Redox Changes Research Articles

Investigating cerium redox changes between aluminosilicate glass and melt: A multispectroscopic approach.

Redox control of glasses is paramount both to their fusion process and to obtaining the desired properties of high technological glasses. However, the link between melting parameters, such as temperature, furnace atmosphere, or quenching rate, and the redox state of the final products is poorly understood. In this work, in situ x-ray absorption near-edge structure (XANES) data at Ce L3-edge data were acquired at high temperatures on cerium-containing sodium aluminosilicate glasses, allowing the determination of thermodynamic constants necessary to predict the cerium redox state over a wide temperature range (900-1500 °C). The results obtained were compared to the Raman spectra of samples quenched at different temperatures. Our findings demonstrate that the quench performed was fast enough to block the cerium oxidation state, meaning the redox measured at room temperature is representative of a high temperature state. This was further verified by room temperature Raman spectroscopy, where a relationship was found between the spectra and melting conditions. Wet chemical analysis, XANES at Ce L3-edge, Raman spectroscopy, and optical absorption spectroscopy were successfully used to determine the redox state of cerium in aluminosilicates.

Abstract 444: Lipid exposure re-wires cellular metabolism away from glycolysis toward the serine pathway conferring oncogenic properties to non-transformed breast cells

Abstract Introduction. A lipid metabolism gene signature is associated with the risk of estrogen negative breast cancer (ER-BC). In vitro, lipid exposure alters histone methylation affecting gene expression and increases flux through various metabolic reactions including those involved in serine, one-carbon, glycine (SOG) and methionine. We hypothesized that the metabolism of lipids in preference to glucose and glutamine results in a metabolic shift toward the serine pathway increasing S-adenosylmethionine (SAM) leading to histone methylation increases and changes in gene expression. Methods. MCF-10A cells exposed to octanoic acid (OA) were utilized for U13C-glucose tracing. SAM, glutathione (GSH) and 2-hydroxyglutarate (2-HG) concentrations were measured following treatment with OA ± the PHGDH inhibitor CBR-5884. ROS-induced redox changes were monitored live in cells transduced with ORP1-roGFP2 vectors. CUT&RUN was performed for H3K4me3. Expression of OA-induced genes was measured by rt-qPCR upon exposure to OA ± CBR-5884 or OA ± the histone methyltransferase (HMT) inhibitor Piribedil. Alkaline comet assay was done to detect DNA breaks. Single-cell RNA-seq (scRNAseq) was performed on tissue-derived breast microstructures exposed to ± OA. Results. Upon OA treatment, the Cancer index increased and 1C-THF was redirected to the methionine cycle increasing flux to methylation. OA significantly increased the production of SAM, GSH and 2-HG after 15 min. Blocking the first enzyme in the serine pathway, PHGDH, prevented these increases. After 5 min OA exposure, mitochondrial and nuclear ROS increased significantly (p < 0.0001), peaking at 15 min. H3K4me3 CUT&RUN revealed 661 differential peaks (FDR < 0.05) comparing OA to control. 73% of H3K4me3 OA-associated peaks were in regulatory regions of OA-induced genes (FDR < 0.01) including neural, EMT and ER- BC related genes. Motif analysis revealed an overrepresentation of binding sites for serine pathway transcriptional activators ATF3/4 (p < 0.05). Blocking PHGDH or HMT prevented OA-induced gene expression changes. Alkaline comet assay showed that OA significantly increased comet tails. scRNAseq revealed OA increased the numbers of cells within all cell clusters expressing ATF3 and PHGDH. Also observed was an increase in the percentage of basal BSL1, luminal progenitor LP3 and hormone sensing HS1 cells. Conclusions. Metabolism of OA results in a metabolic shift toward the SOG and methionine increasing the production of SAM, GSH and 2-HG which have implications for oncogenesis. The increased SAM fosters epigenetic phenotypic plasticity via altered histone methylation. The increased proportion of specific cell types likely reflects the survival of cells able to mitigate oxidative stress. Increased 2-HG may produce metabolic BRCAness by inhibiting 2-oxoglutarate-dependent dioxygenases. Citation Format: Mariana Bustamante Eduardo, Gannon Cottone, Shiyu Liu, Flavio R. Palma, Maria Paula Zappia, Abul B.M.M.K. Islam, Elizaveta V. Benevolenskaya, Maxim V. Frolov, Jason Locasale, Marcelo G. Bonini, Navdeep S. Chandel, Seema Khan, Susan Clare. Lipid exposure re-wires cellular metabolism away from glycolysis toward the serine pathway conferring oncogenic properties to non-transformed breast cells [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2024; Part 1 (Regular Abstracts); 2024 Apr 5-10; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2024;84(6_Suppl):Abstract nr 444.

Dynamics and interplay of photosynthetic regulatory processes depend on the amplitudes of oscillating light.

