Editing Melanin (section)

== Other organisms ==
Melanins have very diverse roles and functions in various organisms. A form of melanin makes up the ink used by many [[cephalopod]]s (see [[cephalopod ink]]) as a defense mechanism against predators. Melanins also protect microorganisms, such as bacteria and fungi, against stresses that involve cell damage such as [[UV radiation]] from the sun and [[reactive oxygen species]]. Melanin also protects against damage from high temperatures, chemical stresses (such as [[heavy metals]] and [[oxidizing agents]]), and biochemical threats (such as host defenses against invading microbes).<ref name="Hamilton & Gomez">{{Cite journal |vauthors=Hamilton AJ, Gomez BL |date=March 2002 |title=Melanins in fungal pathogens |journal=Journal of Medical Microbiology |volume=51 |issue=3 |pages=189–91 |doi=10.1099/0022-1317-51-3-189 |pmid=11871612 |doi-access=free}}</ref> Therefore, in many pathogenic microbes (for example, in ''[[Cryptococcus neoformans]]'', a fungus) melanins appear to play important roles in [[virulence]] and [[pathogenicity]] by protecting the microbe against [[immune system|immune]] responses of its [[host (biology)|host]]. In [[invertebrate]]s, a major aspect of the innate immune defense system against invading pathogens involves melanin. Within minutes after infection, the microbe is encapsulated within melanin (melanization), and the generation of [[free radical]] byproducts during the formation of this capsule is thought to aid in killing them.<ref>{{Cite journal |vauthors=Cerenius L, Söderhäll K |date=April 2004 |title=The prophenoloxidase-activating system in invertebrates |journal=Immunological Reviews |volume=198 |pages=116–26 |doi=10.1111/j.0105-2896.2004.00116.x |pmid=15199959 |s2cid=10614298}}</ref> Some types of fungi, called [[radiotrophic fungus|radiotrophic fungi]], appear to be able to use melanin as a [[photosynthetic pigment]] that enables them to capture [[gamma rays]]<ref>{{Cite journal |last=Castelvecchi |first=Davide |date=26 May 2007 |title=Dark Power: Pigment seems to put radiation to good use |journal=Science News |volume=171 |issue=21 |pages=325 |doi=10.1002/scin.2007.5591712106}}</ref> and harness this energy for growth.<ref name="Dadachova et al.">{{Cite journal |vauthors=Dadachova E, Bryan RA, Huang X, etal |year=2007 |title=Ionizing radiation changes the electronic properties of melanin and enhances the growth of melanized fungi |journal=PLOS ONE |volume=2 |issue=5 |pages=e457 |bibcode=2007PLoSO...2..457D |doi=10.1371/journal.pone.0000457 |pmc=1866175 |pmid=17520016 |doi-access=free}}</ref>

