Figure 1.

Network-dosage compensation and specific topologies that are capable or incapable of facilitating network-dosage compensation. A. Cells having one- or N-copies of a general gene network. Each copy of the network is composed of a master transcription factor (encoded by the first gene, in green) of the cascade and additional components (blue, red, yellow genes driven by their own promoters carrying binding sites for the common TF). In turn, the expression levels of the additional network components can affect the activity of the network (purple dashed arrows). The network(s) in each cell is induced by an input signal. Depending on whether or not the network has the dosage-compensation capability, the two outputs can be similar or different. B-H. Dosage-compensated and non-compensated network structures. Green squares represent the transcriptional machinery that controls the expression of the two network components. B-C. Two network structures that are capable of dosage compensation. D. A network structure that is incapable of dosage compensation. E-H. Four network structures that could not be dosage compensated because the two network components have the same regulatory sign.