Accumulation Of Reactive Oxygen Species Research Articles

Protein P5 of pear chlorotic leaf spot-associated virus is a pathogenic factor that suppresses RNA silencing and enhances virus movement.

Pear chlorotic leaf spot-associated virus (PCLSaV) is a newly described emaravirus that infects pear trees. The virus genome consists of at least five single-stranded, negative-sense RNAs. The P5 encoded by RNA5 is unique to PCLSaV. In this study, the RNA silencing suppression (RSS) activity of P5 and its subcellular localization were determined in Nicotiana benthamiana plants by Agrobacterium tumefaciens-mediated expression assays and green fluorescent protein RNA silencing induction. Protein P5 partially suppressed local RNA silencing, strongly suppressed systemic RNA silencing and triggered reactive oxygen species accumulation. The P5 self-interacted and showed subcellular locations in plasmodesmata, endoplasmic reticulum and nucleus. Furthermore, P5 rescued the cell-to-cell movement of a movement defective mutant PVXΔP25 of potato virus X (PVX) and enhanced the pathogenicity of PVX. The N-terminal 1-89 amino acids of the P5 were responsible for the self-interaction ability and RSS activity, for which the signal peptide at positions 1-19 was indispensable. This study demonstrated the function of an emaravirus protein as a pathogenic factor suppressing plant RNA silencing to enhance virus infection and as an enhancer of virus movement.

Reactive Oxygen Species in Cystic Kidney Disease.

Polycystic kidney disease (PKD) is a rare but significant renal condition with major implications for global acute and chronic patient care. Oxidative stress and reactive oxygen species (ROS) can significantly alter its pathophysiology, clinical outcomes, and treatment, contributing to negative outcomes, including hypertension, chronic kidney disease, and kidney failure. Inflammation from ROS and existing cysts propagate the generation and accumulation of ROS, exacerbating kidney injury, pro-fibrotic signaling cascades, and interstitial fibrosis. Early identification and prevention of oxidative stress and ROS can contribute to reduced cystic kidney disease progression and improved longitudinal patient outcomes. Increased research regarding biomarkers, the pathophysiology of oxidative stress, and novel therapeutic interventions alongside the creation of comprehensive guidelines establishing methods of assessment, monitoring, and intervention for oxidative stress in cystic kidney disease patients is imperative to standardize clinical practice and improve patient outcomes. The integration of artificial intelligence (AI), genetic editing, and genome sequencing could further improve the early detection and management of cystic kidney disease and mitigate adverse patient outcomes. In this review, we aim to comprehensively assess the multifactorial role of ROS in cystic kidney disease, analyzing its pathophysiology, clinical outcomes, treatment interventions, clinical trials, animal models, and future directions for patient care.

Identification of SikCDPK family genes to low-temperature by RNA-seq approaches and functional analysis of SikCDPK1 in Saussurea involucrata (Kar. & Kir.).

Calcium-Dependent Protein Kinases (CDPKs) are a class of serine/threonine protein kinases encoded by several gene families that play key roles in biotic and abiotic stresses response and plant growth and development. However, snow lotus (Saussurea involucrata kar L.) CDPKs has rarely been reported. In this study, 20 CDPK genes in snow lotus were identified based on transcriptome data and classified into four groups (I-IV) based on their structural features and phylogenetic analyses. Among them, the transcript levels of SikCDPK1 were significantly induced by low temperature and multiple hormone treatments, and SikCDPK1 gene was found to have different expression in snow lotus seeds, leaves, stems and roots. The full-length promoter activity of SikCDPK1 gene was higher than that of the 5' end deletion fragment, and the promoter fragment containing the low temperature inducing element had increased activation after low temperature treatment. The promoter activity of SikCDPK1 gene was mainly expressed in roots and rosette leaves. In addition, overexpressing plants of SikCDPK1 were more tolerant compared to the wild type after being subjected to low temperature stress. Physiological analyses indicated that SikCDPK1 improved plant tolerance to low temperature stress by maintaining cell membrane stability and reducing the accumulation of reactive oxygen species (ROS). These findings provided insights into CDPK gene families in snow lotus and broaden our understanding of the biological role of SikCDPK1 and the mechanism of low temperature stress tolerance in snow lotus.

