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Photochemistry and Photobiology Jan 2021Optical properties of plant leaves are relevant to evaluate their physiological state and stress effect. The main objective of this work was to study how variegation,...
Optical properties of plant leaves are relevant to evaluate their physiological state and stress effect. The main objective of this work was to study how variegation, pigment composition or reflective features modifies leaves' photophysical behavior. For this purpose, green leaves (Ficus benjamina), purple leaves (Tradescantia pallida), green leaves covered by white trichomes (Cineraria maritima) and variegated leaves (Codiaeum aucubifolium) were analyzed. Firstly, foliar surface morphology was evaluated by scanning electron microscopy. UV-vis and near-IR reflectance and transmittance spectra were obtained to calculate absorption (k) and scattering (s) coefficients. The theoretical approaches of Pile of Plates and Kubelka-Munk's theory resulted still valid for nonstandard leaves with differing surface conditions. However, frequently used spectral indices were not reliable for predicting water content, when leaves differed from conventional ones. The proportionality between the absorption factor and chromophore/pigment concentration was also lost for hairy leaves. A simplified model to describe these facts was presented here. Fluorescence spectra were recorded and corrected, due to light re-absorption. Water-optical parameter connection and pigment-optical parameter connection were thoroughly discussed. Leaf surface morphology and pigmentation have not only influenced the optical features of leaves but also played a role in the effect that particulate matter could cause on leaf photosynthesis.
Topics: Fluorescence; Light; Particulate Matter; Pigmentation; Plant Leaves; Plants; Species Specificity; Surface Properties
PubMed: 32297341
DOI: 10.1111/php.13273 -
Journal of Molecular Biology Nov 2019Phenotypic heterogeneity in bacterial cell populations allows genetically identical organisms to different behavior under similar environmental conditions. The... (Review)
Review
Phenotypic heterogeneity in bacterial cell populations allows genetically identical organisms to different behavior under similar environmental conditions. The Gram-negative bacterium Photorhabdus luminescens is an excellent organism to study phenotypic heterogeneity since their life cycle involves a symbiotic interaction with soil nematodes as well as a pathogenic association with insect larvae. Phenotypic heterogeneity is highly distinct in P. luminescens. The bacteria exist in two phenotypic forms that differ in various morphologic and phenotypic traits and are therefore distinguished as primary (1°) and secondary (2°) cells. The 1 cells are bioluminescent, pigmented, produce several secondary metabolites and exo-enzymes, and support nematode growth and development. The 2° cells lack all these 1°-specific phenotypes. The entomopathogenic nematodes carry 1° cells in their upper gut and release them into an insect's body after slipping inside. During insect infection, up to the half number of 1° cells undergo phenotypic switching and convert to 2° cells. Since the 2° cells are not able to live in nematode symbiosis any more, they cannot re-associate with their symbiosis partners after the infection and remain in the soil. Phenotypic switching in P. luminescens has to be tightly regulated since a high switching frequency would lead to a complete break-down of the nematode-bacteria life cycle. Here, we present the main regulatory mechanisms known to-date that are important for phenotypic switching in P. luminescens cell populations and discuss the biological reason as well as the fate of the 2° cells in the soil.
Topics: Bacterial Physiological Phenomena; Bacterial Proteins; Biological Variation, Population; Gene Expression Regulation, Bacterial; Life Cycle Stages; Phenotype; Photorhabdus; Pigmentation; Quorum Sensing; Symbiosis
PubMed: 31022406
DOI: 10.1016/j.jmb.2019.04.015 -
Nature Reviews. Genetics Aug 2020Coloration is an easily quantifiable visual trait that has proven to be a highly tractable system for genetic analysis and for studying adaptive evolution. The... (Review)
Review
Coloration is an easily quantifiable visual trait that has proven to be a highly tractable system for genetic analysis and for studying adaptive evolution. The application of genomic approaches to evolutionary studies of coloration is providing new insight into the genetic architectures underlying colour traits, including the importance of large-effect mutations and supergenes, the role of development in shaping genetic variation and the origins of adaptive variation, which often involves adaptive introgression. Improved knowledge of the genetic basis of traits can facilitate field studies of natural selection and sexual selection, making it possible for strong selection and its influence on the genome to be demonstrated in wild populations.
Topics: Adaptation, Biological; Animals; Biological Evolution; Genetic Variation; Genome; Genomics; Multifactorial Inheritance; Mutation; Phenotype; Pigmentation; Pigments, Biological; Quantitative Trait Loci; Quantitative Trait, Heritable; Selection, Genetic
PubMed: 32382123
DOI: 10.1038/s41576-020-0234-z -
Indian Journal of Medical Microbiology Jan 2021Many pathogenic organisms do produce different types of the pigments, helpful in the presumptive laboratory diagnosis of the microorganisms. These pigments are...
Many pathogenic organisms do produce different types of the pigments, helpful in the presumptive laboratory diagnosis of the microorganisms. These pigments are malevolent as well as benevolent to the mankind. Most of the time, the pigmented organisms do display resistance to the many classes of the drugs in vitro and in vivo. Most of Acinetobacter sp are nonpigmented. Few strains produce diffusible brown pigment and rarely produce black and indigo coloured pigments (Liu1 and Nizet, 2009; Nosanchuk and Casadevall, 2003; Moazamian et al., 2018; Saviola, 2018; Saviola, 2014; Kirti et al., 2014; German et al., 2018; Coelho-Souza et al., 2014) [1-8]. This is the first Indian human case report is of "The Viridescent Acinetobacter lwoffii" (dark green pigmented) isolated from the central line blood culture which was susceptible to the many classes of the drugs in vitro and correlated well with in vivo compliance.
