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

Experimental evolution: its principles and applications in developing stress-tolerant yeasts

Stress tolerance and resistance in industrial yeast strains are important attributes for cost-effective bioprocessing. The source of stress-tolerant yeasts ranges from extremophilic environments to laboratory engineered strains. However, industrial stress-tolerant yeasts are very rare in nature as the natural environment forces them to evolve traits that optimize survival and reproduction and not the ability to withstand harsh habitat-irrelevant industrial conditions. Experimental evolution is a frequent method used to uncover the mechanisms of evolution and microbial adaption towards environmental stresses. It optimizes biological systems by means of adaptation to environmental stresses and thus has immense power of development of robust stress-tolerant yeasts. This mini-review briefly outlines the basics and implications of evolution experiments and their applications to industrial biotechnology. This work is meant to serve as an introduction to those new to the field of experimental evolution, and as a guide to biologists working in the field of yeast stress response. Future perspectives of experimental evolution for potential biotechnological applications have also been elucidated.

Analysis of Redox Relationships in the Plant Cell Cycle: Determination of Ascorbate, Glutathione, and Poly(ADPribose)polymerase (PARP) in Plant Cell Cultures

Reactive oxygen species (ROS) and low molecular weight antioxidants, such as glutathione and ascorbate, are powerful signalling molecules that participate in the control of plant growth and development, and modulate progression through the mitotic cell cycle. Enhanced ROS accumulation or low levels of ascorbate or glutathione cause the cell cycle to arrest and halt progression especially through the G1 checkpoint. Plant cell suspension cultures have proved to be particularly useful tools for the study of cell cycle regulation. Here we provide effective and accurate methods for the measurement of changes in the cellular ascorbate and glutathione pools and the activities of related enzymes such poly(ADP-ribose)polymerase (PARP) during mitosis and cell expansion, particularly in cell suspension cultures. These methods can be used in studies seeking to improve current understanding of the roles of redox controls on cell division and cell expansion.

Effects of 5-Aminolevulinic Acid on Gene Expression, Immunity, and ATP Levels in Pacific White Shrimp, Litopenaeus vannamei

With the emergence of several infectious diseases in shrimp aquaculture, there is a growing interest in the use of feed additives to enhance shrimp immunity. Recently, the use of 5-aminolevulinic acid (5-ALA), a non-protein amino acid that plays a rate-limiting role in heme biosynthesis, has received attention for its positive effect on immunity in livestock animals. To evaluate the effect of 5-ALA in the Pacific white shrimp, Litopenaeus vannamei, we conducted microarray analysis, a Vibrio parahaemolyticus immersion challenge test, an ATP level assay, and gene expression analysis of some hemoproteins and genes associated with heme synthesis and degradation. Out of 15,745 L. vannamei putative genes on the microarray, 101 genes were differentially expressed by more than fourfold (p < 0.05) between 5-ALA-supplemented and control shrimp hepatopancreas. 5-ALA upregulated 99 of the 101 genes, 41 of which were immune- and defense-related genes based on sequence homology. Compared to the control, the 5-ALA-supplemented group had a higher survival rate in the challenge test, higher transcript levels of porphobilinogen synthase, ferrochelatase, catalase, nuclear receptor E75, and heme oxygenase-1 and higher levels of ATP. These findings suggest that dietary 5-ALA enhanced the immune response of L. vannamei to V. parahaemolyticus, upregulated immune- and defense-related genes, and enhanced aerobic energy metabolism, respectively. Further studies are needed to elucidate the extent of 5-ALA use in shrimp culture.

Generation of brilliant green fluorescent petunia plants by using a new and potent fluorescent protein transgene

The application of fluorescent proteins in ornamental plants has lagged behind despite the recent development of powerful genetic tools. Although we previously generated transgenic torenia plants expressing green fluorescent protein from marine plankton (CpYGFP), in which bright fluorescence was easily visible at the whole plant level, the maximum excitation of this protein within the visible light spectrum required the use of a coloured emission filter to eliminate exciting light. Here, to overcome this limitation, we generated transgenic petunia plants expressing eYGFPuv, a CpYGFP derivative exhibiting bright fluorescence under invisible ultraviolet (UV) light excitation, with a novel combination of transcriptional terminator plus translational enhancer. As expected, all transgenic plants exhibited brilliant green fluorescence easily visible to the naked eye without an emission filter. In addition, fluorescence expressed in transgenic petunia flowers was stable during long-term vegetative propagation. Finally, we visually and quantitatively confirmed that transgenic petunia flowers resist to long-term exposure of UV without any damages such as fluorescence decay and withering. Thus, our whole-plant fluorescence imaging tool, that does not require high sensitive imaging equipment or special imaging conditions for observation, might be useful not only for basic plant research but also for ornamental purposes as a novel flower property.

Unconventional oil and gas chemicals and wastewater-impacted water samples promote adipogenesis via PPARγ-dependent and independent mechanisms in 3T3-L1 cells

Unconventional oil and natural gas (UOG) operations have contributed to a surge in domestic oil and natural gas production in the United States, combining horizontal drilling with hydraulic fracturing to unlock previously inaccessible fossil fuel deposits. >1000 organic chemicals are used in the production process, and wastewater is produced following injection and for the life of the producing well. This wastewater is typically disposed of via injecting into disposal wells for long-term storage, treatment and discharge from wastewater treatment plants, and/or storage in open evaporation pits; however, wastewater spill rates are reported at 2-20% of active well sites across regions, increasing concerns about the environmental impacts of these wastewaters. This study assessed adipogenic activity (both triglyceride accumulation and pre-adipocyte proliferation) for a mixture of 23 commonly used UOG chemicals and a small subset of UOG wastewater-impacted surface water extracts from Colorado and West Virginia, using 3T3-L1 cells and a peroxisome proliferator activated receptor gamma (PPARγ) reporter assay. We report potent and efficacious adipogenic activity induced by both a laboratory-created UOG chemical mixture and UOG-impacted water samples at concentrations below environmental levels. We further report activation of PPARγ at similar concentrations for some samples, suggesting a causative molecular pathway for the observed effects, but not for other adipogenic samples, implicating PPARγ-dependent and independent effects from UOG associated chemicals. Taken together, these results suggest that UOG wastewater has the potential to impact metabolic health at environmentally relevant concentrations.

The release of cytochrome c and the regulation of the programmed cell death progress in the endosperm of winter wheat (Triticum aestivum L.) under waterlogging

It has been shown in mammalian systems that the mitochondria can play a key role in the regulation of apoptosis by releasing intermembrane proteins (such as cytochrome c) into the cytosol. Cytochrome c released from the mitochondria to the cytoplasm activates proteolytic enzyme cascades, leading to specific nuclear DNA degradation and cell death. This pathway is considered to be one of the important regulatory mechanisms of apoptosis. Previous studies have shown that endosperm cell development in wheat undergoes specialized programmed cell death (PCD) and that waterlogging stress accelerates the PCD process; however, little is known regarding the associated molecular mechanism. In this study, changes in mitochondrial structure, the release of cytochrome c, and gene expression were studied in the endosperm cells of the wheat (Triticum aestivum L.) cultivar "huamai 8" during PCD under different waterlogging durations. The results showed that waterlogging aggravated the degradation of mitochondrial structure, increased the mitochondrial permeability transition (MPT), and decreased mitochondrial transmembrane potential (ΔΨm), resulting in the advancement of the endosperm PCD process. In situ localization and western blotting of cytochrome c indicated that with the development of the endosperm cell, cytochrome c was gradually released from the mitochondria to the cytoplasm, and waterlogging stress led to an advancement and increase in the release of cytochrome c. In addition, waterlogging stress resulted in the increased expression of the voltage-dependent anion channel (VDAC) and adenine nucleotide translocator (ANT), suggesting that the mitochondrial permeability transition pore (MPTP) may be involved in endosperm PCD under waterlogging stress. The MPTP inhibitor cyclosporine A effectively suppressed cell death and cytochrome c release during wheat endosperm PCD. Our results indicate that the mitochondria play important roles in the PCD of endosperm cells and that the increase in mitochondrial damage and corresponding release of cytochrome c may be one of the major causes of endosperm PCD advancement under waterlogging.

