Cellular Response of Adapted and Non-Adapted Strains to Europium Eu(III) Compounds.

Europium is one of the most reactive lanthanides and humans use it in many different applications, but we still know little about its potential toxicity and cellular response to its exposure. Two strains of the eukaryotic microorganism model were adapted to high concentrations of two Eu(III) compounds (EuCl or EuO) and compared to a control strain and cultures treated with both compounds. In this ciliate, EuCl is more toxic than EuO.

Efficacy and Safety of the Extreme Lateral Interbody Fusion (XLIF) Technique in Spine Surgery: Meta-Analysis of 1409 Patients.

(1) The objective of this study was to quantify the exact clinical-radiological efficacy and safety of the extreme lateral interbody fusion (XLIF) technique in spinal surgery; (2) A meta-analysis was performed using PubMed, Embase, Scopus, and Cochrane Collaboration Library. Studies focusing on patients surgically treated with XLIF were included. The outcomes were as follows: visual analog scale (VAS) and Oswestry disability index (ODI), radiological outcomes, and adverse events.

MicroRNAs in Tetrahymena thermophila: An epigenetic regulatory mechanism in the response to cadmium stress.

Among the epigenetic mechanisms based on non-coding RNA are microRNAs (miRNAs) that are involved in the post-transcriptional regulation of mRNAs. In many organisms, the expression of genes involved in the cellular response to biotic or abiotic stress depends on the regulation, generally inhibitory, performed by miRNAs. For the first time in the eukaryotic microorganism (ciliate-model) Tetrahymena thermophila, miRNAs involved in the post-transcriptional regulation of transcripts linked to the response to cadmium have been isolated and analyzed.

Quantitative proteomic analyses of a Pb-adapted Tetrahymena thermophila strain reveal the cellular strategy to Pb(II) stress including lead biomineralization to chloropyromorphite.

A strain of the protozoan ciliate Tetrahymena thermophila adapted to increasing Pb(II) concentrations over two years has shown that one of the resistance mechanisms to this extreme metal stress is the lead biomineralization to chloropyromorphite, one of the most stable minerals in the earth's crust. Several techniques such as microanalysis coupled to transmission and scanning electron microscopy (X-Ray Energy Disperse Spectroscopy), fluorescence microscopy and X-ray power diffraction analysis have revealed the presence of chloropyromorphite as crystalline aggregates of nano-globular structure, together with the presence of other secondary lead minerals. This is the first time that the existence of this type of biomineralization in a ciliate protozoan is described.

Autophagy and lipid droplets are a defense mechanism against toxic copper oxide nanotubes in the eukaryotic microbial model Tetrahymena thermophila.

The widespread use of inorganic nanomaterials of anthropogenic origin has significantly increased in the last decade, being now considered as emerging pollutants. This makes it necessary to carry out studies to further understand their toxicity and interactions with cells. In the present work we analyzed the toxicity of CuO nanotubes (CuONT) in the ciliate Tetrahymena thermophila, a eukaryotic unicellular model with animal biology.

Arsenate and arsenite differential toxicity in Tetrahymena thermophila.

A comparative analysis of toxicities of both arsenic forms (arsenite and arsenate) in the model eukaryotic microorganism Tetrahymena thermophila (ciliate protozoa) has shown the presence of various detoxification mechanisms and cellular effects comparable to those of animal cells under arsenic stress. In the wild type strain SB1969 arsenate is almost 2.5 times more toxic than arsenite.

Metallic Nanoparticles-Friends or Foes in the Battle against Antibiotic-Resistant Bacteria?

The rapid spread of antibiotic resistances among bacteria demands novel strategies for infection control, and metallic nanoparticles appear as promising tools because of their unique size and tunable properties that allow their antibacterial effects to be maximized. Furthermore, their diverse mechanisms of action towards multiple cell components have suggested that bacteria could not easily develop resistance against nanoparticles. However, research published over the last decade has proven that bacteria can indeed evolve stable resistance mechanisms upon continuous exposure to metallic nanoparticles.

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

In the present work, an extensive analysis of the putative glutathione peroxidases (GPx) of the eukaryotic microorganism model is carried out. A comparative analysis with GPx present in other 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).

Selenium cytotoxicity in Tetrahymena thermophila: New clues about its biological effects and cellular resistance mechanisms.

Selenium is an essential micronutrient but at high concentrations can produce severe cytotoxicity and genomic damage. We have evaluated the cytotoxicity, ultrastructural and mitochondrial alterations of the two main selenium inorganic species; selenite and selenate, in the eukaryotic microorganism Tetrahymena thermophila. In this ciliate, selenite is more toxic than selenate.

AP-1 (bZIP) Transcription Factors as Potential Regulators of Metallothionein Gene Expression in .

Metallothioneins (MT) are multi-stress proteins mainly involved in metal detoxification. MT gene expression is normally induced by a broad variety of stimulus and its gene expression regulation mainly occurs at a transcriptional level. Conserved motifs in the MT promoters have been described.

Genome plasticity in response to stress in Tetrahymena thermophila: selective and reversible chromosome amplification and paralogous expansion of metallothionein genes.

Extreme stress situations can induce genetic variations including genome reorganization. In ciliates like Tetrahymena thermophila, the approximately 45-fold ploidy of the somatic macronucleus may enable adaptive responses that depend on genome plasticity. To identify potential genome-level adaptations related to metal toxicity, we isolated three Tetrahymena thermophila strains after an extended adaptation period to extreme metal concentrations (Cd , Cu or Pb ).

Extreme metal adapted, knockout and knockdown strains reveal a coordinated gene expression among different Tetrahymena thermophila metallothionein isoforms.

