Our new Biological Modelling section: interview with board members Ralf Metzler and Joachim Krug

We are delighted to announce that Journal of Physics A: Mathematical and Theoretical now offers a dedicated publishing venue to those researchers working in the interdisciplinary field connecting biology and biochemistry with the underlying physical and mathematical models.

Ralf Metzler

Ralf Metzler

The new section will be broadly overseen by the new section editor Ralf Metzler, and additionally Yariv Kafri and Joachim Krug who we are pleased to announce as new members of the journal’s editorial board.

Joachim Krug

Joachim Krug

Metzler is based at the University of Potsdam, and has worked on the JPhysA editorial board since 2010 while Krug works at the Institute of Theoretical Physics at the University of Cologne. Kafri is from the Department of Physics at Technion, his research group broadly focus on statistical mechanics and its applications, though they have recently taken an interest in biological and far from equilibrium systems. 


We asked Ralf Metzler and Joachim Krug a few questions about their careers and research.

You specialise broadly in statistical mechanics of complex systems and more specifically stochastic processes and anomalous diffusion. Additionally you carry out a lot of work on biophysical systems. What led you to this area of research?

RM: At the beginning of my work on anomalous diffusion fundamental questions were the driving force: for instance, how can we phrase a dynamic equation for anomalous diffusion in which an external potential is built in automatically?

In my more recent work the initial motivation comes mainly from modern experimental techniques such as superresolution microscopy or single particle manipulation. The possibility to trace individual steps in processes such as gene regulation or the motion of proteins in living biological cells is extremely fascinating, similar to the ability to probe the shape of a DNA chain that collapsed on a surface, or the force-extension behaviour of a single molecule.

As theorists it is our job to provide qualitative and, where possible, quantitative models to understand the measured results or predict good parameter values for future experiments.

What are you currently working on?

JK: I am generally interested in how populations of simple organisms (such as bacteria) adapt to their environment. According to the Darwinian paradigm, this occurs by favorable genetic variants spreading in the population, a process that is usually highly stochastic. Specifically, we study interactions between different genetic mutations, where the presence of one mutation influences the effects of another. In this way certain mutational pathways (defined as a series of mutations that occur sequentially) become more likely than others, rendering the adaptive dynamics predictable to some extent. An important application is to the evolution of antibiotic resistance. We collaborate closely with experimental geneticists who provide us with data and test the predictions derived from our models.

What would you say has been your career highlight or biggest achievement to date?

RM: Of course, it would be nice to point out a specific paper, but I see achievement more in the continued discoveries made in a specific topic. For instance, the insights we have obtained in anomalous diffusion theories over the years has become a body of work that I quite like. Similarly, we are trying to put together a better picture of the spatiotemporal dynamics behind molecular gene regulation or the effects of molecular crowding on physical processes. 

What do you consider to be the most significant problem to be addressed in your field? 

JK: This is hard to answer. The holy grail in evolutionary biology is of course to understand how the genetic makeup of an organism (its ‘genotype’) connects to the properties that are important for its survival and reproduction (the ‘phenotype’), but since this relation encompasses essentially all of biology, it is not a problem that can be expected to be ‘solved’ in any reasonable sense. In view of the daunting complexity of biological systems, it is already a challenge to formulate questions that can be meaningfully addressed by quantitative theory, and that can be tested experimentally in a biologically relevant context. For example, do large populations adapt more efficiently than small ones, and does it help adaptation if individuals exchange genetic material? These are some of the problems that workers in my field try to explore, and that require close interactions between  theory and experiment.

You have worked on journal editorial boards for some time now, how have publishing habits changed in that time?

RM: The pressure on scientists has increased over the years, as many of us feel. In this rat race the success of researchers is, to a large extent, measured in terms of the number of publications and the quality of the journals’ impact factors. More paper submissions, also due to an increasing number of authors overall, puts the peer review system under pressure and often results in less useful micro-reports or opinion statements. Sometimes aggression takes over in reports. How long this will continue? I am not sure. The fact that so many papers can no longer be digested should make us think. An increasing number of universities are unable to afford access to even the most vital journals. Maybe an increased pressure towards open access may help, as the cost of publishing will lead to a reduction of papers. How this can be done such that financially less equipped institutions are not disadvantaged, is another question.

On the whole I like journals such as JPhysA, they are aware of potential biases and have a thorough reviewing process. Many colleagues agree that they feel taken more seriously with JPhysA than with many other journals they submit to. This is also one of the reasons why I enjoy working on the JPhysA editorial board so much.

Finally, do you have any advice for young researchers entering the field?

RM: This is an extremely exciting period of research, especially in small systems. Experimentalists have reached dimensions that sounded like science fiction when I first started in research. I also believe that quantitative theoretical physics has a very bright future. Sure, it is not easy to launch a career as a scientist, but it is definitely worth trying it.

JK: The interface between evolutionary biology and statistical physics currently offers great opportunities for creative minds, with the potential to make contributions of lasting impact. As in any interdisciplinary field, it is very important to learn and understand the language and the way of thinking of the other discipline (in this case, biology), which works best through personal interactions. I would therefore advise anyone who wants to work in this area to seek out places where such interactions are already taking place. Beyond that, follow your own predilections without too much regard for strategic considerations.

Biological Modelling section scope

UntitledThe Biological Modelling section publishes high quality articles using mathematical modelling to study problems in the interdisciplinary field connecting biology, biochemistry and physics. The section accepts contributions on topics ranging from single molecules and their interactions to populations of organisms and animals.

  • Active systems
  • Interactions and dynamics in single molecules
  • Stochastic modelling
  • Fluctuations (including fluctuation theorems) in biological and biochemical systems
  • Intra- and intercellular signalling including gene regulation and quorum sensing
  • Search processes
  • Biological networks and their dynamics
  • Modelling of systems and synthetic biology
  • Populations dynamics, disease spreading and movement ecology

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This work is licensed under a Creative Commons Attribution 3.0 Unported License. Images courtesy of Ralf Metzler and Joachim Krug. Featured image from Pixabay licensed under Creative Commons CC0.

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