Rapid Color Research Articles

UV-induced feather color change reflects its porphyrin content.

Pigmentary coloration is widespread in animals. Its evolutionary and ecological features are often attributed to the property of predominant pigments; therefore, most research has focused on predominant pigments such as carotenoids in carotenoid-based coloration. However, coloration results from predominant pigments and many other minority pigments, and the importance of the latter is overlooked. Here, we focused on porphyrin, an "uncommon" pigment found in bird feathers, and investigated its importance in the context of feather color changes in the barn swallow Hirundo rustica. We found that the "pheomelanin-based coloration" of the barn swallow faded after the irradiation of UV light, and this effect was particularly strong in the feathers of young swallows (nestlings and fledglings, here). We also found that it is not the predominant pigment, pheomelanin, but protoporphyrin IX pigment that showed the same pattern of depigmentation after the irradiation of UV light, particularly in the feathers of young swallows. In fact, the abovementioned age-dependent feather color change was statistically explained by the amount of porphyrin in the feathers. The current study demonstrates that a minority pigment, porphyrin, explains within-season dynamic color change, an ecological feature of feather coloration. The porphyrin-mediated rapid color change would benefit young birds, in which feather coloration affects the parental food allocation during a few weeks before independence, but not later. Future studies should not ignore these minor but essential pigments and their evolutionary and ecological functions.

A fish can change its stripes: investigating the role of body colour and pattern in the bluelined goatfish.

Bluelined goatfish (Upeneichthys lineatus) rapidly change their body colour from a white horizontally banded pattern to a seemingly more conspicuous vertically banded red pattern, often when foraging. Given the apparent conspicuousness of the pattern to a range of observers, it seems unlikely that this colour change is used for camouflage and instead may be used for communication/signalling. Goatfish often drive multispecies associations, and it is possible that goatfish use this colour change as a foraging success signal to facilitate cooperation, increase food acquisition, and reduce predation risk through a 'safety in numbers' strategy. Using a novel approach, we deployed 3D model goatfish in different colour morphs-white without bands, white with black vertical bands, and white with red vertical bands-to determine whether the red colouration is an important component of the signal or if it is only the vertical banding pattern, regardless of colour, that fish respond to as an indicator of foraging success. Use of remote underwater video allowed us to obtain information without the influence of human observers on the communities and behaviours of other fish in response to these different colours exhibited by goatfish. We found that conspecifics were more abundant around the black- and red-banded model fish when compared with the white models. Conspecifics were also more likely to forage around the models than to pass or show attraction, but this was unaffected by model colour. No difference in the abundance and behaviour of associated heterospecifics around the different models was observed, perhaps due to the static nature of the models. Some species did, however, spend more time around the red- and black-banded fish, which suggests the change in colour may indicate benefits in addition to food resources. Overall, the results suggest that the body colour/pattern of U. lineatus is likely a signalling tool but further work is required to explore the benefits to both conspecifics and heterospecifics and to further determine the behavioural functions of rapid colour change in U. lineatus.

Sustainable Cellulose-Derived Organic Photonic Gels with Tunable and Dynamic Structural Color.

Structural color is a fascinating optical phenomenon arising from intricate light-matter interactions. Biological structural colors from natural polymers are invaluable in biomimetic design and sustainable construction. Here, we report a renewable, abundant, and biodegradable cellulose-derived organic gel that generates stable cholesteric liquid crystal structures with vivid structural colors. We construct the chromatic gel using a 68 wt % hydroxypropyl cellulose (HPC) matrix, incorporating distinct polyethylene glycol (PEG) guest molecules. The PEGs contain peculiar end groups with tailored polarity, allowing for precise positioning on the HPC helical backbone through electrostatic repulsion between the PEG and HPC chains. This preserves the HPC's chiral nematic phase without being disrupted. We demonstrate that the PEGs' polarity tunes the HPC gel's reflective color. Additionally, gels with variable polarities are highly sensitive to temperature, pressure, and stretching, resulting in rapid, continuous, and reversible color changes. These exceptional dynamic traits establish the chiral nematic gel as an outstanding candidate for next-generation applications across displays, wearables, flexible electronics, health monitoring, and multifunctional sensors.