Comparative study of Tris Turmeric, Tris Turmeric Dimethyl Sulfoxide and Tris Turmeric Ethylene glycol extenders on the cryosurvivability, sperm resistance, in- vivo fertility and antioxidant status in buffalo bull semen

The freeze-thaw process leads to structural and functional damage due to excessive accumulation of reactive oxygen species (ROS). The addition of exogenous antioxidants to sperm diluents is of great importance to overcome oxidative damage during freezing. The purpose of this study was to explore the effects of three diluents Tris Turmeric, Tris Turmeric Dimethyl Sulfoxide and Tris Turmeric Ethylene glycol on the cold survival ability of buffalo sperm. Semen was collected from five local adult male buffalo breeds. A base diluent of Tris-citric acid-fructose (TCF) was prepared, adding 20% whole egg yolk (TCFY). The Tris extender without turmeric, without DMSO, and without EG was kept as a control. Other extenders are Tris containing turmeric TT (100 ml/5 ml Tris), Tris containing turmeric dimethyl sulfoxide TTD (100 ml/5 ml Tris + 1.5% DMSO) and Tris containing turmeric and ethylene glycol TTE EG (100 ml/5 ml Tris + 1.5% EG). Semen samples were added and a pure sperm concentration of 60 × 106/ml was achieved. Frozen buffalo sperm after thawing showed significant improvements in all research parameters of the three breeding samples compared to the control. Tris Turmeric Ethylene was the type that best improved sperm survival under frozen conditions, followed by Tris Turmeric and Tris Turmeric Dimethyl Sulfoxide compared to the control. A significant decrease in sperm motility after thawing was evident as usage time increased in all expanders. There was a significant increase in total antioxidant content (TAC) and insignificant change in malondialdehyde (MDA) of the diluent used compared to the control. Conception rate (CR) was higher in Tris Turmeric Ethylene glycol (65.2%), followed by Tris Turmeric (60.3%) and Tris Turmeric Dimethyl Sulfoxide (55.9%) compared to the control (36, 7%). It can be concluded that Tris Turmeric Ethylene Glycol is considered the best agent for improving cold survival and sperm fertility, followed by Tris Turmeric and Tris Turmeric Dimethyl Sulfoxide.

Isovalerylspiramycin I suppresses small cell lung cancer proliferation via ATR/CHK1 mediated DNA damage response and PERK/eIF2α/ATF4/CHOP mediated ER stress

Small cell lung cancer (SCLC) urgently needs new therapeutic approaches. We found that the antibiotic-derived compound Isovalerylspiramycin I (ISP-I) has potent anti-tumor activity against SCLC cell lines H1048 and DMS53 both in vitro and in vivo. ISP-I induced apoptosis, G2/M phase cell cycle arrest, and mitochondrial respiratory chain dysfunction in both cell lines. Comprehensive RNA sequencing revealed that the anti-SCLC effects of ISP-I were primarily attributed to ATR/CHK1-mediated DNA damage response and PERK/eIF2α/ATF4/CHOP-mediated ER stress. Importantly, the induction of DNA damage, ER stress, and apoptosis by ISP-I was mitigated by the reactive oxygen species (ROS) scavenger N-acetyl-L-cysteine (NAC), underscoring the critical role of ROS in the anti-SCLC mechanism of ISP-I. Moreover, ISP-I treatment induced immunogenic cell death (ICD) in SCLC cells, as evidenced by increased adenosine triphosphate (ATP) secretion, elevated release of high-mobility group box 1 (HMGB1), and enhanced exposure of calreticulin (CRT) on the cell surface. Additionally, network pharmacology analysis, combined with cellular thermal shift assay (CETSA) and cycloheximide (CHX) chase experiments, demonstrated that ISP-I acted as a ligand for apurinic/apyrimidinic endonuclease 1 (APEX1) and promoted its degradation, leading to the accumulation of ROS. In conclusion, our findings elucidate the multifaceted mechanisms underlying the anti-cancer effects of ISP-I, highlighting its potential as a promising therapeutic candidate for SCLC treatment.

