The accumulation of the amino acid cysteine in lysosomes produces toxic substances, which are avoided by a gene (CTNS) coding for a transporter that pumps cystine out of lysosomes. Melanosomes are lysosome-related organelles that synthesize melanins, the most widespread pigments in animals. The synthesis of the orange melanin, termed pheomelanin, depends on cysteine levels because the sulfhydryl group is used to form the pigment. Pheomelanin synthesis may, therefore, be affected by cysteine...

The colors of primates are among the most diverse phenotypes in mammals. These colors are mostly produced by the deposition of melanin pigments in hairs. Many species show considerable variability in pigmentation, but this is always temporarily fixed. Here the first rapid change in the pigmentation phenotype of a primate is reported. In the last five years, the pelage of mantled howler monkeys Alouatta palliata inhabiting Costa Rica has started to change from fully black to yellowish,...

Eumelanins are large polymers composed of 5,6-dihydroxyindole (DHI) and 5,6-dihydroxyindole-2-carboxylic acid (DHICA). ROS generation is higher during the synthesis of DHI than during the synthesis of DHICA, thus the production of eumelanins with high relative DHI contents may compromise the viability of cells and organisms. Here it is shown that dispersive Raman spectroscopy allows a non-invasive direct detection and quantification of DHI and DHICA in unaltered eumelanins that can be applied...

The appearance of animals largely depends on melanins present in their integument. However, it is unclear how different melanin forms create different animal color phenotypes. Reflectance spectrophotometry was used to measure the color expression of feathers and hairs of 59 species of birds and 12 species of mammals, comprising a significant part of the palette of melanin-based colors, and analyzed for the first time the detailed chemical composition of melanins on the same samples by HPLC.

Melanins are the ubiquitous pigments distributed in nature. They are one of the main pigments responsible for colors in living cells. Birds are among the most diverse animals regarding melanin-based coloration, especially in the plumage, although they also pigment bare parts of the integument. This review is devoted to the main characteristics of bird melanins.