Figure 3. Expression patterns of cyp26 gene family members in late developing retina are conserved between zebrafish and mouse.

To learn if the divergent subfunction partitioning between zebrafish cyp26a1 and mouse cyp26b1 in gonad development applies to other organs, we studied the expression of cyp26 paralogs during retina development in 15-dpf zebrafish. Results revealed expression of cyp26a1 and cyp26c1 in different layers of the retina, but no detectable expression of cyp26b1 (A: n=1). This result agrees with the Cyp26 expression profile described in mouse retina (B), in which Cyp26a1 and Cyp26c1 genes were expressed in the inner nuclear layer during post-natal eye development while Cyp26b1 was not expressed in the eye [74]. We conclude that independent subfunction partitioning related to gonad development occurred after the teleost-tetrapod lineage divergence, while subfunctions related to at least one other organ, the retina, are still conserved between Cyp26 orthologs in different vertebrate lineages (B).