2D MXene Nanosheets with ROS Scavenging Ability Effectively Delay Osteoarthritis Progression.

MXenes nanosheets with high conductivity, hydrophilicity, and excellent reactive oxygen species (ROS) scavenging ability have shown promise in treating various degenerative diseases correlated with abnormal ROS accumulation. Herein, the therapeutic potential of Ti3C2Tx nanosheets, which is the most widely investigated MXene material, in delaying osteoarthritis (OA) progression is demonstrated. In vitro experiments indicate the strong ROS scavenging capacity of Ti3C2Tx nanosheets and their acceptable biocompatibility. Ti3C2Tx nanosheets effectively protect chondrocytes from cell death induced by oxidative stress. In addition, Ti3C2Tx nanosheets demonstrate a prominent anti-inflammatory effect and the ability to restore homeostasis between anabolic activities and catabolic activities in chondrocytes. Furthermore, RNA sequencing reveals the potential mechanism underlying the Ti3C2Tx nanosheet-mediated therapeutic effect. Finally, the in vivo curative effect of Ti3C2Tx nanosheets is verified using a rat OA model. Histological staining and immunohistochemical analyses indicate that Ti3C2Tx nanosheets effectively ameliorate OA progression. Conclusively, the in vitro and in vivo experiments suggest that Ti3C2Tx nanosheets could be a promising and effective option for OA treatment.

Ternary inulin hydrogel with long-term intestinal retention for simultaneously reversing IBD and its fibrotic complication.

Excessive accumulation of reactive oxygen and nitrogen species (RONS) and dysbiosis of intestinal microbiota are pivotal symptoms for inflammatory bowel disease (IBD) and its associated complications, such as intestinal fibrosis. This research introduces a probiotic inulin hydrogel loaded with polypyrrole (PPy) nanozymes and antifibrotic drug pirfenidone (PFD) (PPy/PFD@Inulin gel) designed for the concurrent amelioration of IBD and its fibrotic complication. Upon oral administration, the inulin gel matrix could extend the gastrointestinal residence time of PPy nanozymes and PFD, facilitating the efficient reduction of pro-inflammatory cytokine levels and enhancement of the intestinal epithelial barrier repair as well as the suppression of intestinal fibrosis through sustained RONS scavenging, modulation of gut microbiota and attenuation of the TGF-β/Smad signaling pathway to inhibit fibroblast proliferation. Notably, the PPy/PFD@Inulin gel demonstrated significant prophylactic and therapeutic efficacy in acute and chronic colitis as well as intestinal fibrosis induced by dextran sodium sulfate (DSS) in mouse models. Thus, the engineered ternary PPy/PFD@Inulin gel offered a pioneered paradigm for simultaneous reversal of IBD and its associated complications, such as intestinal fibrosis, in a single therapeutic regimen.

Albiflorin inhibits osteoclastogenesis and titanium particles-induced osteolysis via inhibition of ROS accumulation and the PI3K/AKT signaling pathway

Periprosthetic osteolysis (PPO), caused by wear particles, is a significant complication of total joint replacement, leading to prosthesis failure. Previous research has highlighted the crucial role of osteoclast-induced bone destruction in PPO progression. Albiflorin (AF), a monoterpene glycoside from Paeonia lactiflora, is a key active ingredient known for its antioxidant and anti-inflammatory properties. Although AF has shown promise in treating various conditions, its impact on osteoclasts and PPO remains unexplored. Our study revealed that AF could effectively inhibit osteoclast differentiation to reduce overactivated bone resorption and effectively inhibit the accumulation of reactive oxygen species (ROS) induced by wear particles. In vitro experiments also confirmed that AF could effectively inhibit the PI3K/AKT signaling pathway and inhibit inflammation to regulate osteoclast generation. Studies in animal models have also verified the antioxidant and anti-inflammatory properties of AF. In summary, the above studies indicate that AF inhibits osteoclastogenesis via inhibiting ROS accumulation and the PI3K/AKT signaling pathway, which may be a potential therapeutic method for PPO.

