Mechanism Of Color Formation Research Articles

In situ synthesis of cobalt silicide particle reinforcing and coloring Si3N4 ceramics

AbstractIn this paper, silicon nitride (Si3N4) ceramics with black color and high toughness were fabricated by gas pressure sintering and characterized by X‐ray diffraction, Raman, scanning electron microscopy, EDS, and transmission electron microscopy. The in situ formed cobalt silicide was confirmed to contribute to the black color through the introduction of CoO. Due to the addition of CoO, the growth of β‐Si3N4 grains is promoted, forming elongated grains, and eventually forms the self‐reinforcing microstructure. However, with adding excessive CoO, interfacial debonding is found between cobalt silicide and Si3N4 matrix and a decrease in strength was resulted. The optimum composition is 1 mol% CoO in Si3N4, with the fracture toughness of 9.9 ± 0.3 MPa m1/2, flexural strength of 826.1 ± 46.0 MPa, and a much darker black color. The mechanism of color formation is discussed where the black color derives mainly from the metallic silicon and additionally the porosity.

Transcriptomics Integrated With Widely Targeted Metabolomics Reveals the Mechanism Underlying Grain Color Formation in Wheat at the Grain-Filling Stage.

Colored wheat grains have a unique nutritional value. To elucidate the color formation mechanism in wheat seeds, comprehensive metabolomic and transcriptomic analyses were conducted on purple (Dianmai 20-1), blue (Dianmai 20-8), and white (Dianmai 16) wheat at the grain-filling stage. The results showed that the flavonoid biosynthesis pathway was closely related to grain color formation. Among the 603 metabolites identified in all varieties, there were 98 flavonoids. Forty-six flavonoids were detected in purple and blue wheat, and there were fewer flavonoids in white wheat than in colored wheat. Integrated transcriptomic and metabolomic analyses showed that gene expression modulated the flavonoid composition and content, resulting in different metabolite levels of pelargonidin, cyanidin, and delphinidin, thus affecting the color formation of wheat grains. The present study clarifies the mechanism by which pigmentation develops in wheat grains and provides an empirical reference for colored wheat breeding.

Isolation and identification of pigments from oyster mushrooms with black, yellow and pink caps

The genus Pleurotus, namely oyster mushroom, is widely cultivated and consumed worldwide. Cap color is an important commercial trait for oyster mushroom. Diverse color is determined by various pigment constituents. However, the pigments of oyster mushrooms are still ambiguous. In this study, we extracted and identified pigments of oyster mushroom species with black, yellow and pink cap color. The extracted pigments appearing the three color types correspondingly to the cap color, which were all identified as melanin using a panel of spectroscopic and physical/imaging techniques. Nevertheless, HPLC and elemental analysis indicated that the melanin in oyster mushrooms was actually a mixture of eumelanin and phaeomelanin. Differences in the quantities and relative proportions of eumelanin and phaeomelanin resulted in the color variation in oyster mushroom caps. Electron microscopy studies showed that the melanin units are likely located in the cell wall, as reported in other fungi. The pigments in oyster mushrooms with three different cap color were extracted and identified for the first time in this study, which provided fundamental knowledge for future studies on the mechanism of color formation in mushrooms.

Biomimetic approaches to color formation in ecological architecture

The article discusses the characteristics and features of the color formation in nature for solving problems of ecological architecture. The analysis of the main directions of research on the significance and possibilities of color solutions in creating an ecologically sustainable urban environment is presented. It is proposed to use analogs of nature to obtain natural features and qualities of ecological design of buildings, including in the formation of the color structural component of the design. As a result of the analysis of the studies, the mechanisms of color formation in nature, based on functional expediency, adaptation to the conditions of life in the environment, have been identified. The mechanism of formation of pigment, structural and combined colors in nature is considered. On the basis of the presented analysis of the functionality of color formation in nature, coloristic means of regulating the energy-efficient and environmental parameters of the building, namely thermoregulation, regulation of illumination, humidity, are identified. The examples of color solutions of building finishing aimed at adaptation to external environmental conditions are analyzed. The methods and possibilities of forming the color structure on the basis of the studied natural analogues for solving the problems of modern ecological architecture are systematized.