Phototuning structural color and optical switching cholesteric textures in azobenzene-doped cholesteric liquid crystals

The first integration of structure modulation and phase modulation of CLCs has been accomplished. CLCs doped with azobenzene show rapid color shifts and phase modulation dependent on different intensity light source stimuli within a few seconds.

Radiochromic semiconductive MOFs with high sensitivity and fast photochromic responses for dual-mode X-ray direct detection

A radiochromic semiconductor detector for dual-mode direct X-ray detection, showing rapid color changes and high sensitivity upon X-ray exposure, is reported. This allows quickly capturing object information through visual inspection and serves as an alternative means of direct X-ray detection.

Tunable photo/thermochromic properties of Cd(II)-viologen coordination polymers modulated by coordination modes for flexible imaging films and anti-counterfeiting.

Two photochromic Cd(II)-CPs were obtained based on the viologen ligand using different synthetic routes, named {[Cd4(p-BDC)4(CPB)2(H2O)2]·2H2O·EtOH}n (1) and {[Cd(p-BDC)(CPB)(H2O)]·(L)·DMF}n (2) (p-H2BDC = 1,4-benzene-dicarboxylate, HCPB·Cl = 1-(4-carboxyphenyl)-4,4'-bipyridinium·Cl, L = 2,4-dinitrochlorobenzene, and DMF = N,N-dimethylformamide), respectively. Due to different coordination modes, the two Cd(II)-CPs show different structures. Compound 1 exhibits a three-dimensional (3D) framework with bimetallic nodes, while compound 2 displays a 2-fold interpenetrated (4,4) net topology. Notably, the two Cd(II)-CPs exhibit substantial disparities in photo/thermochromism, which can be attributed to variations in donor-acceptor (D-A) distances arising from structural differences. Compound 1 showed visually sensitive photo- and thermochromic behavior due to multi-pathway electron transfer and short D-A distances, which is relatively rare in electron-transfer type photochromic systems. In contrast, 2 only demonstrates insensitive photochromic behavior, with a slight deepening of the color observed after 2 hours of UV light, which is due to the mono-pathway electron transfer and long D-A distance. Moreover, we first combined Cd(II)-viologen CPs with polydimethylsiloxane (PDMS) to prepare a 1@PDMS flexible UV imaging film. 1@PDMS exhibits excellent bendability and stretchability and maintains good photochromic properties after 100 bending cycles. To demonstrate the rapid color response and distinct color contrast of 1, its application in anti-counterfeiting is also demonstrated.

UV-induced oxidase activity of carbon dots in visible UVA dosage, Escherichia coli quantification and bacterial typing

Ultraviolet (UV) light and foodborne pathogenic bacteriais are an important risk to the environment's safety. They endanger human health, and also lead to outbreaks of infectious disease, posing great threats to global public health security, national economy, and social stability. The appearance of carbon dot (CD) nanozymes offers a new perspective to solve the problems of detection of UV light and pathogenic bacteria in environment. This paper reports the preparation of CDs with dual enzyme-like activities (superoxide dismutase activity and UV-induced oxidase activity). The product can catalyze the oxidation of the substrate 3, 3′, 5, 5′-tetramethylbenzidine (TMB) under UV light (365 nm) to achieve rapid color development. Based on the excellent fluorescence properties of CDs, the colorimetric-fluorescence dual-channel real-time detection of UVA dose was realized, the mechanism underlying the catalytic oxidation of TMB by UV-induced oxidase CDs was also investigated. Furthermore, a portable CDs-TMB-PA hydrogel was prepared which could realize the real-time monitoring of UV in outdoor environment with the assistance of smartphone. Based on the pH dependency of the CD nanozymes and specific glycolytic response of the pathogenic bacteria Escherichia coli (E. coli) O157:H7, the direct, simple, quick, and sensitive typing and detection have been realized. This research offers new perspectives for studying CD nanozymes and their applications in UV and bacterial detection, demonstrating the remarkable potential of CD nanozymes in detecting environmental hazards.

