Oxidative stress increased respiration and generation of reactive oxygen species, resulting in ATP depletion, opening of mitochondrial permeability transition, and programmed cell death

Unravelling the role of WRKY transcription factors in leaf senescence: Genetic and molecular insights

BACKGROUND

Leaf senescence (LS), the final phase in leaf development, is an important and precisely regulated process crucial for plant well-being and the redistribution of nutrients. It is intricately controlled by various regulatory factors, including WRKY transcription factors (TFs). WRKYs are one of the most significant plant TF families, and several of them are differentially regulated and important during LS. Recent research has enhanced our understanding of the structural and functional characteristics of WRKY TFs, providing insights into their regulatory roles.

AIM OF REVIEW

This review aims to elucidate the genetic and molecular mechanisms underlying the intricate regulatory networks associated with LS by investigating the role of WRKY TFs. We seek to highlight the importance of WRKY-mediated signaling pathways in understanding LS, plant evolution, and response to varying environmental conditions.

KEY SCIENTIFIC CONCEPTS OF REVIEW

WRKY TFs exhibit specific DNA-binding activity at the N-terminus and dynamic interactions of the intrinsically disordered domain at the C-terminus with various proteins. These WRKY TFs not only control the activity of other WRKYs, but also interact with either WRKYs or other TFs, thereby fine- tuning the expression of target genes. By unraveling the complex interactions and regulatory mechanisms of WRKY TFs, this review broadens our knowledge of the genetic and molecular basis of LS. Understanding WRKY-mediated signalling pathways provides crucial insights into specific aspects of plant development, such as stress-induced senescence, and offers potential strategies for improving crop resilience to environmental stresses like drought and pathogen attacks. By targeting these pathways, it may be possible to enhance specific productivity traits, such as increased yield stability under adverse conditions, thereby contributing to more reliable agricultural outputs.

Seasonal dynamics in microbial trace metals transporters during phytoplankton blooms in the Southern Ocean

Trace metals are required as cofactors in metalloproteins that are essential in microbial metabolism and growth. The microbial requirements of diverse metals and the capabilities of prokaryotic taxa to acquire these metals remain poorly understood. We present here results from metagenomic observations over an entire productive season in the region off Kerguelen Island (Indian Sector of the Southern Ocean). We observed seasonal patterns in the abundance of prokaryotic transporters of seven trace elements (zinc [Zn], manganese [Mn], nickel [Ni], molybdenum [Mo], tungsten [W], copper [Cu] and cobalt [Co]) and the consecutive spring and summer phytoplankton blooms were strong drivers of these temporal trends. Taxonomic affiliation of the functional genes revealed that Rhodobacteraceae had a broad repertoire of trace metal transporters (Mn, Zn, Ni, W and Mo) and a more restricted set was observed for other prokaryotic groups, such as Flavobacteriaceae (Zn), Nitrincolaceae (Ni and W) and Thioglobaceae (Mo). The prevalence of trace metal transporters within a prokaryotic group, as determined on the family level, was overall confirmed in representative metagenome-assembled genomes. We discuss the potential involvement of prokaryotic groups in processes related to organic matter utilisation that require these metals and the consequences on carbon and trace metal cycling in surface waters of the Southern Ocean.

The role of redox-active small molecules and oxidative protein post-translational modifications in seed aging

Seed vigor is a crucial indicator of seed quality. Variations in seed vigor are closely associated with seed properties and storage conditions. The vigor of mature seeds progressively declines during storage, which is called seed deterioration or aging. Seed aging induces a cascade of cellular damage, including impaired subcellular structures and macromolecules, such as lipids, proteins, and DNA. Reactive oxygen species (ROS) act as signaling molecules during seed aging causing oxidative damage and triggering programmed cell death (PCD). Mitochondria are the main site of ROS production and change morphology and function before other organelles during aging. The roles of other small redox-active molecules in regulating cell and seed vigor, such as nitric oxide (NO) and hydrogen sulfide (H2S), were identified later. ROS, NO, and H2S typically regulate protein function through post-translational modifications (PTMs), including carbonylation, S-glutathionylation, S-nitrosylation, and S-sulfhydration. These signaling molecules as well as the PTMs they induce interact to regulate cell fate and seed vigor. This review was conducted to describe the physiological changes and underlying molecular mechanisms that in seed aging and provides a comprehensive view of how ROS, NO, and H2S affect cell death and seed vigor.

Mechanisms of Litchi Response to Postharvest Energy Deficiency via Energy and Sugar Metabolisms

In the post-harvest phase, fruit is inexorably subjected to extrinsic stressors that expedite energy expenditure and truncate the storage lifespan. The present study endeavors to elucidate the response strategies of litchi to the alterations of energy state caused by 2,4-Dinitrophenol (DNP) treatment through energy metabolism and sugar metabolism. It was observed that the DNP treatment reduced the energy state of the fruit, exacerbated membrane damage and triggered rapid browning in the pericarp after 24 h of storage. Furthermore, the expression of genes germane to energy metabolism (LcAtpB, LcAOX1, LcUCP1, LcAAC1, and, LcSnRK2) reached their peak within the initial 24 h of storage, accompanied by an elevation in the respiratory rate, which effectively suppressed the rise in browning index of litchi pericarp. The study also posits that, to cope with the decrease of energy levels and membrane damage, litchi may augment the concentrations of fructose, glucose, inositol, galactose, and sorbose, thus safeguarding the canonical metabolic functions of the fruit. Collectively, these findings suggest that litchi can modulate energy and sugar metabolism to cope with fruit senescence under conditions of energy deficiency. This study significantly advances the understanding of the physiological responses exhibited by litchi fruit to post-harvest external stressors.

Combined effects of three insecticides with different modes of action on biochemical responses of the solitary bee Osmia bicornis

Bees are simultaneously exposed to a variety of pesticides, which are often applied in mixtures and can cause lethal and sublethal effects. The combined effects of pesticides, however, are not measured in the current risk assessment schemes. Additionally, the sublethal effects of pesticides on a variety of physiological processes are poorly recognized in bees, especially in non-Apis solitary bees. In this study, we used a full-factorial design to examine the main and interactive effects of three insecticide formulations with different modes of action (Mospilan 20 SP, Sherpa 100 EC, and Dursban 480 EC) on bee biochemical processes. We measured acetylcholinesterase (AChE), glutathione S-transferase (GST) and esterase (EST) activities, as well as a nonenzymatic biomarker associated with energy metabolism, i.e., ATP level. All studied endpoints were affected by Sherpa 100 EC, and the activities of AChE and EST as well as ATP levels were affected by Dursban 480 EC. Moreover, complex interactions between all three insecticides affected ATP levels, showing outcomes that cannot be predicted when testing each insecticide separately. The results indicate that even if interactive effects are sometimes difficult to interpret, there is a need to study such interactions if laboratory-generated toxicity data are to be extrapolated to field conditions.

Identification of Drought-Resistant Response in Proso Millet (Panicum miliaceum L.) Root through Physiological and Transcriptomic Analysis

Proso millet (Panicum miliaceum L.) is resilient to abiotic stress, especially to drought. However, the mechanisms by which its roots adapt and tolerate salt stress are obscure. In this study, to clarify the molecular mechanism of proso millet in response to drought stress, the physiological indexes and transcriptome in the root of seedlings of the proso millet cultivar 'Yumi 2' were analyzed at 0, 0.5, 1.0, 1.5, and 3.0 h of stimulated drought stress by using 20% PEG-6000 and after 24 h of rehydration. The results showed that the SOD activity, POD activity, soluble protein content, MDA, and O2-· content of 'Yumi 2' increased with the time of drought stress, but rapidly decreased after rehydration. Here, 130.46 Gb of clean data from 18 samples were obtained, and the Q30 value of each sample exceeded 92%. Compared with 0 h, the number of differentially expressed genes (DEGs) reached the maximum of 16,105 after 3 h of drought, including 9153 upregulated DEGs and 6952 downregulated DEGs. Gene Ontology and Kyoto Encyclopedia of Genes and Genomes pathway analyses revealed that upregulated DEGs were mainly involved in ATP binding, nucleus, protein serine/threonine phosphatase activity, MAPK signaling pathway-plant, plant-pathogen interactions, and plant hormone signal transduction under drought stress, while downregulated DEGs were mainly involved in metal ion binding, transmembrane transporter activity, and phenylpropanoid biosynthesis. Additionally, 1441 TFs screened from DEGs were clustered into 64 TF families, such as AP2/ERF-ERF, bHLH, WRKY, NAC, MYB, and bZIP TF families. Genes related to physiological traits were closely related to starch and sucrose metabolism, phenylpropanoid biosynthesis, glutathione metabolism, and plant hormone signal transduction. In conclusion, the active oxygen metabolism system and the soluble protein of proso millet root could be regulated by the activity of protein serine/threonine phosphatase. AP2/ERF-ERF, bHLH, WRKY, NAC, MYB, and bZIP TF families were found to be closely associated with drought tolerance in proso millet root. This study will provide data to support a subsequent study on the function of the drought tolerance gene in proso millet.

