Primary Pigment Research Articles

Fine Structure of the Compound Eyes of Male and FemaleHeortia vitessoidesMoore (Lepidoptera: Crambidae)

AbstractHeortia vitessoides is a destructive pest of the economically important plant Aquilaria sinensis in China. We investigated the external morphology and ultrastructure of H. vitessoides compound eyes using scanning and transmission electron microscopy. We found that H. vitessoides has superposition eyes, made up of a mean of 3,671 and 3,428 ommatidia in males and females, respectively. The mean ommatidial diameter for males and females was 18.87 and 16.81 µm, respectively. Each ommatidium was capped by a convexly curved corneal facet lens of about 13.85 µm thickness. Corneal nipples measuring 226.36 nm in height in males and 295.48 nm in females, covered the surface of the eyes. Heortia vitessoides eyes are eucone, with each ommatidium having a crystalline cone comprising four cone cells, surrounded by two primary pigment cells. The centrally fused rhabdom of each ommatidium was formed by 8–11 of retinal cells, somewhat more than are typically found in Lepidoptera. The relatively large size of the compound eyes, the large number of ommatidia, large number of retinula cells, and high corneal nipples all suggest that H. vitessoides eyes are adapted to optimize visual sensitivity under dim light conditions.

The effect of xylotrophic basidiomycetes on the photosynthetic pigments of small-leaved trees

Xylotrophic basidiomycetes are an essential component of any biogeocoenosis. It is due to these organisms that one of the most important processes occurs throughout the biosphere, namely the decomposition of organic substances and, first of all, cellulose, which is synthesized by producers. However, these phytopathogens bring significant losses to forestry, making wood unsuitable for industrial use. At the same time, sufficiently effective methods for diagnosing and assessing wood damage by heartwood rot, which are caused by xylotrophic basidiomycetes, have not been developed. The paper studies the peculiarity of the influence of these phytopathogens on the pigment apparatus of valuable small-leaved tree species using the methods of spectroscopy and electrophotocolorimetry, while comparing the rate of degradation of the main pigments of photosynthesis chlorophylls a and b to pheophytin, as well as assesses the content of chlorophyll, and auxiliary pigments such as carotenoids and xanthophylls in healthy trees and trees with signs of damage by pathogenic xylotrophs. A significant number of effects of phytopathogens on leaf pigment apparatus of small-leaved tree species have been identified. Among those are rapid degradation of primary and secondary pigments, distortion of chlorophyll a concentration data caused by filter properties of photoelectric colorimeter and higher chlorophyll b concentration in affected trees in comparison to control sample. These methods and the results obtained can be actively used both in forestry to assess the phytosanitary state of small-leaved trees, and to further study the features of the interaction of xylotrophic basidiomycetes with woody plants.

The mechanisms of color production in black skin versus red skin on the heads of New World vultures

A determination of how the color of animal integument is produced is a starting point for investigations into the function and evolution of coloration. The mechanisms that give rise to the color of bare skin of New World vultures are largely unexplored. Here, we investigate the source of color production in the bare skin of Turkey Vultures (Cathartes aura) and Black Vultures (Coragyps atratus). Using UV–vis reflectance spectroscopy, we found evidence that hemoglobin is the primary pigment responsible for the red coloration of the bare skin on the heads of Turkey Vultures, and that eumelanin is responsible for the black coloration of the bare skin on the heads of Black Vultures. Light microscopy of incisional skin samples further supported these mechanisms of color production by revealing the presence of numerous blood vessels near the surface of the Turkey Vulture skin, and a high concentration of melanosomes in the skin of Black Vultures. Using high performance liquid chromatography (HPLC), we detected carotenoids within the skin of both species with significantly higher total concentrations of carotenoids in the skin of Turkey Vultures compared to the skin of Black Vultures. The carotenoids detected were dietary carotenoids that typically produce yellow coloration when accumulated in integument and were present in low concentrations. We hypothesize that the dietary carotenoids present do not contribute to the color of the skin, but rather help to compensate for the lack of melanosomes found in Turkey Vulture skin. The presence of additional carotenoids may act as an antioxidant to minimize UV damage when the bare Turkey Vulture head skin is exposed to direct sunlight for prolonged periods of time when soaring and scavenging for food.