The Fight Against Panax notoginseng Root-Rot Disease Using Zingiberaceae Essential Oils as Potential Weapons

The root of Panax notoginseng (P. notoginseng) is one of the most highly valuable medicinal herbs in China owing to its pronounced hemostatic and restorative properties. Despite this important fact, growing P. notoginseng is seriously limited by root-rot diseases. In studies aimed at developing a solution to this problem, environment-friendly essential oils (EOs) of five medicinal plants of the family Zingiberaceae were tested for their inhibitory effects on the growth of three main soil pathogens associated with the root-rot diseases of P. notoginseng. The results showed that the EOs of Alpinia katsumadai Hayata and Zingiber officinale Roscoe promote significant reductions in the mycelium growth of the pathogen in vitro at a concentration of 50 mg mL-1, which is much higher than that needed (5 mg mL-1) to reduce growth by the positive control, flutriafol. Furthermore, the chemical components of the two EOs were determined by using GC-MS analysis. Eucalyptol was found to account for more than 30% of the oils of the two plants, with the second major components being geranyl acetate and α-terpineol. These substances display different degrees of fungistasis in vitro. To further determine the effects of the EO of Zingiber officinale (Z. officinale) in vivo, soilless cultivation of P. notoginseng with pathogen inoculation was conducted in a greenhouse. Addition of the petroleum ether extract (approximately equal to EO) of Z. officinale to the culture matrix causes a large decrease in both the occurrence and severity of the P. notoginseng root-rot disease. The decreasing trend of net photosynthetic rate (Pn), stomatal conductance (gs), intercellular CO2 concentration (Ci), and transpiration rate (Tr) were all alleviated. In addition, the activities of catalase (CAT), peroxidase (POD), and the malondialdehyde (MDA) content were also largely reduced after pathogen infection, with the root activity being higher than that of the control. Taken together, the findings reveal that the EOs from plants might serve as promising sources of eco-friendly natural pesticides with less chemical resistance.

Data-driven modeling of mitochondrial dysfunction in Alzheimer's disease

Intracellular accumulation of oligomeric forms of β amyloid (Aβ) are now believed to play a key role in the earliest phase of Alzheimer's disease (AD) as their rise correlates well with the early symptoms of the disease. Extensive evidence points to impaired neuronal Ca²⁺ homeostasis as a direct consequence of the intracellular Aβ oligomers. However, little is known about the downstream effects of the resulting Ca²⁺ rise on the many intracellular Ca²⁺-dependent pathways. Here we use multiscale modeling in conjunction with patch-clamp electrophysiology of single inositol 1,4,5-trisphosphate (IP₃) receptor (IP₃R) and fluorescence imaging of whole-cell Ca²⁺ response, induced by exogenously applied intracellular Aβ₄₂ oligomers to show that Aβ₄₂ inflicts cytotoxicity by impairing mitochondrial function. Driven by patch-clamp experiments, we first model the kinetics of IP₃R, which is then extended to build a model for the whole-cell Ca²⁺ signals. The whole-cell model is then fitted to fluorescence signals to quantify the overall Ca²⁺ release from the endoplasmic reticulum by intracellular Aβ₄₂ oligomers through G-protein-mediated stimulation of IP₃ production. The estimated IP₃ concentration as a function of intracellular Aβ₄₂ content together with the whole-cell model allows us to show that Aβ₄₂ oligomers impair mitochondrial function through pathological Ca²⁺ uptake and the resulting reduced mitochondrial inner membrane potential, leading to an overall lower ATP and increased production of reactive oxygen species and H₂O₂. We further show that mitochondrial function can be restored by the addition of Ca²⁺ buffer EGTA, in accordance with the observed abrogation of Aβ₄₂ cytotoxicity by EGTA in our live cells experiments.

Syzygium Aromaticum Alleviates Cerium Chloride-Induced Neurotoxic Effect In The Adult Mice

Previous studies have brought to light the toxic effect of cerium chloride (CeCl₃) but very little is known about the oxidative brain injury caused by this metal. Medical plants have a well-recognized role in the management of damage caused by pollutants such as CeCl₃. Syzygium aromaticum, a potent natural source of bioactive compounds and rich in secondary metabolites, has a broad range of biological functions. The aim of this study is to investigate the capacity of Syzygium aromaticum ethanol extract (ESA) to improve the adverse effects of CeCl₃ in the brain tissue. Adult mice were exposed to CeCl₃ (20 mg/kg body weight [BW]), with or without ESA, for 60 days. We investigate mice's behavior, damages of cholinergic system and oxidative stress parameters in mice brain. In the present study, in vitro test confirmed that ESA has antioxidant capacity attributed to the presence of flavonoids, polyphenols, and tannins contents. In vivo study showed that CeCl₃ caused brain injuries manifested in memory impairment, increase in acetylcholinesterase activity, oxidative stress biomarkers (lipid, proteins, enzymatic and non-enzymatic antioxidant systems), and histopathological alteration in brain tissue. Addition of ESA repaired memory impairment, decreased acetylcholinesterase activity, restored oxidative state, and prevented histopathological alteration. In conclusion, the experimental results showed the protective effects of ethanol extract of Syzygium aromaticum against cerium-induced brain damage.

"Programmed Cell Death: A Process of Death for Survival" - How Far Terminology Pertinent for Cell Death in Unicellular Organisms

Programmed cell death (PCD) is genetically regulated phenomenon of selective elimination of target cells that are either under pathological conditions or unwanted for organism’s normal growth and development due to other reasons. The process although being genetically controlled is physiological in nature that renders some hallmarks like blebs in the cell membrane, lobe formation in nuclear membrane, DNA nicks resulting to DNA ladder of 200 bp, and downstream activation of caspases. Moreover, as the process refers to the death of “targeted cell”, the term is exclusively suitable for multicellular organisms. Number of reports advocate similar type of cell death process in unicellular organisms. As cell death in unicellular organisms is also reflected by the signature of PCD obtained in metazoans, such cell death has been grouped under the broad category of PCD. It is pertinent to mention that by definition a unicellular organism is made of a single cell wherein it carries out all of its life processes. Using the term “Programmed Cell Death” with a preset “survival strategy of the organism” for unicellular organisms looks misnomer. Therefore, this correspondence argues and requests recommendation committee on cell death to revisit for the nomenclature of the cell death process in the unicellular organisms.

Ionic stress induces fusion of mitochondria to 3-D networks: An electron tomography study

Mitochondria are central organelles for energy supply of cells and play an important role in maintenance of ionic balance. Consequently mitochondria are highly sensitive to any kind of stress to which they mainly response by disturbance of respiration, ROS production and release of cytochrome c into the cytoplasm. Many of the physiological and molecular stress reactions of mitochondria are well known, yet there is a lack of information on corresponding stress induced structural changes. 3-D visualization of high-pressure frozen cells by FIB-SEM tomography and TEM tomography as used for the present investigation provide an excellent tool for studying structure related mitochondrial stress reactions. In the present study it is shown that mitochondria in the unicellular fresh-water algal model system Micrasterias as well as in the closely related aquatic higher plant Lemna fuse to local networks as a consequence of exposure to ionic stress induced by addition of KCl, NaCl and CoCl₂. In dependence on concentration and duration of the treatment, fusion of mitochondria occurs either by formation of protuberances arising from the outer mitochondrial membrane, or by direct contact of the surface of elongated mitochondria. As our results show that respiration is maintained in both model systems during ionic stress and mitochondrial fusion, as well as formation of protuberances are reversible, we assume that mitochondrial fusion is a ubiquitous process that may help the cells to cope with stress. This may occur by interconnecting the respiratory chains of the individual mitochondria and by enhancing the buffer capacity against stress induced ionic imbalance.

