Pigment Complex Research Articles

Structural basis of selective beta-carotene binding by a soluble protein

β-carotene (BCR) is the most abundant carotenoid, a colorant, antioxidant, and provitamin A. The extreme hydrophobicity of this hydrocarbon requires special mechanisms for distribution in aqueous media, including water-soluble carotenoproteins. However, all known carotenoproteins prefer oxygenated carotenoids and bind BCR inefficiently. Here, we present the crystal structure of the BCR-binding protein (BBP) from gregarious male locusts, which is responsible for their vivid yellow body coloration, in complex with its natural ligand, BCR. BBP forms an antiparallel tubular homodimer with α/β-wrap folded monomers, each forming a hydrophobic 47Å long, coaxial tunnel that opens outward and is occupied by one s-cisC6-C7, all-trans BCR molecule. In the BCR absence, BBP accepts a range of xanthophylls, with reduced efficiency depending on the position and number of oxygen atoms, but rejects lycopene. The structure captures a pigment complex with a Takeout 1 protein and inspires potential applications of BBP as a BCR solubilizer.

Anatomical and phytochemical study of Ocimum basilicum L. leaves of two popular varieties in Ukraine

оne of the important sources of flavonoid phytonutrients is basil (Ocimum basilicum L.). Vegetative and generative organs of which have essential oils, in particular 1,8-cineole, estragole and eugenol, ascorbic acid, a rich pigment complex, as well as polyphenolic compounds with antioxidant effects. Basil realizes its antioxidant potential through anthocyanins in varieties with purple leaves and flavonoids in varieties with green leaves. The level of their accumulation, as well as other biologically active substances, depends on the variety to which the plant belongs, the degree and spectrum of illumination, soil moisture, and mineral nutrition (Priss OP, et al., 2019; Joshi RK, 2014; Trichopoulou, et al., 2000). That is why our attention was drawn to two of the most popular basil varieties in Ukraine: "Dolly" with green leaves and "Rosie" with purple leaves. Our research was focused on morphological, anatomical and phytochemical studies of O. basilicum leaves of the above-mentioned raw materials. To realize this goal, microscopy was performed using State Pharmacopoeia of Ukraine methods. Groups of biologically active substances were determined by standard qualitative reactions and the procedure was carried out using extracts or by applying directly to the sections. It was found that O. basilicum chanterelles of "Dolly" and "Rosie" varieties have a number of common and distinctive features. Both varieties of O. basilicum are characterized by the presence of dorsoventral, amphistomatic leaves, diacytic stomatal apparatus and biserial glands. The leaves differ in color, shape of the leaf blade margin, outlines of the upper epidermal cells, presence of idioblast cells with anthocyanins in the "Rosie" variety, and values of stomatal indices. The stomatal index is 27.5±2.3% for the "Dolly" variety and 25.4±2.5% for the "Rosie" variety. It was found that the leaves of O. basilicum varieties "Dolly" and "Rosie" contain such biologically active substances as anthocyanins, flavonoids, essential oil, triterpene saponins, especially expressed in the variety "Rosie" and tannins. The research results can be used in the development of a monograph on the raw materials of this species.

Pigment Complex, Growth and Chemical Composition Traits of Boreal Sphagnum Mosses (Mire System "Ilasskoe", North-West of European Russia).

Sphagnum mosses play a significant role in peat formation and carbon sequestration in mire ecosystems. It is critical to investigate the productivity and chemical composition of different Sphagnum species in order to assess their role in the global carbon cycle and potential in light of climate change. The data on productivity and growth characteristics during the growing season, group chemical composition and elemental composition at the beginning and end of the growing season, as well as aspects of the pigment complex operation, were collected for four Sphagnum species: Sphagnum lindbergii Schimp., S. fuscum (Schimp.) Klinggr., S. divinum Flatberg & K. Hassel, and S. squarrosum Crome. High cover density and productivity, low ability to decompose, and constancy of the pigment complex of S. fuscum reflect a high degree of adaptation to the specific conditions of ridges. A constant chemical composition of S. lindbergii during the growing season can be explained by stable conditions of hollows that allow it to maintain its metabolic processes, but the light conditions in hollows bring the reaction of the pigment apparatus of this species closer to shaded S. divinum and S. squarrosum. S. lindbergii and S. squarrosum contain more nitrogen than other species and have a greater ability to decompose.