MiR-302d inhibits TGFB-induced EMT and promotes MET in primary human RPE cells.

Transforming growth factor-beta (TGFB)-mediated epithelial-mesenchymal transition (EMT) plays a crucial role in the pathogenesis of retinal fibrosis, which is one of the leading causes of impaired vision. Current approaches to treating retinal fibrosis focus, among other things, on inhibiting the TGFB signaling pathway. Transient expression of microRNAs (miRNAs) is one way to inhibit the TGFB pathway post-transcriptionally. Our previous study identified the miRNA miR-302d as a regulator of multiple TGFB-related genes in ARPE-19 cells. To further explore its effect on primary cells, the effect of miR-302d on TGFB-induced EMT in primary human retinal pigment epithelium (hRPE) was investigated in vitro. hRPE cells were extracted from patients receiving enucleation. Transfection of hRPE cells with miR-302d was performed before or after TGFB1 stimulation. Live-cell imaging, immunocytochemistry staining, Western blot, and ELISA assays were utilized to identify the alterations of cellular morphology and EMT-related factors expressions in hRPE cells. hRPE cells underwent EMT by TGFB1 exposure. The transfection of miR-302d inhibited the transition with decreased production of mesenchymal markers and increased epithelial factors. Meanwhile, the phosphorylation of SMAD2 activated by TGFB1 was suppressed. Moreover, miR-302d expression promoted TGFB1-induced fibroblast-like hRPE cells to revert towards an epithelial stage. As confirmed by ELISA, miR-302d reduced TGFB receptor 2 (TGFBR2) and vascular endothelial growth factor A (VEGFA) levels 48 hours after transfection. The protective effect of miR-302d might be a promising approach for ameliorating retinal fibrosis and neovascularization. MiR-302d suppresses TGFB-induced EMT in hRPE cells via downregulation of TGFBR2, even reversing the process. Furthermore, miR-302d reduces the constitutive secretion of VEGFA from hRPE cells.

Identification of crucial genes and metabolites regulating the eggshell brownness in chicken

BackgroundProtoporphyrin IX (Pp IX) is the primary pigment for brown eggshells. However, the regulatory mechanisms directing Pp IX synthesis, transport, and genetic regulation during eggshell calcification in chickens remain obscure. In this study, we investigated the mechanism of brown eggshell formation at different times following oviposition, using White Leghorn hens (WS group), Rhode Island Red light brown eggshell line hens (LBS group) and Rhode Island Red dark brown eggshell line hens (DBS group).ResultsAt 4, 16 and 22 h following oviposition, Pp IX concentrations in LBS and DBS groups were significantly higher in shell glands than in liver (P < 0.05). Pp IX concentrations in shell glands of LBS and DBS groups at 16 and 22 h following oviposition were significantly higher than WS group (P < 0.05). In comparative transcriptome analysis, δ-aminolevulinate synthase 1 (ALAS1), solute carrier family 25 member 38 (SLC25A38), ATP binding cassette subfamily G member 2 (ABCG2) and feline leukemia virus subgroup C cellular receptor 1 (FLVCR1), which were associated with Pp IX synthesis, were identified as differentially expressed genes (DEGs). RT-qPCR results showed that the expression level of ALAS1 in shell glands was significantly higher in DBS group than in WS group at 16 and 22 h following oviposition (P < 0.05). In addition, four single nucleotide polymorphisms (SNPs) in ALAS1 gene that were significantly associated with eggshell brownness were identified. By identifying the differential metabolites in LBS and DBS groups, we found 11-hydroxy-E4-neuroprostane in shell glands and 15-dehydro-prostaglandin E1(1-) and prostaglandin G2 2-glyceryl ester in uterine fluid were related to eggshell pigment secretion.ConclusionsIn this study, the regulatory mechanisms of eggshell brownness were studied comprehensively by different eggshell color and time following oviposition. Results show that Pp IX is synthesized de novo and stored in shell gland, and ALAS1 is a key gene regulating Pp IX synthesis in the shell gland. We found three transporters in Pp IX pathway and three metabolites in shell glands and uterine fluid that may influence eggshell browning.

