Pheomelanin, the sulfurated form of melanin pigment, is known to produce reactive oxygen species (ROS) and oxidative stress-mediated cytotoxicity. Previous studies have shown a conversion of the benzothiazine moiety of pheomelanin to the benzothiazole moiety under heat or energetic radiation exposure, but it is unknown whether endogenous conditions can also produce this structural change.

The expression of the gene Slc7a11 promotes the antioxidant capacity of cells by providing them with cysteine that can be used for the synthesis of glutathione (GSH), the most important intracellular antioxidant. In melanocytes, intracellular cysteine can also enter melanosomes and get incorporated in the pigment pheomelanin synthesis pathway, thus decreasing cysteine availability for GSH synthesis and potentially creating chronic oxidative stress. Therefore, this study hypothesized that a...

Distinctive pheomelanin-based plumage colouration in juvenile birds has been proposed as a signal of immaturity to avoid aggression by older conspecifics, but recent findings suggest a detoxifying strategy. Pheomelanin synthesis implies the consumption of cysteine, a semi-essential amino acid that is necessary for the synthesis of the antioxidant glutathione (GSH) but that may be toxic if in excess in the diet.

Competitive environments promote high testosterone levels, oxidative stress and, consequently, impair cellular homeostasis. The regulation of genes involved in the synthesis of the pigment pheomelanin in melanocytes seems to help to maintain homeostasis against environmental oxidative stress. Here, social interactions in some zebra finch Taeniopygia guttata males were experimentally increased by keeping them in groups of six birds during feather growth, while others were kept alone, to test...

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,...