Redox State Research Articles

Lycopene alleviates chemotherapy-induced mucositis via enhancing intestinal barrier function and attenuating TLR4/MyD88/NF-κB signaling cascade

5-Fluorouracil (5-FU) is one of the most common chemotherapeutic agents used in treating solid tumors. Lycopene is a natural exogenous carotenoid with antioxidant, anti-inflammatory, immunomodulatory, and anticancer activity. Intestinal mucositis is a commonly encountered complication for chemotherapy. However, effective or preventive treatment for this common complication is still need to be elucidated. The current study aimed to appraise the effect of lycopene on 5-FU-induced intestinal mucositis (FUIIM). Twenty-eight male rats were divided randomly and equally into four groups: control, lycopene, FUIIM, and 5-FU + lycopene groups. Parameters for mucosal barrier integrity, redox and inflammatory status, and apoptosis were immunoassayed in addition to histological assessment. Decreased body weight, significantly impaired redox status, increased caspase 3 level, toll-like receptor (TLR) 4 level, myd88 and NF-κB expression. However, decreased Bcl-2, and Ki-67 expression were detected in 5-FUIIM group. Furthermore, impairment in intestinal barrier integrity, represented by decreased Occludin and claudin1 levels with impaired histological features and ultrastructural features, were also detected. Meanwhile, lycopene co-administration protected against weight loss, heightened oxidative stress, apoptosis, inflammation, disturbed intestinal barrier integrity, and impaired histological and ultrastructure features. In conclusion, lycopene significantly improved intestinal mucositis, barrier integrity and gut toxicity induced by 5-FU in rats.

Towards Designer Photocatalysts: Structure‐Property Relationships in 2,6‐Diaryl‐pyryliums

Fully organic photocatalyst systems are highly attractive, not merely because they are transition‐metal free, but more importantly due to their unique and often potent reactivity. A detailed understanding of the various redox states, both ground and excited state, and specifically what structural parameters control them is therefore crucial for harnessing the full potential of these systems in organic synthesis. However, unlike their organometallic counterparts, detailed structure‐property relationships for organic photocatalysts are largely absent from the literature. In this study, we demonstrate linear free‐energy relationships across a range of key photophysical and electrochemical properties of 2,6‐diarylpyryliums. Electronic absorption and emission maxima can be carefully tuned over the ranges of 83 nm and 102 nm respectively. Intramolecular charge transfer (ICT) interactions were revealed in cases of substitution with polarizable heavy‐atoms. A strong linear dependence of ground state reduction potentials on substituent electronics was observed. Notably, the excited state reduction potential, E*red, could be controlled over a range of nearly 1000 mV. Systematic errors in computational modeling of ground and excited state redox potentials were identified and corrected. We believe the quantitative structure‐property relationships identified here provide foundational tools for rational and predictive organic photocatalyst design.

Characterization of Groundwater Geochemistry in an Esker Aquifer in Western Finland Based on Three Years of Monitoring Data

This study investigated the hydrogeochemistry of a shallow Quaternary sedimentary aquifer in an esker deposition in western Finland, where distinct spatial and temporal variability in groundwater hydrogeochemistry has been observed. Field investigation and hydrogeochemical data were obtained from autumn 2010 to autumn 2013. The data were analyzed using the multivariate statistical methods principal component analysis (PCA) and hierarchical cluster analysis (HCA), in conjunction with groundwater classification based on the main ionic composition. The stable isotope ratios of δ18O and δD were used to determine the origin of the groundwater and its connection to surface water bodies. The groundwater geochemistry is characterized by distinct redox zones caused by the influence of organic matter, pyrite oxidation, and preferential flow pathways due to different hydrogeological conditions. The groundwater is of the Ca-HCO3 type and locally of the Ca-HCO3-SO4 type, with low TDS, alkalinity, and pH, but elevated Fe and Mn concentrations, KMnO4 consumption, and, occasionally, Ni concentrations. The decomposition of organic matter adds CO2 to the groundwater, and in this study, the dissolution of CO2 was found to increase the pH and enhance the buffering capacity of the groundwater. The mobility of redox-sensitive elements and trace metals is controlled by pH and redox conditions, which are affected by the pumping rate, precipitation, and temperature. With the expected future increases in precipitation and temperature, the buffering capacity of the aquifer system will enhance the balance between alkalinity from bioactivity and acidity from recharge and pyrite oxidation.