A study on histopathological and dermoscopic correlations in pityriasis versicolor

Pityriasis versicolor (PV) is a superficial mycoses caused by a lipophilic fungus; Malassezia yeast. Dermoscopy can be used as a complementary tool for assessing PV, but histopathology is confirmatory, whenever results of KOH (potassium hydroxide) examination are inconclusive. There is dearth of Indian data on the findings of dermoscopy and histopathology of PV. To find the correlation between dermoscopic and histopathological features in Pityriasis versicolor. Fifty consecutive patients diagnosed with PV were recruited in the cross sectional study. KOH mount of the skin scrapings from the lesions was done on the patients and were positive in all the patients. Dermoscopy was done in all the patients using ILLUCO Dermoscope and features were noted. Biopsy was sent for histopathological examination. Hypopigmented variant was the most common type (62%) in the patients. Dermoscopic analysis showed altered pigmentary network as the most common finding in almost all the patients, followed by scaling which was present in 21 patients. Folliculocentric pattern was seen in 20% of the patients. A peculiar finding contrast halo ring around the primary altered pigmentation was observed in 4 patients. Invasion of hair follicle by yeast was noticed in 18% patients. The most common histopathological change seen was perivascular infiltrate (78%) followed by hyperkeratosis (62%). There was presence of hyphae spores in 40% of the patients. 42% of the patients had spongiosis in their histopathological pattern. Special stain was done in 20 patients. Dermoscopy with features such as altered pigmentary network, contrast halo sign and yeast invasion of hair follicles when complemented with the histopathological features like perivascular infiltrate, hyperkeratosis, hyphae spores and spongiosis help in diagnosing PV.

Electron microscopic investigation of benzo(a)pyrene-induced alterations in the rat kidney tissue and the protective effects of curcumin

ABSTRACT Benzo(a)pyrene (BaP) is a polycyclic hydrocarbon with carcinogenic and DNA damaging properties. Curcumin, primary yellow pigment in turmeric, has a wide range of biological, pharmacological properties in addition to being a powerful antioxidant. The aim of this study was to investigate protective effects of curcumin against benzo(a)pyrene damage in rat kidney. Thirty-six male Wistar albino rats were divided into six groups (n = 6) as: control, corn oil, Dimethyl sulfoxide (DMSO), BaP (10 mg/kg/day), Curcumin (100 mg/kg/day), Curcumin+BaP (100 mg/kg/day+10 mg/kg/day). Agents were daily and orally administered for six weeks. Kidney tissues were removed and examined ultrastructurally. Glomerular and tubular structures in control, corn oil, and DMSO groups demonstrated normal features. Glomerular capillary dilation, thickening, and folding of basement membrane and disruption of organelle contents were distinguished in BaP group. Deletion of podocyte cell and pedicels also sponge-like appearance of glomerular surface were remarkable in this group. Tissue components were protected in curcumin treated group. Proximal tubules and glomerular basement membrane exhibited normal features in Curcumin+BaP group. The abnormalities that accompanied BaP administration clearly revealed the detrimental effects of this agent. Therefore, this study provided substantial evidence that curcumin protects against benzo(a)pyrene nephrotoxicity.

Identification and Functional Analysis of the Promoter of a Leucoanthocyanidin Reductase Gene from Gossypium hirsutum.