In [[fish]], melanin occurs not only in the skin but also in internal organs such as eyes. Most fish species use eumelanin,<ref name="FishChromatophores">{{Cite journal |vauthors=Sköld HN, Aspengren S, Cheney KL, Wallin M |year=2016 |title=Chapter Four - Fish Chromatophores—From Molecular Motors to Animal Behavior |journal=International Review of Cell and Molecular Biology |volume=321 |pages=171–219 |doi=10.1016/bs.ircmb.2015.09.005 |pmid=26811288}}</ref><ref name="eumelanin">{{Cite journal |last1=Kottler |first1=Verena A. |last2=Künstner |first2=Axel |last3=Schartl |first3=Manfred |date=May 2015 |title=Pheomelanin in fish? |url=https://onlinelibrary.wiley.com/doi/10.1111/pcmr.12359 |journal=Pigment Cell & Melanoma Research |language=en |volume=28 |issue=3 |pages=355–356 |doi=10.1111/pcmr.12359 |issn=1755-1471 |pmid=25660115 |s2cid=8877527 |access-date=22 February 2024 |archive-date=22 February 2024 |archive-url=https://web.archive.org/web/20240222235415/https://onlinelibrary.wiley.com/doi/10.1111/pcmr.12359 |url-status=live }}</ref> but ''[[Stegastes apicalis]]'' and ''[[Cyprinus carpio]]'' use pheomelanin instead.<ref name="Xuetal">{{Cite journal |last1=Xu |first1=Peng |last2=Zhang |first2=Xiaofeng |last3=Wang |first3=Xumin |last4=Li |first4=Jiongtang |last5=Liu |first5=Guiming |last6=Kuang |first6=Youyi |last7=Xu |first7=Jian |last8=Zheng |first8=Xianhu |last9=Ren |first9=Lufeng |last10=Wang |first10=Guoliang |last11=Zhang |first11=Yan |last12=Huo |first12=Linhe |last13=Zhao |first13=Zixia |last14=Cao |first14=Dingchen |last15=Lu |first15=Cuiyun |date=November 2014 |title=Genome sequence and genetic diversity of the common carp, Cyprinus carpio |journal=Nature Genetics |language=en |volume=46 |issue=11 |pages=1212–1219 |doi=10.1038/ng.3098 |issn=1061-4036 |pmid=25240282 |doi-access=free}}</ref><ref name="FishInteguments">{{Cite journal |vauthors=Mouchet SR, Cortesi F, Bokic B, Lazovic V, Vukusic P, Marshall NJ, Kolaric B |date=1 November 2023 |title=Morphological and Optical Modification of Melanosomes in Fish Integuments upon Oxidation |journal=Optics |volume=4 |issue=4 |pages=563–562 |doi=10.3390/opt4040041 |doi-access=free}}</ref>

The darker [[feather]]s of birds owe their color to melanin and are less readily degraded by bacteria than unpigmented ones or those containing [[carotenoid]] pigments.<ref>{{Cite journal |last1=Gunderson |first1=Alex R. |last2=Frame |first2=Alicia M. |last3=Swaddle |first3=John P. |last4=Forsyth |first4=Mark H. |date=1 September 2008 |title=Resistance of melanized feathers to bacterial degradation: is it really so black and white? |journal=Journal of Avian Biology |volume=39 |issue=5 |pages=539–545 |doi=10.1111/j.0908-8857.2008.04413.x}}</ref> Feathers that contain melanin are also 39% more resistant to abrasion than those that do not because melanin granules help fill the space between the [[keratin]] strands that form feathers.<ref>{{Cite journal |last=Bonser |first=Richard H. C. |year=1995 |title=Melanin and the Abrasion Resistance of Feathers |url=https://sora.unm.edu/node/105022 |journal=Condor |volume=97 |issue=2 |pages=590–591 |doi=10.2307/1369048 |jstor=1369048 |access-date=25 September 2017 |archive-date=23 January 2020 |archive-url=https://web.archive.org/web/20200123211823/https://sora.unm.edu/node/105022 |url-status=live }}</ref><ref>{{Cite journal |last1=Galván |first1=Ismael |last2=Solano |first2=Francisco |date=8 April 2016 |title=Bird Integumentary Melanins: Biosynthesis, Forms, Function and Evolution |journal=International Journal of Molecular Sciences |volume=17 |issue=4 |page=520 |doi=10.3390/ijms17040520 |pmc=4848976 |pmid=27070583 |doi-access=free}}</ref> Pheomelanin synthesis in birds 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. Indeed, many carnivorous birds, which have a high protein content in their diet, exhibit pheomelanin‐based coloration.<ref>{{Cite journal |last1=Rodríguez-Martínez |first1=Sol |last2=Galván |first2=Ismael |year=2020 |title=Juvenile pheomelanin-based plumage coloration has evolved more frequently in carnivorous species |journal=Ibis |language=en |volume=162 |issue=1 |pages=238–244 |doi=10.1111/ibi.12770 |issn=1474-919X |s2cid=202018215 |hdl-access=free |hdl=10261/207451}}</ref>