A highly mutable GST is essential for bract colouration in Euphorbia pulcherrima Willd. Ex Klotsch

BackgroundMutation breeding is an extraordinary tool in plant breeding to increase the genetic variability, where mutations in anthocyanin biosynthesis are targets to generate distinctive phenotypes in ornamental species. In poinsettia, ionizing radiation is routinely applied in breeding programs to obtaining a range of colours, with nearly all pink and white varieties being obtained after γ- or X-ray mutagenesis of red varieties. In the present study we performed a thorough characterization of a potential mutagenesis target gene as the main responsible for the ‘white paradox’ in poinsettia.ResultsWe identified a GST gene in poinsettia (Bract1) as an essential factor for the expression of anthocyanin-based red colouration of bracts, which presents a high phylogenetic similarity to known anthocyanin-related GSTs. Red poinsettia varieties and white mutants generated from these varieties by X-ray were analysed for polymorphisms related to the ‘white paradox’ in the species. A 4 bp mutation in a short repeat within the coding region of Bract1 is most likely responsible for the appearance of white phenotypes upon irradiation treatment. The polymorphism between wild-type and mutant alleles co-segregates with the phenotype in progeny from heterozygous red and white parents. Moreover, overexpression of Bract1 wild-type allele in Arabidopsis tt19 mutants restored the anthocyanin phenotype, while the Bract1 mutated allele showed to be non-functional.ConclusionsThe identified repeat seems to be highly unstable, since mutated plants can be easily detected among fewer than 200 shoots derived from 10 mutated plants. Our data indicate that particular short repeat sequences, similar to microsatellite sequences or so-called dynamic mutations, might be hot spots for genetic variability. Moreover, the identification of the Bract1 mutation fills a gap on the understanding on the molecular mechanism of colour formation in poinsettia.

Identification of blood-red color formation in edible bird’s nests provides a new strategy for safety control

In order to reveal the color formation mechanism of blood-red edible bird’s nests (EBNs) and develop a quick and specific strategy to distinguish the artificial fake one, multiple methods of UPLC-TOF/MS, UV, NMR, FT-IR and 2D IR were used to detect the chemical markers of the reddening reaction, the results showed that the reddening substances were C9H10N2O5 and C9H9NO6, which were verified as products of a phenol-keto tautomerism evolved from l-tyrosine. Moreover, natural and artificial red EBNs with varying degrees of chemical fumigation also can be successfully distinguished using the chemical markers, and the protein variation in SDS-PAGE gel could also support the distinction. This work established a systematic method of chemical identification for both natural and artificial blood-red EBNs, and provided a new identification strategy for food safety control that can promote the development of a healthier market of EBNs.

Exploring the Molecular Mechanism of Blue Flower Color Formation in Hydrangea macrophylla cv. "Forever Summer".

Hydrangea macrophylla has a large inflorescence and rich colors, which has made it one of the most popular ornamental flowers worldwide. Thus far, the molecular mechanism of flower color formation in H. macrophylla flowers is unknown. By comparing the pigment content and transcriptome data of the bud period (FSF1), discoloration period (FSF2) and full-bloom stage (FSF3) of infertile blue flowers of H. macrophylla cv. “Forever Summer,” we found that genes associated with anthocyanin production were most associated with the formation of blue infertile flowers throughout development. The anthocyanin biosynthesis pathway is the main metabolic pathway associated with flower color formation, and the carotenoid biosynthesis pathway appeared to have almost no contribution to flower color. There was no competition between the flavonoid and flavonol and anthocyanin biosynthesis pathways for their substrate. At FSF1, the key genes CHS and CHI in the flavonoid biosynthesis pathway were up-regulated, underlying the accumulation of a substrate for anthocyanin synthesis. By FSF3, the downstream genes F3H, C3′5′H, CYP75B1, DFR, and ANS in the anthocyanin biosynthesis pathway were almost all up-regulated, likely promoting the synthesis and accumulation of anthocyanins and inducing the color change of infertile flowers. By analyzing protein–protein interaction networks and co-expression of transcription factors as well as differentially expressed structural genes related to anthocyanin synthesis, we identified negatively regulated transcription factors such as WER-like, MYB114, and WDR68. Their site of action may be the key gene DFR in the anthocyanin biosynthesis pathway. The potential regulatory mechanism of flower color formation may be that WER-like, MYB114, and WDR68 inhibit or promote the synthesis of anthocyanins by negatively regulating the expression of DFR. These results provide an important basis for studying the infertile flower color formation mechanism in H. macrophylla and the development of new cultivars with other colors.