Photosystem I enhanced perovskite–Organic tandem solar cell efficiency

Tandem solar cells (TSC) have been introduced to better absorb the spectrum of sunlight and reduce optical loss. Among these, perovskite–organic tandem solar cells (P-OTSC) have emerged as a prominent topic over the last decade due to their complementary absorption spectrum. Additionally, incorporating diverse pigmented protein complexes in TSC fabrication is becoming more common. Natural chlorophyll-containing photosystems have garnered significant attention for their naturally solar-tuned absorption spectra. Photosystem I protein (PSI), is the most robust component of oxygenic photosynthesis and contains over 100 Chl a molecules/complex with two sharp absorbance peaks at 430 and 665 nm. PSI offers a second and complementary active layer because P-OTSCs often have a low extinction coefficient in the red wavelength region. In this research, the performance of P-OTSCs was enhanced by improving the absorption spectrum by utilizing an isolated plant PSI complex. The circuit current density (Jsc) increased from 14.23 mA/cm² to 14.95 mA/cm², and the power conversion efficiency (PCE) of P-OTSCs increased from 19.32 % to 20.24 %. We also observed that the external quantum efficiency (EQE) shows an apparent increase in the long wavelength region, reflecting the absorbance of light by PSI. This work is the first to report the integration of PSI into perovskite–organic tandem solar cells, and it motivates new design considerations that can further boost efficiency and utilize natural, earth-abundant pigment proteins.

Seasonal Changes in the Photosynthetic Pigment Complex of Sphagnum Mosses: The case of Sphagnum papillosum Lindb.

Seasonal Changes in the Photosynthetic Pigment Complex of Sphagnum Mosses: The case of Sphagnum papillosum Lindb.

Effect of TopDressing on Chlorophyll Content in Barley Leaves and Its Relation to Grain Quality Parameters

The effect of top-dressing at tillage phase by Polydon® Amino Start organomineral fertilizer and KAS-28 liquid mineral fertilizer on the state of the leaf pigment complex of spring barley cv. Novichok, Rodnik Prikamya and Pamyati Rodinoy and its relationship with grain quality parameters was studied under field conditions of the Kirov region of the Russian Federation in 2020–2022. Significant effect of top-dress treatments on pigment content in the flag and second leaves was revealed. The use of top-dressing with KAS-28 enhanced the association of grain quality parameters with the chlorophyll pigment content of the two upper leaves compared to the control variant. The effect of Amino Start was not uniform: some of the connections were somewhat weakened compared to the control, some intensified, and some became statistically significant. The total content of chlorophyll correlated with the content of cellulose and fat in the grain in all treatments. Compared to controls, the use of top-dress treatments altered the effectiveness of using of photoassimilates of both leaves for cellulose and fat synthesis. The obtained data indicate the possibility of predicting the content of the main parameters of spring barley’s grain quality by the content of chlorophyll pigments in flag or second leaves of plants during the flowering phase.

THE REMEDIATION METHOD AS A FACTOR SHAPING THE PIGMENT PROFILE OF SCOTS PINE ON TECHNOGENIC LAND

Background. It is important to study how the remediation method influences the formation of the pigment complex in Scots pine, Pinus sylvestris L., growing on technogenic land. Thorough understanding of the influence produced by a heterogeneous environment on the content and distribution of pigments in conifers enables us to study the adaptive mechanisms of the species more comprehensively. In turn, information about these mechanisms can be used to create new methods for improving the quality and stability of tree stands. Purpose. The study was designed to explore the effect of the remediation method on the pigment complex forming in Scots pine during a post-technogenic succession in southern Karelia. Material and methods. Surveys were carried out in adjacent sample plots located in a decommissioned sand-and-gravel quarry and in a natural lingonberry-type pine forest site in July 2021 and 2022. The study objects were Scots pine trees growing in a natural forest site and in quarry sites remediated by forest planting. The optical density of the solutions was determined using SF-2000 spectrophotometer. Statistical data processing was done using Statistica 10 software (StatSoft Inc., USA). Results. During the two years of the study, the pigment content was the highest in needles of the trees growing on more fertile soils compared to those on poor man-made soils. The of Cl a /Cl b ratio in the needles of trees growing on poor soil was higher than in the fertilized area of the quarry or in the natural forest site in both years of the study, indicating that the plants’ pigment complex adapted to the unfavorable environmental conditions by increasing the proportion of Cl a among green pigments. Conclusions. The findings prove that the remediation method has a significant shaping effect on the pigment profile of Scots pine during post-technogenic successions.

