Color Pattern Research Articles

The Art of Scientific Observation: an art-science project on the legacy of Barbara McClintock

Abstract We explore a facet of the scientific method of the Nobel Laureate Barbara McClintock through an artistic process. McClintock’s key scientific insights that she coined the ‘breakage-fusion-bridge cycle’, rest on her observation of maize kernel colors and forms together with the spatial arrangement of chromosomes. These intriguing studies motivated the art project ‘break-fusion-bridge-cycle’ to highlight the role of visual observation in discovery. Four different posters bear irregular diamond shapes with forms reminiscent of X-chromosome shapes and color patterns of the kernels McClintock studied and are inscribed with the words break, fusion, bridge, and cycle using a font type inspired by her drawings of chromosomes. As freely available posters, anyone can experiment with the spatial arrangement of shapes and colors, to reflect on one’s own ability to observe, to make connections and create new insights.

Machine vision–based automatic planning for microdroplet coating trajectory on irregularly shaped regions of metal surfaces

Metal surface coating technology plays a crucial role in various aspects of metal engineering such as enhancing metal oxidation resistance, corrosion prevention, insulation, decoration, and surface performance. This paper presents a machine vision–based automatic planning algorithm for microdroplet coating trajectory on irregularly shaped regions of metal surfaces, aiming to achieve uniform coating on different surface shapes and sizes. First, the process of microdroplet shape changes on metal surfaces is analyzed, the wetting circle diameter of a fully spread microdroplet is estimated, and the distance between two neighboring microdroplets is confirmed. Then, color pattern image processing (region contour extraction, feature point extraction, deburring, and equidistant offset algorithms) and template matching technology are developed to extract coating trajectory contours and accurately locate the workpieces on the workbench. To ensure a smooth and continuous coating trajectory, rational cubic Bézier curves are employed to interpolate the contour feature points, forming C1 continuous curves. Finally, taking into consideration the distance between two neighboring microdroplets, the continuous curves are equidistant offset and equichord discretized to determine the microdroplet locations. The experimental results demonstrate that the proposed algorithm successfully achieves arbitrary workpiece positioning, automatic planning of coating trajectory and uniform microdroplet coating on different surface shapes and sizes.

Psychedelics sea slugs: Observations on colour ontogeny in two nudibranch species from the genus Nembrotha (Doridina: Polyceridae)

In recent decades, thanks to the use of integrated taxonomy, the traditional recognition of a nudibranch species based on observation and colour pattern variation has become increasingly questioned, mainly due to the presence of cryptic and pseudocryptic species complexes. Individuals with the same colour pattern can be genetically identical, but individuals with different colour patterns may also be genetically identical and this variation may instead represent different life stages. But things can get even more complicated. What happens when the same species changes its colour pattern radically as it ages? Here we present two extraordinary examples in species of the genus Nembrotha based on laboratory observation. Specimens of Nembrotha livingstonei Allan, 1933 and Nembrotha yonowae Goethel and Debelius, 1992 were collected in Mozambique and kept in captivity as long as feeding was possible. The results showed that colour patterns in both species changed over time and that this change was linked to diet. Furthermore, species delimitation analysis and comparison of the uncorrected COI pairwise distances of examined specimens from Mozambique and others downloaded from GenBank confirmed that N. yonowae Goether and Debelius, 1992 is a junior synonym of N. cristata Bergh, 1877. Similar studies with laboratory observations are needed on other species of the genus, as they were described on the basis of different colouration, but integrated taxonomy may show different results.

A new species of Cyrtodactylus Gray, 1827 (Squamata: Gekkonidae) from the Thai-Malay Peninsula and the independent evolution of cave ecomorphology on opposite sides of the Gulf of Thailand.