Stress responsive mitochondrial proteins in Arabidopsis thaliana

In the last decade plant mitochondria have emerged as a target, sensor and initiator of signalling cascades to a variety of stress and adverse growth conditions. A combination of various 'omic profiling approaches combined with forward and reverse genetic studies have defined how mitochondria respond to stress and the signalling pathways and regulators of these responses. Reactive oxygen species (ROS)-dependent and -independent pathways, specific metabolites, complex I dysfunction, and the mitochondrial unfolded protein response (UPR) pathway have been proposed to date. These pathways are regulated by kinases (sucrose non-fermenting response like kinase; cyclin dependent protein kinase E 1) and transcription factors from the abscisic acid-related, WRKY and NAC families. A number of independent studies have revealed that these mitochondrial signalling pathways interact with a variety of phytohormone signalling pathways. While this represents significant progress in the last decade there are more pathways to be uncovered. Post-transcriptional/translational regulation is also a likely determinant of the mitochondrial stress response. Unbiased analyses of the expression of genes encoding mitochondrial proteins in a variety of stress conditions reveal a modular network exerting a high degree of anterograde control. As abiotic and biotic stresses have significant impact on the yield of important crops such as rice, wheat and barley we will give an outlook of how knowledge gained in Arabidopsis may help to increase crop production and how emerging technologies may contribute.

Involvement of CAT in the detoxification of HT-induced ROS burst in rice anther and its relation to pollen fertility

HT-induced ROS burst in developing anther is closely related to the lowered CAT activity as the result of the markedly suppressed OsCATB transcript, thereby causing severe fertility injury for rice plants exposed to HT at meiosis stage. The reproductive stage of rice plants is highly sensitive to heat stress. In this paper, different rice cultivars were used to investigate the relationship of HT-induced floret sterility with reactive oxygen species (ROS) detoxification in rice anthers under well-controlled climatic conditions. Results showed that high temperature (HT) exposure significantly enhanced the ROS level and malondialdehyde (MDA) content in developing anther, and the increase in ROS amount in rice anther under HT exposure was closely associated with HT-induced decline in the activities of several antioxidant enzymes. For various antioxidant enzymes, SOD and CAT were more susceptible to the ROS burst in rice anther induced by HT exposure than APX and POD, in which SOD and CAT activity in developing anther decreased significantly by HT exposure, whereas APX activity was relatively stable among different temperature regimes. HT-induced decrease in CAT activity was attributable to the suppressed transcript of OsCATB. This occurrence was strongly responsible for HT-induced increase in ROS level and oxidative-damage in rice anther, thereby it finally caused significant reduction in pollen viability and floret fertility for the rice plants exposed to HT during meiosis. Exogenous application of 1000 µM salicylic acid (SA) may alleviate HT-induced reduction in pollen viability and floret fertility, concomitantly with the increased CAT activity and reduced ROS level in rice anther.

Characterization of the Mitochondrial Aerobic Metabolism in the Pre- and Perisynaptic Districts of the SOD1G93A Mouse Model of Amyotrophic Lateral Sclerosis

Amyotrophic lateral sclerosis (ALS) is an adult-onset fatal neurodegenerative disease characterized by muscle wasting, weakness, and spasticity due to a progressive degeneration of cortical, brainstem, and spinal motor neurons. The etiopathological causes are still largely obscure, although astrocytes definitely play a role in neuronal damage. Several mechanisms have been proposed to concur to neurodegeneration in ALS, including mitochondrial dysfunction. We have previously shown profound modifications of glutamate release and presynaptic plasticity in the spinal cord of the SOD1^G93A mouse model of ALS. In this work, we characterized, for the first time, the aerobic metabolism in two specific compartments actively involved in neurotransmission (i.e. the presynaptic district, using purified synaptosomes, and the perisynaptic astrocyte processes, using purified gliosomes) in SOD1^G93A mice at different stages of the disease. ATP/AMP ratio was lower in synaptosomes isolated from the spinal cord, but not from other brain areas, of SOD1^G93A vs. control mice. The energy impairment was linked to altered oxidative phosphorylation (OxPhos) and increment of lipid peroxidation. These metabolic dysfunctions were present during disease progression, starting at the very pre-symptomatic stages, and did not depend on a different number of mitochondria or a different expression of OxPhos proteins. Conversely, gliosomes showed a reduction of the ATP/AMP ratio only at the late stages of the disease and an increment of oxidative stress also in the absence of a significant decrement in OxPhos activity. Data suggest that the presynaptic neuronal moiety plays a pivotal role for synaptic energy metabolism dysfunctions in ALS. Changes in the perisynaptic compartment seem subordinated to neuronal damage.

De novo transcriptome sequencing and comprehensive analysis of the heat stress response genes in the basidiomycetes fungus Ganoderma lucidum

Ganoderma lucidum is a valuable basidiomycete with numerous pharmacological compounds, which is widely consumed throughout China. We previously found that the polysaccharide content of Ganoderma lucidum fruiting bodies could be significantly improved by 45.63% with treatment of 42 °C heat stress (HS) for 2 h. To further investigate genes involved in HS response and explore the mechanisms of HS regulating the carbohydrate metabolism in Ganoderma lucidum, high-throughput RNA-Seq was conducted to analyse the difference between control and heat-treated mycelia at transcriptome level. We sequenced six cDNA libraries with three from control group (mycelia cultivated at 28 °C) and three from heat-treated group (mycelia subjected to 42 °C for 2 h). A total of 99,899 transcripts were generated using Trinity method and 59,136 unigenes were annotated by seven public databases. Among them, 2790 genes were identified to be differential expressed genes (DEGs) under HS condition, which included 1991 up-regulated and 799 down-regulated. 176 DEGs were then manually classified into five main responsive-related categories according to their putative functions and possible metabolic pathways. These groups include stress resistance-related factors; protein assembly, transportation and degradation; signal transduction; carbohydrate metabolism and energy provision-related process; other related functions, suggesting that a series of metabolic pathways in Ganoderma lucidum are activated by HS and the response mechanism involves a complex molecular network which needs further study. Remarkably, 48 DEGs were found to regulate carbohydrate metabolism, both in carbohydrate hydrolysis for energy provision and polysaccharide synthesis. In summary, this comprehensive transcriptome analysis will provide enlarged resource for further investigation into the molecular mechanisms of basidiomycete under HS condition.

Photo-modulation of programmed cell death in rice leaves triggered by salinity

In this paper we provide evidence for involvement of chloroplast as alternate organelle for initiating PCD in plants under light and abiotic stress. In animals, mitochondria are the major source of reactive oxygen species (ROS) and key executioner of programmed cell death (PCD). In plants, however, the primary site of generation of ROS is chloroplast and yet its involvement in PCD has not been worked out in details. We found by Evans blue staining that salt (150 mM NaCl)-treated protoplasts obtained from green seedlings had higher rate of cell death than protoplasts obtained from etiolated seedlings. This indicated that cell death induced by NaCl is accentuated by light. Imposition of salt-stress to green protoplasts generated H₂O₂. Known hallmarks of PCD i.e., blebbing of cell membrane, loabing in nucleus, nick in DNA were observed in light-exposed salt-treated protoplasts and seedlings. TUNEL-FACS assay demonstrate several DNA nicks in the salt-treated green protoplasts exposed to light. Conversely, salt-treated etiolated protoplasts kept in dark had only a few TUNEL-positive nuclei. Similarly, a substantial numbers of TUNEL positive nuclei were observed in green seedlings due to salt treatment in light. However, salt-treated etiolated seedlings kept in dark had very few TUNEL positive nuclei. Addition of Caspase 3 inhibitor (DAVD-CHO) rescued (~50 %) green protoplasts from salt-stress induced cell death suggesting an involvement of apoptosis like PCD (AL-PCD). Ultra structure studies of chloroplast, mitochondria and nucleus from the leaves obtained from salt treated seedlings at the time point that showed PCD signature, resulted to severe granal de-stacking in chloroplasts while structural integrity of mitochondria was maintained. These studies demonstrate the photo-modulation of salinity-induced PCD in photosynthetic tissues is mainly executed by chloroplasts.

