international teams and harmonize different research approaches. Additionally, it is a technologically demanding project – from cell isolation to their analysis and simulations in model organisms.

What personally led you to natural sciences?

It's a classic story. I loved nature and animals, and I hated when they were killed. I was always fascinated by taking things apart because I wanted to understand how things work, I was interested in complex processes. And now I'm trying to connect the knowledge of how life works, how organs are formed in our body. That's what led me to developmental biology. The embryo fascinated me already in elementary school... I'm almost afraid to say it. I was lucky to have parents who supported my interests. Their support was crucial for me to pursue my goals. I am fascinated by "oddities" in nature – evolutionary adaptations or mutations often reveal important principles of how life works.

How can the emergence of these "oddities" be explained, such as the labyrinthine respiratory organ in some fish?

It is the result of evolution. This means that a certain trait has evolved, and the individual who has it survives better and longer. As a result, it has more offspring, and so this trait continues to spread. Of course, this is a simplified, mechanistic explanation for the purposes of this interview, but in principle it works.

What did you enjoy at school?

I enjoyed natural sciences, especially biology and chemistry. I also liked and still like propositional logic. I just love it. Those twists in mathematics, geometry – that always suited me. It's a typical teen life of a scientist – someone who enjoys it without realizing it.

How did I choose my field of study at university?

It came naturally – I was fascinated by biology and chemistry. That's why I went to study biochemistry at Comenius University in Bratislava. Our laboratory had good relations with Czech scientists, we collaborated. Thanks to that, I spent several summer holidays in the laboratory of the Institute of Parasitology of the Czech Academy of Sciences in České Budějovice. I learned new techniques and gained experience there. Thanks to this activity and work with cells, Julius Lukeš, who also works at the Institute of Parasitology of the Academy of Sciences of the Czech Republic, recommended me to the Department of Molecular Genetics in Prague at the Czech Academy of Sciences.

But let's go back to your postdoctoral experience...

I always say one thing: networking, networking, networking. We are social primates for whom the relational aspect is of enormous importance. It can move us much further than our individual performance. And it was thanks to networking and recommendations that I got further. After my doctorate, I went to America for six years. In Los Angeles, in Gage-e Crump's lab, I received further training in working with zebrafish. I learned the basics in Prague, but I deepened them in the USA. After completing my doctorate, I wanted to return to Central Europe. I like the Czech Republic – I gained part of my education there. And so it was natural to return here.

What helped you to progress further in your scientific career, specifically to Brno, to the Section of Animal Physiology and Immunology at the Department of Experimental Biology of our Faculty of Science?

Today, I don't spend as much time at the microscope as I used to. Most of the work with it is done by colleagues in our team. But the microscope is fascinating – we call it a "time machine." When you immerse yourself in it, hours fly by without you even noticing :-D. My start in Brno was really under a lucky star. When I arrived, we obtained the Dioscuri Center. This was one of three centers opened in the Czech Republic as part of the initiative of the German Max Planck Institute and the Czech Ministry of Education, Youth and Sports. One of them was assigned to our laboratory. I enjoy working at the Department of Experimental Biology very much. I have enormous support from the management, which is extremely important. The conditions here are fair. I know that when I come with a problem, I can solve it with my superiors. And we always reach a good solution. The team is relatively large, the spaces are more limited, but we learn to cooperate. We have regular social events, which helps create good relationships. We want to do top-notch science, but also maintain humanity.

Photo: Irina Matusevich

What does your Fabian Lab do?

We are building infrastructure for imaging techniques and genetic research. We focus on congenital genetic disorders. We model them on animals to understand their mechanism. For example, we work with alkaptonuria – a rare disease known as "black bone disease." Patients have darkening urine and degeneration of connective tissues. There are about 2,000 patients in the world, 200 of them in Slovakia. That is an incredibly high ratio. Brno is an ideal place for me – great conditions and proximity to Slovak patients. We are in contact with their organization and exchange information with each other. Mice as a model for this disease have failed – their bones did not darken. But our model on zebrafish faithfully mimics that phenotype. Thanks to this, we can study the mechanisms of this disease in detail. Science is about understanding the details – and we now have a tool to uncover them.

What would you like to say to young scientists?

Be curious and constantly ask how things work. Science is about discovering new things and overcoming obstacles. Have a passion for what you do and don't give up in the face of difficulties – these can take you further. Evolution is full of surprises.

Thank you for the interview.
Zuzana Jayasundera