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The New Phytologist Oct 2019Within the angiosperm order Caryophyllales, an unusual class of pigments known as betalains can replace the otherwise ubiquitous anthocyanins. In contrast to the... (Review)
Review
Within the angiosperm order Caryophyllales, an unusual class of pigments known as betalains can replace the otherwise ubiquitous anthocyanins. In contrast to the phenylalanine-derived anthocyanins, betalains are tyrosine-derived pigments which contain the chromophore betalamic acid. The origin of betalain pigments within Caryophyllales and their mutual exclusion with anthocyanin pigments have been the subject of considerable research. In recent years, numerous discoveries, accelerated by -omic scale data, phylogenetics and synthetic biology, have shed light on the evolution of the betalain biosynthetic pathway in Caryophyllales. These advances include the elucidation of the biosynthetic steps in the betalain pathway, identification of transcriptional regulators of betalain synthesis, resolution of the phylogenetic history of key genes, and insight into a role for modulation of primary metabolism in betalain synthesis. Here we review how molecular genetics have advanced our understanding of the betalain biosynthetic pathway, and discuss the impact of phylogenetics in revealing its evolutionary history. In light of these insights, we explore our new understanding of the origin of betalains, the mutual exclusion of betalains and anthocyanins, and the homoplastic distribution of betalain pigmentation within Caryophyllales. We conclude with a speculative conceptual model for the stepwise emergence of betalain pigmentation.
Topics: Betalains; Biological Evolution; Biosynthetic Pathways; Caryophyllales; Phylogeny; Pigmentation
PubMed: 31172524
DOI: 10.1111/nph.15980 -
Bio Systems Aug 2023We have reviewed and interpreted the thermodynamic principles for flower pigmentation. The basic thoughts are as follows: 1) any biological trait is associated with one...
We have reviewed and interpreted the thermodynamic principles for flower pigmentation. The basic thoughts are as follows: 1) any biological trait is associated with one thermodynamic system; 2) a thermodynamic system of biology cannot be physically isolated from complex thermal systems of biology but can be separately studied using thermodynamic methods; 3) a thermodynamic system of biology has all types of information, including volume, shape, and structure, unlike the traditional thermal system of gases; 4) a thermodynamic system of biology is associated with one type of biological structure that is not fully fixed but can change its conformation under different conditions; and 5) a thermodynamic system of biology shows a hierarchical structure. On the basis of these principles, several conclusions regarding flower pigmentation are obtained as follows: 1) processes of pigmentation formation can be divided into reversible and irreversible processes; 2) the reversible process is related to quantitative changes in pigments; 3) the irreversible process is related to the formation of stable pigmentation patterns that are physiologically inherited; 4) the spot pattern of color pigmentation represents an independent island of the physiological system; 5) many types of activators and inhibitors are involved in flower pigmentation production; 6) the patterns of flower pigmentation can be modulated; and 7) the evolution mechanism of organogenesis can be separated into several steps of independent thermodynamic processes. Our conclusion is that the thermodynamic system, rather than the dynamic system, is the essential and fundamental attribute of biological behaviors.
Topics: Pigmentation; Flowers; Phenotype; Thermodynamics
PubMed: 37277021
DOI: 10.1016/j.biosystems.2023.104938 -
Biology Letters Aug 2021Pterins are one of the major sources of bright coloration in animals. They are produced endogenously, participate in vital physiological processes and serve a variety of...
Pterins are one of the major sources of bright coloration in animals. They are produced endogenously, participate in vital physiological processes and serve a variety of signalling functions. Despite their ubiquity in nature, pterin-based pigmentation has received little attention when compared to other major pigment classes. Here, we summarize major aspects relating to pterin pigmentation in animals, from its long history of research to recent genomic studies on the molecular mechanisms underlying its evolution. We argue that pterins have intermediate characteristics (endogenously produced, typically bright) between two well-studied pigment types, melanins (endogenously produced, typically cryptic) and carotenoids (dietary uptake, typically bright), providing unique opportunities to address general questions about the biology of coloration, from the mechanisms that determine how different types of pigmentation evolve to discussions on honest signalling hypotheses. Crucial gaps persist in our knowledge on the molecular basis underlying the production and deposition of pterins. We thus highlight the need for functional studies on systems amenable for laboratory manipulation, but also on systems that exhibit natural variation in pterin pigmentation. The wealth of potential model species, coupled with recent technological and analytical advances, make this a promising time to advance research on pterin-based pigmentation in animals.