Leucoanthocyanidin reductase (LAR) is the critical enzyme in the synthesis pathway of proanthocyanidins, which are the primary pigments in brown cotton fibers. Our previous study has revealed significant differences in the expression levels of GhLAR1 between white and brown cotton fibers at 10 DPA. In this work, the expression pattern of the GhLAR1 gene was further studied, and the promoter of GhLAR1 (1780bp) was isolated and characterized. Bioinformatic analysis indicated that GhLAR1 promoter contained many known light response elements and several defenses related to transcriptional factor-binding boxes, which may partially explain the response of the GhLAR1 to temperature, NaCl, and PEG treatments. Furthermore, GhLAR1 was preferentially and strongly expressed in fibers and flowers of cotton, and the expression levels in all tested tissues (especially fibers) of brown cotton were significantly higher than those in white cotton. Consistent with the expression analysis, the GhLAR1 promoter mainly drove GUS expression in epidermal trichomes and floral organs.

Protective effects of curcumin on ischemia/reperfusion injury.

Ischemia/reperfusion (I/R) injury is a term used to describe phenomena connected to the dysfunction of various tissue damage due to reperfusion after ischemic injury. While I/R may result in systemic inflammatory response syndrome or multiple organ dysfunction syndrome, there is still a long way to improve therapeutic outcomes. A number of cellular metabolic and ultrastructural alterations occur by prolonged ischemia. Ischemia increases the expression of proinflammatory gene products and bioactive substances within the endothelium, such as cytokines, leukocytes, and adhesion molecules, even as suppressing the expression of other "protective" gene products and substances, such as thrombomodulin and constitutive nitric oxide synthase (e.g., prostacyclin, nitric oxide [NO]). Curcumin is the primary phenolic pigment derived from turmeric, the powdered rhizome of Curcuma longa. Numerous studies have shown that curcumin has strong antiinflammatory and antioxidant characteristics. It also prevents lipid peroxidation and scavenges free radicals like superoxide anion, singlet oxygen, NO, and hydroxyl. In our study, we highlight the mechanisms of protective effects of curcumin against I/R injury in various organs.

Transcriptional comparison of adult human primary Retinal Pigment Epithelium, human pluripotent stem cell-derived Retinal Pigment Epithelium, and ARPE19 cells.

The therapeutic potential of pluripotent stem cells is great as they promise to usher in a new era of medicine where cells or organs may be prescribed to replace dysfunctional tissue. At the forefront are efforts in the eye to develop this technology as it lends itself to in vivo monitoring and sophisticated non-invasive imaging modalities. In the retina, retinal pigment epithelium (RPE) is the most promising replacement cell as it has a single layer, is relatively simple to transplant, and is associated with several eye diseases. However, after transplantation, the cells may transform and cause complications. This transformation may be partially due to incomplete maturation. With the goal of learning how to mature RPE, we compared induced pluripotent stem cell-derived RPE (iPSC-RPE) cells with adult human primary RPE (ahRPE) cells and the immortalized human ARPE-19 line. We cultured ARPE-19, iPSC-RPE, and ahRPE cells for one month, and evaluated morphology, RPE marker staining, and transepithelial electrical resistance (TEER) as quality control indicators. We then isolated RNA for bulk RNA-sequencing and DNA for genotyping. We genotyped ahRPE lines for the top age-related macular degeneration (AMD) and proliferative vitreoretinopathy (PVR) risk allele polymorphisms. Transcriptome data verified that both adult and iPSC-RPE exhibit similar RPE gene expression signatures, significantly higher than ARPE-19. In addition, in iPSC-RPE, genes relating to stem cell maintenance, retina development, and muscle contraction were significantly upregulated compared to ahRPE. We compared ahRPE to iPSC-RPE in a model of epithelial-mesenchymal transition (EMT) and observed an increased sensitivity of iPSC-RPE to producing contractile aggregates in vitro which resembles incident reports upon transplantation. P38 inhibition was capable of inhibiting iPSC-RPE–derived aggregates. In summary, we find that the transcriptomic signature of iPSC-RPE conveys an immature RPE state which may be ameliorated by targeting “immature” gene regulatory networks.

