Zeocin is a member of the bleomycin family of antibiotics, compounds prized in molecular biology for their ability to cut DNA but feared for their toxicity. The drug mimics the effects of ionizing radiation, inducing both single- and double-strand breaks in the genetic material as well as base substitutions in the DNA molecule. Earlier work has also linked Zeocin to pro-oxidative, mutagenic and carcinogenic effects in yeast, making it an ideal probe for studying how cells cope with one of the most dangerous classes of chemical insults. Understanding precisely how such compounds injure cells — and which cellular states confer protection — matters far beyond the laboratory, because pharmaceutical residues released into the environment can interact with biological targets at very low concentrations and inflict lasting damage on lipids, proteins and DNA.

The research team, working with the widely used laboratory strain S. cerevisiae BY4741, took the unusual step of comparing three distinct cell populations side by side. The first consisted of logarithmically growing cells, the fast-dividing workhorses of most yeast experiments. The second and third came from stationary-phase cultures that had been starved into dormancy for 168 hours: using a Percoll density gradient, the scientists separated these cultures into true quiescent cells, which retain the capacity to re-enter the cell cycle, and non-quiescent cells, a more damaged fraction that has largely lost the ability to reproduce. Because quiescence is thought to be the most common cellular state found on Earth, the authors argue that testing drugs on resting cells may yield far more realistic predictions of how environmental toxicants affect natural microbial communities than the standard practice of testing only on proliferating cultures.

The experiments focused on a battery of molecular sensors of oxidative stress. Cells were exposed to 50 micrograms per millilitre of Zeocin — a concentration corresponding to the IC50, the dose that halves survival — for one hour, after which the researchers measured intracellular reactive oxygen species, carbonylated proteins, oxidized lipids and total glutathione. Reactive oxygen species, the toxic radicals generated when cellular redox balance collapses, rose in all three populations, but not equally. Proliferating cells and non-quiescent cells each accumulated roughly four times more ROS than their untreated counterparts, while quiescent cells showed only a modest 1.5-fold increase, the smallest response of any group.

Damage to macromolecules told a complementary story. Carbonyl groups, the chemical fingerprints of oxidized proteins, increased about threefold in quiescent cells after Zeocin treatment, whereas logarithmic and non-quiescent cells showed only slight elevations. The authors interpret this paradoxical result as a consequence of the quiescent cells’ very low metabolic rate: with reduced capacity to sequester and degrade damaged molecules, oxidized proteins simply accumulate. Lipid peroxidation, measured as malonaldehyde equivalents, followed a different pattern again, with the highest levels of oxidized lipids appearing in Zeocin-treated proliferating and quiescent cells at 1.88 and 1.4 nanomoles per mole respectively, while non-quiescent cells showed negligible lipid damage whether treated or not. Because lipid peroxidation compromises membrane functionality and permeability, the findings suggest that metabolically active cells, with dynamic transport across their membranes, are simply more vulnerable to xenobiotic penetration.

Glutathione, the tripeptide that serves as the cell’s first line of non-enzymatic antioxidant defence, rose in every treated population, confirming that Zeocin provokes a coordinated stress response. The magnitude of the response tracked metabolic activity: proliferating cells boosted glutathione biosynthesis roughly 2.5-fold, consistent with their high rates of transcription and translation, while quiescent cells managed only about a 30 percent increase. Non-quiescent cells carried the highest absolute concentrations of the tripeptide, likely reflecting their chronically elevated baseline ROS levels rather than a specific response to the drug.

The most striking results concerned DNA. Using constant field gel electrophoresis, which quantifies double-strand breaks as the fraction of DNA released from agarose plugs, the team found that spontaneous break levels depended strongly on growth phase, with non-quiescent cells carrying about 1.5 times more spontaneous breaks than either logarithmic or quiescent cells — an expected consequence of their genomic instability and tendency toward apoptosis. When the researchers then challenged cells with much higher Zeocin concentrations, from 100 to 300 micrograms per millilitre, logarithmic and non-quiescent cells responded with statistically significant induction of double-strand breaks, while quiescent cells showed no significant break induction at any concentration tested. Their DNA remained essentially as intact as that of untreated controls.

Repair capacity added a final layer to the picture. When given 30 and 60 minutes to recover after treatment, logarithmic cells demonstrated the best repair performance, with calculated repair capacity rising to 3.21 at the highest Zeocin dose after an hour of recovery. Non-quiescent cells, by contrast, proved unable to repair the induced breaks at all, with repair capacity values hovering near or below 1 regardless of dose or recovery time. For quiescent cells, repair capacity could not even be calculated, simply because the treatment had failed to produce a statistically significant increase in breaks in the first place. The authors attribute the extraordinary resilience of quiescent cells to their distinctive physiology: thickened cell walls, highly condensed chromosomes and increased thermo- and osmotolerance, features that likely restrict Zeocin’s ability to penetrate the cell and reach its DNA target.

Taken together, the study delivers a clear message for toxicology: the physiological state of a cell is a critical determinant of its resistance to environmental stress. Actively proliferating yeast, with their high metabolic activity, elevated baseline ROS and dynamic membranes, proved the most susceptible to Zeocin’s combined assault on DNA, proteins and lipids, while cells that had entered the G0 quiescent state emerged as the most robust. Because S. cerevisiae shares a high degree of genetic conservation with higher eukaryotes and is currently the only experimental system that permits simultaneous in vivo evaluation of all cellular targets, the findings carry implications well beyond microbiology. They suggest that toxicity screening programmes relying exclusively on dividing cells may systematically overestimate — or in some cases mischaracterize — the hazards that drugs and environmental pollutants pose to the dormant microbial populations that dominate natural ecosystems. Incorporating quiescent cells into standard yeast-based test panels, the authors argue, would make such assays smarter, more sensitive and far more representative of the biological reality that toxic compounds encounter in the wild.

Subject of Research: Assessing Zeocin-induced oxidative stress and DNA damage in proliferating, quiescent and non-quiescent Saccharomyces cerevisiae cells

Article Title: Saccharomyces cerevisiae yeast cells as a test system for assessing Zeocin toxicity

Article References: Marinovska, P., Todorova, T., Tomova, A., Pisareva, E., Boyadzhiev, K., Dimitrov, M., Parvanova, P., Dimitrova, M., Chankova, S., & Petrova, V. (2022). Saccharomyces cerevisiae yeast cells as a test system for assessing Zeocin toxicity. BioRisk, 17, 105-116. https://doi.org/10.3897/biorisk.17.77227

Image Credits: AI Generated

DOI: 10.3897/biorisk.17.77227

Keywords: Saccharomyces cerevisiae, Zeocin, toxicity testing, quiescent cells, oxidative stress, reactive oxygen species, glutathione, DNA double-strand breaks, lipid peroxidation, radiomimetic antibiotic, yeast model, cellular stress response

The research team, working with the standard laboratory haploid strain BY4741, separated yeast cultures into logarithmically growing (log) cells, quiescent (Q) cells, and non-quiescent (NQ) cells. Quiescent and non-quiescent fractions were isolated from stationary-phase populations grown for 168 hours by layering the biomass on a Percoll density gradient and centrifuging it. The denser lower fraction contained rounded G0 cells with thickened cell walls and no budding — hallmarks of true quiescence — while the upper fraction held a heterogeneous mix of budding, elliptical, and deformed non-quiescent cells. This separation allowed the investigators to interrogate each population independently, an approach that matters because quiescence is believed to function through mechanisms and gene sets shared with mammalian and human cells.

Menadione, chemically 2-methyl-1,4-naphthoquinone, was applied across a concentration range of 1 to 200 micromolar for 60 minutes at 30 degrees Celsius. The researchers then calculated two lethality benchmarks — the doses killing 20 percent (LD20) and 50 percent (LD50) of each population. The contrast was dramatic. Log cells tolerated menadione with an LD20 of 35 micromolar and an LD50 of 199 micromolar. Quiescent cells, by comparison, succumbed at an LD20 of just 0.65 micromolar and an LD50 of only 9 micromolar — roughly a 22-fold difference in the dose required to kill half the population. Survival curves showed a dose-dependent decline in both populations, but the effect was far more pronounced in the quiescent fraction.

To understand whether this heightened susceptibility translated into actual genetic damage, the team employed constant field gel electrophoresis (CFGE), a technique that detects DNA double-strand breaks by quantifying the fraction of DNA released from the wells of a gel. The results confirmed the survival data in a specific and telling way: dose-dependent double-strand break induction appeared only in quiescent cells. After treatment with 150 micromolar menadione, the level of DNA released was 1.5-fold higher than spontaneous levels. In contrast, neither log nor non-quiescent cells showed any measurable increase in double-strand breaks, even at the same concentrations. This selectivity is significant because double-strand breaks are among the most dangerous forms of DNA damage, capable of triggering mutations, chromosomal rearrangements, or cell death if left unrepaired.

