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779 results for “pigment”
Data from: Human retinal pigment epithelium: in vivo cell morphometry, multispectral autofluorescence, and relationship to cone mosaic
Purpose: To characterize in vivo morphometry and multispectral autofluorescence of the retinal pigment epithelial (RPE) cell mosaic and its relationship to cone cell topography across the macula. Methods: RPE cell morphometrics were computed in regularly spaced regions of interest (ROIs) from contiguous short-wavelength autofluorescence (SWAF) and photoreceptor reflectance images collected across the macula in one eye of 10 normal participants (23–65 years) by using adaptive optics scanning light ophthalmoscopy (AOSLO). Infrared autofluorescence (IRAF) images of the RPE were collected with AOSLO in seven normal participants (22–65 years), with participant overlap, and compared to SWAF quantitatively and qualitatively. Results: RPE cell statistics could be analyzed in 84% of SWAF ROIs. RPE cell density consistently decreased with eccentricity from the fovea (participant mean ± SD: 6026 ± 1590 cells/mm2 at fovea; 4552 ± 1370 cells/mm2 and 3757 ± 1290 cells/mm2 at 3.5 mm temporally and nasally, respectively). Mean cone-to-RPE cell ratio decreased rapidly from 16.6 at the foveal center to <5 by 1 mm. IRAF revealed cells in six of seven participants, in agreement with SWAF RPE cell size and location. Differences in cell fluorescent structure, contrast, and visibility beneath vasculature were observed between modalities. Conclusions: Improvements in AOSLO autofluorescence imaging permit efficient visualization of RPE cells with safe light exposures, allowing individual characterization of RPE cell morphometry that is variable between participants. The normative dataset and analysis of RPE cell IRAF and SWAF herein are essential for understanding microscopic characteristics of cell fluorescence and may assist in interpreting disease progression in RPE cells.
Data from: The melanocortin system regulates body pigmentation and social behaviour in a colour polymorphic cichlid fish
The melanocortin system is a neuroendocrine system that regulates a range of physiological and behavioural processes. We examined the extent to which the melanocortin system simultaneously regulates colour and behaviour in the cichlid fish Astatotilapia burtoni. We found that yellow males are more aggressive than blue males, in line with previous studies. We then found that exogenous α-melanocyte-stimulating hormone (α-MSH) increases yellowness of the body and dispersal of xanthophore pigments in both morphs. However, α-MSH had a morph-specific effect on aggression, with only blue males showing an increase in the rate of aggression. Exogenous agouti signalling peptide (ASIP), a melanocortin antagonist, did not affect coloration but reduced the rate of aggression in both colour morphs. Blue males had higher cortisol levels than yellow males. Neural gene expression of melanocortin receptors (mcr) and ligands was not differentially regulated between colour morphs. In the skin, however, mc1r and pro-opiomelanocortin (pomc) β were upregulated in blue males, while asip 1 was upregulated in yellow males. The effects of α-MSH on behaviour and body coloration, combined with morph-specific regulation of the stress response and the melanocortin system, suggest that the melanocortin system contributes to the polymorphism in behaviour and coloration in A. burtoni.
Data from: Molecular analysis of caffeoyl residues related to pigmentation in green cotton fibers
The pigment components in green cotton fibers were isolated and identified as 22-O-caffeoyl-22-hydroxymonodocosanoin and 22-O-caffeoyl-22-hydroxydocosanoic acid. The concentration of 22-O-caffeoyl-22-hydroxymonodocosanoin was correlated positively with the degree of green fibers of color, indicating a role of caffeoyl derivatives in pigmentation of green cotton fibers. Upland cotton (Gossypium hirsutum L.) contains four genes (Gh4CL1 to Gh4CL4) encoding 4-coumarate:CoA ligase (4CL), key enzymes of the phenylpropanoid biosynthesis pathway. In 15 to 24 days-post anthesis fibers, the expression level of Gh4CL1 was very low, Gh4CL3 had a similar expression level between the white and green cottons, Gh4CL2 had a significantly higher expression level in the green fibers than in the white fibers, whereas Gh4CL4 seemed to have a higher expression level in the white fibers than in the green fibers. According to enzyme kinetics analysis, Gh4CL1 displayed a preference for 4-coumarate, Gh4CL3 and Gh4CL4 exhibited a somewhat low but still prominent activity towards ferulate, while Gh4CL2 had a strong preference for caffeate and ferulate. These results suggest that Gh4CL2 might be involved in the metabolism of caffeoyl residues and related to pigment biosynthesis in green cotton fibers. Our findings provide insights for understanding biochemical and molecular mechanisms of pigmentation in green cotton fibers.
