Evolutionary and biomedical consequences of internal melanins

Dubey, Sylvain; Roulin, Alexandre

doi:10.1111/pcmr.12231

Cited by 68 publications

(58 citation statements)

References 145 publications

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“…The analysis of these pigments indicates the main metabolic activities by macrophages (Leknes, 2015). Melanin can neutralize free radicals (Agius, Roberts, 2003) and other toxic agents derived from the degradation of phagocytized cellular material (Hartley et al, 1996;Dubey, Roulin, 2014). This pigment is also important in the production of antibacterial compounds, especially hydrogen peroxide (Wolke, 1992).…”

Section: Discussionmentioning

confidence: 99%

Comparative histology in the liver and spleen of three species of freshwater teleost

et al. 2017

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We describe and compare the histology of liver and spleen of Geophagus brasiliensis (Perciformes), Hypostomus francisci (Siluriformes) and Hoplias aff. malabaricus (Characiformes), tropical freshwater fishes. In G. brasiliensis and H. aff. malabaricus the hepatocytes were arranged in tubular form whereas in H. francisci they cord-like. In all species, hepatocytes presented glycogen, but in G. brasiliensis and H. aff. malabaricus they showed strong stained for hemossiderin in the cytoplasm. In G. brasiliensis and H. aff. malabaricus, melanomacrophage centres (MMCs) were associated to hepatic structures and only in G. brasiliensis was observed intrahepatic exocrine pancreas. The spleen, in all species, was characterized by red and white pulp without boundary between the two regions, but only in H. francisci was recorded nodular organization in splenic parenchyma. The G. brasiliensis and H. aff. malabaricus presented in the white pulp MMCs linked mainly to ellipsoids. Besides, we observed large MMCs in the spleen in relation to liver of G. brasiliensis and H. aff. malabaricus. In liver, highest values of reticular fibers and collagen were observed in G. brasiliensis. In spleen, highest values of reticular fibers and collagen were recorded in H. aff. malabaricus and H. francisci, respectively. Histological differences confirm the hypothesis that the phylogenetic distance is reflected in liver and spleen.Keywords: Extracellular matrix, Hepatocytes, Intrahepatic exocrine pancreas, Melanomacrophage centres, Red and White pulp.Nós descrevemos e comparamos a histologia do fígado e do baço de Geophagus brasiliensis (Perciformes), Hypostomus francisci (Siluriformes) e Hoplias aff. malabaricus (Characiformes), peixes neotropicais de água doce. Em G. brasiliensis e H. aff. malabaricus os hepatócitos organizaram-se na forma tubular enquanto que em H. francisci eles apresentaram-se como cordões celulares. Em todas as espécies, os hepatócitos apresentaram glicogênio, mas em G. brasiliensis e H. aff. malabaricus, eles mostraram forte marcação para hemossiderina no citoplasma. Em G. brasiliensis e H. aff. malabaricus, centros melanomacrofágicos (CMMs) foram associados a estruturas hepáticas e somente em G. brasiliensis foi observado pâncreas exócrino intrahepático. O baço, em todas as espécies, foi caracterizado pela polpa vermelha e branca sem limites entre as duas regiões, mas somente em H. francisci foi registrado uma organização nodular no parênquima esplênico. G. brasiliensis e H. aff. malabaricus apresentaram na polpa branca CMMs associados principalmente a elipsoides. Além disso, nós observamos CMMs grandes no baço em relação ao fígado de G. brasiliensis e de H. aff. malabaricus. No fígado, valores altos de fibras reticulares e colágeno foram observado em G. brasiliensis. No baço, valores altos de fibras reticulares e colágeno foram registrados em H. aff. malabaricus e H. francisci, respectivamente. Diferenças histológicas confirmam a hipótese que a distância filogenética está refletida no fígado e no baço. Palavras-chave:...