Mitochondrial-Stem Cell Connection: Providing Additional Explanations for Understanding Cancer

The cancer paradigm is generally based on the somatic mutation model, asserting that cancer is a disease of genetic origin. The mitochondrial-stem cell connection (MSCC) proposes that tumorigenesis may result from an alteration of the mitochondria, specifically a chronic oxidative phosphorylation (OxPhos) insufficiency in stem cells, which forms cancer stem cells (CSCs) and leads to malignancy. Reviewed evidence suggests that the MSCC could provide a comprehensive understanding of all the different stages of cancer. The metabolism of cancer cells is altered (OxPhos insufficiency) and must be compensated by using the glycolysis and the glutaminolysis pathways, which are essential to their growth. The altered mitochondria regulate the tumor microenvironment, which is also necessary for cancer evolution. Therefore, the MSCC could help improve our understanding of tumorigenesis, metastases, the efficiency of standard treatments, and relapses.

DDT exposure induces tremor-like behavior and neurotoxicity in developmental stages of embryonic zebrafish

Dichlorodiphenyltrichloroethane (DDT) is a broad-spectrum insecticide, widely detected in environments due to its high stability characteristic and long natural half-life period. The adverse impact of DDT exposure on organisms and humans has attracted great concern worldwide. The current study explored the developmental and neurobehavioral toxicity response of DDT in embryonic zebrafish. The embryos were treated with DDT (0, 0.1, 1, 2.5 and 5 µM) during 6 h post fertilization (hpf) to 144 hpf. Our result indicated that DDT exposures increased the embryo hatching rate at 48 and 60 hpf, the larval malformation rate at 120 hpf and mortality rate at 144 hpf. The manifested malformations included uninflated swim bladder, bent spine and tail, deformed liver, and pericardial edema. The 120 hpf larval organs size of the gut and swim bladder was decreased in higher exposed concentration groups. Besides, DDT exposure resulted in hyperactivity for the embryo spontaneous movement at 24 hpf and tremor like movement measured by the free larval activity at 72 hpf, as well as the larval activity at 96 hpf under light-dark transition stimulus. Mechanistic examinations at 120 hpf revealed DDT exposure elevated oxidative stress through MDA formation increase, ATP level decrease as well as antioxidant enzyme genes (sod1 and gpx1a) expression decrease. DDT exposure induced abnormal neurotransmitters expression with DA level increase, 5-HT and NOS level decrease. DDT exposure suppressed the gene expressions involved in axon development (rab33a and nrxn2a) and potassium channel (kcnq2 and kcnq3). Our results suggest that the hyperactivity and tremor like movement in DDT-exposed embryos/larvae may result from oxidative stress involved with neuronal damage.

Cold atmospheric plasma sensitizes head and neck cancer to chemotherapy and immune checkpoint blockade therapy

Head and neck cancer (HNC) is the seventh most prevalent cancer globally, often characterized by chemo-resistance and immunosuppression, which significantly hampers treatment efficacy. Cold atmospheric plasma (CAP) has recently emerged as a promising adjuvant oncotherapy with substantial potential and advantages. In this study, Piezobrush® PZ2, a handheld CAP unit based on the piezoelectric direct discharge technology, was used to generate and deliver non-thermal plasma. We aimed to investigate the effects of CAPPZ2 on various types of HNC cells and elucidate the underlying mechanisms. In addition, we endeavored to examine the efficacy of combining CAPPZ2 with chemotherapy drugs (i.e., cisplatin) or immune checkpoint blockade (ICB, i.e., PD1 antibody) in HNC treatment. Firstly, the results demonstrated that CAPPZ2 exerted anti-neoplastic functions through inhibiting cell proliferation, migration and invasion, and promoting apoptosis and autophagy. Secondly, using transcriptomic sequencing, Western blotting, and quantitative real-time PCR, the mechanisms underlying CAPPZ2 treatment in vitro was presumed to be a multitargeted blockade of major cancer survival pathways, such as redox balance, glycolysis, and PI3K/AKT/mTOR/HIF-1α signaling. Lastly, combinatorial thearpy containing CAPPZ2 and cisplatin or PD-1 antibody significantly suppressed tumor growth and prolonged recipient survival in vivo. Collectively, the synergistic effects of CAPPZ2 and cisplatin or PD-1 antibody could serve as a promising solution to enhance head and neck tumor elimination.

Integrated Transcriptome and Metabolome Analysis Revealed the Causal Agent of Primary Bud Necrosis in 'Summer Black' Grape

Primary bud necrosis of grape buds is a physiological disorder that leads to decreased berry yield and has a catastrophic impact on the double cropping system in sub-tropical areas. The pathogenic mechanisms and potential solutions remain unknown. In this study, the progression and irreversibility patterns of primary bud necrosis in 'Summer Black' were examined via staining and transmission electron microscopy observation. Primary bud necrosis was initiated at 60 days after bud break and was characterized by plasmolysis, mitochondrial swelling, and severe damage to other organelles. To reveal the underlying regulatory networks, winter buds were collected during primary bud necrosis progression for integrated transcriptome and metabolome analysis. The accumulation of reactive oxygen species and subsequent signaling cascades disrupted the regulation systems for cellular protein quality. ROS cascade reactions were related to mitochondrial stress that can lead to mitochondrial dysfunction, lipid peroxidation causing damage to membrane structure, and endoplasmic reticulum stress leading to misfolded protein aggregates. All these factors ultimately resulted in primary bud necrosis. Visible tissue browning was associated with the oxidation and decreased levels of flavonoids during primary bud necrosis, while the products of polyunsaturated fatty acids and stilbenes exhibited an increasing trend, leading to a shift in carbon flow from flavonoids to stilbene. Increased ethylene may be closely related to primary bud necrosis, while auxin accelerated cell growth and alleviated necrosis by co-chaperone VvP23-regulated redistribution of auxin in meristem cells. Altogether, this study provides important clues for further study on primary bud necrosis.

Potential of algae-derived alginate oligosaccharides and β-glucan to counter inflammation in adult zebrafish intestine

Alginate oligosaccharides (AOS) are natural bioactive compounds with anti-inflammatory properties. We performed a feeding trial employing a zebrafish (Danio rerio) model of soybean-induced intestinal inflammation. Five groups of fish were fed different diets: a control (CT) diet, a soybean meal (SBM) diet, a soybean meal+β-glucan (BG) diet and 2 soybean meal+AOS diets (alginate products differing in the content of low molecular weight fractions - AL, with 31% < 3kDa and AH, with 3% < 3kDa). We analyzed the intestinal transcriptomic and plasma metabolomic profiles of the study groups. In addition, we assessed the expression of inflammatory marker genes and histological alterations in the intestine. Dietary algal β-(1, 3)-glucan and AOS were able to bring the expression of certain inflammatory genes altered by dietary SBM to a level similar to that in the control group. Intestinal transcriptomic analysis indicated that dietary SBM changed the expression of genes linked to inflammation, endoplasmic reticulum, reproduction and cell motility. The AL diet suppressed the expression of genes related to complement activation, inflammatory and humoral response, which can likely have an inflammation alleviation effect. On the other hand, the AH diet reduced the expression of genes, causing an enrichment of negative regulation of immune system process. The BG diet suppressed several immune genes linked to the endopeptidase activity and proteolysis. The plasma metabolomic profile further revealed that dietary SBM can alter inflammation-linked metabolites such as itaconic acid, taurochenodeoxycholic acid and enriched the arginine biosynthesis pathway. The diet AL helped in elevating one of the short chain fatty acids, namely 2-hydroxybutyric acid while the BG diet increased the abundance of a vitamin, pantothenic acid. Histological evaluation revealed the advantage of the AL diet: it increased the goblet cell number and length of villi of the intestinal mucosa. Overall, our results indicate that dietary AOS with an appropriate amount of < 3kDa can stall the inflammatory responses in zebrafish.

