High resistance of Tetrahymena thermophila to paraquat: Mitochondrial alterations, oxidative stress and antioxidant genes expression

Díaz, Silvia; Martín‐González, Ana; Cubas, Liliana; Ortega, Ruth; Amaro, Francisco; Rodríguez-Martín, Daniel; Gutiérrez, Juan-Carlos

doi:10.1016/j.chemosphere.2015.09.010

Cited by 28 publications

(14 citation statements)

References 60 publications

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“…PQ ion binds near ferrodoxin site in the PSI and accepts an electron to form PQ monocation free radical (PQ· + ), which can stop electron transport to NADP + and inhibit normal functioning of PSI. As a result, PQ· + initiates a series of reactions leading to cell membrane disruption and plant death 2 , 3 . Once PQ comes into contact with the soil, it is deactivated and immobilized 4 .…”

Section: Introductionmentioning

confidence: 99%

A user-friendly herbicide derived from photo-responsive supramolecular vesicles

et al. 2018

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Paraquat, as one of the most widely used herbicides globally, is highly toxic to humans, and chronic exposure and acute ingestion leads to high morbidity and mortality rates. Here, we report user-friendly, photo-responsive paraquat-loaded supramolecular vesicles, prepared via one-pot self-assembly of amphiphilic, ternary host-guest complexes between cucurbit[8]uril, paraquat, and an azobenzene derivative. In this vesicle formulation, paraquat is only released upon UV or sunlight irradiation that converts the azobenzene derivative from its trans- to its cis- form, which in turn dissociates the ternary host-guest complexations and the vesicles. The cytotoxicity evaluation of this vesicle formulation of paraquat on in vitro cell models, in vivo zebrafish models, and mouse models demonstrates an enhanced safety profile. Additionally, the PQ-loaded vesicles’ herbicidal activity against a model of invasive weed is nearly identical to that of free paraquat under natural sunlight. This study provides a safe yet effective herbicide formulation.

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Section: Introductionmentioning

confidence: 99%

A user-friendly herbicide derived from photo-responsive supramolecular vesicles

et al. 2018

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“…In general, the TtGPx gene expression induction induced by PQ and CAM is higher after 24 h than after 1 h of treatment. T. thermophila is one of the most resistant/tolerant organisms to PQ (its LC 50 = 32.28 mM) [ 33 ]. The over-expression of the six selected TtGPx genes after prolonged treatment (24 h) supports the role of GPx in the antioxidant response to PQ-induced oxidative stress, as also occurs in plants and animals [ 56 , 57 ].…”

Section: Discussionmentioning

confidence: 99%

“…All metal concentrations used were below their LD 50 (in PP210 medium) [ 31 , 32 ]. (b) Three different oxidative stress inducers: 100 µM H 2 O 2 (Panreac, Barcelona, Spain) 1 h treatment, because at longer exposures, the hydrogen peroxide decomposes to water and oxygen, 2 mM menadione (MD) (Sigma, Saint Louis, MO, USA) only for a 1 h treatment, because at higher exposure times (24 h) the death of the entire cellular population was obtained and 7.7 mM paraquat (PQ) (methyl viologen, Sigma, Saint Louis, MO, USA), 1- and 24-h treatments [ 33 ]. (c) One apoptosis inducer: 0.1 mM camptothecin (CAM) (Calbiochem, Darmstadt, Germany), 1- and 24-h treatments.…”

Section: Methodsmentioning

confidence: 99%

Tetrahymena Glutathione Peroxidase Family: A Comparative Analysis of These Antioxidant Enzymes and Differential Gene Expression to Metals and Oxidizing Agents

et al. 2020

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In the present work, an extensive analysis of the putative glutathione peroxidases (GPx) of the eukaryotic microorganism model Tetrahymena thermophila is carried out. A comparative analysis with GPx present in other Tetrahymena species and other very taxonomically diverse ciliates is also performed. A majority of ciliate GPx have replaced the selenocysteine (Sec) by Cys in its catalytic center, so they can be considered as phospholipid hydroperoxide glutathione peroxidases (PHGPx). Selenocysteine insertion sequence (SECIS) elements have been detected in several ciliate GPx that do not incorporate Sec in their amino acid sequences, and conversely, in other ciliate GPx with Sec, no SECIS elements are detected. These anomalies are analyzed and discussed. From the phylogenetic analysis using the ciliate GPx amino acid sequences, the existence of extensive intra- and interspecific gene duplications that produced multiple GPx isoforms in each species is inferred. The ancestral character of the selenoproteins is also corroborated. The analysis by qRT-PCR of six selected T. thermophila GPx genes has shown a quantitative differential expression between them, depending on the stressor (oxidizing agents, apoptotic inducer or metals) and the time of exposure.