SEASONAL CHANGES IN THE CONCENTRATION AND RATIOS OF PHOTOSYNTHETIC PIGMENTS IN THE THREE SPHAGNUM SPECIES

Background. There is reason suppose that the concentration of photosynthetic pigments in sphagnum mosses, as in vascular plants, changes throughout the year and varies from species to species. Moreover, hollow sphagnum species have a higher growth and photosynthesis rate than ridge sphagnum species, which suggests the presence of differences in the pigment complex of species from different habitats. Purpose. Evaluation of quantitative changes in the pigment complex of the sphagnum mosses growing in different microclimatic conditions within oligotrophic bogs during the growing season at high latitudes. Materials and methods. The content of photosynthetic pigments in the three Sphagnum species growing in oligotrophic conditions was determined using the photometric method in an acetone extract once a month from May to October. The study was carried out for S. fuscum and S. lindbergii in 2021-2022, and for S. angustifolium only in 2022. Statistical data processing was carried out in Microsoft Excel 2010 and SPSS Statistics 11. Results. Seasonal and interannual variability in the content of chlorophylls, carotenoids, and their ratios was revealed for the studied sphagnum species. The pigment complex of S. lindbergii and S. angustifolium during the growing season is influenced by the bog water level and air temperature. Changes in the pigment complex of S. fuscum are associated with the amount of precipitation. Conclusion. Apparently, the seasonal and interannual dynamics of the pigment complex of sphagnum mosses is species-specific, but to further verify this statement it is necessary to study other species of sphagnum mosses from the same habitats, since the dynamics may be associated not so much with a peculiar species, but with the ecological conditions of the habitat.

Пигментная система нитчатых цианобактерий в условиях аккумуляции ионов свинца

The effect of Pb (CH3COO)2 solutions with Pb2+ concentrations equal to 0.02, 0.1, 0.2 and 0.4 mM to strain of cyanobacteria (CB) Leptolyngbya sp. SK was studied. The duration of exposure of the culture with solutions was 21 days. During the experiment, measured the loss of lead ions in the solution; the increase in the biomass of CB was assessed as an indicator of culture adaptation; determined the content of photosynthetic pigments as indicators of maintaining the viability of the culture. The content of lead ions decreased in all variants, the maximum decrease was 96.2% – in the medium with a Pb2+concentration of 0.4 mM. An increase in the biomass of CB was observed in the presence of Pb2+ of all concentrations, the maximum increase in a solution with a Pb2+ concentration of 0.1 mM was up to 7.5 times. There was a decrease in the content of chlorophyll a in the biomass of CB, in comparison with the control, by 67.0–94.2% with an increase in the concentration of Pb2+ in the solution. Under the influence of solutions with Pb2+ concentrations of 0.02, 0.1, and 0.4 mM, the content of carotenoids in the biomass of cyanobacteria decreased by 48%, 75% and 92%, respectively; the concentration of Pb2+0.2 mM caused an increase in the content of carotenoids by 1% with the control. The inhibitory effect of all investigated concentrations of Pb2+ was noted on the complex of phycobilin pigments. The accumulation of lead ions from solutions with Pb2+ concentrations up to 0.4 mM, an increase in CB biomass in the presence of 0.1 mM Pb2+ and an increase in the synthesis of carotenoids at 0.2 mM Pb2+ may indicate adaptation of the studied culture to lead acetate.

