Absence Of Melanin Research Articles

A pipeline for processing hyperspectral images, with a case of melanin-containing barley grains as an example.

Analysis of hyperspectral images is of great interest in plant studies. Nowadays, this analysis is used more and more widely, so the development of hyperspectral image processing methods is an urgent task. This paper presents a hyperspectral image processing pipeline that includes: preprocessing, basic statistical analysis, visualization of a multichannel hyperspectral image, and solving classification and clustering problems using machine learning methods. The current version of the package implements the following methods: construction of a confidence interval of an arbitrary level for the difference of sample averages; verification of the similarity of intensity distributions of spectral lines for two sets of hyperspectral images on the basis of the Mann-Whitney U-criterion and Pearson's criterion of agreement; visualization in two-dimensional space using dimensionality reduction methods PCA, ISOMAP and UMAP; classification using linear or ridge regression, random forest and catboost; clustering of samples using the EM-algorithm. The software pipeline is implemented in Python using the Pandas, NumPy, OpenCV, SciPy, Sklearn, Umap, CatBoost and Plotly libraries. The source code is available at: https://github.com/igor2704/Hyperspectral_images. The pipeline was applied to identify melanin pigment in the shell of barley grains based on hyperspectral data. Visualization based on PCA, UMAP and ISOMAP methods, as well as the use of clustering algorithms, showed that a linear separation of grain samples with and without pigmentation could be performed with high accuracy based on hyperspectral data. The analysis revealed statistically significant differences in the distribution of median intensities for samples of images of grains with and without pigmentation. Thus, it was demonstrated that hyperspectral images can be used to determine the presence or absence of melanin in barley grains with great accuracy. The flexible and convenient tool created in this work will significantly increase the efficiency of hyperspectral image analysis.

First record of ocular albinism in sub-Antarctic fur seal (Arctocephalus tropicalis) pups on Marion Island

We report on an occurrence of ocular albinism in sub-Antarctic fur seal (Arctocephalus tropicalis) pups born on Marion Island, Prince Edward Archipelago. While previous observations have documented pups with atypical lanugo pelage colorations, this is the first case involving hypopigmentation of both fur and other tissues, including the eyes and nails. During the austral summer of 2021/22, we encountered four sub-Antarctic fur seal pups displaying this anomalous pigmentation. These anomalous individuals were found along two beaches on the island’s western side and one beach on the eastern side during an island-wide fur seal census. Although the characteristics observed strongly suggest ocular albinism, confirmation would be necessary through genetic analyses. The absence of melanin in mammalian eyes is known to compromise visual acuity, which may likely result in reduced survival beyond the weaning period, explaining the paucity of such adults in this well-observed population.

Poliosis, hair pigment dilution, and premature graying of the hair: A diagnostic approach in pediatric patients and review of the literature.

Poliosis is defined as the absence of melanin in hair, and hair graying typically occurs with hair melanin reduction. Poliosis can occur at any age but presents in childhood in certain genetic and acquired conditions, with many families seeking evaluation from a pediatric dermatologist. Poliosis presents as white hair typically restricted to a certain location of the scalp. Children may also present with a reduction of expected hair pigmentation, referred to as pigment dilution, or the development of hair graying. This review aims to provide a streamlined diagnostic approach for pediatric dermatologists when presented with these hair findings. Poliosis should be recognized as a potential diagnostic feature or initial sign in many syndromes and thus can guide clinicians in diagnosing and managing conditions earlier in a patient's care. Since many of the genetic and acquired conditions that present with poliosis or hair pigment dilution have extracutaneous manifestations, early diagnosis is vital in establishing multidisciplinary care.

Knockout of Hermansky-Pudlak syndrome 5 (hps5) leads to red tilapia with reduced melanophores and iridophores

Tilapia as an economically important fish is also an excellent model for studying pigment cell biology and body color formation. In the present study, we engineered a red tilapia by mutation of hps5 using CRISPR/Cas9 gene editing of a target site in exon 2. Disruption of HPS5 led to a significant decrease in the numbers of melanophores and iridophores, and a significant increase in xanthophores, which led to a yellowish-transparent body color in early stages (5–30 dpf, days post fertilization). Slow recovery of iridophore numbers, and increased numbers of xanthophores with shorter nearest-neighbor distances than in wild-type fish was observed at 150 dpf, which finally led to a red tilapia with reddish pigmentation in fins. The hps5−/− mutants also showed several transparent cracks (absence of melanin, iridophores and xanthophores) in iris development. Besides, hps5 was also found to be fundamental for xanthophore development, and even the distance between each of them. Our hps5 mutants provide an excellent new model for studies of HPS5 function. Additionally, the red tilapia mutants may also have potential to serve as new germplasm for aquaculture, or function as a gene resource for genetic modification and breeding of red tilapia and the other related ornamental and food fish in aquaculture. More importantly, this study may have significant values in the area of development and evolution of pigmentation patterns of fish species.