Inhibition of calpain reduces oxidative stress and attenuates pyroptosis and ferroptosis in Clostridium perfringens Beta-1 toxin-induced macrophages

Clostridium perfringens Beta-1 toxin (CPB1) is a lethal toxin, which can lead to necrotic enteritis, but the pathological mechanism has not been elucidated. We investigated whether reactive oxygen species (ROS) participated in CPB1-induced pyroptosis and ferroptosis, and investigated the effects of calpain on CPB1-induced oxidative stress and inflammation. Scavenging ROS by N-acetyl cysteine (NAC) led to the reduction of ROS, inhibited the death of macrophages, cytoplasmic swelling and membrane rupture, the expression of pyroptosis-related proteins and proinflammatory factor, while increased the expression of anti-inflammatory factors in cells treated with rCPB1. Adenosine triphosphate (ATP) synthase, H+ transporting, mitochondrial F1 complex, alpha subunit 1 (ATP5A1) was identified specifically interact with rCPB1. Silencing ATP5A1 inhibited accumulation of ATP and ROS, leaded to less cytoplasmic swelling and membrane rupture, attenuated pyroptosis and inflammation in rCPB1-treated cells. We also found that rCPB1 induces ferroptosis in macrophages, and the level of ferroptosis was similar with H2O2. Of note, H2O2 is a major ROS source, indicated that ROS production may play a major role in the regulation of ferroptosis in macrophages treated with rCPB1. This finding was further corroborated in rCPB1- induced human acute monocytic leukemia cells, which were treated with NAC. In addition, the inhibition of ferroptosis using liproxstatin-1 inhibited the shriveled mitochondrial morphology, increased the expression of glutathione peroxidase 4, nicotinamide adenine dinucleotide (phosphate) hydrogen: quinone oxidoreductase 1 and cysteine/glutamic acid reverse transport solute carrier family 7 members 11, decreased the expression of heme oxygenase 1, nuclear receptor coactivator 4 and transferrin receptor proteins, reduced malondialdehyde and lipid peroxidation levels, and increased intracellular L-glutathione levels in cells treated with rCPB1. Furthermore, calpain inhibitor PD151746 was used to investigate how pyroptosis and ferroptosis were involved simultaneously in rCPB1-treated macrophages. We showed that PD151746 inhibited ATP and ROS production, reversed the representative pyroptosis/ferroptosis indicators and subsequently reduced inflammation. The above findings indicate that rCPB1 might lead to macrophage pyroptosis and ferroptosis through the large and sustained increase in intracellular calpain and oxidative stress, further lead to inflammation.

Nrf2 and Ferroptosis: Exploring Translational Avenues for Therapeutic Approaches to Neurological Diseases.

Nrf2, a crucial protein involved in defense mechanisms, particularly oxidative stress, plays a significant role in neurological diseases (NDs) by reducing oxidative stress and inflammation. NDs, including Alzheimer's, Parkinson's, Huntington's, amyotrophic lateral sclerosis, stroke, epilepsy, schizophrenia, depression, and autism, exhibit ferroptosis, iron-dependent regulated cell death resulting from lipid and iron-dependent reactive oxygen species (ROS) accumulation. Nrf2 has been shown to play a critical role in regulating ferroptosis in NDs. Age-related decline in Nrf2 expression and its target genes (HO-1, Nqo-1, and Trx) coincides with increased iron-mediated cell death, leading to ND onset. The modulation of iron-dependent cell death and ferroptosis by Nrf2 through various cellular and molecular mechanisms offers a potential therapeutic pathway for understanding the pathological processes underlying these NDs. This review emphasizes the mechanistic role of Nrf2 and ferroptosis in multiple NDs, providing valuable insights for future research and therapeutic approaches.

Reactive oxygen species-inducing itraconazole and its anti-biofilm activity against resistant Candida parapsilosis sensu lato biofilm cells isolated from patients with recalcitrant onychomycosis.