Changes in the leaf structure and pigment complex of <i>Betula pendula</i> under conditions of technogenic air pollution

Changes in the leaf structure and pigment complex of <i>Betula pendula</i> under conditions of technogenic air pollution

Dynamics of the processes of formation and accumulation of phenolic and pigment complexes in the needles of pine Pinus sylvestris

Dynamics of the processes of formation and accumulation of phenolic and pigment complexes in the needles of pine Pinus sylvestris

Retinal Pigment Epithelium Pigment Granules: Norms, Age Relations and Pathology.

The retinal pigment epithelium (RPE), which ensures the normal functioning of the neural retina, is a pigmented single-cell layer that separates the retina from the Bruch's membrane and the choroid. There are three main types of pigment granules in the RPE cells of the human eye: lipofuscin granules (LG) containing the fluorescent "age pigment" lipofuscin, melanoprotein granules (melanosomes, melanolysosomes) containing the screening pigment melanin and complex melanolipofuscin granules (MLG) containing both types of pigments simultaneously-melanin and lipofuscin. This review examines the functional role of pigment granules in the aging process and in the development of oxidative stress and associated pathologies in RPE cells. The focus is on the process of light-induced oxidative degradation of pigment granules caused by reactive oxygen species. The reasons leading to increased oxidative stress in RPE cells as a result of the oxidative degradation of pigment granules are considered. A mechanism is proposed to explain the phenomenon of age-related decline in melanin content in RPE cells. The essence of the mechanism is that when the lipofuscin part of the melanolipofuscin granule is exposed to light, reactive oxygen species are formed, which destroy the melanin part. As more melanolipofuscin granules are formed with age and the development of degenerative diseases, the melanin in pigmented epithelial cells ultimately disappears.

Efficient two-step excitation energy transfer in artificial light-harvesting antenna based on bacteriochlorophyll aggregates

Chlorosomes of green photosynthetic bacteria are large light-harvesting complexes enabling these organisms to survive at extremely low-light conditions. Bacteriochlorophylls found in chlorosomes self-organize and are ideal candidates for use in biomimetic light-harvesting in artificial photosynthesis and other applications for solar energy utilization. Here we report on the construction and characterization of an artificial antenna consisting of bacteriochlorophyll c co-aggregated with β-carotene, which is used to extend the light-harvesting spectral range, and bacteriochlorophyll a, which acts as a final acceptor for excitation energy. Efficient energy transfer between all three components was observed by means of fluorescence spectroscopy. The efficiency varies with the β-carotene content, which increases the average distance between the donor and acceptor in both energy transfer steps. The efficiency ranges from 89 to 37% for the transfer from β-carotene to bacteriochlorophyll c, and from 93 to 69% for the bacteriochlorophyll c to bacteriochlorophyll a step. A significant part of this study was dedicated to a development of methods for determination of energy transfer efficiency. These methods may be applied also for study of chlorosomes and other pigment complexes.

Altered functional connectivity of brainstem nuclei in new daily persistent headache: Evidence from resting-state functional magnetic resonance imaging.

The new daily persistent headache (NDPH) is a rare primary headache disorder. However, the underlying mechanisms of NDPH remain incompletely understood. This study aims to apply seed-based analysis to explore the functional connectivity (FC) of brainstem nuclei in patients with NDPH using resting-state functional magnetic resonance imaging (MRI). The FC analysis from the region of interest (ROI) to whole brain voxels was used to investigate 29 patients with NDPH and 37 well-matched healthy controls (HCs) with 3.0 Tesla MRI. The 76 nuclei in the brainstem atlas were defined as ROIs. Furthermore, we explored the correlations between FC and patients' clinical characteristics and neuropsychological evaluations. Patients with NDPH exhibited reduced FC in multiple brainstem nuclei compared to HCs (including right inferior medullary reticular formation, right mesencephalic reticular formation, bilateral locus coeruleus, bilateral laterodorsal tegmental nucleus-central gray of the rhombencephalon, median raphe, left medial parabrachial nucleus, periaqueductal gray, and bilateral ventral tegmental area-parabrachial pigmented nucleus complex) and increased FC in periaqueductal gray. No significant correlations were found between the FC of these brain regions and clinical characteristics or neuropsychological evaluations after Bonferroni correction (p > 0.00016). Our results demonstrated that patients with NDPH have abnormal FC of brainstem nuclei involved in the perception and regulation of pain and emotions.