Effect of chemical composition of black tea infusion on the color of milky tea

Milky tea is popular in many countries and its color is an important sensory property. The effects of black tea infusion on the color of milky tea prepared with non-dairy creamer were investigated. The results showed that the redder black tea infusion produced milky tea with more redness, and the color of milky tea was a pleasant pink when the a* value (redness indicator) was in the range of 6.0–7.0. Correlation analysis revealed that the respective theaflavins (TFs), thearubigins (TRs), thearubigins (TBs), (–)-epigallocatechin-3-gallate (EGCG) and chlorogenic acid contents significantly correlated with the a* values of milky tea. A series of complementary experiments were performed to elucidate that TFs and EGCG contributed to the redness of milky tea. The color formation was mainly associated with the binding of phenols to the proteins in the non-dairy creamer. These results contribute to understand the mechanism of color formation in milky tea.

ANALYSIS OF EXAMPLES OF THE APPLICATION OF THE BIOCLIMATIC APPROACH TO COLOR SOLUTIONS IN HIGH-RISE BUILDINGS

The challenge in the design of bioclimatic high-rise buildings is to return to a design that is compatible with the environment, climate. The purpose of the article is to analyze the means of color formation in living and inanimate nature, which can be used in color solutions for the facades of bioclimatic high-rise buildings to ensure their durability, regulate energy efficient and environmental parameters (thermoregulation, illumination, humidity).
 The need to analyze and research the bioclimatic trend in the design of modern high-rise buildings is based on the emergence of a significant number of implemented innovative design solutions. Such projects differ from each other in architectural styles, directions and means of implementing the bioclimatic approach, placement and interaction with the environment.
 The application of various natural mechanisms of color formation in nature is analyzed from the point of view of ensuring functional use in facade solutions of modern high-rise buildings. The main advantages of the pigment and structural mechanism of color formation to ensure thermal insulation of the building, durability of facade finishing while maintaining the quality of color solutions are determined.
 The results of the study made it possible to establish that today the use of the bioclimatic approach to the use of color in the facades of high-rise buildings determines new trends in the creation of eco-facades, based on the use of natural analogues and associated with the introduction of the latest design and technological solutions.

Combined Analysis of Transcriptome and Metabolome Reveals the Potential Mechanism of Coloration and Fruit Quality in Yellow and Purple Passiflora edulis Sims.

Passion fruit (Passiflora edulis Sims) can be divided into yellow and purple varieties. However, information about coloration and fruit quality between the two varieties is limited. To reveal the underlying mechanism of color formation in this fruit, a combined analysis of the metabolome and transcriptome was conducted in this study. The results showed that most of the evaluated flavonols, anthocyanins, and flavanols were significantly upregulated in purple fruit compared to their levels in yellow fruit. Flavonoid and flavonoid carbonoside accumulation was markedly higher in yellow fruit than in purple fruit. The accumulation of organic acids, phenolic acids, lipids, sugars, and lignans was significantly different in the yellow and purple varieties. These results were consistent with the results from the RNA-Seq profile. This study will enable us to identify genes for targeted genetic engineering to improve the nutritional and market value of passion fruit. In addition, the peel and pulp of passion fruit contained certain health-promoting compounds, highlighting the potential application of passion fruit as a functional food and providing direction for future breeding programs and production.

RETRACTED ARTICLE: Contribution of anthocyanin pathways to fruit flesh coloration in pitayas