Exogenous Hydrogen Peroxide Contributes to Heme Oxygenase-1 Delaying Programmed Cell Death in Isolated Aleurone Layers of Rice Subjected to Drought Stress in a cGMP-Dependent Manner

Hydrogen peroxide (H2O2) is a reactive oxygen species (ROS) that plays a dual role in plant cells. Here, we discovered that drought (20% polyethylene glycol-6000, PEG)-triggered decreases of HO-1 transcript expression and HO activity. However, exogenous H2O2 contributed toward the increase in HO-1 gene expression and activity of the enzyme under drought stress. Meanwhile, the HO-1 inducer hematin could mimic the effects of the H2O2 scavengers ascorbic acid (AsA) and dimethylthiourea (DMTU) and the H2O2 synthesis inhibitor diphenyleneiodonium (DPI) for scavenging or diminishing drought-induced endogenous H2O2. Conversely, the zinc protoporphyrin IX (ZnPPIX), an HO-1-specific inhibitor, reversed the effects of hematin. We further analyzed the endogenous H2O2 levels and HO-1 transcript expression levels of aleurone layers treated with AsA, DMTU, and DPI in the presence of exogenous H2O2 under drought stress, respectively. The results showed that in aleurone layers subjected to drought stress, when the endogenous H2O2 level was inhibited, the effect of exogenous H2O2 on the induction of HO-1 was enhanced. Furthermore, exogenous H2O2-activated HO-1 effectively enhanced amylase activity. Application of 8-bromoguanosine 3',5'-cyclic guanosine monophosphate (8-Br-cGMP) (the membrane permeable cGMP analog) promoted the effect of exogenous H2O2-delayed PCD of aleurone layers in response to drought stress. More importantly, HO-1 delayed the programmed cell death (PCD) of aleurone layers by cooperating with nitric oxide (NO), and the delayed effect of NO on PCD was achieved via mediation by cGMP under drought stress. In short, in rice aleurone layers, exogenous H2O2 (as a signaling molecule) triggered HO-1 and delayed PCD via cGMP which possibly induced amylase activity under drought stress. In contrast, as a toxic by-product of cellular metabolism, the drought-generated H2O2 promoted cell death.

Identification of Proteins Involved in Carbohydrate Metabolism and Energy Metabolism Pathways and Their Regulation of Cytoplasmic Male Sterility in Wheat

Cytoplasmic male sterility (CMS) where no functional pollen is produced has important roles in wheat breeding. The anther is a unique organ for male gametogenesis and its abnormal development can cause male sterility. However, the mechanisms and regulatory networks related to plant male sterility are poorly understood. In this study, we conducted comparative analyses using isobaric tags for relative and absolute quantification (iTRAQ) of the pollen proteins in a CMS line and its wheat maintainer. Differentially abundant proteins (DAPs) were analyzed based on Gene Ontology classifications, metabolic pathways and transcriptional regulation networks using Blast2GO. We identified 5570 proteins based on 23,277 peptides, which matched with 73,688 spectra, including proteins in key pathways such as glyceraldehyde-3-phosphate dehydrogenase, pyruvate kinase and 6-phosphofructokinase 1 in the glycolysis pathway, isocitrate dehydrogenase and citrate synthase in the tricarboxylic acid cycle and nicotinamide adenine dinucleotide (NADH)-dehydrogenase and adenosine-triphosphate (ATP) synthases in the oxidative phosphorylation pathway. These proteins may comprise a network that regulates male sterility in wheat. Quantitative real time polymerase chain reaction (qRT-PCR) analysis, ATP assays and total sugar assays validated the iTRAQ results. These DAPs could be associated with abnormal pollen grain formation and male sterility. Our findings provide insights into the molecular mechanism related to male sterility in wheat.

Relationship of ROS accumulation and superoxide dismutase isozymes in developing anther with floret fertility of rice under heat stress

High temperature (HT) at meiosis stage is one of most important environment constraint affecting spikelet fertility and rice yield. In this paper, the effects of HT exposure at meiosis stage on the ROS (reactive oxygen species) accumulation, various superoxide dismutase (SOD, EC1.15.1.11) isozymes in developing anther, and its relationship with HT-induced decline in pollen viability and floret fertility were investigated by using four rice cultivars differing in heat tolerance under well-controlled climatic condition. Results showed that HT exposure significantly increased ROS level and malondialdehyde (MDA) content in rice anther, and this occurrence was strongly responsible for the HT-induced decline in pollen viability and harmful effect of HT adversity on floret fertility. However, the increased extent of ROS concentration in rice anther under HT exposure was greatly variable, depending on both the intensity and duration of HT exposure and different rice cultivars used. The SOD and CAT activities of HT-sensitive cultivars decreased more profoundly than those of HT-tolerant cultivars under the same HT regimes. Among various types of SOD enzymes, Cu/Zn-SODa expressed highly in rice anther and responded sensitively to HT exposure, while Cu/Zn-SODb expressed weakly in rice anther and preferentially in rice leaves. HT exposure suppressed the expression of Cu/Zn-SODa in developing anther, which was closely associated with the down-regulated transcripts of cCu/Zn-SOD1 gene. Hence, Cu/Zn-SODa may play a central role in the regulation of total SOD activity and ROS detoxification in rice anther as affected by HT exposure at meiosis stage.

Mitochondrial dynamics and respiration within cells with increased open pore cytoskeletal meshes

The cytoskeletal architecture directly affects the morphology, motility, and tensional homeostasis of the cell. In addition, the cytoskeleton is important for mitosis, intracellular traffic, organelle motility, and even cellular respiration. The organelle responsible for a majority of the energy conversion for the cell, the mitochondrion, has a dependence on the cytoskeleton for mobility and function. In previous studies, we established that cytoskeletal inhibitors altered the movement of the mitochondria, their morphology, and their respiration in human dermal fibroblasts. Here, we use this protocol to investigate applicability of power law diffusion to describe mitochondrial locomotion, assessment of rates of fission and fusion in healthy and diseased cells, and differences in mitochondria locomotion in more open networks either in response to cytoskeletal destabilizers or by cell line. We found that mitochondria within fibrosarcoma cells and within fibroblast cells treated with an actin-destabilizing toxin resulted in increased net travel, increased average velocity, and increased diffusion of mitochondria when compared to control fibroblasts. Although the mitochondria within the fibrosarcoma travel further than mitochondria within their healthy counterparts, fibroblasts, the dependence on mitochondria for respiration is much lower with higher rates ofhydrogen peroxide production and was confirmed using the OROBOROS O2K. We also found that rates of fission and fusion of the mitochondria equilibrate despite significant alteration of the cytoskeleton. Rates ranged from 15% to 25%, where the highest rates were observed within the fibrosarcoma cell line. This result is interesting because the fibrosarcoma cell line does not have increased respiration metrics including when compared to fibroblast. Mitochondria travel further, faster, and have an increase in percent mitochondria splitting or joining while not dependent on the mitochondria for a majority of its energy production. This study illustrates the complex interaction between mitochondrial movement and respiration through the disruption of the cytoskeleton.

