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Seminars in Cell & Developmental Biology Feb 2009Mechanisms of animal skin pigment pattern formation have long been of interest to developmental and mathematical biologists. Although there has been a well-studied... (Review)
Review
Mechanisms of animal skin pigment pattern formation have long been of interest to developmental and mathematical biologists. Although there has been a well-studied theoretical hypothesis-the reaction-diffusion system-that is able to reproduce the variety of skin patterns, a lack of molecular evidence has kept it just a hypothesis. In this review, we summarize the results of theoretical studies to date for researchers not familiar with their mathematical underpinnings, and we discuss future approaches that will more fully integrate mathematical models and experimental analyses.
Topics: Animals; Behavior, Animal; Body Patterning; Models, Biological; Pigmentation
PubMed: 18996494
DOI: 10.1016/j.semcdb.2008.10.008 -
Journal of the Mechanical Behavior of... Aug 2022This study aims to characterize the effect of shading techniques on the fatigue behavior of a 4YSZ ceramic (4 mol% yttrium stabilized zirconia) adhesively bonded to a...
This study aims to characterize the effect of shading techniques on the fatigue behavior of a 4YSZ ceramic (4 mol% yttrium stabilized zirconia) adhesively bonded to a dentin analogue (fiber-reinforced epoxy resin). 4YSZ ceramic discs (IPS e.max ZirCAD, Ø = 10 mm and 1 mm of thickness) were allocated according to the factor 'shading technique' into 4 groups: Brush- unshaded ceramic disc (IPS e.max ZirCAD BL) pigmented at the pre-sintered stage with pigment solution applied manually using a round liner brush; Immersion- unshaded ceramic disc pigmented through immersion in the solution for 1 s on only one side of the ceramic disc; Manufacturer- specimens already shaded by the manufacturer (IPS e.max ZirCAD MT A2 - Manufacturer group); Control- a control condition with absence of pigment (i.e. non-pigmented specimens). The specimens were sintered and a spectrophotometer (SP60, EX- Rite) was used to ensure that the same perceived color (i.e. pigment saturation) was achieved in the different shading strategies (Manufacturer, Brush or Immersion groups). To do so, the color differences (ΔE) were calculated using the CIEDE 2000 equation; and an ΔE of up to 1.77 was considered as an acceptability threshold. Dentin analogue discs were obtained (Ø = 10 mm and 2.5 mm of thickness) and randomly allocated into pairs with the 4YSZ ceramic discs. Next, the pairs were adhesively bonded using a resin cement (Multilink N). The bonded assemblies (n = 15) were tested for fatigue using the step-stress test method (frequency of 20 Hz; 10,000 cycles per step, initial load 200 N; step-size of 100 N, up to 700 N; and after, step-size of 50 N, until specimen failure/fracture or radial cracks). Fatigue failure load (FFL) and number of cycles for failure (CFF) were recorded for statistical analysis. Fractographic features were accessed, and complementary roughness, topography, grain size and phase content analyses were performed. No statistical differences were observed in the fatigue behavior among the non-shaded condition (Control group - 880 N) and the shaded specimens (Manufacturer - 887 N, Brush - 820 N, and Immersion - 850 N groups; p > 0.05). However, the use of a brush shading technique induced slightly inferior fatigue mechanical behavior of the restorative set compared to the specimens already shaded by the manufacturer (p = 0.027). No differences in Weibull modulus were observed among the tested groups. The specimens pigmented by the brush technique demonstrated a rougher surface, with statistically higher Rz values, in addition to a larger grain size in comparison to all other conditions (p< 0.05). No m-phase content was identified (only t and c phases were detected). Thus, the shading techniques used to provide a Vita classic A2 shade does not negatively affect the mechanical fatigue properties of a bonded 4YSZ ceramic. However, the brush technique has detrimental effect on the fatigue behavior compared to when the ceramic was already provided in a shaded format by its manufacturer.
Topics: Ceramics; Dental Restoration, Permanent; Dental Stress Analysis; Materials Testing; Pigmentation; Surface Properties; Zirconium
PubMed: 35617820
DOI: 10.1016/j.jmbbm.2022.105270 -
Revue Belge de Medecine Dentaire 2008The pigmentation is the physiological or pathological accumulation of a pigment in a tissue. Physiological pigmentation in gingiva which is a part of masticatory mucous... (Review)
Review
The pigmentation is the physiological or pathological accumulation of a pigment in a tissue. Physiological pigmentation in gingiva which is a part of masticatory mucous membranes depends on the activity of the melanocytes. These non keratinocytic cells include the melanosoma where an endogenous pigment, the melanin, is synthesized. Quantitative or qualitative disruption of mucous pigmentation leads to the apparition of pigmented lesions. When melanocytes are directly concerned, the lesions can be of intrinsic origin, such as oral mucosa melanoma, the nevus, pigmented oral lichen planus etc. Pigmented lesions can be also of extrinsic origin caused by medicaments, dental materials, tobacco etc. In this article, gingival pigmentations are described to allow practitioner to elaborate a differential and positive diagnosis of gingival pigmented lesions and to facilitate an early detection of these lesions particularly the gingival melanoma.