Candida parapsilosis was introduced as the second most responsible for nail involvement. The colonization of biotic and abiotic surfaces by Candida spp.can result in the formation of biofilms, which possess a high level of resistance to typical antifungal agents. Since Candida spp. can produce biofilm mass on the surface of the nails, dermatologists should consider appropriate antifungals to eliminate both the planktonic and biofilm cells. The aim of this research was to determine the antifungal efficacy of itraconazole against C. parapsilosis sensu lato biofilm formations, in addition to its static effects. Ten C. parapsilosis sensu lato isolates were enrolled in this study. The use of itraconazole results in the accumulation of reactive oxygen species (ROS) during treatment. In order to verify the correlation between ROS and itraconazole-induced cell death, the viability of cells was analyzed by administering the ROS scavenger Ascorbic acid. The apoptotic features of itraconazole were analyzed using the Annexin V-FITC method. Based on current data, it was found that the generation of intracellular stresses by itraconazole is not observed in cells upon ROS inhibition, emphasizing the importance of intracellular ROS in the apoptotic mechanism of itraconazole. Targeting the oxidative defense system is a powerful point to use ROS-inducing antifungals as a superior choice for more effective therapies in case of recalcitrant onychomycosis.

Facile Synthesis of Fe-Based Metal-Quinone Networks for Mutually Enhanced Mild Photothermal Therapy and Ferroptosis.

Mild photothermal therapy (MPTT) has emerged as a promising therapeutic modality for attenuating thermal damage to the normal tissues surrounding tumors, while the heat-induced upregulation of heat shock proteins (HSPs) greatly compromises the curative efficacy of MPTT by increasing cellular thermo-tolerance. Ferroptosis has been identified to suppress the overexpression of HSPs by the accumulation of lipid peroxides and reactive oxygen species (ROS), but is greatly restricted by overexpressed glutathione (GSH) in tumor microenvironment and undesirable ROS generation efficiency. Herein, a synergistic strategy based on the mutual enhancement of MPTT and ferroptosis is proposed for cleaving HSPs to recover tumor cell sensitivity. A facile method for fabricating a series of Fe-based metal-quinone networks (MQNs) by coordinated assembly is proposed and the representative FTP MQNs possess high photothermal conversion efficiency (69.3%). Upon 808 nm laser irradiation, FTP MQNs not only trigger effective MPTT to induce apoptosis but more significantly, potentiate Fenton reaction and marked GSH consumption to boost ferroptosis, and the reinforced ferroptosis effect in turn can alleviate the thermal resistance by declining the HSP70 defense and reducing ATP levels. This study provides a valuable rationale for constructing a large library of MQNs for achieving mutual enhancement of MPTT and ferroptosis.

FTH1P8 induces and transmits docetaxel resistance by inhibiting ferroptosis in prostate cancer

Overcoming docetaxel resistance remains a significant challenge in the management of prostate cancer. Previous studies have confirmed a link between ferroptosis and the development of docetaxel resistance. This study revealed that docetaxel-resistant prostate cancer cells presented increased FTH1P8 expression compared with docetaxel-sensitive cells. Decreasing the level of FTH1P8 counteracted docetaxel resistance and facilitated docetaxel-induced ferroptosis, which is characterized by an increase in intracellular Fe2+ concentration, lipid peroxidation levels (lipid ROS), reactive oxygen species (ROS) accumulation, malondialdehyde (MDA) production and mitochondrial damage, a decrease in the Fe3+ concentration and glutathione (GSH) content, and the ability to inhibit hydroxyl radical (·OH) and the mitochondrial membrane potential (MMP). Conversely, increasing the level of FTH1P8 had the opposite effect. A positive correlation was revealed between the expression of FTH1P8 and its parental gene FTH1 in prostate cancer tissues in The Cancer Genome Atlas (TCGA) database. Molecular investigations revealed that FTH1P8 expression increased through miR-1252–5p. Furthermore, rescue experiments confirmed that FTH1 mediated the inhibitory effect of FTH1P8 on ferroptosis. Moreover, FTH1P8 was discovered to play a role in the spread of docetaxel resistance via exosomes. Docetaxel-siRNA targeting FTH1P8 (siFTH1P8)-nanoliposomes (DOC-siFTH1P8-LIP), which can codeliver docetaxel and siFTH1P8, significantly inhibited docetaxel resistance in cells. These results indicated that FTH1P8 can function as both an indicator and a treatment target for docetaxel resistance. The use of DOC-siFTH1P8-LIP demonstrated promising therapeutic effects on docetaxel-resistant cells, suggesting a novel option for treating docetaxel-resistant prostate cancer.