Topics: Animals; Carotenoids; Pigmentation; Pterins
PubMed: 34403644
DOI: 10.1098/rsbl.2021.0221 -
Methods in Molecular Biology (Clifton,... 2023The ommochrome and porphyrin body pigments that give freshwater planarians their brown color are produced by specialized dendritic cells located just beneath the...
The ommochrome and porphyrin body pigments that give freshwater planarians their brown color are produced by specialized dendritic cells located just beneath the epidermis. During embryonic development and regeneration, differentiation of new pigment cells gradually darkens newly formed tissue. Conversely, prolonged light exposure ablates pigment cells through a porphyrin-based mechanism similar to the one that causes light sensitivity in rare human disorders called porphyrias. Here, we describe a novel program using image-processing algorithms to quantify relative pigment levels in live animals and apply this program to analyze changes in bodily pigmentation induced by light exposure. This tool will facilitate further characterization of genetic pathways that affect pigment cell differentiation, ommochrome and porphyrin biosynthesis, and porphyrin-based photosensitivity.
Topics: Animals; Humans; Planarians; Pigmentation; Phenothiazines; Porphyrins
PubMed: 37428383
DOI: 10.1007/978-1-0716-3275-8_16 -
Journal of the Royal Society, Interface Jul 2023Many of the world's 10 000 bird species lay coloured or patterned eggs. The large diversity of eggshell patterning among birds, achieved through pigment, has been...
Many of the world's 10 000 bird species lay coloured or patterned eggs. The large diversity of eggshell patterning among birds, achieved through pigment, has been attributed to a few selective agents such as crypsis, thermoregulation, egg recognition, mate signalling, egg strength and protecting the embryo from UV. Pigmentation may influence the texture of eggshells, which in turn may be important for dealing with water and microbes. We measured surface roughness (, nm), surface skewness () and surface kurtosis (), which describe different aspects of surface texture, across 204 bird species with maculated (patterned) eggs and 166 species with immaculate (non-patterned) eggs. Using phylogenetically controlled analyses, we tested whether maculated eggshells have different surface topography between the foreground colour and background colour, and between the background colour of maculated eggshells and the surface of immaculate eggshells. Secondly, we determined to what extent variation in eggshell pigmentation of the foreground and background colour is determined by phylogenetic relatedness, and whether certain life-history traits are important predictors of eggshell surface structure. We show that the surface of maculated eggs consists of a rougher foreground pigment compared to the background pigment across 71% of the 204 bird species (54 families) investigated. Species that lay immaculate eggs showed no difference in surface roughness, kurtosis or skewness compared to background pigment of maculated eggs. The difference in eggshell surface roughness between foreground and background pigmentation was greater among species that occupied dense habitats, such as forests with closed canopies, compared to those that nest in open and semi-open habitats (e.g. cities, deserts, grasslands, open shrubland and seashores). Among maculated eggs, foreground texture was correlated with habitat, parental care, diet, nest location, avian group and nest type, while background texture was correlated with clutch size, annual temperature, development mode and annual precipitation. Surface roughness among immaculate eggs was greatest for herbivores, and species that have larger clutch sizes. Together, this suggests that multiple life-history traits have influenced the evolution of eggshell surface textures in modern birds.
Topics: Animals; Birds; Body Temperature Regulation; Egg Shell; Phylogeny; Pigmentation
PubMed: 37434502
DOI: 10.1098/rsif.2023.0293 -
Medicina Oral, Patologia Oral Y Cirugia... May 2022The diagnosis of oral melanotic lesions is, more often than not, challenging in the clinical practice due to the fact that there are several reasons which may cause an... (Review)
Review
BACKGROUND
The diagnosis of oral melanotic lesions is, more often than not, challenging in the clinical practice due to the fact that there are several reasons which may cause an increase in pigmentation on localized or generalized areas. Among these, medication stands out.
