The redox-sensitive GSK3β is a key regulator of glomerular podocyte injury in type 2 diabetic kidney disease

Emerging evidence suggests that GSK3β, a redox-sensitive transducer downstream of insulin signaling, acts as a convergent point for myriad pathways implicated in kidney injury, repair, and regeneration. However, its role in diabetic kidney disease remains controversial. In cultured glomerular podocytes, exposure to a milieu of type 2 diabetes elicited prominent signs of podocyte injury and degeneration, marked by loss of homeostatic marker proteins like synaptopodin, actin cytoskeleton disruption, oxidative stress, apoptosis, and stress-induced premature senescence, as shown by increased staining for senescence-associated β-galactosidase activity, amplified formation of γH2AX foci, and elevated expression of mediators of senescence signaling, like p21 and p16INK4A. These degenerative changes coincided with GSK3β hyperactivity, as evidenced by GSK3β overexpression and reduced inhibitory phosphorylation of GSK3β, and were averted by tideglusib, a highly-selective small molecule inhibitor of GSK3β. In agreement, post-hoc analysis of a publicly-available glomerular transcriptomics dataset from patients with type 2 diabetic nephropathy revealed that the curated diabetic nephropathy-related gene set was enriched in high GSK3β expression group. Mechanistically, GSK3β-modulated nuclear factor Nrf2 signaling is involved in diabetic podocytopathy, because GSK3β knockdown reinforced Nrf2 antioxidant response and suppressed oxidative stress, resulting in an improvement in podocyte injury and senescence. Conversely, ectopic expression of the constitutively active mutant of GSK3β impaired Nrf2 antioxidant response and augmented oxidative stress, culminating in an exacerbated diabetic podocyte injury and senescence. Moreover, IRS-1 was found to be a cognate substrate of GSK3β for phosphorylation at IRS-1S332, which negatively regulates IRS-1 activity. GSK3β hyperactivity promoted IRS-1 phosphorylation, denoting a desensitized insulin signaling. Consistently, in vivo in db/db mice with diabetic nephropathy, GSK3β was hyperactive in glomerular podocytes, associated with IRS-1 hyperphosphorylation, impaired Nrf2 response and premature senescence. Our finding suggests that GSK3β is likely a novel therapeutic target for treating type 2 diabetic glomerular injury.

Gradual effects of gradient concentrations of perfluorooctane sulfonate on the antioxidant ability and gut microbiota of red claw crayfish (Cherax quadricarinatus)

Perfluorooctane sulfonate (PFOS) is a typical persistent organic pollutant that is characterized by environmental persistence, bioaccumulation, and toxicity. In this study, we investigated the gut microbial response of the red claw crayfish Cherax quadricarinatus after 28 days of exposure to 0 ng/L, 1 ng/L, 10 μg/L, or 10 mg/L of PFOS as a stressor. We measured oxidative stress-related enzyme activities and expression of molecules related to detoxification mechanisms to evaluate the toxic effects of PFOS. We found that PFOS disturbed microbial homeostasis in the gut of C. quadricarinatus, resulting in increased abundance of the pathogen Shewanella and decreased abundance of the beneficial bacterium Lactobacillus. The latter especially disturbed amino acid transport and carbohydrate transport. We also found that the activities of glutathione S-transferase and glutathione peroxidase were positively correlated with the expression levels of cytochrome P450 genes (GST1-1, GSTP, GSTK1, HPGDS, UGT5), which are products of PFOS-induced oxidative stress and play an antioxidant role in the body. The results of this study provided valuable ecotoxicological data to better understand the biological fate and effects of PFOS in C. quadricarinatus.

Transcriptomic profiles and diagnostic biomarkers in the Mediterranean seagrasses Posidonia oceanica and Cymodocea nodosa reveal mechanistic insights of adaptative strategies upon desalination brine stress

Seawater desalination by reverse osmosis is growing exponentially due to water scarcity. Byproducts of this process (e.g. brines), are generally discharged directly into the coastal ecosystem, causing detrimental effects, on benthic organisms. Understanding the cellular stress response of these organisms (biomarkers), could be crucial for establishing appropriate salinity thresholds for discharged brines. Early stress biomarkers can serve as valuable tools for monitoring the health status of brine-impacted organisms, enabling the prediction of long-term irreversible damage caused by the desalination industry. In this study, we conducted laboratory-controlled experiments to assess cellular and molecular biomarkers against brine exposure in two salinity-sensitive Mediterranean seagrasses: Posidonia oceanica and Cymodocea nodosa. Treatments involved exposure to 39, 41, and 43 psu, for 6 h and 7 days. Results indicated that photosynthetic performance remained unaffected across all treatments. However, under 43 psu, P. oceanica and C. nodosa exhibited lipid oxidative damage, which occurred earlier in P. oceanica. Additionally, P. oceanica displayed an antioxidant response at higher salinities by accumulating phenolic compounds within 6 h and ascorbate within 7 d; whereas for C. nodosa the predominant antioxidant mechanisms were phenolic compounds accumulation and total radical scavenging activity, which was evident after 7 d of brines exposure. Finally, transcriptomic analyses in P. oceanica exposed to 43 psu for 7 days revealed a poor up-regulation of genes associated with brassinosteroid response and abiotic stress response, while a high down-regulation of genes related to primary metabolism was detected. In C. nodosa, up-regulated genes were involved in DNA repair, cell cycle regulation, and reproduction, while down-regulated genes were mainly associated with photosynthesis and ribosome assembly. Overall, these findings suggest that 43 psu is a critical salinity-damage threshold for both seagrasses; and despite the moderate overexpression of several transcripts that could confer salt tolerance, genes involved in essential biological processes were severely downregulated.

The crosstalk between photoperiod and early mild stress on juvenile oscar (Astronotus ocellatus) after acute stress

Early mild stress (EMS) is like preparedness and might help fish deal with stress appropriately. This study investigated how EMS and photoperiod changes can impact growth, haematology, blood biochemistry, immunological response, antioxidant system, liver enzymes, and stress response of oscar (Astronotus ocellatus; 7.29 ± 0.96 g) before and after acute confinement stress (AC stress). Ten experimental treatments included five different photoperiods 8L16D (08:16 light to dark), 12L12D (12:12 light to dark), 16L8D (16:08 light to dark), 20L4D (20:04 light to dark), and 24L0D (24:00 light to dark), and these five photoperiod schedules were conducted in an EMS condition. After 9 weeks, no significant differences were found in growth parameters, survival rate, and body composition. At the end of the experiment and after AC stress, fish farmed in 24 light hours had the lowest haematocrit, white blood cells, total protein, blood performance, lysozyme, immunoglobulin M, complement C3, superoxide dismutase, and catalase. Fish that experienced EMS had significantly higher survival rates than those farmed in normal conditions (80.67% vs 61.33%). In conclusion, considering all measured parameters, 8-h light can be suggested as an optimum photoperiod for this fish species. Under 24L0D (no EMS) conditions, there were many negative effects apparent. In addition, a positive effect of EMS was evident in terms of survival after AC stress. AC stress decreased some health parameters under 24-h light treatment, while these results were not observed in EMS-exposed fish. Therefore, the EMS schedule can be a useful tool in preventing the negative effects of stress.

The combined effects of phenanthrene and micro-/nanoplastics mixtures on the cellular stress responses of the thick-shell mussel Mytilus coruscus

Pollution with complex mixtures of contaminants including micro- and nano-plastics (MNPs) and organic pollutants like polycyclic aromatic hydrocarbons (PAH) poses a major threat to coastal marine ecosystems. Toxic mechanisms of contaminant mixtures are not well understood in marine organisms. We studied the effects of single and combined exposures to polycyclic aromatic hydrocarbon phenanthrene (Phe) and MNPs mixture with sizes of 70 nm, 5 μm and 100 μm on the immune health and oxidative stress parameters in the thick-shell mussel Mytilus coruscus. Immune cells (hemocytes) were more sensitive to the pollutant-induced oxidative stress than the gills. In hemocytes of co-exposed mussels, elevated mortality, lower lysosomal content, high production of reactive oxygen species (ROS) and decrease mitochondrial were found. Disparate responses of antioxidant enzymes in the hemolymph (e.g. increased superoxide dismutase (SOD) activity without a corresponding increase in catalase (CAT) in Phe exposures and an increase in CAT without a change in SOD in MNPs exposures) suggests misbalance of the antioxidant defense in the pollutant-exposed mussels. Gill lacked pronounced oxidative stress response showing a decline in ROS and antioxidant levels. Tissue-specific single and combined effects of Phe and MNPs suggest variation in bioavailability and/or different sensitivity to these pollutants in the studied tissues. Notably, the combined effects of MNPs and Phe were additive or antagonistic, showing that MNPs do not enhance and occasionally mitigate the toxic effects of Phe on the hemocytes and the gills of the mussels. Overall, our study sheds light on the impact of long-term exposure to MNPs and Phe mixtures on mussels, showing high sensitivity of the immune system and modulation of the Phe toxicity by MNPs co-exposure. These findings that may have implications for understanding the impacts of combined PAH and MNPs pollution on the health of mussel populations from polluted coastal habitats.