A redox-related lncRNA signature in bladder cancer.

The redox status is intricately linked to the development and progression of cancer, a process that can be modulated by long non-coding RNAs (lncRNAs). Previous studies have demonstrated that redox regulation can be considered a potential therapeutic approach for cancer. However, the redox-related lncRNA predictive signature specific to bladder cancer (BCa) has yet to be fully elucidated. The purpose of our study is to establish a redox-related lncRNA signature to improve the prognostic prediction for BCa patients. To achieve this, we downloaded transcriptome and clinical data from the Cancer Genome Atlas (TCGA) database. Prognostic redox-related lncRNAs were identified through univariate Cox regression, least absolute shrinkage and selection operator (LASSO) regression, and multivariate Cox regression analysis, resulting in the establishment of two risk groups. A comprehensive analysis corresponding to clinical features between high-risk and low-risk groups was conducted. Eight redox-related lncRNAs (AC018653.3, AC090229.1, AL357033.4, AL662844.4, AP003352.1, LINC00649, LINC01138, and MAFG-DT) were selected to construct the risk model. The overall survival (OS) in the high-risk group was worse than that in the low-risk group (p < 0.001). The redox-related lncRNA signature exhibits superior predictive accuracy compared to traditional clinicopathological characteristics. Gene Set Enrichment Analysis (GSEA) showed that the MAPK signaling pathway and Wnt signaling pathway were enriched in the high-risk group. Compared with the low-risk group, patients in the high-risk group demonstrated increased sensitivity to cisplatin, docetaxel, and paclitaxel. Furthermore, IGF2BP2, a potential target gene of MAFG-DT, was found to be overexpressed in tumor tissues and correlated with overall survival (OS). Our study demonstrated that the predictive signature based on eight redox-related lncRNAs can independently and accurately predict the prognosis of BCa patients.

α-Tocopherol Long-Chain Metabolite α-T-13'-COOH Exhibits Biphasic Effects on Cell Viability, Induces ROS-Dependent DNA Damage, and Modulates Redox Status in Murine RAW264.7 Macrophages.

The α-tocopherol long-chain metabolite α-tocopherol-13'-hydroxy-chromanol (α-T-13'-COOH) is a proposed regulatory intermediate of endogenous vitamin E metabolism. Effects of α-T-13'-COOH on cell viability and adaptive stress response are not well understood. The present study aims to investigate the concentration-dependent effects of α-T-13'-COOH on cellular redox homeostasis, genotoxicity, and cytotoxicity in murine RAW264.7 macrophages as a model system. Murine RAW264.7 macrophages are exposed to various dosages of α-T-13'-COOH to determine its regulatory effects on reactive oxygen species (ROS) production, DNA damage, expression of stress-related markers, and the activity of ROS scavenging enzymes including superoxide dismutases, catalase, and glutathione-S-transferases. The impact on cell viability is assessed by analyzing cell proliferation, cell cycle arrest, and cell apoptosis. α-T-13'-COOH influences ROS production and induces DNA damage in a dose-dependent manner. The metabolite modulates the activity of ROS-scavenging enzymes, with significant changes observed in the activities of antioxidant enzymes. A biphasic response affecting cell viability is noted: sub-micromolar doses of α-T-13'-COOH promote cell proliferation and enhance DNA synthesis, whereas supraphysiological doses lead to DNA damage and cytotoxicity. It hypothesizes an adaptive stress response, characterized by upregulation of ROS detoxification mechanisms, enhanced cell cycle arrest, and increased apoptosis, indicating a correlation with oxidative stress and subsequent cellular damage.