Plants have evolved multiple regulatory mechanisms to cope with natural light fluctuations. The interplay between these mechanisms leads presumably to the resilience of plants in diverse light patterns. We investigated the energy-dependent nonphotochemical quenching (qE) and cyclic electron transports (CET) in light that oscillated with a 60-s period with three different amplitudes. The photosystem I(PSI) and photosystem II (PSII) function-related quantum yields and redox changes of plastocyanin and ferredoxin were measured in Arabidopsis thaliana wild types and mutants with partial defects in qE or CET. The decrease in quantum yield of qE due to the lack of either PsbS- or violaxanthin de-epoxidase was compensated by an increase in the quantum yield of the constitutive nonphotochemical quenching. The mutant lacking NAD(P)H dehydrogenase(NDH)-like-dependent CET had a transient significant PSI acceptor side limitation during the light rising phase under high amplitude of light oscillations. The mutant lacking PGR5/PGRL1-CET restricted electron flows and failed to induce effective photosynthesis control, regardless of oscillation amplitudes. This suggests that PGR5/PGRL1-CET is important for the regulation of PSI function in various amplitudes of light oscillation, while NDH-like-CET acts' as a safety valve under fluctuating light with high amplitude. The results also bespeak interplays among multiple photosynthetic regulatory mechanisms.

Rapid Electrochemical Detection of Bacterial Sepsis in Cirrhotic Patients: A Microscaffold-Based Approach for Early Intervention.

Sepsis is a dysregulated inflammatory response leading to multiple organ failure. Current methods of sepsis detection are time-consuming, involving nonspecific clinical signs, biomarkers, and blood cultures. Hence, efficient and rapid sepsis detection platforms are of utmost need for immediate antibiotic treatment. In the current study, a noninvasive rapid monitoring electrochemical sensing (ECS) platform was developed for the detection and classification of plasma samples of patients with liver cirrhosis by measuring the current peak shifts using the cyclic voltammetry (CV) technique. A total of 61 hospitalized cirrhotic patients with confirmed (culture-positive) or suspected (culture-negative) sepsis were enrolled. The presence of bacteria in the plasma was observed by growth kinetics, and for rapidness, the samples were co-encapsulated in microscaffolds with carbon nanodots that were sensitive enough to detect redox changes occurring due to the change in the pH of the surrounding medium, causing shifts in current peaks in the voltammograms within 2 h. The percentage area under the curve for confirmed infections was 94 and that with suspected cases was 87 in comparison to 69 and 71 with PCT, respectively. Furthermore, the charge was measured for class identification. The charge for LPS-absent bacteria ranged from -400 to -600 μC, whereas the charge for LPS-containing bacteria class ranged from -290 to -300 μC. Thus, the developed cost-effective system was sensitive enough to detect and identify bacterial sepsis.

Stable hydrogen and oxygen isotope geochemistry of Fe3+-rich, interstratified clay minerals from seafloor hydrothermal sites

Chemical and structural complexities in interstratified clay minerals arising from mineral transformations and evolving formation conditions should be recorded in their stable isotope signatures. This paper examines the controls on the stable hydrogen and oxygen isotope compositions of Fe3+-rich, glauconite-nontronite, talc-nontronite and talc-saponite from submarine hydrothermal sites, with a focus on the Red Sea Atlantis II Deep. Values of δ18O became less positive in the order nontronite > glauconite-nontronite > talc-nontronite > talc-saponite, yielding oxygen isotope temperatures ranging from ∼40 °C for nontronite to ∼135–300 °C for talc-saponite. These clay minerals have low δ2H, ranging from −145 to −127‰ for talc-nontronite, −135‰ for nontronite, −129 to −85‰ for glauconite-nontronite, and −95 to −59‰ for talc-saponite. The clay mineral-water hydrogen isotope fractionation is strongly affected by Fe3+ content, with increasing structural Fe3+ causing progressive weakening of O-H bonds. The large ionic radius and high charge of Fe3+ cause it to be more poorly shielded by surrounding oxygen from hydroxyl hydrogen relative to other octahedral or tetrahedral cations. The resulting lengthening of O-H bonds favours 1H over 2H. Our results confirm that Fe-rich phases, such as nontronite-glauconite, are produced at the lowest temperatures and Mg-rich phases, such as talc-saponite, are formed at the highest temperatures in seafloor hydrothermal environments. Evolving fluid chemistry and fluid pathways during clay mineral formation are also important. Glauconite layer formation from precursor nontronite likely occurred during diagenesis; redox changes causing Fe-reduction and an increase in layer charge facilitated interlayer K-fixation. Talc-saponite compositions vary with temperature and fluid chemistry, forming at variable sediment depths depending on access to the hottest hydrothermal fluids.

Multiomics Characterization of a Less Invasive Microfluidic-Based Cell Sorting Technique.

