(A) Embryo electroporated with the Lama enhancer (ZEE13); GFP expression can be seen in the notochord.
(B) Embryo electroporated with Lama -E3, where ETS3 was mutated to be non-functional; no GFP expression detected.
(C) Embryo electroporated with Lama -Z, where the Zic was mutated to be non-functional; no GFP expression detected.
(D) Embryo electroporated with Lama RE3, where the sequence of ETS3 was reversed; no GFP expression detected. Comparable results were seen when ETS1 was reversed.
In (A)–(D), for each enhancer, three biological replicates were performed with 50 embryos per replicate (see Table S4). Each image in this figure is representative of the expression observed from three biological replicates. Scale bars, 50μm.
(E) Schematics of Zic and ETS clusters near laminin alpha in the genome of Ciona, mouse, and human. All three laminin alpha clusters have a spacing of 12 bp between an ETS and Zic site and all contain non-consensus ETS sites. ETS site affinity scores are noted above each site. Dark blue ETS sites have an affinity of greater than 0.5, light blue sites have an affinity of less than 0.5.