The biochemical analysis painted a complementary picture of why quiescent cells fare so poorly. Reactive oxygen species (ROS) levels in quiescent cells rose approximately three-fold above untreated controls after menadione exposure, while the effect on log cells was statistically detectable but biologically negligible. Superoxide dismutase (SOD), a key enzymatic antioxidant that converts superoxide radicals into less harmful species, was also significantly induced in quiescent cells after treatment — another sign that these cells were experiencing genuine oxidative assault. Catalase levels, by contrast, remained unchanged across all populations, suggesting that the hydrogen peroxide-scavenging arm of the antioxidant system was not the primary responder in this scenario.

Interestingly, the actively dividing log cells showed a different pattern of stress markers. Rather than accumulating ROS, they exhibited higher induction of oxidized proteins — measured as carbonyl groups — with approximately a six-fold increase compared to only a two-fold rise in quiescent cells, which already carried around seven-fold higher constitutive carbonyl levels due to starvation. Lipid peroxidation, tracked through malondialdehyde (MDA), the toxic end product of membrane lipid oxidation, also rose about two-fold in log cells after treatment, while remaining similar between control and treated quiescent cells. The researchers suggest that the thicker cell wall of quiescent cells may partially explain this muted lipid peroxidation response.

Glutathione, the tripeptide that serves as a cellular redox buffer and protects against ROS through detoxification mechanisms, told yet another part of the story. Untreated quiescent cells carried three-fold higher glutathione concentrations than log cells, but menadione treatment produced only a modest two-fold rise in the quiescent fraction. In log cells, the same treatment triggered a seven-fold increase in glutathione levels. Critically, the ratio of oxidized to reduced glutathione (GSSG/GSH) remained relatively constant in quiescent cells before and after treatment. The authors interpret this stability as evidence that menadione’s toxicity in these cells operates through its redox-cycling mechanism — generating ROS — rather than through direct conjugation with reduced glutathione, which would have caused a sharp drop in intracellular glutathione as menadione-S-glutathione conjugates formed.

The non-quiescent population added further nuance. These cells carried significantly higher constitutive levels of ROS, oxidized proteins, and MDA than either log or quiescent cells, reflecting their heterogeneous composition and advanced stationary-phase state. Yet after menadione treatment, their ROS levels actually decreased below control values. The researchers attribute this counterintuitive result to a higher percentage of non-quiescent cells being in a terminal state and entering apoptosis, a process that would reduce measurable ROS as cells progressively lose metabolic function.

The mechanistic explanation for quiescent cells’ vulnerability likely lies in their metabolic profile. Quiescent cells are characterized by lower energy consumption and reduced ADP content, conditions that may lead to increased intracellular oxygen levels and a greater prevalence of single-electron oxygen reducers. Because quinones like menadione depend on oxygen presence to catalyze ROS generation through redox cycling, the oxygen-rich, metabolically quiescent environment may amplify the compound’s genotoxic effects. This finding carries broader implications, since most cells in human tissues are non-dividing, making quiescence a major form of cellular life whose stress responses remain understudied in multicellular organisms due to signal complexity.

Taken together, the study establishes that Saccharomyces cerevisiae quiescent cells are the most susceptible population to menadione’s action, and it suggests that the DNA-damaging and genotoxic effects observed in these cells are related to ROS production. Because yeast genes and protein functions are homologous to those of mammals, the results position quiescent yeast as a practical platform for screening the effects of toxic compounds on mammalian and human cells — particularly relevant for understanding how dormant cells in tissues respond to oxidative challenges that dividing cells can more readily withstand.

Subject of Research: Comparative susceptibility and oxidative stress response of logarithmic, quiescent, and non-quiescent Saccharomyces cerevisiae cell populations to menadione

Article Title: Cellular susceptibility and oxidative stress response to menadione of logarithmic, quiescent, and nonquiescent Saccharomyces cerevisiae cell populations

Article References: Marinovska, P. G., Todorova, T. I., Boyadzhiev, K. P., Pisareva, E. I., Tomova, A. A., Parvanova, P. N., Dimitrova, M., Chankova, S. G., & Petrova, V. Y. (2022). Cellular susceptibility and oxidative stress response to menadione of logarithmic, quiescent, and nonquiescent Saccharomyces cerevisiae cell populations. BioRisk, 17, 127-138. https://doi.org/10.3897/biorisk.17.77320

Image Credits: AI Generated

DOI: 10.3897/biorisk.17.77320

Keywords: Saccharomyces cerevisiae, quiescent cells, menadione, oxidative stress, reactive oxygen species, DNA double-strand breaks, glutathione, superoxide dismutase, lipid peroxidation, cell survival, yeast, genotoxicity

The research team, led by Parinaz Mohammadpour with colleagues Hamid Hassanpour and Karim Manda-Hakki from the Department of Horticultural Sciences, worked with the commercial strawberry cultivar Sabrina, a variety prized for its vigor and fruit quality. Their experimental design was deliberately straightforward but rigorous: a factorial completely randomized setup in which plants received either 160 or 200 milliliters of nutrient solution per plant every other day, crossed with foliar glutathione applications at zero, 500, or 1000 micromolar concentrations. The lower fertigation volume imposed the deficit condition, while the higher volume served as the full-fertigation control. This structure allowed the researchers to separate the effects of water limitation from the effects of the antioxidant treatment, and—crucially—to test whether the two interacted.

The results confirmed what deficit-irrigation growers already know from experience: cutting the fertigation volume significantly impaired plant performance. Water and nutrient scarcity constrains photosynthesis, and when the photosynthetic apparatus cannot dissipate absorbed light energy efficiently, electrons leak to oxygen and generate reactive oxygen species. These molecules—superoxide, hydrogen peroxide, and hydroxyl radicals among them—attack membranes, proteins, and DNA. One of the classic fingerprints of this assault is lipid peroxidation, the oxidative degradation of membrane lipids, which is routinely quantified by measuring malondialdehyde, or MDA, a degradation product that accumulates as peroxidation proceeds. In the deficit-treated plants, oxidative damage markers rose and yield-related attributes declined, exactly the pattern the team expected.

Glutathione treatment, however, changed the picture dramatically. When plants were sprayed with the tripeptide, their internal antioxidant machinery responded as if a signal had been sent to stand up the defenses. The activities of four key enzymes rose significantly: superoxide dismutase, which converts superoxide radicals into hydrogen peroxide; catalase, which breaks hydrogen peroxide down into water and oxygen; ascorbate peroxidase, which uses ascorbic acid to neutralize hydrogen peroxide inside the chloroplast and cytosol; and guaiacol peroxidase, a broad-spectrum peroxidase active in the cell wall and vacuole. At the same time, MDA accumulation dropped and polyphenol oxidase activity fell, both indicating that membranes were suffering less peroxidative damage and that oxidative browning reactions were being held in check.

The biochemical consequences extended beyond enzyme activities into the fruit itself. Glutathione application significantly increased total anthocyanin content—the pigments responsible for the deep red color of ripe strawberries and a major component of their nutritional appeal—along with ascorbic acid, the vitamin C that strawberries are famous for delivering. It also boosted DPPH scavenging activity, a laboratory measure of how effectively fruit extracts neutralize a stable synthetic free radical, which serves as a proxy for overall antioxidant capacity in the harvested product. Interestingly, not every antioxidant metric moved: total phenolics, total flavonoids, and FRAP values—another ferric-reducing antioxidant power assay—showed no significant response to glutathione. This selectivity suggests the tripeptide is not simply flooding the plant with generic reducing power but is instead steering specific branches of the phenylpropanoid and redox pathways.

Perhaps the most technically interesting aspect of the study is what the authors describe as concentration-dependent and non-linear effects. There was no single glutathione dose that won across the board. Yield and MDA reduction responded best to 500 micromolar glutathione under full fertigation at 200 milliliters. DPPH scavenging activity peaked at 500 micromolar under the deficit regime at 160 milliliters. Total anthocyanin content reached its maximum at 1000 micromolar under deficit conditions, while ascorbic acid was highest at 1000 micromolar under full fertigation. In other words, the optimal treatment depended on which trait a grower cared about most and how much water was actually available—a nuance that complicates any simple prescription but also opens the door to precision-targeted applications.

This trait-specificity has real implications for how the findings translate to the field. A producer whose priority is maximizing marketable yield under full irrigation would choose a different glutathione regimen than one growing under water restrictions who wants to preserve fruit color and antioxidant content. The non-linear dose response also hints at the underlying biology: glutathione is not merely a passive antioxidant sponge but a redox-active signaling molecule that participates in the glutathione-ascorbate cycle, in S-glutathionylation of proteins, and in the regulation of transcription factors that orchestrate stress responses. At moderate concentrations it appears to prime these systems optimally; at higher concentrations the benefits shift toward specific quality attributes rather than broad physiological performance, suggesting that excess glutathione may perturb the very redox balance it is meant to stabilize.

