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Current Biology : CB Aug 2018Pigmentation is a fundamental characteristic of living organisms that is used to absorb radiation energy and to regulate temperature. Since darker pigments absorb more...
Pigmentation is a fundamental characteristic of living organisms that is used to absorb radiation energy and to regulate temperature. Since darker pigments absorb more radiation than lighter ones, they stream more heat, which can provide an adaptive advantage at higher latitudes and a disadvantage near the Tropics, because of the risk of overheating. This intuitive process of color-mediated thermoregulation, also known as the theory of thermal melanism (TTM), has been only tested in ectothermic animal models [1-8]. Here, we report an association between yeast pigmentation and their latitude of isolation, with dark-pigmented isolates being more frequent away from the Tropics. To measure the impact of microbial pigmentation in energy capture from radiation, we generated 20 pigmented variants of Cryptococcus neoformans and Candida spp. Infrared thermography revealed that dark-pigmented yeasts heated up faster and reached higher temperatures (up to 2-fold) than lighter ones following irradiation. Melanin-pigmented C. neoformans exhibited a growth advantage relative to non-melanized yeasts when incubated under the light at 4°C but increased thermal susceptibility at 25°C ambient temperatures. Our results extend the TTM to microbiology and suggest pigmentation as an ancient adaptation mechanism for gaining thermal energy from radiation. The contribution of microbial pigmentation in heat absorption is relevant to microbial ecology and for estimating global temperatures. The color variations available in yeasts provide new opportunities in chromatology to quantify radiative heat transfer and validate biophysical models of heat flow [9] that are not possible with plants or animals.
Topics: Acclimatization; Body Temperature Regulation; Candida; Cryptococcus neoformans; Hot Temperature; Pigmentation
PubMed: 30078567
DOI: 10.1016/j.cub.2018.06.034 -
Scientific Reports Mar 2023Cuticle pigmentation was shown to be associated with body temperature for several relatively large species of insects, but it was questioned for small insects. Here we...
Cuticle pigmentation was shown to be associated with body temperature for several relatively large species of insects, but it was questioned for small insects. Here we used a thermal camera to assess the association between drosophilid cuticle pigmentation and body temperature increase when individuals are exposed to light. We compared mutants of large effects within species (Drosophila melanogaster ebony and yellow mutants). Then we analyzed the impact of naturally occurring pigmentation variation within species complexes (Drosophila americana/Drosophila novamexicana and Drosophila yakuba/Drosophila santomea). Finally we analyzed lines of D. melanogaster with moderate differences in pigmentation. We found significant differences in temperatures for each of the four pairs we analyzed. The temperature differences appeared to be proportional to the differently pigmented area: between Drosophila melanogaster ebony and yellow mutants or between Drosophila americana and Drosophila novamexicana, for which the whole body is differently pigmented, the temperature difference was around 0.6 °C ± 0.2 °C. By contrast, between D. yakuba and D. santomea or between Drosophila melanogaster Dark and Pale lines, for which only the posterior abdomen is differentially pigmented, we detected a temperature difference of about 0.14 °C ± 0.10 °C. This strongly suggests that cuticle pigmentation has ecological implications in drosophilids regarding adaptation to environmental temperature.
Topics: Animals; Body Temperature; Drosophila melanogaster; Fever; Drosophila; Pigmentation; Diospyros
PubMed: 36864153
DOI: 10.1038/s41598-023-30652-6 -
Developmental Dynamics : An Official... Oct 2021Amphibians possess three kinds of dermal chromatophore: melanophores, iridophores, and xanthophores. Knockout Xenopus tropicalis that lack the pigmentation of...
BACKGROUND
Amphibians possess three kinds of dermal chromatophore: melanophores, iridophores, and xanthophores. Knockout Xenopus tropicalis that lack the pigmentation of melanophores and iridophores have been reported. The identification of the causal genes for xanthophore pigmentation or differentiation could lead to the creation of a see-through frog without three chromatophores. The genes causing xanthophore differentiation mutants are slc2a11b and slc2a15b in Japanese medaka (Oryzias latipes).