MATERIAL AND METHODS
In this work, we have carried out a review in the reference pharma database: Micromedex® followed by a review of the scientific published literature to analyse coincidences and possible discrepancies.
RESULTS
Our findings show that there are several prescription drugs that can cause pigmented lesions in the oral mucosa. This must be known by clinicians in order to properly diagnose pigmented lesions. We have identified a set of 21 medicaments which cause these lesions, some of which are used frequently in the clinic, such as Metronidazole, Amitriptyline, conjugated oestrogens and Chlorhexidine gluconate. We also found discrepancies with the data published in specialized literature, some of which wasn't reflected in the Summary of Product Characteristics.
CONCLUSIONS
Our work highlights the importance of the proper communication of adverse drug reactions (ADR) by health professionals in order to provide thorough and accurate information and diagnosis.
Topics: Humans; Mouth Mucosa; Oral Ulcer; Pigmentation
PubMed: 35420067
DOI: 10.4317/medoral.25110 -
International Journal of Molecular... Apr 2021The production of melanin pigments by melanocytes and their quantity, quality, and distribution play a decisive role in determining human skin, eye, and hair color, and... (Review)
Review
The production of melanin pigments by melanocytes and their quantity, quality, and distribution play a decisive role in determining human skin, eye, and hair color, and protect the skin from adverse effects of ultraviolet radiation (UVR) and oxidative stress from various environmental pollutants. Melanocytes reside in the basal layer of the interfollicular epidermis and are compensated by melanocyte stem cells in the follicular bulge area. Various stimuli such as eczema, microbial infection, ultraviolet light exposure, mechanical injury, and aging provoke skin inflammation. These acute or chronic inflammatory responses cause inflammatory cytokine production from epidermal keratinocytes as well as dermal fibroblasts and other cells, which in turn stimulate melanocytes, often resulting in skin pigmentation. It is confirmed by some recent studies that several interleukins (ILs) and other inflammatory mediators modulate the proliferation and differentiation of human epidermal melanocytes and also promote or inhibit expression of melanogenesis-related gene expression directly or indirectly, thereby participating in regulation of skin pigmentation. Understanding of mechanisms of skin pigmentation due to inflammation helps to elucidate the relationship between inflammation and skin pigmentation regulation and can guide development of new therapeutic pathways for treating pigmented dermatosis. This review covers the mechanistic aspects of skin pigmentation caused by inflammation.
Topics: Aging; Cell Differentiation; Humans; Inflammation; Keratinocytes; Melanins; Melanocytes; Skin; Skin Pigmentation; Ultraviolet Rays
PubMed: 33921371
DOI: 10.3390/ijms22083970 -
Annals of Botany Nov 2022Land plants commonly produce red pigmentation as a response to environmental stressors, both abiotic and biotic. The type of pigment produced varies among different land... (Review)
Review
BACKGROUND
Land plants commonly produce red pigmentation as a response to environmental stressors, both abiotic and biotic. The type of pigment produced varies among different land plant lineages. In the majority of species they are flavonoids, a large branch of the phenylpropanoid pathway. Flavonoids that can confer red colours include 3-hydroxyanthocyanins, 3-deoxyanthocyanins, sphagnorubins and auronidins, which are the predominant red pigments in flowering plants, ferns, mosses and liverworts, respectively. However, some flowering plants have lost the capacity for anthocyanin biosynthesis and produce nitrogen-containing betalain pigments instead. Some terrestrial algal species also produce red pigmentation as an abiotic stress response, and these include both carotenoid and phenolic pigments.
SCOPE
In this review, we examine: which environmental triggers induce red pigmentation in non-reproductive tissues; theories on the functions of stress-induced pigmentation; the evolution of the biosynthetic pathways; and structure-function aspects of different pigment types. We also compare data on stress-induced pigmentation in land plants with those for terrestrial algae, and discuss possible explanations for the lack of red pigmentation in the hornwort lineage of land plants.
