title: Genetic Basis for Red Coloration in Birds.
abstract: The yellow and red feather pigmentation of many bird species [1] plays pivotal roles in social signaling and mate choice [2, 3]. To produce red pigments, birds ingest yellow carotenoids and endogenously convert them into red ketocarotenoids via an oxidation reaction catalyzed by a previously unknown ketolase [4-6]. We investigated the genetic basis for red coloration in birds using whole-genome sequencing of red siskins (Spinus cucullata), common canaries (Serinus canaria), and "red factor" canaries, which are the hybrid product of crossing red siskins with common canaries [7]. We identified two genomic regions introgressed from red siskins into red factor canaries that are required for red coloration. One of these regions contains a gene encoding a cytochrome P450 enzyme, CYP2J19. Transcriptome analysis demonstrates that CYP2J19 is significantly upregulated in the skin and liver of red factor canaries, strongly implicating CYP2J19 as the ketolase that mediates red coloration in birds. Interestingly, a second introgressed region required for red feathers resides within the epidermal differentiation complex, a cluster of genes involved in development of the integument. Lastly, we present evidence that CYP2J19 is involved in ketocarotenoid formation in the retina. The discovery of the carotenoid ketolase has important implications for understanding sensory function and signaling mediated by carotenoid pigmentation.
authors.affiliation: CIBIO/InBIO, Centro de Investigação em Biodiversidade e Recursos Genéticos, Campus Agrário de Vairão, Universidade do Porto, 4485-661 Vairão, Portugal.
authors.forename: Ricardo J
authors.initials: RJ
authors.lastname: Lopes
authors.affiliation: Department of Biological Sciences, Auburn University, Auburn, AL 36849, USA.
authors.forename: James D
authors.initials: JD
authors.lastname: Johnson
authors.affiliation: Department of Pathology and Immunology, Washington University School of Medicine, St. Louis, MO 63110, USA.
authors.forename: Matthew B
authors.initials: MB
authors.lastname: Toomey
authors.affiliation: CIBIO/InBIO, Centro de Investigação em Biodiversidade e Recursos Genéticos, Campus Agrário de Vairão, Universidade do Porto, 4485-661 Vairão, Portugal.
authors.forename: Mafalda S
authors.initials: MS
authors.lastname: Ferreira
authors.affiliation: CIBIO/InBIO, Centro de Investigação em Biodiversidade e Recursos Genéticos, Campus Agrário de Vairão, Universidade do Porto, 4485-661 Vairão, Portugal; Marine and Environmental Sciences Centre (MARE), Department of Life Sciences, University of Coimbra, 3004-517 Coimbra, Portugal.
authors.forename: Pedro M
authors.initials: PM
authors.lastname: Araujo
authors.affiliation: CIBIO/InBIO, Centro de Investigação em Biodiversidade e Recursos Genéticos, Campus Agrário de Vairão, Universidade do Porto, 4485-661 Vairão, Portugal; Departamento de Biologia, Faculdade de Ciências, Universidade do Porto, Rua do Campo Alegre s⁄n., 4169-007 Porto, Portugal.
authors.forename: José
authors.initials: J
authors.lastname: Melo-Ferreira
authors.affiliation: Science of Life Laboratory Uppsala, Department of Medical Biochemistry and Microbiology, Uppsala University, 75123 Uppsala, Sweden; Department of Animal Breeding and Genetics, Swedish University of Agricultural Sciences, 75007 Uppsala, Sweden; Department of Veterinary Integrative Biosciences, College of Veterinary Medicine and Biomedical Sciences, Texas A&M University, College Station, TX 77845, USA.
authors.forename: Leif
authors.initials: L
authors.lastname: Andersson
authors.affiliation: Department of Biological Sciences, Auburn University, Auburn, AL 36849, USA. Electronic address: hillgee@auburn.edu.
authors.forename: Geoffrey E
authors.initials: GE
authors.lastname: Hill
authors.affiliation: Department of Pathology and Immunology, Washington University School of Medicine, St. Louis, MO 63110, USA. Electronic address: jcorbo@pathology.wustl.edu.
authors.forename: Joseph C
authors.initials: JC
authors.lastname: Corbo
authors.affiliation: CIBIO/InBIO, Centro de Investigação em Biodiversidade e Recursos Genéticos, Campus Agrário de Vairão, Universidade do Porto, 4485-661 Vairão, Portugal; Departamento de Biologia, Faculdade de Ciências, Universidade do Porto, Rua do Campo Alegre s⁄n., 4169-007 Porto, Portugal. Electronic address: miguel.carneiro@cibio.up.pt.
authors.forename: Miguel
authors.initials: M
authors.lastname: Carneiro
mesh_terms: D000818:Animals; D030161:Avian Proteins / Q000235:genetics* / Q000378:metabolism; D002171:Canaries / Q000235:genetics / Q000254:growth & development / Q000502:physiology; D003577:Cytochrome P-450 Enzyme System / Q000235:genetics* / Q000378:metabolism; D005241:Feathers / Q000254:growth & development / Q000502:physiology*; D046369:Finches / Q000235:genetics / Q000254:growth & development / Q000502:physiology*; D008099:Liver / Q000502:physiology; D010858:Pigmentation; D010860:Pigments, Biological / Q000235:genetics* / Q000378:metabolism; D012160:Retina / Q000502:physiology; D012879:Skin Physiological Phenomena
chemical_list: D030161:Avian Proteins; D010860:Pigments, Biological; D003577:Cytochrome P-450 Enzyme System