When I remember the 80s, I think of Nena’s 99 Luftballons, Duran Duran’s Wild Boys and ….snake venom. Back in those days, I used to be a typical high school science nerd. My science nerdiness interfered with my ability to socialize with non-nerds and it was characterized by an unnecessary desire to read science books and articles that I did not really understand, just so that I could show off with some fancy science terminology. I did not have much of an audience to impress, because my class-mates usually ignored me. My high school biology teacher, Herr Sperr, was the only one who had the patience to listen to me. One of the science books that I purchased was called “Gehirn und Nervensystem” (i.e. “Brain and Nervous System”), published by Spektrum der Wissenschaft, the German publisher of Scientific American. It was a collection of Scientific American articles in the field of neuroscience that had been translated into German. I was thumbing through it, looking for some new neurobiology idea or expression that I could use to impress Herr Sperr. While browsing the book, I came across the article “Der Nervenwachstumsfaktor” (originally published in Scientific American as “The Nerve-Growth Factor” in 1979) by Rita Levi-Montalcini and Pietro Calissano.
My curiosity was piqued by this article, because I did not realize that nerves had “growth factors” and because one of the authors, Rita Levi-Montalcini, had just won the Nobel Prize in the preceding year. I started reading the article and loved it, reading it over and over again. I liked the article so much, that I did not even try to show off about it and kept the newly discovered inspiration to myself. There are many reasons why I loved the article and I will just mention two of them:
1. Scientific discovery is an exciting journey, starting and ending with unanswered questions
Levi-Montalcini and Calissano started off by describing the state of knowledge and the unanswered questions in the field of developmental neurobiology and neuronal differentiation in the 1940s, when Levi-Montalcini was about to launch her career as a scientist. They commented on how the simple yet brilliant idea to test whether tumors could influence the growth of nerves sparked a whole new field of investigation. They narrated a beautiful story of scientific discovery, from postulating a “nerve growth factor” to actually isolating and sequencing it. Despite all the advances that Levi-Montalcini and her colleagues had made, the article ended with a new mystery, that the role of the nerve growth factor may be much bigger than all the researchers suspected. The nerve growth factor was able to act on cells that were not neurons and it was unclear why this was the case. By hinting at these yet to be defined roles, the article made it clear that so much more work was necessary and I felt that an invitation was being extended to the readers to participate in the future discovery.
2. Scientific tools can harbor surprises and important clues
The article mentioned one important coincidence that helped shape the progress of discovering the sequence of the nerve growth factor. To assess whether the putative nerve growth factor contained nucleic acids, Levi-Montalcini and her colleagues exposed the “soup” that was inducing the growth of nerves to snake venom. The rationale was that snake venom (by the way, the German expression “Schlangengift” sounds even more impressive than the English “snake venom”) would degrade nucleic acids and if the growth enhancing properties disappeared, it would mean that the nerve growth inducing factor contained nucleic acids. It turned out that the snake venom unexpectedly magnified the nerve growth enhancing effects, because the venom contained large quantities of the nerve growth factor itself. This unexpected finding made it much easier for the researchers to sequence the nerve growth factor, because the snake venom now provided access to a large source of the nerve growth factor and it resulted in a new mystery: Why would snake venom contain a nerve growth factor?
In the subsequent decades, as I embarked on my own career as a scientist, I often thought about this article that I read back in high school. It inspired me to become a cell biologist and many of the projects in my laboratory today focus on the effects of growth factors on blood vessels and stem cells. The article also made me think about the importance of continuously re-evaluating the tools that we use. Sometimes our tools are not as neutral or straight-forward as we think, and this lesson is just as valid today as it was half a century ago. For example, a recent paper in Cell found that the virus used for reprogramming adult cells into stem cells is not merely a tool that allows entry of the reprogramming factors, as was previously thought. The virus tool can actually activate the stem cell reprogramming itself, reminiscent of how the “snake venom” tool was able to induce nerve growth.
Rita Levi-Montalcini was one of the world’s greatest biologists and passed away on December 30, 2012. In addition to her outstanding scientific work, she was also a shining example of an activist scientist with a conscience, who fought for education and research. I never had the opportunity to meet her in person, but I was inspired by her work and I will always see her as a role model.
Image credit: Cover of the book “Gehirn und Nervensystem” by Spektrum der Wissenschaft
The Next Regeneration 