The Seven Stones

Proofreading, repair and robustness

THUMB070129.jpgHow do proofreading and repair activities emerge and what is their impact on system-level properties such as robustness or evolvability?

Biological networks and the Internet may share common architectural principles common to “robust yet fragile” systems (Doyle and Csete, 2007). But the Internet does not (yet) repair itself while cells or tissues do. Repair may represent an example of “downward causation” (The Music of Life, Noble 2006 or a book review) in which a high-level functional property (eg repair activity) emerging from a multi-component system (eg the DNA repair machinery) acts on a component at a lower level of organization (eg one nucleotide). In other words, could repair be considered as an example of a “cross-scale” feedback motif? Can these types of motifs be generalized and how would they evolve? The topic could in fact be extended to the field of synthetic biology: how to assemble synthetic systems with self-repair capability?

Many questions… Who has answers?

see also: Fidelity and infidelity (2001) Radman, 2001


  1. Report this comment

    Aditya Barve said:

    I wouldn’t consider this as Downward Causation. Whether one nucleotide or many, the abstract is the same. The system is acting on its basic material that ensures survival.

    It is a lower level of organization, yes! But I do not completely grasp your concept of cross-scale feedback.

    Nonetheless, Doyle’s view of robust yet fragile encompasses a different scenario. The idea is to understand which level of organization does the system trade-off in order to fixate on stability in another respect. This view basically says that there is a limit on the maximum level of robustness a system can achieve. If it uses is at one place, some of the robustness gets rubbed off from another level or process. This is not really surprising as the total amount of energy at a system’s disposal is fixed!

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