Data from: Predation risk determines pigmentation phenotype in nuthatches by melanin-related gene expression effects
Pigments determine the appearance of organisms. However, pigment production can be associated to physiological constraints as in the case of pheomelanin, the sulphurated form of melanin whose synthesis in melanocytes consumes cysteine and consequently reduces the availability of glutathione (GSH) to exert antioxidant protection. Pheomelanogenesis may thus increase the susceptibility to suffer chronic oxidative stress. I investigated the possibility that environmental lability in the expression of genes regulating pheomelanogenesis protects from oxidative stress, a situation in which GSH is most required. By broadcasting adult alarm calls, I manipulated the perception of predation risk, a natural source of oxidative stress, in free-living Eurasian nuthatch Sitta europaea nestlings developing pheomelanin-pigmented flank feathers. The manipulation affected the consumption of GSH that resulted from the expression of two genes (Slc7a11 and Slc45a2) influencing cysteine/GSH availability in cells, as these genes were downregulated in the feather melanocytes of the nestlings with lowest intracellular antioxidant capacity (i.e., lowest GSH levels). Systemic oxidative damage increased with Slc7a11 expression in feather melanocytes, suggesting that the observed downregulation was physiologically advantageous. The nestlings exposed to an increased perception of predation risk developed flank feathers of reduced color intensity. These results indicate that perceived predation risk can determine the pigmentation phenotype by (probably epigenetic) effects on gene expression that protect from physiological constraints imposed by pheomelanin production.
Data from: Evolution of carotenoid pigmentation in caciques and meadowlarks (Icteridae): repeated gains of red plumage coloration by carotenoid C4-oxygenation
Many animals use carotenoid pigments to produce yellow, orange, and red coloration. In birds, at least 10 carotenoid compounds have been documented in red feathers; most of these are produced through metabolic modification of dietary precursor compounds. However, it is poorly understood how lineages have evolved the biochemical mechanisms for producing red coloration. We used high-performance liquid chromatography to identify the carotenoid compounds present in feathers from 15 species across two clades of blackbirds (the meadowlarks and allies, and the caciques and oropendolas; Icteridae), and mapped their presence or absence on a phylogeny. We found that the red plumage found in meadowlarks includes different carotenoid compounds than the red plumage found in caciques, indicating that these gains of red color are convergent. In contrast, we found that red coloration in two closely related lineages of caciques evolved twice by what appear to be similar biochemical mechanisms. The C4-oxygenation of dietary carotenoids was responsible for each observed transition from yellow to red plumage coloration, and has been commonly reported by other researchers. This suggests that the C4-oxygenation pathway may be a readily evolvable means to gain red coloration using carotenoids.