Melanin is also important in [[mammal]]ian pigmentation.<ref>{{Cite journal |last1=Jimbow |first1=K |last2=Quevedo WC |first2=Jr |last3=Fitzpatrick |first3=TB |last4=Szabo |first4=G |date=July 1976 |title=Some aspects of melanin biology: 1950–1975 |journal=The Journal of Investigative Dermatology |volume=67 |issue=1 |pages=72–89 |doi=10.1111/1523-1747.ep12512500 |pmid=819593 |doi-access=free}}</ref> The coat pattern of mammals is determined by the [[agouti gene]] which regulates the distribution of melanin.<ref>{{Cite book |last=Meneely |first=Philip |url=https://books.google.com/books?id=8DxdDgAAQBAJ&pg=PA377 |title=Genetic Analysis: Genes, Genomes, and Networks in Eukaryotes |date=2014 |publisher=Oxford University Press |isbn=9780199681266 |access-date=26 August 2020 |archive-date=30 August 2024 |archive-url=https://web.archive.org/web/20240830064614/https://books.google.com/books?id=8DxdDgAAQBAJ&pg=PA377#v=onepage&q&f=false |url-status=live }}</ref><ref>{{Cite journal |last1=Griffiths |first1=Anthony JF |last2=Miller |first2=Jeffrey H. |last3=Suzuki |first3=David T. |last4=Lewontin |first4=Richard C. |last5=Gelbart |first5=William M. |year=2000 |title=Gene interaction in coat color of mammals |url=https://www.ncbi.nlm.nih.gov/books/NBK21804/ |journal=[[NCBI]]}}{{Dead link|date=September 2022|fix-attempted=yes}}</ref> The mechanisms of the gene have been extensively studied in mice to provide an insight into the diversity of mammalian coat patterns.<ref>{{Cite journal |last1=Millar |first1=S. E. |last2=Miller |first2=M. W. |last3=Stevens |first3=M. E. |last4=Barsh |first4=G. S. |date=October 1995 |title=Expression and transgenic studies of the mouse agouti gene provide insight into the mechanisms by which mammalian coat color patterns are generated |journal=Development |volume=121 |issue=10 |pages=3223–3232 |doi=10.1242/dev.121.10.3223 |pmid=7588057}}</ref>

Melanin in [[arthropods]] has been observed to be deposited in layers thus producing a [[Bragg reflector]] of alternating refractive index. When the scale of this pattern matches the wavelength of visible light, [[structural coloration]] arises: giving a number of species an [[iridescent]] color.<ref>{{Cite book |last=Neville |first=A. C. |url=https://books.google.com/books?id=VQHtCAAAQBAJ&pg=PA121 |title=Biology of the Arthropod Cuticle |date=2012 |publisher=Springer Science & Business Media |isbn=9783642809101 |access-date=26 August 2020 |archive-date=30 August 2024 |archive-url=https://web.archive.org/web/20240830064614/https://books.google.com/books?id=VQHtCAAAQBAJ&pg=PA121#v=onepage&q&f=false |url-status=live }}</ref><ref name="Mouchet2021">{{Citation |last1=Mouchet |first1=Sébastien R |title=Natural Photonics and Bioinspiration |year=2021 |url=https://us.artechhouse.com/Natural-Photonics-and-Bioinspiration-P2221.aspx |edition=1st |publisher=Artech House |isbn=978-163-081-797-8 |last2=Deparis |first2=Olivier |access-date=7 November 2023 |archive-date=12 November 2023 |archive-url=https://web.archive.org/web/20231112212527/https://us.artechhouse.com/Natural-Photonics-and-Bioinspiration-P2221.aspx |url-status=live }}</ref>

[[Arachnid]]s are one of the few groups in which melanin has not been easily detected, though researchers found data suggesting spiders do in fact produce melanin.<ref name="HsiungBlackledge2015">{{Cite journal |last1=Hsiung |first1=B.-K. |last2=Blackledge |first2=T. A. |last3=Shawkey |first3=M. D. |year=2015 |title=Spiders do have melanin after all |journal=Journal of Experimental Biology |volume=218 |issue=22 |pages=3632–3635 |doi=10.1242/jeb.128801 |pmid=26449977 |doi-access=free}}</ref>