Bacillus velezensis GH1-13 enhances drought tolerance in rice by reducing the accumulation of reactive oxygen species.

Plant growth-promoting rhizobacteria colonize the rhizosphere through dynamic and intricate interactions with plants, thereby providing various benefits and contributing to plant growth. Moreover, increasing evidence suggests that plant growth-promoting rhizobacteria affect plant tolerance to abiotic stress, but the underlying molecular mechanisms remain largely unknown. In this study, we investigated the effect of Bacillus velezensis strain GH1-13 on drought stress tolerance in rice. Phenotypical analysis, including the measurement of chlorophyll content and survival rate, showed that B. velezensis GH1-13 enhances rice tolerance to drought stress. Additionally, visualizing ROS levels and quantifying the expression of ROS-scavenging genes revealed that GH1-13 treatment reduces ROS accumulation under drought stress by activating the expression of antioxidant genes. Furthermore, the GH1-13 treatment stimulated the jasmonic acid response, which is a key phytohormone that mediates plant stress tolerance. Together with the result that jasmonic acid treatment promotes the expression of antioxidant genes, these findings indicate that B. velezensis GH1-13 improves drought tolerance in rice by reducing ROS accumulation and suggest that activation of the jasmonic acid response is deeply involved in this process.

The combined toxicity of polystyrene microplastic and arsenate: From the view of biochemical process in wheat seedlings (Triticum aestivum L.)

Microplastics (MPs) are important carriers of various toxic metals and can alter their toxicity pattern in agricultural soil, leading to combined pollution, therefore posing new challenges to soil pollution management and environmental risk assessment. In this study, we observed the internalization of MPs in plants and conducted incubation experiments to evaluated the effects of arsenate (As(V)) alone and in combination with polystyrene (PS) MPs on wheat seedlings (Triticum aestivum L.). Under As(V) alone and combined with PS-MP exposure, dose-dependent toxicity in terms of root and stem elongation and biomass accumulation was observed. Compared with As(V) alone, the presence of PS-MPs reduced the accumulation of As in wheat roots by 11.43–58.91%, but PS-MPs intensified the transport of As to the aboveground parts of wheat, increasing As accumulation in wheat stems by 27.77–1011.54%. This causes more serious mechanical damage and oxidative stress to plant cells, increasing the accumulation of reactive oxygen species and lipid peroxidation in wheat roots and upregulating the activities of antioxidant enzymes such as superoxide dismutase (SOD) and peroxidase (POD). In addition, the co-exposure of As(V) and PS-MPs disrupts the photosynthetic system of wheat leaves and the secretion activities of roots. Therefore, the combination of As(V) and PS-MPs caused greater damage to wheat growth. Our findings contribute to a more comprehensive assessment of the combined toxicity of MPs and heavy metal to crops.

Difference in the toxic effects of micro and nano ZnO particles on L. minor - an integrative approach.

The toxicity of nano-sized ZnO particles (nZnO) was evaluated and compared to that of their micro-sized counterparts (mZnO) using an integrative approach to investigate the mechanism of toxicity, utilizing duckweed (Lemna minor) as plant model. Following 7days of exposure to nZnO or mZnO (2.5, 5, 25, and 50mg L-1) growth rate, photosynthesis, oxidative stress, and genotoxicity parameters have been determined in duckweed. Phytotoxicity of both ZnO forms at relatively low concentrations was due to the release of free Zn ions into the nutrient media. However, the accumulation of Zn in plants treated with nZnO was significantly higher than in those treated with mZnO. Both mZnO and nZnO significantly reduced growth rate and impaired the functionality of the photosynthetic apparatus as evidenced by structural changes of chloroplasts, a decline in the efficiency of photosystem II, and chlorophyll a content. Additionally, exposure to mZnO and nZnO resulted in the accumulation of reactive oxygen species (ROS), increased lipid peroxidation, the formation of carbonylated proteins, DNA damage, and alterations in antioxidant defense mechanisms. Overall, nZnO caused significantly stronger toxic effects than mZnO. The mechanism of nZnO toxicity to L. minor, as determined by multivariate statistical analysis, involved the disruption of primary photosynthetic reactions due to a redox imbalance in the cell caused by the enhanced absorption of Zn into plant tissues.

