Dr Petter Holme (Coputational Biology)
This year is the 10th anniversary of the discovery that metabolic networks are scale-free. I will make a brief review of this decade of research relating network topology and function in metabolic reaction systems with a focus on our contributions. I discuss the hypothesis that network clusters correspond to functional modules. Metabolic network, however represented, are not as distinctly modular as the cartoon picture of intricately wired subsystems with few I/O-terminals. Does this reflect a trade-off between functionality and robustness, or is it an inevitable consequence of non-enzymatic reaction kinetics, or something else? I also discuss optimal levels of representations—if one uses a multiplex, directed, and perhaps bipartite, representation one can encode more information, but standard methods are harder to apply. If one goes for a simple-graph representation with vertices connected by undirected edges, then how can one encode as much functional information as possible? I will also mention how one can use other types of reaction systems, like reactions in planetary atmospheres, as null-models of metabolic networks. Finally I look forward and discuss open questions within reach with current and future data sets.