Transcriptomic and genomic effects of gamma-radiation exposure on strains of the black yeast Exophiala dermatitidis evolved to display increased ionizing radiation resistance.

Ionizing radiation poses a significant threat to living organisms and human health, given its destructive nature and widespread use in fields such as medicine and the potential for nuclear disasters. Melanized fungi exhibit remarkable survival capabilities, enduring doses up to 1,000-fold higher than mammals. Through adaptive laboratory evolution, we validated the protective role of constitutive upregulation of DNA repair genes in the black yeast Exophiala dermatitidis, enhancing survival after radiation exposure. Surprisingly, we found that evolved strains lacking melanin still achieved high levels of radioresistance. Our study unveiled the significance of robust activation and enhancement of redox homeostasis, as evidenced by the profound transcriptional changes and increased accumulation of mutations, in substantially improving ionizing radiation resistance in the absence of melanin. These findings underscore the delicate balance between DNA repair and redox homeostasis for an organism's ability to endure and recover from radiation exposure.

On-demand delivery of protein drug from 3D-printed implants.

Here, we constructed 3D-printed multiunit implants to enable remote light-controlled protein drug delivery in a spatiotemporal manner. Multiunit implants were designed to be 3D printed using polycaprolactone, lauric acid, and melanin as a matrix, and a polycaprolactone scaffold as a multiunit divider. As a model drug, insulin was loaded to each unit of the implant. The 3D printing yielded a rectangular matrix with multiunit sectors segregated by polycaprolactone lanes. Irradiation with near infrared light (NIR) triggered controlled release of insulin from the irradiated locus: Upon NIR irradiation, heat generated from the melanin melted the polycaprolactone/lauric acid matrix to release insulin from the scaffold. In the absence of melanin in the matrix, the implant did not show NIR-responsive insulin release. When lauric acid was absent from the matrix, the NIR-irradiated unit did not undergo dismantling. When the insulin-loaded multiunit implant was applied to a mouse diabetic model and irradiated with NIR, repetitive insulin release resulted in an efficient decrease of the blood glucose level over multiple days. Together, these results suggest that 3D printing technology-based multi-dosing of insulin on demand can enable convenient treatment of diabetes through external NIR irradiation, potentially avoiding the pain and discomfort of repeated insulin injections.

Interest of nails analysis to investigate synthetic cannabinoid exposure? A case report

Discuss the interest of nails analysis in the challenging investigation of synthetic cannabinoids (SC) exposure regarding the documentation of an acute intoxication by FUB-AMB (or AMB-FUBINACA or MMB-FUBINACA). A 20-year-old man was transferred to emergency department after report of a psychotic behavior since 6 days. His medical history and examination were unremarkable except for cannabis consummation and vaping habits. Toxicological investigations were performed in the seized e-liquid, in blood and urine sampled 12 h after hospitalization and in keratinous matrices sampled 23 days later: 4 cm length brown hair, fingernails and toenails clippings. After washing, (i) hair sample has been segmented, cut into small pieces and 20 mg were incubated 1 h at 60 °C in methanol, (ii) nails were mechanically grinded in fine powders and extraction was performed in methanol for 16 h at room temperature. Large toxicological screenings (CL-HRMS and CL-MS/MS) together with selective analysis were performed using previously published methods. FUB-AMB, detected in the e-liquid, was quantified in all biological samples: 227 and 55 ng/mL in serum and urine, respectively, and 570, 1250, 850 and 210 pg/mg in proximal hair segment (period of reported acute intoxication), distal hair segment, fingernails and toenails, respectively. Its major ester hydrolysis metabolite was detected in all biological samples except in hair. Ratio of signal of metabolite over parent substance is clearly higher in toenails than in fingernails: 57% versus 6%. To our knowledge, this case is the first report of FUB-AMB detection in nails. FUB-AMB main metabolite was detected only in nails, and was proportionally more important in toenails than in fingernails. Several elements can explain the differences in incorporation in keratinized matrices, e.g., absence of melanin in nail, way of incorporation depending on physicochemical properties of considered substance. In nails, foot sweating could have increased incorporation of metabolites and less frequent washing than hands reduce their elimination. In addition, FUB-AMB contain a labile ester. Strongly metabolized, this substance is weakly stable in blood in vitro at room temperature [Krotulski A et al. J Anal Tox 2021;45(1):60–85]. Whereas degradation of SC labile ester in hair was demonstrated [Franz F et al. Anal Bioanal Chem 2016;408(13):3445–52] their stability in nails is not demonstrated and, on the contrary, could be majored, especially in toenails. Nails analysis have to be interpreted cautiously. In this reported case, results in nails objectivized one or several former exposures to FUB-AMB without being able to specify their chronology nor their chronicity. While many studies investigate retrospective CS consumption using hair analysis, only one publication regarding SC in nails is reported in literature. This case illustrate the interest of this matrix to documented SC exposure but also, regarding all the parameters described, its potential use for prevalence studies of SC even if further investigations, such sensibility regarding more potent SC and occasional user, are required.