Optimizing cellulose nanofiber composite for Co2+ ions recovery from lithium-ion battery wastes and removal from wastewater: A green environmental solution

In this study, we have introduced an advanced composite material that combines the remarkable properties of cellulose nanofibers (CNFs) with a tailored surface to enable the concentration, spectrophotometric detection, removal of Co2+ ions from wastewater samples and recovery of Co2+ ions from lithium-ion battery waste. CNFs, known for their eco-friendly nature and exceptional surface characteristics, serve as an ideal substrate for immobilizing the (3,3′-((1E,1′E)-((4-nitro-1,2-phenylene) bis(azaneylylidene)) bis(methaneylylidene)) bis(2-hydroxybenzoic acid) (NAMH) chromophoric ligand. The resulting CNFs-NAMH composite displays extraordinary sensitivity to Co2+ ions in aqueous solutions, achieving an impressive limit of detection (LOD) as 0.87 ppb. This exceptional sensitivity allows for straightforward visual detection with the naked eye.A noteworthy feature of the CNFs-NAMH composite is its rapid and distinct color change in approximately a minute upon exposure to varying concentrations of Co2+ ions. Moreover, this composite demonstrates high efficiency in removing Co2+ in polluted wastewater samples and recovering Co2+ ions from lithium-ion batteries, with a high efficiency of up to 79.5 % for Co2+ ions recovery from lithium-ion batteries and removal efficiency of 97.35 % for Co2+ from wastewater samples. This capability addresses critical environmental concerns associated with wastewater treatment and lithium-ion battery waste and provides a practical and sustainable approach for reclaiming valuable Cobalt ions.

Colour change and colour phases in Lethrinidae with insights into ecology.

Colour change is used by a wide range of animals. It is used for intra- and interspecific communication and crypsis, and can occur on morphological and physiological levels. Bony fish employ rapid physiological colour change and display various types of patterns and colouration (colour phases) useful for aposematic and cryptic purposes. Using an existing database of benthic stereo-baited remote underwater video systems from two locations in Western Australia, we tested whether the frequency of colour phases of emperors, Lethrinidae, varied by species. We described colour phases and rapid physiological colour change in 16 species of lethrinids, and related occurrences of colour change to feeding activity and life stages. Dark and light colour phases were observed in nine of the 16 evaluated species of which seven also displayed physiological colour change. Frequency of colour phases varied between species, suggesting that the display of different dark patterns may be especially important for certain species. Both juveniles and adults showed the ability to change between different colour patterns. The change into a mottled pattern mainly occurred while feeding or when approaching to feed, suggesting that it may be triggered by feeding and the associated decrease in environmental awareness. Colour change is a commonly observed strategy in lethrinids and may have evolved as an adaptation for increased foraging success or to reduce aggression from conspecifics. Physiological colour change allows lethrinids to quickly adapt to various cues from the environment and can therefore be considered a versatile physiological mechanism in this family.

Colorimetric and fluorometric bimodal amine chemosensor based on deprotonation-induced intramolecular charge transfer: Application to food spoilage detection

Amine derivatives are signature organic compounds generated from rotten protein food. Thus, sensitive detection of the presence of amines in protein foods can be a critical technique for monitoring their quality. In this study, we develop an organic chemosensor probe, 4-(2-(3-(dicyanomethylene)− 5,5-dimethylcyclohex-1-en-1-yl)vinyl)-N,N-diethylbenzenaminium chloride (DEAH), to effectively detect amines through discernible bimodal (colorimetric and fluorometric) changes. By exploiting the amine-triggered intramolecular charge transfer behavior, DEAH exhibits rapid color changes (<1 s) with an excellent detection limit (36.9 nM) and also fluorescence turn-on in response to amine gas. Moreover, it possesses detection capabilities in versatile conditions, including solutions, solids, and coated films, suggesting its practical applicability. In particular, DEAH shows dramatic color change from yellow to violet with exceptional color difference (△Eab) over 98, repeatable usability, and excellent selectivity to amines. Based on these compelling advantages, we successfully demonstrate real-time monitoring of amine gas generated from spoiled protein foods using DEAH-coated films.