Fluorescence-activated cell sorting (FACS) is a specialized technique to isolate specific cell subpopulations with a high level of recovery and accuracy. However, the cell sorting procedure can impact the viability and metabolic state of cells. Here, we performed a comparative study and evaluated the impact of traditional high-pressure charged droplet-based and microfluidic chip-based sorting on the metabolic and phosphoproteomic profile of different cell types. While microfluidic chip-based sorted cells more closely resembled the unsorted control group for most cell types tested, the droplet-based sorted cells showed significant metabolic and phosphoproteomic alterations. In particular, greater changes in redox and energy status were present in cells sorted with the droplet-based cell sorter along with larger shifts in proteostasis. 13C-isotope tracing analysis on cells recovering postsorting revealed that the sorter-induced suppression of mitochondrial TCA cycle activity recovered faster in the microfluidic chip-based sorted group. Apart from this, amino acid and lipid biosynthesis pathways were suppressed in sorted cells, with minimum impact and faster recovery in the microfluidic chip-based sorted group. These results indicate microfluidic chip-based sorting has a minimum impact on metabolism and is less disruptive compared to droplet-based sorting.

Development of (NO)Fe(N2S2) as a Metallodithiolate Spin Probe Ligand: A Case Study Approach.

ConspectusThe ubiquity of sulfur-metal connections in nature inspires the design of bi- and multimetallic systems in synthetic inorganic chemistry. Common motifs for biocatalysts developed in evolutionary biology include the placement of metals in close proximity with flexible sulfur bridges as well as the presence of π-acidic/delocalizing ligands. This Account will delve into the development of a (NO)Fe(N2S2) metallodithiolate ligand that harnesses these principles. The Fe(NO) unit is the centroid of a N2S2 donor field, which as a whole is capable of serving as a redox-active, bidentate S-donor ligand. Its paramagnetism as well as the ν(NO) vibrational monitor can be exploited in the development of new classes of heterobimetallic complexes. We offer four examples in which the unpaired electron on the {Fe(NO)}7 unit is spin-paired with adjacent paramagnets in proximal and distal positions.First, the exceptional stability of the (NO)Fe(N2S2)-Fe(NO)2 platform, which permits its isolation and structural characterization at three distinct redox levels, is linked to the charge delocalization occurring on both the Fe(NO) and the Fe(NO)2 supports. This accommodates the formation of a rare nonheme {Fe(NO)}8 triplet state, with a linear configuration. A subsequent FeNi complex, featuring redox-active ligands on both metals (NO on iron and dithiolene on nickel), displayed unexpected physical properties. Our research showed good reversibility in two redox processes, allowing isolation in reduced and oxidized forms. Various spectroscopic and crystallographic analyses confirmed these states, and Mössbauer data supported the redox change at the iron site upon reduction. Oxidation of the complex produced a dimeric dication, revealing an intriguing magnetic behavior. The monomer appears as a spin-coupled diradical between {Fe(NO)}7 and the nickel dithiolene monoradical, while dimerization couples the latter radical units via a Ni2S2 rhomb. Magnetic data (SQUID) on the dimer dication found a singlet ground state with a thermally accessible triplet state that is responsible for magnetism. A theoretical model built on an H4 chain explains this unexpected ferromagnetic low-energy triplet state arising from the antiferromagnetic coupling of a four-radical molecular conglomerate. For comparison, two (NO)Fe(N2S2) were connected through diamagnetic group 10 cations producing diradical trimetallic complexes. Antiferromagnetic coupling is observed between {Fe(NO)}7 units, with exchange coupling constants (J) of -3, -23, and -124 cm-1 for NiII, PdII, and PtII, respectively. This trend is explained by the enhanced covalency and polarizability of sulfur-dense metallodithiolate ligands. A central paramagnetic trans-Cr(NO)(MeCN) receiver unit core results in a cissoid structural topology, influenced by the stereoactivity of the lone pair(s) on the sulfur donors. This {Cr(NO)}5 radical bridge, unlike all previous cases, finds the coupling between the distal Fe(NO) radicals to be ferromagnetic (J = 24 cm-1).The stability and predictability of this S = 1/2 moiety and the steric/electronic properties of the bridging thiolate sulfurs suggest it to be a likely candidate for the development of novel molecular (magnetic) compounds and possibly materials. The role of synthetic inorganic chemistry in designing synthons that permit connections of the (NO)Fe(N2S2) metalloligand is highlighted as well as the properties of the heterobi- and polymetallic complexes derived therefrom.