Summary: We assessed the effect of cytoskeletal inhibitors and the use of a calcium ionophore as an additional stressor on mitochondrial motility and bioenergetic function in fibroblasts and fibrosarcoma cells.

Ameliorative effect of black ginseng extract against oxidative stress-induced cellular damages in mouse hepatocytes

Background

Oxidative stress induces the production of reactive oxygen species (ROS), which play important causative roles in various pathological conditions. Black ginseng (BG), a type of steam-processed ginseng, has drawn significant attention due to its biological activity, and is more potent than white ginseng (WG) or red ginseng (RG).

Methods

We evaluated the protective effects of BG extract (BGE) against oxidative stress-induced cellular damage, in comparison with WG extract (WGE) and RG extract (RGE) in a cell culture model. Ethanolic extracts of WG, RG, and BG were used to evaluate ginsenoside profiles, total polyphenols, flavonoid contents, and antioxidant activity. Using AML-12 cells treated with H₂O₂, the protective effects of WGE, RGE, and BGE on cellular redox status, DNA, protein, lipid damage, and apoptosis levels were investigated.

Results

BGE exhibited significantly enhanced antioxidant potential, as well as total flavonoid and polyphenol contents. ATP levels were significantly higher in BGE-treated cells than in control; ROS generation and glutathione disulfide levels were lower but glutathione (GSH) and NADPH levels were higher in BGE-treated cells than in other groups. Pretreatment with BGE inhibited apoptosis and therefore protected cells from oxidative stress-induced cellular damage, probably through ROS scavenging.

Conclusion

Collectively, our results demonstrate that BGE protects AML-12 cells from oxidative stress-induced cellular damages more effectively than WGE or RGE, through ROS scavenging, maintenance of redox status, and activation of the antioxidant defense system.

Hyperglycemia exacerbates downregulation of dynamin-like protein 1 in ischemic cerebral injury

Ischemic stroke is one of the leading causes of adult disability and death. Hyperglycemia is associated with an increased risk of stroke and poor outcomes after brain injury. Dynamin-like protein I (DLP-1) regulates mitochondrial fission and promotes mitochondrial dynamics. Neurodegenerative diseases are associated with mitochondrial dysfunction, and the downregulation of DLP-1 has been previously identified in a stroke animal model. Here, we investigated the changes in DLP-1 protein expression in an animal model of focal cerebral ischemia with induced hyperglycemia. Streptozotocin (40 mg/kg) was intraperitoneally injected into male rats to induce hyperglycemia, and middle cerebral artery occlusion (MCAO) was surgically induced 4 weeks after streptozotocin treatment. Brain tissue was isolated 24 hours after MCAO, and cerebral cortex samples were used for this study. Proteomics revealed a decrease in DLP-1 expression in MCAO animals when compared with controls, and this downregulation was more prominent in MCAO animals with hyperglycemia. Reverse-transcription polymerase chain reaction and Western blot analyses confirmed that DLP-1 was significantly downregulated in MCAO-injured animals with hyperglycemia compared to those without hyperglycemia. The decrease in DLP-1 indicates mitochondrial morphological changes and dysfunction. Together, these results suggest that the severe decrease of DLP-1 seen after brain injury under hyperglycemic conditions may exacerbate the damage to the brain.

Proteomic analysis reveals strong mitochondrial involvement in cytoplasmic male sterility of pepper (Capsicum annuum L.)

Although cytoplasmic male sterility (CMS) is widely used for developing pepper hybrids, its molecular mechanism remains unclear. In this study, we used a high-throughput proteomics method called label-free to compare protein abundance across a pepper CMS line (A-line) and its isogenic maintainer line (B-line). Data are available via ProteomeXchange with identifier PXD006104. Approximately 324 differentially abundant protein species were identified and quantified; among which, 47 were up-accumulated and 140 were down-accumulated in the A-line; additionally, 75 and 62 protein species were specifically accumulated in the A-line and B-line, respectively. Protein species involved in pollen exine formation, pyruvate metabolic processes, the tricarboxylic acid cycle, the mitochondrial electron transport chain, and oxidative stress response were observed to be differentially accumulated between A-line and B-line, suggesting their potential roles in the regulation of pepper pollen abortion. Based on our data, we proposed a potential regulatory network for pepper CMS that unifies these processes.

BIOLOGICAL SIGNIFICANCE

Artificial emasculation is a major obstacle in pepper hybrid breeding for its high labor cost and poor seed purity. While the use of cytoplasmic male sterility (CMS) in hybrid system is seriously frustrated because a long time is needed to cultivate male sterility line and its isogenic restore line. Transgenic technology is an effective and rapid method to obtain male sterility lines and its widely application has very important significance in speeding up breeding process in pepper. Although numerous studies have been conducted to select the genes related to male sterility, the molecular mechanism of cytoplasmic male sterility in pepper remains unknown. In this study, we used the high-throughput proteomic method called "label-free", coupled with liquid chromatography-quadrupole mass spectrometry (LC-MS/MS), to perform a novel comparison of expression profiles in a CMS pepper line and its maintainer line. Based on our results, we proposed a potential regulated protein network involved in pollen development as a novel mechanism of pepper CMS.

Characterization of Adipogenic Activity of House Dust Extracts and Semi-Volatile Indoor Contaminants in 3T3-L1 Cells

Obesity and metabolic disorders are of great societal concern and generate significant human health care costs. Recently, attention has focused on the potential for environmental contaminants to act as metabolic disruptors. This study sought to evaluate the adipogenic activity of indoor house dust extracts and a suite of semivolatile organic chemicals (SVOCs) that are often ubiquitously detected in indoor environments. 3T3-L1 cells were exposed to extracts of indoor dust or individual SVOCs and assessed for triglyceride accumulation and preadipocyte proliferation. Ten of 11 house dust extracts exhibited significant triglyceride accumulation and/or proliferation at environmentally relevant levels (<20 μg of dust/well), and significant adipogenic activity was also exhibited by 28 of the SVOCs. Notably, pyraclostrobin, dibutyl phthalate, tert-butyl-phenyl diphenyl phosphate, and the isopropylated triaryl phosphates (ITPs) exhibited near maximal or supra-maximal triglyceride accumulation relative to the rosiglitazone-induced maximum. The adipogenic activity in house dust occurred at concentrations below EPA estimated child exposure levels, and raises concerns for human health impacts, particularly in children. Our results delineate a novel potential health threat and identify putative causative SVOCs that are likely contributing to this activity.

Polymer nanoassemblies with hydrophobic pendant groups in the core induce false positive siRNA transfection in luciferase reporter assays

Poly(ethylene glycol)-conjugated polyethylenimine (PEG-PEI) is a widely studied cationic polymer used to develop non-viral vectors for siRNA therapy of genetic disorders including cancer. Cell lines stably expressing luciferase reporter protein typically evaluate the transfection efficacy of siRNA/PEG-PEI complexes, however recent findings revealed that PEG-PEI can reduce luciferase expression independent of siRNA. This study elucidates a cause of the false positive effect in luciferase assays by using polymer nanoassemblies (PNAs) made from PEG, PEI, poly-(l-lysine) (PLL), palmitate (PAL), and deoxycholate (DOC): PEG-PEI (2P), PEG-PEI-PAL (3P), PEG-PLL (2P'), PEG-PLL-PAL (3P'), and PEG-PEI-DOC (2PD). In vitro transfection and western blot assays of luciferase using a colorectal cancer cell line expressing luciferase (HT29/LUC) concluded that 2P and 2P' caused no luciferase expression reduction while hydrophobically modified PNAs induced a 35-50% reduction (3P'<2PD<3P). Although cell viability remained stagnant, 3P triggered cellular stress responses including increased membrane porosity and decreased ATP and cellular protein concentrations. Raman spectroscopy suggested that hydrophobic groups influence PNA conformation changes, which may have caused over-ubiquitination and degradation of luciferase in the cells. These results indicate that hydrophobically modified PEG-PEI induces cellular distress causing over-ubiquitination of the luciferase protein, producing false positive siRNA transfection in the luciferase assay.