The study also fills a gap in the literature on redox-active compounds under deficit fertigation. While glutathione has been studied extensively as a stress mitigator in model plants and in a range of crops under drought, salinity, and heavy metal stress, its role specifically under controlled greenhouse fertigation regimes—where water and nutrients are delivered together in precise volumes—had remained insufficiently characterized. Fertigation is the backbone of modern protected agriculture, from soilless strawberry gutters in commercial greenhouses to substrate culture in vertical farming systems, so understanding how antioxidant supplements interact with fertigation volume is directly relevant to the industry’s most common production method.

For growers, the practical takeaway is that a relatively inexpensive, commercially available molecule applied as a foliar spray can preserve both the physiological performance and the nutritional quality of strawberries when water is scarce. For researchers, the study raises questions about the mechanisms driving the non-linear responses—whether they reflect saturation of glutathione transporters, feedback inhibition of glutathione biosynthesis, or shifts in how the plant allocates reducing equivalents between growth and defense. Either way, the work adds strawberries to the growing list of horticultural crops where exogenous glutathione has demonstrated tangible benefits under water-limited conditions, and it provides a quantitative framework—specific concentrations paired with specific fertigation volumes—that future trials can build on.

As climate variability intensifies and competition for freshwater resources grows, strategies that let crops maintain productivity and quality with less water will only become more valuable. This study suggests that one such strategy may be as simple as spraying plants with a molecule they already possess, at the right dose, at the right moment. The strawberry, already one of the world’s most beloved fruits, may owe its resilience in the greenhouses of tomorrow to a tripeptide that has been quietly defending cells since the dawn of aerobic life.

Subject of Research: Plant Biology

Article Title: Exogenous glutathione enhances antioxidant defense, physiological performance and fruit quality of strawberry under deficit fertigation

Article References: Mohammadpour, P., Hassanpour, H., & Manda-Hakki, K. (2026). Exogenous glutathione enhances antioxidant defense, physiological performance and fruit quality of strawberry under deficit fertigation. BMC Plant Biology. https://doi.org/10.1186/s12870-026-10166-9

Image Credits: AI Generated

DOI: 10.1186/s12870-026-10166-9

Keywords: strawberry, glutathione, deficit fertigation, antioxidant enzymes, reactive oxygen species, anthocyanin, ascorbic acid, lipid peroxidation, plant stress, horticulture, BMC Plant Biology, water stress

The research team hand-gathered mussels from sublittoral rocks and other hard substrates at depths of one to six meters, sampling sixteen sites along the coast in June and September across 2017 and 2018. Back in the laboratory, the animals were dissected and three organs were analyzed separately: the gills, the digestive gland and the foot. Each organ was frozen in liquid nitrogen and stored at minus 80 degrees Celsius before being homogenized in potassium phosphate buffer under strictly controlled cold conditions. The team then measured a battery of biochemical indicators spectrophotometrically, including lipid peroxidation, glutathione levels, and the activities of six key antioxidant enzymes: catalase, superoxide dismutase, glutathione peroxidase, glutathione reductase, glucose-6-phosphate dehydrogenase and glutathione-S-transferase.

The logic behind the study rests on a well-established concept in ecotoxicology: oxidative stress. When marine organisms encounter metals, polycyclic aromatic hydrocarbons or the effects of eutrophication, their cells generate reactive oxygen species that can damage lipids, proteins and DNA. In response, a suite of antioxidant enzymes and molecules mobilizes to neutralize these threats. Because this cellular alarm system reacts before damage becomes visible at the level of whole organisms or populations, oxidative stress biomarkers are regarded as an early warning of environmental deterioration. Mussels, as sessile filter-feeders, integrate the chemical history of their surroundings in their tissues, which is why they are increasingly deployed in environmental monitoring and conservation programs worldwide.

The researchers hypothesized that the intensified environmental pressure of summer, driven by a combination of biogenic, abiogenic and anthropogenic factors, would weaken the antioxidant protection of mussels by the beginning of autumn. What they actually found was far more nuanced. The response of the mussels proved to be highly specific to the organ examined and to the type of biomarker measured, and the seasonal patterns frequently ran in opposite directions at northern versus southern locations along the coast.

Lipid peroxidation, a classic marker of oxidative damage to cell membranes, showed remarkably few seasonal differences overall. The sole significant exception came from mussels collected near the quay on the western side of St. Ivan Island, where September samples displayed higher lipid peroxidation than June samples. The authors attribute this anomaly to intense boat traffic or a momentary pollution event at that particular spot, a reminder that local human activity can leave a biochemical fingerprint even when the broader seasonal picture remains stable.

The clearest seasonal signals emerged in the glutathione system. Glutathione is a small but abundant cellular molecule capable of neutralizing a wide range of reactive oxygen species, including singlet oxygen, hydroxyl radicals, superoxide and hydrogen peroxide, and it also serves as a co-substrate for the enzymes glutathione peroxidase and glutathione-S-transferase. In the digestive gland, glutathione concentrations were significantly higher in autumn samples at almost every location, with exceptions only at Kavarna in the north and at Sozopol port and the Sozopol coastal rocks in the south. Meanwhile, glutathione-S-transferase activity, which participates in binding xenobiotic compounds, rose significantly in autumn across the foot tissue of mussels from all coastal locations and in the gills and digestive gland of mussels from all southern sites. The researchers suggest this autumn surge reflects the cumulative pollution pressure of the summer tourist season, when intensified visitor flows and municipal wastewater discharges activate the detoxification machinery of the mussels.

Glutathione peroxidase told an even more revealing story of geographic divergence. In mussels from all northern locations, the activity of this enzyme in September was significantly lower than in June, in the gills and digestive gland alike, while in mussels from the southern locations the opposite pattern held, with autumn activity generally exceeding summer levels. Glutathione reductase followed a similar split: foot tissue from northern mussels showed significantly increased activity in September, whereas southern mussels displayed a significant autumn decrease in both gills and digestive gland. Glucose-6-phosphate dehydrogenase, which supplies the reducing power that keeps glutathione in its active form, dropped significantly in the gills and digestive gland of all northern September samples but showed no significant seasonal change in southern animals. The authors propose that these opposing north-south trajectories may stem from multiple stressor effects, including the pollutant inflow carried by the Danube River into the northwestern Black Sea.

Superoxide dismutase and catalase, the front-line enzymes that dismantle superoxide radicals and hydrogen peroxide respectively, showed more restrained seasonal behavior. Superoxide dismutase activity remained largely stable between seasons in the foot and gills, with a single exception at cape Chervenka, but the digestive gland told a different tale: all northern locations showed significant seasonal differences in this organ, while in the south only the mussels from St. Ivan Island west and the Sozopol coastal rocks did. Catalase activity in the foot declined from June to September at five locations spanning both regions, yet in the digestive gland of southern mussels the enzyme actually rose in September, while northern digestive glands showed no seasonal shift at all. The digestive gland, which constantly receives substances from the environment including various xenobiotics, proved to be the most responsive organ overall, with statistically significant seasonal differences present in every biomarker measured there.

To make sense of this dense matrix of measurements, the team applied multidimensional scaling, a statistical technique that projects complex multivariate data onto an interpretable two-dimensional plane. The analysis confirmed what the raw numbers suggested: mussels from the northern locations clustered separately from those in the south along the first dimension, demonstrating genuine dissimilarities in pro/antioxidant status between the two coastal regions. Along the second dimension, samples with elevated glutathione and related detoxification enzymes grouped apart from samples characterized by higher lipid peroxidation and activated catalase, indicating distinct physiological states of antioxidant mobilization versus oxidative damage.

The study’s authors conclude that the mussel’s reaction to seasonal abiotic, biotic and anthropogenic stress factors is specific to the target organ and the type of biomarker, and that the animals continuously respond to local fluctuations in temperature, hypoxia, the hydrological cycle and their own metabolic condition. For the growing field of biomonitoring, the message is clear: a single-season, single-organ snapshot risks misreading the health of a coastal ecosystem. Seasonal baselines must be established for each locality before oxidative stress biomarkers can be interpreted with confidence. The researchers emphasize that further work is needed to confirm these findings and to build a complete picture of seasonal and spatial variation in the antioxidant defenses of Bulgarian Black Sea mussels, so that this hardy filter-feeder can serve as a reliable sentinel for one of Europe’s most environmentally pressured semi-enclosed seas.