Topics: Diagnosis, Differential; Gingiva; Gingival Diseases; Gingival Neoplasms; Humans; Hyperpigmentation; Melanoma; Nevus; Pigmentation
PubMed: 18754536
DOI: No ID Found -
American Journal of Physical... Nov 1975Though pigmentation has been of interest to anthropologists for a long time, its inheritance, and particularly the reasons for the incomplete correlation of skin, hair...
Though pigmentation has been of interest to anthropologists for a long time, its inheritance, and particularly the reasons for the incomplete correlation of skin, hair and eye, is poorly understood. It is suggested that this is largely due to lack of genetically plausible hypotheses. Taking into account racial and individual variation in pigment traits, and knowledge of pigmentation in other mammals, a minimum set of genetic factors for pigmentation in man is suggested. These include: (1) a set of polygenes affecting skin color only; (2) one locus for depigmentation of the eye, not affecting skin or hair, (3) one pleiotropic gene for reduction of pigment at all sites, and (4) one or more loci with multiple alleles producing blondness or rufosity of the hair in symmetrical patterns over the body.
Topics: Eye Color; Genes; Genotype; Hair Color; Humans; Phenotype; Pigmentation; Skin Pigmentation
PubMed: 1211433
DOI: 10.1002/ajpa.1330430320 -
The International Journal of... 2021The adaptive role of amphibian oocyte melanic pigmentation and its molecular control are still elusive. Here we present evidence of a polymorphism in egg pigmentation in...
The adaptive role of amphibian oocyte melanic pigmentation and its molecular control are still elusive. Here we present evidence of a polymorphism in egg pigmentation in the emerald glass frog . In Ecuadorian natural populations of this species, females can lay dark brown or pale eggs that develop into normal pigmented tadpoles and adults. This trait is a sex-limited phenotype which is inherited like a recessive allele that we called . The phenotype is exclusive of oocyte cortical melanic pigmentation, which is reduced in comparison to wild type dark pigmented oocytes. Consequently, early embryos are paler in appearance, with reduced melanic pigmentation distributed to early blastomeres and embryonic ectoderm. However, these embryos form normal melanocyte derived pigmentation. Finally, we discuss the origin of this polymorphism and propose the use of as a model to study the adaptive role of egg pigmentation.
Topics: Animals; Anura; Blastomeres; Female; Oocytes; Phenotype; Pigmentation
PubMed: 32930380
DOI: 10.1387/ijdb.200074ar -
Journal of Experimental Botany Aug 2019Flavonoids are plant pigments that provide health benefits for human and animal consumers. Understanding why domesticated crops have altered pigmentation patterns and...
Flavonoids are plant pigments that provide health benefits for human and animal consumers. Understanding why domesticated crops have altered pigmentation patterns and unraveling the molecular/genetic mechanisms that underlie this will facilitate the breeding of new (healthier) varieties. We present an overview of changes in flavonoid pigmentation patterns that have occurred during crop domestication and, where possible, link them to the molecular changes that brought about the new phenotypes. We consider species that lost flavonoid pigmentation in the edible part of the plant at some point during domestication (like cereals). We also consider the converse situation, for example eggplant (aubergine), which instead gained strong anthocyanin accumulation in the skin of the fruit during domestication, and some varieties of citrus and apple that acquired anthocyanins in the fruit flesh. Interestingly, the genes responsible for such changes are sometimes closely linked to, or have pleiotropic effects on, important domestication genes, suggesting accidental and perhaps inevitable changes of anthocyanin patterning during domestication. In other cases, flavonoid pigmentation patterns in domesticated crops are the result of cultural preferences, with examples being found in varieties of citrus, barley, wheat, and maize. Finally, and more recently, in some species, anthocyanins seem to have been the direct target of selection in a second wave of domestication that followed the introduction of industrial food processing.
Topics: Crops, Agricultural; Domestication; Flavonoids; Genetic Linkage; Genetic Pleiotropy; Pigmentation
PubMed: 30949670
DOI: 10.1093/jxb/erz141 -
Trends in Ecology & Evolution Apr 2020Mammalian colors and color patterns are some of the most diverse and conspicuous traits found in nature and have been widely studied from genetic/developmental and... (Review)
Review
Mammalian colors and color patterns are some of the most diverse and conspicuous traits found in nature and have been widely studied from genetic/developmental and evolutionary perspectives. In this review we first discuss the proximate causes underlying variation in pigment type (i.e., color) and pigment distribution (i.e., color pattern) and highlight both processes as having a distinct developmental basis. Then, using multiple examples, we discuss ultimate factors that have driven the evolution of coloration differences in mammals, which include background matching, intra- and interspecific signaling, and physiological influences. Throughout, we outline bridges between developmental and functional investigatory approaches that help broaden knowledge of mammals' memorable external appearances, and we point out areas for future interdisciplinary research.