Melanin protects Cryptococcus neoformans from spaceflight effects.

SummaryAs human activity in space continues to increase, understanding how biological assets respond to spaceflight conditions is becoming more important. Spaceflight conditions include exposure to ionizing radiation, microgravity, spacecraft vibrations and hypervelocity; all of which can affect the viability of biological organisms. Previous studies have shown that melanin‐producing fungi are capable of surviving the vacuum of space and Mars‐simulated conditions in Low Earth Orbit. This survival has been associated in part with the protective effects of melanin, but a comparison of fungal viability in the presence or absence of melanin following spaceflight has never been tested. In this study, we evaluated the protective effects of melanin by comparing the viability of melanized and non‐melanized clones of Cryptococcus neoformans yeasts following a roundtrip to the International Space Station. Yeast colonies were placed inside two MixStix silicone tubes; one stayed on Earth and the other was transported inside for 29 days before returning to Earth. Post‐flight analysis based on colony‐forming unit numbers shows that melanized yeast viability was 50% higher than non‐melanized yeasts, while no difference was observed between the Earth‐bound control samples. The results suggest that fungal melanin could increase the lifespan of biological assets in space.

Creation of Non-Contact Device for Use in Metastatic Melanoma Margin Identification in ex vivo Mouse Brain.

Because contemporary intraoperative tumor detection modalities, such as intraoperative MRI, are not ubiquitously available and can disrupt surgical workflow, there is an imperative for an accessible diagnostic device that can meet the surgeon's needs in identifying tissue types. The objective of this paper is to determine the efficacy of a novel non-contact tumor detection device for metastatic melanoma boundary identification in a tissue-mimicking phantom, evaluate the identification of metastatic melanoma boundaries in ex vivo mouse brain tissue, and find the error associated with identifying this boundary. To validate the spatial and fluorescence resolution of the device, tissue-mimicking phantoms were created with modifiable optical properties. Phantom tissue provided ground truth measurements for fluorophore concentration differences with respect to spatial dimensions. Modeling metastatic disease, ex vivo melanoma brain metastases were evaluated to detect differences in fluorescence between healthy and neoplastic tissue. This analysis includes determining required-to-observe fluorescence differences in tissue. H&E staining confirmed tumor presence in mouse tissue samples. The device detected a difference in normalized average fluorescence intensity in all three phantoms. There were differences in fluorescence with the presence and absence of melanin. The estimated tumor boundary of all tissue phantoms was within 0.30 mm of the ground truth tumor boundary for all boundaries. Likewise, when applied to the melanoma-bearing brains from ex vivo mice, a difference in normalized fluorescence intensity was successfully detected. The potential prediction window for the tumor boundary location is less than 1.5 mm for all ex vivo mouse brain tumors boundaries. We present a non-contact, laser-induced fluorescence device that can identify tumor boundaries based on changes in laser-induced fluorescence emission intensity. The device can identify phantom ground truth tumor boundaries within 0.30 mm using instantaneous rate of change of normalized fluorescence emission intensity and can detect endogenous fluorescence differences in melanoma brain metastases in ex vivo mouse tissue.

First record of anomalous coloration for Eptesicus taddeii (Vespertilionidae) in the Atlantic Forest, South Brazil

Piebaldism is characterized by the absence of melanin in certain areas of the body due the lack of melanocytes as a result of genetic mutations, and which occurs only locally. This study reports the first record of piebaldism for Eptesicus taddeii, a species of bat, endemic to the Atlantic Forest in the South Region of Brazil.

