TY - JOUR
T1 - Comparisons of the structural and chemical properties of melanosomes isolated from retinal pigment epithelium, iris and choroid of newborn and mature bovine eyes
AU - Liu, Yan
AU - Hong, Lian
AU - Wakamatsu, Kazumasa
AU - Ito, Shosuke
AU - Adhyaru, Bhavin B.
AU - Cheng, Chi Yuan
AU - Bowers, Clifford R.
AU - Simon, John D.
PY - 2005/5
Y1 - 2005/5
N2 - 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. 13C 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 13C 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.
AB - 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. 13C 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 13C 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.
UR - http://www.scopus.com/inward/record.url?scp=21244431610&partnerID=8YFLogxK
UR - http://www.scopus.com/inward/citedby.url?scp=21244431610&partnerID=8YFLogxK
U2 - 10.1562/2004-10-19-RA-345.1
DO - 10.1562/2004-10-19-RA-345.1
M3 - Article
C2 - 15701042
AN - SCOPUS:21244431610
SN - 0031-8655
VL - 81
SP - 510
EP - 516
JO - Photochemistry and photobiology
JF - Photochemistry and photobiology
IS - 3
ER -