CONCLUSIONS
The evidence suggests that pigment biosynthetic pathways have evolved numerous times in land plants to provide compounds that have red colour to screen damaging photosynthetically active radiation but that also have secondary functions that provide specific benefits to the particular land plant lineage.
Topics: Anthocyanins; Embryophyta; Pigmentation; Betalains; Plants; Flavonoids
PubMed: 36070407
DOI: 10.1093/aob/mcac109 -
American Journal of Physiology.... Sep 2019The vitamin D-folate hypothesis has been proposed as an explanation for the evolution of human skin pigmentation. According to this hypothesis, a darkened skin pigment... (Review)
Review
The vitamin D-folate hypothesis has been proposed as an explanation for the evolution of human skin pigmentation. According to this hypothesis, a darkened skin pigment was adapted by early human populations living in equatorial Africa to protect against photodegradation of bioavailable folate by ultraviolet radiation (UVR). As humans moved away from the equator to more northern latitudes and occupied regions of lower UVR exposure and greater seasonal variation, however, depigmentation occurred to allow for adequate biosynthesis of vitamin D. Vitamin D and folate are both recognized for their evolutionary importance in healthy pregnancy and early childhood development. More recently, evidence has emerged demonstrating the importance of both vitamin D and folate in vascular health via their effects in reducing oxidative stress and improving nitric oxide (NO) bioavailability. Thus, populations with darkened skin pigmentation may be at elevated risk of vascular dysfunction and cardiovascular disease in low UVR environments due to hypovitaminosis D; particularly important as darkly-pigmented African-Americans represent an at-risk population for cardiovascular disease. Conversely, lightly pigmented populations in high UVR environments may be at risk of deleterious vascular effects of UVR-induced folate degradation. The focus of this review is to explore the currently available literature regarding the potential role of UVR in vascular health via its differential effects on vitamin D and folate metabolism, as well as the interaction between skin pigmentation, genetics, and environment in modulating the vascular influence of UVR exposure.
Topics: Biological Evolution; Cardiovascular Diseases; Folic Acid; Humans; Skin Pigmentation; Ultraviolet Rays; Vitamin D
PubMed: 31314544
DOI: 10.1152/ajpregu.00136.2019 -
Development, Growth & Differentiation Jun 2020Fruit flies (Drosophila and its close relatives, or "drosophilids") are a group that includes an important model organism, Drosophila melanogaster, and also very diverse... (Review)
Review
Fruit flies (Drosophila and its close relatives, or "drosophilids") are a group that includes an important model organism, Drosophila melanogaster, and also very diverse species distributed worldwide. Many of these species have black or brown pigmentation patterns on their wings, and have been used as material for evo-devo research. Pigmentation patterns are thought to have evolved rapidly compared with body plans or body shapes; hence they are advantageous model systems for studying evolutionary gains of traits and parallel evolution. Various groups of drosophilids, including genus Idiomyia (Hawaiian Drosophila), have a variety of pigmentations, ranging from simple black pigmentations around crossveins to a single antero-distal spot and a more complex mottled pattern. Pigmentation patterns are sometimes obviously used for sexual displays; however, in some cases they may have other functions. The process of wing formation in Drosophila, the general mechanism of pigmentation formation, and the transport of substances necessary for pigmentation, including melanin precursors, through wing veins are summarized here. Lastly, the evolution of the expression of genes regulating pigmentation patterns, the role of cis-regulatory regions, and the conditions required for the evolutionary emergence of pigmentation patterns are discussed. Future prospects for research on the evolution of wing pigmentation pattern formation in drosophilids are presented, particularly from the point of view of how they compare with other studies of the evolution of new traits.
Topics: Animals; Biological Evolution; Drosophila melanogaster; Gene Expression Regulation, Developmental; Pigmentation; Wings, Animal
PubMed: 32171022
DOI: 10.1111/dgd.12661