Metallothioneins (MT) constitute a superfamily of small cytosolic proteins that are able to bind metal cations through numerous cysteine (Cys) residues. Like other organisms the ciliate Tetrahymena thermophila presents several MT isoforms, which have been classified into two subfamilies (Cd- and Cu-metallothioneins). The main aim of this study was to examine the specific functions and transcriptional regulation of the five MT isoforms present in T.

Stress and Protists: No life without stress.

We report a summary of the symposium "Stress and Protists: No life without stress", which was held in September 2015 on the VII European Congress of Protistology in partnership with the International Society of Protistologists (Seville, Spain). We present an overview on general comments and concepts on cellular stress which can be also applied to any protist. Generally, various environmental stressors may induce similar cell responses in very different protists.

The Tetrahymena metallothionein gene family: twenty-one new cDNAs, molecular characterization, phylogenetic study and comparative analysis of the gene expression under different abiotic stressors.

Background: Ciliate metallothioneins (MTs) are included in family 7 of the MT superfamily. This family has been divided into two main subfamilies: 7a or CdMTs and 7b or CuMTs. All ciliate MTs reported have been isolated from different Tetrahymena species and present unique features with regard to standard MTs.

Influence of an oxic settling anoxic system on biomass yield, protozoa and filamentous bacteria.

An oxic settling anoxic system coupled with an activated sludge process has been studied to reduce sewage sludge production. The reduction of sludge yield, excess sludge production and active biomass yield were 51.7%, 52.

Functional GFP-metallothionein fusion protein from Tetrahymena thermophila: a potential whole-cell biosensor for monitoring heavy metal pollution and a cell model to study metallothionein overproduction effects.

The significance of metal(oid)s as environmental pollutants has made them a priority in ecotoxicology, with the aim of minimizing exposure to animals or humans. Therefore, it is necessary to develop sensitive and inexpensive methods that can efficiently detect and monitor these pollutants in the environment. Conventional analytical techniques suffer from the disadvantages of high cost and complexity.

Whole-cell biosensors for detection of heavy metal ions in environmental samples based on metallothionein promoters from Tetrahymena thermophila.

Heavy metals are among the most serious pollutants, and thus there is a need to develop sensitive and rapid biomonitoring methods for heavy metals in the environment. Critical parameters such as bioavailability, toxicity and genotoxicity cannot be tested using chemical analysis, but only can be assayed using living cells. A whole-cell biosensor uses the whole cell as a single reporter incorporating both bioreceptor and transducer elements.

Double fossilization in eukaryotic microorganisms from Lower Cretaceous amber.

Background: Microfossils are not only useful for elucidating biological macro- and microevolution but also the biogeochemical history of our planet. Pyritization is the most important and extensive mode of preservation of animals and especially of plants. Entrapping in amber, a fossilized resin, is considered an alternative mode of biological preservation.

A pseudo-phytochelatin synthase in the ciliated protozoan Tetrahymena thermophila.

Phytochelatins (PCs) and metallothioneins (MTs) are the two major heavy metal chelating peptides in eukaryotes. We report here on the identification of a biosynthetically inactive pseudo-phytochelatin synthase enzyme (TtpsiPCS) in the ciliate Tetrahymena thermophila, the first of this kind (pseudo-PCS) to be described in eukaryotes. TtpsiPCS which resembles a true PCS at the N-terminal region, while it is most divergent in its Cys-poor C-terminal region, was found to be up-regulated under cadmium stress conditions.

Heavy metals generate reactive oxygen species in terrestrial and aquatic ciliated protozoa.

Reactive oxygen species (ROS) induction by exposure to heavy metals (Cd, Cu or Zn) in diverse free-living ciliated protozoa (Tetrahymena sp. and three strains of Colpoda steinii, isolated from freshwater and soils with different level of metal pollution) has been evaluated. Using specific fluorophores, such as 2',7'-dichlorofluorescein diacetate, hydroethidine and dihydrorhodamine 123, and a fluorescence microscope with the program MetaMorph Imaging System 4.

Two new members of the Tetrahymena multi-stress-inducible metallothionein family: characterization and expression analysis of T. rostrata Cd/Cu metallothionein genes.

We report the cloning and characterization of two new metallothionein (MT) genes (TrosMTT1 and TrosMTT2), isolated as cDNAs, from the ciliated protozoa Tetrahymena rostrata. The TrosMTT1 inferred protein has been identified as a CdMT and included into the 7a subfamily of Tetrahymena MTs, while TrosMTT2 has been identified as a CuMT (including it into 7b subfamily), due to its similarity to TpigMT-2 and its significant induction by copper. TrosMTT1 protein sequence reveals a remarkably regular and hierarchical modular organization, as it is known for other Tetrahymena CdMTs, showing a bi-modular structure.

Evaluation of heavy metal acute toxicity and bioaccumulation in soil ciliated protozoa.

Laboratory toxicity tests, using ciliated protozoa, are scarce and they have been carried out usually with freshwater species. In this study, we have analysed the acute cytotoxicity of Cd, Zn and Cu in five different strains of very common soil ciliate species (Colpoda steinii, Colpoda inflata and Cyrtolophosis elongata), which were isolated from very different soil samples (polluted or not with heavy metals). Soil ciliates are quite resistant to heavy metals pollution with regard to ciliates from other habitats.

Cytotoxicity and bioaccumulation of heavy metals by ciliated protozoa isolated from urban wastewater treatment plants.

We studied the cytotoxic effect of the heavy metals Cd, Zn and Cu on three different species of ciliated protozoa isolated from an urban wastewater treatment plant. The order of toxicity was Cd>Cu>>Zn or Cu>Cd>>Zn, depending on the microbial species. In bimetallic (Cd+Zn) treatments, results indicated that, in general, the presence of Zn in the same medium decreased Cd cytotoxicity.