iTRAQ Mitoproteome Analysis Reveals Mechanisms of Programmed Cell Death in Arabidopsis thaliana Induced by Ochratoxin A

Ochratoxin A (OTA) is one of the most common and dangerous mycotoxins in the world. Previous work indicated that OTA could elicit spontaneous HR-like lesions formation Arabidopsis thaliana, reactive oxygen species (ROS) play an important role in OTA toxicity, and their major endogenous source is mitochondria. However, there has been no evidence as to whether OTA induces directly PCD in plants until now. In this study, the presence of OTA in Arabidopsisthaliana leaves triggered accelerated respiration, increased production of mitochondrial ROS, the opening of ROS-dependent mitochondrial permeability transition pores and a decrease in mitochondrial membrane potential as well as the release of cytochrome c into the cytosol. There were 42 and 43 significantly differentially expressed proteins identified in response to exposure to OTA for 8 and 24 h, respectively, according to iTRAQ analysis. These proteins were mainly involved in perturbation of the mitochondrial electron transport chain, interfering with ATP synthesis and inducing PCD. Digital gene expression data at transcriptional level was consistent with the cell death induced by OTA being PCD. These results indicated that mitochondrial dysfunction was a prerequisite for OTA-induced PCD and the initiation and execution of PCD via a mitochondrial-mediated pathway.

The Arabidopsis Mitochondrial Protease FtSH4 Is Involved in Leaf Senescence via Regulation of WRKY-Dependent Salicylic Acid Accumulation and Signaling

Mitochondria and autophagy play important roles in the networks that regulate plant leaf senescence and cell death. However, the molecular mechanisms underlying the interactions between mitochondrial signaling and autophagy are currently not well understood. This study characterized the function of the Arabidopsis (Arabidopsis thaliana) mitochondrial AAA-protease gene FtSH4 in regulating autophagy and senescence, finding that FtSH4 mediates WRKY-dependent salicylic acid (SA) accumulation and signaling. Knockout of FtSH4 in the ftsh4-4 mutant resulted in severe leaf senescence, cell death, and high autophagy levels. The level of SA increased dramatically in the ftsh4-4 mutant. Expression of nahG in the ftsh4-4 mutant led to decreased SA levels and suppressed the leaf senescence and cell death phenotypes. The transcript levels of several SA synthesis and signaling genes, including SALICYLIC ACIDINDUCTION DEFICIENT2 (SID2), NON-RACE-SPECIFIC DISEASE RESISTANCE1 (NDR1), and NONEXPRESSOR OF PATHOGENESIS-RELATED PROTEINS1 (NPR1), increased significantly in the ftsh4-4 mutants compared with the wild type. Loss of function of SID2, NDR1, or NPR1 in the ftsh4-4 mutant reversed the ftsh4-4 senescence and autophagy phenotypes. Furthermore, ftsh4-4 mutants had elevated levels of transcripts of several WRKY genes, including WRKY40, WRKY46, WRKY51, WRKY60, WRKY63, and WRKY75; all of these WRKY proteins can bind to the promoter of SID2 Loss of function of WRKY75 in the ftsh4-4 mutants decreased the levels of SA and reversed the senescence phenotype. Taken together, these results suggest that the mitochondrial ATP-dependent protease FtSH4 may regulate the expression of WRKY genes by modifying the level of reactive oxygen species and the WRKY transcription factors that control SA synthesis and signaling in autophagy and senescence.

Reduction of oxidative-nitrosative stress underlies anticataract effect of topically applied tocotrienol in streptozotocin-induced diabetic rats

Cataract, a leading cause of blindness, is of special concern in diabetics as it occurs at earlier onset. Polyol accumulation and increased oxidative-nitrosative stress in cataractogenesis are associated with NFκB activation, iNOS expression, ATP depletion, loss of ATPase functions, calpain activation and proteolysis of soluble to insoluble proteins. Tocotrienol was previously shown to reduce lens oxidative stress and inhibit cataractogenesis in galactose-fed rats. In current study, we investigated anticataract effects of topical tocotrienol and possible mechanisms involved in streptozotocin-induced diabetic rats. Diabetes was induced in Sprague Dawley rats by intraperitoneal injection of streptozotocin. Diabetic rats were treated with vehicle (DV) or tocotrienol (DT). A third group consists of normal, non-diabetic rats were treated with vehicle (NV). All treatments were given topically, bilaterally, twice daily for 8 weeks with weekly slit lamp monitoring. Subsequently, rats were euthanized and lenses were subjected to estimation of polyol accumulation, oxidative-nitrosative stress, NFκB activation, iNOS expression, ATP levels, ATPase activities, calpain activity and total protein levels. Cataract progression was delayed from the fifth week onwards in DT with lower mean of cataract stages compared to DV group (p<0.01) despite persistent hyperglycemia. Reduced cataractogenesis in DT group was accompanied with lower aldose reductase activity and sorbitol level compared to DV group (p<0.01). DT group also showed reduced NFκB activation, lower iNOS expression and reduced oxidative-nitrosative stress compared to DV group. Lenticular ATP and ATPase and calpain 2 activities in DT group were restored to normal. Consequently, soluble to insoluble protein ratio in DT group was higher compared to DV (p<0.05). In conclusion, preventive effect of topical tocotrienol on development of cataract in STZ-induced diabetic rats could be attributed to reduced lens aldose reductase activity, polyol levels and oxidative-nitrosative stress. These effects of tocotrienol invlove reduced NFκB activation, lower iNOS expression, restoration of ATP level, ATPase activities, calpain activity and lens protein levels.

Alterations in rice chloroplast integrity, photosynthesis and metabolome associated with pathogenesis of Rhizoctonia solani

Sheath blight disease is caused by a necrotrophic fungal pathogen Rhizoctonia solani and it continues to be a challenge for sustainable rice cultivation. In this study, we adopted a multi-pronged approach to understand the intricacies of rice undergoing susceptible interactions with R. solani. Extensive anatomical alteration, chloroplast localized ROS, deformed chloroplast ultrastructure along with decreased photosynthetic efficiency were observed in infected tissue. GC-MS based metabolite profiling revealed accumulation of glycolysis and TCA cycle intermediates, suggesting enhanced respiration. Several aromatic and aliphatic amino acids along with phenylpropanoid intermediates were also accumulated, suggesting induction of secondary metabolism during pathogenesis. Furthermore, alterations in carbon metabolism along with perturbation of hormonal signalling were highlighted in this study. The gene expression analysis including RNAseq profiling reinforced observed metabolic alterations in the infected tissues. In conclusion, the present study unravels key events associated during susceptible rice-R. solani interactions and identifies metabolites and transcripts that are accumulated in infected tissues.

Lasalocid induces cytotoxic apoptosis and cytoprotective autophagy through reactive oxygen species in human prostate cancer PC-3 cells

Lasalocid is an antibiotic from the group of carboxylic ionophores, produced by Streptomyces lasaliensis. But there was limited information of lasalocid on human prostate cancer cells. In the present studies, to better understand its effect in human prostate cancer cells, apoptosis and autophagy associated with possible signal pathways in vitro was examined. Our study showed that lasalocid mediated cell cycle arrest in G₀/G₁ phase by reducing G₁ phase dependent proteins, indicating entering into apoptotic cell death pathway. Lasalocid-induced apoptosis was involved with reactive oxygen species (ROS) production, and mitochondrial hyperpolarization. In addition, lasalocid induced autophagy through microtubule-associated protein 1 light chain 3 (LC-3)-II conversion, acidic vesicular organelles formation and GFP-LC-3 punctuate, which was inhibited by 3-methyladenine (3-MA), a widely used pharmacological inhibitor of autophagy. Furthermore, the autophagic phenomena were mediated by production of ROS, confirming that inhibition of ROS with N-acetyl-l-cysteine, a ROS inhibitor, attenuated lasalocid-triggered autophagy. Inhibition of autophagy with 3-MA enhanced the lasalocid-induced apoptosis through enhanced ROS generation. Taken together, lasalocid should be useful in the search for new potential chemotherapeutic agents for understanding the molecular mechanisms of anticancer in prostate cancer cells.