Exposure to bisphenol A and fiber-type microplastics induce oxidative stress and cell damage in disk abalone Haliotis discus hannai: Bioaccumulation and toxicity

Along with environmental pollution caused by rapid economic development and industrialization, plastic waste is emerging as a global concern in relation to marine ecosystems and human health. Among the microplastics, fiber-type microfibers (MF) and bisphenol A (BPA), which are widely used as plasticizers, do not decompose well in the ocean, and tend to accumulate in organisms, generating an increased oxidative stress response. This study investigated the abalones' antioxidant and cell death responses following exposure to the environmental pollutants MF and BPA. Levels of malondialdehyde (MDA) and DNA damage increased over time, demonstrating the degree of lipid peroxidation and DNA damage in abalones exposed to individual and combined environmental conditions of MF and BPA. Compared to the single MF and BPA exposure groups, the combined exposure group showed a higher expression of antioxidant enzymes. A similar pattern was seen in the expression of the apoptosis enzyme caspase-3. Both MF and BPA caused oxidative stress and antioxidant enzymes were expressed to alleviate it, but it is believed that cell damage occurred because the stress level exceeded the allowed range.

Zika virus restriction of host antioxidant response is mediated by intracellular NS1 and reveals its ability to upregulate Bach1 expression

Zika virus (ZIKV), has gained global attention due to its association with severe disorders, including microcephaly and congenital Zika syndrome. We investigated the role of ZIKV nonstructural protein 1 (NS1) in altering the host's antioxidant response. Using a stable cell line expressing NS1, we found that NS1 significantly reduced the expression of antioxidant-related genes, including heme oxygenase 1 (HO-1), NAD(P)H quinone dehydrogenase 1 (NQO1), and sequestosome-1 (SQSTM1), which are regulated NRF2. Interestingly, this effect was attributed to increased expression of BACH1, a factor that competes with NRF2 for binding to certain antioxidant responsive elements (ARE). Thus, ZIKV NS1-mediated disruption of the antioxidant system is linked to BACH1 overexpression. These findings offer insights into ZIKV pathogenesis and suggest potential therapeutic strategies targeting the NRF2-BACH1 axis.

Regulation of Keap1-Nrf2 axis in temporal lobe epilepsy-hippocampal sclerosis patients may limit the seizure outcomes

BACKGROUND

Accumulation of reactive oxygen species (ROS) exacerbates neuronal loss during seizure-induced excitotoxicity. Keap1 (Kelch-like ECH-associated protein1)-nuclear factor erythroid 2-related factor 2 (Nrf2) axis is one of the known active antioxidant response mechanisms. Our study focused on finding the factors influencing Keap1-Nrf2 axis regulation in temporal lobe epilepsy (TLE) associated with hippocampal sclerosis (HS) patients.

METHODS

Based on post-surgical follow-up data, patient samples (n = 26) were categorized into class 1 (completely seizure-free) and class 2 (only focal-aware seizures/auras), as suggested by International League Against Epilepsy (ILAE). For molecular analyses, double immunofluorescence assay and Western blot analysis were employed.

RESULTS

A significant decrease in expression of Nrf2 (p < 0.005), HO-1; p < 0.02) and NADPH Quinone oxidoreductase1 (NQO1; p < 0.02) was observed in ILAE class 2. Keap1 (p < 0.02) and histone methyltransferases (HMTs) like SetD7 (SET7/9; SET domain-containing 7 histone lysine methyltransferase) (p < 0.009) and enhancer of zeste homolog 2 (EZH2; p < 0.02) and methylated histones viz., H3K4me1 (p < 0.001), H3K9me3 (p < 0.001), and H3K27me3 (p < 0.001) was upregulated in ILAE class 2. Nrf2-interacting proteins viz., p21 (p < 0.001) and heat shock protein 90 (HSP90; p < 0.03) increased in class 1 compared to class 2 patients.

CONCLUSION

Upregulation of HMTs and methylated histones can limit phase II antioxidant enzyme expression. Also, HSP90 and p21 that interfere with Keap1-Nrf2 interaction could contribute to a marginal increase in HO-1 and NQO1 expression despite histone methylation and Keap1. Based on our findings, we conclude that TLE-HS patients prone to seizure recurrence were found to have dysfunctional antioxidant response, in part, owing to Keap1-Nrf2 axis. The significance of Keap1-Nrf2 signaling mechanism in generation of phase II antioxidant response. Keap1-Nrf2 controls antioxidant response through regulation of phase II antioxidant enzymes like HO-1 (heme oxygenase-1), NQO1 (NADPH-Quinone Oxidoreductase1), and glutathione S-transferase (GST). Release of Nrf2 from negative regulation by Keap1 causes its translocation into nucleus, forming a complex with cAMP response-element binding protein (CBP) and small Maf proteins (sMaf). This complex subsequently binds antioxidant response element (ARE) and elicits and antioxidant response involving expression of phase II antioxidant enzymes. Reactive oxygen species (ROS) modify Cysteine 151 residue, p62 (sequsetosome-1), and interacts with Nrf2- binding site in Keap 1. p21 and HSP90 prevent Nrf2 interaction with Keap1. At transcriptional level, histone methyltransferases like EZH2 (enhancer of zeste homologue2), and SetD7 (SET7/9; SET domain-containing 7 histone lysine methyltransferase) and corresponding histone targets viz., H3K27me3, H3K9me3, and H3K4me1 influence Nrf2 and Keap1 expression respectively.

Performance evaluation, enzymatic activity change and metagenomic analysis of sequencing batch reactor under divalent zinc stress

Divalent zinc (Zn2+) are widely detected in domestic and industrial wastewater, and it is essential to evaluate the effect of Zn2+ on wastewater biological treatment process due to its bio-toxicity. In this study, the nitrogen removal rates and their corresponding enzymatic activities of sequencing batch reactor decreased with the increase of Zn2+ concentration. The Zn2+ accumulation in activated sludge caused significant antioxidant response, and the reactive oxygen species (ROS) production and antioxidant enzymatic activities were positively correlated with Zn2+ concentration. The presence of Zn2+ inhibited the metabolic pathways related to energy production and electron transport. The abundance decreases of nitrification and denitrification functional genes led to the deterioration of nitrogen removal performance under Zn2+ stress. The correlation analysis between functional gene modules and microbial genera revealed that Zoogloea had obvious Zn2+ resistance. This study can provide the insights into the influencing mechanism of Zn2+ on the biological nitrogen removal process.

Antifungal and elicitor activities of p-hydroxybenzoic acid for the control of aflatoxigenic Aspergillus flavus in kiwifruit

Aspergillus flavus not only reduces kiwifruit production but also synthesizes carcinogenic aflatoxins, resulting in a relevant threat to human health. p-Hydroxybenzoic acid (pHBA) is one of the most abundant phenolics in kiwifruit. In this study, pHBA was found to reduce A. flavus mycelial growth by blocking the fungal mitotic exit network (MEN) and cytokinesis and to inhibit the biosynthesis of aflatoxins B1 and B2. The application of pHBA promoted the accumulation of endogenous pHBA and induced oxidative stress in A. flavus-infected kiwifruit, resulting in an increase in H2O2 content and catalase (CAT) and superoxide dismutase (SOD) activities. Preventive and curative treatments with 5 mM pHBA reduced A. flavus advancement by 46.1% and 68.0%, respectively. Collectively, the antifungal and elicitor properties of pHBA were examined for the first time, revealing new insights into the role of pHBA in the defense response of kiwifruit against A. flavus infection.

USP13 deubiquitinates p62/SQSTM1 to induce autophagy and Nrf2 release for activating antioxidant response genes

SQSTM1/p62 (sequestosome 1) is a multifunctional protein that serves as a receptor for selective autophagy and scaffold. In selective autophagy, p62 functions as a bridge between polyubiquitinated proteins and autophagosomes. Further, p62 acts as a signaling hub for many cellular pathways including mTORC1, NF-κB, and Keap1-Nrf2. Post-translational modifications of p62, such as ubiquitination and phosphorylation, are known to determine its binding partners and regulate their intracellular functions. However, the mechanism of p62 deubiquitination remains unclear. In this study, we found that ubiquitin-specific protease 13 (USP13), a member of the USP family, directly binds p62 and removes ubiquitin at Lys7 (K7) of the PB1 domain. USP13-mediated p62 deubiquitination enhances p62 protein stability and facilitates p62 oligomerization, resulting in increased autophagy and degradation of Keap1, which is a negative regulator of the antioxidant response that promotes Nrf2 activation. Thus, USP13 can be considered a therapeutic target as a deubiquitination enzyme of p62 in autophagy-related diseases.

Sodium Butyrate Protects Against Intestinal Oxidative Damage and Neuroinflammation in the Prefrontal Cortex of Ulcerative Colitis Mice Model

Inflammatory bowel diseases (IBD) cause increased inflammatory signalling and oxidative damage. IBDs are correlated with an increased incidence of brain-related disorders suggesting that the gut-brain-axis exerts a pivotal role in IBD. Butyrate is one of the main microbial metabolites in the colon, and it can cross the blood-brain barrier, directly affecting the brain. We induced ulcerative colitis (UC) in mice utilizing dextran sodium sulfate (DSS) in the drinking water for 7 days. Animals were divided into four groups, receiving water or DSS and treated with saline or 0,066 g/kg of Sodium Butyrate for 7 days. We also used an integrative approach, combining bioinformatics functional network and experimental strategies to understand how butyrate may affect UC. Butyrate was able to attenuate colitis severity and intestinal inflammation. Butyrate protected the colon against oxidative damage in UC and protected the prefrontal cortex from neuroinflammation observed in DSS group. Immunocontent of tight junction proteins Claudin-5 and Occludin were reduced in colon of DSS group mice and butyrate was able to restore to control levels. Occludin and Claudin-5 decrease in DSS group indicate that an intestinal barrier disruption may lead to the increased influx of gut-derived molecules, causing neuroinflammation in the prefrontal cortex, observed by increased IBA-1 marker. The probable protection mechanism of butyrate treatment occurs through NRF2 through Nrf2 and HIF-1α activation and consequent activation of catalase and superoxide dismutase. Our data suggest that systemic inflammation associated with intestinal barrier disruption in UC leads to neuroinflammation in the prefrontal cortex, which was atenuated by butyrate.