The effect of albinism on avian predator attack rates in eastern garter snakes

Albinism is a conspicuous and distinctive phenotype arising from the absence of melanin in the integument that has been documented in all major vertebrate groups. With few exceptions, albinism is rare in natural populations, suggesting that it incurs significant fitness costs as compared to wild-type phenotypes. One possible explanation for this rarity is that albinos experience higher predation risk as compared to wild-type individuals. We tested this hypothesis by comparing rates of attack by avian predators on immobile clay model proxies that mimicked wild-type and albino eastern garter snakes (Thamnophis s. sirtalis) at Bond Swamp in central Georgia, USA; two mixed pattern treatments provided intermediate phenotypes for comparison. Surprisingly, we found no difference in attack rate across all four model treatments, nor among pairs of treatments (i.e., wild-type-like vs. albino-like models). This indicates that albino garter snakes are not subject to higher predation risk from birds due to coloration alone, and that other factors (correlated pathologies of albinism, thermoregulatory challenges, mate selection) are likely to be more important in explaining the rarity of albinism in snakes and perhaps other vertebrate groups.

A synergistic combination of structural and pigmentary colour produces non-spectral colour in the purple-breasted cotinga,Cotinga cotinga(Passeriformes: Cotingidae)

AbstractMost studies of animal coloration focus on spectral colours, which are colours evoked by single peaks within the wavelengths of visible light. It is poorly understood how non-spectral colours (those produced by a combination of reflectance peaks) are produced, despite their potential significance to both animal communication and biomimicry. Moreover, although both pigmentary and structural colour production mechanisms have been well characterized in feathers independently, their interactions have received considerably less attention, despite their potential to broaden the available colour spectrum. Here, we investigate the colour production mechanisms of the purple feathers of the purple-breasted cotinga (Cotinga cotinga). The purple feather colour results from both the coherent scattering of light by a sphere-type nanomatrix of β-keratin and air (spongy layer) in the barbs, which produces a blue–green colour, and the selective absorption of light in the centre of the bird-visible spectrum by the methoxy-carotenoid, cotingin. This unusual combination of carotenoid and nanostructure with a central air vacuole, in the absence of melanin, is a blueprint of a synergistic way to produce a non-spectral colour that would be difficult to achieve with only a single colour production mechanism.

Evident hypopigmentation without other ocular deficits in Dutch patients with oculocutaneous albinism type 4

To describe the phenotype of Dutch patients with oculocutaneous albinism type 4 (OCA4), we collected data on pigmentation (skin, hair, and eyes), visual acuity (VA), nystagmus, foveal hypoplasia, chiasmal misrouting, and molecular analyses of nine Dutch OCA4 patients from the Bartiméus Diagnostic Center for complex visual disorders. All patients had severely reduced pigmentation of skin, hair, and eyes with iris transillumination over 360 degrees. Three unrelated OCA4 patients had normal VA, no nystagmus, no foveal hypoplasia, and no misrouting of the visual pathways. Six patients had poor visual acuity (0.6 to 1.0 logMAR), nystagmus, severe foveal hypoplasia and misrouting. We found two novel variants in the SLC45A2 gene, c.310C > T; (p.Pro104Ser), and c.1368 + 3_1368 + 9del; (p.?). OCA4 patients of this Dutch cohort all had hypopigmentation of skin, hair, and iris translucency. However, patients were either severely affected with regard to visual acuity, foveal hypoplasia, and misrouting, or visually not affected at all. We describe for the first time OCA4 patients with an evident lack of pigmentation, but normal visual acuity, normal foveal development and absence of misrouting. This implies that absence of melanin does not invariably lead to foveal hypoplasia and abnormal routing of the visual pathways.

Albinism in a Yellow-bellied Earth Snake (Geophis godmani Boulenger, 1894) (Serpentes: Dipsadidae) from Central Costa Rica

Anomalous pigmentations have been reported in several groups of reptiles. Among these, albinism is one of the most striking aberrations of body coloration. This pigmentary anomaly is caused by the absence of melanin in the integument. Many cases of albinism have been reported in snakes, primarily in species with cryptozoic habits, and several reports are available for the Dipsadidae family from South America. Geophis is one of the most diverse genera in this family, with 50 species distributed mainly in Mesoamerica. The Yellow-bellied Earth Snake (Geophis godmani) is known only from the mountain ranges of Costa Rica and western Panama. In September, 2020 we encountered an albino individual of the Yellow-bellied Earth Snake at Palmira de Zarcero, Alajuela province, Costa Rica. Here we report on this finding and discuss possible consequences of albinism in snakes. Snakes affected by albinism have red eyes and a yellow or pink coloration due to the presence of xanthophores and erythrophores. As a result, aspects such as thermoregulation can be affected, and jeopardize the snake's survival. However, some individuals can have traits that potentially preclude the negative effects of albinism. These characteristics would allow for the survival of individual snakes to the adult stage, such as the albino individual of Geophis godmani we found in central Costa Rica.

