-
Oral Health & Preventive Dentistry Aug 2023The present study aimed to observe the anatomical distribution of gingival melanin pigmentation and evaluate its intensity and extent in different age groups and in...
PURPOSE
The present study aimed to observe the anatomical distribution of gingival melanin pigmentation and evaluate its intensity and extent in different age groups and in correlation with skin and tooth shades.
MATERIALS AND METHODS
The participants of this study were 391 patients attending the Dental University Hospital. The presence of gingival pigmentation was assessed using De Krom's Oral Pigmentation Chart and its intensity was assessed using the Dummett-Gupta Oral Pigmentation Index. Skin colour and tooth shade were measured using the Fitzpatrick scale and the VITA classical shade guide, respectively. Statistical analyses included descriptive statistics and Pearson's Χ2 test for the association between the study variables.
RESULTS
The prevalence of gingival pigmentation among the sample size was 74.4%, and pigmentations were present on both arches in 57.6% (n = 224) of the participants. The extent (category 1) was highest when pigmentation was evident in both arches, with category 4 being the least extent. Age and sex did not show a correlation with gingival pigmentation. Gingival pigmentation intensity was mild when pigments were present in one arch (p < 0.00), whereas it was heavy when both arches presented with gingival pigmentation. Medium brown colour and tooth shade A1 were the most common among participants with gingival pigmentation (p < 0.00). The association between gingival pigmentation intensity and extent in relation to skin colour was statistically significant (p < 0.00), as was tooth shade (p < 0.05).
CONCLUSIONS
Gingival pigmentation is highly prevalent in the Saudi population, with different severity and extent levels. The effect of gingival pigmentation on smile and overall facial aesthetics should be considered when providing dental and cosmetic treatments.
Topics: Humans; Cross-Sectional Studies; Saudi Arabia; Pigmentation
PubMed: 37724898
DOI: 10.3290/j.ohpd.b4347777 -
BMC Research Notes Feb 2020The golden color of Staphylococcus aureus is due to the synthesis of carotenoid pigments. In Gram-negative bacteria, Hfq is a global posttranscriptional regulator, but...
OBJECTIVE
The golden color of Staphylococcus aureus is due to the synthesis of carotenoid pigments. In Gram-negative bacteria, Hfq is a global posttranscriptional regulator, but its function in S. aureus remains obscure. The absence of Hfq in S. aureus was reported to correlate with production of carotenoid pigment leading to the conclusion that Hfq was a negative regulator of the yellow color. However, we reported the construction of hfq mutants in several S. aureus strains and never noticed any color change; we therefore revisited the question of Hfq implication in S. aureus pigmentation.
RESULTS
The absence or accumulation of Hfq does not affect S. aureus pigmentation.
Topics: Gene Expression Regulation, Bacterial; Host Factor 1 Protein; Pigmentation; Staphylococcus aureus
PubMed: 32033621
DOI: 10.1186/s13104-020-4934-4 -
Heredity Sep 2006The study of pigmentation has played an important role in the intersection of evolution, genetics, and developmental biology. Pigmentation's utility as a visible... (Review)
Review
The study of pigmentation has played an important role in the intersection of evolution, genetics, and developmental biology. Pigmentation's utility as a visible phenotypic marker has resulted in over 100 years of intense study of coat color mutations in laboratory mice, thereby creating an impressive list of candidate genes and an understanding of the developmental mechanisms responsible for the phenotypic effects. Variation in color and pigment patterning has also served as the focus of many classic studies of naturally occurring phenotypic variation in a wide variety of vertebrates, providing some of the most compelling cases for parallel and convergent evolution. Thus, the pigmentation model system holds much promise for understanding the nature of adaptation by linking genetic changes to variation in fitness-related traits. Here, I first discuss the historical role of pigmentation in genetics, development and evolutionary biology. I then discuss recent empirically based studies in vertebrates, which rely on these historical foundations to make connections between genotype and phenotype for ecologically important pigmentation traits. These studies provide insight into the evolutionary process by uncovering the genetic basis of adaptive traits and addressing such long-standing questions in evolutionary biology as (1) are adaptive changes predominantly caused by mutations in regulatory regions or coding regions? (2) is adaptation driven by the fixation of dominant mutations? and (3) to what extent are parallel phenotypic changes caused by similar genetic changes? It is clear that coloration has much to teach us about the molecular basis of organismal diversity, adaptation and the evolutionary process.
Topics: Adaptation, Biological; Animals; Biological Evolution; Evolution, Molecular; Gene Expression Regulation, Developmental; Genetic Variation; Mice; Pigmentation; Vertebrates
PubMed: 16823403
DOI: 10.1038/sj.hdy.6800861 -
G3 (Bethesda, Md.) Dec 2023The US standard for maize commercially grown for grain specifies that yellow corn can contain at maximum 5% corn of other colors. Inbred parents of commercial hybrids...