BackgroundColor formation in Hylocereus spp. (pitayas) has been ascribed to the accumulation of betalains. However, several studies have reported the presence of anthocyanins in pitaya fruit and their potential role in color formation has not yet been explored. In this study, we profiled metabolome and transcriptome in fruit of three cultivars with contrasting flesh colors (red, pink and white) to investigate their nutritional quality and the mechanism of color formation involving anthocyanins.ResultsResults revealed that pitaya fruit is enriched in amino acid, lipid, carbohydrate, polyphenols, vitamin and other bioactive components with significant variation among the three cultivars. Anthocyanins were detected in the fruit flesh and accumulation levels of Cyanidin 3-glucoside, Cyanidin 3-rutinoside, Delphinidin 3-O-(6-O-malonyl)-beta-glucoside-3-O-beta-glucoside and Delphinidin 3-O-beta-D-glucoside 5-O-(6-coumaroyl-beta-D-glucoside) positively correlated with the reddish coloration. Transcriptome data showed that the white cultivar tends to repress the anthocyanin biosynthetic pathway and divert substrates to other competing pathways. This perfectly contrasted with observations in the red cultivar. The pink cultivar however seems to keep a balance between the anthocyanin biosynthetic pathway and the competing pathways. We identified several active transcription factors of the MYB and bHLH families which can be further investigated as potential regulators of the anthocyanin biosynthetic genes.ConclusionsCollectively, our results suggest that anthocyanins partly contribute to color formation in pitaya fruit. Future studies aiming at manipulating the biosynthetic pathways of anthocyanins and betalains will better clarify the exact contribution of each pathway in color formation in pitayas. This will facilitate efforts to improve pitaya fruit quality and appeal.

Forecasting structure of natural products through color formation process by thin layer chromatography

With booming of computer technology, it is feasible to quantitatively extract valuable information from readily available image of objects, which dramatically reduces the cost and improves the efficiency. In this work, a structural classification method, based on data extracted from color formation process on thin layer chromatography (TLC) plates through computer processing, was established for natural products. Representative natural products exhibited good clustering and separation according to the extracted color feature, and structure of natural products can be classified by the distribution region in the color system. This method provides structural information for typical types of natural products directly from the formed color on TLC, which is very efficient and make portable device-based structure analysis of natural products possible. In addition, a general mechanism of color formation was proposed. This method is free from special instrument, high-throughput, and would facilitate large-scale screening of bioactives from natural sources.

The Color Formation Mechanism of the Blue Karst Lakes in Jiuzhaigou Nature Reserve, Sichuan, China

The karst lakes in Jiuzhaigou Nature Reserve are an integral part of the karst lake landscape, yet research on the formation mechanism for the color of the blue-green lakes in Jiuzhaigou is insufficient. With the help of hyperspectral instruments, coupled with hydro-chemical analysis, this paper elaborates on the unique color characteristics of the Jiuzhaigou karst lakes, delves into the color formation mechanism of the lakes, establishes a regression equation for the color of the lakes as well as the water quality parameters, and sheds light upon the causes for the color distinction between the karst lakes in Jiuzhaigou and the plateau freshwater lakes. The experiment shows that the Jiuzhaigou karst lakes are primarily blue and green, while the proportion of short-wavelength light in the normalized water-leaving radiance and the total incident irradiance of lake water is higher. Based on the redundancy analysis and the correlation analysis, travertine deposition is the core link in the color formation of the blue karst lakes in Jiuzhaigou, while the selective reflection and scattering of the suspended calcium carbonate particulate matters towards visible light represents the optical foundation for the formation. In addition, physical factors such as depth and transparency, changes to the water quality parameters that affect the travertine deposition rate, and the eutrophication process will all exert significant influence over the formation. By building on water-leaving radiance, this paper quantifies the lake color with the tristimulus values (R, G, B) via colorimetrical methods, which features solid goodness of fit with the linear regression equation established based on the water quality parameters. The principal component analysis and colorimetrical analysis show that the color of the karst lakes in Jiuzhaigou varies substantially from that of the plateau freshwater lakes, which mainly results from the difference in the water quality. Research conducted in this paper on the color formation mechanism of the distinct blue karst lakes in Jiuzhaigou illuminates the formation and maintenance mechanism of the plateau karst lakes, which is conducive to better understanding towards the relationship between the water quality and colors of the karst lakes, and provides scientific proof for the establishment of the water quality assessment indicator system based on the colors of the karst lakes.

