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Biological messiness relates to infidelity, heterogeneity, stochastic noise and variation—both genetic and phenotypic—at all levels, from single proteins to organisms. Messiness comes from the complexity and evolutionary history of biological systems and from the high cost of accuracy. For better or for worse, messiness is inherent to biology. It also provides the raw material for physiological and evolutionary adaptations to new challenges.
Excitatory synapses are located in confined chemical spaces called the dendritic spines. These are atypical femtoliter-order microdomains where the behavior of even single molecules may have important biological consequences. Powerful chemical biological techniques have now been developed to decipher the dynamic stability of the synapses and to further interrogate the complex properties of neuronal circuits.
Progress in understanding the functions of individual lipids has lagged behind that for other bioactive molecules, but recent technologies that enable the monitoring of individual lipids provide hope.
Because of the large number of phospholipids, their highly active metabolism and our lack of understanding of protein-lipid specificity, lipid signaling is a particularly challenging subject to study. Help might come from new tools that will allow us to follow and manipulate lipids and lipid-binding proteins in living cells.
Bioactive lipid signaling allows individual cells within the body to 'see' the surrounding environment and to respond in ways that will benefit the whole organism. Successful drug development for bioactive lipid targets requires a deep knowledge of the biology and pathobiology of each specific lipid signaling pathway.
Artificial biosynthetic pathways are typically assembled and optimized progressively, from earlier to later steps. This commentary highlights the potential of an alternate regressive method for biochemical pathway design and generation, inspired by the retro-evolution hypothesis and the concept of retrosynthesis. In addition to being a pathway design tool, 'bioretrosynthesis' has potential as a construction and optimization methodology.
