Rules for the evoltuion of gene circuitry

摘要

Cells possess the genes required for growth and function in a variety of copntexts. In any given conext there is a corresponding pattern of gene expression in which some genes are OFF and others ON. The ability of cells to switch genes ON and OFF in a coordinate fashion to produce the required patterns of expression is the fundamental basis for complex processes like normal development and pathogenesis. The molecular study of gene regulation has revealed a plethora of melchanisms and circuitry that have evolved to perform what appears to be the same switching function. To some this implies the absence of rules. However, simple rules capable of relating molecular design to the natural environment have begun to emerge through the analysis of elementary gene circuits. Two of these rules are reviewed in this paper. These simple rules have the ability to unfiy understanding across several different levels of biological organization-molecular. physiological. developmental, ecological.