Exploration of bigel 4D printing with spontaneous colour change for monitoring bio-actives kinetic behaviour based on the dual-units 3D printer

This work studied the effect of storage at different temperatures on the relationship between the colour change and bio-actives (curcumin and β-carotene) content change in the bigels 3D printing products. At relatively low temperatures (4 °C and 15 °C), β-carotene degraded rapidly, but a* changed slowly because of less migration of curcumin, indicating that colour change cannot be used for monitoring bio-active changes. At relatively high temperatures (25 °C and 35 °C), the β-carotene degradation fractions reached 0.924 and 0.967. Meanwhile, a* increased to 7.318 and 11.710 while the curcumin migration fraction increased quickly, which indicated that changes in colour and bio-actives content had high consistency at 25 °C and 35 °C. At these temperatures, the bigels 3D printing product lost structure stability due to the high freedom of moisture in hydrogel and increased mobility of oleogel, leading to rapid colour change and fast molecular movement of curcumin and β-carotene.

Photochromic ceramics for multimode detection of UV-VIS radiation dose

Electromagnetic radiation in the ultraviolet-to-visible (UV-VIS) band is closely related to human life, and therefore, accurate measurement of UV-VIS radiation dose is essential. However, there are disadvantages to existing radiation dose equipment: it is cumbersome to operate, takes time to analyze, and lacks multimodal measurements. In this study, a photochromic ceramic with rare earth ions Ho3+ and Yb3+ co-doped Ca2SnO4 host was developed. It produces rapid color switching between light yellow and black under UV and VIS radiation. The XPS and EPR results indicate that oxygen vacancies are important in coloring. Based on the photochromic effect, the intensity of down and up-conversion luminescence can be regulated. The maximum regulation rate is 95 %, higher than most photochromic materials of the same type. A multimode UV-VIS radiation detection method is proposed based on photochromism, down-conversion, and up-conversion luminescence light intensity modulation. The results show that the ceramics respond to a wide spectral range of electromagnetic radiation from UV-VIS with varying degrees, and the best response is to UVB (Ultraviolet Radiation B). A convenient scheme for on-site radiation dosimetry by colorimetry and changes in luminescence intensity was designed to verify the method's reliability. Stability tests have shown that these ceramics have good cyclic stability, making them an ideal detection material for accurate UV-VIS radiation dose detection.

Stable and rapid thermochromic reversibility in acene alkylamine intercalated layered hybrid perovskites

Since the discovery of thermochromism in halide perovskites, new perovskite materials with excellent thermochromic properties have been developed. Among them, two-dimensional (2D) layered hybrid perovskites have been extensively explored because of their highly tunable structures and unique thermochromic responses. In this study, the thermochromism in acene alkylamine-spaced 2D perovskite single crystals (PEA)2PbI4 and (NEA)2PbI4 (PEA = 2-phenylethylammonium, NEA = 2-(2-naphthyl)-ethanammonium) is studied. These 2D perovskites undergo a distinct color change between orange and red during heating and cooling cycles, with the corresponding optical bandgap modulation monitored by variable-temperature absorption spectroscopy. The thermochromism in (PEA)2PbI4 and (NEA)2PbI4 is caused by lattice expansion, as confirmed by thermogravimetric–differential scanning calorimetry and variable-temperature powder X-ray diffraction. Compared with the thermochromism caused by structural phase transition, lattice-expansion-modulated thermochromism demonstrates rapid color change and luminescence recovery, and enhanced thermal cycling stability. This study presents a new strategy for developing thermochromic halide perovskites for multifunctional applications.

