Topologies, synthetic implementations and expression profiles of the networks studied Topologies, synthetic implementations and expression profiles of the networks studied Topologies of the networks using the opposing gradients (left) and concurring gradients (right) mechanisms. Arrow: activation; small horizontal arrow: constitutive promoter; bar: repression; red: morphogen input receiver gene; blue: intermediate loop gene; green: stripe output gene.Synthetic implementations of the circuits (Schaerli et al, 2014). Open rectangle: open reading frame; filled rectangle: operator; bent arrow: promoter. All genes carry a degradation tag [LVA (Andersen et al, 1998) or UmuD (Gonzalez et al, 1998)]. Indicated variants of T7 promoter, SP6 promoter and LacO were used (Schaerli et al, 2014). J23114 and J23100 are constitutive promoters (http://partsregistry.org/Promoters/Catalog/Anderson).Rectangles: Schematic drawings of spatiotemporal course of gene expression (colour‐coded) as in (A) for the two networks (see Box 1). The expression level of the “green” gene is the phenotypic “output” of the network. Corresponding simulations (Code EV1) are shown in Appendix Fig S7. Circles: bacterial lawns display green fluorescent rings as a function of radial arabinose gradients from central paper discs (white). Images were taken 6 h after addition of arabinose. Figure adapted from Schaerli et al (2014). Yolanda Schaerli et al. Mol Syst Biol 2018;14:e8102 © as stated in the article, figure or figure legend