Topics: Acinetobacter; Acinetobacter Infections; Humans; India; Pigmentation
PubMed: 33610246
DOI: 10.1016/j.ijmmb.2020.09.001 -
Developmental Dynamics : An Official... Nov 2017Black pigment cells, melanocytes, arise early during development from multipotent neural crest cells. Melanocytes protect human skin from DNA damaging sunrays and... (Review)
Review
Black pigment cells, melanocytes, arise early during development from multipotent neural crest cells. Melanocytes protect human skin from DNA damaging sunrays and provide color for hair, eyes, and skin. Several disorders and diseases originate from these cells, including the deadliest skin cell cancer, melanoma. Thus, melanocytes are critical for a healthy life and for protecting humans from disease. Due to the ease of visualizing pigment cells through transparent larvae skin and conserved roles for zebrafish melanophore genes to mammalian melanocyte genes, zebrafish larvae offer a biologically relevant model for understanding pigment cell development and disease in humans. This review discusses our current knowledge of melanophore biology and how zebrafish are contributing to improving how diseases of melanocytes are understood and treated in humans. Developmental Dynamics 246:889-896, 2017. © 2017 Wiley Periodicals, Inc.
Topics: Animals; Humans; Melanocytes; Melanoma; Melanophores; Pigmentation; Zebrafish
PubMed: 28710811
DOI: 10.1002/dvdy.24550 -
The Journal of Experimental Biology May 2022Animals benefit from phenotypic plasticity in changing environments, but this can come at a cost. Colour change, used for camouflage, communication, thermoregulation and... (Review)
Review
Animals benefit from phenotypic plasticity in changing environments, but this can come at a cost. Colour change, used for camouflage, communication, thermoregulation and UV protection, represents one of the most common plastic traits in nature and is categorised as morphological or physiological depending on the mechanism and speed of the change. Colour change has been assumed to carry physiological costs, but current knowledge has not advanced beyond this basic assumption. The costs of changing colour will shape the evolution of colour change in animals, yet no coherent research has been conducted in this area, leaving a gap in our understanding. Therefore, in this Review, we examine the direct and indirect evidence of the physiological cost of colour change from the cellular to the population level, in animals that utilise chromatophores in colour change. Our Review concludes that the physiological costs result from either one or a combination of the processes of (i) production, (ii) translocation and (iii) maintenance of pigments within the colour-containing cells (chromatophores). In addition, both types of colour change (morphological and physiological) pose costs as they require energy for hormone production and neural signalling. Moreover, our Review upholds the hypothesis that, if repetitively used, rapid colour change (i.e. seconds-minutes) is more costly than slow colour change (days-weeks) given that rapidly colour-changing animals show mitigations, such as avoiding colour change when possible. We discuss the potential implications of this cost on colour change, behaviour and evolution of colour-changing animals, generating testable hypotheses and emphasising the need for future work to address this gap.
Topics: Adaptation, Physiological; Animals; Chromatophores; Color; Phenotype; Pigmentation
PubMed: 35593398
DOI: 10.1242/jeb.210401 -
Angewandte Chemie (International Ed. in... Jul 2020Alkaptonuria (AKU) is a rare disease characterized by high levels of homogentisic acid (HGA); patients suffer from tissue ochronosis: dark brown pigmentation, especially...
Alkaptonuria (AKU) is a rare disease characterized by high levels of homogentisic acid (HGA); patients suffer from tissue ochronosis: dark brown pigmentation, especially of joint cartilage, leading to severe early osteoarthropathy. No molecular mechanism links elevated HGA to ochronosis; the pigment's chemical identity is still not known, nor how it induces joint cartilage degradation. Here we give key insight on HGA-derived pigment composition and collagen disruption in AKU cartilage. Synthetic pigment and pigmented human cartilage tissue both showed hydroquinone-resembling NMR signals. EPR spectroscopy showed that the synthetic pigment contains radicals. Moreover, we observed intrastrand disruption of collagen triple helix in pigmented AKU human cartilage, and in cartilage from patients with osteoarthritis. We propose that collagen degradation can occur via transient glycyl radicals, the formation of which is enhanced in AKU due to the redox environment generated by pigmentation.
Topics: Alkaptonuria; Cartilage, Articular; Electron Spin Resonance Spectroscopy; Homogentisic Acid; Humans; Magnetic Resonance Spectroscopy; Osteoarthritis; Oxidation-Reduction; Pigmentation; Pigments, Biological
PubMed: 32219972
DOI: 10.1002/anie.202000618 -
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 -
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 -
Proceedings. Biological Sciences Aug 2022Organisms living on the seafloor are subject to encrustations by a wide variety of animals, plants and microbes. Sea urchins, however, thwart this covering. Despite...
Organisms living on the seafloor are subject to encrustations by a wide variety of animals, plants and microbes. Sea urchins, however, thwart this covering. Despite having a sophisticated immune system, there is no clear molecular mechanism that allows sea urchins to remain free of epibiotic microorganisms. Here, we test the hypothesis that pigmentation biosynthesis in sea urchin spines influences their interactions with microbes using CRISPR/Cas9. We report three primary findings. First, the microbiome of sea urchin spines is species-specific and much of this community is lost in captivity. Second, different colour morphs associate with bacterial communities that are similar in taxonomic composition, diversity and evenness. Lastly, loss of the pigmentation biosynthesis genes polyketide synthase and flavin-dependent monooxygenase induces a shift in which bacterial taxa colonize sea urchin spines. Therefore, our results are consistent with the hypothesis that host pigmentation biosynthesis can, but may not always, influence the microbiome in sea urchin spines.
Topics: Animals; Bacteria; Microbiota; Pigmentation; Polyketide Synthases; Sea Urchins
PubMed: 35975446
DOI: 10.1098/rspb.2022.1088