Transcriptome Analysis of the Late-Acting Self-Incompatibility Associated with RNase T2 Family in Camellia oleifera

The Camellia oil tree (Camellia oleifera Abel.) is an important nonwood forest species in China, and the majority of its cultivars are late-acting self-incompatibility (LSI) types. Although several studies have examined the mechanism of LSI, the process is quite complicated and unclear. In this study, pollen tube growth and fruit setting of two Camellia oil tree cultivars Huashuo (HS) and Huajin (HJ) were investigated after non and self-pollination, and transcriptomic analysis of the ovaries was performed 48 h after self-pollination to identify the potential genes implicated in the LSI of Camellia oil trees. The results showed that the fruit set of HS was significantly higher than that of HJ after self-pollination. Transcriptomic analysis revealed that plant hormone signal transduction, the phosphatidylinositol signaling system, ATP-binding cassette (ABC) transporters, reactive oxygen species (ROS) metabolism, and Ca2+ signaling were mainly contributed in the LSI of reaction of Camellia oil tree. Moreover, nine RNase T2 genes were identified from the transcriptome analysis, which also showed that CoRNase7 participated in the self-incompatibility reaction in HS. Based on phylogenetic analysis, CoRNase6 was closely related to S-RNase from coffee, and CoRNase7 and CoRNase8 were closely related to S-RNase from Camellia sinensis. The 9 RNase T2 genes successfully produced proteins in prokaryotes. Subcellular localization indicated that CoRNase1 and CoRNase5 were cytoplasmic proteins, while CoRNase7 was a plasma membrane protein. These results screened the main metabolic pathways closely related to LSI in Camellia oil tree, and SI signal transduction might be regulated by a large molecular regulatory network. The discovery of T2 RNases provided evidence that Camellia oil tree might be under RNase-based gametophytic self-incompatibility.

Hydrogen sulfide upregulates the alternative respiratory pathway in mangrove plant Avicennia marina to attenuate waterlogging-induced oxidative stress and mitochondrial damage in a calcium-dependent manner

Hydrogen sulfide (H₂ S) is considered to mediate plant growth and development. However, whether H₂ S regulates the adaptation of mangrove plant to intertidal flooding habitats is not well understood. In this study, sodium hydrosulfide (NaHS) was used as an H₂ S donor to investigate the effect of H₂ S on the responses of mangrove plant Avicennia marina to waterlogging. The results showed that 24-h waterlogging increased reactive oxygen species (ROS) and cell death in roots. Excessive mitochondrial ROS accumulation is highly oxidative and leads to mitochondrial structural and functional damage. However, the application of NaHS counteracted the oxidative damage caused by waterlogging. The mitochondrial ROS production was reduced by H₂ S through increasing the expressions of the alternative oxidase genes and increasing the proportion of alternative respiratory pathway in the total mitochondrial respiration. Secondly, H₂ S enhanced the capacity of the antioxidant system. Meanwhile, H₂ S induced Ca²⁺ influx and activated the expression of intracellular Ca²⁺ -sensing-related genes. In addition, the alleviating effect of H₂ S on waterlogging can be reversed by Ca²⁺ chelator and Ca²⁺ channel blockers. In conclusion, this study provides the first evidence to explain the role of H₂ S in waterlogging adaptation in mangrove plants from the mitochondrial aspect.

A deeply conserved protease, acylamino acid-releasing enzyme (AARE), acts in ageing in Physcomitrella and Arabidopsis

Reactive oxygen species (ROS) are constant by-products of aerobic life. In excess, ROS lead to cytotoxic protein aggregates, which are a hallmark of ageing in animals and linked to age-related pathologies in humans. Acylamino acid-releasing enzymes (AARE) are bifunctional serine proteases, acting on oxidized proteins. AARE are found in all domains of life, albeit under different names, such as acylpeptide hydrolase (APEH/ACPH), acylaminoacyl peptidase (AAP), or oxidized protein hydrolase (OPH). In humans, AARE malfunction is associated with age-related pathologies, while their function in plants is less clear. Here, we provide a detailed analysis of AARE genes in the plant lineage and an in-depth analysis of AARE localization and function in the moss Physcomitrella and the angiosperm Arabidopsis. AARE loss-of-function mutants have not been described for any organism so far. We generated and analysed such mutants and describe a connection between AARE function, aggregation of oxidized proteins and plant ageing, including accelerated developmental progression and reduced life span. Our findings complement similar findings in animals and humans, and suggest a unified concept of ageing may exist in different life forms.

The Effect of Necrosis Inhibitor on Dextran Sulfate Sodium Induced Chronic Colitis Model in Mice

Uncontrolled chronic inflammation and necrosis is characteristic of inflammatory bowel disease (IBD). This study aimed to investigate the effect of necrosis inhibitor (NI, NecroX-7) on a dextran sulfate sodium (DSS) induced chronic colitis model of mice. DSS was administered on days 1-5, and the NI was administered intraperitoneally (3 mg/kg, 30 mg/kg) on days 1, 3, and 5 as well as every other day during the first five days of a three-week cycle. Three cycles of administration were performed. Colitis was evaluated based on the disease activity index (DAI) score, colon length, and histological score. Reverse transcription polymerase chain reaction testing, the Western blot assay, and immunohistochemical staining were performed to determine inflammatory cytokine levels. The NI reduced body weight change and the DAI score. Colon length and the histological score were longer and lower in the NI-treated groups, respectively. The NI decreased the expression of pro-inflammatory cytokines, particularly in tumor necrosis factor alpha (TNF-α) and phosphorylated nuclear factor kappa B (p-NF-κB). Immunohistochemical staining revealed decreased inducible nitric oxide synthase (iNOS) and high mobility group box 1 (HMGB1) levels. Overall, the NI improved DSS induced chronic colitis by attenuating the mRNA expression of pro-inflammatory cytokines such as TNF-α. Therefore, NI use is a potential, novel treatment approach for IBD.

Biological autoluminescence as a perturbance-free method for monitoring oxidation in biosystems

Biological oxidation processes are in the core of life energetics, play an important role in cellular biophysics, physiological cell signaling or cellular pathophysiology. Understanding of biooxidation processes is also crucial for biotechnological applications. Therefore, a plethora of methods has been developed for monitoring oxidation so far, each with distinct advantages and disadvantages. We review here the available methods for monitoring oxidation and their basic characteristics and capabilities. Then we focus on a unique method - the only one that does not require input of additional external energy or chemicals - which employs detection of biological autoluminescence (BAL). We highlight the pros and cons of this method and provide an overview of how BAL can be used to report on various aspects of cellular oxidation processes starting from oxygen consumption to the generation of oxidation products such as carbonyls. This review highlights the application potential of this completely non-invasive and label-free biophotonic diagnostic method.

Trans-cinnamaldehyde-related overproduction of benzoic acid and oxidative stress on Arabidopsis thaliana

Introduction

Trans-cinnamaldehyde is a specialised metabolite that naturally occurs in plants of the Lauraceae family. This study focused on the phytotoxic effects of this compound on the morphology and metabolism of Arabidopsis thaliana seedlings.

Material and methods

To evaluate the phytotoxicity of trans-cinnamaldehyde, a dose-response curve was first performed for the root growth process in order to calculate the reference inhibitory concentrations IC50 and IC80 (trans-cinnamaldehyde concentrations inducing a 50% and 80% inhibition, respectively). Subsequently, the structure and ultrastructure of the roots treated with the compound were analysed by light and electron microscopy. Based on these results, the following assays were carried out to in depth study the possible mode of action of the compound: antiauxinic PCIB reversion bioassay, determination of mitochondrial membrane potential, ROS detection, lipid peroxidation content, hormone quantification, in silico studies and gene expression of ALDH enzymes.

Results

Trans-cinnamaldehyde IC50 and IC80 values were as low as 46 and 87 μM, reducing the root growth and inducing the occurrence of adventitious roots. At the ultrastructural level, the compound caused alterations to the mitochondria, which were confirmed by detection of the mitochondrial membrane potential. The morphology observed after the treatment (i.e., appearance of adventitious roots) suggested a possible hormonal mismatch at the auxin level, which was confirmed after PCIB bioassay and hormone quantification by GC-MS. The addition of the compound caused an increase in benzoic, salicylic and indoleacetic acid content, which was related to the increased gene expression of the aldehyde dehydrogenase enzymes that can drive the conversion of trans-cinnamaldehyde to cinnamic acid. Also, an increase of ROS was also observed in treated roots. The enzyme-compound interaction was shown to be stable over time by docking and molecular dynamics assays.

Discussion

The aldehyde dehydrogenases could drive the conversion of trans-cinnamaldehyde to cinnamic acid, increasing the levels of benzoic, salicylic and indoleacetic acids and causing the oxidative stress symptoms observed in the treated seedlings. This would result into growth and development inhibition of the trans-cinnamaldehyde-treated seedlings and ultimately in their programmed-cell-death.