Redox cycling of straw-amended soil simultaneously increases iron oxide crystallinity and the content of highly disordered organo-iron(III) solids

Iron speciation in soils is influenced largely by its redox state, but the extent of and controls on Fe speciation during recurrent reduction and oxidation events are not fully understood. To investigate the effects of organic matter (OM) inputs and the frequency and duration of redox oscillations on soil Fe speciation, we conducted redox-oscillation experiments with topsoil from a Fluvisol mixed with rice straw (0, 10, 50 g/kg organic carbon, OC). The soil was initially dominated by short-range ordered (SRO) Fe(III) solids and subjected to 14- and 28-day reduction–oxidation cycles for 112 days, with the time spent under anoxic and oxic conditions maintained at 6:1. Reduction was initiated by flooding reactors with artificial river water. To simulate leaching conditions, soil re-oxidation was achieved by air-drying soil after removal of reacted solutions. Fresh river water was then added for each new redox cycle. We monitored changes in solution composition (Eh, pH, Fe(II), total Fe, OC, and Si) and assessed changes of solid-phase Fe speciation by selective extractions, X-ray absorption spectroscopy, and 57Fe Mössbauer spectroscopy. Dissolved OC and Fe increased with increasing straw addition, but decreased in each treatment through consecutive reduction intervals. Release rates of dissolved Fe and OC were highly correlated, implying that microbial reduction of soil Fe(III) solids was fostered by straw amendments. Reduction-induced losses of OC and Fe from straw amended soil were amplified at high redox frequency. Ferrous Fe did not detectably accumulate in the solid phase upon repeated soil oxidation. Although Fe(III)-poor phyllosilicates gained in relative importance in redox-cycled soils, their fraction was hardly affected during redox cycling. Instead, straw additions led to an enhanced depletion of ferrihydrite during soil redox cycling and a relative enrichment of highly disordered Fe(III) species [‘very SRO (vSRO) Fe(III) solids’], which remained only partially ordered in 5-K Mössbauer spectra and likely consisted predominantly of polynuclear organic Fe complexes. The depletion of ferrihydrite in straw-amended soils after 112 days was greater in the 14-day cycle than in the 28-day cycle experiment and accompanied by a less pronounced enrichment of vSRO Fe(III) solids. The crystallinity of distinct Fe oxides (ferrihydrite, lepidocrocite, and hematite) increased during soil redox cycling especially in straw-amended soils, but without noticeable ferrihydrite conversion into crystalline Fe oxides. The increase in the crystallinity of distinct Fe oxides after 112 days was greater at low redox frequency in straw-free soil, however this frequency effect was suppressed by straw additions. Longer soil redox cycling (112 vs. 56 days) increased the crystallinity of distinct Fe oxides, which was most pronounced at high straw levels and low redox frequency. Our results imply that redox changes in SRO Fe oxide- and OM-rich soils can cause a relative enrichment of more crystalline Fe oxides, while still maintaining a pool of vSRO Fe(III) solids. We conclude that soil redox oscillations can lead to divergent transformation pathways of Fe oxides, which concomitantly increase bulk Fe-oxide crystallinity and generate increasing fractions of highly disordered Fe(III) solids on comparatively short time scales. In addition, our study suggests that faster redox cycling in soils with ample electron donor supply and water leaching leads to higher element exports (e.g., OC, metal(loid)s) from soil due to weekly redox pulsing than more slowly alternating redox conditions.

A shift in redox conditions near the Ediacaran/Cambrian transition and its possible influence on early animal evolution, Corumbá Group, Brazil

The Ediacaran–Cambrian transition witnessed some of the most important biological, tectonic, climatic and geochemical changes in Earth’s history. Of utmost importance for early animal evolution is the likely shift in redox conditions of bottom waters, which might have taken place in distinct pulses during the late Ediacaran and early Paleozoic. To track redox changes during this transition, we present new trace element, total organic carbon and both inorganic and organic carbon isotopes, and the first iron speciation data on the Tamengo and Guaicurus formations of the Corumbá Group in western Brazil, which record important paleobiological changes between 555 Ma to < 541 Ma. The stratigraphically older Tamengo Formation is composed mainly of limestone with interbedded marls and mudrocks, and bears fragments of upper Ediacaran biomineralized fossils such as Cloudina lucianoi and Corumbella werneri. The younger Guaicurus Formation represents a regional transgression of the shallow carbonate platform and is composed of a homogeneous fine-grained siliciclastic succession, bearing meiofaunal bilateral burrows. The new iron speciation data reveal predominantly anoxic and ferruginous (non-sulfidic) bottom water conditions during deposition of the Tamengo Formation, with FeHR/FeT around 0.8 and FePy/FeHR below 0.7. The transition from the Tamengo to the Guaicurus Formation is marked by a stratigraphically rapid drop in FeHR/FeT to below 0.2, recording a shift to likely oxic bottom waters, which persist upsection. Redox-sensitive element (RSE) concentrations are muted in both formations, but consistent with non-sulfidic bottom water conditions throughout. We interpret the collected data to reflect a transition between two distinct paleoenvironmental settings. The Tamengo Formation represents an environment with anoxic bottom waters, with fragments of biomineralized organisms that lived on shallower, probably mildly oxygenated surficial waters, and that were then transported down-slope. Similar to coeval successions (e.g., the Nama Group in Namibia), our data support the hypothesis that late Ediacaran biomineralized organisms lived in a thin oxygenated surface layer above a relatively shallow chemocline. The Guaicurus Formation, on the other hand, records the expansion of oxic conditions to deeper waters during a sea level rise. Although the relationship between global biogeochemical changes and the activities of early bioturbators remains complex, these results demonstrate an unequivocal synchronous relationship between oxygenation of the Corumbá basin and the local appearance of meiofaunal bioturbators.

