Melanin: the emergence of a multifunctional pigment across organismal evolution

The goal of this meeting is to examine the biopigment melanin from its physical properties to its ecological relevance and across distinct organisms such as bacteria, vertebrates, fungi, and plants. Melanins are a family of dark, chemically heterogeneous pigments that provide photoprotection, camouflage and various forms of visual signalling: from pigmentation to structural coloration in birds, insects and other animals. Melanin is also used in species interactions: cephalopods secrete melanin to escape predators, microbes use melanin to evade the host’s immune system, and insects use melanin to encapsulate their pathogens. Melanin is found in almost every organ and plays key roles in homeostasis, metal chelation, and radical scavenging. Melanin is also present in the brain (substantia nigra) and is thought to be involved in brain degeneration (Parkinson’s disease). Its role in human melanoma is still poorly understood. From an evolutionary standpoint, we don’t quite understand the link between animal domestication and loss of coat pigmentation. 

At the molecular level, melanins are the oxidation products of tyrosine and other phenolic precursors; these undergo oxidative polymerisation to form chemically ill-defined “polymers” that are insoluble, lack structural order and lack distinct spectral features, therefore resisting most chemical characterisation tools. 

It is unclear whether melanins have originated multiple times independently (convergent evolution) or they share a common ancestor. The use of distinct enzymes, and biochemical pathways in distinct lineages for melanin production is still poorly mapped on a phylogeny. Equally poorly understood are the gene-regulatory networks coding for these enzymes, that need to be activated in melanin-producing cells at the same time during development. In bacterial and fungi walls, or insect chitin, melanin is deposited in a diffuse form outside the cell membrane, but in vertebrates it is aggregated in clusters or granules inside specialized cell vesicles, such as melanosomes. It is unclear how the structural organization of this polymer in different organisms influences its function. 

Finally, melanin is currently being investigated as a functional material for applications in solar-thermal conversion, as well as space travel and radiation protection. Melanin mimics are being developed for applications ranging from photodynamic therapy to coatings. Given the importance of this multifaceted biopolymer, and its ubiquitous presence across the tree of life, we hope to engage in multidisciplinary and cross-cutting discussions about its origins, chemical structure, function and evolution.

Several researchers at OIST are working on topics that intersect the main theme of this workshop. Some are working on cephalopods that use melanin for evasive tactics but might also have an equivalent region in their brain that is grey and melanin producing (substatia nigra). Others are organic chemists that collaborate with one of the external co-organizers of this workshop (Micaela Matta). Still others work on pattern formation and pigmentation (in insects, flowers, and fish) and will be interested in joining this workshop. The workshop will promote interdisciplinarity thinking and will promote the international visibility of OIST. We will also host international companies and start-ups that have an interest in melanin that may be interested in joining our workshop and/or establish collaborations with academics.

At the conclusion of the workshop, we plan to write a meeting report for publication.

*OIST members are welcome to attend all scientific sessions. Meals are closed sessions for registered participants only.

Workshop website: https://www.oist.jp/conference/melanin-emergence-multifunctional-pigment-across-organismal-evolution

OIST is deeply committed to the advancement of women in science, in Japan and worldwide. Women are strongly encouraged to apply.