An integrative taxonomic analysis recovers a distinctive new species of the gekkonid genus Cyrtodactylus Gray, 1827 from Satun Province in extreme southern Thailand as the sister species to the Cyrtodactylus intermedius group of southern Indochina, approximately 600 km to the northeast across the Gulf of Thailand. Based on 1449 base pairs of the mitochondrial gene NADH dehydrogenase subunit 2 (ND2) and its flanking tRNAs, the new species, C. disjunctus sp. nov., bears a pairwise sequence divergence from the mean divergences of the intermedius group species ranging from 17.923.6%. Three different principal component analyses (PCA) and a multiple factor analysis (MFA) recover C. disjunctus sp. nov. as a highly distinctive karst cave-adapted species based on morphology and color pattern. Its sister species relationship to the intermedius groupto which it is added herefurther underscores a growing body of analyses that have recovered a trans-Gulf of Thailand connection across the submerged Sunda Shelf between the southern Thai-Malay Peninsula and southern Indochina. Fragmented karstic archipelagos stretching across Indochina have served as foci for the independent evolution of nearly 25% of the species of Cyrtodactylus. The description of C. disjunctus sp. nov. continues to highlight the fact that karstic habitats support an ever-increasing number of threatened site-specific endemics that compose much of the reptile diversity of many Asian nations but, as of yet, most of these landscapes have no legal protection.

Revision of Litoria rothii (Anura: Pelodryadidae) from northern Australia.

Litoria rothii is a widespread pelodryadid frog with a charismatic laughing advertisement call, distributed across the Australian Monsoon Tropics and southern New Guinea. Given its large distribution spanning well-known biogeographic barriers, variation in male advertisement calls and the prevalence of unresolved species complexes in the Australian frog fauna, we examine the genetic, morphological and acoustic diversity in the species from across its range. Our analyses reveal the presence of a previously unrecognised species in western parts of the range of L. rothii sensu lato, which we describe herein as a new species. Litoria ridibunda sp. nov. is distinguished from L. rothii on the basis of paraphyly of nuclear gene trees with L. everetti from Indonesia, colour patterns on the posterior thigh and male advertisement calls. Compared to L. rothii, the new species has a less contrasting pattern on the posterior thigh and a male advertisement call with a greater number of notes per call and a greater call duration. In particular, the magnitude of call differences between the species is highest where the ranges of the two species are in proximity in north-western Queensland. Our study further emphasises the undiagnosed diversity that remains in Australian frogs, even in relatively large, charismatic, frequently encountered species that often share human dwellings.

A new species of Campsurus Eaton, 1868 (Ephemeroptera: Polymitarcyidae) from the Doce River Basin, Brazil.

The male imago of Campsurus mirim sp. nov., an integrant of the C. major species group, is described based on material from a lake at the Rio Doce basin, Southeastern Brazil. It can be distinguished from other species of the group by the following combination of characteristics: small to medium size (body 7.3 mm, forewings 6.1 mm); blackish pigments on dorsum of head widely and strongly marked in fresh material; abdominal color pattern with pale transverse dashes on terga IIIVII; posterior margin of sternum IX triangular at middle; pedestals flat with inner margin broadly rounded and with both posterolateral corners (inner and outer) approximately of the same length, both acute; penes relatively wide and large, ventrally curved on apical and with apex of main lobe slightly twisted.

Safe Zones Analysis for Lateral Column Lengthening Using Weightbearing CT and Distance Mapping

Category: Hindfoot; Midfoot/Forefoot Introduction/Purpose: Lateral column lengthening (LCL) is the cornerstone for flexible, progressive collapsing foot correction. Evans LCL (ELCL) and Hinterman LCL (HLCL) are the most used surgical techniques. ELCL is performed between the anterior and medial facets and endangers specific os-calcis subtypes (OSCT). HLCL passes in a safe zone between the posterior and medial facets and should be suitable for all OSCTs. However, both osteotomies are associated with increased subtalar osteoarthritis, indicating iatrogenic damage. Distance mapping (DM) enables visualization of the relative distance between two articular surfaces using color patterns. This study aims to measure the safe zones for LCL using DM. Methods: Using the Bruckner et al. classification, two raters categorized 134 patients and 200 feet into the four OSCTs. Four angles were measured. The proximal posterior safe zone (PSZ) and distal PSZ angles defined the safe zone for HLCLO; it was measured for all OSCTs. The proximal anterior safe zone (ASF) angle and the distal ASF defined the safe zone for ELCLO. They were measured only in cases where a discontinuity between the two facets exists or in the absence of anterior facet. A statistical comparison between the groups was made Results: The mean proximal PSZ angle was 68+/-7 degrees, the distal PSZ angle was 75+/-5, the Proximal ASZ angle was 89+/-6 degrees, and the distal ASZ angle was 95+/- 5 degrees. There were no statistically significant differences between the OSCTs. In five patients, the PSZ morphology did not allow planning for HLCLO.in 13 cases; the ASZ left insufficient bone stock between the ELCLO and the calcaneal cuboid joint. Conclusion: In this study, we used DM to determine the safe zone for LCL. The high OSCT and morphology variability call for patient-specific LCL preoperative planning. DM could be reliably used to tailor the optimal surgical solution.

