Biological consequences of dosage dependent gene regulatory systems.

Chromatin and gene regulatory molecules tend to operate in multisubunit complexes in the process of controlling gene expression. Accumulating evidence suggests that varying the amount of any one member of such complexes will affect the function of the whole via the kinetics of assembly and other actions. In effect, they exhibit a "balance" among themselves in terms of the activity of the whole. When this fact is coupled with genetic and biological observations stretching back a century, a synthesis emerges that helps explain at least some aspects of a variety of phenomena including aneuploid syndromes, dosage compensation, quantitative trait genetics, regulatory gene evolution following polyploidization, the emergence of complexity in multicellular organisms, the genetic basis of evolutionary gradualism and potential implications for heterosis and co-evolving genes complexes involved with speciation. In this article we will summarize the evidence for this potential synthesis.