Depletion plays a pivotal role in self-incompatibility, revealing a link between cellular energy status, cytosolic acidification and actin remodelling in pollen tubes

Self-incompatibility (SI) involves specific interactions during pollination to reject incompatible ('self') pollen, preventing inbreeding in angiosperms. A key event observed in pollen undergoing the Papaver rhoeas SI response is the formation of punctate F-actin foci. Pollen tube growth is heavily energy-dependent, yet ATP levels in pollen tubes have not been directly measured during SI. Here we used transgenic Arabidopsis lines expressing the Papaver pollen S-determinant to investigate a possible link between ATP levels, cytosolic pH ([pH]_cyt ) and alterations to the actin cytoskeleton. We identify for the first time that SI triggers a rapid and significant ATP depletion in pollen tubes. Artificial depletion of ATP triggered cytosolic acidification and formation of actin aggregates. We also identify in vivo, evidence for a threshold [pH]_cyt of 5.8 for actin foci formation. Imaging revealed that SI stimulates acidic cytosolic patches adjacent to the plasma membrane. In conclusion, this study provides evidence that ATP depletion plays a pivotal role in SI upstream of programmed cell death and reveals a link between the cellular energy status, cytosolic acidification and alterations to the actin cytoskeleton in regulating Papaver SI in pollen tubes.

Regulation of salt tolerance in the roots of Zea mays by L-histidine through transcriptome analysis

Soil salinization is an important worldwide environmental problem and the main reason to reduce agricultural productivity. Recent findings suggested that histidine is a crucial residue that influences the ROS reduction and improves the plants' tolerance to salt stress. Herein, we conducted experiments to understand the underlying regulatory effects of histidine on maize root system under salt stress (100 mM NaCl solution system). Several antioxidant enzymes were determined. The related expressed genes (DEGs) with its pathways were observed by Transcriptome technologies. The results of the present study confirmed that histidine can ameliorate the adverse effects of salt stress on maize root growth. When the maize roots exposed to 100 mM NaCl were treated with histidine, the accumulation of superoxide anion radicals, hydrogen peroxide, and malondialdehyde, and the content of nitrate nitrogen and ammonium nitrogen were significantly reduced; while the activities of superoxide dismutase, peroxidase, catalase, nitrate reductase, glutamine synthetase, and glutamate synthase were significantly increased. Transcriptome analysis revealed that a total of 454 (65 up-regulated and 389 down-regulated) and 348 (293 up-regulated and 55 down-regulated) DEGs were observed when the roots under salt stress were treated with histidine for 12 h and 24 h, respectively. The pathways analysis of those DEGs showed that a small number of down-regulated genes were enriched in phytohormone signaling and phenylpropanoid biosynthesis at 12 h after histidine treatment, and the DEGs involved in the phytohormone signaling, glycolysis, and nitrogen metabolism were significantly enriched at 24 h after treatment. These results of gene expression and enzyme activities suggested that histidine can improve the salt tolerance of maize roots by enriching some DEGs involved in plant hormone signal transduction, glycolysis, and nitrogen metabolism pathways.

Mitochondrial dysfunction associated with ascorbate synthesis in plants

Mitochondria are the major organelles of energy production; however, active mitochondria can decline their energetic role and show a dysfunctional status. Mitochondrial dysfunction was induced by high non-physiological level of L-galactone-1,4-lactone (L-GalL), the precursor of ascorbate (AsA), in plant mitochondria. The dysfunction induced by L-GalL was associated with the fault in the mitochondrial electron partition and reactive oxygen species (ROS) over-production. Using mitochondria from RNAi-plant lines harbouring silenced L-galactone-1,4-lactone dehydrogenase (L-GalLDH) activity, it was demonstrated that such dysfunction is dependent on this enzyme activity. The capacity of alternative respiration was strongly decreased by L-GalL, probably mediated by redox-inactivation of the alternative oxidase (AOX) enzyme. Although, alternative respiration was shown to be the key factor that helps support AsA synthesis in dysfunctional mitochondria. Experiments with respiratory inhibitors showed that ROS formation and mitochondrial dysfunction were more associated with the decline in the activities of COX (cytochrome oxidase) and particularly AOX than with the lower activities of respiratory complexes I and III. The application of high L-GalL concentrations induced proteomic changes that indicated alterations in proteins related to oxidative stress and energetic status. However, supra-optimal L-GalL concentration was not deleterious for plants. Instead, the L-GalLDH activity could be positive. Indeed, it was found that wild type plants performed better growth than L-GalLDH-RNAi plants in response to high non-physiological L-GalL concentrations.

Beneficial effects of Cyclosporine A in combination with Nortriptyline on germ cell-specific apoptosis, oxidative stress and epididymal sperm qualities following testicular ischemia/reperfusion in rats: a comparative study

Background

Testicular torsion is a pathological condition which needs emergency surgical intervention. However, after surgical reperfusion, oxidative stress factors cause to germ cell apoptosis. The study was planned to evaluate the efficacy of simultaneous use of Cyclosporine A (CsA) and Nortriptyline (Nort) to repair testicular damages in an experimental torsion/detorsion (T/D) rat model.

Methods

Male rats (n = 112) were allocated into 7 groups 16 each in; (Group 1); Control group, (Group 2); T/D group, (Group 3–4); CsA 1 and 5 mg/kg, (Group 5–6); Nort 2 and 10 mg/kg and (Group 7); concurrent group, CsA (1 mg/kg) + Nort (2 mg/kg). Right uni-lateral torsion was inducted by twisting testis 720 degrees in the clockwise direction for 1 h. For short-term and mid-term studies, lipid peroxidation, antioxidant enzyme activities, caspase-3 level, histopathological changes and germ cell apoptosis were evaluated. Moreover, in long-term investigation, semen analysis was performed.

Results

After T/D induction, testis abnormalities both functional and structural were appeared. Pre- and post-treatment with CsA and Nort, separately, reduced MDA and caspase-3 levels, normalized antioxidant levels, ameliorate tissue injury and improved sperm criteria.

Conclusion

The antioxidant and anti-apoptotic characteristics of CsA and Nort and their protective effects have been shown in our study. Concurrent administration of CsA and Nort in selected low-dose indicated a significant positive effect as compared to the individual drug interventions on the reversal of T/D induced oxidative stress in short-term, apoptosis, and histologic changes in mid-term, as well as semen criteria in the long-term appraisal.

Proteomic and Phosphoproteomic Analyses Reveal a Complex Network Regulating Pollen Abortion and Potential Candidate Proteins in TCMS Wheat

Thermosensitive sterile lines are natural materials for exploring the effects of anther development on male fertility. To study the possible molecular mechanisms regulating protein activity during the induction of male sterility, proteomic and phosphoproteomic analyses with tandem mass tags (TMTs) were used to study the binucleate anther of the thermosensitive sterile wheat line YS3038. A total of 9072 proteins, including 5019 phosphoproteins, were identified. Enrichment analyses of differentially abundant proteins (DAPs) and phosphoproteins (DAPPs) in metabolic pathways showed that both were mainly related to energy metabolism. Soluble sugar and ATP content were significantly decreased, free fatty acid content was significantly increased, and ROS was abnormally accumulated in male sterile YS3038-A. In addition, 233 kinase-substrate pairs involved in potential phosphorylation control networks were predicted to regulate fertility. Candidate proteins were identified, and a quantitative real-time polymerase chain reaction (qRT-PCR) analysis was used to validate the TMT results. TaPDCD5 is likely to be involved in fertility conversion of YS3038 by barley stripe mosaic virus-induced gene silencing (BSMV-VIGS). Our data provide new insights into the mechanism of TCMS, which has value for identifying potential candidate proteins associated with the formation or abortion of pollen and promotion of wheat heterosis utilization.

Oligodendrocyte death and myelin loss in the cuprizone model: an updated overview of the intrinsic and extrinsic causes of cuprizone demyelination

The dietary consumption of cuprizone – a copper chelator – has long been known to induce demyelination of specific brain structures and is widely used as model of multiple sclerosis. Despite the extensive use of cuprizone, the mechanism by which it induces demyelination are still unknown. With this review we provide an updated understanding of this model, by showcasing two distinct yet overlapping modes of action for cuprizone-induced demyelination; 1) damage originating from within the oligodendrocyte, caused by mitochondrial dysfunction or reduced myelin protein synthesis. We term this mode of action ‘intrinsic cell damage’. And 2) damage to the oligodendrocyte exerted by inflammatory molecules, brain resident cells, such as oligodendrocytes, astrocytes, and microglia or peripheral immune cells – neutrophils or T-cells. We term this mode of action ‘extrinsic cellular damage’. Lastly, we summarize recent developments in research on different forms of cell death induced by cuprizone, which could add valuable insights into the mechanisms of cuprizone toxicity. With this review we hope to provide a modern understanding of cuprizone-induced demyelination to understand the causes behind the demyelination in MS.

