Layers of complexity

Delft Outlook, July 2010

Professor Sander Tans had his ‘eureka moment’ soon after gaining his doctorate in 1998. At the time, he and his supervisor, Professor Cees Dekker, were writing articles for leading journals such as Science and Nature about the electric charge of carbon nanotubes.

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“We were able to measure the electricity in individual molecules. That was fantastic! But the nanotools we developed could also be used for other things. They gave us a glimpse into the world of biological processes, all of which are very much more complex than anything we had studied so far. Motor proteins which repair DNA, for example, or which can move in and out of a cell along a special route. They are just as complex as any manmade motor, but at the nanometre scale. When you see this for the first time you think, ‘Wow! How is that possible?’”

This prompted Tans to opt for a career in biophysics, a discipline which he now practises as group leader of the biophysics laboratory at the Foundation for Fundamental Research on Matter’s Amolf (Atomic and Molecular Physics) laboratory in Amsterdam, and since 1 January as part-time professor in the new  bionanoscience department at TU Delft. Tans’ specialism is applying  the physicist’s perspective to biological topics.
His research field extends from the individual molecule to the level of cells and their evolution. Tans’ ambition is to help develop a more quantitative biology, a science based on testable hypotheses, experiments and predictable results. As an example, he cites his recent research into the mechanisms of evolution, in which a population of bacteria was ‘taught’ a new way of reacting to bacteria through an evolutionary process over some 100 generations. The researchers demonstrated that the bacteria adapted to a variable environment (in which antibiotics were sometimes present and sometimes not) through a combination of random mutations and Darwinian selection. “This was the first time that a new reaction was instilled by the process of evolution,” Tans reports. “We were also able to show what determines the success of this process. The research demonstrates that you can only really understand a process if you can reproduce it.”
Tans’ follow-up research is concerned with the evolution of complex characteristics. Most biological processes involve several different proteins. How do they change under the pressure of evolution? Or as Tans puts it, “How does complexity evolve? Can we distil some simple basic principles?” It has long been the physicist’s dream that enough study and research will reveal the logic which underpins our chaotic and complex reality. That dream has not yet been entirely realised in the field of physics itself.

More information:
www.tansgroup.amolf.nl