Withania somnifera Root Extract Enhances Chemotherapy through 'Priming'

Withania somnifera extracts are known for their anti-cancerous, anti-inflammatory and antioxidative properties. One of their mechanisms of actions is to modulate mitochondrial function through increasing oxidative stress. Recently 'priming' has been suggested as a potential mechanism for enhancing cancer cell death. In this study we demonstrate that 'priming', in HT-29 colon cells, with W. somnifera root extract increased the potency of the chemotherapeutic agent cisplatin. We have also showed the W. somnifera root extract enhanced mitochondrial dysfunction and that the underlying mechanism of 'priming' was selectively through increased ROS. Moreover, we showed that this effect was not seen in non-cancerous cells.

Antarctic Moss Multiprotein Bridging Factor 1c Overexpression in Arabidopsis Resulted in Enhanced Tolerance to Salt Stress

Polytrichastrum alpinum is one of the moss species that survives extreme conditions in the Antarctic. In order to explore the functional benefits of moss genetic resources, P. alpinum multiprotein-bridging factor 1c gene (PaMBF1c) was isolated and characterized. The deduced amino acid sequence of PaMBF1c comprises of a multiprotein-bridging factor (MBF1) domain and a helix-turn-helix (HTH) domain. PaMBF1c expression was induced by different abiotic stresses in P. alpinum, implying its roles in stress responses. We overexpressed PaMBF1c in Arabidopsis and analyzed the resulting phenotypes in comparison with wild type and/or Arabidopsis MBF1c (AtMBF1c) overexpressors. Overexpression of PaMBF1c in Arabidopsis resulted in enhanced tolerance to salt and osmotic stress, as well as to cold and heat stress. More specifically, enhanced salt tolerance was observed in PaMBF1c overexpressors in comparison to wild type but not clearly observable in AtMBF1c overexpressing lines. Thus, these results implicate the evolution of PaMBF1c under salt-enriched Antarctic soil. RNA-Seq profiling of NaCl-treated plants revealed that 10 salt-stress inducible genes were already up-regulated in PaMBF1c overexpressing plants even before NaCl treatment. Gene ontology enrichment analysis with salt up-regulated genes in each line uncovered that the terms lipid metabolic process, ion transport, and cellular amino acid biosynthetic process were significantly enriched in PaMBF1c overexpressors. Additionally, gene enrichment analysis with salt down-regulated genes in each line revealed that the enriched categories in wild type were not significantly overrepresented in PaMBF1c overexpressing lines. The up-regulation of several genes only in PaMBF1c overexpressing lines suggest that enhanced salt tolerance in PaMBF1c-OE might involve reactive oxygen species detoxification, maintenance of ATP homeostasis, and facilitation of Ca²⁺ signaling. Interestingly, many salt down-regulated ribosome- and translation-related genes were not down-regulated in PaMBF1c overexpressing lines under salt stress. These differentially regulated genes by PaMBF1c overexpression could contribute to the enhanced tolerance in PaMBF1c overexpressing lines under salt stress.

Melatonin Protects Cultured Tobacco Cells against Lead-Induced Cell Death via Inhibition of Cytochrome c Translocation

Melatonin was discovered in plants more than two decades ago and, especially in the last decade, it has captured the interests of plant biologists. Beyond its possible participation in photoperiod processes and its role as a direct free radical scavenger as well as an indirect antioxidant, melatonin is also involved in plant defense strategies/reactions. However, the mechanisms that this indoleamine activates to improve plant stress tolerance still require identification and clarification. In the present report, the ability of exogenous melatonin to protect Nicotiana tabacum L. line Bright Yellow 2 (BY-2) suspension cells against the toxic exposure to lead was examined. Studies related to cell proliferation and viability, DNA fragmentation, possible translocation of cytochrome c from mitochondria to cytosol, cell morphology after fluorescence staining and also the in situ accumulation of superoxide radicals measured via the nitro blue tetrazolium reducing test, were conducted. This work establishes a novel finding by correcting the inhibition of release of mitochondrial ctytocrome c in to the cytoplasm with the high accumulation of superoxide radicals. The results show that pretreatment with 200 nm of melatonin protected tobacco cells from DNA damage caused by lead. Melatonin, as an efficacious antioxidant, limited superoxide radical accumulation as well as cytochrome c release thereby, it likely prevents the activation of the cascade of processes leading to cell death. Fluorescence staining with acridine orange and ethidium bromide documented that lead-stressed cells additionally treated with melatonin displayed intact nuclei. The results revealed that melatonin at proper dosage could significantly increase BY-2 cell proliferation and protected them against death. It was proved that melatonin could function as an effective priming agent to promote survival of tobacco cells under harmful lead-induced stress conditions.

Ischemic brain injury decreases dynamin-like protein 1 expression in a middle cerebral artery occlusion animal model and glutamate-exposed HT22 cells

Dynamin-like protein I (DLP-1) is an important mitochondrial fission and fusion protein that is associated with apoptotic cell death in neurodegenerative diseases. In this study, we investigated DLP-1 expression in a focal cerebral ischemia animal model and glutamate-exposed hippocampal-derived cell line. Middle cerebral artery occlusion (MCAO) was surgically induced in adult male rats to induce focal cerebral ischemic injury. Brain tissues were collected 24 hours after the onset of MCAO. MCAO induces an increase in infarct volume and histopathological changes in the cerebral cortex. We identified a decrease in DLP-1 in the cerebral cortices of MCAO-injured animals using a proteomic approach and Western blot analysis. Moreover, glutamate treatment significantly decreased DLP-1 expression in a hippocampal-derived cell line. The decrease in DLP-1 indicates mitochondrial dysfunction. Thus, these results suggest that neuronal cell injury induces a decrease in DLP-1 levels and consequently leads to neuronal cell death.

Cadmium activates both diphenyleneiodonium- and rotenone-sensitive superoxide production in barley root tips

Mild Cd stress-activated diphenyleneiodonium-sensitive superoxide production is utilized in root morphogenic responses, while severe Cd stress-induced robust rotenone-sensitive superoxide generation may lead to cell and root death. In barley, even a few minute exposure of roots to Cd concentration higher than 10 µM evoked a strong superoxide generation in the root transition zone. This superoxide generation was strongly inhibited by the inhibition of mitochondrial electron flow into complex III in the presence of the mitochondrial complex I inhibitor rotenone. Similarly, the superoxide generation induced by antimycin A, an inhibitor of mitochondrial complex III, was considerably reduced by rotenone, suggesting the involvement of complex III also in the severe Cd stress-induced superoxide generation. This severe Cd stress-induced superoxide generation was followed by an extensive cell death in this part of the root tip, which similar to the superoxide generation, was eliminated by rotenone co-treatment. In turn, mild Cd stress-induced diphenyleneiodonium (DPI)-sensitive superoxide generation was observed only in the post-stressed roots, suggesting that it is not directly associated with Cd toxicity. Diphenyleneiodonium, an inhibitor of NADPH oxidase, markedly inhibited the mild Cd stress-induced radial expansion of root apex, indicating that enhanced DPI-sensitive superoxide production is required for rapid isotropic cell growth. Severe Cd stress, probably through the inhibition of complex III, caused a rapid and robust superoxide generation leading to cell and/or root death. By contrast, mild Cd stress did not evoke oxidative stress, and the enhanced DPI-sensitive superoxide generation is utilized in adaptive morphogenic responses.