Knockdown or inhibition of arginine kinases enhances susceptibility of Tribolium castaneum to deltamethrin

Metabolism of insecticides is an energy-consuming process. As an important component of the intracellular energy buffering system, arginine kinase (AK) plays an important role in insect cellular energy homeostasis and environmental stress response, but the involvement of AKs in the response to chemical stressors (insecticides) remains largely unknown. In this study, using Tribolium castaneum as a model organism, we found that deltamethrin treatment significantly upregulated the expression of TcAK1 and TcAK2 and decreased the whole body ATP content. The knockdown of TcAK1 or TcAK2 significantly enhances the deltamethrin-induced ATP depletion and increase the susceptibility of T. castaneum to deltamethrin. In addition, pretreatment with two AK inhibitors, rutin and quercetin, significantly decreased the lifespan of beetles treated with deltamethrin. These results suggest that AKs might be involved in detoxification of insecticides by regulating cellular energy balance.

Glucose-6-phosphate dehydrogenase and abscisic acid mediate programmed cell death induced by aluminum toxicity in soybean root tips

Programmed cell death (PCD) induced by aluminum (Al) is considered an important reason of Al phytotoxicity. However, the underlying mechanism of how Al induces PCD remains largely unknown in plants. The roles of glucose-6-phosphate dehydrogenase (G6PDH) and abscisic acid (ABA) in regulating Al-induced PCD were investigated in soybean roots. Al treatment increased G6PDH activity, while inhibition of G6PDH activity alleviated PCD occurrence and reactive oxygen species (ROS) accumulation under Al stress. Overexpression of cytosolic G6PDH1 enhanced G6PDH activity, thus promoting ROS production and cell death under Al exposure. Inhibition of NADPH oxidase activity mitigated ROS generation and cell death under Al stress. Further investigation demonstrated that G6PDH positively regulated the activity of NADPH oxidase under Al treatment using pharmacological and transgenic approach. Furthermore, Al stress increased ABA production, while inhibition of ABA biosynthesis alleviated PCD occurrence and ROS accumulation under Al stress. Interestingly, ABA upregulated G6PDH1 expression and G6PDH activity under Al stress. These results suggest that G6PDH mediates Al-induced PCD occurrence through the activation of NADPH oxidase-dependent ROS production, and ABA acts upstream of G6PDH in this process. This study will provide novel clues for the improvement of Al phytotoxicity in acidic soils.

Defining key metabolic roles in osmotic adjustment and ROS homeostasis in the recretohalophyte Karelinia caspia under salt stress

The recretohalophyte Karelinia caspia is of forage and medical value and can remediate saline soils. We here assess the contribution of primary/secondary metabolism to osmotic adjustment and ROS homeostasis in Karelinia caspia under salt stress using multi-omic approaches. Computerized phenomic assessments, tests for cellular osmotic changes and lipid peroxidation indicated that salt treatment had no detectable physical effect on K. caspia. Metabolomic analysis indicated that amino acids, saccharides, organic acids, polyamine, phenolic acids, and vitamins accumulated significantly with salt treatment. Transcriptomic assessment identified differentially expressed genes closely linked to the changes in above primary/secondary metabolites under salt stress. In particular, shifts in carbohydrate metabolism (TCA cycle, starch and sucrose metabolism, glycolysis) as well as arginine and proline metabolism were observed to maintain a low osmotic potential. Chlorogenic acid/vitamin E biosynthesis was also enhanced, which would aid in ROS scavenging in the response of K. caspia to salt. Overall, our findings define key changes in primary/secondary metabolism that are coordinated to modulate the osmotic balance and ROS homeostasis to contribute to the salt tolerance of K. caspia.

Comparative Cytological and Transcriptome Analyses of Anther Development in Nsa Cytoplasmic Male Sterile (1258A) and Maintainer Lines in Brassica napus Produced by Distant Hybridization

1258A is a new line of B.napus with Nsa cytoplasmic male sterility (CMS) with potential applications in hybrid rapeseed breeding. Sterile cytoplasm was obtained from XinJiang Sinapis arvensis through distant hybridization and then backcrossed with 1258B for many generations. However, the characteristics and molecular mechanisms underlying pollen abortion in this sterile line are poorly understood. In this study, a cytological analysis revealed normal microsporogenesis and uninucleate pollen grain formation. Pollen abortion was due to non-programmed cell death in the tapetum and the inability of microspores to develop into mature pollen grains. Sucrose, soluble sugar, and adenosine triphosphate (ATP) contents during microspore development were lower than those of the maintainer line, along with an insufficient energy supply, reduced antioxidant enzyme activity, and substantial malondialdehyde (MDA) accumulation in the anthers. Transcriptome analysis revealed that genes involved in secondary metabolite biosynthesis, glutathione metabolism, phenylpropane biosynthesis, cyanoamino acid metabolism, starch and sucrose metabolism, and glycerolipid metabolism may contribute to pollen abortion. The down regulation of nine cytochrome P450 monooxygenases genes were closely associated with pollen abortion. These results suggest that pollen abortion in 1258A CMS stems from abnormalities in the chorioallantoic membranes, energy deficiencies, and dysfunctional antioxidant systems in the anthers. Our results provide insight into the molecular mechanism underlying pollen abortion in Nsa CMS and provide a theoretical basis for better heterosis utilization in B.napus.

Abnormal Oxidative Metabolism in the Cuprizone Mouse Model of Demyelination: an in vivo NIRS-MRI Study

Disruptions in oxidative metabolism may occur in multiple sclerosis and other demyelinating neurological diseases. The impact of demyelination on metabolic rate is also not understood. It is possible that mitochondrial damage may be associated with many such neurological disorders. To study oxidative metabolism with one model of demyelination, we implemented a novel multimodal imaging technique combining Near-Infrared Spectroscopy (NIRS) and MRI to cuprizone mouse model. The cuprizone model is used to study demyelination and may be associated with inhibition of mitochondrial function. Cuprizone mice showed reduced oxygen extraction fraction (-39.1%, p≤0.001), increased tissue oxygenation (6.4%, p≤0.001), and reduced cerebral metabolic rate of oxygen in cortical gray matter (-62.1%, p≤0.001). These changes resolved after the cessation of cuprizone exposure and partial remyelination. A decrease in hemoglobin concentration (-34.4%, p≤0.001), but no change in cerebral blood flow were also observed during demyelination. The oxidized state of the mitochondrial enzyme, Cytochrome C Oxidase (CCO) increased (46.3%, p≤0.001) while the reduced state decreased (-34.4%, p≤0.05) significantly in cuprizone mice. The total amount of CCO did not change significantly during cuprizone exposure. Total CCO did decline after recovery both in control (-23.1%, p≤0.01) and cuprizone (-28.8%, p≤0.001) groups which may relate to age. A reduction in the magnetization transfer ratio, indicating demyelination, was found in the cuprizone group in the cerebral cortex (-3.2%, p≤0.01) and corpus callosum (-5.5%, p≤0.001). In summary, we were able to detect evidence of altered CCO metabolism during cuprizone exposure, consistent with a mitochondrial defect. We observed increased oxygenation and reduced metabolic rate associated with reduced myelination in the gray and white matter. The novel multimodal imaging technique applied here shows promise for noninvasively assessing parameters associated with oxidative metabolism in both mouse models of neurological disease and for translation to study oxidative metabolism in the human brain.

A Frog Peptide Ameliorates Skin Photoaging Through Scavenging Reactive Oxygen Species

Although many bioactive peptides have been identified from the frog skins, their protective effects and the molecular mechanisms against skin photodamage are still poorly understood. In this study, a novel 20-residue peptide (antioxidin-NV, GWANTLKNVAGGLCKMTGAA) was characterized from the skin of plateau frog Nanorana ventripunctata. Antioxidin-NV obviously decreased skin erythema, thickness and wrinkle formation induced by Ultraviolet (UV) B exposure in hairless mice. In UVB-irradiated keratinocytes (HaCaT cells) and hairless mice, it effectively inhibited DNA damage through reducing p-Histone H2A.X (γH2AX) expression, alleviated cell apoptosis by decreasing the expression of apoptosis-specific protein (cleaved caspase 3), and reduced interleukin-6 (IL-6) production via blocking UVB-activated Toll-like receptor 4 (TLR4)/p38/JNK/NF-κB signaling. In UVB-irradiated human skin fibroblasts (HSF cells) and hairless mice, it effectively restored HSF cells survival rate, and rescued α-SMA accumulation and collagen (especially type I collagen) production by restoring transforming growth factor-β1 (TGF-β1)/Smad2 signaling. We found that antioxidin-NV directly and rapidly scavenged intracellular and mitochondrial ROS in HaCaT cells upon UVB irradiation, and quickly eliminated the artificial free radicals, 2, 2′-azinobis (3-ethylbenzothiazoline-6-sulfonic acid) (ABTS⁺). Taken together, antioxidin-NV directly and rapidly scavenged excessive ROS upon UVB irradiation, subsequently alleviated UVB-induced DNA damage, cell apoptosis, and inflammatory response, thus protecting against UVB-induced skin photoaging. These properties makes antioxidin-NV an excellent candidate for the development of novel anti-photoaging agent.