RESULTS
To obtain a heritable line of X tropicalis mutants without yellow pigment, we generated slc2a7 and slc2a15a knockout animals because they have the greatest similarity to the O latipes slc2a11b and slc2a15b genes. The slc2a7 knockout frog had a bluish skin and there were no visible yellow pigments in stereo microscope and skin section observations. Furthermore, no pterinosomes, which are characteristic of xanthophores, were observed via transmission electron microscopy in the skin of knockout animals.
CONCLUSIONS
We report the successful generation of a heritable no-yellow-pigment X tropicalis mutant after knock out of the slc2a7 gene. This finding will enable the creation of a see-through frog with no chromatophores.
Topics: Animals; Animals, Genetically Modified; Chromatophores; Gene Expression Regulation, Developmental; Gene Knockout Techniques; Glucose Transport Proteins, Facilitative; Melanophores; Pigmentation; Xenopus
PubMed: 33760303
DOI: 10.1002/dvdy.334 -
Scientific Reports Apr 2022CRISPR/Cas9 technology enables the extension of genetic techniques into insect pests previously refractory to genetic analysis. We report the establishment of genetic...
CRISPR/Cas9 technology enables the extension of genetic techniques into insect pests previously refractory to genetic analysis. We report the establishment of genetic analysis in the glassy-winged sharpshooter (GWSS), Homalodisca vitripennis, which is a significant leafhopper pest of agriculture in California. We use a novel and simple approach of embryo microinjection in situ on the host plant and obtain high frequency mutagenesis, in excess of 55%, of the cinnabar and white eye pigmentation loci. Through pair matings, we obtained 100% transmission of w and cn alleles to the G3 generation and also established that both genes are located on autosomes. Our analysis of wing phenotype revealed an unexpected discovery of the participation of pteridine pigments in wing and wing-vein coloration, indicating a role for these pigments beyond eye color. We used amplicon sequencing to examine the extent of off-target mutagenesis in adults arising from injected eggs, which was found to be negligible or non-existent. Our data show that GWSS can be easily developed as a genetic model system for the Hemiptera, enabling the study of traits that contribute to the success of invasive pests and vectors of plant pathogens. This will facilitate novel genetic control strategies.
Topics: Animals; CRISPR-Cas Systems; Hemiptera; Pigmentation
PubMed: 35440677
DOI: 10.1038/s41598-022-09990-4 -
Journal of Biomedical Optics Mar 2022Spatial frequency domain imaging (SFDI) is a wide-field diffuse optical imaging technique for separately quantifying tissue reduced scattering (μs ' ) and...
SIGNIFICANCE
Spatial frequency domain imaging (SFDI) is a wide-field diffuse optical imaging technique for separately quantifying tissue reduced scattering (μs ' ) and absorption (μa) coefficients at multiple wavelengths, providing wide potential utility for clinical applications such as burn wound characterization and cancer detection. However, measured μs ' and μa can be confounded by absorption from melanin in patients with highly pigmented skin. This issue arises because epidermal melanin is highly absorbing for visible wavelengths and standard homogeneous light-tissue interaction models do not properly account for this complexity. Tristimulus colorimetry (which quantifies pigmentation using the L * "lightness" parameter) can provide a point of comparison between μa, μs ' , and skin pigmentation.
AIM
We systematically compare SFDI and colorimetry parameters to quantify confounding effects of pigmentation on measured skin μs ' and μa. We assess the correlation between SFDI and colorimetry parameters as a function of wavelength.
APPROACH
μs ' and μa from the palm and ventral forearm were measured for 15 healthy subjects with a wide range of skin pigmentation levels (Fitzpatrick types I to VI) using a Reflect RS® (Modulim, Inc., Irvine, California) SFDI instrument (eight wavelengths, 471 to 851 nm). L * was measured using a Chroma Meter CR-400 (Konica Minolta Sensing, Inc., Tokyo). Linear correlation coefficients were calculated between L * and μs ' and between L * and μa at all wavelengths.
RESULTS
For the ventral forearm, strong linear correlations between measured L * and μs ' values were observed at shorter wavelengths (R > 0.92 at ≤659 nm), where absorption from melanin confounded the measured μs ' . These correlations were weaker for the palm (R < 0.59 at ≤659 nm), which has less melanin than the forearm. Similar relationships were observed between L * and μa.
CONCLUSIONS
We quantified the effects of epidermal melanin on skin μs ' and μa measured with SFDI. This information may help characterize and correct pigmentation-related inaccuracies in SFDI skin measurements.