Gelatin nanofibers with black elderberry, Au nanoparticles and SnO2 as intelligent packaging layer used for monitoring freshness of Hake fish

The electrospun gelatin nanofibers containing black elderberry (BE) extract, Au nanoparticles (AuNPs) and SnO2 were fabricated as intelligent packaging layer for Hake fish (Merluccius merluccius) fillets. Image analysis confirmed the formation of continuous ultrafine fibers. Differences between nanofibers were evaluated in terms of thermal stability, and chemical composition during storage. Fourier transform infrared spectrums indicated strong bonding interactions between gelatin and other compounds. Thermal analysis results showed that the addition of AuNPs contributed to the thermal stabilization of the gelatin chain. L, a, and b values of nanofibers were also measured. A rapid color change occurred after exposure to volatiles with the highest difference in L (52.29 %) of the sample containing gelatin, BE, SnO2 and AuNPs (p < 0.05). This study showed that the absorption of volatiles on nanofibers can be detected from color changes of nanofibers. The outcomes of this study can be applied for intelligent packaging layer in seafood products.

9 Exploration of Predictors of Cognitive Flexibility Performance in Long-Term Survivors of Childhood Brain Tumor

Objective:Survivors of childhood brain tumor are historically thought to perform worse on measures of executive functioning, including cognitive flexibility (CF; e.g., set-shifting), when compared to their peers. Commonly utilized measures, such as subtests from the Delis-Kaplan Executive Function System (D-KEFS), have baseline conditions that attempt to measure performances independent of but critical for CF tasks (e.g., motor speed on trail making, letter fluency on verbal fluency). However, in research, conditions measuring CF are often included in analyses without accounting for these important baseline conditions. The aim of the current study is to explore differences in CF performance between survivors and their healthy peers when controlling for baseline conditions. The variance explained by each baseline condition on CF condition performance in survivors is also explored.Participants and Methods:A sample of 107 long-term survivors of childhood brain tumor (Mage=21.81, SD=5.99, 50.5% female) and 142 healthy controls (Mage= 23.25, SD=6.61, 61.3% female) were administered the Trail Making Test (TMT), Color-Word Interference (CWI), and Verbal Fluency (VF) subtests from the D-KEFS. For the TMT, baseline conditions include visually scanning for a target, motor speed, and letter and number sequencing. For the CWI subtest, baseline conditions include rapid color naming, word reading, and reading words in a different colored ink. On the VF subtest, baseline conditions include rapidly naming words with a specific letter and from a specific category. An analysis of covariance was conducted for each subtest to determine if groups differed in performance on the CF condition (i.e., Number-Letter Switching, Inhibition/Switching, Category Switching Accuracy) when controlling for baseline conditions. In survivors only, linear regressions investigated the amount of variance explained by each baseline condition on the CF conditions of each subtest.Results:Groups did not differ in CF performance of each subtest when controlling for baseline conditions (ps&gt;.10). Across subtests, baseline conditions significantly predicted CF performance in survivors. On the TMT, Letter Sequencing (p=.003, unique-R2=.05), but not Visual Scanning, Number Sequencing, or Motor Speed, was a significant predictor of Number-Letter Sequencing performance (p&lt;.001, R2=.50). On the CWI subtest, Word Reading (p&lt;.001, unique-R2=.09) and Inhibition (p&lt;.001, unique-R2=.05), but not Color Naming, were significant predictors of Inhibition/Switching performance (p&lt;.001, R2=.67). On the VF subtest, Letter Fluency (p=.009, unique-R2=.06) and Category Fluency (p&lt;.001, unique-R2=.08) were significant predictors of Category Switching Accuracy performance (p&lt;.001, R2=.37).Conclusions:Findings suggest that CF may not differ between survivors and their healthy peers, but that other factors of executive functioning, such as processing speed, drive performance differences on measures of CF. As these tasks rely heavily on speed, survivors may be slower than their healthy counterparts, but may not perform worse on set-shifting. In addition, these results highlight the importance of controlling for lower-order processes in analyses to help isolate CF performance and more accurately characterize potential differences between groups. While replication of findings in survivors and other clinical groups (e.g., congenital heart disease, traumatic brain injury) is still needed, this work can help inform which processes are most important to account for, which is not yet established.