The alleviation mechanisms of cadmium toxicity in Broussonetia papyrifera by arbuscular mycorrhizal symbiosis varied with different levels of cadmium stress

The alleviation of cadmium (Cd) toxicity in Broussonetia papyrifera by arbuscular mycorrhizal (AM) fungi are still not completely elucidated. This study investigated the effects of Rhizophagus irregularis on physiological and biochemical characteristics, and molecular regulation in B. papyrifera under different levels of Cd (0, 30, 90 and 270 mg kg-1 Cd) stress. Results showed that (1) AM symbiosis improved the growth and photosynthesis, enhanced ROS levels as stress signaling and maintained ROS balance under low and medium Cd stress. (2) AM symbiosis regulated AsA-GSH cycle to mitigate ROS overproduction under high Cd stress. (3) AM fungus can chelate more Cd under high Cd stress, increasing soil pH and GRSP content. (4) AM plants can fix or chelate more Cd by P in leaves and reserve more P in stems under high Cd stress. (5) AM symbioses increased root net Cd2+ influx and uptake under medium Cd stress but inhibited under high Cd stress, with upregulation of genes related heavy metals (HMs) transport under medium Cd stress and inhibited the transcription of genes related HMs transport under high Cd stress. Therefore, the alleviation mechanisms of Cd toxicity in B. papyrifera by R. irregularis symbiosis depends on the levels of Cd stress.

Oxidative status alteration during aerobic-dominant mixed and anaerobic-dominant mixed effort in judokas

This study aimed to depict the oxidative status variation in judokas during aerobic-dominant mixed effort (AeDME) and anaerobic-dominant mixed effort (AnDME). It is to be expected that the sporting commitment of Judo is a stimulus of oxidative stress leading to the recruitment of antioxidant responses. Blood samples were collected from 17 athletes at rest, immediately after a training session (AeDME) and after a 5-min bout (AnDME). AeDME and AnDME caused significant increases in malondialdehyde (MDA) (p < 0.01 and p < 0.001 respectively) and glutathione (GSH) (p = 0.018 and p < 0.001 respectively). Blood thiol concentrations decreased following AeDME and AnDME (p < 0.001) whilst catalase decreased significantly after AnDME (p = 0.026) only. Uric acid increased significantly after AnDME than after AeDME (p = 0.047) while, conversely, total bilirubin was higher after AnDME than after AeDME (p = 0.02). We may ultimately summarize that AeDME and AnDME caused oxidative stress, higher in AnDME, and some antioxidant response slightly higher in AnDME compared to AeDME. In sports, monitoring of oxidative stress status is recommended as part of the training regimen.

Ciprofloxacin enhances cadmium toxicity to earthworm Eisenia fetida by altering the gut microorganism composition

The concurrent existence of cadmium (Cd) and ciprofloxacin (CIP) in agricultural soils is very common, but presents a challenge to soil organisms. As more attention has been paid to the effect of toxic metals on the migration of antibiotic resistance genes, the critical role of the gut microbiota in CIP-modifying Cd toxicity in earthworms remains unclear. In this study, Eisenia fetida was exposed to Cd and CIP alone or in combination at environmentally relevant concentrations. Cd and CIP accumulation in earthworm increased as their respective spiked concentrations increased. In fact, Cd accumulation increased by 39.7% when 1 mg/kg CIP was added; however, the addition of Cd did not affect CIP uptake. Compared with exposure to Cd alone, a greater ingestion of Cd following combined exposure to Cd and 1 mg/kg CIP resulted in greater oxidative stress and energy metabolism disturbances in earthworms. The reactive oxygen species (ROS) contents and apoptosis rate of coelomocytes were more sensitive to Cd than these biochemical indicators. In fact, 1 mg/kg Cd induced the derivation of ROS. Similarly, the toxicity of Cd (5 mg/kg) to coelomocytes was promoted by CIP (1 mg/kg), ROS content in coelomocytes and the apoptosis rate increased by 29.2% and 113.1%, respectively, due to increased Cd accumulation. Further investigation of the gut microorganisms revealed that the decreased abundance of Streptomyces strains (known as Cd accumulation taxa) could be a critical factor for enhanced Cd accumulation and greater Cd toxicity to earthworms following exposure to both Cd and CIP; this was because this microorganism group was eliminated by the simultaneous ingestion of CIP. This study stressed the role of gut microorganisms in altering the toxicity of Cd and CIP combined contamination in soil organisms. More attention should be paid to the ecological risks of such combined contamination in soils.

In vitro immune and redox response induced by cationic cellulose-based nanomaterials

Cellulose nanocrystals (CNCs) display remarkable strength and physicochemical properties with significant potential applications. To better understand the potential adjuvanticity of a nanomaterial, it is important to investigate the extent of the immunological response, the mechanisms by which they elicit this response, and how this response is associated with their physicochemical characteristics. In this study, we investigated the potential mechanisms of immunomodulation and redox activity of two chemically related cationic CNC derivatives (CNC-METAC-1B and CNC-METAC-2B), using human peripheral blood mononuclear cells and mouse macrophage cells (J774A.1). Our data demonstrated that the biological effects caused by these nanomaterials occurred mainly with short term exposure. We observed opposite immunomodulatory activity between the tested nanomaterials. CNC-METAC-2B, induced IL-1β secretion at 2 h while CNC-METAC-1B decreased it at 24 h of treatment. In addition, both nanomaterials caused more noticeable increases in mitochondrial reactive oxygen species (ROS) at early time. The differences in apparent sizes of the two cationic nanomaterials could explain, at least in part, the discrepancies in biological effects, despite their closely related surface charges. This work provides initial insights about the complexity of the in vitro mechanism of action of these nanomaterials as well as foundation knowledge for the development of cationic CNCs as potential immunomodulators.

The effects of a polystyrene nanoplastic on the immune response and gut microbiota of Eriocheir sinensis and its post-recovery state

Although there is increasing concern about the toxicity of nanoplastics, the effects of nanoplastic exposure and subsequent recovery on immune responses, as well as antioxidant responses and gut microbiota, in crustaceans are rarely reported. In this study, the nonspecific immunity and antioxidant defense of Eriocheir sinensis were evaluated after acute exposure to various concentrations (0, 2.5, 5, 10 and 20 mg/L) of 75-nm polystyrene nanoplastics (PS-NPs) for 48 h, as well as after 7 days of recovery from the nanoplastic environment. The results showed that, after 48 h of exposure, nanoplastics were observed in the gills, hepatopancreas and gut. However, no nanoplastics were found in the gut after 7 days of recovery. Under nanoplastic-induced stress, Hc, Relish, proPO, and LITAF mRNA levels increased in the gills and hepatopancreas for 48 h. Expression of the myd88, Hc, Relish and proPO genes decreased in the gills during the 7-day recovery period. Exposure to nanoplastics for 48 h and recovery for 7 days significantly decreased the activities of lysozyme (LZM) alkaline phosphatase (AKP), total superoxide dismutase (SOD) and phenoloxidase (POD) and, glutathione peroxidase (GPX) in the hepatopancreas. Meanwhile, the relative abundance of pathogens exposed to 10 mg/L nanoplastics for 48 h increased at the species level, and these pathogens decreased significantly in the 7-day recovery period. These results suggested that exposure to nanoplastics for 48 h affected the activities of immune system enzymes and expression of immune-related genes in Eriocheir sinensis and altered the diversity and composition of their gut microbiota. E. sinensis could not recover from damage to the hepatopancreas within a 7-day recovery period. The results of this study provided insight into the effects of nanoplastics on crustaceans and it filled a gap in research on crustacean recovery after exposure to nanoplastics.

Embryonic development, hatchling performance and metabolic profile after egg exposure to environmentally relevant levels of chlorpyrifos in an aquatic turtle

The extensive use of organophosphorus insecticides poses a threat to the survival of non-target organisms. Ecotoxicological outcomes of embryonic exposure to insecticides are rarely evaluated in various oviparous species. In this study, soft-shelled turtle (Pelodiscus sinensis) eggs were incubated in moist substrate containing different levels (0, 2, 20 and 200 μg/kg) of chlorpyrifos to investigate its toxic effects on embryonic development and survival, and hatchling physiological performance. Chlorpyrifos exposure had no significant impacts on embryonic development rate and egg survival in P. sinensis. Similarly, embryonic chlorpyrifos exposure neither obviously affected the size and locomotor performance of hatchlings, nor changed the activities of superoxide dismutase and catalase, and content of malondialdehyde in their erythrocytes. Based on liquid chromatography-mass spectrometry analysis, minor metabolic perturbations related to amino acid, lipid and energy metabolism in hatchlings after embryonic chlorpyrifos exposure were revealed by hepatic metabolite profiling. Overall, our results suggested that embryonic exposure to environmentally relevant levels of chlorpyrifos had only a limited impact on physiological performances of hatchlings, although it would result in a potential risk of hepatotoxicity in P. sinensis.