Human Supplementation with AM3, Spermidine, and Hesperidin Enhances Immune Function, Decreases Biological Age, and Improves Oxidative–Inflammatory State: A Randomized Controlled Trial

The positive effect of AM3, spermidine, and hesperidin, which have antioxidant and anti-inflammatory properties, on immunity is known, but their effect on the rate of aging, known as biological age (BA), is unclear. This work aims to test if the intake of a blend of AM3 (150 mg), spermidine (0.6 mg), and hesperidin (50 mg) for 2 months could decrease BA and improve immunity, redox, and inflammatory states. For this, 41 participants (30–63 years) were randomly divided into placebo and supplement groups. The supplement group took two capsules daily with AM3, spermidine, and hesperidin for two months, while the placebo group took capsules containing only calcium phosphate and talcum powder. Before and after the treatment, peripheral blood was collected. Immune function was assessed in leukocytes, redox state in whole-blood cells, erythrocytes, and plasma, and cytokine concentration in both mononuclear cell cultures and plasma. Finally, the Immunity Clock model was applied to determine BA. The results show that the intake of this blend improves the immune functions that constitute the Immunity Clock, decreasing BA by 11 years and reducing the oxidative–inflammatory state of the participants. Therefore, this supplement can be proposed as a strategy to rejuvenate BA and achieve healthy aging.

Towards Bacterial Resistance via the Membrane Strategy: Enzymatic, Biophysical and Biomimetic Studies of the Lipid cis-trans Isomerase of Pseudomonas aeruginosa.

The lipid cis-trans isomerase (Cti) is a periplasmic heme-c enzyme found in several bacteria including Pseudomonas aeruginosa, a pathogen known for causing nosocomial infections. This metalloenzyme catalyzes the cis-trans isomerization of unsaturated fatty acids in order to rapidly modulate membrane fluidity in response to stresses that impede bacterial growth. As a consequence, breakthrough in the elucidation of the mechanism of this metalloenzyme might lead to new strategies to combat bacterial antibiotic resistance. We report the first comprehensive biochemical, electrochemical and spectroscopic characterization of a Cti enzyme. This has been possible by the successful purification of Cti from P. aeruginosa (Pa-Cti) in favorable yields with enzyme activity of 0.41 µmol/min/mg when tested with palmitoleic acid. Through a synergistic approach involving enzymology, site-directed mutagenesis, Raman spectroscopy, Mössbauer spectroscopy and electrochemistry, we identified the heme coordination and redox state, pinpointing Met163 as the sixth ligand of the FeII of heme-c in Pa-Cti. Significantly, the development of an innovative assay based on liposomes demonstrated for the first time that Cti catalyzes cis-trans isomerization directly using phospholipids as substrates without the need of protein partners, answering the important question about the substrate of Cti within the bacterial membrane.

The effect of long term astaxanthin supplementation on the antioxidant status of racing Arabian horses - preliminary study.

Astaxanthin due to its strong antioxidant activity is believed to reduce oxidative stress and therefore is considered as feed additive in pathological conditions and also for the athletes. It is promoted by several equine web portals, however, data supporting that concept in horses is limited. Thus, the aim of this study was to evaluate the effect of astaxanthin supplementation on the parameters of oxidative status in 3 years old, racing Arabian horses during long term observation and the changes related to a single training session of high intensity. Six horses were supplemented with astaxanthin at a dose of 0.52-0.58mg/kg BW and 7 received no supplementation. Astaxanthin supplementation resulted in the increase in total antioxidant status by 31.5%, accompanied by decreases in the amount of total thiobarbituric acid-reactive substances -TBARS and glutathione reductases - GR values by 34.5% and 45.4%, respectively, after 1 month and this effect persisted until the end of the observation. After individual training session the activities of glutathione peroxidases and GR were lower by 69% and 46%, respectively, and TBARS lower by 38% in supplemented horses. These results directly confirmed the beneficial effects of astaxanthin supplementation on the antioxidant status of race horses. Astaxanthin partially counterbalance the training-related oxidative stress, save the horse natural antioxidant defense, and shift the redox status towards a more reducing environment. At the same time, exercise-induced reactive oxygen species production at certain level was maintained and so that contributed to training progress.

