Pigmented Species Research Articles

Genomic basis of melanin-associated phenotypes suggests colour-specific environmental adaptations in tawny owls.

Feathers comprise a series of evolutionary innovations but also harbour colour, a key biological trait known to co-vary with life history or complex traits. Those relationships are particularly true in melanin-based pigmentation species due to known pleiotropic effects of the melanocortin pathway - originating from melanin-associated phenotypes. Here, we explore the molecular basis of melanin colouration and expected co-variation at the molecular level in the melanin-based, colour polymorphic system of the tawny owl (Strix aluco). An extensive body of literature has revealed that grey and brown tawny owl colour morphs differ in a series of life history and behavioural traits. Thus, it is plausible to expect co-variation also at molecular level between colour morphs. To investigate this possibility, we assembled the first draft genome of the species against which we mapped ddRADseq reads from 220 grey and 150 brown morphs - representing 10 years of pedigree data from a population in Southern Finland - and explored genome-wide associations with colour phenotype. Our results revealed putative molecular signatures of cold adaptation strongly associated with the grey phenotype, namely, a non-synonymous substitution in MCHR1, plus 2 substitutions in non-coding regions of FTCD and FAM135A whose genotype combinations obtained a predictive power of up to 100% (predicting grey colour). These suggest a molecular basis of cold environment adaptations predicted to be grey-morph specific. Our results potentially reveal part of the molecular machinery of melanin-associated phenotypes and provide novel insights towards understanding the functional genomics of colour polymorphism in melanin-based pigmented species.

Kapadokya’daki Post-Bizans (XIX yüzyıl) Kilisesindeki Duvar Resimlerindeki Pigmentlerin Arkeometrik Teknikler ile Araştırılması

Cappadocia region, rock churches, monasteries, houses, underground settlements, valleys and historical and geological formations have unique beauty. The region, which is rich with its cultural assets belongs to Christian culture in Anatolia, is generally known with its rock churches, and is a subject to researches. The purpose of this study is; to understand the wall painting technology of the 19th century church, and to make a comparison with the wall painting materials of the rock churches. The study material is composed of pigments in the wall paintings of the Church of St. Theodoros Trion, which is from the 19th century, and located in Nevşehir. Scanning Electron Microscope and Energy Distributed Spectrometer (SEM-EDX), X-Ray Diffraction Spectrometry (XRD) and Fourier Transformed Infrared Spectrophotometer (FTIR) are used to determine material characterization of pigments. X-Ray Fluorescence Spectrometer (XRF) analysis method was used in the analysis of the soil structure. As a result of analysis of the wall painting, it has been found that the ultramarine pigment is obtained from the lapis lazuli mineral and the covellite mineral of the covellite blue. In red, the red ochre and the caput mortuum pigment in purple color has been found. In the mineral of different pigment species, bauxite mineral belongs to the region have been detected. Green color, it has been determined that it is obtained from the glauconite and celadonite mineral in the region. According to the research carried out in the region in green color, it has been detected that only this pigment species has been used from the 6th century to the 19th century.

Terahertz Spectroscopic Analysis of the Minium Pigment: Evidence of Low-Temperature Phonon Splitting.

Terahertz spectroscopy has been increasingly utilized as an effective nondestructive tool for the diagnosis, analysis, and restoration of artworks. In particular, in the case of artist's pigments, the terahertz probe reveals the vibrational modes that are unique to a given pigment species under study, motivating the ongoing efforts to establish a comprehensive terahertz spectral database of representative pigments. Standard archived spectra are typically acquired at room temperature and susceptible to spectral broadening, which often renders pigment identification difficult, if not impossible. In this paper, we report the frequencies of the vibrational modes of minium (Pb3O4, red lead) by performing terahertz time-domain spectroscopy at room temperature and also at low temperatures. Clear absorption peaks appear at 54.9, 62.1, 71.3, and 83.9 cm-1 at room temperature and blue-shift as the temperature decreases. In addition, new absorption peaks of 59.8 and 66.4 cm-1 are observed below 150 K, which signify a structural phase transition occurring at 170 K in minium. Our results are expected to enhance our understanding of the vibrational activity of minium and suggest a future direction for how to improve and refine the existing terahertz spectral databases for pigment analysis.