A spectrophotometric method for estimation of titanium alkoxide, a catalytically active form of titanium in oligomer/ polymers

A spectrophotometric method was developed for the selective estimation of titanium in alkoxide form in the presence of TiO2. Polymers like polybutylene terephthalate have been synthesized by using homogeneous catalyst such as titanium tetra-isopropoxide (TTIP). These types of catalysts are susceptible to moisture and convert to inactive TiO2. Hence, it is essential to have analytical method for selective estimation of alkoxide form of titanium. In this study, we have used O-cresol to convert TTIP to tetra O- cresyl titanate, a colored compound, which was quantitatively analyzed by spectrophotometric technique. Polymer matrix was used in standard solution to compensate the effect of matrix during UV-VIS measurements. Method validation was successfully carried out for linearity, reproducibility, recovery, specificity and the observed acceptable results as per ICH guidelines. 2-sample t-test was performed to check the variation observed between two analysts and the observed p-value indicated the results were statistically similar to each other. Mechanism of color formation was established by synthesis of colored complex called tetra O-cresyl titanate. The structure was supported by ICP, CHNS and NMR analysis. The method is simple and easy to implement at manufacturing plant for initial monitoring of active catalyst concentration in polymer/oligomer samples.

Transcriptomic investigation of the basis of Corona and petal colour in Chinese narcissus

ABSTRACT Chinese narcissus is a traditional flower with gorgeous corona and petal colour. The carotenoid biosynthesis pathway is primarily responsible for colour formation in narcissus flower. However, the role of carotenoid biosynthesis enzymes and intermediates in colour development, and the molecular basis of differences between orange-yellow corona and milky-white petals are unclear. Here, we performed RNA-Seq using Illumina HiSeq platform and de novo transcriptome assembly to predict the functions of the identified significantly differentially expressed genes (DEGs). We investigated genes expression in narcissus corona and petal tissues on the first and seventh day of flowering. 14 colour -related genes were further analysed by qRT-PCR. The significantly DEGs encoded various kinds of enzymes and transcription factors (TFs) associated with carotenoid and flavonoid biosynthesis pathways, respectively. These DEGs mainly included phytoene synthase ( PSY ) gene, lycopene epsilon cyclase ( LCYE ) gene, β-carotene hydroxylase ( BCH ) gene, β-carotene isomerase gene and AP2/ ERF, B3, MYB, NAC and WRKY TFs. Additionally, an in-depth analysis of chlorophyll biosynthesis and degradation pathways was performed. These results enhance our understanding of the mechanism of colour formation in narcissus flower and provide a basis for further investigation of the functions of proteins encoded by the annotated unigenes and cDNA sequences of narcissus.

Hybrid de novo transcriptome assembly of poinsettia (Euphorbia pulcherrima Willd. Ex Klotsch) bracts

BackgroundPoinsettia is a popular and important ornamental crop, mostly during the Christmas season. Its bract coloration ranges from pink/red to creamy/white shades. Despite its ornamental value, there is a lack of knowledge about the genetics and molecular biology of poinsettia, especially on the mechanisms of color formation. We performed an RNA-Seq analysis in order to shed light on the transcriptome of poinsettia bracts. Moreover, we analyzed the transcriptome differences of red- and white-bracted poinsettia varieties during bract development and coloration. For the assembly of a bract transcriptome, two paired-end cDNA libraries from a red and white poinsettia pair were sequenced with the Illumina technology, and one library from a red-bracted variety was used for PacBio sequencing. Both short and long reads were assembled using a hybrid de novo strategy. Samples of red- and white-bracted poinsettias were sequenced and comparatively analyzed in three color developmental stages in order to understand the mechanisms of color formation and accumulation in the species.ResultsThe final transcriptome contains 288,524 contigs, with 33% showing confident protein annotation against the TAIR10 database. The BUSCO pipeline, which is based on near-universal orthologous gene groups, was applied to assess the transcriptome completeness. From a total of 1440 BUSCO groups searched, 77% were categorized as complete (41% as single-copy and 36% as duplicated), 10% as fragmented and 13% as missing BUSCOs. The gene expression comparison between red and white varieties of poinsettia showed a differential regulation of the flavonoid biosynthesis pathway only at particular stages of bract development. An initial impairment of the flavonoid pathway early in the color accumulation process for the white poinsettia variety was observed, but these differences were no longer present in the subsequent stages of bract development. Nonetheless, GSTF11 and UGT79B10 showed a lower expression in the last stage of bract development for the white variety and, therefore, are potential candidates for further studies on poinsettia coloration.ConclusionsIn summary, this transcriptome analysis provides a valuable foundation for further studies on poinsettia, such as plant breeding and genetics, and highlights crucial information on the molecular mechanism of color formation.