Modulation for Redox States of Single-Walled Carbon Nanotubes: Effect of Wrapping Conjugated Polymers.

Controlling the redox states of single-walled carbon nanotubes (SWNTs) is important for the optimization of their real performances in various fields. By means of in situ photoluminescence (PL) spectroelectrochemical measurements, we report a successful modulation for the redox parameters (redox potentials and electrochemical band gap) of (6,5) and (7,5)SWNTs with a simple change in conjugated polymers (CPs) non-covalently wrapped on the nanotubes. The large shift in the band gap (187 meV for (6,5)SWNTs and 101 meV for (7,5)SWNTs) was connected to the prominent difference in the interactions between the CPs and SWNTs as suggested by molecular dynamics (MD) simulations, while a striking difference in the 𝜋-electrons states of CP/SWNTs enabled the tuning of SWNTs' electronic states. Asymmetrical modulation for the reduction potential (LUMO) and oxidation potential (HOMO) of the SWNTs was observed as well. Our results can be promising for a simple but precise control of the electric states of SWNTs.

Subsurface microbial community structure shifts along the geological features of the Central American Volcanic Arc.

Subduction of the Cocos and Nazca oceanic plates beneath the Caribbean plate drives the upward movement of deep fluids enriched in carbon, nitrogen, sulfur, and iron along the Central American Volcanic Arc (CAVA). These compounds fuel diverse subsurface microbial communities that in turn alter the distribution, redox state, and isotopic composition of these compounds. Microbial community structure and functions vary according to deep fluid delivery across the arc, but less is known about how microbial communities differ along the axis of a convergent margin as geological features (e.g., extent of volcanism and subduction geometry) shift. Here, we investigate changes in bacterial 16S rRNA gene amplicons and geochemical analysis of deeply-sourced seeps along the southern CAVA, where subduction of the Cocos Ridge alters the geological setting. We find shifts in community composition along the convergent margin, with communities in similar geological settings clustering together independently of the proximity of sample sites. Microbial community composition correlates with geological variables such as host rock type, maturity of hydrothermal fluid and slab depth along different segments of the CAVA. This reveals tight coupling between deep Earth processes and subsurface microbial activity, controlling community distribution, structure and composition along a convergent margin.

Biochemical and proteomic approaches to investigating effects of IAA-aspartate in pea (Pisum sativum L.) seedlings during osmotic shock.

Osmotic shock is the first step of high salt or drought action that involves biochemical and molecular changes during plant response to these unfavorable conditions. Indole-3-acetyl-aspartate (IAA-aspartate, IAA-Asp) is the main amide conjugate of auxin in pea (Pisum sativum L.) tissues. Although the exact molecular mechanism of the IAA-Asp action is unknown, this conjugate's indole-3-acetic acid (IAA)-independent biological activity has been observed during physiological and stress conditions. In this work, we investigated the effect of IAA-Asp alone, as well as in combination with NaCl or polyethylene glycol (PEG) (osmotic shock) on reduced/oxidized glutathione (GSH/GSSG) ratio, activities of enzymes modulating glutathione concentration, protein S-glutathionylation, and IAA homeostasis. We did not observe the hydrolysis of IAA-Asp to IAA in pea seedlings, which, together with other results, suggests that IAA-Asp modulates plant response to abiotic stimuli independently of IAA. Moreover, despite the effect of IAA-Asp on the enzymes responsible for IAA conjugation, no changes in this phytohormone level were visible. Furthermore, 3h plant treatment with IAA-Asp increased the activity of glutathione reductase (GR), which correlates with an elevated GSH/GSSG ratio. On the contrary, more extended (48h) incubation with IAA-Asp diminished the GSH/GSSG ratio and increased the activity of glutathione peroxidase (GPX). IAA-Asp reduced GR activity during salt treatment but did not affect the GSH/GSSG ratio. Similarly, under plant incubation with PEG, IAA-Asp did not change the GSH/GSSG ratio but increased glutathione S-transferase (GST) activity. We also analyzed the effect of IAA-Asp on pea protein S-glutathionylation. Increased S-glutathionylation of heat shock 70 kDa protein (HSP70) was observed after plant treatment with IAA-Asp, PEG, or IAA-Asp combined with PEG. The proteomic analysis also revealed that IAA-Asp diminished S-glutathionylation of lipoxygenase during plant incubation with PEG. Thus, we suggest that IAA-Asp modulates redox status in pea during oxidative stress and under normal physiological conditions.

