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Comparisons of the Structural and Chemical Properties of Melanosomes Isolated from Retinal Pigment Epithelium, Iris and Choroid of Newborn and Mature Bovine Eyes ¶
Author(s) -
Liu Yan,
Hong Lian,
Wakamatsu Kazumasa,
Ito Shosuke,
Adhyaru Bhavin B.,
Cheng ChlYuan,
Bowers Clifford R.,
Simon John D.
Publication year - 2005
Publication title -
photochemistry and photobiology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.818
H-Index - 131
eISSN - 1751-1097
pISSN - 0031-8655
DOI - 10.1111/j.1751-1097.2005.tb00218.x
Subject(s) - melanosome , choroid , iris (biosensor) , melanin , retinal pigment epithelium , retinal , chemistry , biology , biochemistry , retina , computer security , neuroscience , computer science , biometrics
ABSTRACT Melanosomes were isolated from the retinal pigment epithelium (RPE), iris and choroid of mature (age >2 years) and newborn (age <1 week) bovine eyes. Scanning electron microscopy was utilized to analyze the morphology of the melanosomes, which were found to vary among different tissues and different ages. While the total content of amino acids differs slightly (ranging from 9% to 15% by mass), the distributions of the amino acids are similar. The pheomelanin content is low in the choroid and the RPE (0.1–0.5%), and moderate in the iris (<2%); therefore, the major melanin component of bovine eye melanosomes is eumelanin, independent of the shape of the melanosomes. The yields of pyrrole‐2,3,5‐tricarboxylic acid from melanosomes decrease in the following order: choroid > iris > RPE, and exhibit decreasing yields with age. 13 C solid‐state nuclear magnetic resonance (NMR) spectroscopic analysis of iris and choroid melanosomes indicates the same trends. These observations suggest that the 5,6‐dihydroxyindole‐2‐carboxylic acid contents decrease in the following order: choroid > iris > RPE, and decrease with age. Moreover, the 13 C solid‐state NMR spectra show (1) for the same age samples, the CH:Cq ratio for choroid is larger than that for iris melanosomes; and (2) an increase in the concentration of carbonyl groups with age within each type of melanosome.