Red Pigment Test Tube
Test-tubes collected from Yaghan communities in Tierra del Fuego Source: Objaverse 1.0 / Sketchfab
White Pigment Test Tube
Test-tubes collected from Yaghan communities in Tierra del Fuego Source: Objaverse 1.0 / Sketchfab
Stressful daylight: Differences in diel rhythmicity between albino and pigmented fish
<p>In laboratory experiments, variously colored strains of animals, including those with albino phenotypes, are commonly used. The melanocortin theory suggests, however, that coloration phenotypes alter animal physiology and behavior. Animals with the albino phenotype show photoreceptor degradation associated with lowered visual accuracy, escape reactions, etc., presumably accompanied by prevailing nocturnal activity and lowered aggressiveness. This assumption was tested in small groups of albino and pigmented European catfish, Silurus glanis, during the circadian cycle. The frequency of agonistic interactions was observed during mutual contests for shelters, and subsequently, blood plasma, brain, gill, and liver samples were collected to evaluate stress parameters. In an experimental arena with shelters, the light/dark rhythmicity of locomotor activity and aggressiveness of the two phenotypes were comparable; the acrophase was observed at night, and a lower peak was observed at dawn. In an experimental stream without shelters, the acrophase of locomotor activity occurred at night for only the pigmented phenotype. In the evaluation of four antioxidants and one oxidative stress indicator, representing a total of 15 indices, albino fish showed significant rhythmicity for eight indices, whereas pigmented catfish showed significant rhythmicity for five indices. The production of blood stress parameters in the acrophase during the day occurred only in albino fish.</p> <p>A complex model was fitted with the aim of evaluating the links between behavioral and biochemical indices. Time periodicity was modeled using a sine wave and confirmed parallel courses of agonistic interactions in the catfish groups; the acrophase at dawn was associated with a 4.08-fold (conf. int. 3.53–4.7) increase in such interactions. The changes in glucose and superoxide dismutase concentrations varied with phenotype, while the effects of cortisol, lactate and catalase did not. In summary, the rhythmicity of locomotor activity and changes in the aggressiveness of catfish were influenced by shelter availability, and the effect of light-induced stress was more apparent in albino fish than in pigmented conspecific fish. The results suggested that animals with pigmentation patterns naturally occurring in the wild show more reasonable values during experiments than animals with an albino phenotype.</p>
Data from: Pigment molecular composition reveals significant information for visual communication
<p>1. Melanins are the most common pigments in vertebrates and, as such, fufill multiple adaptive functions, including honest signaling. This is the case of male pied flycatchers Ficedula hypoleuca, whose dorsal plumage, composed of black and grey feathers pigmented by eumelanin, is sexually selected by females regarding the proportion of black.</p> <p>2. However, the basis of such mating preferences and other associations with life-history traits are unknown. </p> <p>3. Here I take advantage of recent advances in Raman spectroscopy analysis to investigate the monomeric composition of eumelanin, constituted by 5,6-dihydroxyindole (DHI) and 5,6-dihydroxyindole-2-carboxylic acid (DHICA) subunits, in male pied flycatchers. </p> <p>4. I found that plumage blackness (percentage of dorsal black feathers) increases with the DHICA:DHI ratio of the constituent black freathers, but not with that of grey feathers. The repeatability of DHICA:DHI measurements in black feathers is two times that in grey feathers. </p> <p>5. Eumelanin chemistry may thus constitute the basis of signal honesty in pied flycatchers, as females preferentially mate with males with higher relative DHICA feather contents and this may be related to the lower pro-oxidant effect of DHICA. Given the the ubiquitous nature of melanin-based pigmentation phenotypes, the monomeric composition of eumelanin should therefore be considered, instead of eumelanin as a whole, for a better understanding of how and why phenotypes are linked to life-history traits in animals.</p>
◂Fig. 1 Live photos and dissection of parasitized Aphrodita longipalpa and Veneriserva pygoclava. A Ventral view of A. longipalpa. B Dorsal view of A. longipalpa with removed feltage chaetae, revealing the parasite visible through the body wall. C Ventrally dissected A. longipalpa, exposing the sizable female parasite. Veneriserva pygoclava individuals within the host are indicated by arrowheads. D Juvenile female V. pygoclava, with developing oocytes visible through the body wall along the mid-dorsal orange line. E Female V. pygoclava showing the mid-dorsal orange pigmentation and the white mark at the base of the prostomium. F Male V. pygoclava. G A large female and smaller male V. pygoclava, extracted from the same host. The pygidium is club-shaped in both males and females and juveniles. H Juvenile V. pygoclava shown from multiple angles, characterized by a complete white coloration; black jaws are magnified in panel in Hardly Venus's servant-morphological adaptations of Veneriserva to an endoparasitic lifestyle and its phylogenetic position within Dorvilleidae (Annelida)
◂Fig. 1 Live photos and dissection of parasitized Aphrodita longipalpa and Veneriserva pygoclava. A Ventral view of A. longipalpa. B Dorsal view of A. longipalpa with removed feltage chaetae, revealing the parasite visible through the body wall. C Ventrally dissected A. longipalpa, exposing the sizable female parasite. Veneriserva pygoclava individuals within the host are indicated by arrowheads. D Juvenile female V. pygoclava, with developing oocytes visible through the body wall along the mid-dorsal orange line. E Female V. pygoclava showing the mid-dorsal orange pigmentation and the white mark at the base of the prostomium. F Male V. pygoclava. G A large female and smaller male V. pygoclava, extracted from the same host. The pygidium is club-shaped in both males and females and juveniles. H Juvenile V. pygoclava shown from multiple angles, characterized by a complete white coloration; black jaws are magnified in panel
Intracellular and secreted proteome data from stressed human retinal pigmented epithelium tissues.