Topics: Colorimetry; Epidermis; Humans; Optical Imaging; Skin; Skin Pigmentation
PubMed: 35324096
DOI: 10.1117/1.JBO.27.3.036002 -
American Journal of Veterinary Research Aug 2022To assess the presence of suspected pigment-associated deafness in North American yaks (Bos grunniens).
OBJECTIVE
To assess the presence of suspected pigment-associated deafness in North American yaks (Bos grunniens).
ANIMALS
12 North American yaks, including 11 with the homozygous piebald Royal pigmentation phenotype and 1 with the heterozygous piebald Trim phenotype.
PROCEDURES
Hearing was assessed using the brainstem auditory evoked response (BAER) on yaks restrained in the head gate of a grooming chute.
RESULTS
Five of the Royal yaks and the Trim yak had hearing in both ears. Six Royal yaks were affected; 3 were deaf in 1 ear and 3 were deaf in both ears.
CLINICAL RELEVANCE
For the first time, probable sensorineural deafness has been confirmed to be present in Royal yaks. The disorder is assumed to be congenital and associated with white pigmentation, based on the pattern of occurrence in other species.
Topics: Animals; Cattle; Cattle Diseases; Deafness; North America; Phenotype; Pigmentation
PubMed: 35914095
DOI: 10.2460/ajvr.22.03.0050 -
Frontiers in Bioscience (Elite Edition) Jan 2015The mechanisms of asymmetric organ development have been under intensive investigation for years, yet the proposed mechanisms remain controversial (1-3). The female... (Review)
Review
The mechanisms of asymmetric organ development have been under intensive investigation for years, yet the proposed mechanisms remain controversial (1-3). The female Bruchus quadrimaculatus beetle insect develops two black-colored spots bilaterally located on each upper elytra wing by an unknown mechanism. Fifty percent of the P (for piebald, two colors) gene homozygous mutant insects, described in 1925, had a normal left elytrum (with two black spots) and an abnormal right elytrum (with two red spots) and the balance supported the converse lateralized pigment arrangement (4). Rather than supporting the conventional morphogen model for the wings pigmentation development, their biological origin is explained here with the somatic strand-specific epigenetic imprinting and selective sister chromatid segregation (SSIS) mechanism (5). We propose that the P gene product performs the selective sister chromatid segregation function to produce symmetric cell division of a specific cell during embryogenesis to result in the bilateral symmetric development of elytra black color spots and that the altered chromatid segregation pattern of the mutant causes asymmetric cell division to confer the piebald phenotype.
Topics: Animals; Chromatids; Chromosome Segregation; Coleoptera; Epigenesis, Genetic; Models, Genetic; Morphogenesis; Phenotype; Pigmentation; Schizosaccharomyces; Wings, Animal
PubMed: 25553380
DOI: 10.2741/E734 -
Scientific Reports Mar 2023Tasmania is experiencing increasing seawater temperatures during the summer period which often leads to thermal stress-induced starvation events in farmed Atlantic...
Histological and transcriptomic analysis of muscular atrophy associated with depleted flesh pigmentation in Atlantic salmon (Salmo salar) exposed to elevated seawater temperatures.
