3 [micro]m) and ellipsoidal with a highly ordered glycoprotein matrix that is integral to the production of the black or brown coloured eumelanin pigments, whereas the red or yellow pheomelanins are produced within smaller and spherical (~0.
Pale yellow aqueous layers containing pheomelanins were cleared by centrifugation at 10 700 g for 10 min and analyzed for absorbance at 400 nm.
Though the phenotypes of eumelanin and pheomelanin of alpaca were not identified, the phenotype of the alkali-soluble melanin (including pheomelanins and eumelanins) can represent grossly the color of hair (Figure 2).
The contents of the pheomelanins in different hair colors were very low, and had no relationship to the alpaca hair color.
The results also showed that eumelanins and pheomelanins existed in small quantities in white alpaca hair.
Sepia melanin was purchased from Sigma and used as a standard for spectrophotometric assay of total melanin, eumelanin and pheomelanin.
In a previous study on contents of eumelanin and pheomelanin in some species such as humans and mice, the methods were based on measuring the pyrrole-2,3,5-tricarboxylic acid (PTCA, the chemical degradation of eumelanin) and aminohydroxyphenylalanine isomers (AHP, the chemical degradation of pheomelanin) by HPLC (Ito et al.
We did not study the pigments responsible for plumage coloration, but it is likely the rufous rump and underparts of Tawny-bellied Seedeaters, and the black head, black pectoral band, and cinnamon rump and underparts of Rusty-collared Seedeaters are produced by eumelanins and pheomelanins
117-121) Eumelanin is characterized by the presence of paramagnetic centers that are solely of the semiquinone type, while pheomelanin contains a hyperfine structure with an unpaired electron near the nucleus of [sup.
In pheomelanogenesis, vesiculoglobular bodies are incorporated into stage I melanosomes, while at stage II melanosome pheomelanin is deposited in the vesiculoglobular bodies.