Friedrich Bonhoeffer was born in Frankfurt, Germany, in 1932. Even as a young child, he knew he would become a scientist. His grandfather, Karl Bonhoeffer, was a noted psychiatrist and his father, Karl-Friedrich Bonhoeffer, was a famous physical chemist. “I was always interested in physics and chemistry,” he recalls. “I was very much the son of my father.” Bonhoeffer studied physics at the University of Göttingen, where he received his PhD in nuclear physics in 1958. His thesis was on beta decay and the mass of neutrinos. He didn’t stay in that field, however. Inspired by a lecture he had heard in Berlin by the German-American molecular biologist (and later Nobel Prize recipient) Max Delbrück, Bonhoeffer decided to give up neutrinos for nucleic acids. With the aid of a Fulbright scholarship, he journeyed to the United States to do postdoctoral research in the lab of biochemist Howard Schachman at the University of California, Berkeley.
At the end of 1960, Bonhoeffer returned to Germany to work with Alfred Gierer, a former physicist at the Max Planck Institute for Virus Research in Tübingen. He quickly got an offer to lead his own group at the neighboring Friedrich-Miescher lab of the Max Planck Society and soon thereafter became director at the Max Planck Institute for Virus Research (later renamed the Max Planck Institute for Developmental Biology). “When I came to Tübingen, I began by working on DNA replication, but when I became director of the institute I saw the chance of starting something completely new. I decided to switch to a field that did not really exist at that time,” he says. That field was axon guidance, the process by which axons of neurons grow and branch out to find their targets in the developing nervous system.
Throughout the 1970s and 1980s, Bonhoeffer made a series of pioneering contributions to understanding the molecular mechanisms behind axon guidance, including the development of key techniques that remain widely used today. His in vitro assays (tests that identify the biological activity of protein products) were particularly innovative, and he used them to uncover several fundamental axon guidance mechanisms. With his striped-membrane assay, for example, Bonhoeffer was able to give axons from different regions (nasal or temporal) of the chick retina the choice to grow on either the anterior or posterior membranes of the tectum (the main visual center in the brain of chicks). After demonstrating that temporal axons prefer to grow on the anterior tectal membranes, Bonhoeffer went on to show that axons were making their choices due to the repulsive action of the anterior membranes. “That surprised me,” Bonhoeffer recalls. “Until that point, we had thought that axons were guided to their targets by attraction, not repulsion.” These studies led to the identification, by Bonhoeffer and others, of the first known Ephrin guidance molecules, which are one of several fundamental axon-guidance mechanisms. More groundbreaking discoveries followed, including the identification of another repellent, RGM, and the execution of the first large-scale genetic screen for axon guidance mutants in zebrafish. Today, zebrafish serve as a model system for studying axon guidance, making possible a wide range of insights into the genetic mechanisms behind the process.
In 1984, Bonhoeffer became director of the newly founded Max Planck Institute for Developmental Biology, a position he held until his retirement in 2000. In his role as emeritus director, Bonhoeffer continues to stay involved with the institute, and expresses as much excitement about the latest advancements in axon guidance and developmental molecular biology as he did when he entered the field decades ago. “I still go to the office as often as I can and take part in discussions about latest findings from my younger colleagues,” he says.
Bonhoeffer’s work has been recognized by numerous awards and honors, including memberships in the German Academy of Sciences, Leopoldina, and the European Molecular Biology Organization, as well as the Fondation IPSEN prize for “axon guidance” with Corey Goodman and Marc Tessier-Lavigne. In 2007, he received the Society for Neuroscience’s Ralph W. Gerard Prize in Neuroscience for his lifelong contributions to neuroscience. Bonhoeffer lives in Tübingen, Germany with his wife, Dorothee. They have three sons.