Olenekian sulfur isotope records: Deciphering global trends, links to marine redox changes and faunal evolution

The sulfur (S) isotope composition of carbonate associated sulfate (CAS) in carbonate rocks has been used to assess variations in paleo-oceanographic redox conditions and its relationship to biotic changes in Earth's history, including the Smithian – Spathian transition. However, previous CAS studies of the Olenekian are mostly based on nearshore continental shelf sections and report highly variable δ34S values mostly offset from those of contemporaneous evaporites, casting doubt on the utility of the CAS proxy during this interval. The current study presents new CAS isotopic data from three well-dated carbonate successions which were deposited in continental shelf (Qiakong) and offshore marine (Wadi Musjah and Jebel Aweri) environments during the Olenekian (Smithian – Spathian). The aim of the study was to constrain the temporal and spatial variations in sulfur cycling and its relation to marine redox and faunal changes across the Smithian – Spathian transition (ca. 250.5–248.8 Ma). The CAS dataset is complemented by rare earth element (REE) concentration data and thin section petrography. Using a suite of optical and geochemical techniques, the preservation of near-primary CAS isotopic information in the studied samples is evaluated. Results indicate that of the three sections investigated, the offshore sections mostly preserve near-primary marine sulfate S-isotope compositions while the continental shelf Qiakong section suffers from post-depositional alteration of CAS. Comparisons of our new, as well as previously published CAS δ34S data, with the evaporite δ34S record suggests that although Olenekian CAS δ34S values may have been modified by diagenetic processes, a global and primary seawater δ34S trend can be delineated as follows: seawater δ34S values increased across the middle Smithian and Smithian – Spathian boundary (SSB). Based on our new CAS data, this increase was in the order of 9 ‰ over ca. 1.14 million years. Other short-term variability in the CAS δ34S record most likely reflects diagenetic processes. The middle Smithian to SSB δ34S increase is attributed to a global increase in microbial sulfate reduction and pyrite burial associated with decreasing ocean dissolved oxygen during this time. Calculations of the rate of sulfur cycling and box modeling constraints indicate that Olenekian marine sulfur cycle perturbations occurred while the seawater sulfate reservoir only had between 10 and 25% of the modern marine sulfate inventory. Furthermore, results from the current study suggest that variations in ocean dissolved oxygen levels, inferred from the δ34S and REE data, are not consistently correlated with nektonic faunal changes during the Olenekian in the studied sections. As such, faunal turnover during the Olenekian is unlikely to be explained exclusively by abiotic factors such as ocean-atmosphere oxygenation levels.

Sulfur assimilation using gaseous carbonyl sulfide by the soil fungus Trichoderma harzianum.

Fungi have the capacity to assimilate a diverse range of both inorganic and organic sulfur compounds. It has been recognized that all sulfur sources taken up by fungi are in soluble forms. In this study, we present evidence that fungi can utilize gaseous carbonyl sulfide (COS) for the assimilation of a sulfur compound. We found that the filamentous fungus Trichoderma harzianum strain THIF08, which has constitutively high COS-degrading activity, was able to grow with COS as the sole sulfur source. Cultivation with 34S-labeled COS revealed that sulfur atom from COS was incorporated into intracellular metabolites such as glutathione and ergothioneine. COS degradation by strain THIF08, in which as much of the moisture derived from the agar medium as possible was removed, indicated that gaseous COS was taken up directly into the cell. Escherichia coli transformed with a COS hydrolase (COSase) gene, which is clade D of the β-class carbonic anhydrase subfamily enzyme with high specificity for COS but low activity for CO2 hydration, showed that the COSase is involved in COS assimilation. Comparison of sulfur metabolites of strain THIF08 revealed a higher relative abundance of reduced sulfur compounds under the COS-supplemented condition than the sulfate-supplemented condition, suggesting that sulfur assimilation is more energetically efficient with COS than with sulfate because there is no redox change of sulfur. Phylogenetic analysis of the genes encoding COSase, which are distributed in a wide range of fungal taxa, suggests that the common ancestor of Ascomycota, Basidiomycota, and Mucoromycota acquired COSase at about 790-670 Ma.IMPORTANCEThe biological assimilation of gaseous CO2 and N2 involves essential processes known as carbon fixation and nitrogen fixation, respectively. In this study, we found that the fungus Trichoderma harzianum strain THIF08 can grow with gaseous carbonyl sulfide (COS), the most abundant and ubiquitous gaseous sulfur compound, as a sulfur source. When the fungus grew in these conditions, COS was assimilated into sulfur metabolites, and the key enzyme of this assimilation process is COS hydrolase (COSase), which specifically degrades COS. Moreover, the pathway was more energy efficient than the typical sulfate assimilation pathway. COSase genes are widely distributed in Ascomycota, Basidiomycota, and Mucoromycota and also occur in some Chytridiomycota, indicating that COS assimilation is widespread in fungi. Phylogenetic analysis of these genes revealed that the acquisition of COSase in filamentous fungi was estimated to have occurred at about 790-670 Ma, around the time that filamentous fungi transitioned to a terrestrial environment.