Melatonin Treatment Alleviates Chilling Injury of Loquat Fruit via Modulating ROS Metabolism.

Cold storage is one of the most effective methods to maintain postharvest fruit quality. However, loquat fruits are prone to chilling injury (CI) during cold storage, appearing as symptoms such as browning and pitting, which leads to quality deterioration and economic losses. In this study, the effects of melatonin on CI alleviation and the potential role of reactive oxygen species (ROS) metabolism in loquat fruit were investigated. The results showed that 50 μM melatonin was the optimal concentration to inhibit the increase in CI index and cell membrane permeability. Moreover, compared to control fruits, 50 μM melatonin inhibited the malonaldehyde (MDA) content, O2-. production rate and H2O2 content (ROS accumulation) by 17.8%, 7.2% and 11.8%, respectively, during cold storage. Compared to non-treated loquats, 50 μM melatonin maintained higher levels of 1-diphenyl-2-picrylhydrazyl radical-scavenging ability and reducing power, as well as the contents of ascorbic acid (AsA) and glutathione (GSH). Additionally, 50 μM melatonin enhanced the activities of antioxidant enzymes, such as superoxide dismutase (SOD), catalase (CAT) and ascorbate peroxidase (APX) by increasing relevant gene expressions. The activities of SOD, CAT and APX were increased by up to 1.1-, 1.1- and 1.1-times (16 d) by melatonin, as compared with the control fruits. These findings indicate that melatonin mitigation of CI is involved in maintaining cellular redox apphomeostasis in loquat fruit during cold storage.

A GDSL motif-containing lipase modulates Sclerotinia sclerotiorum resistance in Brassica napus.

Sclerotinia stem rot (SSR) caused by Sclerotinia sclerotiorum (Lib.) De Bary is a devastating disease infecting hundreds of plant species. It also restricts the yield, quality, and safe production of rapeseed (Brassica napus) worldwide. However, the lack of resistance sources and genes to S. sclerotiorum has greatly restricted rapeseed SSR-resistance breeding. In this study, a previously identified GDSL motif-containing lipase gene, Brassica napus GDSL LIPASE-LIKE 1 (BnaC07.GLIP1), encoding a protein localized to the intercellular space, was characterized as functioning in plant immunity to S. sclerotiorum. The BnaC07.GLIP1 promoter is S. sclerotiorum-inducible and the expression of BnaC07.GLIP1 is substantially enhanced after S. sclerotiorum infection. Arabidopsis (Arabidopsis thaliana) heterologously expressing and rapeseed lines overexpressing BnaC07.GLIP1 showed enhanced resistance to S. sclerotiorum, whereas RNAi suppression and CRISPR/Cas9 knockout B. napus lines were hyper-susceptible to S. sclerotiorum. Moreover, BnaC07.GLIP1 affected the lipid composition and induced the production of phospholipid molecules, such as phosphatidylethanolamine, phosphatidylcholine and phosphatidic acid, which were correlated with decreased levels of reactive oxygen species (ROS) and enhanced expression of defense-related genes. A B. napus bZIP44 transcription factor specifically binds the CGTCA motif of the BnaC07.GLIP1 promoter to positively regulate its expression. BnbZIP44 responded to S. sclerotiorum infection, and its heterologous expression inhibited ROS accumulation, thereby enhancing S. sclerotiorum resistance in Arabidopsis. Thus, BnaC07.GLIP1 functions downstream of BnbZIP44 and is involved in S. sclerotiorum resistance by modulating the production of phospholipid molecules and ROS homeostasis in B. napus, providing insights into the potential roles and functional mechanisms of BnaC07.GLIP1 in plant immunity and for improving rapeseed SSR disease-resistance breeding.

