title: Developmentally Regulated Production of meso-Zeaxanthin in Chicken Retinal Pigment Epithelium/Choroid and Retina.
abstract: OBJECTIVE
  meso-Zeaxanthin is a carotenoid that is rarely encountered in nature outside of the vertebrate eye. It is not a constituent of a normal human diet, yet this carotenoid comprises one-third of the primate macular pigment. In the current study, we undertook a systematic approach to biochemically characterize the production of meso-zeaxanthin in the vertebrate eye.
  
  
  METHODS
  Fertilized White Leghorn chicken eggs were analyzed for the presence of carotenoids during development. Yolk, liver, brain, serum, retina, and RPE/choroid were isolated, and carotenoids were extracted. The samples were analyzed on C-30 or chiral HPLC columns to determine the carotenoid composition.
  
  
  RESULTS
  Lutein and zeaxanthin were found in all studied nonocular tissues, but no meso-zeaxanthin was ever detected. Among the ocular tissues, the presence of meso-zeaxanthin was consistently observed starting at embryonic day 17 (E17) in the RPE/choroid, several days before its consistent detection in the retina. If RPE/choroid of an embryo was devoid of meso-zeaxanthin, the corresponding retina was always negative as well.
  
  
  CONCLUSIONS
  This is the first report of developmentally regulated synthesis of meso-zeaxanthin in a vertebrate system. Our observations suggest that the RPE/choroid is the primary site of meso-zeaxanthin synthesis. Identification of meso-zeaxanthin isomerase enzyme in the developing chicken embryo will facilitate our ability to determine the biochemical mechanisms responsible for production of this unique carotenoid in other higher vertebrates, such as humans.
authors.forename: Aruna
authors.initials: A
authors.lastname: Gorusupudi
authors.forename: Rajalekshmy
authors.initials: R
authors.lastname: Shyam
authors.forename: Binxing
authors.initials: B
authors.lastname: Li
authors.forename: Preejith
authors.initials: P
authors.lastname: Vachali
authors.forename: Yumna K
authors.initials: YK
authors.lastname: Subhani
authors.forename: Kelly
authors.initials: K
authors.lastname: Nelson
authors.forename: Paul S
authors.initials: PS
authors.lastname: Bernstein
mesh_terms: D000818:Animals; D002642:Chick Embryo; D002829:Choroid / Q000196:embryology / Q000378:metabolism*; D002851:Chromatography, High Pressure Liquid; D055213:Retinal Pigment Epithelium / Q000196:embryology / Q000378:metabolism*; D065146:Zeaxanthins / Q000096:biosynthesis
chemical_list: D065146:Zeaxanthins; C584722:meso-zeaxanthin