Primary Composition and Pigments of 11 Red Seaweed Species from the Center of Portugal

Macroalgae have been regarded as a natural food source since ancient times, their nutritional value being not only proven by recent studies, but also triggering further in-depth research efforts on the matter. The present study aims to provide an insight into the nutritional potential of selected red seaweed species collected in central Portugal by specifically comparing the moist yield and ash content, crude protein, total lipids, carbohydrates and pigment content between species and, ultimately, finding out if there are differences between taxa. The results obtained highlighted the most nutritionally appealing species, namely, Plocamium cartilagineum with respect to protein content (23.18% dw) and Sphaerocococcus coronopifolius with respect to carbohydrate content (40.23% dw), while none of the species studied showed a lipid content higher than 1.80% dw. Regarding pigment content, the highest concentrations of phycoerythrin, carotenoid and chlorophyll a were obtained, respectively, from P. cartilagineum (0.09 mg.mL−1), Porphyra umbilicalis (1.88 µg.g−1 fw) and Jania rubens (38.41 µg.mL−1). We concluded that there are significant differences between the species studied regarding their nutritional profile, with a marked difference between Corallinales and all other species not belonging to this order; regarding pigment content, this variation between orders was not observed. Nevertheless, all the studied species may act as promising complements in a human healthy diet.

Properties of Cephalopod Skin Ommochromes to Inhibit Free Radicals, and the Maillard Reaction and Retino-Protective Mechanisms in Cellular Models Concerning Oxidative Stress, Angiogenesis, and Inflammation

Ommochromes are pigments of invertebrates that exhibit oxidative stress protection. The aim of this study was to investigate ommochromes extracted from cephalopod’s skin for their ability to inhibit age-related-macular degeneration (AMD)-related factors such as H2O2-induced and iron-dependent oxidative stress (ferroptosis and erastin), accumulation of advanced glycation end-products (AGEs), as well as vascular endothelial growth factor (VEGF), and inflammatory cytokines (interleukin 6 and interleukin 8) secretion. As cell systems, we used primary porcine retinal pigment epithelium (RPE), human retinal pigment epithelium cell line ARPE-19 and uveal melanoma cell line OMM-1. In vitro, ommochromes produced an antiglycation effect by the inhibition of fructosylation reaction. The ommochromes showed protective effects against erastin- induced cell death in ARPE-19. In addition, in long-term stimulation (7 days) ommochromes decreased constitutively secreted VEGF, as well as interleukin 6 and interleukin 8 induced by Poly I:C in primary RPE. No relevant effects were detected in OMM-1 cells. The effects are dependent on the cell system, time of exposition, and concentration. This substance is of interest for further research concerning age-related macular degeneration.

Red wine coloration: A review of pigmented molecules, reactions, and applications.

Color is one of the most distinctive qualities of red wine. Despite new knowledge in the field of pigment identification, copigmentation, and oxidation being forthcoming, there is still a large gap between the fundamental research and practical winemaking outcomes. A state-of-art review from these two aspects is, therefore, necessary. This review first introduces updated knowledge about the primary pigments in wine, with emphasis on their physicochemical properties. Then, the mechanisms of copigmentation and oxidation are elucidated in detail, along with their relative contributions to wine color. Finally, the practical effects of copigmentation and micro-oxygenation (MOX) in winemaking are summarized and discussed. In general, wine coloration is ultimately determined by the anthocyanin flavylium cation, which is greatly influenced by wine pH. In young red wine, grape-derived anthocyanins and nonanthocyanin polyphenols (as copigments) are the foundation for wine coloration. During aging and storage, anthocyanin derivatives are formed via various chemical reactions, where moderate oxidation plays a vital role, whereas copigmentation constantly decreases. The essence of wine color evolution relates to the changes of physicochemical properties of primary pigments in wine, where the hydration equilibrium gradually diminishes. In practice, the effects of copigment addition and MOX during real vinification can be viewed as somewhat controversial, considering that many studies showed different effects on wine color and pigment concentration. Universal features can be summarized but some phenomena still remain unclear and deserve further exploration.