Role of autonomic, nociceptive, and limbic brainstem nuclei in core autism features.

Although multiple theories have speculated about the brainstem reticular formation's involvement in autistic behaviors, the in vivo imaging of brainstem nuclei needed to test these theories has proven technologically challenging. Using methods to improve brainstem imaging in children, this study set out to elucidate the role of the autonomic, nociceptive, and limbic brainstem nuclei in the autism features of 145 children (74 autistic children, 6.0-10.9 years). Participants completed an assessment of core autism features and diffusion- and T1-weighted imaging optimized to improve brainstem images. After data reduction via principal component analysis, correlational analyses examined associations among autism features and the microstructural properties of brainstem clusters. Independent replication was performed in 43 adolescents (24 autistic, 13.0-17.9 years). We found specific nuclei, most robustly the parvicellular reticular formation-alpha (PCRtA) and to a lesser degree the lateral parabrachial nucleus (LPB) and ventral tegmental parabrachial pigmented complex (VTA-PBP), to be associated with autism features. The PCRtA and some of the LPB associations were independently found in the replication sample, but the VTA-PBP associations were not. Consistent with theoretical perspectives, the findings suggest that individual differences in pontine reticular formation nuclei contribute to the prominence of autistic features. Specifically, the PCRtA, a nucleus involved in mastication, digestion, and cardio-respiration in animal models, was associated with social communication in children, while the LPB, a pain-network nucleus, was associated with repetitive behaviors. These findings highlight the contributions of key autonomic brainstem nuclei to the expression of core autism features.

Recent Advances in Photosynthesis, Plant Hormones and Applications in Plant Growth

Changes in the pigment and protein complexes involved in the light reactions of photosynthesis can be caused by environmental conditions, particularly those related to light quality and intensity during growth. The metabolome analysis of rice and soybean showed that dehydration stress increased the levels of galactinol and raffinose. One key method by which microorganisms control plant development has been proposed to be the generation of auxin or auxin precursors by bacteria associated with roots, or the manipulation of auxin production in plants. The effects of pathogenic and beneficial root-interacting fungi on the hormone content and auxin responsiveness of Arabidopsis, as determined by the auxin-inducible promoter system. Many developmental processes, like stem elongation, germination, vegetative growth, blooming, and reproduction, are regulated by GAs. Analyzing the metabolome of Several distinct defensive mechanisms function in different ways to prevent or lessen harm. Coeluting substances in the sample matrix have an effect on the analyte signals. They can impede or, less frequently, increase the analyte's ionization process, producing stronger or weaker signals, respectively. Furthermore, auxin, a different hormone present in plants, combines with cytokinins to prevent senescence, which, at least in its early stages, serves as a structured metabolic time and a tissue breakdown. Furthermore, synthetic amino acids with unique light-absorbing side chains may be used to add colors to such a new photosystem and rice showed that under circumstances of dehydration stress, levels of galactinol and raffinose were enhanced.

Leather bergenia as an alternative to synthetic colorants for food systems

The topicality of studying synthetic colorants and a possibility of their strictly regulated application is linked with an increasing producers’ interest in natural food colorants due to the attempt to grant the status of natural products to foods. New data on the content of photosynthetic pigments in leaves of leather bergenia (Вergenia crassifolia (L.) Fitsch) of different periods of vegetation growing in the Republic of Buryatia were obtained in this work. It is shown that it is one of the few plants, which leaves contain a significant amount of carotenoids. Their maximum total content (1257.9 ± 33.1 mmol/mol chlorophyll) was noticed in red leaves of bergenia. Seasonal changes in the complex of photosynthetic pigments in leaves were revealed. For example, the content of chlorophylls in black leaves reduced by four times compared to the amount of pigments in green leaves. Insignificant losses of the pool of green pigments were also observed in red leaves. About 18% of chlorophylls remained in black leaves. During the period after plants’ appearance from under the snow, the content of chlorophyll α increased by 3 times and chlorophyll β by 1.8 times. In leaves of bergenia, β- carotene was found in the composition of carotenoids (30% of the sum of carotenoids). Among xanthophyllic pigments, lutein was found in the prevailing quantity; its proportion accounted for 51% of the sum of carotenoids.