First Report of Albinism in Turkish Crayfish Pontastacus leptodactylus (Eschscholtz, 1823) (Crustacea, Decapoda, Astacidae)

A female albino crayfish Pontastacus leptodactylus (Eschscholtz, 1823) was captured from Atikhisar Reservoir in Çanakkale, Turkey on July 18, 2020. The albino crayfish is lacked melanin that is normally found on normal crayfish. The compound eyes of the albino crayfish were black as in normal crayfish. Morphometric characteristics were measured and the total length was 101.98 mm, carapace length was 50.04 mm, carapace width was 26.56 mm and weight was 35.90 g. Albinism is a widespread disorder in the animal kingdom and is triggered by the absence of melanin in the skin, eyes, or hair. Investigation on albinism has commonly focused on mice and humans. Therefore, there is restricted research on albino crayfish. In the present paper, the occurrence of albinism in crayfish is firstly reported from Atikhisar Reservoir in Çanakkale, Turkey. Therefore, this paper significantly contributes to the scientific literature by providing the first knowledge on the presence of albino crayfish in the Atikhisar Reservoir, Çanakkale, Turkey.

Red and blond Mangalitza pigs display a signature of divergent directional selection in the SLC45A2 gene.

The Mangalitza lard-type pig breed is well known for its fat appearance and curly hair, and it is mainly distributed in Eastern Europe. Four main lines were created in the nineteenth century by artificial selection: Blond Mangalitza, Black Mangalitza, Swallow-Belly Mangalitza and Red Mangalitza. The Swallow-Belly line has a black coat combined with yellow-blond throat and underbelly. In the current work, we aimed to investigate if the colourations of Mangalitza pigs are genetically determined by one or a few loci whose frequencies have been modified by artificial selection. The results of selection scans, with HapFLK and BayeScan, and of a GWAS for coat colour highlighted the existence of one region on SSC16 (18-20Mb) with potential effects on hair pigmentation (Red vs. Blond contrast). The analysis of the gene content of this region allowed us to detect the solute carrier family 45 member 2 (SLC45A2) locus as a candidate gene for this trait. The polymorphism of the SLC45A2 locus has been associated with reduced levels or the absence of melanin in several mammalian species. The genotyping of four missense polymorphisms evidenced that rs341599992:G>A and rs693695020:G>A SNPs are strongly but not fully associated with the red and blond coat colours of Mangalitza pigs, a result that was confirmed by performing a haplotype association test. The near fixation of alternative SLC45A2 genotypes in Red and Blond Mangalitza pigs provides a compelling example of the consequences of a divergent directional selection for coat colour in a domestic species.

Hyphal morphology and substrate porosity -rather than melanization- drive penetration of black fungi into carbonate substrates