Highly Dispersed ZnO Sites in a ZnO/ZrO2 Catalyst Promote Carbon Dioxide‐to‐Methanol Conversion

AbstractZnO/ZrO2 catalysts have shown better activity in the CO2 hydrogenation to methanol compared with single component counterparts, but the interaction between ZnO and ZrO2 is still poorly understood. In particular, the effect of the ZrO2 support phase (tetragonal vs. monoclinic) was not systematically explored. Here, we have synthesized ZnO/ZrO2 catalysts supported on tetragonal ZrO2 (ZnO/ZrO2‐t) and monoclinic ZrO2 (ZnO/ZrO2‐m), which resulted in the formation of different ZnOx species, consisting of sub‐nanometer ZnO moieties and large‐sized ZnO particles, respectively. ZnO/ZrO2‐t exhibited a higher methanol selectivity (81 vs. 39 %) and methanol yield (1.25 vs. 0.67 mmol g−1 h−1) compared with ZnO/ZrO2‐m. The difference in performance was attributed to the redox state and degree of dispersion of Zn, based on spectroscopy and microscopy results. ZnO/ZrO2‐t had a high density of ZnOx‐ZrOy sites, which favored the formation of active HCOO* species and enhanced the yield and selectivity of methanol along the formate pathway. Such ZnO clusters were further dispersed on ZrO2‐t during catalysis, while larger ZnO particles on ZnO/ZrO2‐m remained stable throughout the reaction. This study shows that the phase of ZrO2 supports can be used to control the dispersion of ZnO and the catalyst surface chemistry, and lead to enhanced catalytic performance.

Delocalized Polarons in Diketopyrrolopyrrole‐Based Conjugated Polymers: Implications for Near‐Infrared Electrochromism and Beyond

AbstractConjugated polymers with delocalized polarons and near‐infrared (IR) absorption properties are promising materials for applications in electrochemical devices. However, the poor stability of low bandgap polymers in electrochemical redox conditions limits the realization of such devices. Herein, a new family of near‐IR absorbing conjugated polymers based on diketopyrrolopyrrole (DPP) derivatives with methoxy substituents to achieve reversible p‐type electrochemical doping with bistable near‐IR electrochromism is designed. The extent of volumetric doping in various electrolytes using cyclic voltammetry and spectroelectrochemistry for optimal electrochemical kinetics and near‐IR contrast is systematically investigated. Further, the spray‐coated films of polymers display high open circuit memory as the methoxylation is increased on the polymer backbone. The contrasting electrochromic memory and kinetics observed for these polymers are mainly ascribed to two factors; i) the effect of backbone structure on the spatial extent of polaron delocalization, and ii) the ionization energy of the polymers. The utility of DPP‐based polymers as energy‐efficient electrochromic optical attenuators (EVOAs) with high near‐IR coloration efficiencies, and an optical attenuation value of 5.1 dB at 1.3 and 1.5 µm wavelengths is demonstrated. Furthermore, the experimental findings are corroborated with theoretical studies to establish that the polaron delocalization length is central to the performance of the device.