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Section: Discussionmentioning

confidence: 99%

Comparative histology in the liver and spleen of three species of freshwater teleost

et al. 2017

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“…Feather melanism is also associated with ecological benefits, and thus may co‐vary with environmental conditions. Melanin absorbs more broad‐spectrum solar radiation than other colour pigments (Burtt ), including damaging UV‐B radiation (Burtt , Dubey and Roulin ). Feather melanism may directly protect sensitive internal organs by reducing UV penetration to the skin (Burtt , Ward et al ), but may also indicate elevated organ tissue melanism and thus greater UV protection (Dubey and Roulin , but see Galván et al ).…”

Section: Alternative Predictions For Variation In Feather Traits (Plumentioning

confidence: 99%

“…Melanin absorbs more broad‐spectrum solar radiation than other colour pigments (Burtt ), including damaging UV‐B radiation (Burtt , Dubey and Roulin ). Feather melanism may directly protect sensitive internal organs by reducing UV penetration to the skin (Burtt , Ward et al ), but may also indicate elevated organ tissue melanism and thus greater UV protection (Dubey and Roulin , but see Galván et al ). When feathers absorb solar radiation, the photon energy is converted into radiative heat, improving thermoregulation in cold environments by warming trapped air against the skin (McGinness and Proctor , Margalida et al ).…”

Section: Alternative Predictions For Variation In Feather Traits (Plumentioning

confidence: 99%

Feather melanin and microstructure variation in dark‐eyed juncoJunco hyemalisacross an elevational gradient in the Selkirk Mountains

Zwaan

Greenwood

Martin

2017

Journal of Avian Biology

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Variation in feather melanism and microstructure can arise through sexual selection and ecological functional drivers. Melanin‐based plumage traits are associated with sexual dichromatism and the intensity of sexual selection in many avian species, but also have several ecological benefits such as protection against ultra‐violet (UV) radiation, camouflage, and feather strength. Additionally, feather microstructure influences thermoregulation. Plumage variation across species is well documented; however, the relative role of sexual selection and ecological drivers in intra‐specific and within‐population variation is less established. We investigated UV reflectance, melanism, and feather microstructure in a population of Oregon dark‐eyed juncos Junco hyemalis oreganus between high (1900–2200 m a.s.l.) and low (450–800 m a.s.l.) elevations in the Selkirk Mountains to evaluate potential sexual selection and ecological drivers of variation. We found no difference in UV reflectance or lightness (melanism) of head feathers between elevations, but individuals at high elevation had lighter (less melanism) and less brown (less pheomelanin) body contour feathers than at low elevations. High elevation individuals also had longer contour feathers with more pronounced plumulaceous regions. Sexual dichromatism did not vary between elevations, leading us to reject sexual selection in favour of ecological functional drivers of plumage variation in this system. To our knowledge, this is the first study to identify within‐population differences in feather melanism and microstructure between different elevations.

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“…In vertebrates, melanins are distributed through epidermal tissues and their derivatives, where the colour they impart plays important roles in social and predator -prey interactions, thermoregulation and ultraviolet (UV) protection [29,30]. In addition, internal organs and tissues, such as the liver, spleen, brain and inner ear, also contain melanin, which contributes to physiological processes and disease resistance [30, fig.…”

Section: Vertebrate Melanogenesismentioning

confidence: 99%

Interpreting melanin-based coloration through deep time: a critical review

et al. 2015

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Colour, derived primarily from melanin and/or carotenoid pigments, is integral to many aspects of behaviour in living vertebrates, including social signalling, sexual display and crypsis. Thus, identifying biochromes in extinct animals can shed light on the acquisition and evolution of these biological traits. Both eumelanin and melanin-containing cellular organelles (melanosomes) are preserved in fossils, but recognizing traces of ancient melanin-based coloration is fraught with interpretative ambiguity, especially when observations are based on morphological evidence alone. Assigning microbodies (or, more often reported, their ‘mouldic impressions’) as melanosome traces without adequately excluding a bacterial origin is also problematic because microbes are pervasive and intimately involved in organismal degradation. Additionally, some forms synthesize melanin. In this review, we survey both vertebrate and microbial melanization, and explore the conflicts influencing assessment of microbodies preserved in association with ancient animal soft tissues. We discuss the types of data used to interpret fossil melanosomes and evaluate whether these are sufficient for definitive diagnosis. Finally, we outline an integrated morphological and geochemical approach for detecting endogenous pigment remains and associated microstructures in multimillion-year-old fossils.

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Evolutionary and biomedical consequences of internal melanins

Cited by 68 publications

References 145 publications

Comparative histology in the liver and spleen of three species of freshwater teleost

Comparative histology in the liver and spleen of three species of freshwater teleost

Feather melanin and microstructure variation in dark‐eyed juncoJunco hyemalisacross an elevational gradient in the Selkirk Mountains

Interpreting melanin-based coloration through deep time: a critical review

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