Peroxisomal support of mitochondrial respiratory efficiency promotes ER stress survival

Endoplasmic reticulum stress (ERS) occurs when cellular demand for protein folding exceeds the capacity of the organelle. Adaptation and cell survival in response to ERS requires a critical contribution by mitochondria and peroxisomes. During ERS responses, mitochondrial respiration increases to ameliorate reactive oxygen species (ROS) accumulation. We now show in yeast that peroxisome abundance also increases to promote an adaptive response. In pox1Δ cells, which are defective in peroxisomal β-oxidation of fatty acids, the respiratory response to ERS is impaired and ROS accrues. However, the respiratory response to ERS is rescued and ROS production is mitigated in pox1Δ cells overexpressing Mpc1, the mitochondrial pyruvate carrier that provides another source of acetyl CoA to fuel the tricarboxylic acid cycle and oxidative phosphorylation. Using proteomics, select mitochondrial proteins were identified that undergo upregulation upon ERS to remodel the respiratory machinery. The abundance of several peroxisome-based proteins was also increased, corroborating the role of peroxisomes in ERS adaptation. Finally, ERS stimulates assembly of respiratory complexes into higher-order supercomplexes, underlying increased electron transfer efficiency. Our results highlight peroxisomal and mitochondrial support for ERS adaptation to favor cell survival.

Melatonin Protects Tobacco Suspension Cells against Pb-Induced Mitochondrial Dysfunction

Recent studies have shown that melatonin is an important molecule in plant physiology. It seems that the most important is that melatonin effectively eliminates oxidative stress (direct and indirect antioxidant) and switches on different defence strategies (preventive and interventive actions) during environmental stresses. In the presented report, exogenous melatonin potential to protect Nicotiana tabacum L. line Bright Yellow 2 (BY-2) exposed to lead against death was examined. Analyses of cell proliferation and viability, the level of intracellular calcium, changes in mitochondrial membrane potential (ΔΨm) as well as possible translocation of cytochrome c from mitochondria to cytosol and subsequent caspase-like proteolytic activity were conducted. Our results indicate that pretreatment BY-2 with melatonin protected tobacco cells against mitochondrial dysfunction and caspase-like activation caused by lead. The findings suggest the possible role of this indoleamine in the molecular mechanism of mitochondria, safeguarding against potential collapse and cytochrome c release. Thus, it seems that applied melatonin acted as an effective factor, promoting survival and increasing plant tolerance to lead.

Oxidative and salt stresses alter the 26S proteasome holoenzyme and associated protein profiles in Arabidopsis thaliana

BACKGROUND

The 26S proteasome, canonically composed of multi-subunit 19S regulatory (RP) and 20S core (CP) particles, is crucial for cellular proteostasis. Proteasomes are re-modeled, activated, or re-localized and this regulation is critical for plants in response to environmental stresses. The proteasome holoenzyme assembly and dissociation are therefore highly dynamic in vivo. However, the stoichiometric changes of the plant proteasomes and how proteasome associated chaperones vary under common abiotic stresses have not been systematically studied.

RESULTS

Here, we studied the impact of abiotic stresses on proteasome structure, activity, and interacting partners in Arabidopsis thaliana. We analyzed available RNA expression data and observed that expressions of proteasome coding genes varied substantially under stresses; however, the protein levels of a few key subunits did not change significantly within 24 h. Instead, a switch in the predominant proteasome complex, from 26S to 20S, occurs under oxidative or salt stress. Oxidative stress also reduced the cellular ATP content and the association of HSP70-family proteins to the 20S proteasome, but enhanced the activity of cellular free form CP. Salt stress, on the other hand, did not affect cellular ATP level, but caused subtle changes in proteasome subunit composition and impacted bindings of assembly chaperones. Analyses of an array of T-DNA insertional mutant lines highlighted important roles for several putative assembly chaperones in seedling establishment and stress sensitivity. We also observed that knockout of PBAC1, one of the α-ring assembly chaperones, resulted in reduced germination and tearing of the seed coat following sterilization.

CONCLUSIONS

Our study revealed an evolutionarily conserved mechanism of proteasome regulation during oxidative stress, involving dynamic regulation of the holoenzyme formation and associated regulatory proteins, and we also identified a novel role of the PBAC1 proteasome assembly chaperone in seed coat development.

The potential of prodigiosin for control of Prorocentrum donghaiense blooms: Algicidal properties and acute toxicity to other marine organisms at various trophic levels

Prorocentrum donghaiense, a marine dinoflagellate, causes harmful algal blooms (HABs) characterised by the highest outbreak frequency and most extensive coverage among similar species in the East China Sea. Highly efficient and ecofriendly biocontrol strategies should be developed for HAB control. Prodigiosin is an efficient biological algicide that demonstrated strong algicidal activity towards P. donghaiense. However, the mechanism of its toxicity to P. donghaiense is unknown. These factors were investigated to evaluate potential use of prodigiosin for control of P. donghaiense blooms. Photosynthetic electron transport rate, maximum quantum yield and respiration rate of P. donghaiense decreased significantly upon exposure to prodigiosin, indicating that prodigiosin rapidly exerted adverse effects on the chloroplasts and mitochondria. Furthermore, a significant increase in dichlorofluorescein fluorescence intensity indicated an overproduction of reactive oxygen species (ROS). The antioxidant system of P. donghaiense scavenged ROS; however, an increase in malondialdehyde concentrations indicated that excessive ROS were still able to initiate lipid peroxidation. Thus, ROS production resulted in the formation of lipids with a reduced degree of unsaturation. Lipid peroxidation decreased lipid fluidity and rigidified the membrane system, causing serious functional destruction of the membrane. Flow cytometry analysis indicated that prodigiosin arrested the cell cycle of P. donghaiense. However, surviving algal cells were able to repair the damaged functions and resume the cell cycle after prodigiosin was removed by photodegradation. Otherwise, P. donghaiense cells lost their membrane integrity and died. To begin an evaluation of ecological safety of prodigiosin, we tested four marine organisms at various trophic levels. The results of these tests indicated that Chlorella vulgaris, Photobacterium phosphoreum, Artemia salina and Lateolabrax japonicus were less sensitive to prodigiosin than P. donghaiense. Toxicity to all five organisms declined after prodigiosin was exposed to sunlight for 6 h. Considering the toxic doses of prodigiosin to various organisms and its photodegradation characteristics, we suggest that prodigiosin has potential in controlling P. donghaiense blooms but should be applied at night, in small doses, with multiple applications.

Rooibos Flavonoids, Aspalathin, Isoorientin, and Orientin Ameliorate Antimycin A-Induced Mitochondrial Dysfunction by Improving Mitochondrial Bioenergetics in Cultured Skeletal Muscle Cells

The current study investigated the physiological effects of flavonoids found in daily consumed rooibos tea, aspalathin, isoorientin, and orientin on improving processes involved in mitochondrial function in C2C12 myotubes. To achieve this, C2C12 myotubes were exposed to a mitochondrial channel blocker, antimycin A (6.25 µM), for 12 h to induce mitochondrial dysfunction. Thereafter, cells were treated with aspalathin, isoorientin, and orientin (10 µM) for 4 h, while metformin (1 µM) and insulin (1 µM) were used as comparators. Relevant bioassays and real-time PCR were conducted to assess the impact of treatment compounds on some markers of mitochondrial function. Our results showed that antimycin A induced alterations in the mitochondrial respiration process and mRNA levels of genes involved in energy production. In fact, aspalathin, isoorientin, and orientin reversed such effects leading to the reduced production of intracellular reactive oxygen species. These flavonoids further enhanced the expression of genes involved in mitochondrial function, such as Ucp 2, Complex 1/3, Sirt 1, Nrf 1, and Tfam. Overall, the current study showed that dietary flavonoids, aspalathin, isoorientin, and orientin, have the potential to be as effective as established pharmacological drugs such as metformin and insulin in protecting against mitochondrial dysfunction in a preclinical setting; however, such information should be confirmed in well-established in vivo disease models.

Identification of Biochemical and Molecular Markers of Early Aging in Childhood Cancer Survivors

Simple Summary

Childhood cancer survivors (CCS) display a higher risk of developing second malignant tumors and chronic diseases compared with aged-matched controls because of chemo/radiotherapy. This early frailty seems associated with accelerated cell aging, a process correlated with altered mitochondrial energy production. Therefore, this work aims to shed light on the mechanisms involved in chemo/radiotherapy-induced early aging, morbidities, and the risk of developing second tumors in CCS through a biochemical and molecular approach. The identification of crucial mechanisms involved in the CCS chemo/radiotherapy-related pathological conditions will allow identifying therapeutic targets to develop appropriate risk-based care and interventions, minimize morbidities, and maximize the quality of life in the cancer survivor population.