Characteristics of pigment complex of sphagnum mosses of south-belomorian bogs on example of Ilas bog massif

Sphagnum mosses play a significant role in the plant communities of the south-belomorian bogs. The adaptation of these plants to environmental conditions can be traced through changes in the pigment complex. In this work, the content of chlorophylls a and b and carotenoids was determined in some ridge species (Sphagnum fuscum, S. rubellum) and hollow species (S. lindbergii and S. majus) in June and September. An increase in total pigments in species growing on ridges is observed in autumn and that can be explained by the formation of comfortable conditions for photosynthesis. The growth of algal biomass can cause a decrease in the pigment content in the species of hollows.

The occurrence of the cis/trans geometric isomerism of myxoxanthophyll and 4-ketomyxoxanthophyll in the cyanobacterium Anabaena sp. PCC7120.

The cyanobacteria of the genus Anabaena have recently been recognized as a potential source of secondary metabolites of pharmacological and biotechnological importance. In particular, myxoxanthophylls - specific carotenoid glycosides that accumulate in cyanobacterial cells, are attracting increasing interest. Anabaena (Nostoc) sp. PCC7120, a filamentous, mesophilic, nitrogen-fixing cyanobacterium, is a model organism used in biochemical and genetic studies. The carotenoid pool of Anabaena sp. PCC7120 consists of five main species of pigments, namely β-carotene, echinenone, canthaxanthin and two derivatives of myxoxanthophyll: myxoxanthophyll ((3R,2'S)-myxol 2'-fucoside) and 4-ketomyxoxanthophyll ((3S,2'S)-4-ketomyxol 2'-fucoside). Recent findings show that the carotenoid biosynthesis pathway functions in Anabaena sp. PCC7120 cells are affected by environmental factors. Specifically, the balance between β-carotene and ketocarotenoids alters according to the temperature conditions. In this study, a new method, based on single-step liquid adsorption chromatography was developed and applied to separate a fraction containing myxoxanthophyll and 4-ketomyxoxanthophyll from Anabaena sp. PCC7120 cells. It was found that this method allowed a high purity fraction of carotenoid glycosides to be obtained from pigment pools as extracted from cyanobacterial cells. The subsequent analysis using the methods HPLC and LC/MS demonstrated that this fraction consists of a mixture of compounds with different retention times. On the basis of their fragmentation spectra and optical properties, these compounds were identified as geometrical isomers of myxoxanthophyll and 4-ketomyxoxanthophyll, including the dominant all-trans forms and less abundant cis forms. Proposals regarding the structures of myxoxanthophyll isomers are made.

Alterations of Phenylpropanoid Biosynthesis Lead to the Natural Formation of Pinkish-Skinned and White-Fleshed Strawberry (Fragaria × ananassa).

Anthocyanin content is important for both the external and internal fruit quality of cultivated strawberries, but the mechanism of its accumulation in pinkish-skinned and white-fleshed strawberries is puzzling. Here, we found that the factor determining variation in the flesh color was not the FaMYB10 but the FaC4H in the cultivated strawberry Benihoppe and its white-fleshed mutant Xiaobai. Compared with Benihoppe, there was no significant difference in the coding sequence and expression level of FaMYB10 in Xiaobai’s flesh. Instead, the transcription of FaC4H was dramatically inhibited. The combined analyses of transcriptomics and metabolomics showed that the differential genes and metabolites were significantly enriched in the phenylpropanoid biosynthesis pathway. Furthermore, the transient overexpression of FaC4H greatly restored anthocyanins’ accumulation in Xiaobai’s flesh and did not produce additional pigment species, as in Benihoppe. The transcriptional repression of FaC4H was not directly caused by promoter methylations, lncRNAs, or microRNAs. In addition, the unexpressed FaF3′H, which resulted in the loss of cyanidin 3-O-glucoside in the flesh, was not due to methylation in promoters. Our findings suggested that the repression of FaC4H was responsible for the natural formation of pinkish-skinned and white-fleshed strawberries.