<p>Supporting tables for manuscript submission. </p>
Fig. 3 in The Study Of Age-Related Variability Of Pigmentation Patterns Of The Shells Of Dreissena Polymorpha (Bivalvia, Dreissenidae) From Different Parts Of It'S Range
Fig. 3. Latitudinal variability of the number of pattern types. Samples: 1–6 — the Rybinsk Reservoir; 7–10 — the Gorky Reservoir; 11 — Lake Plescheevo; 12 — the Kama Reservoir; 13 — Lake Forelevoe; 14 — Northern Dvina River; 15 — the Chograi Reservoir; 16 — RR–1 channel; 17 — Lake Sharony; 18 — Ahtuba River; 19 — Belinskiy Bank; 20 — Danube River; 21, 22 — the Perućica Reservoir; 23 — Lake Erie; 24, 25 — Lake Michigan.
Fig. 6 in The Study Of Age-Related Variability Of Pigmentation Patterns Of The Shells Of Dreissena Polymorpha (Bivalvia, Dreissenidae) From Different Parts Of It'S Range
Fig. 6. Scheme of pattern change in zebra mussel population (by the example of the Perućica Reservoir). Data for mussels of ages from 1+ to 3+ are aggregated.
Distinct melanocyte subpopulations defined by stochastic expression of proliferation or maturation programs enable a rapid and sustainable pigmentation response
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Experimental schedule for conducting the depigmenting effect of DHQ on UVB-induced pigmentation of C57/BL mice.
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Data from: Unlinked Mendelian inheritance of red and black pigmentation in snakes: implications for Batesian mimicry
Identifying the genetic basis of mimetic signals is critical to understanding both the origin and dynamics of mimicry over time. For species not amenable to large laboratory breeding studies, widespread color polymorphism across natural populations offers a powerful way to assess the relative likelihood of different genetic systems given observed phenotypic frequencies. We classified color phenotype for 2,175 ground snakes (Sonora semiannulata) across the continental United States to analyze morph ratios and test among competing hypotheses about the genetic architecture underlying red and black coloration in coral snake mimics. We found strong support for a two-locus model under simple Mendelian inheritance, with red and black pigmentation being controlled by separate loci. We found no evidence of either linkage disequilibrium between loci or sex linkage. In contrast to Batesian mimicry systems like butterflies in which all color signal components are linked into a single "supergene," our results suggest that the mimetic signal in colubrid snakes can be disrupted through simple recombination and that color evolution is likely to involve discrete gains and losses of each signal component. Both outcomes are likely to contribute to the exponential increase in rates of color evolution seen in snake mimicry systems over insect systems.