Abstract

Survival rates of childhood cancer patients have improved over the past four decades, although cancer treatments increase the risk of developing chronic diseases typical of aging. Thus, we aimed to identify molecular/metabolic cellular alterations responsible for early aging in childhood cancer survivors (CCS). Biochemical, proteomic, and molecular biology analyses were conducted on mononuclear cells (MNCs) isolated from peripheral blood of 196 CCS, the results being compared with those obtained on MNCs of 154 healthy subjects. CCS-MNCs showed inefficient oxidative phosphorylation associated with low energy status, and increased lipid peroxidation and lactate fermentation compared with age-matched normal controls. According to a mathematical model based on biochemical parameters, CCS-MNCs showed significantly higher metabolic ages than their real ages. The dysfunctional metabolism of CCS-MNCs is associated with lower expression levels of genes and proteins involved in mitochondrial biogenesis and metabolism regulation, such as CLUH, PGC1-alpha, and SIRT6 in CCS, not observed in the age-matched healthy or elderly subjects. In conclusion, our study identified some biochemical and molecular alterations possibly contributing to the pathophysiology of aging and metabolic deficiencies in CCS. These results identify new targets for pharmacological interventions to restore mitochondrial function, slowing down the aging-associated pathologies in CCS.

Mitochondrial phosphate transporter and methyltransferase genes contribute to Fusarium head blight Type II disease resistance and grain development in wheat

Fusarium head blight (FHB) is an economically important disease of wheat that results in yield loss and grain contaminated with fungal mycotoxins that are harmful to human and animal health. Herein we characterised two wheat genes involved in the FHB response in wheat: a wheat mitochondrial phosphate transporter (TaMPT) and a methyltransferase (TaSAM). Wheat has three sub-genomes (A, B, and D) and gene expression studies demonstrated that TaMPT and TaSAM homoeologs were differentially expressed in response to FHB infection and the mycotoxigenic Fusarium virulence factor deoxynivalenol (DON) in FHB resistant wheat cv. CM82036 and susceptible cv. Remus. Virus-induced gene silencing (VIGS) of either TaMPT or TaSAM enhanced the susceptibility of cv. CM82036 to FHB disease, reducing disease spread (Type II disease resistance). VIGS of TaMPT and TaSAM significantly reduced grain number and grain weight. This indicates TaSAM and TaMPT genes also contribute to grain development in wheat and adds to the increasing body of evidence linking FHB resistance genes to grain development. Hence, Fusarium responsive genes TaSAM and TaMPT warrant further study to determine their potential to enhance both disease resistance and grain development in wheat.

Titanium dioxide nanoparticles enhance thrombosis through triggering the phosphatidylserine exposure and procoagulant activation of red blood cells

Background

Expanding biomedical application of anatase titanium dioxide (TiO₂) nanoparticles (NPs) is raising the public concern on its potential health hazards. Here, we demonstrated that TiO₂ NPs can increase phosphatidylserine (PS) exposure and procoagulant activity of red blood cells (RBCs), which may contribute to thrombosis.

Results

We conducted in vitro studies using RBCs freshly isolated from healthy male volunteers. TiO₂ NPs exposure (≦ 25 μg/mL) induced PS exposure and microvesicles (MV) generation accompanied by morphological changes of RBCs. While ROS generation was not observed following the exposure to TiO₂ NPs, intracellular calcium increased and caspase-3 was activated, which up-regulated scramblase activity, leading to PS exposure. RBCs exposed to TiO₂ NPs could increase procoagulant activity as measured by accelerated thrombin generation, and enhancement of RBC-endothelial cells adhesion and RBC-RBC aggregation. Confirming the procoagulant activation of RBC in vitro, exposure to TiO₂ NPs (2 mg/kg intravenously injection) in rats increased thrombus formation in the venous thrombosis model.

Conclusion

Collectively, these results suggest that anatase TiO₂ NPs may harbor prothrombotic risks by promoting the procoagulant activity of RBCs, which needs attention for its biomedical application.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12989-021-00422-1.

Mitochondrial Bioenergetic, Photobiomodulation and Trigeminal Branches Nerve Damage, What's the Connection? A Review

BACKGROUND

Injury of the trigeminal nerve in oral and maxillofacial surgery can occur. Schwann cell mitochondria are regulators in the development, maintenance and regeneration of peripheral nerve axons. Evidence shows that after the nerve injury, mitochondrial bioenergetic dysfunction occurs and is associated with pain, neuropathy and nerve regeneration deficit. A challenge for research is to individuate new therapies able to normalise mitochondrial and energetic metabolism to aid nerve recovery after damage. Photobiomodulation therapy can be an interesting candidate, because it is a technique involving cell manipulation through the photonic energy of a non-ionising light source (visible and NIR light), which produces a nonthermal therapeutic effect on the stressed tissue.

METHODS

The review was based on the following questions: (1) Can photo-biomodulation by red and NIR light affect mitochondrial bioenergetics? (2) Can photobiomodulation support damage to the trigeminal nerve branches? (preclinical and clinical studies), and, if yes, (3) What is the best photobiomodulatory therapy for the recovery of the trigeminal nerve branches? The papers were searched using the PubMed, Scopus and Cochrane databases. This review followed the ARRIVE-2.0, PRISMA and Cochrane RoB-2 guidelines.

RESULTS AND CONCLUSIONS

The reliability of photobiomodulatory event strongly bases on biological and physical-chemical evidence. Its principal player is the mitochondrion, whether its cytochromes are directly involved as a photoacceptor or indirectly through a vibrational and energetic variation of bound water: water as the photoacceptor. The 808-nm and 100 J/cm2 (0.07 W; 2.5 W/cm2; pulsed 50 Hz; 27 J per point; 80 s) on rats and 800-nm and 0.2 W/cm2 (0.2 W; 12 J/cm2; 12 J per point; 60 s, CW) on humans resulted as trustworthy therapies, which could be supported by extensive studies.

Regulation of metastasis suppressor NME1 by a key metabolic cofactor coenzyme A

The metastasis suppressor protein NME1 is an evolutionarily conserved and multifunctional enzyme that plays an important role in suppressing the invasion and metastasis of tumour cells. The nucleoside diphosphate kinase (NDPK) activity of NME1 is well recognized in balancing the intracellular pools of nucleotide diphosphates and triphosphates to regulate cytoskeletal rearrangement and cell motility, endocytosis, intracellular trafficking, and metastasis. In addition, NME1 was found to function as a protein-histidine kinase, 3′-5′ exonuclease and geranyl/farnesyl pyrophosphate kinase. These diverse cellular functions are regulated at the level of expression, post-translational modifications, and regulatory interactions. The NDPK activity of NME1 has been shown to be inhibited in vitro and in vivo under oxidative stress, and the inhibitory effect mediated via redox-sensitive cysteine residues. In this study, affinity purification followed by mass spectrometric analysis revealed NME1 to be a major coenzyme A (CoA) binding protein in cultured cells and rat tissues. NME1 is also found covalently modified by CoA (CoAlation) at Cys109 in the CoAlome analysis of HEK293/Pank1β cells treated with the disulfide-stress inducer, diamide. Further analysis showed that recombinant NME1 is efficiently CoAlated in vitro and in cellular response to oxidising agents and metabolic stress. In vitro CoAlation of recombinant wild type NME1, but not the C109A mutant, results in the inhibition of its NDPK activity. Moreover, CoA also functions as a competitive inhibitor of the NME1 NDPK activity by binding non-covalently to the nucleotide binding site. Taken together, our data reveal metastasis suppressor protein NME1 as a novel binding partner of the key metabolic regulator CoA, which inhibits its nucleoside diphosphate kinase activity via non-covalent and covalent interactions.

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NME1 is a major CoA-binding protein.

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CoA can bind NME1 through covalent and non-covalent interactions.

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NME1 CoAlation is induced by oxidative and metabolic stress in mammalian cells.

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CoA inhibits the NDPK activity of NME1 in vitro.

The Cys Sense: Thiol Redox Switches Mediate Life Cycles of Cellular Proteins

Protein homeostasis is an essential component of proper cellular function; however, sustaining protein health is a challenging task, especially during the aerobic lifestyle. Natural cellular oxidants may be involved in cell signaling and antibacterial defense; however, imbalanced levels can lead to protein misfolding, cell damage, and death. This merges together the processes of protein homeostasis and redox regulation. At the heart of this process are redox-regulated proteins or thiol-based switches, which carefully mediate various steps of protein homeostasis across folding, localization, quality control, and degradation pathways. In this review, we discuss the "redox code" of the proteostasis network, which shapes protein health during cell growth and aging. We describe the sources and types of thiol modifications and elaborate on diverse strategies of evolving antioxidant proteins in proteostasis networks during oxidative stress conditions. We also highlight the involvement of cysteines in protein degradation across varying levels, showcasing the importance of cysteine thiols in proteostasis at large. The individual examples and mechanisms raised open the door for extensive future research exploring the interplay between the redox and protein homeostasis systems. Understanding this interplay will enable us to re-write the redox code of cells and use it for biotechnological and therapeutic purposes.