The mounted alloimmunity of the iris-ciliary body devotes a hotbed of immune cells for corneal transplantation rejection

Graft rejection is still the major obstacle causing corneal transplantation failure. However, the underlying pathogenesis remains largely unclear. The iris-ciliary body (I–C) is enriched with blood vessels and various immune cell populations, presumably predisposed to be involved in corneal transplantation rejection. After penetrating keratoplasty, compared to the normal (Nor) and syngeneic (Syn) groups, I–C tissues in the allogeneic (Allo) group displayed stronger alloimmune responses, with more infiltrations of CD45+ inflammatory cells and CD3+ lymphocytes, increased transcriptional levels of pro-inflammatory cytokines, and elevated NF-κB activity. This histopathology was similar to the pathological alterations of corneal allografts. Angiography analysis revealed the abnormal vasculature in the iris during allograft rejection, characterized by vasodilatation, increased vessel density, and vascular permeability. While, immunofluorescence staining showed the intact tight junction of the posterior iris epithelium. In vitro, human microvascular endothelial cells (HMECs) stimulated by tumor necrosis factor-α (TNF-α) showed an increased Evans blue (EB)-albumin leakage, with lower expression of zonula occludens-1 (ZO-1) and Occludin. The increased EB-albumin leakage, up-regulated NF-κB activity, and reduced expression of ZO-1 and Occludin could be partially reversed after cyclosporine A (CsA) administration. In contrast, the barrier function in primary mouse iris pigment epithelial cells (IPEs) after TNF-α treatment remained largely unchanged. These findings revealed the vigorous alloimmunity in I–C tissues, characterized with impaired vascularization but intact posterior epithelial barrier in the iris, which allowed proteins and immune cells to be exudated from the front surface of I–C tissues, and facilitated immune reaction in the anterior chamber, thereby contributing to aggravated corneal transplantation rejection.

Utilization of anaerobically digested dairy manure wastewater for Spirulina maxima cultivation

Microalgae have attracted the attention of scientists as microalgae have been considered as having higher productivities than terrestrial plants. Microalgae can be used to produce several valuable commodities such as bioenergy, feed, and food. Combining the growth medium with wastewater can enhance the economic feasibility of microalgae-based products. In this research, Spirulina maxima were cultivated using bioslurry from anaerobically digested dairy manure wastewater (ADDMW) at concentrations 0, 50, and 100 %. The growth curve was monitored by measuring the dry weight of microalgae every three days. The results showed that the S. maxima growth in ADDMW showed no difference from S. maxima growth in Zarrouk medium (2.090 g L-1 and 1.933 g L-1, respectively). Phycocyanin, one of the primary pigments of S. maxima, was determined to evaluate the effect of wastewater medium on phycocyanin production. The phycocyanin content of S. maxima in 0, 50, and 100 % wastewater showed no difference (58.67, 56.51, and 54.67 mg L-1 culture, respectively). This study provides an insight into the potential use of ADDMW as a substitute of growth medium of S. maxima as it supported the growth and phycocyanin production, with the result similar to when using the commercial medium.

Diversity and Metabolic Activity of Fungi Causing Biodeterioration of Canvas Paintings.

