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Fig. 9. Summary of reciprocal cross-species transient expression assays using the
Endo16 promoter. Microinjection of the Endo16 promoter into
eggs of the same species results in a pattern of GFP expression (green) that
recapitulates the results of in situ hybridization (A,D). Microinjection of
LvEndo16-GFP into S. purpuratus eggs results in a
host-specific pattern of GFP expression (B), while microinjection of
SpEndo16-GFP into L. variegatus eggs results in a
donor-specific pattern of GFP expression with ectopic fluorescence in the SMCs
and their pigment cell derivatives (C). These data indicate that evolutionary
changes have arisen both cis and trans to the Endo16 gene. (Arrows
indicate hindgut. Arrowheads indicate ectopic fluorescence in the SMCs and
pigment cells.)