Comparison of Bovine and Carp Fish Visual Pigment Photo-Intermediates at Room Temperature.

This paper presents room temperature nanoseconds to milliseconds time-resolved spectra and kinetics of the intermediate states and species of bovine and carp fish rhodopsin visual pigments, which also contained ~5% cone pigments. The nanoseconds to milliseconds range cover all the major intermediates in the visual phototransduction process except the formation of bathorhodopsin intermediate which occurs at the femtosecond time scale. The dynamics of these visual pigment intermediates are initiated by excitation with a 532 nm nanosecond laser pulse. The recorded differences between bovine and carp rhodopsin time-resolved spectra of the formation and decay kinetics of their intermediates are presented and discussed. The data show that the carp samples batho intermediate decays faster, nearly by a factor of three, compared to the bovine samples. The formation and decay spectra and kinetics of rhodopsin outer segments and extracted rhodopsin inserted in buffer solution were found to be identical, with very small differences between them in the decay lifetimes of bathorhodopsin and formation of lumirhodopsin.

Terahertz Spectroscopic Analysis of the Vermilion Pigment in Free-Standing and Polyethylene-Mixed Forms.

Terahertz spectroscopy can be utilized as an effective nondestructive identification tool for the study of artist’s pigments. Consequently, extensive measurements have been conducted on representative pigment species, and a few terahertz spectral databases have been constructed. However, the reported spectra were often acquired from pigment samples mixed with polyethylene at room temperature with low resolution, which often led to low-quality spectra with unresolved overlapping lines further broadened due to thermal effects. Here, we present our study of vermilion (HgS, mercury sulfide) as an illustration of how we can overcome such difficulties by studying free-standing oil-paint samples at room temperature and then by performing low-temperature measurements on polyethylene-mixed samples to minimize line broadening due to thermal effects. Our results identify clearly resolved absorption peaks due to lattice vibrations of vermilion at 40.4, 44.5, and 89.9 cm–1 at 2 K. The temperature dependence of the peak shift and line broadening reveals anharmonic characteristics of these lattice vibrational modes. Our approach will definitely suggest new ways to improve and enhance existing terahertz spectral databases of ancient and modern pigments toward actual analysis, diagnosis, and conservation of heritage artworks.

The genus Phagocata Leidy (Platyhelminthes, Tricladida) in Israel, a new species of Phagocata from Lake Kinneret, and an emended description of Dugesia salina

The genus Phagocata (Platyhelminthes, Tricladida) is represented in Israel by two pigmented species, namely, Phagocata armeniaca (Komárek, 1916), reported previously from Armenia, the Caucasus and eastern Turkey, and more recently known from the constantly cold headwaters of the River Jordan in northern Israel, and Phagocata punctata sp. nov., which was found inhabiting the littoral of the south-eastern shore of Lake Kinneret where there are large seasonal temperature fluctuations. Several samples of both species were collected in different seasons and raised in the laboratory at various temperatures and their habitats, morphology, karyology (2n = 34) and breeding behaviour were compared. The results of cross-breeding experiments are given, with most of the F1 offspring showing a range of patterns of colouration, gut branching and fecundity which were intermediate to those of the parent species. However, crossbreeding also resulted in a small proportion of abnormalities among the F1, and especially the F2, generations, indicating an incomplete reproductive compatibility, but supporting the hypothesis of their common origin. An emended description of Dugesia salina (Whitehouse, 1914), is also given together with karyological data (2n = 16) from material collected from a saline spring, En Sheva (Tabgha), situated on the north-western shore of Lake Kinneret.

Comparison between the Light-Harvesting Mechanisms of Type-I Photosynthetic Reaction Centers of Heliobacteria and Photosystem I: Pigment Site Energy Distribution and Exciton State.