Mitochondrial-targeted curcumin inhibits T-cell activation via Nrf2 and inhibits graft-versus-host-disease in a mouse model.

Anti-inflammatory and immune suppressive agents are required to moderate hyper-activation of lymphocytes under disease conditions or organ transplantation. However, selective disruption of mitochondrial redox has not been evaluated as a therapeutic strategy for suppression of T-cell-mediated pathologies. Using mitochondrial targeted curcumin (MitoC), we studied the effect of mitochondrial redox modulation on T-cell responses by flow cytometry, transmission electron microscopy, transcriptomics, and proteomics, and the role of Nrf2 was studied using Nrf2- /- mice. MitoC decreased mitochondrial TrxR activity, enhanced mitochondrial ROS (mROS) production, depleted mitochondrial glutathione, and suppressed activation-induced increase in mitochondrial biomass. This led to suppression of T-cell responses and metabolic reprogramming towards Treg differentiation. MitoC induced nuclear translocation and DNA binding of Nrf2, leading to upregulation of Nrf2-dependent genes and proteins. MitoC-mediated changes in mitochondrial redox and modulation of T-cell responses are abolished in Nrf2- /- mice. Restoration of mitochondrial thiols abrogated inhibition of T-cell responses. MitoC suppressed alloantigen-induced lymphoblast formation, inflammatory cytokines, morbidity, and mortality in acute graft-versus-host disease mice. Disruption of mitochondrial thiols but not mROS increase inculcates an Nrf2-dependent immune-suppressive disposition in T cells for the propitious treatment of graft-versus-host disease.

Redox changes and cellular senescence in Alzheimer's disease

The redox process and cellular senescence are involved in a range of essential physiological functions. However, they are also implicated in pathological processes underlying age-related neurodegenerative disorders, including Alzheimer's disease (AD). Elevated levels of reactive oxygen species (ROS) are generated as a result of abnormal accumulation of beta-amyloid peptide (Aβ), tau protein, and heme dyshomeostasis and is further aggravated by mitochondria dysfunction and endoplasmic reticulum (ER) stress. Excessive ROS damages vital cellular components such as proteins, DNA and lipids. Such damage eventually leads to impaired neuronal function and cell death. Heightened oxidative stress can also induce cellular senescence via activation of the senescence-associated secretory phenotype to further exacerbate inflammation and tissue dysfunction. In this review, we focus on how changes in the redox system and cellular senescence contribute to AD and how they are affected by perturbations in heme metabolism and mitochondrial function. While potential therapeutic strategies targeting such changes have received some attention, more research is necessary to bring them into clinical application.

Sequential separation of cerium (Ce) and neodymium (Nd) in geological samples for high-precision analysis of stable Ce isotopes, and stable and radiogenic Nd isotopes by MC-ICP-MS

Stable isotopes of cerium (Ce) and neodymium (Nd), two rare earth elements (REEs), have emerged recently as useful tracers for a range of geological and environmental processes, such as redox changes in environments or continental weathering.

Nitric Oxide Signaling Function in Plant Pathogen Interaction

Nitric oxide (NO) may be a diatomic gaseous atom, which plays distinctive parts completely different strata of life forms. Found as a neurotransmitter in creatures, presently picked up a significant place in plant signaling cascade. NO as a key molecular signal that takes an interest within the direction of a few physiological forms in specific, it features a critical part in plant resistance to pathogens by activating resistance related cell passing and by contributing to the nearby and systemic acceptance of protection qualities. NO invigorates flag transduction pathways through protein kinases, cytosolic Ca2+ mobilization and protein alteration (i.e., nitrosylation). S-nitrosylation can balance the work of target proteins, empowering responsiveness to cellular redox changes [1].

Precise design of copolymer-conjugated nanocatalysts for active electron transfer.

A copolymer-conjugated nanocatalytic system has been designed for active electron transfer. To enhance photoinduced H2 generation, we precisely synthesize ternary random copolymers capable of transferring electrons through phase transitions, extending and shrinking in response to viologen's redox changes within 2 nm distance from the surface of the catalytic nanoparticle.

A growth type pathway for improving the folding of BPTI.