An 808-nm Diode Laser with a Flat-Top Handpiece Positively Photobiomodulates Mitochondria Activities

OBJECTIVE

Photobiomodulation is proposed as a non-linear process. Only the action of light at a low intensity and fluence is assumed to have stimulation on cells; whereas a higher light intensity and fluence generates negative effects, exhausting the cell's energy reserve as a consequence of a too strong stimulation. In our work, we detected the photobiomodulatory effect of an 808-nm higher-fluence diode laser [64 J/cm²-1 W, continuous wave (CW)] irradiated by a flat-top handpiece on mitochondria activities, such as oxygen consumption, activity of mitochondria complexes I, II, III, and IV, and cytochrome c as well as ATP synthesis.

MATERIALS AND METHODS

The experiments are performed by standard procedure on mitochondria purified from bovine liver.

RESULTS

Our higher-fluence diode laser positively photobiomodulates the mitochondria oxygen consumption, the activity of the complexes III and IV, and the ATP production, with a P/O = 2.6. The other activities are not influenced.

CONCLUSION

Our data show for the first time that even the higher fluences (64 J/cm²-1 W), similar to the low fluences, can photobiostimulate the mitochondria respiratory chain without uncoupling them and can induce an increment in the ATP production. These results suggest that the negative effects of higher fluences observed to date are not unequivocally due to higher fluence per se but might be a consequence of the irradiation carried by handpieces with a Gaussian profile.

Saponin-Based Nanoemulsification Improves the Antioxidant Properties of Vitamin A and E in AML-12 Cells

Our work aimed to investigate the protective effects of saponin-based nanoemulsions of vitamin A and E against oxidative stress-induced cellular damage in AML-12 cells. Saponin nanoemulsions of vitamin A (SAN) and vitamin E (SEN) were prepared by high-pressure homogenization and characterized in terms of size, zeta potential, and polydispersity index. SEN and SAN protect AML-12 cells against oxidative stress-induced cellular damage more efficiently via scavenging reactive oxygen species (ROS), and reducing DNA damage, protein carbonylation, and lipid peroxidation. These results provide valuable information for the development of nanoemulsion-based delivery systems that would improve the antioxidant properties of vitamin A and E.

A novel formaldehyde metabolic pathway plays an important role during formaldehyde metabolism and detoxification in tobacco leaves under liquid formaldehyde stress

Tobacco and Arabidopsis are two model plants often used in botany research. Our previous study indicated that the formaldehyde (HCHO) uptake and assimilation capacities of tobacco leaves were weaker than those of Arabidopsis leaves. After treatment with a 2, 4 or 6 mM HCHO solution for 24 h, detached tobacco leaves absorbed approximately 40% of the HCHO from the treatment solution. (13)C-NMR analysis detected a novel HCHO metabolic pathway in 2 mM H(13)CHO-treated tobacco leaves. [4-(13)C]Asn, [3-(13)C]Gln and [U-(13)C]oxalic acid (OA) were produced from this pathway after H(13)COOH generation during H(13)CHO metabolism in tobacco leaves. Pretreatments of cyclosporin A (CSA) and dark almost completely inhibited the generation of [4-(13)C]Asn, [3-(13)C]Gln and [U-(13)C]OA from this pathway but did not suppressed the production of H(13)COOH in 2 mM H(13)CHO-treated tobacco leaves. The evidence suggests that this novel pathway has an important role during the metabolic detoxification of HCHO in tobacco leaves. The analysis of the chlorophyll and Rubisco contents indicated that CSA and dark pretreatments did not severely affect the survival of leaf cells but significantly inhibited the HCHO uptake by tobacco leaves. Based on the effects of CSA and dark pretreatments on HCHO uptake and metabolism, it is estimated that the contribution of this novel metabolic pathway to HCHO uptake is approximately 60%. The data obtained from the (13)C-NMR analysis revealed the mechanism underlying the weaker HCHO uptake and assimilation of tobacco leaves compared to Arabidopsis leaves.

Dihydroergotamine Tartrate Induces Lung Cancer Cell Death through Apoptosis and Mitophagy

BACKGROUND

Mitochondria have emerged as a major target for anticancer therapy because of their critical role in cancer cell survival. Our preliminary works have suggested that dihydroergotamine tartrate (DHE), an antimigraine agent, may have effects on mitochondria.

METHODS

We examined the effect of DHE on the survival of several lung cancer cells and confirmed that DHE suppressed diverse lung cancer cell growth effectively. To confirm whether such effects of DHE would be associated with mitochondria, A549 cells were employed for the evaluation of several important parameters, such as membrane potential, reactive oxygen species (ROS) generation, apoptosis, ATP production and autophagy.

RESULTS

DHE decreased membrane permeability, increased ROS generation as well as apoptosis, and disturbed ATP production. Eventually, mitophagy was activated for damaged mitochondria.

CONCLUSION

Taken together, our findings demonstrate that DHE induces lung cancer cell death by the induction of apoptosis and mitophagy, thus suggesting that DHE can be developed as an anti-lung cancer therapeutic agent.

Toxicity of cuprizone a Cu(2+) chelating agent on isolated mouse brain mitochondria: a justification for demyelination and subsequent behavioral dysfunction

Multiple Sclerosis (MS) is a complex disease with an unknown etiology and no effective cure, despite decades of extensive research that led to the development of several partially effective treatments. In this study we aimed to investigate brain mitochondrial dysfunction in demyelination induced by cuprizone in mice. Cuprizone was used for induction of demyelination in mice through a diet containing 0.2% w/w cuprizone for 5 weeks. Behavioral tests for proving of MS was performed and then mitochondria from brain of animals were isolated and afterwards parameters of mitochondrial dysfunction examined. Results of mitochondrial dysfunction parameters such as mitochondrial swelling, production ROS, collapse of the membrane potential showed that isolated mitochondria from cuprizone treated mice have been damaged compared to those of untreated control mice. It is likely that demyelination induced mitochondrial damage led to increased mitochondrial ROS formation and progression of oxidative damages in neurons. It is suggested that cuprizone which is a Cu(2+) chelating agent causes impairment of electron transport chain (complex IV) and antioxidant system (SOD) in mitochondria leading to decreased ATP production and increased ROS formation.

Inhibition of cathepsin B by caspase-3 inhibitors blocks programmed cell death in Arabidopsis

Programmed cell death (PCD) is used by plants for development and survival to biotic and abiotic stresses. The role of caspases in PCD is well established in animal cells. Over the past 15 years, the importance of caspase-3-like enzymatic activity for plant PCD completion has been widely documented despite the absence of caspase orthologues. In particular, caspase-3 inhibitors blocked nearly all plant PCD tested. Here, we affinity-purified a plant caspase-3-like activity using a biotin-labelled caspase-3 inhibitor and identified Arabidopsis thaliana cathepsin B3 (AtCathB3) by liquid chromatography with tandem mass spectrometry (LC-MS/MS). Consistent with this, recombinant AtCathB3 was found to have caspase-3-like activity and to be inhibited by caspase-3 inhibitors. AtCathepsin B triple-mutant lines showed reduced caspase-3-like enzymatic activity and reduced labelling with activity-based caspase-3 probes. Importantly, AtCathepsin B triple mutants showed a strong reduction in the PCD induced by ultraviolet (UV), oxidative stress (H₂O₂, methyl viologen) or endoplasmic reticulum stress. Our observations contribute to explain why caspase-3 inhibitors inhibit plant PCD and provide new tools to further plant PCD research. The fact that cathepsin B does regulate PCD in both animal and plant cells suggests that this protease may be part of an ancestral PCD pathway pre-existing the plant/animal divergence that needs further characterisation.