Differences in the Chromogenic Effect of Corn Starch and Potato Starch on Paprika Red Pigment and Structural Characterisation.

The present study aims to investigate the chromogenic effect and the interaction between starch-pigment complexes of corn starch (CS) and potato starch (PS) complexed with paprika red pigment. Compared to PS, CS showed 12.5 times higher adsorption capacity for paprika red pigment. Additionally, the a* value of CS-P (26.90 ± 0.23) was significantly higher than that of PS-P (22.45 ± 1.84), resulting in a corn starch-paprika red pigment complex (CS-P) with a more intense red colour. The addition of paprika red pigment significantly decreased the particle size and porosity of CS by 48.14 ± 5.29% and 17.01 ± 3.80%, respectively. Conversely, no significant impact on PS was observed. Additionally, the Fourier transform infrared (FT-IR) spectroscopy results revealed that the starch molecules and paprika red pigment were bound to each other through strong hydrogen bonds. X-diffraction (XRD) results indicated that the starch-paprika red pigment complexes have a V-shaped structure. Furthermore, the relative crystallinity of the complexes between starch and red pepper pigment showed an increasing trend, however, the relative crystallinity of CS increased significantly by 11.77 ± 0.99-49.21 ± 3.67%. Consequently, the CS-P colouring was good.

The influence of biological preparations on the condition of the pigment complex of the leaf apparatus of buckwheat

The influence of biological preparations on the condition of the pigment complex of the leaf apparatus of buckwheat

Strategy of Surgical Treatment of Patients with Pigment Dispersion Syndrome and Myopia

Purpose: to conduct a prospective study of the results of surgical treatment of patients with pigment dispersion syndrome and complex myopic astigmatism. Materials and methods. As a result of a comprehensive examination of 10453 adult primary patients with complex myopic astigmatism, the diagnosis of pigment dispersion syndrome was made in 99 patients (0.94 %). The study group consisted of 22 people, 9 men and 13 women, with an average age of 29.4 ± 9.8. In the case of iridosonular contact, according to ultrasound biomicroscopy, laser basal iridectomy was performed at the first stage. In the case of normal intraocular pressure indicators, laser correction of myopia was made in patients of the study group within 6 months after laser basal iridectomy. Results. During biomicroscopy, a Krukenberg spindle was observed in 34 eyes (77.2 %), exogenous pigment was detected in 20 eyes (45.4 %) on the iris and lens, and sectoral illumination of the iris was detected in 5 (11.4 %). After laser basal iridectomy on 24 eyes (54.5 %) in all the studied meridians, we noted a tendency to deepen the posterior chamber, but the increase was statistically significant only at 12 hours (P < 0.05). The achieved decrease in the angle of the anterior chamber was statistically significant (P < 0.05) in the meridians of 3, 9 and 12 hours and ranged from 3.56 to 8.53 degrees in different meridians. Laser correction of complex myopic astigmatism was performed in 11 patients (22 eyes) using ReLEx® SMILE technology and 10 (20 eyes) patients using FemtoLASIK technology. At the end of the observation period after correction, refraction within ±0.5 dptr of the planned one was achieved in 88.1 % of cases (37 eyes), ±1.0 dptr — in 100 % of cases. The efficiency coefficient was 88.46 %, the safety coefficient was 92.8 %. Postoperative values of corneal-compensated IOP were comparable with preoperative indicators (P > 0.05). Conclusions. The analysis of the of surgical treatment results in the patients with pigment dispersion syndrome and myopia showed the absence of negative dynamics in the course, as well as high efficiency, safety and stability of the results achieved after laser correction. The applied algorithm for the management of patients with combined pathology with pigment dispersion syndrome and myopia is pathogenetically justified, safe, promotes the preservation of visual functions of patients and improves their quality of life.