Subject of Research: Seasonal variation in oxidative stress biomarkers of mussels from Bulgarian Black Sea coastal habitats

Article Title: Seasonal changes in the pro/antioxidant status of mussels Mytilus galloprovincialis (Lamarck, 1819) from Bulgarian Black Sea coastal habitats

Article References: Tsvetanova, E., Georgieva, A., Chipev, N., & Alexandrova, A. (2022). Seasonal changes in the pro/antioxidant status of mussels Mytilus galloprovincialis (Lamarck, 1819) from Bulgarian Black Sea coastal habitats. BioRisk, 17, 241-251. https://doi.org/10.3897/biorisk.17.77279

Image Credits: AI Generated

DOI: 10.3897/biorisk.17.77279

Keywords: Mytilus galloprovincialis, oxidative stress, antioxidant enzymes, Black Sea, biomonitoring, glutathione, lipid peroxidation, marine bivalves, environmental monitoring, Bulgarian coast, digestive gland, seasonal variation

BRD4, or bromodomain-containing protein 4, is a transcriptional co-regulator that has attracted intense interest in cancer research because it helps orchestrate which genes are switched on and how actively they are read. What makes the new work distinctive is its focus on isoforms, the different protein variants produced from the same gene. The BRD4 gene can generate at least two major products, a long form known as BRD4-L and a short form known as BRD4-S. These variants are not interchangeable duplicates. The research team set out to determine whether they play distinct roles in gastric cancer biology, and their answer was unambiguous: only the short form, BRD4-S, behaved as a driver of aggressive disease.

Using isoform-specific genetic manipulation in gastric cancer cell lines, the investigators showed that BRD4-S, but not BRD4-L, promoted cell proliferation and invasion. When the team examined tumor samples from patients, high BRD4-S expression tracked with unfavorable clinical outcomes, marking it as a potential biomarker of poor prognosis. That observation alone would have been noteworthy, but the real surprise came when the researchers asked what happens to gastric cancer cells when BRD4-S is removed. The cells did not simply slow down. They became dramatically more vulnerable to ferroptosis, an iron-dependent form of regulated cell death driven by the accumulation of lipid peroxides in cellular membranes.

Ferroptosis has emerged over the past decade as a promising therapeutic angle in oncology because many cancer cells, by virtue of their altered metabolism, sit close to the threshold of this oxidative form of death. The cell’s main defense against it is glutathione, a small tripeptide antioxidant that the enzyme glutathione peroxidase 4 uses to neutralize lipid peroxides. Deplete glutathione and the membranes begin to oxidize uncontrollably. When Liang and colleagues depleted BRD4-S in gastric cancer cells, they observed precisely this cascade: intracellular glutathione levels fell, lipid peroxidation rose, and the cells succumbed far more readily to ferroptotic triggers.

The mechanistic heart of the paper lies in how BRD4-S maintains the glutathione supply line. Through co-immunoprecipitation experiments, the team found that BRD4-S physically interacts with YY1, a well-known transcription factor, and that this partnership facilitates YY1’s occupancy at the promoters of two genes: PCK2, which encodes phosphoenolpyruvate carboxykinase 2, and SLC7A11, which encodes the light chain of the cystine-glutamate antiporter that imports cystine, the raw material for glutathione synthesis. Chromatin immunoprecipitation confirmed that BRD4-S loss reduced YY1 binding at these regulatory regions, and with it, expression of both genes.

Each of those two genes contributes a distinct piece of the antioxidant puzzle. SLC7A11 supports the uptake of cystine from the extracellular environment, providing the limiting building block for glutathione. PCK2, an enzyme better known for its role in gluconeogenesis within mitochondria, was shown here to steer glutamine metabolism toward glutathione production. The researchers demonstrated this using carbon-13 and nitrogen-15 labeled glutamine tracing, a technique that allows biochemists to follow the fate of individual atoms as they flow through metabolic networks. Together, PCK2 and SLC7A11 form a two-pronged program that keeps glutathione homeostasis intact and lipid peroxidation in check.

The functional importance of this program was confirmed by rescue experiments. When the team restored PCK2 and SLC7A11 expression in cells lacking BRD4-S, the ferroptotic phenotype partially reversed: glutathione recovered, lipid peroxidation subsided, and the cells regained their resistance. The same restoration blunted the increased sensitivity to oxaliplatin, a platinum-based chemotherapy drug commonly used in neoadjuvant regimens for gastric cancer. Critically, these rescue effects held not only in cultured cells but also in animal models, where re-expression of the two metabolic genes partially restored tumor growth and drug resistance in vivo.

The link to oxaliplatin is where the study acquires its most direct clinical relevance. Oxaliplatin’s cytotoxicity is intertwined with oxidative stress, and tumors with robust antioxidant capacity tend to withstand it better. Because BRD4-S sustains the glutathione buffer, high BRD4-S tumors are effectively pre-armored against the oxidative component of the drug’s action. The clinical data bore this out: among gastric cancer patients treated with oxaliplatin-based neoadjuvant chemotherapy, those with lower BRD4-S expression in their tumors showed a higher rate of major pathological response and reached a more favorable post-treatment pathological stage. In other words, BRD4-S levels in the pretreatment tumor appeared to predict how well the chemotherapy would work.

These findings carry several implications for the field. First, they underscore that BRD4 isoforms must be studied separately; lumping them together in pan-BRD4 assays or pan-BRD4 inhibitors may obscure the specific contribution of the short form. Second, they position ferroptosis sensitivity as a tunable property of gastric cancer cells, one that can be dialed down by a single transcriptional regulator acting through YY1. Third, they suggest a potential therapeutic window: combining oxaliplatin with strategies that suppress BRD4-S, disrupt its interaction with YY1, or otherwise deplete glutathione defenses could sensitize otherwise resistant tumors. The authors frame BRD4-S as a potential therapeutic vulnerability, and the rescue data provide a mechanistic rationale for that framing.

As with any laboratory and clinical-correlate study, important questions remain before this biology can be translated into the clinic. The work was conducted with cell lines, animal models, and patient cohorts from a single institution, and prospective validation in larger, independent patient populations will be needed to establish BRD4-S as a predictive biomarker for oxaliplatin response. Whether pharmacological tools can selectively target BRD4-S without disturbing the long isoform is another open challenge, since isoform-selective inhibition remains technically demanding. Nevertheless, the study adds a compelling new node to the growing map connecting epigenetic regulators, glutamine metabolism, and ferroptosis in cancer, and it offers gastric cancer patients and their physicians a measurable molecular feature that may help forecast who will benefit from one of the standard weapons against this disease.

Subject of Research: BRD4-S regulation of glutathione metabolism, ferroptosis resistance, and oxaliplatin response in gastric cancer

Article Title: BRD4-S reprograms glutathione metabolism to reduce ferroptosis sensitivity and limits oxaliplatin response in gastric cancer

Article References: Liang, Y., Wei, M., Yan, Z., Sun, G., Zhao, H., Sun, D., Yang, W., Cheng, Z., Wang, H., Wu, S.-Y., Chiang, C.-M., Cui, X., & Yu, W. (2026). BRD4-S reprograms glutathione metabolism to reduce ferroptosis sensitivity and limits oxaliplatin response in gastric cancer. Journal of Experimental & Clinical Cancer Research. https://doi.org/10.1186/s13046-026-03855-8

Image Credits: AI Generated

DOI: 10.1186/s13046-026-03855-8

Keywords: gastric cancer, BRD4-S, ferroptosis, glutathione, PCK2, SLC7A11, YY1, oxaliplatin, cancer metabolism, chemotherapy response, lipid peroxidation, transcriptional regulation

The review, led by Nooneh Khachatourian, Rubina Takhmazian, and Vishwanath Venketaraman, builds on a well-established epidemiological foundation. Undernutrition is already recognized as one of the most significant modifiable risk factors for tuberculosis, with more than one-fifth of global TB cases estimated to be attributable to it. Systematic reviews have shown that undernutrition substantially increases the risk of developing active TB and that malnutrition is associated with worse treatment outcomes, including treatment failure, loss to follow-up, and death. But the relationship runs both ways: TB itself drives nutritional deterioration through chronic inflammation, increased metabolic demands, reduced appetite, and impaired nutrient utilization. What the authors add to this picture is a third player—the thyroid gland—whose hormone output depends critically on the very micronutrients that malnutrition depletes and whose hormones, in turn, help regulate the immune cells that fight M. tuberculosis.

Thyroid hormones, triiodothyronine (T3) and thyroxine (T4), are best known for regulating metabolism, energy expenditure, lipid profiles, glucose utilization, thermogenesis, and body weight. But an accumulating body of experimental evidence shows that they also act directly on the immune system. Macrophages, dendritic cells, neutrophils, and T lymphocytes all express thyroid hormone receptors and respond to thyroid hormone signaling. Experimental studies indicate that these hormones regulate neutrophil respiratory burst activity, reactive oxygen species production, macrophage phagocytic capacity, cytokine signaling, and inflammatory responses. Thyroid hormone receptor α signaling has also been implicated in T-cell activation and in the function of regulatory T cells, which temper pro-inflammatory responses and enhance anti-inflammatory regulation. Because many of these same pathways are central to controlling intracellular pathogens such as M. tuberculosis, the authors propose that hypothyroidism—an extremely common endocrine disorder worldwide—may represent an underrecognized factor compromising antimicrobial defense.