Sub-chronic ammonia exposure induces hepatopancreatic damage, oxidative stress, and immune dysfunction in red swamp crayfish (Procambarus clarkii)

Ammonia, as one of the primary water pollutants in aquaculture, has been shown to induce a wide range of ecotoxicological effects on aquatic animals. In order to investigate the antioxidant and innate immune responses in crustaceans disrupted by ammonia, red swamp crayfish (Procambarus clarkii) were exposed to 0, 15, 30, and 50 mg/L total ammonia nitrogen for 30 d, the alterations of antioxidant responses as well as innate immunity were studied. The results showed that the severity of hepatopancreatic injury were aggravated by the increasing ammonia levels, which were mainly characterized by tubule lumen dilatation and vacuolization. The swollen mitochondria and disappeared mitochondria ridges suggested that oxidative stress induced by ammonia targets the mitochondria. Concurrently, enhanced MDA levels, and decreased GSH levels as well as the decreased transcription and activity of antioxidant enzymes, including SOD, CAT, and GPx were noticed, which suggested that high concentrations of ammonia exposure induce oxidative stress in P. clarkii. Furthermore, a significant decrease of the hemolymph ACP, AKP, and PO along with the significant downregulation of immune-related genes (ppo, hsp70, hsp90, alf1, ctl) jointly indicated that ammonia stress inhibited the innate immune function. Our findings demonstrated that sub-chronic ammonia stress induced hepatopancreatic injury and exert suppressive effects on the antioxidant capacity as well as innate immunity of P. clarkii. Our results provide a fundamental basis for the deleterious effects of ammonia stress on aquatic crustaceans.

Minor metabolomic disturbances induced by glyphosate-isopropylammonium exposure at environmentally relevant concentrations in an aquatic turtle, Pelodiscus sinensis

The ecotoxicological and environmental impacts of glyphosate-based herbicides have received considerable attention due to their extensive use globally. However, the potential for adverse effects in cultured non-fish vertebrate species are commonly ignored. In this study, effects on growth, indicators of functional performance, gut microbial diversity, liver antioxidant responses and metabolite profiles were evaluated in soft-shelled turtle hatchlings (Pelodiscus sinensis) exposed to different concentrations of glyphosate-isopropylammonium (0, 0.02, 0.2, 2 and 20 mg/L). No significant changes in growth or functional performance (food intake, swimming speed), gut microbiota, and liver antioxidant responses (SOD and CAT activities, MDA content) were observed in exposed turtles. However, hepatic metabolite profiles revealed distinct perturbations that primarily involved amino acid metabolism in turtles exposed to environmentally relevant concentrations. Overall, our results suggested that metabolite profiles may be more sensitive than phenotypic or general physiological endpoints and gut microbiota profiling, and indicate a potential mechanism of hepatotoxicity caused by glyphosate-isopropylammonium based on untargeted metabolomics analysis. Furthermore, the toxicity of glyphosate at environmentally relevant concentrations might be relatively minor in aquatic turtle species.

Behavioural response to toxic elements, detoxification and organ accumulation are time-of-day-dependent in zebrafish

Toxic elements, such as mercury (Hg) and arsenic (As), are major pollutants in aquatic environments, posing ecological threats to living organisms due to their toxicity and bioaccumulation. This paper investigated whether zebrafish response to Hg and As displayed day/night differences. Fish were exposed to either 35 μg/L of mercury chloride for 6 h or 65 mg/L of sodium arsenate for 4 h, at two different times of the day: mid-light (day; ML) and mid-darkness (night; MD). Fish were video-recorded to investigate their behavioural response and at the end of each trial, gills and liver samples were collected for gene expression measurement. Gills, liver and brain samples were also obtained to determine Hg and As concentration. A control group (non-exposed) was video-recorded and sampled too. The effect of Hg and As on zebrafish swimming activity and the expression of antioxidant and metallothionein genes was time-of-day-dependent, with a stronger response being observed during the day than at night. However, the neurobehavioural effect of Hg was more affected by the time of exposure than the effect of As. In addition, Hg concentration in the gills was significantly higher in zebrafish exposed at ML than at MD. Altogether, these findings suggest that zebrafish response to Hg and As is time-of-day-dependent and remark the importance of considering toxicity rhythms when using this fish species as a model in toxicological research.

DL-methionyl-DL-methionine as an efficient methionine source for promoting zootechnical performance and methionine-related pathways in the whiteleg shrimp (Penaeus vannamei)

Methionine (MET) supplementation is a current strategy to achieve shrimp requirement. Notwithstanding, the efficiency of the precisely formulated feeds can be diminished since shrimps are slow eaters and masticate feed externally that results in nutrient leaching. In this regard, a methionine dipeptide (DL-methionyl DL-methionine) benefits the feed industry by reducing MET water solubility while increasing its bioavailability. Therefore, the effects of feeding whiteleg shrimp (Penaeus vannamei) with increasing levels of methionine dipeptide were evaluated on zootechnical performance and methionine-, immune- and antioxidant-related pathways. A 74 d growth trial was conducted by feeding a control diet and four diets supplemented with AQUAVI^® Met-Met at 0·08, 0·12, 0·24 and 0·32% of DM. Diet digestibility, body amino acids (AA) composition and nitrogen metabolites, metabolic enzymes, oxidative status and gene expression were evaluated. It can be concluded that graded dietary increase of methionine dipeptide up to 0·24 % for 74 d translated in significant gains on the growth performance, feed efficiency, nutrient and nitrogen gain and shrimp survival. Moreover, it was showed that Met-Met dietary spare leads to an improvement of free-AA pool and nitrogen metabolites concentration and reduces the signs of oxidative stress. Finally, in a closer look to the MET-related pathways passive to be altered by Met-Met spare, a clear modulation of the described antioxidant and cell proliferation routes was detected.

Exogenous plant hormones alleviate As stress by regulating antioxidant defense system in Oryza sativa L

Plant hormones play essential roles in plant growth regulation and resistance to environmental pressure. A hydroponic experiment was conducted using Zhongjiazao 17 rice to explore the effects of exogenous plant hormones on antioxidant response and As accumulation in rice under As stress. Melatonin (MT), 2,4-epibrassinolide (EBL), and jasmonic acid (JA) reduced the As content in seedlings significantly by 13.4% (MT)-32.5% (EBL) under 5 µM As stress. Three hormones increased superoxide dismutase (SOD), peroxidase (POD), and catalase (CAT) activities, and glutathione (GSH) content significantly (2.2%-82.9%) in 5 µM As stress condition, whereas the levels of H₂O₂ and malondialdehyde (MDA) were reduced significantly (32.3%-78.1%). Plant hormone addition reduced the As content in seedlings significantly by 18.2% (JA)-33.3% (MT) under 25 µM As stress. SOD, POD, and CAT activities and GSH content in seedlings increased significantly (5.6-90.4%) with three hormones addition in 25 µM As stress, whereas the levels of H₂O₂, O₂˙¯, and MDA reduced significantly (20.9-73.0%). Staining with 2',7'-dichlorodihydrofluorescein diacetate and nitroblue tetrazolium showed that green fluorescence and blue spots decreased gradually in hormone-treated seedlings, further confirming that the exogenous addition of hormones weakened the oxidative stress of As to seedlings. Oxidative damage by As stress was reduced more by EBL than by the other hormones MT or JA. Totally, exogenous plant hormone can alleviate As stress in rice by activating enzyme activity of antioxidant defense system and scavenging reactive oxygen species, thus reducing oxidative damage and As accumulation in rice seedlings.

Redox Status in Retinitis Pigmentosa

Retinitis pigmentosa (RP) is the most common form of inherited retinal dystrophy characterized by the progressive loss of vision. It is a rare disease. Despite being a genetic disease, its progression is influenced by oxidative damage and chemokines and cytokines released by the activated immune cells (e.g., macrophages or microglia). The role of oxidative stress is very important in the retina. Rods are the main consumers of oxygen (O2), so they are constantly exposed to oxidative stress and lipid peroxidation. According to the oxidative hypothesis, after rod death in the early stages of the disease, O2 would accumulate in large quantities in the retina, producing hyperoxia and favoring the accumulation of reactive oxygen species and reactive nitrogen species that would cause oxidative damage to lipids, proteins, and DNA, exacerbating the process of retinal degeneration. Evidence shows alterations in the antioxidant-oxidant state in patients and in animal models of RP. In recent years, therapeutic approaches aimed at reducing oxidative stress have emerged as useful therapies to slow down the progression of RP. We focus this review on oxidative stress and its relationship with the progression of RP.

Detoxification effects of ascorbic acid on the oxidative stress, neurotoxicity, and metallothionein (MT) gene expression in juvenile rockfish, Sebastes schlegelii by the dietary chromium exposure

Juvenile rockfish Sebastes schlegelii (mean length 10.8 ± 1.4 cm, and mean weight 31.7 ± 3.6 g) were exposed for 4 weeks with the different levels of dietary chromium (Cr⁶⁺) at 0, 120 and 240 mg/L and ascorbic acids (AsA) at 100, 200 and 400 mg/L. Superoxide dismutase (SOD) activity, glutathione S-transferase (GST) activity, and glutathione (GSH) level of liver and gill were evaluated as antioxidant response indicators for the 4 weeks exposure. The SOD and GST activity of liver and gill were substantially increased by the high concentrations of dietary Cr exposure, whereas a significant decrease was observed in the GSH levels of liver and gill. Metallothionein (MT) gene in liver was significant stimulated in the response to the dietary Cr exposure. In neurotoxicity, AChE activity was considerably inhibited in brain and muscle tissues by dietary Cr exposure. The high levels of AsA supplementation were highly effective to attenuate the alterations in the antioxidant responses, MT gene expression, and AChE activity by the dietary Cr exposure.