β-Cyclodextrin capped ZnS nanoparticles for CER-assisted colorimetric and spectrophotometric detection of Pb2⁺, Cu2⁺, and Hg2⁺ in an aqueous solution

Herein, simple, low-cost, and room-temperature synthesis of beta-cyclodextrin (β-CD) stabilized zinc sulfide nanoparticle (ZnS NP) through the chemical precipitation method has been reported for cation exchange reaction (CER) based colorimetric sensing of Pb2+, Cu2+, and Hg2+. Formation of β-CD stabilized ZnS NPs (ZnS@β-CD) was verified by physicochemical characterization techniques such as XRD, XPS, FE-SEM, and TEM. ZnS@β-CD NPs showed color change selectively for the metal ions Pb2⁺, Cu2⁺, and Hg2⁺ among the various metal ions including Sn2⁺, Cr³⁺, Mn2⁺, Fe³⁺, Co2⁺, Ni2⁺, and Cd2⁺. The solubility product of reactants and the transformed products are the reason for selective CER of ZnS@β-CD NPs towards Pb2⁺, Cu2⁺, and Hg2⁺ ions. ZnS@β-CD NPs dispersion revealed rapid color change from white to orange, black, and bright yellow on the addition of higher concentrations of Pb2⁺, Cu2⁺, and Hg2⁺ respectively. This color change is due to the formation of complete CER-transformed nanostructures such as PbS, CuS, and HgS in higher concentrations (10⁻1- 10⁻³ M) of corresponding metal ions. The partial CER altered products Zn1−x,PbxS, Zn1−xCuxS and Zn1−xHgxS were detected due to the appearance of pale color in the lower metal ions concentrations of 10⁻⁴ - 10⁻⁶ M. This CER assisted transformation was also monitored through spectrophotometric methods. Moreover, infrared spectroscopic analysis was used to testify the structure of CER transformed product. The synthesized ZnS@β-CD NPs act as an efficient CER-based sensor for distinguishing and determining Pb2⁺, Cu2⁺, and Hg2⁺ at different level concentrations in the aqueous solution.

Assessment of color and contact angle change of weathered wood in relation to wood species and different coating types

Color change was compared through artificial and outdoor weathering tests according to wood species and stain type. In the artificial weathering tests, the color change DE was the highest for the initial 200 hour, and teak solvent-based stain was the most effective in preventing color change. Outdoor weathering tests also showed a rapid color change until the initial 60 days, and the uncoated larch specimens exhibited graying after 120 days. Teak solvent-based stain had the highest preventing color effect, whereas water-based white semi-transparent stain had the highest contact angle. It is difficult to check the color change of wood due to the addition of pigment in teak, as its resistance to moisture is rapidly reduced and its surface protection effect is poor. Water-based white semi-transparent stain prevented color change and maintained a contact angle of 57.1° for up to 150 days, confirming the effect of moisture resistance. This study aimed to provide basic data on weather resistance by wood species and to suggest that the development direction of outdoor exposed wood is a water-based semi-transparent stain.

A Facile Method to Fabricate an Enclosed Paper-Based Analytical Device via Double-Sided Patterning for Ionic Contaminant Detection.

