Modularity and Dynamics of Cellular Networks is a review of developments affecting the analysis of cellular dynamics. The review centers around cellular networks as analyzed from a modular perspective. We're accustomed to explanations of cellular functions that are focused on particular interacting molecular components as would be the case, for example, of an enzyme and its substrate or transcription factors and their binding sites. This paper is focused on results enabled by technologies that have made it possible to view cellular events on a global scale. A related goal was deriving "underlying principles of how complex cellular networks are built and how network architectures contribute to phenotypes."

By substituting phrases in place of the biological nomenclature found parts of the article, one could get the impression the article was about a computer program, a mechanical device or efficient manufacturing techniques. Note a description of transcriptional network motifs which "include feed-forward loops, single-input motifs, and multi-input motifs. A feed-forward loop describes a situation in which a transcription factor (TF) regulates a second TF, and these two TFs jointly regulate a common target gene." A metaphor to a manufacturing technique refers to protein complexes formed during the cell cycle which suggest "a general mechanism of "just-in-time-assembly," where only some subunits of protein complexes are regulated during cell cycle progression and the synthesis of these subunits control the timing of complex assembly. "Just-in-time-assembly" may be a more efficient way of regulation compared with "just-in-time-synthesis," in which case all subunits of protein complexes are regulated and synthesized at the same time during the cell cycle."

Modularity might have a familar ring to it for those of you who have kept abreast of debates between advocates of intelligent design and their mainstream critics. In response to Michael Behe's concept of irreducible complexity his critics cited precursor candidates in evolutionary pathways to structures like the flagellum. Cooption of already existing subsystems was posed in answer to Behe's conundrum.

'Modularity and Dynamics of Cellular Networks' takes a broader view of cellular networks and structures. In posing questions like "what are the characteristics of cellular network structures that distinguish them from randomly generated networks? Are the network structures relevant for biological functions? If so, are they evolutionarily conserved and how do they evolve?" the authors may be touching on more fundamental approaches to the source of biological complexity. If, as the authors suggest, properties of cellular networks, rather than isolated components, best explains many phenotypes and behavoirs, then data linked to the selective value of networks should yield the better explanations.

So how might this impact competing paradigms? Selected, random mutations are focused on the cumulative effects of changes to individual genes. The process is local not global but would be used to bridge to sub-modules and individual proteins. A network or module approach is a good fit for models built around the belief that certain features of living organisms are best explained by intelligent causality or, as Mike Gene might put it, the contention that life was designed to evolve.

This entry was posted on Wednesday, January 10th, 2007 at 2:41 pm and is filed under Intelligent Design, Irreducible Complexity, The Debate. You can follow any responses to this entry through the RSS 2.0 feed. You can leave a response, or trackback from your own site. The trackback link is: http://telicthoughts.com/modular-selection-patterns/trackback/