The bridge between nutrition and thyroid function is built from specific micronutrients. Iodine is the structural backbone of both T3 and T4; the body cannot synthesize it, so dietary intake is indispensable. Although iodization programs have reduced severe deficiency, roughly 30 percent of the world’s population remains at risk of inadequate iodine intake, which impairs hormone synthesis and leads to compensatory thyroid enlargement and hypothyroidism. Selenium is equally critical: the thyroid contains the highest concentration of selenium per gram of tissue of any organ in the human body, reflecting the role of selenium-dependent iodothyronine deiodinases (DIO1, DIO2, and DIO3) that convert the prohormone T4 into biologically active T3. Selenium-dependent glutathione peroxidases and thioredoxin reductases also protect thyroid tissue from the oxidative damage generated during hormone biosynthesis, a process that inherently requires hydrogen peroxide as a substrate for thyroid peroxidase-mediated iodination. Selenium deficiency therefore impairs hormone activation, increases oxidative stress, and is associated with autoimmune thyroid disease.

Iron, the most prevalent micronutrient deficiency worldwide, adds another layer. Thyroid peroxidase, the enzyme responsible for iodide oxidation and organification, is heme-dependent and requires adequate iron availability for optimal catalytic activity. A recent systematic review and meta-analysis found significantly lower free T3 and free T4 concentrations among iron-deficient individuals compared with healthy controls. Iron deficiency frequently coexists with chronic inflammation, malnutrition, and infectious disease, which the authors suggest makes its impact on thyroid physiology particularly relevant in populations at elevated TB risk. Zinc contributes through zinc-finger transcription factors and thyroid hormone receptor signaling, with deficiency linked to impaired hormone metabolism and immune dysfunction. Vitamin D, meanwhile, exerts immunomodulatory effects through regulation of T-cell differentiation, cytokine production, and immune tolerance, and observational studies consistently report lower circulating vitamin D concentrations in patients with hypothyroidism, Hashimoto’s thyroiditis, and autoimmune thyroid disease compared with healthy controls.

The immunological case for why thyroid dysfunction might matter in TB rests on the biology of host defense. After inhalation, resident alveolar macrophages constitute the first line of defense, and successful containment of M. tuberculosis requires efficient macrophage activation, granuloma formation, robust T-cell responses, tightly regulated cytokine networks, and control of oxidative stress. Experimental studies show that thyroid hormones regulate macrophage survival and phagocytic activity, influence the production of reactive oxygen species, and modulate the expression of genes involved in antimicrobial responses. On the adaptive side, control of M. tuberculosis depends largely on CD4-positive T lymphocytes generating type 1 helper (Th1) responses characterized by interferon-γ and tumor necrosis factor-α—cytokines that activate infected macrophages and maintain granulomas. Thyroid hormones influence T-cell development, differentiation, and activation through receptor-mediated signaling, so dysregulation of these pathways could plausibly weaken the Th1 response that keeps mycobacteria in check.

Evidence from autoimmune thyroid disease reinforces how closely thyroid function and immune regulation are intertwined. Conditions such as Hashimoto’s thyroiditis and Graves’ disease feature lymphocytic infiltration, loss of immune tolerance, abnormal helper T-cell responses, and chronic cytokine-mediated inflammation, with increased expression of the chemokines CXCL9, CXCL10, and CXCL11 recruiting Th1 lymphocytes into thyroid tissue. Impaired suppressive activity of regulatory T cells has also been reported in autoimmune thyroid disease, and because balanced Treg responses are important for limiting immunopathology during TB infection, such disturbances may further influence susceptibility and disease progression. Beyond direct immune effects, chronic hypothyroidism is associated with low-grade systemic inflammation and altered immune cell metabolism, and thyroid hormones regulate the mitochondrial function, glucose utilization, and lipid metabolism that underpin the energetic demands of immune activation—processes increasingly recognized as determinants of TB outcomes.

The epidemiological spark for this framework comes from an 18-year nationwide population-based longitudinal cohort study, which found that individuals with hypothyroidism had an increased risk of subsequently developing TB, while patients with TB also had an elevated risk of subsequent hypothyroidism. The authors are careful to note that this observational association cannot establish causality and may be confounded by nutritional status, comorbidities, socioeconomic conditions, chronic inflammation, and medication exposure. The relationship is also bidirectional in a treatment context: antitubercular agents including ethionamide, prothionamide, and para-aminosalicylic acid inhibit thyroid peroxidase activity and disrupt iodine organification, producing hypothyroidism in approximately 17 percent of patients receiving treatment for multidrug-resistant TB. Chronic infection itself alters hypothalamic-pituitary-thyroid axis regulation through pro-inflammatory cytokines such as IL-1, IL-6, and TNF-α, meaning TB can both cause and be influenced by endocrine disturbance.

On the intervention side, the review takes a notably sober view of supplementation. Vitamin D is the most extensively studied micronutrient in the TB context because it enhances macrophage antimicrobial activity through induction of cathelicidin, stimulation of autophagy, and promotion of intracellular killing of M. tuberculosis. Yet recent randomized-trial meta-analyses have found no significant reduction in TB infection or progression to active disease with vitamin D supplementation, and limited or inconsistent effects on microbiological treatment outcomes such as sputum smear and culture conversion. The authors argue that evidence supporting correction of a documented deficiency should be distinguished from evidence supporting routine supplementation specifically for TB prevention, and they point to substantial heterogeneity across studies in baseline nutritional status, dose, formulation, duration, and clinical outcomes as a key reason findings have been inconsistent. Similar caution applies to selenium, zinc, and iron: correcting documented deficiencies may support both thyroid and immune function, but evidence that supplementation independently improves TB-specific outcomes remains limited, and excessive intake of certain micronutrients can itself harm endocrine or immune function.

One of the more intriguing therapeutic leads involves glutathione, the body’s principal intracellular antioxidant. Patients with TB frequently exhibit depleted glutathione levels, compromising antioxidant defenses, macrophage function, cytokine regulation, and T-cell-mediated immunity. Experimental and clinical studies suggest that glutathione supplementation may reduce oxidative stress, enhance Th1-associated immune responses, increase production of IFN-γ and TNF-α, and decrease intracellular mycobacterial burden—preliminary but biologically coherent findings, given that glutathione metabolism is closely linked to selenium-dependent antioxidant systems. The authors conclude that the nutritional–endocrine–immune framework they propose is biologically plausible and hypothesis-generating rather than an established causal pathway, and that current evidence does not support routine thyroid screening solely to reduce TB risk. What they call for instead are prospective cohort studies determining whether thyroid dysfunction independently predicts TB after accounting for confounders, adequately powered trials of micronutrient correction in deficient populations, and standardized assessment of nutritional status, thyroid function, and clinical outcomes. If the proposed cycle of malnutrition, thyroid dysfunction, and impaired antimycobacterial immunity holds up under clinical scrutiny, nutritional optimization and early endocrine management could eventually become integrated adjunctive strategies in the fight against one of humanity’s oldest infectious diseases.

Subject of Research: The interplay between nutrition, thyroid function, and immune defense against tuberculosis

Article Title: Nutrition, thyroid function, and tuberculosis: exploring the endocrine–immune axis

Article References: Khachatourian, N., Takhmazian, R., & Venketaraman, V. (2026). Nutrition, thyroid function, and tuberculosis: exploring the endocrine–immune axis. Frontiers in Tuberculosis, 4, Article 1945832. https://doi.org/10.3389/ftubr.2026.1945832

Image Credits: AI Generated

DOI: 10.3389/ftubr.2026.1945832

Keywords: tuberculosis, thyroid hormones, hypothyroidism, micronutrients, iodine, selenium, vitamin D, immune regulation, malnutrition, endocrine-immune axis, glutathione, Mycobacterium tuberculosis

Diabetic retinopathy is a devastating complication of diabetes and a major cause of vision loss in working-age adults. Epidemiological projections cited in the study’s background literature estimate that hundreds of millions of people will be living with the condition by mid-century as global diabetes rates climb. At the tissue level, the disease damages the retina’s delicate vasculature, but growing evidence indicates that the retinal pigment epithelium, a monolayer of support cells that nourishes and maintains the light-sensitive photoreceptors, is an early and critical casualty. When these cells falter, the entire retina suffers. Current treatments, ranging from laser therapy to injections of anti-VEGF drugs, manage symptoms and slow progression but do not halt the underlying cellular degeneration, leaving an urgent need for therapies that act on root causes.

In recent years, one root cause has attracted intense attention: ferroptosis. This form of regulated cell death, formally described only in 2012, differs fundamentally from apoptosis. Rather than quietly dismantling itself, a ferroptotic cell succumbs to an iron-dependent assault on its own membranes. Free iron catalyzes the peroxidation of polyunsaturated lipids in the cell membrane, and once lipid peroxides accumulate beyond a survivable threshold, the membrane ruptures and the cell dies in an inflammatory fashion. Because the retina is rich in both iron and polyunsaturated fatty acids and operates under high oxygen tension, it is uniquely vulnerable to this mode of death. Prior studies, including work by some of the same Kunming group, have linked oxidative stress-induced ferroptosis in retinal pigment epithelial cells to diabetic retinal damage, making the ferroptosis pathway a compelling therapeutic target.