PATH-52. DIFFERENCES IN GENE EXPRESSION, GENOME-WIDE METHYLATION AND METABOLITES IN ADULT DIFFUSE GLIOMAS

Abstract Metabolic reprogramming is a hallmark of cancer, including diffuse gliomas. IDH1 and IDH2 are key enzymes linking cellular metabolism to epigenetic regulation and redox states. IDH1/IDH2 enzymes catalyze the conversion of isocitrate to α-ketoglutarate, while the mutant enzymes increase the production of D-2-hydroxyglutarate, an oncometabolite that induces epigenetic changes, leading to gene expression alterations. Understanding how epigenetic alterations affect metabolic gene expression and metabolite levels in diffuse gliomas could help identify diagnostic biomarkers and therapeutic targets. We studied the expression of metabolism-related genes, metabolites, and genome-wide methylation status, which will facilitate an integral understanding of the metabolic changes in IDH-mutant and IDH-wildtype gliomas. Study design included 47 fresh frozen tissue samples. RNA was extracted and used for gene expression analysis using the NanoString platform (nCounter® Metabolic Pathways Panel), while extracted DNA was used for targeted sequencing with a panel interrogating 600 genes and for genome-wide methylation analysis using the Illumina Epic v2. In addition, unbiased metabolomic analysis by mass spectrometry was performed in 25 tissue and CSF samples out of 47 samples. Methylation status, gene expression and metabolite levels were compared between IDH-mutant and IDH-wildtype gliomas. Results showed significant differences in DNA methylation, gene expression and metabolites between IDH-mutant and IDH-wildtype gliomas. UPP1, an enzyme involved in uracil metabolism, was studied in depth to understand the interplay between DNA methylation, gene expression, and metabolic reprogramming in diffuse glioma. Epigenetic analysis revealed that the CpG sites within the UPP1 gene displayed reduced methylation in IDH wild-type compared to IDH-mutant tumors. IDH wild-type tumors showed higher UPP1 expression compared to their IDH-mutant counterparts. Consequently, we observed higher levels of uracil in tissue and CSF samples from patients with IDH wild-type gliomas. These data provide a framework to study the relationship between mutations, methylation, gene expression and metabolism in diffuse gliomas.

EXTH-61. TOWARDS A QUANTUM THERAPY FOR GLIOBLASTOMA: A NEW THERAPEUTIC PARADIGM IN MEDICINE

Abstract BACKGROUND A cell operates as an interconnected bioelectrical circuit, utilising electron transfer processes for intracellular communication, with cytochrome c (Cyt c) playing a pivotal role. The redox processes of Cyt c, occurring via electron tunnelling, are essential for its translocation into the cytosol and modulation of its conformation to bind apoptotic protease activating factor 1. This highlights the need for novel technologies capable of interacting with these processes at the atomic scale to control downstream effects and induce apoptosis in cancer cells. METHODS We demonstrate that ‘bio-nanoantennae’, when supplied with an electrical current, enable quantum biological tunnelling for electron transfer (QBET) and facilitate cellular apoptosis in patient-derived IDH wild-type glioblastoma from both the infiltrative tumour margin and proliferative core. The bio-nanoantennae were constructed from gold nanoparticles functionalised with reduced Cyt c and zinc porphyrin as a redox couple. RESULTS Electrical polarisation of these bio-nanoantennae via resonant alternating currents in preclinical glioblastoma cells led to decreased metabolic activity and reduced cell viability by oxidizing Cyt c, thus inducing cellular stress. No significant effect was observed in healthy human astrocyte counterparts. The cytosol localised bio-nanoantennae induced differential gene expression related to ion channels, apoptosis, cancer proliferation and tumour suppression upon activation, in tumour relative to astrocyte cell populations. The bio-nanoantennae were also tested in 3D glioblastoma spheroid models, showing similar effects, and in vivo studies demonstrated a significant reduction in glioblastoma xenograft tumour size. CONCLUSION We propose that bio-nanoantennae modulate the redox state of Cyt c under an electrical field through QBET. To validate this, we investigated the tunnel junction energy and plasmon resonance scattering, and developed a mathematical model to explain the system’s behaviour. This innovative wireless electrical–molecular nanodevice, capable of inducing cancer cell apoptosis, paves the way for further applications of quantum signalling as a new (non-pharmacological) therapeutic paradigm.

