Dispersive Raman spectroscopy allows the identification and quantification of melanin types

Galván, Ismael; Jorge, Alberto

doi:10.1002/ece3.1453

Cited by 35 publications

(35 citation statements)

References 17 publications

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“…Pheomelanin shows a distinctive Raman spectrum comprising three diagnostic bands located at 500, 1,500 and 2,000 cm −1 , and eumelanin shows different spectra with other diagnostic bands (Galván & Jorge, ; Galván et al, ; Polidori, Jorge, & Ornosa, ; Wang et al, ). In the flank feathers of male zebra finches, we only detected Raman signal from pheomelanin together with bands that can be assigned to keratin (Hsu, Moore, & Krimm, ).…”

Section: Methodsmentioning

confidence: 99%

Exposure to a competitive social environment activates an epigenetic mechanism that limits pheomelanin synthesis in zebra finches

Rodríguez‐Martínez

Galván

2019

Molecular Ecology

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Competitive environments promote high testosterone levels, produce 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, we experimentally increased social interactions in some zebra finch (Taeniopygia guttata) males by keeping them in groups of six birds during feather growth, while others were kept alone, to test if melanocytes show epigenetic lability under a competitive social environment. As these changes may depend on the oxidative status, we administrated buthionine sulfoximine (BSO) to decrease the antioxidant capacity of some birds. The competitive environment downregulated a gene involved in pheomelanin synthesis (Slc7a11) by changing the level of DNA methylation in feather melanocytes. In other genes involved in pheomelanin synthesis (Slc45a2, MC1R and AGRP), DNA methylation was also affected, but no changes in expression were detected. Exposure to the competitive environment did not affect systemic oxidative stress and damage, indicating that a protective epigenetic mechanism that changes the expression of Slc7a11 may have been activated. However, no changes to the pigmentation phenotype of birds were found, probably due to the short duration or low intensity of the competitive environment. BSO treatment did not affect the epigenetic mechanism, suggesting that the antioxidant capacity of birds was high enough to deal with the competitive environment. An epigenetic mechanism limiting pheomelanin synthesis therefore becomes activated under exposure to a competitive environment in male zebra finches, which may help to avoid damage caused by competitive interactions.

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Section: Methodsmentioning

confidence: 99%

Exposure to a competitive social environment activates an epigenetic mechanism that limits pheomelanin synthesis in zebra finches

Rodríguez‐Martínez

Galván

2019

Molecular Ecology

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“…The flank feathers of 16 nuthatch nestlings from 2017 were analyzed by micro-Raman spectroscopy to determine their relative content of melanins, as both pheomelanin and the non-sulphurated form of melanin (eumelanin) exhibit distinctive Raman signal that can be used to non-invasively identify and quantify them Jorge 2015). We used a Thermo Fisher DXR confocal dispersive Raman microscope (Thermo Fisher Scientific, Madison, WI, USA) with a point-and-shoot Raman capability of 1 µm spatial resolution and using a NIR excitation laser of 780 nm.…”

Section: Analysis Of Feather Pheomelanin Contentmentioning

confidence: 99%

Females mate with males with diminished pheomelanin‐based coloration in the Eurasian nuthatch Sitta europaea

Galván

Rodríguez‐Martínez

2018

Journal of Avian Biology

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Sexual selection can drive the evolution of phenotypic traits because of female preferences for exaggerated trait expression in males. Sexual selection can also lead to the evolutionary loss of traits, a process to which female preferences for diminished male trait expression are hypothesized to contribute. However, empirical evidence of female preferences for diminished male traits is virtually lacking. Eurasian nuthatches Sitta europaea provide an opportunity to test this possibility, as a chestnut flank patch produced by the pigment pheomelanin is present since the first plumage of these birds and its color is more intense in nestlings in poor condition in our study population. It has been proposed that developing birds in poor condition may increase their production of pheomelanin as a detoxifying strategy. Female nuthatches may thus prefer mating with males showing flank feathers of diminished color, as this could indicate that males experienced good conditions early in development, which can positively affect the fitness of future generations. Here we show results according with this prediction in a wild population of Eurasian nuthatches, as adult males with lighter chestnut feathers paired earlier in the season, while chestnut coloration had no effect on female mating success. Chestnut color expression was not affected by the body condition of birds, suggesting that females obtain information on the body condition in early life of their potential mates and not on their current body condition. This constitutes one of the few examples of females mating with males showing diminished traits and provides the only explanation so far by which this process can occur.

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“…used Raman spectroscopy as a non‐invasive technique for distinguishing eumelanin and pheomelanin pigments in the samples of partridge feathers, human and wild boar hairs. Recently, Galvan and Jorge characterized melanin pigments in bird feathers and reported that best results were achieved with the 785‐nm wavelength while keeping the laser power under 2 mW to avoid fluorescence disturbances. The pigments derived from sepia ink were historically used as the black colour pigments, and Raman spectroscopy was used to analyse melanin pigments in works of art .…”

Section: Introductionmentioning

confidence: 99%

Raman microspectrometric study of pigments in melanized fungi from the hyperarid Atacama desert gypsum crust

Culka

Jehlička

Ascaso

et al. 2017

J Raman Spectroscopy

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The Atacama desert is amongst the oldest and driest deserts in the world, and its hyperarid core is described as ‘the most barren region imaginable’. In this study, we describe for the first time the endolithic microbial communities composed by eukaryotic microorganisms, such as melanized fungi and algae, colonizing the interior of gypsum crusts collected in the hyperarid zone of the Atacama desert. Melanin pigments present in fungi cell walls have been studied by Raman microspectroscopy. Analyses have been performed directly in the gypsum crust sustaining the colonisation of fungi and algae, on the thin sections and on the cultivated culture of the fungi from Neocatenulostroma genus. Raman spectroscopic signature of melanin has been clearly observed in all the sample types. Two broad bands located at wavenumbers 1605–1580 cm−1 and around 1350 cm−1 have been detected in all the studied samples, with slight variations in the appearance of other bands or shoulders of smaller intensity documenting either the changes in melanin composition or other biomolecules bound to melanin. Blue and green lasers (445, 514 and 532 nm) have been shown as favourable excitation for the study of melanins as the longer wavelengths induced adverse effects that mask the Raman signal. Effect of laser power level on the resulting spectra has also been discussed. Algal carotenoid pigment has been detected in isolated regions of the sample by the Raman bands of 1520, 1155 and 1002 cm−1. The strong Raman signal of fungal melanin that has been detected in the host rock from the locality characterized by extreme conditions such as Atacama desert could be considered in the discussion about feasible biomarker molecules; however, low specificity of the broad Raman signature and similarity to the spectrum of amorphous carbon must be also taken into account. Copyright © 2017 John Wiley & Sons, Ltd.

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Dispersive Raman spectroscopy allows the identification and quantification of melanin types

Cited by 35 publications

References 17 publications

Exposure to a competitive social environment activates an epigenetic mechanism that limits pheomelanin synthesis in zebra finches

Exposure to a competitive social environment activates an epigenetic mechanism that limits pheomelanin synthesis in zebra finches

Females mate with males with diminished pheomelanin‐based coloration in the Eurasian nuthatch Sitta europaea

Raman microspectrometric study of pigments in melanized fungi from the hyperarid Atacama desert gypsum crust

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