Tasmania is experiencing increasing seawater temperatures during the summer period which often leads to thermal stress-induced starvation events in farmed Atlantic salmon, with consequent flesh pigment depletion. Our previous transcriptomic studies found a link between flesh pigmentation and the expression of genes regulating lipid metabolism accompanied by feeding behavior in the hindgut. However, the impact of prolonged exposure to elevated water temperature on muscle structural integrity and molecular mechanisms in muscle underlying pigment variation has not been elucidated to date. In this study, we investigated the effect of prolonged exposure to elevated water temperature on the farmed salmon flesh pigmentation and structural integrity, using muscle histological and transcriptomic analysis. On April 2019, after the end of the summer, two muscle regions of the fish fillet, front dorsal and back central (usually the most and least affected by depletion, respectively), were sampled from fifteen fish (weighing approximately 2 kg and belonging to the same commercial population split in two cages). The fish represented three flesh color intensity groups (n = 5 fish per group) categorized according to general level of pigmentation and presence of banding (i.e. difference in color between the two regions of interest) as follows: high red color-no banding (HN), high red color-banded (HB) and Pale fish. Histological analysis showed a distinction between the flesh color intensity phenotypes in both muscle regions. Muscle fibers in the HB fish were partly degraded, while they were atrophied and smaller in size in Pale fish compared to HN fish. In the Pale fish, interstitial spaces between muscle fibers were also enlarged. Transcriptomic analysis showed that in the front dorsal region of the HN fish, genes encoding collagens, calcium ion binding and metabolic processes were upregulated while genes related to lipid and fatty acid metabolism were downregulated when compared to HB fish. When comparing the back central region of the three phenotypes, actin alpha skeletal muscle and myosin genes were upregulated in the HN and HB fish, while tropomyosin genes were upregulated in the Pale fish. Also, genes encoding heat shock proteins were upregulated in the HN fish, while genes involving lipid metabolism and proteolysis were upregulated in the Pale fish. Starvation, likely caused by thermal stress during prolonged periods of elevated summer water temperatures, negatively affects energy metabolism to different extents, leading to localized or almost complete flesh color depletion in farmed Atlantic salmon. Based on our results, we conclude that thermal stress is responsible not only for flesh discoloration but also for loss of muscle integrity, which likely plays a key role in pigment depletion.
Topics: Animals; Salmo salar; Temperature; Transcriptome; Pigmentation; Muscle, Skeletal; Muscular Atrophy; Seawater; Water
PubMed: 36918611
DOI: 10.1038/s41598-023-31242-2 -
Pigment Cell & Melanoma Research Nov 2014The pigmentation of mammalian skin and hair develops through the interaction of two basic cell types - pigment donors and recipients. The pigment donors are melanocytes,... (Review)
Review
The pigmentation of mammalian skin and hair develops through the interaction of two basic cell types - pigment donors and recipients. The pigment donors are melanocytes, which produce and distribute melanin through specialized structures. The pigment recipients are epithelial cells, which acquire melanin and put it to use, collectively yielding the pigmentation visible to the eye. This review will focus on the pigment recipients, the historically less understood cell type. These end-users of pigment are now known to exert a specialized control over the patterning of pigmentation, as they identify themselves as melanocyte targets, recruit pigment donors, and stimulate the transfer of melanin. As such, this review will discuss the evidence that the skin is like a coloring book: the pigment recipients create a 'picture,' a blueprint for pigmentation, which is colorless initially but outlines where pigment should be placed. Melanocytes then melanize the recipients and 'color in' the picture.
Topics: Animals; Epithelial Cells; Humans; Phenotype; Pigmentation; Pigments, Biological; Skin
PubMed: 25104547
DOI: 10.1111/pcmr.12301 -
Scientific Reports Sep 2019Melanin pigment has a significant role in ocular pharmacokinetics, because many drugs bind at high extent to melanin in the retinal pigment epithelial cells. Most...
Melanin pigment has a significant role in ocular pharmacokinetics, because many drugs bind at high extent to melanin in the retinal pigment epithelial cells. Most retinal pigment epithelial cell lines lack pigmentation and, therefore, we re-pigmented human ARPE-19 cells to generate a pigmented cell model. Melanosomes from porcine retinal pigment epithelium were isolated and co-incubated with ARPE-19 cells that spontaneously phagocytosed the melanosomes. Internalized melanosomes were functionally integrated to the cellular system as evidenced by correct translocation of cellular Rab27a protein to the melanosomal membranes. The pigmentation was retained during cell cultivation and the level of pigmentation can be controlled by altering the amount of administered melanosomes. We used these cells to study melanosomal uptake of six drugs. The uptake was negligible with low melanin-binders (methotrexate, diclofenac) whereas most of the high melanin-binders (propranolol, chloroquine) were extensively taken up by the melanosomes. This cell line can be used to model pigmentation of the retinal pigment epithelium, while maintaining the beneficial cell line characteristics, such as fast generation of cultures, low cost, long-term maintenance and good reproducibility. The model enables studies at normal and decreased levels of pigmentation to model different retinal conditions.
Topics: Animals; Biological Transport; Cell Line; Chloroquine; Diclofenac; Humans; Melanins; Melanosomes; Methotrexate; Phagocytosis; Pigmentation; Propranolol; Retina; Retinal Pigment Epithelium; Retinal Pigments; Swine
PubMed: 31551473
DOI: 10.1038/s41598-019-50324-8