The photosynthetic pigment system on the anoxygenic type-I reaction center of heliobacteria (hRC), which has a symmetrical structure, was analyzed. The excitonic coupling among all of the bacteriochlorophyll g (BChl-g) molecules and chlorophyll a (Chl-a) molecules and the site energy for each pigment were calculated using Poisson-TrESP and the charge density coupling (CDC) methods. The obtained theoretical model reproduced the optical absorption and circular dichroism spectra. It also interpreted the decay-associated spectra upon the photoselective laser excitation, which represent the ultrafast excitation energy migration process, better than the simpler hRC models that assumed constant pigment site energy shifts. Spatial movements of excitation energy on pigments on hRC upon the laser excitation were visualized. The energy dissipation by carotenoid molecules in hRC was also predicted. The hRC model was compared with the model of the reaction center of cyanobacterial photosystem I (PSI), which carries 95 Chl-a on the analogous type-I structure with significantly different amino-acid sequences, pigment species, and output redox powers. It is shown that the locations and site energy values of pigments in hRC resemble those in the core of PSI, except for the red-Chl-a sites, suggesting common functional mechanisms implicated in their evolution.

Influence of TiO2 pigment particles on chromate ion transport in epoxy films

Transport of active species (i.e., ions) leaching from pigment particles incorporated in a polymer matrix is the main mechanism behind the anticorrosive performance of protective coatings. Understanding this mechanism is necessary for the effective design of the systems utilizing pigments less toxic than the most efficient chromate salts. It was demonstrated that anticorrosive pigment particles can themselves facilitate the transport of active species via the pathways formed after pigment leaching from a coating. It was also suggested that other paint components, e.g., certain additives, pigments, and fillers can be involved in the formation of transport pathways. Investigation of the possible influence of inert pigment (TiO2) on creating the pathways for chromate ion transport in polymer coatings was the primary objective of this work. In an experiment mimicking the transport of pigment species (i.e., chromate ions), a model epoxy coating containing particles of a single pigment (TiO2) was exposed to a chromate solution (aqueous, or with the addition of acetone as a polymer swelling agent). It was shown that the chromate ions can be transported in the epoxy film preferentially via the TiO2 particles/polymer matrix interface.

Assessment of Metabolic Profiles in Florets of Carthamus Species Using Ultra-Performance Liquid Chromatography-Mass Spectrometry.

The genus Carthamus is a diverse group of plants belonging to the family Compositae. Florets of Carthamus species exhibit various colors, including white, yellow, orange, and red, which are related to their metabolite compositions. We aimed to investigate the metabolites accumulated in florets of three wild (C. lanatus, C. palaestinus, and C. turkestanicus) and one cultivated (C. tinctorius) species of safflower at three developmental stages. Metabolites were extracted from freeze-dried florets using 70% methanol; qualification and quantification were carried out using liquid chromatography quadrupole time-of-flight mass spectrometry in positive and negative ion modes followed by extraction of the peaks. Fifty-six metabolites, including phenylpropanoids, chalcones, isoflavonoids, flavanones, flavonols, flavones, and other primary metabolites, were identified for the first time in safflower wild species. The orange florets contained high abundances of safflomin A, anhydrosafflor yellow B, and baimaside, whereas white/cream and light-yellow pigmented florets had high abundances of 1,5-dicaffeoylquinic acid, luteolin 7-O-glucuronide, and apigenin 7-O-β-D-glucuronide. The principal component analysis clearly distinguished the samples based on their pigment types, indicating that color is a dominant factor dictating the identity and amount of the metabolites. Pearson correlation data based on levels of metabolites showed that orange and yellow florets were significantly correlated to each other. White and cream pigmented species were also highly correlated. Comparison between three developmental stages of safflower wild species based on their metabolite profile showed inconsistent. The findings of this study broaden the current knowledge of safflower metabolism. The wide diversity of metabolites in safflower materials also helps in efforts to improve crop quality and agronomic traits.