To model diabetic conditions in the laboratory, the team exposed ARPE-19 cells, a widely used human retinal pigment epithelial cell line, to an elevated glucose concentration of 33 millimoles per liter. The consequences were exactly what the ferroptosis hypothesis predicts. Cell viability, measured with a CCK-8 assay, dropped significantly compared with cells grown in normal glucose. Inside the stressed cells, the researchers detected rising levels of ferrous iron and lipid peroxidation, visualized with the fluorescent probe BODIPY-C11, while the cellular reservoir of the antioxidant molecule glutathione, or GSH, shrank. Western blot analysis revealed that two key guardians of the antiferroptotic defense, the proteins GPX4 and SLC7A11, were downregulated. GPX4 is the only mammalian enzyme capable of reducing lipid hydroperoxides directly within membranes, and SLC7A11 is the transporter subunit that imports cystine, the raw material cells need to synthesize glutathione. Suppress both, and the cell loses its main protection against membrane oxidation.

Crucially, the researchers confirmed that ferroptosis was genuinely the mode of death at work. When they treated the high-glucose cells with ferrostatin-1, a classical ferroptosis inhibitor, or with deferoxamine, an iron chelator that starves the Fenton chemistry driving lipid peroxidation, cell viability recovered and lipid peroxidation receded. That pharmacological validation mattered, because it established that rescuing cells from iron-dependent lipid damage was sufficient to counter the glucose insult. Only then did the team introduce acteoside to see whether the natural product could reproduce that protection on its own.

It could. Acteoside intervention markedly reversed the high glucose-induced promotion of ferroptosis, restoring viability and damping the biochemical hallmarks of lipid peroxidation. The compound’s influence extended to the master regulatory layer of cellular antioxidant defense: NRF2. Under normal conditions, NRF2 is held in the cytoplasm by its inhibitor Keap1, but oxidative stress or pharmacological activation liberates it, allowing the transcription factor to migrate into the nucleus and switch on hundreds of cytoprotective genes, including those governing glutathione synthesis and GPX4 expression. Using immunofluorescence microscopy, the team observed that acteoside significantly promoted NRF2 nuclear translocation in the stressed cells—direct visual evidence that the compound was turning the pathway on.

The most decisive experiment came next. When the researchers silenced NRF2, acteoside’s protective grip loosened: the compound’s ability to inhibit ferroptosis was significantly weakened in cells lacking functional NRF2. That loss-of-function result elevates the findings from correlation to mechanistic argument. Acteoside does not merely mop up free radicals as a generic antioxidant; it appears to work substantially by engaging the NRF2 signaling axis, which in turn sustains the GPX4 and SLC7A11-dependent firewall against lipid peroxidation. This mode of action distinguishes pathway activators from simple radical scavengers and aligns with a broader therapeutic strategy, since NRF2 agonism is being pursued for a range of diseases involving oxidative damage and inflammation.

Importantly, the story did not end in the culture dish. The team also established a diabetic retinopathy model in C57BL/6 mice using streptozotocin, a chemical that destroys insulin-producing beta cells and induces diabetes, and treated the animals with different doses of acteoside. The results mirrored the in vitro findings with a clear dose-dependent trend. Mice receiving acteoside showed significantly alleviated retinal tissue damage on hematoxylin and eosin staining, along with reduced levels of ferrous iron in the tissue and diminished abundance of 4-HNE and MDA, two well-established byproducts of lipid peroxidation that serve as molecular fingerprints of ferroptotic stress. Glutathione content rose, and Western blots of retinal tissue showed upregulated expression of NRF2, GPX4, and SLC7A11. In short, the same protective circuitry identified in single cells operated in intact, diabetic retinae.

The study adds to a rapidly growing dossier on acteoside, a molecule also known as verbascoside that has drawn attention for antimicrobial, anti-inflammatory, and immunomodulatory properties. The Kunming group itself had previously shown that acteoside protects retinal ganglion cells in experimental glaucoma through the PI3K/AKT pathway and that it relieves diabetic retinopathy by regulating Müller cell reactivity via TXNIP and Kir4.1 channels. Other laboratories have reported that acteoside inhibits ferroptosis in contexts as diverse as hepatic ischemia-reperfusion injury, doxorubicin-induced cardiotoxicity, and neurodegeneration in a Parkinson’s disease model, in the latter case through Nrf2-mediated mitophagy. The new work extends this pattern to the retinal pigment epithelium in diabetes, and it lands alongside a parallel literature in which other natural NRF2 activators, such as corilagin, resveratrol, and ghrelin, have been shown to suppress ferroptosis in diabetic retinal cells.

For the millions of people at risk of diabetic vision loss, the research offers a genuinely encouraging proof of concept, though the usual caveats apply. The findings come from one human cell line and a chemically induced mouse model, and translating a plant-derived compound into a clinically validated therapy will require pharmacokinetic studies, dosing optimization, safety evaluation, and eventually controlled human trials—steps that often stall at the gap between mouse and patient. Still, the study’s central contribution is clear and technically meaningful: it identifies ferroptosis as a driver of high glucose-induced retinal pigment epithelial injury and demonstrates, with both gain- and loss-of-function evidence, that acteoside counteracts that cell death by activating NRF2 signaling and its downstream glutathione-GPX4 antioxidant machinery. If subsequent work confirms the effect in clinical settings, a humble compound long buried in herbal leaves could become a foundation for protecting the sight of a diabetic generation.

Subject of Research: Acteoside-mediated NRF2 activation protecting retinal pigment epithelial cells from high glucose-induced ferroptosis in diabetic retinopathy

Article Title: Acteoside alleviates high glucose-induced ROS accumulation and ferroptosis in ARPE-19 cells by activating the NRF2 signaling pathway

Article References: Shen, S., Chen, Q., Li, Y., Ma, J., Zhang, Y., Luo, H., Peng, D., & Xi, X. (2026). Acteoside alleviates high glucose-induced ROS accumulation and ferroptosis in ARPE-19 cells by activating the NRF2 signaling pathway. Molecular Biology Reports, 53(1), Article 1558. https://doi.org/10.1007/s11033-026-12608-x

Image Credits: AI Generated

DOI: 10.1007/s11033-026-12608-x

Keywords: diabetic retinopathy, acteoside, ferroptosis, NRF2, retinal pigment epithelium, lipid peroxidation, GPX4, SLC7A11, oxidative stress, ARPE-19 cells, glutathione, natural products

The authors, drawing on the clinical staging framework developed by Patrick McGorry and the neuroprogression framework articulated by Michael Berk, assemble a model in which redox compromise sits at the base of a self-reinforcing loop. Redox compromise, in this usage, refers to a chronic state of oxidative stress in which the production of reactive molecules outpaces the brain’s antioxidant defenses, most notably the depletion of glutathione, the nervous system’s principal endogenous antioxidant. That depletion is coupled to mitochondrial inefficiency, meaning that the cellular power plants which neurons depend on generate energy poorly and leak more damaging byproducts in the process, and to the inflammatory state that accompanies both. The result is a nervous system operating under sustained oxidative strain from an early point in the illness.

According to the proposed model, this redox strain feeds forward into a chain of downstream changes. It contributes to NMDA receptor hypofunction, a weakening of signaling through a class of glutamate receptors that are central to synaptic plasticity and to the coordination of neural circuits. Impaired NMDA signaling in turn compromises parvalbumin interneurons, the fast-spiking inhibitory cells that generate the gamma-band rhythms needed for coherent communication across brain regions. Disrupted interneuron function disturbs circuit connectivity, and this disconnection ultimately produces the dopaminergic phenotype—the altered dopamine signaling—that current antipsychotic drugs are built to suppress. The dopamine changes, in this framing, are the downstream face of the illness rather than its origin.

A crucial feature of the hypothesis is its deliberate symmetry. The authors are explicit that they are not claiming redox compromise comes first in every case. Animal studies show that blocking NMDA receptors pharmacologically itself generates oxidative stress, which means the loop runs in both directions and any element within it can initiate or amplify the others. What distinguishes redox compromise, in their argument, is not causal priority but clinical accessibility: unlike genetic risk or early neurodevelopment that cannot be revisited, oxidative stress, glutathione levels and mitochondrial function can be measured in living patients and modified with existing or near-existing interventions, potentially before the circuit changes that current treatment cannot reverse have taken hold.

The staging architecture translates this biology into intervention windows. In the McGorry framework, the earliest levels are treated here as risk strata rather than established disease stages, a distinction the authors stress because labeling at-risk individuals as ill carries its own harms. The clinical high-risk state, in which young people show attenuated psychotic symptoms and other warning signs, becomes the first window in which redox measures could guide who receives preventive care. Later windows correspond to first-episode psychosis and to the chronic phase, with the expectation that the modifiability of the underlying process narrows as neuroprogression advances.