A purebred South American breed showing high effective population size and independent breed ancestry: The Chilean Terrier.

The Chilean Terrier is a known breed in Chile that has not been genetically assessed despite its distinctive color patterns, agility, and hardiness across the diversity of climates encountered within the Chilean landscape. The population structure and its relatedness with other breeds, as well as the actual origin of the breed, remain unknown. We estimated several population parameters using samples from individuals representing the distribution of the Chilean Terrier across the country. By utilizing the Illumina HD canine genotyping array, we computed the effective population size (Ne ), individual inbreeding, and relatedness to evaluate the genetic diversity of the breed. The results show that linkage disequilibrium was relatively low and decayed rapidly; in fact, Ne was very high when compared to other breeds, and similar to other American indigenous breeds (such as the Chihuahua with values of Ne near 500). These results are in line with the low estimates of genomic inbreeding and relatedness and the relatively large number of effective chromosome segments (Me = 2467) obtained using the properties of the genomic relationship matrix. Between population analysis (cross-population extended haplotype homozygosity, di ) with other breeds such as the Jack Russell Terrier, the Peruvian-Inca Orchid, and the Chihuahua suggested that candidate regions harboring FGF5, PAX3, and ASIP, probably explained some morphological traits, such as the distinctive color pattern characteristic of the breed. When considering Admixture estimates and phylogenetic analysis, together with other breeds of American and European origin, the Chilean Terrier does not have a recent European ancestry. Overall, the results suggest that the breed has evolved independently in Chile from other terrier breeds, from an unknown European terrier ancestor.

Testing the function of a colour pattern polymorphism in a lizard

Abstract Trait polymorphisms can vary across different contexts of selection and be maintained through trade-offs between these contexts. For example, colour polymorphic variants may represent alternative strategies optimizing crypsis or thermoregulation in different populations. Here we use visual modelling to test the conspicuousness of different colour pattern morphs in males and females of an Australian lizard, Lampropholis delicata, to predators and conspecifics. We further assess differences in reflectance, microhabitat selection, and mate preference to determine the functional role of the polymorphism and explain its variable distribution across latitude and the sexes. Plain morphs are more conspicuous than striped morphs in both bird and lizard visual models, suggesting predation selection, and habitat structure varies among sex-morph types, but we find no difference in microhabitat selection or mate preference based on colour. We suggest that a combination of spatially varying selection, habitat preference, and context-specific behaviour may be necessary to explain spatial patterns of colour morph frequencies.

Hierarchical morphogenesis of swallowtail butterfly wing scale nanostructures

The study of color patterns in the animal integument is a fundamental question in biology, with many lepidopteran species being exemplary models in this endeavor due to their relative simplicity and elegance. While significant advances have been made in unraveling the cellular and molecular basis of lepidopteran pigmentary coloration, the morphogenesis of wing scale nanostructures involved in structural color production is not well understood. Contemporary research on this topic largely focuses on a few nymphalid model taxa (e.g., Bicyclus, Heliconius), despite an overwhelming diversity in the hierarchical nanostructural organization of lepidopteran wing scales. Here, we present a time-resolved, comparative developmental study of hierarchical scale nanostructures in Parides eurimedes and five other papilionid species. Our results uphold the putative conserved role of F-actin bundles in acting as spacers between developing ridges, as previously documented in several nymphalid species. Interestingly, while ridges are developing in P. eurimedes, plasma membrane manifests irregular mesh-like crossribs characteristic of Papilionidae, which delineate the accretion of cuticle into rows of planar disks in between ridges. Once the ridges have grown, disintegrating F-actin bundles appear to reorganize into a network that supports the invagination of plasma membrane underlying the disks, subsequently forming an extruded honeycomb lattice. Our results uncover a previously undocumented role for F-actin in the morphogenesis of complex wing scale nanostructures, likely specific to Papilionidae.