Microfluidic paper-based analytical devices (μPADs) have been developed for use in a variety of diagnosis and analysis fields. However, conventional μPADs with an open-channel system have limitations for application as analytical platforms mainly because of the evaporation and contamination of the sample solution. This study demonstrates the design and fabrication of an enclosed three-dimensional(3D)-μPAD and its application as a primary early analysis platform for ionic contaminants. To generate the hydrophobic PDMS barrier, double-sided patterning is carried out using a PDMS blade-coated stamp mold that is fabricated using 3D printing. The selective PDMS patterning can be achieved with controlled PDMS permeation of the cellulose substrate using 3D-designed stamp molds. We find the optimal conditions enabling the formation of enclosed channels, including round shape pattern and inter-pattern distance of 10 mm of stamp design, contact time of 0.5 min, and spacer height of 300 µm of double-sided patterning procedure. As a proof of concept, this enclosed 3D-μPAD is used for the simultaneous colorimetric detection of heavy metal ions in a concentration range of 0.1-2000 ppm, including nickel (Ni2+), copper (Cu2+), mercury (Hg2+), and radioactive isotope cesium-137 ions (Cs+). We confirm that qualitative analysis and image-based quantitative analysis with high reliability are possible through rapid color changes within 3 min. The limits of detection (LOD) for 0.55 ppm of Ni2+, 5.05 ppm of Cu2+, 0.188 ppm of Hg2+, and 0.016 ppm of Cs+ are observed, respectively. In addition, we confirm that the analysis is highly reliable in a wide range of ion concentrations with CV values below 3% for Ni2+ (0.56%), Cu2+ (0.45%), Hg2+ (1.35%), and Cs+ (2.18%). This method could be a promising technique to develop a 3D-μPAD with various applications as a primary early analysis device in the environmental and biological industries.

Rapid and reversible humidity-dependent colour change by water film formation in a scaled springtail.

Colour is often not a static trait but can change over time either through biotic or abiotic factors. Humidity-dependent colour change can occur through either morphological change (e.g. to feather barbules in birds) or by the replacement of air by water causing a shift in refractive index, as seen in arthropod multi-layer cuticles or scales. The scaled springtail Lepidocyrtus cyaneus has scales that produce colour largely via thin film interference from their lamina. We observed a marked colour change from golden to violet/purple coloration in humid conditions. Light microscopy, micro-spectrophotometry, contact angle goniometry and optical modelling indicate that the formation of a thin film of water on top of the hydrophilic scales increases their laminar thin film thickness, causing a shift towards violet/purple colour. Evaporation of the water film causes the metallic golden colour to return. This constitutes a remarkably rapid colour change (in the order of seconds), only limited by the speed of water film condensation and evaporation, that may serve as inspiration for new dynamically coloured materials and sensors.

Genome-wide association study (GWAS) analysis of black color trait in the leopard coral grouper (Plectropomus leopardus) using whole genome resequencing

The leopard coral grouper (Plectropomus leopardus) is a coral reef fish species that exhibits rapid and diverse color variation. However, the presence of melanoma and the high proportion of individuals displaying black color in artificial breeding have led to reduced economic and ornamental value. To pinpoint single nucleotide polymorphisms (SNPs) and potential genes linked to the black pigmentation characteristic in this particular species, This study gathered a cohort of 360 specimens from diverse origins and conducted a comprehensive genome-wide association analysis (GWAS) employing whole-genome resequencing. As a result, 57 SNPs related to the black skin trait were identified, and a grand total of 158 genes were annotated within 50 kb of these SNPs. Subsequently, GWAS was applied to three populations (LED, QHH, and QHL), and the corresponding results were compared with the analysis results of the total population. The results of the four GWAS models showed significant enrichment in Rap1 signaling pathway, melanin biosynthesis, metabolic pathways, tyrosine metabolism, cAMP signaling pathway, AMPK signaling pathway, PI3K-Akt signaling pathway, EGFR tyrosine kinase inhibitor resistance, HIF-1 signaling pathway, Ras signaling pathway, MAPK signaling pathway, etc. (p < 0.05), which were mainly associated with eleven genes (POL4, MET, E2F2, COMT, ZBED1, TYRP2, FOXP2, THIKA, LORF2, MYH16 and SOX2). Significant differences (p < 0.05) were observed in the expression of all 11 genes in the dorsal skin tissue, in 10 genes except COMT in the ventral skin tissue, and in all 11 genes in the caudal fin tissue. These findings imply that the control of body color in the P. leopardus is the result of the joint action of multiple genes and signaling pathways. These findings will contribute to a more profound comprehension of the genetic attributes that underlie the development of black skin in the vibrant P. leopardus, thus furnishing a theoretical foundation for genetic enhancement.