(A) The non-coding regions around the D. melanogaster bond locus were screened for enhancer activity that is able to drive GFP reporter protein expression in the EB. One fragment (black line), the first intron, was able to drive GFP expression in the EB. The other fragments (gray lines) did not drive EB expression.
(B) Intron 1 of bond from D. melanogaster, D. simulans, D. yakuba, D. erecta, D. ananassae, and S. lebanonensis drove GFP expression in the EB swe. Homologous fragments from D. willistoni, D. virilis, and M. domestica did not. Scale bar, 100 μm.