Hierarchical morphogenesis of swallowtail butterfly wing scale nanostructures.

The study of color patterns in the animal integument is a fundamental question in biology, with many lepidopteran species being exemplary models in this endeavor due to their relative simplicity and elegance. While significant advances have been made in unraveling the cellular and molecular basis of lepidopteran pigmentary coloration, the morphogenesis of wing scale nanostructures involved in structural color production is not well understood. Contemporary research on this topic largely focuses on a few nymphalid model taxa (e.g., Bicyclus, Heliconius), despite an overwhelming diversity in the hierarchical nanostructural organization of lepidopteran wing scales. Here, we present a time-resolved, comparative developmental study of hierarchical scale nanostructures in Parides eurimedes and five other papilionid species. Our results uphold the putative conserved role of F-actin bundles in acting as spacers between developing ridges, as previously documented in several nymphalid species. Interestingly, while ridges are developing in P. eurimedes, plasma membrane manifests irregular mesh-like crossribs characteristic of Papilionidae, which delineate the accretion of cuticle into rows of planar disks in between ridges. Once the ridges have grown, disintegrating F-actin bundles appear to reorganize into a network that supports the invagination of plasma membrane underlying the disks, subsequently forming an extruded honeycomb lattice. Our results uncover a previously undocumented role for F-actin in the morphogenesis of complex wing scale nanostructures, likely specific to Papilionidae.

Standardization of processing parameters and color of gels aiming to replace citric pectin by mesocarp flour or pectin of passion fruit

The processing of passion fruit generates a huge quantity of wastes, reaching 50% in mass of rind. The main use of the rinds is to produce rind flour or to be source of pectin as a gelling agent. This work develops a standard procedure to evaluate jelly products subjected to the same temperature histories and content of soluble solids along the processing time of the gel-based product, using different concentrations of mesocarp flour and pectin. The gels were evaluated by color patterns aiming to verify the applicability of mesocarp flour as substitute of commercial pectin in jelly of fruits. The quantitative analysis of the data for temperature histories and content of soluble solids enabled to confirm the standardization of the parameters used in the production of the gels, which is important to warrant the same processing conditions during the elaboration of the different types of gels. The gels made with passion fruit’s mesocarp flour have less translucent shades and a more yellowish color than the gels produced with commercial citric pectin, however, these small differences may not interfere in the final color of fruit jelly.

3D-Printed Biomimetic Structural Colors.

Resolution control and expansibility have always been challenges to the fabrication of structural color materials. Here, a facile strategy to print cholesteric liquid crystal elastomers (CLCEs) into complex structural color patterns with variable resolution and enhanced expansibility is reported. A volatile solvent is introduced into the synthesized CLC oligomers, modifying its rheological properties and allowing direct-ink-writing (DIW) under mild conditions. The combination of printing shear flow and anisotropic deswelling of ink drives the CLC molecules into an ordered cholesteric arrangement. The authors meticulously investigate the influence of printing parameters to achieve resolution control over a wide range, allowing for the printing of multi-sized 1D or 2D patterns with constant quality. Furthermore, such solvent-cast direct-ink-writing (DIW) strategy is highly expandable and can be integrated easily into the DIW of bionic robots. Multi-responsive bionic butterfly and flower are printed with biomimetic in both locomotion and coloration. Such designs dramatically reduced the processing difficulty of precise full-color printing and expanded the capability of structural color materials to collaborate with other systems.

A case of leucosis in Heptapterus mustelinus (Siluriformes, Heptapteridae) among populations of streams in southern Brazil. Has leucosis in Heptapterus mustelinus an adaptive value in shaded streams?

Fish populations in environments with a high degree of geographic isolation may be prone to mutations expressed in the phenotypes. These mutations may be related to color pattern, forming leucistic individuals. This work aims to register and to describe possible mechanisms that influence this mutation. Additionally, the study compares other morphometric variations among different populations and leucistic individuals of Heptapterus mustelinus. A total of four leucistic individuals were collected in a small shaded stream, highly segmented by rapids and waterfalls. The biometric analyses showed no significant morphological differences when compared to other populations of the same ecoregion. The selection of leucism may be directly related to the sampled environment, since the leucistic specimens occurred in a shaded stream with dense vegetation cover. Low occurrence of predatory species of fish can be an important point to maintain the characteristic. Consequently, predation may not exert a negative selective pressure on leucistic individuals.