Life after death? Exploring biochemical and molecular changes following organismal death in green turtles, Chelonia mydas (Linnaeus, 1758)

Green turtles, Chelonia mydas, have been included in biomonitoring efforts given its status as an endangered species. Many studies, however, rely on samples from stranded animals, raising the question of how death affects important biochemical and molecular biomarkers. The goal of this study was to investigate post mortem fluctuations in the antioxidant response and metabolism of carbohydrates in the liver of C. mydas. Liver samples were obtained from six green turtles which were submitted to rehabilitation and euthanized due to the impossibility of recovery. Samples were collected immediately after death (t = 0) and at various time intervals (1, 2, 3, 4, 5, 6, 12, 18 and 24 h post mortem), frozen in liquid nitrogen and stored at -80 °C. The activities of catalase (CAT), glutathione peroxidase (GPx), glutathione reductase (GR) and glucose-6-phosphate dehydrogenase (G6PDH) were analyzed, as were the levels of lipid peroxidation, glycogen concentration, RNA integrity (RNA IQ) and transcript levels of carbonic anhydrase and pyruvate carboxylase genes. Comparison between post mortem intervals showed a temporal stability for all the biomarkers evaluated, suggesting that changes in biochemical and molecular parameters following green turtle death are not immediate, and metabolism may remain somewhat unaltered up to 24 h after death. Such stability may be associated with the overall lower metabolism of turtles, especially under an oxygen deprivation scenario such as organismal death. Overall, this study supports the use of biomarkers in sea turtles sampled within a period of 24 h post mortem for biomonitoring purposes, though it is recommended that post mortem fluctuations of particular biomarkers be evaluated prior to their application, given that proteins may show varying degrees of susceptibility to proteolysis.

Activity of low-molecular weight components of Larix sibirica antioxidant system under exposure to technogenic pollution

Changes in the antioxidant protection system of Larix sibirica Ledeb at different pollution levels caused by emissions from a large aluminum smelter (BrAS) have been studied. We revealed that the content of peroxide (H₂O₂) in the needles is a reliable marker of oxidative stress in the trees under pollution. The crucial role of non-enzymatic components, in particular, proline, phenolic compounds, ascorbic acid, glutathione, in reducing the level of free radicals in the needles cells was found. Proline concentration in the needles significantly rises with the increase in pollution levels from low to high. Under critical level pollution, it decreases by 40% compared to the background. The total content of ascorbic acid (ASC) in the needles of polluted trees varies slightly; however, there are significant changes in its various forms. With an increase in pollution to a high level, the content of the reduced form of ASC in the needles increases by 1.5-2.9 times compared to the background content. At a critical level of pollution, the total level of ascorbic acid and its reduced form falls, the content of the oxidized form reaches minimum values. The total content of phenolic compounds in the needles increased by 50-55%, concentration of flavonoids by 1.5-1.8 times, catechins by 1.9-2.5 times, proanthocyanidins by 45% compared to the background level under low, moderate, high pollution, whereas under critical pollution their content decreased. The absolute concentration of the reduced form glutathione in the needles falls by 1.9-3.0 times, the oxidized form increases by 1.5-2.0 times compared to the background. The ratio of reduced glutathione to oxidized glutathione decreased, especially during critical pollution. The data obtained show significant activation of Siberian larch biochemical protection at low, moderate and high levels of pollution by the aluminum smelter emissions. At a critical levels of contamination, a significant depletion of the pool of low-molecular antioxidants was observed.

Enhancement of the immobilization on microalgae protective effects and carbamazepine removal by Chlorella vulgaris

Carbamazepine (CBZ) has drawn extensive attention due to their environmental threats. In this study, polyvinyl alcohol-sodium alginate polymers to immobilize Chlorella vulgaris (FACHB-8) were used to investigate whether immobilization can facilitate microalgae to alleviate the CBZ stress and enhance CBZ removal. The results showed that after immobilized treatment, the biomass of microalgae increased by approximately 20%, the maximum level of malondialdehyde content decreased from 28 to 13 μmol/g, and the photosynthetic capacity of F_V/F_M recovered to 90% of the control group. The CBZ removal rate increased from 67 to 84% by immobilization at a CBZ concentration of 80 mg·L^-1. The results indicated that immobilization technology can effectively protect microalgae from CBZ toxicity and improve the removal of CBZ, especially at high concentrations (> 50 mg/L). Biodegradation was the dominant pathway for microalgae to remove carbamazepine. This study added the understanding of the microalgae responses under immobilization and the interactions between immobilized microalgae and CBZ removal, thereby providing a novel insight into microalgae technology in high concentration wastewater treatments.

Nrf1 is an indispensable redox-determining factor for mitochondrial homeostasis by integrating multi-hierarchical regulatory networks

To defend against a vast variety of challenges in oxygenated environments, all life forms have evolutionally established a set of antioxidants, detoxification, and cytoprotective systems during natural selection and adaptive survival, to maintain cell redox homeostasis and organ integrity in the healthy development and growth. Such antioxidant defense systems are predominantly regulated by two key transcription factors Nrf1 and Nrf2, but the underlying mechanism(s) for their coordinated redox control remains elusive. Here, we found that loss of full-length Nrf1 led to a dramatic increase in reactive oxygen species (ROS) and oxidative damages in Nrf1α-∕- cells, and this increase was not eliminated by drastic elevation of Nrf2, even though the antioxidant systems were also substantially enhanced by hyperactive Nrf2. Further studies revealed that the increased ROS production in Nrf1α-∕- resulted from a striking impairment in the mitochondrial oxidative respiratory chain and its gene expression regulated by nuclear respiratory factors, called αPalNRF1 and GABPNRF2. In addition to the antioxidant capacity of cells, glycolysis was greatly augmented by aberrantly-elevated Nrf2, so to partially relieve the cellular energy demands, but aggravate its mitochondrial stress. The generation of ROS was also differentially regulated by Nrf1 and Nrf2 through miR-195 and/or mIR-497-mediated UCP2 pathway. Consequently, the epithelial-mesenchymal transformation (EMT) of Nrf1α-∕- cells was activated by putative ROS-stimulated signaling via MAPK, HIF1α, NF-ƙB, PI3K and AKT, all players involved in cancer development and progression. Taken together, it is inferable that Nrf1 acts as a potent integrator of redox regulation by multi-hierarchical networks.

Keap 1: The new Janus word on the block

Here we draw insights from the latest serendipitous findings made on the opposing roles of a proposed drug-target protein Keap1. We weigh up how natural reactive electrophiles and electrophilic small-molecule drugs in clinical use directly impinge on seemingly conflicting, yet both Keap1-electrophile-modification-dependent, cell-survival- vs. cell-death-promoting behaviors. In the process, we convey how understanding reactive chemical-signal regulation at the single-protein-specific level is an enabling necessity in deconstructing otherwise intricate reactive-small-molecule-responsive cellular pathways. We hope this opinion piece further spurs the broader interests of basic and pharmaceutical research communities toward better understanding of molecular mechanisms underpinning reactive small-molecule-regulated signaling subsystems.

The effect of a polystyrene nanoplastic on the intestinal microbes and oxidative stress defense of the freshwater crayfish, Procambarus clarkii

The widespread generation and accumulation of plastic waste has become a globally recognized problem. However, there are limited reports on the adverse effects of nanomaterials on freshwater crustaceans. This study tested the acute effects of different concentrations (0, 5, 10, and 20 mg/L) after 48 h exposure of 75 nm polystyrene nanoplastic on intestinal microbes, and oxidative stress parameters of freshwater crayfish, Procambarus clarkii. High-throughput sequencing analysis revealed the richness, diversity, and composition of intestinal microbiota in P. clarkii exposed to polystyrene nanoplastic. At the genus level, abundances of Lactobacillus, Faecalibaculum, Niveibacterium, and Candidatus Bacilloplasma were significantly different. The reduced abundance of Lactobacillus could affect the balance of intestinal microbes through quantitative disadvantage, which may lead to reduced immunity of P. clarkii. Streptococcus salivarius, Clostridium butyricum and Lachnospiraceae bacterium10-1 in intestinal tract reached maximum abundance at a polystyrene concentration of 20 mg/L. The increase in the number of some pathogenic bacteria may upset the balance of intestinal microorganisms through the number of dominance, and the decrease in the relative abundance of lactic acid bacteria. Probiotics, such as Lactobacillus salivarius, Lactobacillus murinus, Lactobacillus gasseri, Lactobacillus reuteri, Lactobacillus iners AB-1, and Lactobacillus crispatus in the intestinal tract reached the lowest value at a concentration of 10 mg/L. The reduced abundance of Lactobacillus can affect the balance of intestinal microbes through quantitative disadvantage, which may lead to reduced immunity in P. clarkii. At nanoplastic 10 mg/L, the relative abundance of intestinal pathogens increased, while the relative abundance of lactic acid bacteria and other probiotics decreased. With increases in nanoplastic concentrations, the values of glutathione (GSH), superoxide dismutase (SOD), acid phosphatase (ACP), lysozyme (LZM), alkaline phosphatase (AKP), peroxidase (POD), glutathione peroxidase (GPX), and protein carbonylation were significantly changed. Our data suggested that Lactobacillus may play an adjunctive role in the treatment of oxidative stress in P. clarkii exposed to 75 nm polystyrene. This study represents an important step towards a better understanding of the toxic effects of nanoplastics on aquatic crustaceans.