Chromate ion transport in epoxy films: Influence of BaSO4 particles

A transport mechanism of anticorrosive pigment species (i.e. chromates) in polymer films was investigated. This mechanism plays a crucial role in the performance of anticorrosive polymer coatings which relays on leaching of active anticorrosive species from sparingly soluble pigment particles distributed in the coating. Except for anticorrosive pigments other particles are included in coatings such as pigments with different functions or fillers.The goal of this work was to investigate how filler particles with no anticorrosive function (i.e. BaSO4) could be involved in formation of the pathways for chromate ion transport . Polymer films containing BaSO4 particles with different pigment volume concentration (PVC) were exposed to chromate solution allowing migration of chromate species.

Parallelisable non-invasive biomass, fitness and growth measurement of macroalgae and other protists with nephelometry

With the exponential development of algal aquaculture and blue biotechnology, there is a strong demand for simple, inexpensive, high-throughput, quantitative phenotyping assays to measure the biomass, growth and fertility of algae and other marine protists. Here, we validate nephelometry, a method that relies on measuring the scattering of light by particles in suspension, as a non-invasive tool to measure in real-time the biomass of aquatic micro-organisms, such as microalgae, filamentous algae, as well as non-photosynthetic protists. Nephelometry is equally applicable to optic density and chlorophyll fluorescence measurements for the quantification of some microalgae, but outperforms other spectroscopy methods to quantify the biomass of biofilm-forming and filamentous algae, highly pigmented species and non-photosynthetic eukaryotes. Thanks to its insensitivity to the sample's pigmentation, nephelometry is also the method of choice when chlorophyll content varies between samples or time points, for example due to abiotic stress or pathogen infection. As examples, we illustrate how nephelometry can be combined with fluorometry or image analysis to monitor the quantity and time-course of spore release in fertile kelps or the progression of symptoms in diseased algal cultures.

Anticorrosion coatings based on novel acrylate binders containing MeO nanoparticles

Abstract Water based paints are increasingly attracting interest mainly with a view to reducing air pollution with volatile organic compounds (VOC). However, the protective properties of water-based paints are inferior to those of solvent-based paints and so new ways to increase the resistance of water-based systems are sought. The present contribution describes the preparation and testing of environmentally friendly anti-corrosion paints based on novel water-based self-crosslinking acrylate latexes containing appropriate pigments and ZnO or MgO nanoparticles at a concentration of 1.5 % (with respect to the monomers) compared to the same systems free from the nanoparticles. Both the effect of the MeO nanoparticles and the effects of the pigment species and particle shapes on the paint film properties were examined. The MeO nanoparticles were found to improve all the properties tested. The latexes with MgO exhibited the highest resistance to flash corrosion while the latexes with ZnO exhibited the highest anticorrosion resistance. Furthermore, the systems with the calcium-aluminium polyphosphosilicate based pigment were superior to all the remaining systems in this respect. It is concluded that binders with nanoparticles can be used as a basis for anticorrosion coatings provided that a suitable pigment is selected.

Marine Chitinolytic Pseudoalteromonas Represents an Untapped Reservoir of Bioactive Potential.

