Fig. 6
From: Variable levels of drift in tunicate cardiopharyngeal gene regulatory elements
Functional constraint on binding site spacing in the C. robusta FoxF TVC enhancer. a The first Ets1/2-binding site was moved by knocking out the endogenous binding site (GGAT ⟶ GCTT) and introducing a new binding site using site-directed mutagenesis. Reporter constructs contained the 245 bp minimal C. robusta FoxF TVC enhancer fused to the C. robusta Fkh basal promoter (Cirobu.FoxF −1072/−827::pFkh). The sequence of the enhancer region containing this first Ets1/2-binding site is shown on the left with Ets1/2 (red) and ATTA (blue)-binding sites highlighted. The graph depicts %TVC expression in C. robusta (number of trials ≥ 2, total N ≥ 75, and error bars indicate standard deviation). b–d Representative C. robusta embryos showing reporter expression for b Corobu.FoxF −1072/−827::pFkh, c Corobu.FoxF −1072/−827::pFkh ∆E1, or d Corobu.FoxF −1072/−827::pFkh Move 1. Arrows point to normal position of TVCs in the trunk region. Note substantial ectopic expression in the anterior tail muscle lineage (ATM) and in other muscle and mesenchyme lineage cells