The in vitro oxidative folding of the protein bovine pancreatic trypsin inhibitor (BPTI) with oxidized dithiothreitol or glutathione has served as a paradigm for protein folding but could take weeks at physiological pH because of the need to escape from kinetic traps via a rearrangement type pathway. The two major kinetic traps are called N' and N* and contain two of the three native disulfide bonds, which occur between residues 5 and 55, 30 and 51, and 14 and 38. N' is missing the disulfide bond between residues 5 and 55 while N* is missing the disulfide bond between residues 30 and 51. By determining rate constant for the reactions of the kinetic traps N* and N' and their mixed disulfides with glutathione and glutathione disulfide, many for the first time, we demonstrate that growth type pathways are feasible and could even be more efficient than rearrangement type pathways. Thus, formally unproductive pathways became productive. Interestingly, under physiological redox conditions both rearrangement and growth type pathways are important highlighting the redundancy of oxidative protein folding. With the new set of rate constants, modeling indicated that in vitro oxidative protein folding of BPTI via a growth type pathway using an oxidation, reduction and oxidation cycle would significantly improve protein folding efficiency, albeit under non-physiological redox conditions. With these changing conditions 91 ± 2% of native BPTI was achieved in 12 h compared to 83% native protein in 24 h using our previous best conditions of 5 mM GSSG and 5 mM GSH. Therefore, changing redox conditions via an oxidation, reduction and oxidation cycle may become an additional methodology for enhancing in vitro protein folding in aqueous solution.

Digital Composition Control of Cobalt Nickel Oxides by ALD for the Oxygen Evolution Reaction

Anion exchange membrane water electrolysis is a potentially low-cost and sustainable technology for renewable-energy driven hydrogen production. Realisation of its full potential relies on the development of cost-effective, earth-abundant OER electrocatalysts alternatives to the state-of-the art noble metal oxides1. Ternary transition metal oxides, such as cobalt nickel oxides, are promising candidates due to their excellent alkali resistance in combination with remarkable catalytic activities. The latter relate to their tuneable oxidation states and variation in coordination of their metal centres. These correlations can be properly investigated when precise control over the layer chemical composition is attained. Atomic layer deposition (ALD) is widely acknowledged to deliver control over film uniformity, thickness and conformality, as well as film chemical composition due to the self-limiting nature of its surface reactions.In this study, an ALD supercycle process based on cobalt cyclopentadienyl (CoCp2) and nickel methylcyclopentadienyl (Ni(MeCp)2) precursors and an oxygen plasma co-reactant has been developed2 to investigate the influence of chemical composition and crystallographic properties of cobalt nickel oxide thin films on their electrocatalytic OER performance. Deposition of ~20 nm binary nickel oxide and cobalt oxide results in the growth of polycrystalline films of the rock-salt and spinel phase, respectively. Ternary cobalt nickel oxide films with various ratios can be deposited uniformly, as indicated by energy dispersive x-ray spectroscopy mapping. The mixed oxides display a transition from the +2 oxidation state-based pure rock-salt phase (<25 at.% Co) to the spinel phase consisting of mixed +2/+3 oxidation states (>75% at.% Co) upon increasing Co at.% as verified by electron diffraction (figure a) and x-ray photoelectron spectroscopy (XPS). XPS furthermore reveals a linear increase in the Ni3+-to-Ni2+ ratio with increasing Co at.%, which indicates that an inverse spinel structure is formed. The formation of a Ni3+-rich inverse spinel cobalt nickel oxide between 55 and 75 at.% Co facilitates the formation of a semi-metallic state (102 S/cm) as opposed to the poorly conductive binary oxides (10-3 S/cm and 10-2 S/cm for NiO and Co3O4, respectively).Cyclic voltammetry (CV) measurements in 1M KOH, reveal chemical composition dependent activation behaviour (figure b). Continuous activation behaviour is observed for rock-salt phase films, whilst increment of the Co at.% results in reduced film activation until virtually no activation of the spinel phase films is observed. The activation of the nickel-rich film is accompanied by irreversible redox changes from the +2 to +3 oxidation state as indicated by the integrated non-catalytic wave. Post CV XPS analysis confirms the transition from Co2+ and Ni2+ oxidation states to Co3+ and Ni3+. The formation of an (oxy)hydroxide state is observed for the rock-salt dominated films, whilst oxidation states characteristic of a spinel- like oxide structure are observed for the cobalt-rich films. No changes in the transition metal ratios are observed after activation. Scanning electron microscopy images furthermore reveal that the transformation of the Ni-rich films is accompanied by surface restructuring. These results indicate that initial composition can significantly influence the electrocatalytic performance of ternary oxides and therefore highlight the importance of techniques such as atomic layer deposition to study their complex behaviour. 1Xu et al., Energy Chem., 4 (2022) 100087 2van Limpt et al., J. Vac. Sci. Technol. A, 41 (2023) 032407 This work has been carried out within the SCALE project (NWA.1237.18.001) funded jointly by the Netherlands Organization for Scientific Research. Authors would like to thank the co-founders of the project ISPT, Syngaschem, VecoPrecision and Vsparticle and international partners Toyota Motor Europe and FORTH institute. Figure:(a) ALD deposited cobalt nickel oxide film show a transition from the +2 oxidation state-based rock-salt phase (NiO) to the spinel structure consisting of mixed +2/+3 oxidation states (Co3O4) upon tuning the chemical composition as identified by electron diffraction. (b) This significantly affects the OER-electrocatalytic performance and activation of the films as represented by the current density at 1.8V vs RHE over 500 CV cycles in 1M KOH. Data labels indicate cobalt concentration as at.% Co/(at.% Co+ at.% Ni). Figure 1