The US standard for maize commercially grown for grain specifies that yellow corn can contain at maximum 5% corn of other colors. Inbred parents of commercial hybrids typically have clear pericarp, but transgressive segregants in breeding populations can display variation in pericarp pigmentation. We identified 10 doubled haploid biparental populations segregating for pigmented pericarp and evaluated qualitative genetic models using chi-square tests of observed and expected frequencies. Pigmentation ranged from light to dark brown color, and pigmentation intensity was quantitatively measured across 1,327 inbred lines using hue calculated from RGB pixel values. Genetic mapping was used to identify loci associated with pigmentation intensity. For 9 populations, pigmentation inheritance best fit a hypothesis of a 2- or 3-gene epistatic model. Significant differences in pigment intensity were observed across populations. W606S-derived inbred lines with the darkest pericarp often had clear glumes, suggesting the presence of a novel P1-rw allele, a hypothesis supported by a significant quantitative trait locus peak at P1. A separate quantitative trait locus region on chromosome 2 between 221.64 and 226.66 Mbp was identified in LH82-derived populations, and the peak near p1 was absent. A genome-wide association study using 416 inbred lines from the Wisconsin Diversity panel with full genome resequencing revealed 4 significant associations including the region near P1. This study supports that pericarp pigmentation among dent maize inbreds can arise by transgressive segregation when pigmentation in the parental generation is absent and is partially explained by functional allelic variation at the P1 locus.
Topics: Zea mays; Genes, Plant; Genome-Wide Association Study; Plant Breeding; Pigmentation
PubMed: 37950891
DOI: 10.1093/g3journal/jkad256 -
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 -
Pigment Cell Research 1989There has been great interest lately in the cloning of pigment-related genes; several laboratories have succeeded in isolating melanocyte-specific genes which have many... (Review)
Review
There has been great interest lately in the cloning of pigment-related genes; several laboratories have succeeded in isolating melanocyte-specific genes which have many of the characteristics expected for tyrosinase. In this paper, we review the selection criteria, the physical properties, and the functional characteristics of several of these gene products. Two of the clones map to the brown (b) and albino (c) loci, genes that are involved in the regulation of the quantity and quality of melanin production. The functional characteristics of these gene products are not easily reconciled with existing schemes of melanogenesis, and a reevaluation of our concepts of melanogenic regulation may be necessary. The altered expression of these gene products in normal and in transformed melanocytes, and the alternative mRNA processing that occurs in those cells, makes this system an appropriate and interesting one for studies of normal metabolic regulation of gene expression, as well as altered gene expression by neoplastic cells.
Topics: Animals; Melanins; Mice; Monophenol Monooxygenase; Phenotype; Pigmentation; Pigments, Biological
PubMed: 2497450
DOI: 10.1111/j.1600-0749.1989.tb00166.x -
Veterinary Dermatology Dec 2007Coat colours in cattle have been of interest to both breeders and researchers as genes regulating pigmentation not only affect the phenotype but also have economic... (Review)
Review
Coat colours in cattle have been of interest to both breeders and researchers as genes regulating pigmentation not only affect the phenotype but also have economic implications in the event of genetic mutations. The genes controlling pigmentation act as a complex and interact with each other to cause phenotypic and genotypic variations. Pigmentation of coat broadly depends on the ratio of eumelanin and pheomelanin, the two components of melanin. Increase in eumelanin imparts a black coat colour while raise in pheomelanin is responsible for a yellowish or reddish colour. The main enzymes responsible for melanogenesis are regulated by the genes of the tyrosinase family. It is speculated that the wild-type gene present in the ancestral breeds of the present day cattle have more pheomelanin content and that, over time, mutations have introduced more variations leading to many shades. This could have occurred either because of interactions or because of deletions in the responsible genes. The environmental conditions have also contributed to mutations in these genes, helping in the adaptability of the animals to different geographical regions. The switching between the syntheses of melanin components depends on several genes like melanocortin-1receptor gene (MC1r) - also known as melanocyte-stimulating hormone receptor gene (MSHr)-, agouti (A), attractin (Atrn) and mahogunin (Mgrn1). The purpose of this review is to summarize the recent advances in the field of pigment biology and to highlight possible areas of research that may benefit a breeder or a farmer in the selection of animals on the basis of phenotype.
Topics: Animals; Cattle; Genetic Variation; Hair Color; Phenotype
PubMed: 17991156
DOI: 10.1111/j.1365-3164.2007.00634.x -
Dental Materials : Official Publication... Dec 2022To characterize the effect of pigmentation techniques on the fatigue behavior of a 4YSZ ceramic adhesively luted onto dentin analog (glass fiber-reinforced epoxy resin).
OBJECTIVE
To characterize the effect of pigmentation techniques on the fatigue behavior of a 4YSZ ceramic adhesively luted onto dentin analog (glass fiber-reinforced epoxy resin).