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“…To observe the potential ultrastructural alterations, controls (untreated cells) and cell populations exposed to sublethal treatments of metal(l)oids during 24 h to 0.5 µM Cd, 5 mM As(III) or 25 mM As(V) was analyzed by TEM using previously reported protocols [33,34]. Ultrathin sections were stained with uranyl acetate and lead citrate and, finally, mounted on copper grids and examined with a Jeol JEM 1010 transmission electron microscope operating at 75 kV.…”

Section: Ultrastructural Analysis By Transmission Electron Microscopymentioning

confidence: 99%

Toxicity, Physiological, and Ultrastructural Effects of Arsenic and Cadmium on the Extremophilic Microalga Chlamydomonas acidophila

Díaz

Francisco

Olsson³

et al. 2020

IJERPH

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The cytotoxicity of cadmium (Cd), arsenate (As(V)), and arsenite (As(III)) on a strain of Chlamydomonas acidophila, isolated from the Rio Tinto, an acidic environment containing high metal(l)oid concentrations, was analyzed. We used a broad array of methods to produce complementary information: cell viability and reactive oxygen species (ROS) generation measures, ultrastructural observations, transmission electron microscopy energy dispersive x-ray microanalysis (TEM-XEDS), and gene expression. This acidophilic microorganism was affected differently by the tested metal/metalloid: It showed high resistance to arsenic while Cd was the most toxic heavy metal, showing an LC 50 = 1.94 µM. Arsenite was almost four-fold more toxic (LC 50 = 10.91 mM) than arsenate (LC 50 = 41.63 mM). Assessment of ROS generation indicated that both arsenic oxidation states generate superoxide anions. Ultrastructural analysis of exposed cells revealed that stigma, chloroplast, nucleus, and mitochondria were the main toxicity targets. Intense vacuolization and accumulation of energy reserves (starch deposits and lipid droplets) were observed after treatments. Electron-dense intracellular nanoparticle-like formation appeared in two cellular locations: inside cytoplasmic vacuoles and entrapped into the capsule, around each cell. The chemical nature (Cd or As) of these intracellular deposits was confirmed by TEM-XEDS. Additionally, they also contained an unexpected high content in phosphorous, which might support an essential role of poly-phosphates in metal resistance. development of phytoplankton [5][6][7]. However, most of these studies are related to circumneutral pH water environments polluted by industrial and domestic wastes, in spite of the fact that pH has a considerable effect on the availability and, as a consequence, the toxicity of heavy metals [8].Indeed, many freshwater bodies worldwide are highly acidic (pH < 3), either due to natural causes or anthropogenic activities such as mining [9,10]. Acid drainages are due mainly to pyrite oxidation, producing significant acidity in lakes and ponds situated in areas impacted by mining, as well as in rivers receiving mine water discharge [11,12]. Additionally, extreme acidic environments tend to contain unusually high concentrations of heavy metals because their solubility increases markedly as the pH decreases [11]. Despite these extreme environmental conditions, a number of prokaryotic and eukaryotic organisms living in these extreme environments have been identified [13]. Microalgae are the dominant eukaryotes found in these ecosystems, green microalgae such as Chlamydomonas, Dunaliella, and Chlorella being the main primary producers [13].Although acidophilic algae are able to grow at high heavy metal concentrations and low pH, both of which are lethal to most eukaryotes [14], the adaptive mechanisms by which these microorganisms can survive under such environmental conditions are still poorly understood. Proteomic analysis has pointed out the importance of metal and acidity toleranc...

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High resistance of Tetrahymena thermophila to paraquat: Mitochondrial alterations, oxidative stress and antioxidant genes expression

Cited by 28 publications

References 60 publications

A user-friendly herbicide derived from photo-responsive supramolecular vesicles

A user-friendly herbicide derived from photo-responsive supramolecular vesicles

Tetrahymena Glutathione Peroxidase Family: A Comparative Analysis of These Antioxidant Enzymes and Differential Gene Expression to Metals and Oxidizing Agents

Toxicity, Physiological, and Ultrastructural Effects of Arsenic and Cadmium on the Extremophilic Microalga Chlamydomonas acidophila

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