Transcriptomic analysis of colour dimorphism of Opsariichthys bidens provides insights into the mechanism of male colour

Opsariichthys bidens (O. bidens) is a fish species native to China. It has become a popular ornamental fish because of its interesting colour dimorphism. Its colour pattern is unique; however, with the exception of model species, such as zebrafish, the molecular mechanisms of most fish colour patterns remain unclear. In the present study, we compared and analysed the transcriptomic data of the skin and anal fins of male and female O. bidens. A total of 9028 differentially expressed genes (DEGs) were identified, of which 5259 were upregulated and 3769 were downregulated in males. Compared with known pigmentation genes, Mitf, Tyr, Tyrp1, Dct, Pnp4a, Alx4a, Gch1, and Csf1r were identified as potential genes related to colour dimorphism. Second, we tracked the process of colour development in male O. bidens and found that there were three stages in the formation of body colour. We explored the distribution, migration, and expression patterns of genes related to pigment cells at each stage using microscopic imaging, transmission electron microscopy, enzyme-linked immunosorbent assay, and high-performance liquid chromatography. Melanophores, xanthophores, and iridophores were found to be distributed on the skin or anal fins of O. bidens. It was inferred that this unique body colour pattern is caused by the differentiation and migration of pigment cells at specific stages. This discovery provides a basis for studying the molecular mechanisms of pigmentation in ornamental fish and will contribute to the genetic selection and breeding of O. bidens in ornamental fish cultures in the future.

Differential Coloration, Pigment Biosynthesis-Related Gene Expression, and Accumulation According to Developmental Stage in the ‘Enbu’ Apple

Coloration, a major factor contributing to apple quality, attracts consumer attraction, thereby increasing the sale of fruits in the market. Among the fruit pigments, anthocyanins and carotenoids are the most important pigments that impart coloration to apples. Pigment accumulation, which is regulated by transcriptional factors in the anthocyanin and carotenoid biosynthesis pathways, varies according to genetics, transcription, and developmental stage. To understand the regulation of color development in apples, we evaluated the expression of the genes in the anthocyanin and carotenoid biosynthetic pathways and analyzed the accumulation of pigment, including anthocyanin and carotenoid in the skin and flesh of the red-fleshed apple ‘Enbu’ cultivar at different fruit development stages (30, 60, 90, 120, and 150 days after full bloom, and ripe). Color development increased according to the developmental stage, with considerable variation in both the transcript levels and pigment concentrations observed in tissues, skin, and flesh. Moreover, we identified key transcription factors among the anthocyanin and carotenoid biosynthesis genes that regulated pigment accumulation. Pearson’s correlation analysis showed a strong correlation between the coloration patterns and the expression levels of anthocyanin biosynthesis-related genes (MdPAL, MdCHI, and MdF3H) and carotenoid biosynthesis-related genes (MdGGPPS, MdPSY, MdZDS, MdCRTISO, MdCRHβ, and MdZEP). This study provides insight into the molecular mechanisms underlying pigment biosynthesis for breeding high-quality red-fleshed apple varieties to cater to consumer attention and preference.

Water color from Sentinel-2 MSI data for monitoring large rivers: Yangtze and Danube

ABSTRACT Rivers provide key ecosystem services that are inherently engineered and optimized to meet the strategic and economic needs of countries around the world. However, limited water quality records of a full river continuum hindered the understanding of how river systems response to the multiple stressors acting on them. This study highlights the use of Sentinel-2 Multi-Spectral Imager (MSI) data to monitor changes in water color in two optically complex river systems: the Yangtze and Danube using the Forel-Ule Index (FUI). FUI divides water color into 21 classes from dark blue to yellowish brown stemming from the historical Forel-Ule water color scale and has been promoted as a useful indicator showing water turbidity variations in water bodies. The results revealed contrasting water color patterns in the two rivers on both spatial and seasonal scales. Spatially, the FUI of the Yangtze River gradually increased from the upper reaches to the lower reaches, while the FUI of the Danube River declined in the lower reaches, which is possibly due to the sediment sink effect of the Iron Gate Dams. The regional FUI peaks and valleys observed in the two river systems have also been shown to be related to the dams and hydropower stations along them. Seasonally, the variations of FUI in both systems can be attributed to climate seasonality, especially precipitation in the basin and the water level. Moreover, land cover within the river basin was possibly a significant determinant of water color, as higher levels of vegetation in the Danube basin were associated with lower FUI values, whereas higher FUI values and lower levels of vegetation were observed in the Yangtze system. This study furthers our knowledge of using Sentinel-2 MSI to monitor and understand the spatial-temporal variations of river systems and highlights the capabilities of the FUI in an optically complex environment.