Data from: Opsins in Onychophora (velvet worms) suggest a single origin and subsequent diversification of visual pigments in arthropods
<p>Multiple visual pigments, prerequisites for color vision, are found in arthropods, but the evolutionary origin of their diversity remains obscure. In this study, we explore the opsin genes in five distantly related species of Onychophora, using deep transcriptome sequencing and screening approaches. Surprisingly, our data reveal the presence of only one opsin gene (<em>onychopsin</em>) in each onychophoran species, and our behavioral experiments indicate a maximum sensitivity of onychopsin to blue–green light. In our phylogenetic analyses, the onychopsins represent the sister group to the monophyletic clade of visual r-opsins of arthropods. These results concur with phylogenomic support for the sister-group status of the Onychophora and Arthropoda and provide evidence for monochromatic vision in velvet worms and in the last common ancestor of Onychophora and Arthropoda. We conclude that the diversification of visual pigments and color vision evolved in arthropods, along with the evolution of compound eyes—one of the most sophisticated visual systems known.</p>
Fig. 2 in Mechanisms of pigmentation loss in subterranean fishes
Fig. 2. Detail of the caudal-fin of the same specimen of Stygichthys typhlops after administration of L-DOPA; melanophores indicated by arrows. Magnification 200 x.
Green fluorescent protein-like pigments optimize the internal light environment in symbiotic reef building corals
<p>Pigments homologous to the Green Fluorescent Protein (GFP) have been proposed to fine-tune the internal light microclimate of corals, facilitating photoacclimation of photosynthetic coral symbionts (Symbiodiniaceae) to life in different reef habitats and environmental conditions. However, direct measurements of the <i>in vivo</i> light conditions inside the coral tissue supporting this conclusion are lacking. Here, we quantified the intra-tissue spectral light environment of corals expressing GFP-like proteins from widely different light regimes. We focus on (1) photoconvertible red fluorescent proteins (pcRFPs), thought to enhance photosynthesis in mesophotic habitats via wavelength conversion, and (2) chromoproteins (CPs), which provide photoprotection to the symbionts in shallow water via light absorption. Optical microsensor measurements indicated that both pigment groups strongly alter the<i> </i>coral tissue light environment. Estimates derived from light spectra measured in pcRFP-containing corals showed that fluorescence emission can contribute to >50% of orange-red light available to the photosynthetic symbionts at mesophotic depths. We further show that upregulation of pink CPs in shallow-water corals during bleaching leads to a reduction of orange light by 10-20% compared to low-CP tissue. Thus, screening by CPs has an important role in mitigating the light-enhancing effect of coral tissue scattering during bleaching. Our results provide the first experimental quantification of the importance of GFP-like proteins in fine-tuning the light microclimate of corals during photoacclimation.</p>
Figure 4 from: Frohschammer S, Seifert B (2013) Cardiocondyla pirata sp. n. – a new Philippine ant with enigmatic pigmentation pattern (Hymenoptera, Formicidae). ZooKeys 301: 13-24. https://doi.org/10.3897/zookeys.301.4913
Figure 4 - Dorsolateral aspect of a paratype gyne. Only one lobe of postpetiolar sternite is visible.
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Allen Brain Atlas
Allen Brain Atlas is an Allen Institute collection of brain map atlases, datasets, APIs, and analysis tools covering mouse, human, and non-human primate brain resources.
Annotated Behaviour and Observability Dataset (ABODe)
ABODe is a University of Edinburgh DataShare dataset for behavior classification in group-housed mice using home-cage video, identities, bounding boxes, ground-plate positions, and annotator labels.
DANDI Archive for NWB datasets
DANDI is a BRAIN Initiative archive for publishing and sharing neurophysiology data, including electrophysiology, optophysiology, and behavioral data packaged as NWB and related standards.
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The International Brain Laboratory public data releases expose standardized mouse decision-making experiments, including Neuropixels recordings, widefield calcium imaging, behavior, and session metadata accessed through the ONE API.
OpenNeuro
OpenNeuro is a free, open platform for sharing neuroimaging datasets, with public search, dataset pages, and download paths for web, S3, DataLad, and the OpenNeuro CLI.