Research into the biodeteriorative potential of fungi can serve as an indicator of the condition of heritage items. Biodeterioration of canvas paintings as a result of fungal metabolic activity is understudied with respect to both the species diversity and mechanisms involved. This study brings new evidence for the physiology of fungi biodeteriorative capacity of canvas paintings. Twenty-one fungal isolates were recovered from four oil paintings (The Art Museum, Cluj-Napoca) and one gouache painting (private collection), dating from the 18th to 20th centuries. The species, identified based on the molecular markers Internal Transcribed Spacer (ITS), beta-tubulin (tub2), or translation elongation factor 1 (TEF-1), are common colonisers of canvas paintings or indoor environments (e.g., Penicillium spp., Aspergillus spp., Alternaria spp.). Fungi enzymatic profiles were investigated by means of hydrolysable substrates, included in culture media or in test strips, containing components commonly used in canvas paintings. The pigment solubilisation capacity was assessed in culture media for the primary pigments and studied in relation to the organic acid secretion. Caseinases, amylases, gelatinases, acid phosphatase, N-acetyl-β-glucosaminidase, naphthol-AS-BI-phosphohydrolase, and β-glucosidase were found to be the enzymes most likely involved in the processes of substrate colonisation and breakdown of its components. Aureobasidium genus was found to hold the strongest biodeteriorative potential, followed by Cladosporium, Penicillium, Trichoderma, and Aspergillus. Blue pigment solubilisation was detected, occurring as a result of organic acids secretion. Distinct clusters were delineated considering the metabolic activities detected, indicating that fungi specialise in utilisation of certain types of substrates. It was found that both aged and modern artworks are at risk of fungal biodeterioration, due to the enzymatic activities’ diversity and intensity, pigment solubilisation capacity or pigment secretion.

Identification of significant residues for intermediate accumulation in phycocyanobilin synthesis.

Phycocyanobilin, the primary pigment of both light perception and light-harvesting in cyanobacteria, is synthesized from biliverdin IXα (BV) through intermediate 181, 182-dihydrobiliverdin (181, 182-DHBV) by a phycocyanobilin:ferredoxin oxidoreductase (PcyA). In our previous study, we discovered two PcyA homologs (AmPcyAc and AmPcyAp) derived from Acaryochloris marina MBIC 11017 (A. marina) that exceptionally uses chlorophyll d as the primary photosynthetic pigment, absorbing longer wavelength far-red light than chlorophyll a, the photosynthetic pigment found in most cyanobacteria. Biochemical characterization of the two PcyA homologs identified functional diversification of these two enzymes: AmPcyAc provides 181, 182-DHBV, and PCB to the cyanobacteriochrome (CBCR) photoreceptors, whereas, AmPcyAp specifically provides PCB to the light-harvesting phycobilisome subunit. In this study, we focused on the residues necessary for 181, 182-DHBV supply to the CBCR photoreceptors by AmPcyAc. Based on the SyPcyA structure, we concentrated on the 30 residues that constitute the substrate-binding pocket. Among them, we discovered that Leu151 and Val225 in AmPcyAc were both substituted with isoleucine. During the enzymatic reaction, the SyPcyA variant molecule, possessing V225I and L151I replacements, accumulates the 181, 182-DHBV and supplies it to a CBCR molecule derived from A. marina. It is worth noting that the substitution of Val225 with isoleucine was specifically conserved among the Acaryochloris genus. Collectively, we propose that the specific evolution of PcyA among the Acaryochloris genus may correlate with the acquisition of Chl. d synthetic ability and growth in long-wavelength far-red light environments.

Quantification of mitophagy using mKeima-mito in cultured human primary retinal pigment epithelial cells