Transcriptome and metabolome profiling unveil the mechanisms of Ziziphus jujuba Mill. peel coloration

Coloring is an important external quality of jujube fruit (Ziziphus jujuba Mill.), however during long-term storage, its commercial value degrades as the peel color and lustre significantly fade. Here, the gene expression and metabolite concentration were profiled in the fruit peel of jujube harvested at three ripening periods to elucidate the color formation mechanism. A strong accumulation of malvidin 3-O-glucoside and delphinidin 3-O-glucoside correlated with the reddening of jujube peel. At the onset of the fruit ripening, strong activities of the genes in the early steps of the flavonoid biosynthetic pathway were observed. During the last ripening periods, three UDP-glucose flavonoid 3-O-glucosyltransferase (UFGT) involved in the accumulation of anthocyanins were significantly increased and their proper manipulation could delay the peel reddening. This study sheds light on the metabolic pathways and candidate genes underlying the peel coloration in jujube and lays a foundation for the improvement of jujube fruit appeal during long-term storage.

Integrative analysis of metabolome and transcriptome reveals the mechanism of color formation in pepper fruit (Capsicum annuum L.)

To understand the mechanism of the color formation of pepper fruit, integrative analysis of the metabolome and transcriptome profiles was performed in pepper varieties with 4 different fruit colors. A total of 188 flavonoids were identified, and most of the anthocyanins, flavonols and flavones showed markedly higher abundances in purple variety than in other varieties, which was linked to the high expression of flavonoid synthesis and regulatory genes. Using weighted gene co-expression network analyses, modules related to flavonoid synthesis and candidate genes that regulate flavonoid synthesis and transport were identified. Furthermore, the analysis of 12 carotenoids showed that the content of xanthophylls at 50 days after anthesis was significantly different between the four pepper varieties, which was resulted from the differential expressions of genes downstream of the carotenoid pathway. Our results provide new insights into the understanding of the synthesis and accumulation of flavonoids and carotenoids in pepper fruit.

Combined effects of nanosecond laser-induced surface oxidation and nanostructure formation for selective colorization of nickel surfaces

Metal surfaces can be nanostructured by laser irradiation making use of different effects ranging from thin film generation to nanostructures formation. Here, the colorization of pure nickel surfaces by nanosecond laser irradiation in air is demonstrated and studied in detail. Correlations between chromaticity coordinates and laser-processing parameter show that the accumulated fluence is the dominating factor in creation of a specific colored surface. The color of the laser-irradiated surfaces shows both angle-dependent and angle-independent in reliance on the processing conditions. The examination of the laser-colored surface demonstrates that lateral and vertical organized, laser-induced structures with nano-, micro-, and mesoscopic scales can be found simultaneously which contribute to the colorization in a particular manner. A comprehensive analysis of the processes involved in the color formation at nickel was performed by examining the surfaces by SEM, reflectometry, XPS, and XRD to verify the multi-process mechanisms of color formation. The most saturated colors result from interference effects within the redeposited layers. It was found that controlling the hatching distance applying optimized laser fluence enables a wider color range and allows a very precise setting of the color. Based on the extracted laser-processing parameters, the surface coloration of arbitrary pattern with desired optical properties becomes practicable, and nanosecond laser color marking can, therefore, be expanded to potentially new applications.

Mechanisms of color formation in drug substance and mitigation strategies for the manufacture and storage of therapeutic proteins produced using mammalian cell culture

Abstract Drug substance (DS) appearance is an important quality attribute that is tested before product release. Color variation in DS batches or color change during storage can be indicative of the presence of contaminants, impurities or degradation products and may be linked to the manufacturing process, DS formulation or the stability of the therapeutic proteins. Atypical DS color other than colorless or pale yellow has been recently observed and may result in rejected manufacturing batches and financial loss due to concerns on product quality and visually matching placebo in clinical trials. This review focuses on the origins of atypical color and changes in DS during manufacturing processes using mammalian cell culture and storage. The purposes here are to understand the link between changes in the DS color and various process parameters and to provide necessary information to our readers regarding product quality control strategies with respect to DS color.