Cortisol modulates glucose metabolism and oxidative response after acute high temperature stress in Pacific oyster Crassostrea gigas

Cortisol is the main stress hormone that plays crucial roles in energy metabolism and immune response in vertebrates. In the present study, the homologues of 11β-hydroxysteroid dehydrogenase type 1 (designated Cg11β-HSD1) and 5α-reductase 1 (designated Cg5αR1), the key enzymes related to cortisol metabolism, were identified from Pacific oyster Crassostrea gigas. The Cg11β-HSD1 harbored a conserved SDR domain, and Cg5αR1 contained a Steroid_dh domain and three transmembrane domains. The mRNA transcripts of Cg11β-HSD1 and Cg5αR1 were constitutively expressed in all the examined tissues of oysters, with the highest expression level in haemocytes and labial palp, respectively. After acute high temperature stress (28 °C), the mRNA expression level of Cg11β-HSD1 in hepatopancreas significantly up-regulated at 6 h and 12 h, and that of Cg5αR1 significantly up-regulated at 6 h, compared with the Blank group (11 °C). The concentration of cortisol and glucose, as well as the activities of superoxide dismutase (SOD) and catalase (CAT) in hepatopancreas all significantly up-regulated after acute high temperature stress, while the glycogen concentration in adductor muscle decreased significantly at 6 h and 12 h. After the blockage of Cg11β-HSD1 with metyrapone, the cortisol concentration and the activities of SOD and CAT significantly decreased after acute high temperature stress, the glucose concentration in hepatopancreas significantly increased at 24 h, and the glycogen concentration in adductor muscle significantly increased at 6 h. These results collectively suggested that cortisol played a crucial role in regulating glucose metabolism and oxidative response in oysters upon acute high temperature stress.

Impacts of conventional and biodegradable microplastics on juvenile Lates calcarifer: Bioaccumulation, antioxidant response, microbiome, and proteome alteration

Discarded plastic bag is a main component of marine debris, posing potential threats to marine biota. This study was conducted to assess the potential effects of microplastics on juvenile Lates calcarifer. Fish were exposed via diet to two microplastic types from conventional polyethylene (PE) and biodegradable (Bio) plastic bags for 21 days. Antioxidative enzymes activity, intestinal microbiome and proteome were determined. PE and Bio microplastics were found to accumulate in gastrointestinal tracts, and no mortality was observed. Microplastics exposure did not induce significant antioxidant response except for the glutathione reductase (GR) modulation. Intestinal microbiome diversity decreased significantly in PE group based on Simpson index. Both types of microplastics induced proteome modulation by down-regulating proteins associated with immune homeostasis. Bio microplastics maintained higher intestinal microbial diversity and induced more proteins alteration than PE microplastics. This study provides toxicological insights into the impacts of conventional and biodegradable microplastics on juvenile L. calcarifer.

Fishing in troubled waters: Limited stress response to natural and synthetic microparticles in brown shrimp (Crangon crangon)

Marine invertebrates inhabiting estuaries and coastal areas are exposed to natural suspended particulate matter (SPM) like clay or diatom shells but also to anthropogenic particles like microplastics. SPM concentrations may reach 1 g per liter and more, comprising hundreds of millions of items in the size range of less than 100 μm. Suspension feeders and deposit feeders involuntarily ingest these particles along with their food. We investigated whether natural and anthropogenic microparticles at concentrations of 20 mg L^-1, which correspond to natural environmental SPM concentrations in coastal marine waters, are ingested by the brown shrimp Crangon crangon and whether these particles induce an oxidative stress response in digestive gland tissue. Shrimp were exposed to clay, silica, TiO₂, polyvinyl chloride (PVC), or polylactide microplastics (PLA) for 6, 12, 24, and 48 h, respectively. The activities of the anti-oxidative enzymes superoxide dismutase (SOD), glutathione peroxidase (GPx), and glutathione reductase (GR) were measured. All five particle types were ingested by the shrimp along with food. The presence of the particles in the shrimp stomach was verified by scanning electron microscopy. The activities of the anti-oxidative enzymes did not vary between animals exposed to different types of microparticles and control animals that did not receive particles. The temporal activity differed between the three enzymes. The lack of a specific biochemical response may reflect an adaptation of C. crangon to life in an environment where frequent ingestion of non-digestible microparticles is unavoidable and continuous maintenance of inducible biochemical defense would be energetically costly. Habitat characteristics as well as natural feeding habits may be important factors to consider in the interpretation of hazard and species-specific risk assessment.

Dietary nanoselenium supplementation for heat-stressed rainbow trout: effects on organizational structure, lipid changes, and biochemical parameters as well as heat-shock-protein- and selenoprotein-related gene expression

Nanoselenium (nano-Se) shows unique protective effects against environmental heat stress in rainbow trout as a selenium source additive and free radical scavenger. Accordingly, we investigated the effects of supplementation with different levels of nano-Se (0, 5, and 10 mg/kg) and before and after heat stress (24°C) for different treatment times on the dynamic changes of rainbow trout liver tissue structure, lipid changes, biochemical properties, and gene expression. The results showed that, under heat stress, the fish supplementation of 5 mg/kg nano-Se significantly increased liver glutathione peroxidase (GPx) activity and upregulated expression levels of HSP70b, HSP90a1, GPx1a, and Trx mRNAs, while liver alanine aminotransferase (ALT), aspartate aminotransferase (AST), superoxide dismutase (SOD), and malondialdehyde (MDA) levels as well as tissue structure damage and lipid accumulation were decreased. Combining the trends for the above indicators indicated that stress began to increase significantly at 8 h. It can be concluded that supplementation with 5 mg/kg nano-Se effectively alleviates stress damage in rainbow trout. Furthermore, stress at 24°C for 8 h can be thought of as a critical time point for the study of heat stress in rainbow trout, with significant changes in response but no serious damage. Thus, these results provide a reference for the addition of nano-Se to rainbow trout feed and provide theoretical and practical guidance for enhancing the resistance of rainbow trout to heat stress.

Comparative subcellular localization of NRF2 and KEAP1 during the hepatocellular carcinoma development in vivo

The activation of Nuclear Factor, Erythroid 2 Like 2 - Kelch Like ECH Associated Protein 1 (NRF2-KEAP1) signaling pathway plays a critical dual role by either protecting or promoting the carcinogenesis process. However, its activation or nuclear translocation during hepatocellular carcinoma (HCC) progression has not been addressed yet. This study characterizes the subcellular localization of both NRF2 and KEAP1 during diethylnitrosamine-induced hepatocarcinogenesis in the rat. NRF2-KEAP1 pathway was continuously activated along with the increased expression of its target genes, namely Nqo1, Hmox1, Gclc, and Ptgr1. Similarly, the nuclear translocation of NRF2, MAF, and KEAP1 increased in HCC cells from weeks 12 to 22 during HCC progression. Likewise, colocalization of NRF2 with KEAP1 was higher in the cell nuclei of HCC neoplastic nodules than in surrounding cells. Moreover, immunofluorescence analyses revealed that the interaction of KEAP1 with filamentous Actin was disrupted in HCC cells. This disruption may be contributing to the release and nuclear translocation of NRF2 since the cortical actin cytoskeleton serves as anchoring of KEAP1. In conclusion, this evidence indicates that NRF2 is progressively activated and promotes the progression of experimental HCC.

UBIAD1 and CoQ10 protect melanoma cells from lipid peroxidation-mediated cell death

Cutaneous melanoma is the deadliest type of skin cancer, although it accounts for a minority of all skin cancers. Oxidative stress is involved in all stages of melanomagenesis and cutaneous melanoma can sustain a much higher load of Reactive Oxygen Species (ROS) than normal tissues. Melanoma cells exploit specific antioxidant machinery to support redox homeostasis. The enzyme UBIA prenyltransferase domain-containing protein 1 (UBIAD1) is responsible for the biosynthesis of non-mitochondrial CoQ10 and plays an important role as antioxidant enzyme. Whether UBIAD1 is involved in melanoma progression has not been addressed, yet. Here, we provide evidence that UBIAD1 expression is associated with poor overall survival (OS) in human melanoma patients. Furthermore, UBIAD1 and CoQ10 levels are upregulated in melanoma cells with respect to melanocytes. We show that UBIAD1 and plasma membrane CoQ10 sustain melanoma cell survival and proliferation by preventing lipid peroxidation and cell death. Additionally, we show that the NAD(P)H Quinone Dehydrogenase 1 (NQO1), responsible for the 2-electron reduction of CoQ10 on plasma membranes, acts downstream of UBIAD1 to support melanoma survival. By showing that the CoQ10-producing enzyme UBIAD1 counteracts oxidative stress and lipid peroxidation events in cutaneous melanoma, this work may open to new therapeutic investigations based on UBIAD1/CoQ10 loss to cure melanoma.

Antioxidant Activity and Carotenoid Content Responses of Three Haematococcus sp. (Chlorophyta) Strains Exposed to Multiple Stressors

There has been increasing demands worldwide for bioactive compounds of natural origins, especially for the nutraceutical and food-supplement sectors. In this context, microalgae are viewed as sustainable sources of molecules with an array of health benefits. For instance, astaxanthin is a xanthophyll pigment with powerful antioxidant capacity produced by microalgae such as the chlorophyte Haematococcus sp., which is regarded as the most suitable organism for the mass production of this pigment. In this study, three Haematococcus sp. strains were cultivated using a batch mode under favourable conditions to promote vegetative growth. Their environment was altered in a second phase using a higher and constant illumination regime combined with either exposure to blue LED light, an osmotic shock (with NaCl addition) or supplementation with a phytohormone (gibberellic acid, GA3), a plant extract (ginger), an herbicide (molinate) or an oxidant reagent (hydrogen peroxide). The effects of these stressors were evaluated in terms of antioxidant response and astaxanthin and β-carotene accumulation. Overall, strain CCAP 34/7 returned the highest Trolox Equivalent Antioxidant Capacity (TEAC) response (14.1-49.1 µmoL Trolox eq. g^- 1 of DW), while the highest antioxidant response with the Folin-Ciocalteu (FC) was obtained for strain RPFW01 (62.5-155 µmoL Trolox eq. g^- 1 of DW). The highest β-β-carotene content was found in strain LAFW15 when supplemented with the ginger extract (4.8 mg. g^- 1). Strain RPFW01 exposed to blue light returned the highest astaxanthin yield (2.8 mg. g^- 1), 5-fold that of strain CCAP 34/7 on average. This study documents the importance of screening several strains when prospecting for species with potential to produce high-value metabolites. It highlights that strain-specific responses can ensue from exposure of cells to a variety of stressors, which is important for the adequate tailoring of a biorefinery pipeline.