Abstract Due to their ability to penetrate, deteriorate and discolour stone surfaces, rock-inhabiting black fungi represent a remarkable issue for cultural heritage conservation. Black microcolonial fungi (MCF) can also adapt to different environmental conditions, by converting from yeast-like morphology to a peculiar meristematic development with swollen cells (torulose hyphae, TH), to extremely thin structures (filamentous hyphae, FH). Furthermore, black MCF produce protective pigments: melanin, dark pigment particularly evident on light stone surfaces, and carotenoids. Black fungi produce melanin in critical, oligotrophic conditions as well as constitutively. Melanin function is mostly related to stress resistance and the ability of fungi to generate appressorial turgor to actively penetrate plant cells in pathogenic species. An involvement of melanins in stone surface penetration has been suggested, but not experimentally proved. In this work, we tested the role of hyphal melanisation in penetration mechanisms on the model black fungus Knufia petricola A95 in lab conditions. The wild-type and three mutants with introduced targeted mutations of polyketide-synthases (melanin production) and/or phytoene dehydrogenase (carotenoid synthesis) were inoculated on artificial carbonate pellets (pressed Carrara marble powder) of different porosity. After 5, 10, 17 and 27 weeks, hyphal penetration depth and spread were quantified on periodic acid Schiff-stained cross-sections of the pellets, collecting measurements separately for TH and FH. Droplet assay of the mutants on different media were conducted to determine the role of nutrients in the development of different fungal morphologies. In our in vitro study, the hyphal penetration depth, never exceeding 200 μm, was proven to be consistent with observed penetration patterns on stone heritage carbonate substrates. Pellet porosity affected penetration patterns of TH, which developed in voids of the more porous pellets, instead than actively opening new passageways. Oppositely, the thin diameter of FH allowed their penetration independently of substrate porosity. Instead, the long-hypothesized crucial role of melanin in black MCF hyphal penetration should be rejected. TH were developed within the pellets also by melanin deficient strains, and melanized strains showed an endolithic component of non-melanized TH. FH were non-melanized for all the strains, but deeply penetrated all pellet types, with higher penetration depth probably related to their potential exploratory (nutrient-seeking) role, while TH may be more related to a resistance to surface stress factors. In the melanin deficient strains, the absence of melanin caused an increased penetration rate of FH, hypothetically related to an earlier necessity to search for organic nutrients.

Primer reporte de leucismo en la gallareta americana (Fulica americana) en el centro de México

El leucismo es una aberración cromática, definida como la ausencia de melanina, que se expresa de manera total o parcial en el plumaje de las aves. Registramos la presencia de leucismo en un individuo adulto de gallareta americana (Fulica americana) en el lago Nabor Carrillo en Texcoco, Estado de México. La gallareta americana es un ave de amplia distribución geográfica, común en hábitats acuáticos desde Alaska hasta el norte de Sudamérica. Observamos al individuo el 29 y 31 de mayo y el 26 de junio de 2020 en el cuerpo de agua. Aunque existen diversos reportes de aves con leucismo, este registro representa el primer caso documentado de leucismo para esta especie en México.

CO RELATIVE STUDY OF BHRAJAK PITTA AND MELANIN

Dosa dhatu mala are the basic principles of Ayurveda. In Ayurveda vata,pitta, kapha are the main 3 types of dosa. According to Vagbhata pitta has these main function namely pakti (digestion),ushma(maintain proper body temperature),darshan (vision), kshudha(hunger), trushna(thirst), prabha (lustre) to skin ,medha( intellect). Pathological increase in Pitta causes yellow coloured skin and eyes and decrease in Pitta causes loss of lustre and low glorification (prabhahani). pitta has five subtypes Aalochak ,Ranjak ,Sadhak ,Pachak and Bhrajak pitta . Bhrajak pitta is located in skin and its functions are regulation of body heat and maintain normal skin colour and absorption and digestion of medicine applied on skin. According to modern science the colour of skin depends upon melanin concentration. Excess level of melanin results in skin tanning while absence of melanin causes albinism. Co- relative study of Bhrajak Pitta and melanin may helpful to ayurvedic students to understand ayurvedic concept Bhrajak pitta in modern point of view hence, detail study of Bhrajak pitta and Melanin in has been elaborated in this article.

Porosity at Different Structural Levels in Human and Yak Belly Hair and Its Effect on Hair Dyeing.

Yak belly hair was proposed as a cheap substitute for human hair for the development of hair dyes, as its chemical composition closely resembles human hair in Raman spectroscopy. The absence of melanin in yak belly hair also leads to a strong reduction of fluorescence in Raman measurements, which is advantageous for the investigation of the effectivity of hair dyes. To assess the suitability for replacing human hair, we analyzed similarities and differences of both hair types with a variety of methods: Raman spectroscopy, to obtain molecular information; small-angle X-ray scattering to determine the nanostructure, such as intermediate filament distance, distance of lipid layers and nanoporosity; optical and scanning electron microscopy of surfaces and cross sections to determine the porosity at the microstructural level; and density measurements and tensile tests to determine the macroscopic structure, macroporosity and mechanical properties. Both types of hair are similar on a molecular scale, but differ on other length scales: yak belly hair has a smaller intermediate filament distance on the nanoscale. Most striking is a higher porosity of yak belly hair on all hierarchical levels, and a lower Young’s modulus on the macroscale. In addition to the higher porosity, yak belly hair has fewer overlapping scales of keratin, which further eases the uptake of coloring. This makes, on the other hand, a comparison of coloring processes difficult, and limits the usefulness of yak belly hair as a substitute for human hair.