Glycine alleviates fluoride-induced oxidative stress, apoptosis and senescence in a porcine testicular Sertoli cell line

Glycine is a well-known free radical scavenger in the cellular antioxidant system that prevents oxidative damage and apoptosis. Excessive fluoride exposure is associated with multiple types of cellular damage in humans and animals. The objective of the present study was to investigate the protective effects of glycine on sodium fluoride (NaF) exposure and the possible underlying mechanisms in a porcine testicular Sertoli cell line model. Cellular viability and proliferation were examined following NaF exposure and glycine supplementation, and glycine dramatically ameliorated the decreases in NaF-induced porcine testicular Sertoli cell viability and proliferation. Further investigations revealed that glycine decreased NaF-induced intracellular reactive oxygen species production, DNA fragment accumulation and the apoptosis incidence in the porcine testicular Sertoli cell line; in addition, glycine improved mitochondrial function and ATP production. Notably, results of the SPiDER-β-Gal analysis suggested that glycine alleviated NaF-induced cellular senescence and downregulated P53, P21, HMGA2 and P16INK4a gene expression in the porcine testicular Sertoli cell line. Collectively, the beneficial effects of glycine alleviate NaF-induced oxidative stress, apoptosis and senescence, and together with our previous findings, support the hypothesis that glycine plays an important role in protecting against NaF exposure-induced impairments in the porcine testicular Sertoli cell line.

Combined Transcriptome Analysis Reveals the Ovule Abortion Regulatory Mechanisms in the Female Sterile Line of Pinus tabuliformis Carr

Ovule abortion is a common phenomenon in plants that has an impact on seed production. Previous studies of ovule and female gametophyte (FG) development have mainly focused on angiosperms, especially in Arabidopsis thaliana. However, because it is difficult to acquire information about ovule development in gymnosperms, this remains unclear. Here, we investigated the transcriptomic data of natural ovule abortion mutants (female sterile line, STE) and the wild type (female fertile line, FER) of Pinus tabuliformis Carr. to evaluate the mechanism of ovule abortion during the process of free nuclear mitosis (FNM). Using single-molecule real-time (SMRT) sequencing and next-generation sequencing (NGS), 18 cDNA libraries via Illumina and two normalized libraries via PacBio, with a total of almost 400,000 reads, were obtained. Our analysis showed that the numbers of isoforms and alternative splicing (AS) patterns were significantly variable between FER and STE. The functional annotation results demonstrate that genes involved in the auxin response, energy metabolism, signal transduction, cell division, and stress response were differentially expressed in different lines. In particular, AUX/IAA, ARF2, SUS, and CYCB had significantly lower expression in STE, showing that auxin might be insufficient in STE, thus hindering nuclear division and influencing metabolism. Apoptosis in STE might also have affected the expression levels of these genes. To confirm the transcriptomic analysis results, nine pairs were confirmed by quantitative real-time PCR. Taken together, these results provide new insights into ovule abortion in gymnosperms and further reveal the regulatory mechanisms of ovule development.

Mitochondrial Permeability Transition: A Pore Intertwines Brain Aging and Alzheimer's Disease

Advanced age is the greatest risk factor for aging-related brain disorders including Alzheimer's disease (AD). However, the detailed mechanisms that mechanistically link aging and AD remain elusive. In recent years, a mitochondrial hypothesis of brain aging and AD has been accentuated. Mitochondrial permeability transition pore (mPTP) is a mitochondrial response to intramitochondrial and intracellular stresses. mPTP overactivation has been implicated in mitochondrial dysfunction in aging and AD brains. This review summarizes the up-to-date progress in the study of mPTP in aging and AD and attempts to establish a link between brain aging and AD from a perspective of mPTP-mediated mitochondrial dysfunction.

Photobiomodulation and Oxidative Stress: 980 nm Diode Laser Light Regulates Mitochondrial Activity and Reactive Oxygen Species Production

Photobiomodulation with 808 nm laser light electively stimulates Complexes III and IV of the mitochondrial respiratory chain, while Complexes I and II are not affected. At the wavelength of 1064 nm, Complexes I, III, and IV are excited, while Complex II and some mitochondrial matrix enzymes seem to be not receptive to photons at that wavelength. Complex IV was also activated by 633 nm. The mechanism of action of wavelengths in the range 900–1000 nm on mitochondria is less understood or not described. Oxidative stress from reactive oxygen species (ROS) generated by mitochondrial activity is an inescapable consequence of aerobic metabolism. The antioxidant enzyme system for ROS scavenging can keep them under control. However, alterations in mitochondrial activity can cause an increment of ROS production. ROS and ATP can play a role in cell death, cell proliferation, and cell cycle arrest. In our work, bovine liver isolated mitochondria were irradiated for 60 sec, in continuous wave mode with 980 nm and powers from 0.1 to 1.4 W (0.1 W increment at every step) to generate energies from 6 to 84 J, fluences from 7.7 to 107.7 J/cm², power densities from 0.13 to 1.79 W/cm², and spot size 0.78 cm². The control was equal to 0 W. The activity of the mitochondria's complexes, Krebs cycle enzymes, ATP production, oxygen consumption, generation of ROS, and oxidative stress were detected. Lower powers (0.1–0.2 W) showed an inhibitory effect; those that were intermediate (0.3–0.7 W) did not display an effect, and the higher powers (0.8–1.1 W) induced an increment of ATP synthesis. Increasing the power (1.2–1.4 W) recovered the ATP production to the control level. The interaction occurred on Complexes III and IV, as well as ATP production and oxygen consumption. Results showed that 0.1 W uncoupled the respiratory chain and induced higher oxidative stress and drastic inhibition of ATP production. Conversely, 0.8 W kept mitochondria coupled and induced an increase of ATP production by increments of Complex III and IV activities. An augmentation of oxidative stress was also observed, probably as a consequence of the increased oxygen consumption and mitochondrial isolation experimental conditions. No effect was observed using 0.5 W, and no effect was observed on the enzymes of the Krebs cycle.

Integrative role of plant mitochondria facing oxidative stress: The case of ozone

Ozone is a secondary air pollutant, which causes oxidative stress in plants by producing reactive oxygen species (ROS) starting by an external attack of leaf apoplast. ROS have a dual role, acting as signaling molecules, regulating different physiological processes and response to stress, but also inducing oxidative damage. The production of ROS in plant cells is compartmented and regulated by scavengers and specific enzyme pathways. Chronic doses of ozone are known to trigger an important increase of the respiratory process while decreasing photosynthesis. Mitochondria, which normally operate with usual levels of intracellular ROS, would have to play a prominent role to cope with an enhanced ozone-derived ROS production. It is thus needed to compile the available literature on the effects of ozone on mitochondria to precise their strategy facing oxidative stress. An overview of the mitochondrial fate in three steps is proposed, i) starting with the initial responses of the mitochondria for alleviating the overproduction of ROS by the enhancement of existing antioxidant metabolism and adjustments of the electron transport chain, ii) followed by the setting up of detoxifying processes through exchanges between mitochondria and the cell, and iii) ending by an accelerated senescence initiated by mitochondrial membrane permeability and leading to programmed cell death.

Role of Apoptotic Cell Clearance in Pneumonia and Inflammatory Lung Disease

Pneumonia and inflammatory diseases of the pulmonary system such as chronic obstructive pulmonary disease and asthma continue to cause significant morbidity and mortality globally. While the etiology of these diseases is highly different, they share a number of similarities in the underlying inflammatory processes driving disease pathology. Multiple recent studies have identified failures in efferocytosis-the phagocytic clearance of apoptotic cells-as a common driver of inflammation and tissue destruction in these diseases. Effective efferocytosis has been shown to be important for resolving inflammatory diseases of the lung and the subsequent restoration of normal lung function, while many pneumonia-causing pathogens manipulate the efferocytic system to enhance their growth and avoid immunity. Moreover, some treatments used to manage these patients, such as inhaled corticosteroids for chronic obstructive pulmonary disease and the prevalent use of statins for cardiovascular disease, have been found to beneficially alter efferocytic activity in these patients. In this review, we provide an overview of the efferocytic process and its role in the pathophysiology and resolution of pneumonia and other inflammatory diseases of the lungs, and discuss the utility of existing and emerging therapies for modulating efferocytosis as potential treatments for these diseases.