Polystyrene nanoplastics affect seed germination, cell biology and physiology of rice seedlings in-short term treatments: Evidence of their internalization and translocation

Agroecosystems represent more and more a huge long-term sink for plastic compounds which inevitably undergo fragmentation, generating micro- and nano-plastics, with potential adverse effects on soil chemistry and living organisms. The present work was focused on the short-term effects of two different concentrations of polystyrene nanoplastics (PSNPs) (0.1 or 1 g L^-1 suspensions) on rice seedlings starting from seed germination, hypothesizing that possible acute effects on seedlings could depend on oxidative damage trigged by PSNPs internalization. As shown by TEM analysis, PSNPs were absorbed by roots and translocated to the shoots, affected root cell ultrastructure, the germination process, seedling growth and root mitotic activity, inducing cytogenetic aberration. Treatments were not correlated with increase in oxidative stress markers, but rather with a different pattern of their localization both in roots and in shoots, impairing H₂O₂ homeostasis and membrane damage, despite the adequate antioxidant response recorded. The harmful effects of PSNPs on cell biology and physiology of rice seedlings could be caused not only by a direct action by the PSNPs but also by changes in the production/diffusion of ROS at the tissue/cellular level.

Effects of Supplementary Selenium and Vitamin E on the Growth Performance, Antioxidant Enzyme Activity, and Gene Expression of Sea Cucumber Apostichopus japonicus

A 60-day feeding experiment was conducted to evaluate the effects of single selenomethionine (Se) and its mixture with vitamin E (VE) on the growth, antioxidant enzyme activities, and gene expression of juvenile sea cucumber Apostichopus japonicus. The design of the experiment contained two factors and 5 × 2 levels by means of adding various levels of Se and VE in the feed, i.e., combination of 0, 0.3, 0.6, 0.9, or 1.2 mg Se kg^-1 and 0 or 200 mg VE kg^-1. The results revealed that the specific growth rate and weight gain rate were the highest in the group with 0.3 mg Se kg^-1 and 200 mg VE kg^-1, followed by the group with 0.6 mg Se kg^-1 without VE. Se significantly improved the activities of amylase and protease with VE also imposed positive effect on the amylase activity. Glutathione peroxidase (GPX) activity was highest in the group with 1.2 mg Se kg^-1 and lowest with the basal diet. The activity of catalase (CAT) was increased while glutathione reductase (GR) activity was decreased in response to the addition of Se. No significant interactive effects of Se and VE on the enzyme activities were found except superoxide dismutase (SOD) activity. While relative expressions of GPX, CAT, and SOD genes were significantly responsive to the addition of dietary Se, VE significantly promoted the gene expression of SOD. The results suggested that Se and VE might have beneficial effects on the growth and antioxidant responses of A. japonicus.

Empowering antimicrobial photodynamic therapy of Staphylococcus aureus infections with potassium iodide

Infections caused by the Gram-positive bacterium Staphylococcus aureus, especially methicillin-resistant S. aureus (MRSA), impose a great burden on global healthcare systems. Thus, there is an urgent need for alternative approaches to fight staphylococcal infections, such as targeted antimicrobial photodynamic therapy (aPDT). We recently reported that targeted aPDT with the S. aureus-specific immunoconjugate 1D9-700DX can be effectively applied to eradicate MRSA. Nonetheless, the efficacy of aPDT in the human body may be diminished by powerful antioxidant activities. In particular, we observed that the efficacy of aPDT with 1D9-700DX towards MRSA was reduced in human plasma. Here we show that this antagonistic effect can be attributed to human serum albumin, which represents the largest pool of free thiols in plasma for trapping reactive oxygen species. Importantly, we also show that our targeted aPDT approach with 1D9-700DX can be empowered by the non-toxic inorganic salt potassium iodide (KI), which reacts with the singlet oxygen produced upon aPDT, resulting in the formation of free iodine. The targeted iodine formation allows full eradication of MRSA (more than 6-log reduction) without negatively affecting other non-targeted bacterial species or human cells. Altogether, we show that the addition of KI allows a drastic reduction of both the amount of the immunoconjugate 1D9-700DX and the irradiation time needed for effective elimination of MRSA by aPDT in the presence of human serum albumin.

Phenotypic and transcriptomic changes in the corneal epithelium following exposure to cigarette smoke

Cigarette smoke extract (CSE), a complex mixture of compounds, contributes to a range of eye diseases; however, the underlying pathophysiological responses to tobacco smoke remain ambiguous. The purpose of the present study was to evaluate the cigarette smoke-induced phenotypic and transcriptomic changes in the corneal epithelium with a view to elucidating the likely underlying mechanism. Accordingly, for the first time, we characterized the genome-wide effects of CSE on the corneal epithelium. The ocular surface of the mice in the experimental groups was exposed to CSE for 1 h per day for a period of one week, while mice in the control group were exposed to preservative-free artificial tears. Corneal fluorescein staining, in vivo confocal microscopy and scanning electron microscopy were performed to examine the corneal ultrastructure. Transcriptome sequencing and bioinformatics analysis were performed followed by RT-qPCR to validate gene expression changes. The results indicate that CSE exposure disrupted the structural integrity of the superficial epithelium, decreased the density of microvilli, and compromised the corneal epithelial barrier intactness. RNA-seq revealed 667 differentially expressed genes, and functional analysis highlighted the enhancement of several biological processes such as antioxidant activity and the response to oxidative stress. Moreover, the Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway enrichment analysis showed that glutathione metabolism and drug metabolism cytochrome P450 were the most relevant pathways contributing to the effects of CSE on the corneal epithelium. Protein-protein interaction (PPI) network analysis illustrated that GCLC, NQO1, and HMOX1 were the most relevant nodes. In conclusion, the present study indicates that CSE exposure induces changes in the phenotype and genotype of the corneal epithelium. The antioxidant response element is essential for counteracting the effects of cigarette smoke on this tissue layer. These results shed novel insights into how cigarette smoke damages this ocular surface.

Gonadal antioxidant responses to seawater acidification and hypoxia in the marine mussel Mytilus coruscus

This study investigated the combined effects of seawater acidification and hypoxia on the antioxidant response in gonads of the thick shell mussel Mytilus coruscus. Mussels were collected along the Shengsi Island, East China Sea, where oxygen and pH fluctuations frequently occur in summer. Mussels were exposed to three pH (8.1, 7.7, and 7.3) and two dissolved oxygen (DO) levels (6 and 2 mg L^-1) for 21 days followed by a 10-day recovery period (pH 8.1 and DO 6 mg L^-1). Gonad surface area (GSA) and activity of superoxide dismutase (SOD), catalase (CAT), glutathione peroxidase (GPX), glutathione (GSH), glutathione S-transferase (GST), and malondialdehyde (MDA) in gonad were measured at days 21 and 31. Complex and enzyme-specific responses were observed after the 21-day exposure period. Overall, PCA analysis revealed a stronger effect of pH than DO. Integrated biomarker response (IBR) analysis demonstrated that low pH and DO decreased mussel's antioxidant system and increased oxidative damage with potential consequences for gonad development. Mussels exposed to low pH and DO were only partly able to recover a normal enzymatic activity after 10-day recovery period. This suggests that mussels exposed to short-term pH and DO fluctuations event in the field may suffer lasting negative impacts.

Effect of silicon on the young maize plants exposed to nickel stress

Nickel (Ni) is involved in several physiological processes in plants but its excess in environment has many phytotoxic effects. Silicon (Si), an element required for optimal plant performance, has been shown to have beneficial effects for plants coping with various types of stresses. Here we studied the alleviative potential of Si (2.5 mM) added to hydroponically grown maize (Zea mays L.) plants under Ni (100 μM) stress. Ni decreased most of the growth parameters, total chlorophyll (Chl) and leaf relative water content (RWC), and catalase (CAT; EC 1.11.1.6) activity, while leaf water loss (LWL), contents of proline (Pro), hydrogen peroxide (H₂O₂) and ascorbate (AsA), membrane lipid peroxidation and activities of peroxidase (POX; EC 1.11.1.7) and superoxide dismutase (SOD; EC 1.15.1.1) were increased. Supplementation of Si to Ni-treated plants enhanced the leaf area, Chl content, RWC, CAT and POX (only in younger leaf) activities and decreased LWL, the contents of Pro (in younger leaf), H₂O₂ (roots) and AsA, lipid peroxidation and POX and SOD activities. We may conclude that Si mitigated the Ni-induced stress in maize by amelioration of the leaf water deficient status (Pro, RWC, LWL), enhancing membrane stability (MDA) and influencing enzymatic (SOD, POX, CAT) and non-enzymatic (Pro, AsA) defence systems. The increased Chl content and leaf area improve overall plant performance.