The origins of colour patterns in fossil insects revealed by maturation experiments.

Many fossil insects show monochromatic colour patterns that may provide valuable insights into ancient insect behaviour and ecology. Whether these patterns reflect original pigmentary coloration is, however, unknown, and their formation mechanism has not been investigated. Here, we performed thermal maturation experiments on extant beetles with melanin-based colour patterns. Scanning electron microscopy reveals that melanin-rich cuticle is more resistant to degradation than melanin-poor cuticle: with progressive maturation, melanin-poor cuticle regions experience preferential thinning and loss, yet melanin-rich cuticle remains. Comparative analysis of fossil insects with monotonal colour patterns confirms that the variations in tone correspond to variations in preserved cuticle thickness. These preserved colour patterns can thus be plausibly explained as melanin-based patterning. Recognition of melanin-based colour patterns in fossil insects opens new avenues for interpreting the evolution of insect coloration and behaviour through deep time.

Identification of a novel locus C2 controlling canary yellow flesh color in watermelons.

The flesh color of watermelon is an important trait that is determined by carotenoid composition and affects consumers' fruit desirability. Although a complete dominant control by C locus (Cllcyb) for canary yellow flesh (CY) over red flesh has been reported, red and CY colors frequently appear as a mixed pattern in the same flesh (incomplete canary yellow, ICY) in F1 and inbred lines carrying dominant C alleles. Therefore, we examined the genetic control of the mixed color pattern in ICY using whole-genome resequencing of three ICY (ICY group) and three CY inbred lines (CY group), as well as genetic linkage mapping of an F2 population. The segregation pattern in 135 F2 plants indicated that CY is controlled by a single locus (named C 2) dominant over ICY. The whole-genome resequencing of ICY and CY inbred lines revealed an ICY/CY-specific region of approximately 27.60-27.88Mb on Chr. 2 that was polymorphic between the ICY and CY groups. Our genetic map, using nine cleaved amplified polymorphic sequence markers developed based on the single-nucleotide polymorphisms from the ICY/CY-specific region, confirmed that C 2 is located on Chr. 2 and cosegregated with the marker (M7) derived from a non-synonymous single-nucleotide polymorphism of the pentatricopeptide repeat (PPR) gene (ClPPR, Cla97C02G039880). Additionally, 27 watermelon inbred lines of ICY, CY, and red flesh were evaluated using previously reported Cllcyb (C locus)-based markers and our C 2 locus-linked ClPPR-based marker (M7). As a result, dominant alleles at the C 2 locus were required to produce CY, in addition to dominant alleles at the C locus, while a recessive homozygous genotype at the C locus gave the red flesh irrespective of the genotype at the C 2 locus. Using a ClPPR-based cleaved amplified polymorphic sequence developed in this study and Cllcyb-based markers, watermelon cultivars with CY, ICY, and red flesh could be successfully discerned, implying that the combined use of these markers will be efficient for marker-assisted selection of flesh color in watermelon breeding.

Detailed comparison of two close Chinese species, Teloganopsis punctisetae (Matsumura, 1931) and T. jinghongensis (Xu, You and Hsu, 1984) (Ephemeroptera: Ephemerellidae)

ABSTRACT Historically and currently, there have been identification confusions between two closely related species, Teloganopsis punctisetae (= E. changbaishanensis Su and You, 1988, syn. nov.) and T. jinghongensis. This study provides clear digital photographs of numerous external structures of these two species and compares them in detail. Morphologically, the nymphs differ in their colour patterns and leg shapes, while the adults have different hindwings, femora, and penial projections. This comparison not only shows the differences in characteristics between these two similar species but also clarifies the identification of the genus Teloganopsis Ulmer, 1939.