The transcription factor RppA regulates chlorophyll and carotenoid biosynthesis to improve photoprotection in cyanobacteria.

Chlorophyll is an essential photosynthetic pigment but also a strong photosensitizer. Excessive free chlorophyll and its precursors can cause oxidative damage to photosynthetic organisms. Cyanobacteria are the oldest oxygenic photosynthetic organisms and the ancestors of the chloroplast. Owing to their complex habitats, cyanobacteria require precise regulation of chlorophyll synthesis to respond to environmental factors, especially changes in light. Chlorophyll synthase, encoded by chlG, is the enzyme catalyzing the final step of chlorophyll biosynthesis, which is closely related to photosynthesis biogenesis. However, the transcriptional regulation on chlG remains unclear. Here, the transcription factor, regulator of photosynthesis and photopigment-related gene expression A (RppA) was identified to bind to the chlG promoter by screening a yeast one-hybrid library in the cyanobacterium Synechocystis sp. PCC 6803. The rppA knock-out mutant showed a phenotype of slow growth and severe oxidative damage under dark-light transition conditions. The up-regulated transcriptional expression of chlG was significantly higher and more chlorophyll and its precursors accumulated in the rppA knock-out mutant than those in the wild-type strain during the transition from darkness to light, indicating RppA represses the expression of chlG in Synechocystis. Meanwhile, RppA could synchronously promote the transcription of carotenoids biosynthesis-related genes to enhance carotenoids synthesis during the dark-light transition. These results reveal synergistic regulation of chlorophyll and carotenoids biosynthesis in cyanobacteria in response to frequent dark-light transitions, which slows down chlorophyll biosynthesis while promoting carotenoids biosynthesis to avoid oxidative damage caused by excessive reactive oxygen species accumulation.

Dihydrotestosterone induces reactive oxygen species accumulation and mitochondrial fission leading to apoptosis of granulosa cells

Dihydrotestosterone (DHT), which has significant androgenic activity，is a major player in follicle development and ovary function in females. However, an excess of androgens may result in increased follicular apoptosis with adverse effects on female fertility. This study aimed to explore the mechanism by which DHT induces apoptosis in human ovarian granulosa cells (GCs). The association between DHT and GC apoptosis was explored by the construction of rat models of polycystic ovary syndrome (PCOS). It was found that serum DHT levels were negatively correlated with thickness of the GC layer in PCOS model rats (R2=0.8342, p＜0.0001), compared with control rats, together with significant increases in cofactors (Fis1: p=0.008; MFF: p=0.044). The GC SVOG cell line was used to clarify the mechanism by which DHT influenced GC apoptosis in in vitro experiments. The results confirmed that apoptosis in SVOG cells was positively associated with the DHT dose. The expression of the autophagy-related proteins LC3A/B (p=0.027) and the proapoptotic protein Bax (p=0.0095) were increased, while that of the anti-apoptotic protein Bcl-2 (p=0.0005) was decreased in the high-dose DHT group. ROS levels were significantly increased (p=0.0237) and the mitochondrial membrane potential ΔΨm was decreased (p=0.0194). Moreover, ultrastructural analysis of the mitochondria indicated significant damage. The results of RT-qPCR and western blotting showed that two fission cofactor-Fis1（p=0.034） and MFF (p=0.039) were significantly increased after treatment with high doses of DHT. Even though the overall expression of Drp1 did not change significantly (p=0.5961), that of activated Phosphor-Drp1(Ser616) was significantly increased (p=0.046), while the expression of Phosphor-Drp1 (Ser637) was markedly reduced (p=0.007) following exposure to high concentrations of DHT. All these effects could be reversed by the Drp1 inhibitor Mdivi-1. These findings indicated the impact of DHT on ROS aggregation and mitochondrial fission, resulting in GC apoptosis. An imbalance in Drp1 phosphorylation may be the key link in DHT-induced excessive mitochondrial fission.