Chitin is the most abundant polymer in the marine environment and a nutrient-rich surface for adhering marine bacteria. We have previously shown that chitin can induce the production of antibiotic compounds in Vibrionaceae, suggesting that the discovery of novel bioactive molecules from bacteria can be facilitated by mimicking their natural habitat. The purpose of this study was to determine the glycosyl hydrolase (GH) profiles of strains of the genus Pseudoalteromonas to enable selection of presumed growth substrates and explore possible links to secondary metabolism. Genomic analyses were conducted on 62 pigmented and 95 nonpigmented strains. Analysis of the total GH profiles and multidimensional scaling suggested that the degradation of chitin is a significant trait of pigmented strains, whereas nonpigmented strains seem to be driven toward the degradation of alga-derived carbohydrates. The genomes of all pigmented strains and 40 nonpigmented strains encoded at least one conserved chitin degradation cluster, and chitinolytic activity was phenotypically confirmed. Additionally, the genomes of all pigmented and a few nonpigmented strains encoded chitinases of the rare GH family 19. Pigmented strains devote up to 15% of their genome to secondary metabolism, while for nonpigmented species it was 3% at most. Thus, pigmented Pseudoalteromonas strains have a bioactive potential similar to that of well-known antibiotic producers of the Actinobacteria phylum. Growth on chitin did not measurably enhance the antibacterial activity of the strains; however, we demonstrated a remarkable co-occurrence of chitin degradation and the potential for secondary metabolite production in pigmented Pseudoalteromonas strains. This indicates that chitin and its colonizers of the Pseudoalteromonas genus represent a so far underexplored niche for novel enzymes and bioactive compounds.IMPORTANCE Infectious bacteria are developing and spreading resistance to conventional treatments at a rapid pace. To provide novel potent antimicrobials, we must develop new bioprospecting strategies. Here, we combined in silico and phenotypic approaches to explore the bioactive potential of the marine bacterial genus Pseudoalteromonas We found that pigmented strains in particular represent an untapped resource of secondary metabolites and that they also harbor an elaborate chitinolytic machinery. Furthermore, our analysis showed that chitin is likely a preferred substrate for pigmented species, in contrast to nonpigmented species. Potentially, chitin could facilitate the production of new secondary metabolites in pigmented Pseudoalteromonas strains.

Multi-Modal Compositional Analysis of Layered Paint Chips of Automobiles by the Combined Application of ATR-FTIR Imaging, Raman Microspectrometry, and SEM/EDX.

For the forensic analysis of multi-layered paint chips of hit-and-run cars, detailed compositional analysis, including minor/trace chemical components in the multi-layered paint chips, is crucial for the potential credentials of the run-away car as the number of layers, painting process, and used paints are quite specific to the types of cars, color of cars, and their surface protection depending on the car manufacturer and the year of manufacture, and yet overall characteristics of some paints used by car manufacturers might be quite similar. In the present study, attenuated total reflectance-Fourier transform infrared (ATR-FTIR) imaging, Raman microspectrometry (RMS), and scanning electron microscopy/energy-dispersive X-ray spectrometric (SEM/EDX) techniques were performed in combination for the detailed characterization of three car paint chip samples, which provided complementary and comprehensive information on the multi-layered paint chips. That is, optical microscopy, SEM, and ATR-FTIR imaging techniques provided information on the number of layers, physical heterogeneity of the layers, and layer thicknesses; EDX on the elemental chemical profiles and compositions; ATR-FTIR imaging on the molecular species of polymer resins, such as alkyd, alkyd-melamine, acrylic, epoxy, and butadiene resins, and some inorganics; and RMS on the molecular species of inorganic pigments (TiO2, ZnO, Fe3O4), mineral fillers (kaolinite, talc, pyrophyllite), and inorganic fillers (BaSO4, Al2(SO4)3, Zn3(PO4)2, CaCO3). This study demonstrates that the new multi-modal approach has powerful potential to elucidate chemical and physical characteristics of multi-layered car paint chips, which could be useful for determining the potential credentials of run-away cars.

Photoprotective benefits of pigmentation in the transparent plankton community: a comparative species experimental test.