The retinal pigment epithelium is a pigmented monolayer of cells that help maintain a healthy retina. Loss of this essential cell layer is implicated in a number of visual disorders, including age-related macular degeneration (AMD). Utilizing primary RPE cultures to investigate disease is an important step in understanding disease mechanisms. However, the use of primary RPE cultures presents a number of challenges, including the limited number of cells available and the presence of auto-fluorescent pigment that interferes with quantifying fluorescent probes. Additionally, primary RPE are difficult to transfect with exogenous nucleic acids traditionally used for fluorescent imaging. To overcome these challenges, we used an adeno-associated viral (AAV) vector to express a pH sensitive fluorescent protein, mKeima, fused to the mitochondrial targeting sequence of cytochrome oxidase subunit 8A (mKeima-mito). mKeima-mito allows for quantification of mitochondrial autophagy (mitophagy) in live-cell time-lapse imaging experiments. We also developed an image analysis pipeline to selectively quantify mKeima-mito while removing the signal of auto-fluorescent pigment from the dataset by utilizing information from the mKeima fluorescent channels. These techniques are demonstrated in primary RPE cultures expressing mKeima-mito treated with 2-[2-[4-(trifluoromethoxy)phenyl]hydrazinylidene]-propanedinitrile (FCCP), an uncoupler that depolarizes the mitochondrial membrane and leads to mitochondrial fragmentation and mitophagy. The techniques outlined provide a roadmap for investigating disease mechanisms or the effect of treatments utilizing fluorescent probes in an important cell culture model.

Photoacclimation and Light Thresholds for Cold Temperate Seagrasses.

Water quality deterioration is expected to worsen the light conditions in shallow coastal waters with increasing human activities. Temperate seagrasses are known to tolerate a highly fluctuating light environment. However, depending on their ability to adjust to some decline in light conditions, decreases in daily light quantity and quality could affect seagrass physiology, productivity, and, eventually, survival if the Minimum Quantum Requirements (MQR) are not reached. To better understand if, how, and to what extent photosynthetic adjustments contribute to light acclimation, eelgrass (Zostera marina L.) shoots from the cold temperate St. Lawrence marine estuary (Rimouski, QC, Canada) were exposed to seven light intensity treatments (6, 36, 74, 133, 355, 503, and 860 μmol photons m–2 s–1, 14:10 light:dark photoperiod). Photosynthetic capacity and efficiency were quantified after five and 25 days of light exposure by Pulse Amplitude Modulated (PAM) fluorometry to assess the rapid response of the photosynthetic apparatus and its acclimation potential. Photoacclimation was also studied through physiological responses of leaves and shoots (gross and net primary production, pigment content, and light absorption). Shoots showed proof of photosynthetic adjustments at irradiances below 200 μmol photons m–2 s–1, which was identified as the threshold between limiting and saturating irradiances. Rapid Light Curves (RLC) and net primary production (NPP) rates revealed sustained maximal photosynthetic rates from the highest light treatments down to 74 μmol photons m–2 s–1, while a compensation point (NPP = 0) of 13.7 μmol photons m–2 s–1 was identified. In addition, an important package effect was observed, since an almost three-fold increase in chlorophyll content in the lowest compared to the highest light treatment did not change the leaves’ light absorption. These results shed new light on photosynthetic and physiological processes, triggering light acclimation in cold temperate eelgrass. Our study documents an MQR value for eelgrass in the St. Lawrence estuary, which is highly pertinent in the context of conservation and restoration of eelgrass meadows.

Fine Structure of the Visual System of Arge similis (Hymenoptera, Argidae).

Simple SummaryArge similis is a notorious pest on rhododendron plants. The fine structure of the compound eyes of A. similis adults were examined by light, scanning, and transmission electron microscopy. Each ommatidium consists of a lamellated cornea, a crystalline cone with eucone type, and a centrally fused rhabdom composed of eight retinular cells.External morphology and ultrastructure of the visual system of Arge similis (Vollenhoven, 1860) adults were investigated by light microscopy, scanning electron microscopy, and transmission electron microscopy. Each compound eye contains 2022 ± 89 (mean ± SE) facets in males and 2223 ± 52 facets in females. Arge similis has an apposition kind of compound eye composed of a cornea, a crystalline cone of four cone cells, and a centrally fused rhabdom made up of the rhabdomeres of eight large retinular cells. Each crystalline cone is surrounded by primary and secondary pigment cells with black spherical screening pigment granules measuring 0.60 ± 0.02 and 0.41 ± 0.01 μm in diameter, respectively. Based on our findings, the compound eye of A. similis can be expected to exhibit high adaptability to light intensity changes.