Melanin Chemistry and the Ecology of Stress

Abstract

JSTOR is a not-for-profit service that helps scholars, researchers, and students discover, use, and build upon a wide range of content in a trusted digital archive. We use information technology and tools to increase productivity and facilitate new forms of scholarship. For more information about JSTOR, please contact support@jstor.org. ABSTRACTKnowledge of melanin chemistry has important implications for the study of the evolutionary ecology of animal pigmentation, but the actual chemical diversity of these widely expressed biological pigments has been largely overlooked. Considering all melanin forms and the different conditions of endogenous oxidative stress during their synthesis provides information about physiological costs and benefits of different pigmentation patterns and opens a new perspective to understanding the evolution of color phenotypes in animals.

Raman spectroscopy quantification of eumelanin subunits in natural unaltered pigments

“…This process is therefore potentially cytotoxic. This cytotoxicity depends on the relative amount of the two o ‐diphenols that are synthesized, and then eumelanins differing in the content of o ‐diphenols may also differ in the potential to damage cells (Galván & Solano, ). Analytical methods for a straightforward, direct determination of the content of o ‐diphenols in eumelanins would therefore be of high relevance to biology, but such methods are currently unavailable (d’Ischia et al., ).…”

Plumage colour and the expression of stress‐related genes in gull chicks

“…Chicks that better cope with physiological stress could afford the physiological costs of melanisation (e.g. oxidative stress), thus reflecting their physiological machinery (Galván and Solano , 2016). We cannot discard the possibility that the functional properties of melanins may also provide to chicks more resistance against UV radiation and overheating (Dreiss et al ).…”

“…Melanins play an important role for protection against UV radiation (Hansson et al , Brenner and Hearing ) and predator avoidance by providing organisms cryptic or aposematic coloration (Chaniot , Kilner ). The synthesis of melanins (melanogenesis) may be affected by diverse physiological and environmental conditions (Griffith et al , Roulin et al , Galván and Solano ), but it is mainly genetically regulated by the melanocortin system (Ducrest et al ). Briefly, the melanocortins produced by the proopiomelanocortin (POMC) gene bind to the melanocortin receptor 1 (MCR1) inducing the synthesis of melanins; however, the union of melanocortins with the other four melanocortin receptors (MCR2‐MCR5) regulates other important physiological functions such as stress response, exocrine gland activity and immune response (Ducrest et al ).…”

“…Melanins play an important role for protection against UV radiation (Hansson et al 2007, Brenner andHearing 2008) and predator avoidance by providing organisms cryptic or aposematic coloration (Chaniot 1970, Kilner 2006. The synthesis of melanins (melanogenesis) may be affected by diverse physiological and environmental conditions (Griffith et al 1999, Galván and Solano 2015, but it is mainly genetically regulated by the melanocortin system (Ducrest et al 2008).…”

A dark cuticle allows higher investment in immunity, longevity and fecundity in a beetle upon a simulated parasite attack

“…This substance has been shown to be involved in a wide range of vital adaptive functions as diverse as camouflage (Kettlewell 1973;Hoekstra et al 2006), photoprotection (Ortonne 2002), sexual signaling (Jawor and Breitwisch 2003;Svensson and Waller 2013), thermoregulation (Vences et al 2002), protection against reactive oxygen species (Galván and Solano 2015) and strengthening insect cuticles (Riley 1997). The role of melanin pigmentation has also been demonstrated in immune defense (Wilson et al 2001;Männiste andHõrak 2014, but see Contreras-Garduño et al 2007).…”