New evidence on the robustness of metaboli...( EVANSTON Ill. --- Biological systems...)

EVANSTON, Ill. --- Biological systems are constantly evolving in ways that increase their fitness for survival amidst environmental fluctuations and internal errors. Now, in a study of cell metabolism, a Northwestern University research team has found new evidence that evolution has produced cell metabolisms that are especially well suited to handle potentially harmful changes like gene deletions and mutations.

The results, published online this week in the journal PNAS, could be useful in areas where researchers want to manipulate metabolic network structure, such as in bioengineering and medicine, and in the design of robust synthetic networks for use in energy production and distribution networks and in critical infrastructures, such as transportation networks.

The research was led by Julio M. Ottino, dean of the McCormick School of Engineering and Applied Science and Walter P. Murphy Professor of Chemical and Biological Engineering. Other authors of the paper, titled "Cascading failure and robustness in metabolic networks," are Lus A. Nunes Amaral, associate professor of chemical and biological engineering, and lead author Ashley Smart, who recently received his doctoral degree from Northwestern and is now a postdoctoral fellow at the California Institute of Technology.

Cell metabolism is essentially a large network of reactions whose purpose is to convert nutrients into products and energy. Because the network is highly interconnected, it is possible for a single reaction failure (which may be precipitated by a gene deletion or mutation) to initiate a cascade that affects several other reactions in the system. This event could be likened to disturbing a small area of snow that may trigger a large avalanche or the failure of a single transmission line in an electric power grid that may cause a widespread blackout.

By measuring the size of these "cascade" events in simulated metabolic networks, the Northwestern re
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