METHODS
4YSZ ceramic discs (Ø= 10 mm, 1 mm thickness) were allocated into 5 groups: Ctrl - unshaded (IPS e.max ZirCAD MT BL); Manuf - shaded by the manufacturer (IPS e.max ZirCAD MT A2); Brush - unshaded pigmented, pre-sintering, using a brush; Stain - unshaded pigmented, post-sintering, during glaze application; Brush+Stain - combination of both techniques. Color assessments ensured the same perceived color (Vita Classical A2). Dentin analog discs (Ø= 10 mm, 2.5 mm thickness) were obtained, paired with the 4YSZ discs, and adhesively luted using a resin cement. Cyclic fatigue testing (n = 15) was run (20 Hz; 10,000 cycles/step, initial load 200 N; step-size 100 N up to 700 N; then 50 N until specimen failure). Fractographic, roughness and topography analyses were performed.
RESULTS
No statistical (p > 0.05) detrimental influence were observed for fatigue outcomes (Ctrl = Manuf = Brush = Stain = Brush+Stain). However, the Brush+Stain technique induced inferior statistical (p < 0.05) fatigue performance compared to Stain. All failures were radial cracks with origin at the ceramic intaglio surface. The staining technique triggered statistically higher roughness (p < 0.05). Uniformly sized zirconia crystals were seen in the Ctrl, Manuf and Brush groups, and a smooth vitreous surface with encrusted pigments in the Stain and Brush+Stain groups.
SIGNIFICANCE
Pigmentation techniques (Vita Classical A2 shade) have no detrimental effect on the mechanical fatigue properties of 4YSZ ceramic adhesively luted onto dentin analog.
Topics: Pigmentation; Ceramics; Coloring Agents; Resin Cements; Dentin
PubMed: 36424207
DOI: 10.1016/j.dental.2022.11.017 -
Genetics May 2022Pigmentation in insects has been linked to mate selection and predator evasion, thus representing an important aspect for natural selection. Insect body color is...
Pigmentation in insects has been linked to mate selection and predator evasion, thus representing an important aspect for natural selection. Insect body color is classically associated to the activity of tyrosine pathway enzymes, and eye color to pigment synthesis through the tryptophan and guanine pathways, and their transport by ATP-binding cassette proteins. Among the hemiptera, the genetic basis for pigmentation in kissing bugs such as Rhodnius prolixus, that transmit Chagas disease to humans, has not been addressed. Here, we report the functional analysis of R. prolixus eye and cuticle pigmentation genes. Consistent with data for most insect clades, we show that knockdown for yellow results in a yellow cuticle, while scarlet and cinnabar knockdowns display red eyes as well as cuticle phenotypes. In addition, tyrosine pathway aaNATpreto knockdown resulted in a striking dark cuticle that displays no color pattern or UV reflectance. In contrast, knockdown of ebony and tan, that encode N-beta-alanyl dopamine hydroxylase branch tyrosine pathway enzymes, did not generate the expected dark and light brown phenotypes, respectively, as reported for other insects. We hypothesize that R. prolixus, which requires tyrosine pathway enzymes for detoxification from the blood diet, evolved an unusual strategy for cuticle pigmentation based on the preferential use of a color erasing function of the aaNATpreto tyrosine pathway branch. We also show that genes classically involved in the generation and transport of eye pigments regulate red body color in R. prolixus. This is the first systematic approach to identify the genes responsible for the generation of color in a blood-feeding hemiptera, providing potential visible markers for future transgenesis.
Topics: Animals; Pigmentation; Rhodnius; Tyrosine
PubMed: 35445704
DOI: 10.1093/genetics/iyac064 -
Journal of Visualized Experiments : JoVE Mar 2022Melanocytes are specialized neural crest-derived cells present in the epidermal skin. These cells synthesize melanin pigment that protects the genome from harmful...
Melanocytes are specialized neural crest-derived cells present in the epidermal skin. These cells synthesize melanin pigment that protects the genome from harmful ultraviolet radiations. Perturbations in melanocyte functioning lead to pigmentary disorders such as piebaldism, albinism, vitiligo, melasma, and melanoma. Zebrafish is an excellent model system to understand melanocyte functions. The presence of conspicuous pigmented melanocytes, ease of genetic manipulation, and availability of transgenic fluorescent lines facilitate the study of pigmentation. This study employs the use of wild-type and transgenic zebrafish lines that drive green fluorescent protein (GFP) expression under mitfa and tyrp1 promoters that mark various stages of melanocytes. Morpholino-based silencing of candidate genes is achieved to evaluate the phenotypic outcome on larval pigmentation and is applicable to screen for regulators of pigmentation. This protocol demonstrates the method from microinjection to imaging and fluorescence-activated cell sorting (FACS)-based dissection of phenotypes using two candidate genes, carbonic anhydrase 14 (Ca14) and a histone variant (H2afv), to comprehensively assess the pigmentation outcome. Further, this protocol demonstrates segregating candidate genes into melanocyte specifiers and differentiators that selectively alter melanocyte numbers and melanin content per cell, respectively.
Topics: Animals; Melanocytes; Pigmentation; Pigmentation Disorders; Reverse Genetics; Zebrafish
PubMed: 35312674
DOI: 10.3791/62955