High-Resolution Reconstruction of Oxidation–Reduction Conditions: Raman Spectroscopy and μ-XRF Analysis of Manganese Nodule and Crust on Tabletop of Western Pacific Magellan Seamounts

Ferromanganese (Fe-Mn) deposits are widely used in paleoenvironmental reconstructions owing to their mineralogical and geochemical properties. We analyzed Fe-Mn deposits using micro-X-ray fluorescence and Raman spectroscopy to study the paleo-ocean environment. Samples were collected from the OSM-XX seamount in the western Pacific. The Fe-Mn crust was divided into three parts: phosphatized, massive non-phosphatized, and porous non-phosphatized. Vernadite was identified in all layers. Furthermore, in the nodule, high values of Mn, Ni, and Cu were observed near the nucleus, with vernadite and todorokite, and these values decreased outward. A high Mn/Fe ratio near the nucleus indicates early diagenetic processes. Formation of Fe-Mn nodules began around 19–16 Ma, and this period corresponded to a minor phosphatization event and persistent reducing conditions. From 11–10 Ma, the Mn/Fe and Co/Mn ratios decreased due to the formation of a western Pacific warm pool during this period. Subsequently, with the opening of the Indonesian seaway and global cooling, the Mn/Fe and Co/Mn ratios in the Fe-Mn deposits increased again. The comparative analysis of variations in Mn/Fe ratio and vernadite crystallinity in the Fe-Mn deposits confirmed that it is possible to reconstruct paleo-productivity and redox condition changes in the western Pacific Magellan Seamount.

Sedimentary facies controlled biogeochemical process of biotic extinction and turnover across the Cambrian SPICE event

The Steptoean positive carbon isotope excursion (SPICE) event, one of the largest carbon cycle perturbations in the Cambrian, coincides with shallow-shelf-fauna extinction and plankton revolution (critical transition of plankton). The event is globally documented, but biogeochemical responses of these biotic evolutions in varying facies environments are not well understood. Here high-resolution paired δ18Ocarb, δ13Ccarb and δ13Corg datasets from varied paleodepth environments in the Tarim Basin, NW China reveal facies-dependent signatures of the event, with globally synchronous patterns but notable intra-basinal variability. Shallow marine facies record the end-Marjuman extinction with a distinct negative δ13Corg excursion prior to the event, while the transitional facies region marks twice positive δ13C excursions corresponding to an asynchronous plankton revolution from shallow and deep areas during the event. The varying isotope responses are interpreted in the context of primary productivity and redox conditions, with deeper basins recording more 13C enriched signals (i.e., higher δ13C) due to greater organic matter preservation under anoxic conditions, compared to the platform area. The biotic extinction, the planktonic revolution and the interaction of organisms along the shallow to deep marine depth gradient were reflected by the significant isotopic shifts recorded during the event, suggesting depth-dependent biogeochemical processes that shaped marine ecosystems.

Dark Anaerobic Conditions Induce a Fast Induction of the Xanthophyll Cycle in Chlamydomonas reinhardtii When Exposed to High Light

Background: Dark anaerobiosis promotes the acidification of the thylakoid lumen and a reduction in the plastoquinone (PQ) pool. The relationship between the reduction in the PQ pool in the dark and the induction of the xanthophyll cycle under high light stress was investigated in Chlamydomonas reinhardtii. Methods: To achieve a comprehensive oxidative/reductive (aerobic/anaerobic conditions) state of the PQ pool, cultures were bubbled with air or nitrogen for 4 h. To induce the xanthophyll cycle, the cultures were then irradiated with 1200 µmolphotons m−2 s−1 white light for 1 h. Results: The anaerobic cultures exhibited a stronger induction of the xanthophyll cycle with a 3.4-fold higher de-epoxidation state than the aerobic cultures. Chlorophyll fluorescence measurements showed that this response was influenced by the previous redox state of the PQ pool, and that dark anaerobiosis triggers physiological responses, such as exposure to high light. Thus, the photosynthetic apparatus in anaerobic cultures was already alerted, at the moment of high light exposure, to give an appropriate response to the stress with a stronger induction of the xanthophyll cycle than in aerobic cultures. Conclusions: Our results provide new information on the importance of the redox signaling pathway and highlight the importance of the reductive conditions of the PQ pool in regulating the physiological responses of photosynthetic organisms to stress.