Topics: Animals; Biological Evolution; Color; Mammals; Phenotype; Pigmentation
PubMed: 31980234
DOI: 10.1016/j.tree.2019.12.008 -
Integrative and Comparative Biology Oct 2021Human skin and hair pigmentation play important roles in social behavior but also in photoprotection from the harmful effects of ultraviolet light. The main pigments in...
Human skin and hair pigmentation play important roles in social behavior but also in photoprotection from the harmful effects of ultraviolet light. The main pigments in mammalian skin, the melanins, are synthesized within specialized organelles called melanosomes in melanocytes, which sit at the basal layer of the epidermis and the hair bulb. The melanins are then transferred from melanocytes to keratinocytes, where they accumulate perinuclearly in membrane-bound organelles as a "cap" above the nucleus. The mechanism of transfer, the nature of the pigmented organelles within keratinocytes, and the mechanism governing their intracellular positioning are all debated and poorly understood, but likely play an important role in the photoprotective properties of melanin in the skin. Here, we detail our current understanding of these processes and present a guideline for future experimentation in this area.
Topics: Animals; Humans; Keratinocytes; Melanins; Melanocytes; Melanosomes; Pigmentation; Skin Pigmentation
PubMed: 34021340
DOI: 10.1093/icb/icab094 -
Seminars in Cell & Developmental Biology Feb 2009Insect pigmentation is a premier model system in evolutionary and developmental biology. It has been at the heart of classical studies as well as recent breakthroughs.... (Review)
Review
Insect pigmentation is a premier model system in evolutionary and developmental biology. It has been at the heart of classical studies as well as recent breakthroughs. In insects, pigments are produced by epidermal cells through a developmental process that includes pigment patterning and synthesis. Many aspects of this process also impact other phenotypes, including behavior and immunity. This review discusses recent work on the development and evolution of insect pigmentation, with a focus on pleiotropy and its effects on color pattern diversification.
Topics: Animals; Behavior, Animal; Biological Evolution; Insecta; Pigmentation
PubMed: 18977308
DOI: 10.1016/j.semcdb.2008.10.002 -
Acta Ophthalmologica Jun 2022To compare the refractive outcome and residual accommodation with respect to various degrees of iris and skin pigmentation in hypermetropic children using 2 drops of... (Randomized Controlled Trial)
Randomized Controlled Trial
Eye colour and skin pigmentation as significant factors for refractive outcome and residual accommodation in hypermetropic children: a randomized clinical trial using cyclopentolate 1% and tropicamide 1.
PURPOSE
To compare the refractive outcome and residual accommodation with respect to various degrees of iris and skin pigmentation in hypermetropic children using 2 drops of cyclopentolate 1% (C + C) or 1 drop of cyclopentolate 1% and 1 drop of tropicamide 1% (C + T).
METHODS
Two hundred fifty-one hypermetropic children were classified according to iris and skin pigmentation (light, medium, dark) and received randomized and double-blind C + C or C + T. Refractive error (spherical equivalent, SEQ) was determined using the Retinomax-K + 3. In 204 subjects, residual accommodation (RA) was determined using the PlusoptiX PowerRefractor.
RESULTS
A linear mixed model with a light-irided and light skin-pigmented reference group receiving C + T (mean SEQ +3.10 ± 1.87D) indicated significant less hypermetropia in subjects with a dark iris having a medium- and dark-pigmented skin in C + T, -1.02 ± 0.29 (-1.59/-0.45) and -1.53 ± 0.30 (-2.10/-0.95); and in subjects having a light-, medium- and dark-pigmented skin in C + C, -0.74 ± 0.34 (-1.41/-0.06), -1.26 ± 0.30 (-1.85/-0.66) and -1.84 ± 0.30 (-2.42/-1.26). Similar findings were present for RA. Our model with a light-irided and light skin-pigmented reference group receiving C + T (mean RA +0.84 ± 0.61D) indicated significantly higher RA in dark-irided subjects with medium- and dark-pigmented skin in C + T, +1.05 ± 0.19 (+0.67/+1.43) and +1.35 ± 0.20 (+0.9/+1.74), and in C + C, +1.13 ± 0.21 (+0.71/+1.55) and +1.90 ± 0.19 (+1.51/+2.28).
CONCLUSIONS
We found solid evidence that skin pigmentation rather than iris pigmentation is the decisive factor for effectiveness of cycloplegics. Awareness of the limitations of cycloplegic regimens in dark-irided/pigmented children is needed. Our study showed that cyclopentolate 1% combined with tropicamide 1% provides more accurate refractive outcomes both statistically and clinically integrating the factor skin pigmentation for dark-irided subjects.
Topics: Child; Cyclopentolate; Eye Color; Humans; Mydriatics; Ophthalmic Solutions; Skin Pigmentation; Tropicamide
PubMed: 34672100
DOI: 10.1111/aos.15016