Some moth species, including the [[Parasemia plantaginis|wood tiger moth]], convert resources to melanin to enhance their thermoregulation. As the wood tiger moth has populations over a large range of latitudes, it has been observed that more northern populations showed higher rates of melanization. In both yellow and white male phenotypes of the wood tiger moth, individuals with more melanin had a heightened ability to trap heat but an increased predation rate due to a weaker and less effective [[Aposematism|aposematic]] signal.<ref>{{Cite journal |last1=Hegna |first1=Robert H. |last2=Nokelainen |first2=Ossi |last3=Hegna |first3=Jonathan R. |last4=Mappes |first4=Johanna |year=2013 |title=To quiver or to shiver: increased melanization benefits thermoregulation, but reduces warning signal efficacy in the wood tiger moth |journal=Proc. R. Soc. B |volume=280 |issue=1755 |pages=20122812 |doi=10.1098/rspb.2012.2812 |pmc=3574392 |pmid=23363631}}</ref>

Melanin may protect ''[[Drosophila]]'' flies and [[laboratory mouse|mice]] against DNA damage from non-UV radiation.<ref name="Mosse-et-al-2001">{{Cite conference |last1=Mosse |first1=Irma B. |last2=Dubovic |first2=Boris V. |last3=Plotnikova |first3=Svetlana I. |last4=Kostrova |first4=Ludmila N. |last5=Molophei |first5=Vadim |last6=Subbot |first6=Svetlana T. |last7=Maksimenya |first7=Inna P. |date=20-25 May 2001 |editor-last=Obelic |editor-first=B. |editor2-last=Ranogajev-Komor |editor2-first=M. |editor3-last=Miljanic |editor3-first=S. |editor4-last=Krajcar Bronic |editor4-first=I. |title=Melanin is Effective Radioprotector against Chronic Irradiation and Low Radiation Doses |conference=IRPA Regional Congress on Radiation Protection in Central Europe: Radiation Protection and Health |location=[[Dubrovnik]] (Croatia) |publisher=[[Croatian Radiation Protection Association]] |page=35 (of 268) |website=INIS}}</ref>

=== Plants ===
[[File:Indol-5,6-chinon.svg|thumb|Chemical structure of indole-5,6-quinone]]
Melanin produced by plants are sometimes referred to as 'catechol melanins' as they can yield [[catechol]] on alkali fusion. It is commonly seen in the [[enzymatic browning]] of fruits such as bananas. Chestnut shell melanin can be used as an antioxidant and coloring agent.<ref>{{Cite journal |last1=Yao |first1=Zeng-Yu |last2=Qi |first2=Jian-Hua |date=22 April 2016 |title=Comparison of Antioxidant Activities of Melanin Fractions from Chestnut Shell |journal=Molecules |volume=21 |issue=4 |pages=487 |doi=10.3390/molecules21040487 |pmc=6273334 |pmid=27110763 |doi-access=free}}</ref> Biosynthesis involves the oxidation of [[indole-5,6-quinone]] by the tyrosinase type [[polyphenol oxidase]] from [[tyrosine]] and [[catecholamines]] leading to the formation of catechol melanin. Despite this many plants contain compounds which inhibit the production of melanins.<ref>{{Cite journal |last1=Kim |first1=Y.-J. |last2=Uyama |first2=H. |date=15 May 2005 |title=Tyrosinase inhibitors from natural and synthetic sources: structure, inhibition mechanism and perspective for the future |journal=Cellular and Molecular Life Sciences |volume=62 |issue=15 |pages=1707–1723 |doi=10.1007/s00018-005-5054-y |pmc=11139184 |pmid=15968468 |s2cid=8280251}}</ref>