Heart function enhancement with Nrf2-activating antioxidant in acute Y-strain Chagas disease, not in chronic Colombian or Y-strain.

Oxidative stress promotes T. cruzi growth and development of chronic Chagas heart dysfunction. However, the literature contains gaps that must be fulfilled, largely due to variations in parasite DTU sources, cell types, mouse strains, and tools to manipulate redox status. We assessed the impact of oxidative environment on parasite burden in cardiomyoblasts and the effects of the Nrf2-inducer COPP on heart function in BALB/c mice infected with either DTU-II Y or DTU-I Colombian T. cruzi strains. Treatment with antioxidants CoPP, apocynin, resveratrol, and tempol reduced parasite burden in cardiomyoblasts H9C2 for both DTUI- and II-strains, while H2O2 increased it. CoPP treatment improved electrical heart function when administered during acute stage of Y-strain infection, coinciding with an overall trend towards increased survival and reduced heart parasite burden. These beneficial effects surpassed those of trypanocidal benznidazole, implying that CoPP directly affects heart physiology. CoPP treatment had beneficial impact on heart systolic function when performed during acute and evaluated during chronic stage. No impact of CoPP on heart parasite burden, electrical, or mechanical function was observed during the chronic stage of Colombian-strain infection, despite previous demonstrations of improvement with other antioxidants. Treatment with CoPP also did not improve heart function of mice chronically infected with Y-strain. Our findings indicate that amastigote growth is responsive to changes in oxidative environment within heart cells regardless of the DTU source, but CoPP influence on heart parasite burden in vivo and heart function is mostly confined to the acute phase. The nature of the antioxidant employed, T. cruzi DTU, and the stage of disease, emerge as crucial factors to consider in heart function studies.

Sedimentary Environment Reconstruction and Organic Matter Enrichment Mechanisms in Various Lithofacies of the Lacustrine Shale: A Case Study of the Da’anzhai Member, Central Sichuan Basin, China

Jurassic lacustrine shale in the Sichuan Basin is a focal exploration area in China, while the pronounced heterogeneity presents challenges, necessitating detailed research as a prerequisite. This study aims at the Jurassic Ziliujing Formation Da’anzhai shale in the central Sichuan Basin, systematically characterizing its geological features. Employing geochemical methods, we reconstructed the paleo-sedimentary environments and explored the mechanisms behind the organic matter enrichment. The findings reveal that the Da’anzhai shale exhibits three lithofacies: organic-rich argillaceous shale (ORA), organic-poor argillaceous shale (OPA), and organic-rich mixed shale (ORM). The sedimentary period was marked by a warm and humid climate, predominantly depositing in anoxic environments with freshwater to brackish conditions. The watershed areas that are provenance sources for the shale clastics are experiencing strong weathering. Significant differences in the sedimentary environments of various lithofacies’ shale were observed. Redox conditions and paleoclimate were identified as the primary factors controlling organic matter enrichment in the Da’anzhai shale of the study area. Salinity also played a role in organic matter enrichment, while terrigenous debris influx and paleo-productivity did not exert a significant controlling effect on organic matter enrichment. Utilizing the reconstructed ancient sedimentary environments, we developed sedimentary models for different lithofacies’ shale, contributing to a deeper understanding of lithofacies’ diversity and the mechanisms governing organic matter enrichment in lacustrine environments. This study provides new information for further understanding the response mechanism of lacustrine shales to the Toarcian Oceanic Anoxic Event in the Early Jurassic from the perspective of elemental geochemistry.