Plankton live under the countervailing selective pressures of predation and ultraviolet radiation (UVR). In lakes, zooplankton are transparent reducing visibility to predatory fishes but are pigmented in the absence of fishes, hypothetically reducing UVR damage. In the sea, planktivorous fishes are widespread, so plankton typically are transparent and ascend to productive surface waters at night to forage and descend during the day to reduce visibility to predators. However, larvae of some species face the unique constraint of traveling in surface currents in the daytime during migrations between adult and larval habitats. We would expect these larvae to be transparent since companion studies demonstrated increased predation risk of pigmented larvae under strong sunlight. Paradoxically, larvae range from being darkly to lightly pigmented. We hypothesize that some larvae are more heavily pigmented to reduce UVR damage, while other species travelling in subsurface currents with low UVR might be more transparent. Linking larval morphology to depth-dependent selective pressures would add a key element to help improve predictions of larval vertical distributions, which are important for simulating larval transport trajectories. We quantitatively tested the hypothesis that selection may have favored photoprotective pigmentation for larvae in the predominantly transparent plankton community while testing the differential effects of UVA and UVB radiation. We measured larval pigmentation of 12 species of crabs and exposed them to visible light only, visible+UVA, or visible+UVA+UVB in the tropics. Controlling for phylogeny, more pigmented species survived UVR better than less pigmented species, especially on sunnier days, though intraspecific comparisons for four species were equivocal. Most species died even from UVA exposure, which has long been regarded as relatively harmless despite penetrating deeper underwater than UVB. Thus, we demonstrate with a phylogenetically controlled analysis that crab larvae are pigmented in the predominantly transparent planktonic community to protect from UVR, improving our understanding of the selective forces acting on animal coloration and the factors determining planktonic distributions, survival, and dispersal. This linkage of morphology with susceptibility will be important for developing mechanistic models of environmental stress responses to better predict larval dispersal in current and future climates.

Pseudogenization of Mc1r gene associated with transcriptional changes related to melanogenesis explains leucistic phenotypes in Oreonectes cavefish (Cypriniformes, Nemacheilidae)

Organisms that have colonized underground caves encounter vastly different selective pressures than their relatives in above‐ground habitats. While disruption of certain pigmentation genes has been documented in various cave‐dwelling taxa, little is known about wider impacts across pigmentation and other gene pathways. We here study the timeframe and transcriptional landscape of a leucistic and blind cypriniform fish (Oreonectes daqikongensis, Nemacheilidae) that inhabits karst caves in Guizhou, China. Based on data from the mitochondrial ND4, ND5, and Cytb genes, we show that the divergence between O. daqikongensis and its most closely related pigmented species occurred ca. 6.82 million years ago (95% HPD, 5.12–9.01), providing ample time for widespread phenotypic change. Indeed, we found that the DNA sequence of Mc1r (melanocortin‐1 receptor), a key gene regulating the biosynthesis of melanin in most vertebrates, is pseudogenized in O. daqikongensis, caused by a 29 bp deletion in the protein‐coding region. Furthermore, 99,305 unigenes were annotated based on the transcriptome of skin tissue of Oreonectes fish. Among the differentially expressed unigenes, 7,326 (7.4% of the total unigenes) had decreased expression and 2,530 (2.5% of the total unigenes) had increased expression in O. daqikongensis skin. As predicted, the expression of Mc1r and 18 additional genes associated with melanin biosynthesis was significantly downregulated in the skin tissue of O. daqikongensis, but not in its congener. Our results, integrating with other studies on cavefishes, suggest that loss of pigmentation was caused by coding region loss‐of‐function mutations along with widespread transcriptional changes, resulting from extended evolutionary time as a cave‐dwelling form.

The Influence of Heating Mains on Yeast Communities in Urban Soils

The number and species diversity of yeasts in urban soils (urbanozems) affected by heating mains and in epiphytic yeast complexes of grasses growing above them were studied. The number of yeasts in the soil reached 103–104 CFU/g; on the plants, 107 CFU/g. Significant (by an order of magnitude) increase in the total number of soil yeasts in the zone of heating mains in comparison with the surrounding soil was found in winter period. Overall, 25 species of yeasts were isolated in our study. Yeast community of studied urbanozems was dominated by the Candida sake, an eurybiont of the temperate zone and other natural ecotopes with relatively low temperatures, but its share was minimal in the zone of heating mains. In general, the structure of soil and epiphytic yeast complexes in the zones of heating mains differed from that in the surrounding area by higher species diversity and a lower share of pigmented species among the epiphytic yeasts. The study demonstrated that the number and species structure of soil yeast communities in urban soils change significantly under the influence of the temperature factor and acquire a mosaic distribution pattern.