Ketocarotenoids Are Absent in the Beak of yellowbeak Birds Yellowbeak Maps to a Narrow Region of Chromosome 8 Containing Candidate Ketolase Genes Yellowbeak Is Associated with a Deletion of a CYP2J2-like Locus CYP2J19 Loci Are Specifically Expressed in Ketocarotenoid-Containing Tissues, and Bill Expression Is Greatly Reduced in yellowbeak In wild-type birds, we detected expression of CYP2J19 loci in the beak, tarsus, and retina, which are all sites of ketocarotenoid deposition, but not in the...