Activity and Stability of High-Surface-Area Nickel-Based Catalysts for the Alkaline Hydrogen Evolution Reaction Under Industrially Relevant Conditions

Alkaline water electrolysis (AWE) is at a stage of high technological maturity, and modern pressurized designs have mitigated the weaknesses of now-outdated atmospheric electrolyzers. For instance, pressurized systems now deliver high hydrogen outputs and can efficiently adjust to rapid changes in power loads. These improvements were, in part, made possible through significant reductions to internal ohmic losses coming from improved gas separators, shorter distances between electrodes, and increased operating temperatures.From an industrial point of view, the critical parameter to optimize is the full stack voltage. The stack voltage is tightly bound to the individual cell voltage and can thus be lowered by employing more efficient electrocatalysts. However, reducing the cell voltage by raising the temperature of operation—thereby improving both reaction kinetics and the conductivity of the KOH electrolyte—can be of similar or even higher importance (e.g., ca. 4.5 mV/˚C, Figure 1) [1]. Therefore, stability under operation at elevated temperatures must be considered when evaluating novel hydrogen and oxygen evolution reaction catalysts for AWE. Else, a novel catalyst risks becoming the bottleneck in the pursuit of higher operating temperatures, limiting its applicability for large-scale electrolysis [2]. Many assessments of novel AWE catalysts are still carried out at room temperature in diluted electrolytes and at low current densities [3]. In the harsher conditions of an electrolyzer, catalysts experience higher dissolution rates and are subject to higher mechanical stress from, for instance, the aggressive bubble evolution. This gap hinders the transfer of catalyst developments from academia to industrial research laboratories and, ultimately, to practical applications.In this work, we attempted to narrow that gap by conducting electrochemical measurements under more application-oriented conditions (i.e., 80-120 °C and 8-11 M KOH). We evaluated the HER activity and the robustness of high-surface-area electrodes produced through controlled leaching of bimetallic nickel-based alloys. A parametric study of the overpotential and robustness as a function of electrochemically active surface area was enabled by varying the synthesis parameters of a Raney-type preparation. Direct coupling to renewable energy sources requires the electrolyzer to frequently and rapidly shut off and on. This intermittent operation induces additional stress on the electrodes as the catalysts transition through different redox states, which is often overlooked in AWE electrocatalyst research. To track redox, compositional, and morphological changes, we used ex situ X-ray photoelectron spectroscopy (XPS) and scanning electron microscopy. At the same time, the dissolution and redeposition of ionic species were monitored using inductively coupled plasma mass spectrometry. By matching the characterization data with the evolution of the overpotential until complete deactivation, we gained an understanding of the degradation mechanisms in high-surface-area nickel-based electrodes. These results shed light on the challenges and prospects of this promising class of electrocatalysts for alkaline HER under industrial conditions.Acknowledgement:This work is partly funded by the Innovation Fund Denmark (IFD) under File No. 1044-00162B.

Changes in Colour and Myoglobin Oxidation in Chicken Meat as Affected by Antioxidants during Storage

The study aimed to investigate the effect of natural antioxidants derived from plants on the changes of colour, pH and myoglobin oxidation of chicken meat during storage. Samples of breast and thighs were divided in three groups – control (C), and treated with infusion of wild basil (T1) or oregano (T2). The meat was stored at 4 °C for 7 days and then at –20 °C up to day 90. The pH, colour, oxymyoglobin (OMb) and metmyoglobin (MetMb) were measured at 0 d, 7 d and 90 d. The antioxidant treatment affected the colour parameters of the chicken meat, as the effect differed according to the muscles and duration of storage. Contrary to breast that exhibited initially decreased yellowness (b*), in T1, the antioxidant treated thigh meat had increased lightness (L*) at 7 d and 90 d, increased b* at 0 d and decreased redness (a*) at 7 d. Duration of storage affected both breast and thigh meat colour, more visible in T1 and T2. Considerable increase in b* was observed in breast, while in thigh meat storage was associated with higher L* and lower a*. Both breast and thigh of the treated groups showed decrease in pH, particularly in the initial stages of storage. The percentage of OMb and MetMb in meat was less affected by the antioxidants. Their effect was stronger in breast, with lower OMb in T1 at the 90th day of storage. Furthermore, this group exhibited dramatic decrease in the OMb in the course of storage. MetMb increased in C and T1 during the storage period. The changes in the myoglobin redox forms in thigh meat are mainly due to storage and are similar to those observed in breast.