Figure 3. Identifying minimal promoters that are functional in lamprey.

(A–B) Lateral (A) and dorsal (B) views of stage 26 transient transgenic lamprey embryos, showing reporter expression in the anterior hindbrain driven by different minimal promoters in conjunction with the pm3299 enhancer using the I-SceI meganuclease approach. (C) Lateral views of stage 23 lamprey embryos injected with the same constructs as those in A and B, showing early expression in ectoderm and yolk, similar to the background expression driven by the control cfos_I-SceI_EGFP construct (see Figure 1I). The identity of the minimal promoter used in each case is indicated above the top panel. Abbreviations: ec, ectoderm; hb, hindbrain; ph, pharynx; y, yolk.