One of the more striking pieces of supporting evidence comes from metabolism. Impaired glucose tolerance has been documented in first-episode patients who have never taken antipsychotics, a finding that neither the medications nor the chronicity of illness can explain. The authors present this as evidence that metabolic disturbance is a parallel expression of the same systemic process that drives oxidative stress in the brain, rather than a side effect of treatment. If the redox-metabolic-inflammatory state is systemic from the illness’s earliest clinical expression, then metabolic measures in antipsychotic-naive patients become another early, modifiable handle on the disease process.

The paper does not shy away from the counterevidence that contests its progressive framing. Antipsychotic exposure itself contributes to brain volume loss, which complicates any simple reading of progressive brain changes as the natural course of the illness. Cognitive impairment, often cited as evidence of neuroprogression, follows a largely stable course after onset rather than a steadily deteriorating one. The authors set these objections out together with the results that would require abandoning the framework entirely, a level of falsifiability that is unusual in hypothesis papers. The human evidence, they conclude, currently supports association and biological plausibility rather than a proven causal direction.

To make the framework testable, the authors organize the biomarker literature by stage and propose three specific predictions that a trial could refute. First, that biomarker-stratified prevention will outperform unselected prevention at the clinical high-risk stage, meaning that using redox measures to decide who receives intervention will beat offering the same intervention to everyone. Second, that two particular measures—glutathione concentrations in the medial prefrontal cortex, measurable with magnetic resonance spectroscopy, and deficits in mismatch negativity, an event-related brain potential that indexes the brain’s automatic prediction error response—will add predictive value beyond clinical assessment alone. Third, that removing the redox measures from a multimodal biomarker panel will worsen its prediction of transition to psychosis, a direct test of whether the redox component carries unique information.

The proposed test is concrete: a biomarker-stratified phase 2b trial with a formal power calculation, in which high-risk individuals are assigned to preventive intervention based on their biomarker profile rather than their clinical presentation alone. Such a trial would move the redox hypothesis from association to intervention, and its design anticipates refutation at every level. If the stratified approach fails, if the two candidate biomarkers add nothing beyond clinical assessment, or if the redox measures prove dispensable within a broader panel, the framework would need revision or abandonment.

The significance of the proposal lies in what it could change about the timing of care. Antipsychotics address the dopaminergic endpoint of the cascade and, in doing so, leave the cognitive and negative symptoms that most burden patients without an effective treatment. If redox compromise can indeed be measured and modified early, interventions aimed at restoring glutathione, improving mitochondrial function and calming inflammation could enter the care pathway at the high-risk stage, before circuit disconnection consolidates. The authors are careful to frame their account as a hypothesis rather than an established account, and the burden of proof now rests with the trial they propose. But the argument reframes schizophrenia’s familiar biology in a way that makes the earliest phase of the illness, for the first time in the dopamine era, a plausible target for prevention.

Subject of Research: Redox compromise as an early, modifiable entry point in schizophrenia and a staging framework for early intervention

Article Title: Redox compromise as an early, modifiable entry point in schizophrenia: a staging framework for early intervention

Article References: Lado, L. A., & Misir, A. (2026). Redox compromise as an early, modifiable entry point in schizophrenia: a staging framework for early intervention. Frontiers in Neuroscience, 20, Article 1941148. https://doi.org/10.3389/fnins.2026.1941148

Image Credits: AI Generated

DOI: 10.3389/fnins.2026.1941148

Keywords: schizophrenia, oxidative stress, glutathione, NMDA receptor hypofunction, parvalbumin interneurons, clinical staging, biomarkers, mismatch negativity, medial prefrontal cortex, neuroprogression, early intervention, dopamine

The diagnostic component of the study is a striking demonstration of how much the choice of test matters. Of 138 samples screened from dogs with suspected babesiosis, the rapid antibody test detected 43 infections, or 31.15 percent. Microscopic examination of blood smears, still the workhorse of parasitology in many clinics, found 70 positive cases, or 50.72 percent. But polymerase chain reaction, the molecular gold standard, confirmed 85 infections, or 61.59 percent of the cohort. The gap between the smear and PCR results is not academic; it means that in a substantial fraction of infected dogs, low-level parasitaemia escapes microscopic detection, allowing animals to remain infectious reservoirs while receiving no treatment. For practitioners in endemic regions, the study’s numbers argue strongly for PCR confirmation whenever clinical suspicion is high but the smear is negative.

Clinically, the infected dogs presented with a constellation of signs that will be familiar to any veterinarian in a Babesia-endemic area. The most consistent findings were depression and lethargy, inappetence or outright anorexia, and pyrexia. These are non-specific complaints, and the study underscores how easily early babesiosis can be mistaken for other febrile illnesses. What elevates the disease’s danger, however, is what happens beneath the surface, where the haematological and biochemical machinery of the body begins to fail in interlocking ways.

The haemogram revealed the classic hallmarks of B. gibsoni infection: anaemia from the destruction of parasitised red cells, thrombocytopaenia reflecting both immune-mediated platelet loss and consumption, and leukocytosis accompanied by neutrophilia and eosinophilia, signatures of a pronounced inflammatory response. On the biochemistry panel, the picture of systemic insult deepened. Dogs showed hypoproteinaemia and hypoalbuminaemia, consistent with protein loss and hepatic dysfunction, alongside hyperbilirubinaemia from red cell breakdown. Azotaemia pointed to renal compromise, while elevated levels of alanine aminotransferase and alkaline phosphatase indicated hepatocellular and cholestatic injury. Serum C-reactive protein, a sensitive acute phase marker, was markedly increased, confirming that the infection triggers a vigorous systemic inflammatory response. Taken together, the authors interpret these changes as evidence of multiple organ dysfunction syndrome, a condition more commonly associated with sepsis than with a haemoprotozoal infection.

Abdominal ultrasonography added an imaging dimension that few studies of this scale have incorporated. The most consistent ultrasonographic finding was splenomegaly, often accompanied by splenic parenchymal lesions, reflecting the spleen’s role as both a graveyard for damaged erythrocytes and a site of intense immunological activity. Perhaps more intriguing was the frequent detection of ascites, with the study noting that B. gibsoni infection is commonly associated with high-gradient ascites, defined by a serum-to-ascites albumin gradient above 1.1 g/dL, and ascitic fluid that was transparent to straw-coloured, characteristic of a transudate. In human medicine, the serum-ascites albumin gradient is a cornerstone of workup for abdominal fluid, distinguishing portal hypertension from inflammatory or malignant causes. Its application here suggests a degree of hepatic circulatory disturbance or hypoalbuminaemia-driven fluid shift that clinicians may be systematically under-recognising in babesiosis cases presenting with a distended abdomen.

The heart of the study, however, lies in its oxidant–antioxidant analysis, which elevates it from a descriptive clinicopathological survey to a mechanistic investigation. The researchers measured lipid peroxides, reduced glutathione, and total antioxidant capacity in the infected dogs and compared them against healthy controls. The results were unambiguous. Dogs with B. gibsoni infection had significantly higher lipid peroxide levels, the chemical fingerprints of free radical attack on cell membranes, and significantly lower concentrations of reduced glutathione and total antioxidant capacity, with all differences reaching statistical significance at P less than 0.001. The antioxidant machinery that normally shields red blood cells from oxidative attack had been overwhelmed.

The correlational analysis transforms this observation into an argument about causation. Red blood cell counts showed a strong negative correlation with lipid peroxide levels, with a correlation coefficient of −0.741 at P less than 0.01, meaning that dogs with the most oxidised red cells also had the fewest circulating red cells. Conversely, RBC counts correlated positively with reduced glutathione (r = 0.714) and total antioxidant capacity (r = 0.828), both at P less than 0.01. The interpretation is straightforward: erythrocyte peroxidation is not merely a bystander effect of infection but appears to be a contributing factor to the severity of the anaemia. When parasite-driven oxidative stress overwhelms the red cell’s enzymatic and non-enzymatic defences, lipid peroxidation renders the membrane rigid and recognisable to macrophages, which then clear the damaged cells, compounding the direct destruction caused by the parasite itself.

This mechanism fits neatly into a broader body of evidence on babesial pathogenesis. Earlier experimental work on B. gibsoni demonstrated enhanced erythrophagocytosis of oxidatively damaged infected erythrocytes and increased superoxide generation within parasitised cells, while studies in other piroplasms, including Babesia bigemina in cattle and ovine malignant theileriosis, have documented the same pattern of oxidant surge and antioxidant depletion. The Mizoram study is significant because it extends these mechanistic insights into a naturally infected, clinically diverse population, and because it ties them quantitatively to the parameter that ultimately matters most for survival, the red cell count. The oxidant–antioxidant imbalance, in other words, is not an epiphenomenon; it tracks with the disease’s most life-threatening consequence.