Induction of monoamine oxidase A-mediated oxidative stress and impairment of NRF2-antioxidant defence response by polyphenol-rich fraction of Bergenia ligulata sensitizes prostate cancer cells in vitro and in vivo

Prostate cancer (PCa) is a major cause of mortality and morbidity in men. Available therapies yield limited outcome. We explored anti-PCa activity in a polyphenol-rich fraction of Bergenia ligulata (PFBL), a plant used in Indian traditional and folk medicine for its anti-inflammatory and antineoplastic properties. PFBL constituted of about fifteen different compounds as per LCMS analysis induced apoptotic death in both androgen-dependent LNCaP and androgen-refractory PC3 and DU145 cells with little effect on NKE and WI38 cells. Further investigation revealed that PFBL mediates its function through upregulating ROS production by enhanced catalytic activity of Monoamine oxidase A (MAO-A). Notably, the differential inactivation of NRF2-antioxidant response pathway by PFBL resulted in death in PC3 versus NKE cells involving GSK-3β activity facilitated by AKT inhibition. PFBL efficiently reduced the PC3-tumor xenograft in NOD-SCID mice alone and in synergy with Paclitaxel. Tumor tissues in PFBL-treated mice showed upregulation of similar mechanism of cell death as observed in isolated PC3 cells i.e., elevation of MAO-A catalytic activity, ROS production accompanied by activation of β-TrCP-GSK-3β axis of NRF2 degradation. Blood counts, liver, and splenocyte sensitivity analyses justified the PFBL safety in the healthy mice. To our knowledge this is the first report of an activity that crippled NRF2 activation both in vitro and in vivo in response to MAO-A activation. Results of this study suggest the development of a novel treatment protocol utilizing PFBL to improve therapeutic outcome for patients with aggressive PCa which claims hundreds of thousands of lives each year.

Environmentally relevant concentrations of oxytetracycline and copper increased liver lipid deposition through inducing oxidative stress and mitochondria dysfunction in grass carp Ctenopharyngodon idella

Oxytetracycline (OTC) and Cu are prevalent in aquatic ecosystems and their pollution are issues of serious concern. The present working hypothesis is that the toxicity of Cu and OTC mixture on physiological activity of fish was different from single OTC and Cu alone. The present study indicated that, compared to single OTC or Cu alone, Cu+OTC mixture reduced growth performance and feed utilization of grass carp, escalated the contents of Cu, OTC and TG, increased lipogenesis, induced oxidative stress, damaged the mitochondrial structure and functions and inhibited the lipolysis in the liver tissues and hepatocytes of grass carp. Cu+OTC co-treatment significantly increased the mRNA abundances and protein expression of Nrf2. Moreover, we found that Cu+OTC mixture-induced oxidative stress promoted Nrf2 recruitment to the SREBP-1 promoter and increased SREBP-1-mediated lipogenesis; Nrf2 sited at the crossroads of oxidative stress and lipid metabolism, and mediated the regulation of oxidative stress and lipid metabolism. Our findings clearly indicated that OTC and Cu mixture differed in environmental risks from single antibiotic or metal element itself, and thus posed different toxicological responses to aquatic animals. Moreover, our findings suggested that Nrf2 functioned as an important antioxidant regulator linking oxidative stress to lipogenic metabolism, and thus elucidated a novel regulatory mechanism for lipid metabolism.

Photobiomodulation enhances facial nerve regeneration via activation of PI3K/Akt signaling pathway-mediated antioxidant response

Facial nerve dysfunction is a common clinical condition that leads to disfigurement and emotional distress in the affected individuals. This study aimed to evaluate whether photobiomodulation can enhance regeneration of crushed facial nerves and attempt to investigate the possible underlying mechanism of neuroprotective function and therapeutic target. Various parameters of photobiomodulation were assigned to the facial nerves and Schwann cells (SCs) separately during crushed injury in rats. Axonal regeneration, functional outcomes, and SC apoptosis, proliferation, and underlying mechanisms of action were evaluated by morphological, histopathological, and functional assessments, flow cytometry, western blotting, real-time PCR, and IncuCyte. The results showed that photobiomodulation improved axonal regeneration and functional recovery, and also promoted proliferation, and inhibited apoptosis of SCs, both of these were considered as the most effective parameters in 250mW group. In addition, the neuroprotective effects of photobiomodulation (500mW) were likely associated with oxidative stress-induced SC apoptosis via activation of the PI3K/Akt signaling pathway. Our results revealed that photobiomodulation significantly promoted axonal regeneration, functional recovery, and regeneration of the facial nucleus, and its mechanism was related to the up-regulation of the PI3K/Akt signaling pathway. These findings provide clear experimental evidence of photobiomodulation as an alternative therapeutic strategy for peripheral nerve damage.

Alpha-lipoic acid attenuates silica-induced pulmonary fibrosis by improving mitochondrial function via AMPK/PGC1α pathway activation in C57BL/6J mice

Silicosis is characterized by pulmonary interstitial fibrosis that arises as a result of chronic exposure to silica. The few available treatments only delay its progression. As α-lipoic acid (ALA) has been shown to have various beneficial effects, including mitoprotective, antioxidant, and anti-inflammatory effects, we hypothesized that it may exhibit therapeutic effects in pulmonary fibrosis. Therefore, in the present study, we used a murine model of silicosis to investigate whether supplementation with exogenous ALA could attenuate silica-induced pulmonary fibrosis by improving mitochondrial function. ALA was administered to the model mice via continuous intragastric administration for 28 days, and then the antioxidant and mitoprotective effects of ALA were evaluated. The results showed that ALA decreased the production of reactive oxygen species, protected mitochondria from silica-induced dysfunction, and inhibited extracellular matrix deposition. ALA also decreased hyperglycemia and hyperlipidemia. Activation of the mitochondrial AMPK/PGC1α pathway might be responsible for these ALA-mediated anti-fibrotic effects. Exogenous ALA blocked oxidative stress by activating NRF2. Taken together, these findings demonstrate that exogenous ALA effectively prevents the progression of silicosis in a murine model, likely by stimulating mitochondrial biogenesis and endogenous antioxidant responses. Therefore, ALA can potentially delay the progression of silica-induced pulmonary fibrosis.

Dietary cocoa ameliorates non-alcoholic fatty liver disease and increases markers of antioxidant response and mitochondrial biogenesis in high fat-fed mice

Cocoa powder, derived Theobroma cacao, is a popular food ingredient that is commonly consumed in chocolate. Epidemiological and human intervention studies have reported that chocolate consumption is associated with reduced risk of cardiometabolic diseases. Laboratory studies have reported the dietary supplementation with cocoa or cocoa polyphenols can improve obesity and obesity-related comorbidities in preclinical models. Non-alcoholic fatty liver disease (NAFLD), one such comorbidity, is a risk factor for cirrhosis and hepatocellular carcinoma. Limited studies have examined the effect of cocoa/chocolate on NAFLD and underlying hepatoprotective mechanisms. Here, we examined the hepatoprotective effects of dietary supplementation with 80 mg/g cocoa powder for 10 wks in high fat (HF)-fed obese male C57BL/6J mice. We found that cocoa-supplemented mice had lower rate of body weight gain (22%), hepatic triacylglycerols (28%), lipid peroxides (57%), and mitochondrial DNA damage (75%) than HF-fed controls. These changes were associated with higher hepatic superoxide dismutase and glutathione peroxidase enzyme activity and increased expression of markers of hepatic mitochondrial biogenesis. We also found that the hepatic protein expression of sirtuin 3 (SIRT3), and mRNA expression of peroxisome proliferator activated receptor g coactivator (PGC) 1a, nuclear respiratory factor 1, and forkhead box O3 were higher in cocoa-treated mice compared to HF-fed controls. These factors play a role in coordinating mitochondrial biogenesis and expression of mitochondrial antioxidant response factors. Our results indicate that cocoa supplementation can mitigate the severity of NAFLD in obese mice and that these effects are related to SIRT3/PGC1a-mediated increases in antioxidant response and mitochondrial biogenesis.

The Effect of Lactococcus lactis subsp. lactis PTCC 1403 on the Growth Performance, Digestive Enzymes Activity, Antioxidative Status, Immune Response, and Disease Resistance of Rainbow Trout (Oncorhynchus mykiss)

The effect of Lactococcus lactis subsp. lactis strain PTCC 1403 as a potential probiotic was investigated on the growth, hematobiochemical, immune responses, and resistance to Yersinia ruckeri infection in rainbow trout. A total of 240 fish were distributed into 12 fiberglass tanks representing four groups (× 3 replicates). Each tank was stocked with 20 fish (average initial weight: 11.81 ± 0.32 g) and fed L. lactis subsp. lactis PTCC 1403 at 0 (control, T0), 1 × 10⁹ (T1), 2 × 10⁹ (T2), and 3 × 10⁹ (T3) CFU/g feed for 8 weeks. The results showed enhanced protein efficiency ratio and reduced feed conversion ratio in the fish-fed T2 diet. Further, fish-fed T2 and T3 diets showed a significantly higher survival rate than the control (p < 0.05). Trypsin, lipase, and protease activities were increased in fish-fed L. lactis subsp. lactis PTCC 1403 compared to the control (p < 0.05). Fish fed with a T2 diet showed significantly (p < 0.05) lower glucose content than other groups. The blood lysozyme activity and IgM showed significantly (p < 0.05) higher values in fish-fed T2 and T3 diets than in other groups. The antioxidative responses were increased in fish-fed T2 and T3 diets (p < 0.05). After 7 days post-Y. ruckeri challenge, the cumulative mortality rate showed the lowest value in fish fed with T1 and T2 diets, while the highest value was recorded in the control group. In conclusion, the results revealed beneficial effects of L. lactis subsp. lactis PTCC 1403 on the feed efficiency, immune response, and resistance to Y. ruckeri infection in rainbow trout.