The clinical implications are potentially significant. If oxidative damage accelerates anaemia, then antioxidant therapy becomes a rational adjunct to antiprotozoal drugs such as atovaquone and azithromycin, which suppress but rarely eliminate B. gibsoni. Notably, the same research group has already reported a pilot study in which N-acetylcysteine, a glutathione precursor and well-known mucolytic drug, ameliorated oxidative stress and attenuated anaemia, the acute phase response, and hepatic injury in dogs with clinical B. gibsoni infection. The present study’s correlation data provide the pathophysiological rationale for that intervention, and they suggest that monitoring lipid peroxide and antioxidant indices could serve as a gauge of disease severity and treatment response. For a disease in which chronic carriers are the norm and complete parasitological cure is elusive, any strategy that protects the patient’s remaining red cells carries real value.

Beyond the therapy bench, the study carries a public health and diagnostic message for regions where dogs live alongside heavy tick pressure. The discordance between antibody detection, microscopy, and PCR means that a single negative test should never close the case, and the high prevalence of subclinical, PCR-positive infections in the cohort implies a large silent reservoir that perpetuates transmission. The ultrasound findings, particularly splenomegaly and high-gradient transudative ascites, offer clinicians bedside clues that babesiosis may be complicating patients thought to have primary hepatic or cardiac disease. As B. gibsoni continues its geographic spread, aided by dog movement, bite transmission, and expanding tick habitats, studies of this kind, grounded in real-world clinical populations and linking imaging, biochemistry, and redox biology, provide the comprehensive assessment framework that the field has needed to move from symptom management to mechanism-targeted care of one of the world’s most important canine parasitic diseases.

Subject of Research: Clinicopathological changes, abdominal ultrasound findings, and oxidative stress biomarkers in dogs naturally infected with Babesia gibsoni

Article Title: Comprehensive Assessment of Babesia gibsoni Infection in Dogs: Clinicopathological, Imaging, and Oxidative Stress Perspectives

Article References: Khan, N., Sandilya, A., Eregowda, C. G., Thakur, N., Jayappa, K., Sarma, K., Lalrinkima, H., Konwar, B., Debnath, G., Chanu, H. D., Das, C., Lalrinpuii, L. B., & Bayan, H. (2026). Comprehensive Assessment of Babesia gibsoni Infection in Dogs: Clinicopathological, Imaging, and Oxidative Stress Perspectives. Acta Parasitologica, 71(5), Article 236. https://doi.org/10.1007/s11686-026-01421-y

Image Credits: AI Generated

DOI: 10.1007/s11686-026-01421-y

Keywords: Babesia gibsoni, canine babesiosis, dogs, anaemia, oxidative stress, lipid peroxidation, glutathione, total antioxidant capacity, thrombocytopaenia, ultrasonography, PCR diagnosis, India

The problem the researchers set out to tackle is more insidious than either stress alone. Salinity does not simply dehydrate plants; it also changes soil chemistry in ways that make heavy metals more mobile and more available for uptake. Earlier work cited by the team, including studies on cadmium mobility in saline soils, has shown that sodium salts can displace metal ions from soil particles, releasing them into the soil solution where roots readily absorb them. In the experimental soil used in this study, which had an electrical conductivity of 9.06 decisiemens per meter, wheat plants accumulated substantially more sodium, copper, lead and cadmium than plants grown under normal conditions.

The consequences for the plants were severe. Across two growing seasons, salinity combined with heavy metal contamination raised leaf sodium concentrations by roughly 50 to 53 percent, while leaf contents of copper rose by about 24 percent, lead by 66 to 87 percent and cadmium by 36 to 41 percent. The contaminated plants also accumulated more nitrate and nitrite, compounds that are undesirable in grain destined for human consumption. The physiological toll was reflected in the harvest: straw yields fell by about 30 to 35 percent and grain yields by nearly 32 percent compared with unstressed controls.

At the biochemical level, the stressed plants were fighting a losing battle against reactive oxygen species. Salinity and heavy metals both trigger the overproduction of these destructive molecules, which damage membranes, proteins and DNA. The plants responded by ramping up their enzymatic antioxidant defenses—superoxide dismutase, catalase and guaiacol peroxidase—and by elevating their pools of glutathione, a tripeptide that sits at the heart of the cellular redox system. Yet protein content declined, and the levels of essential macronutrients such as nitrogen, phosphorus and calcium, along with micronutrients including iron, manganese and zinc, all dropped. The plants were essentially starving while simultaneously being poisoned.

The intervention tested by the team was elegantly simple. Seeds were primed in either water, a 3 percent moringa leaf extract, a 1 millimolar glutathione solution, or a combination, and the same solutions were then applied as foliar sprays as the plants developed. Moringa oleifera, often called the miracle tree, is rich in antioxidants, vitamins, minerals and growth-promoting substances, and its leaf extract has previously been shown to alleviate salt and cadmium stress in several crops. Glutathione, meanwhile, is the plant’s own master antioxidant, participating directly in the detoxification of reactive oxygen species and in the chelation and sequestration of heavy metals.

The results of the sequenced application were striking. Plants that received both moringa leaf extract and glutathione, as seed priming followed by foliar spray, showed increases in superoxide dismutase activity of roughly 45 to 49 percent and in guaiacol peroxidase activity of 51 to 56 percent compared with stressed, untreated plants. Total protein content climbed by about 32 to 33 percent, and glutathione levels themselves surged by 60 to 70 percent, suggesting that the treatment primed the plants’ internal antioxidant machinery rather than merely supplementing it from outside.

Just as importantly, the treatment restored nutritional balance. Leaf concentrations of nitrogen rose by 28 to 51 percent, phosphorus by nearly 48 to 50 percent, potassium by 20 to 26 percent and calcium by 33 to 53 percent. Micronutrients followed the same pattern: leaf iron increased by 33 to 51 percent, zinc by 48 to 54 percent and manganese by about 36 percent, with similarly large gains in the grain. Because iron, zinc and manganese deficiencies affect billions of people worldwide, the finding that this treatment can biofortify wheat grain while detoxifying it is among the most consequential aspects of the work.

At the same time, the toxic load in the plants fell sharply. Leaf cadmium declined by 47 to 50 percent and lead by 48 to 49 percent, while grain cadmium dropped by 29 to 30 percent, lead by 47 to 54 percent and copper by about 26 percent. Leaf sodium, the principal driver of salt toxicity, fell by 40 to 45 percent, and grain nitrate and nitrite contents decreased by 47 to 54 percent and 54 to 61 percent respectively. The combined effect was a substantial recovery in productivity, with treated plants producing markedly higher straw and grain yields than their untreated, stressed counterparts.

The mechanism, as the authors describe it, is a coordinated restoration of homeostasis. By boosting the antioxidant defense system, the treatment limits the oxidative damage that heavy metals and sodium inflict on cells. By improving nutrient uptake, it counteracts the competitive interference that sodium causes with potassium, calcium and other essential elements. And by reducing the accumulation of toxic ions, it frees the plant’s metabolic resources for growth and grain filling rather than repair. The sequenced approach—priming seeds to establish defenses early, then reinforcing them with foliar sprays during critical growth stages—appears to be key, consistent with the team’s earlier work showing that sequenced glutathione and biostimulant applications improve wheat’s adaptation to salinity.

For agriculture in arid and semi-arid regions, where saline and contaminated soils are spreading, the implications are considerable. Both moringa leaf extract and glutathione are inexpensive, environmentally benign and easy to apply, making the strategy accessible to smallholder farmers who cannot afford soil remediation or expensive genetic solutions. The study, funded by the Deanship of Scientific Research at King Abdulaziz University, demonstrates that crop protection on degraded land need not begin in the soil itself; it can begin in the seed and the leaf. If field-scale trials confirm these two-season results, a tree extract and a common cellular antioxidant could become standard tools for growing safer, more nutritious wheat on some of the world’s most compromised farmland.

Subject of Research: Alleviation of combined salinity and heavy metal stress in wheat using moringa leaf extract and glutathione

Article Title: Glutathione and moringa leaf extract improve wheat tolerance to heavy metal-contaminated saline soil by regulation of antioxidant defense system and nutrient balance

Article References: Alamri, A. M., Rehman, H. U., Khalid, F., Alharby, H. F., Majrashi, A., Abdulmajeed, A. M., & Rady, M. M. (2026). Glutathione and moringa leaf extract improve wheat tolerance to heavy metal-contaminated saline soil by regulation of antioxidant defense system and nutrient balance. Plant Cell Reports, 45(11), Article 329. https://doi.org/10.1007/s00299-026-04010-5

Image Credits: AI Generated

DOI: 10.1007/s00299-026-04010-5

Keywords: wheat, salinity stress, heavy metals, glutathione, moringa leaf extract, antioxidant defense, seed priming, foliar spray, nutrient balance, grain quality, cadmium, soil contamination