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Anoop Narayana Pillai, Sushmita Shukla, Sudhanshu Gautam, Abdur Rahaman
Phosphatidate phosphatases (PAH) play a central role in lipid metabolism and intracellular signaling. Herein, we report the presence of a low-molecular-weight PAH homolog in the single-celled ciliate Tetrahymena thermophila. In vitro phosphatase assay showed that TtPAH2 belongs to the magnesium-dependent phosphatidate phosphatase (PAP1) family. Loss of function of TtPAH2 did not affect the growth of Tetrahymena. Unlike other known PAH homologs, TtPAH2 did not regulate lipid droplet number and ER morphology...
December 2017: Journal of Biosciences
Shaon Chakrabarti, Changbong Hyeon, Xiang Ye, George H Lorimer, D Thirumalai
Molecular chaperones facilitate the folding of proteins and RNA in vivo. Under physiological conditions, the in vitro folding of Tetrahymena ribozyme by the RNA chaperone CYT-19 behaves paradoxically; increasing the chaperone concentration reduces the yield of native ribozymes. In contrast, the protein chaperone GroEL works as expected; the yield of the native substrate increases with chaperone concentration. The discrepant chaperone-assisted ribozyme folding thus contradicts the expectation that it operates as an efficient annealing machine...
December 7, 2017: Proceedings of the National Academy of Sciences of the United States of America
Patricia de Francisco, Ana Martín-González, Aaron P Turkewitz, Juan Carlos Gutiérrez
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. thermophila, by using several strains of this ciliate. After a laboratory evolution experiment over more than two years, three different T...
2017: PloS One
María Jesús Andrés-Costa, Kathryn Proctor, Marco T Sabatini, Anthony P Gee, Simon E Lewis, Yolanda Pico, Barbara Kasprzyk-Hordern
European legislation focusing on water quality is expected to broaden to encompass several pharmaceuticals as priority hazardous substances. This manuscript aims to challenge current regulatory approaches that do not recognize stereochemistry of chiral pharmaceuticals by testing the hypothesis that environmental transformation and effects of chiral pharmaceuticals are stereoselective. Our experiments revealed that, while degradation of chiral fluoxetine (FL) in river water occurs via non-enantioselective photochemical and mildly-enantioselective microbial processes favoring the (R)-enantiomer, a pronounced enantioselectivity favoring (S)-FL (leading to the formation of (S)-NFL (norfluoxetine)) is observed during activated sludge treatment...
November 17, 2017: Scientific Reports
Cecília Seixas, João Gonçalves, Luís Viseu Melo, Helena Soares
Cilia are complex and dynamic organelles that have motility and sensory functions. Defects in cilia biogenesis and function are at the origin of human ciliopathies. In motile cilia, a basal body organizes the axoneme composed of nine microtubule doublets surrounding a central pair of singlet microtubules. The distal ends of axonemal microtubules are attached to the membrane by microtubule-capping structures. Little is known about the early steps of cilium assembly. Although cilia grow and resorb from their distal tips, it remains poorly understood where and when the components of the caps are first assembled...
October 20, 2017: Protist
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No abstract text is available yet for this article.
November 2017: Journal of Eukaryotic Microbiology
Jin J Li, Xu J Zhang, Yi Yang, Tao Huang, Chao Li, Limin Su, Yuan H Zhao, Mark T D Cronin
The acute toxicity of organic pollutants to fish, Daphnia magna, Tetrahymena pyriformis, and Vibrio fischeri was investigated. The results indicated that the Toxicity Ratio (TR) threshold of log TR =1, which has been based on the distribution of toxicity data to fish, can also be used to discriminate reactive or specifically acting compounds from baseline narcotics for Daphnia magna and Vibrio fischeri. A log TR=0.84 is proposed for Tetrahymena pyriformis following investigation of the relationships between the species sensitivity and the absolute averaged residuals (AAR) between the predicted baseline toxicity and the experimental toxicity...
November 8, 2017: Science of the Total Environment
Alix M Denoncourt, Valérie E Paquet, Steve J Charette
Mycobacteria are widespread microorganisms that live in various environments, including man-made water systems where they cohabit with protozoa. Environmental mycobacterial species give rise to many opportunistic human infections and can infect phagocytic protozoa. Protozoa such as amoebae and ciliates feeding on bacteria can sometimes get rid of non-digestible or pathogenic material by packaging it into secreted fecal pellets. Usually, packaged bacteria are still viable and are protected against chemical and physical stresses...
November 6, 2017: FEMS Microbiology Letters
Alix M Denoncourt, Alicia F Durocher, Valérie E Paquet, Steve J Charette
The amoeba Dictyostelium discoideum produces and secretes multilamellar bodies (MLBs) mainly composed of amoebal membranes upon digestion of bacteria. After their secretion, the fate of these MLBs remains unknown. The aim of this study was to determine if protozoa can internalize and digest secreted D. discoideum MLBs. Our results showed that MLBs were ingested by naive axenic D. discoideum cells (i. e. cells not exposed to bacteria and consequently not producing MLBs). Only a small fraction of the ingested MLBs were found in cells' post-lysosomes compared to undigestible beads suggesting that naive amoebae digest them...
October 14, 2017: European Journal of Cell Biology
Lev M Tsypin, Aaron P Turkewitz
Identifying co-regulated genes provides a useful approach for defining pathway-specific machinery in an organism. To be efficient, this approach relies on thorough genome annotation, a process much slower than genome sequencing per se. Tetrahymena thermophila, a unicellular eukaryote, has been a useful model organism and has a fully sequenced but sparsely annotated genome. One important resource for studying this organism has been an online transcriptomic database. We have developed an automated approach to gene annotation in the context of transcriptome data in T...
2017: SoftwareX
Cheng-Bin Liu, Guang-Bo Qu, Meng-Xi Cao, Yong Liang, Li-Gang Hu, Jian-Bo Shi, Yong Cai, Gui-Bin Jiang
Inorganic divalent mercury complexes (Hg(2+)) and monomethylmercury complexes (MeHg) are the main mercury species in aquatic systems and their toxicity to aquatic organisms is of great concern. Tetrahymena is a type of unicellular eukaryotic protozoa located at the bottom of food chain that plays a fundamental role in the biomagnification of mercury. In this work, the dynamic accumulation properties, toxicological characteristics and mechanisms of Hg(2+) and MeHg in five Tetrahymena species were evaluated in detail...
October 23, 2017: Aquatic Toxicology
Juxia Qiao, Jing Xu, Tao Bo, Wei Wang
Histone H1 molecules play a key role in establishing and maintaining higher order chromatin structures. They can bind to linker DNA entering and exiting the nucleosome and regulate transcriptional activity. Tetrahymena thermophila has two histone H1, namely, macronuclear histone H1 and micronuclear histone H1 (Mlh1). Mlh1 is specifically localized at micronuclei during growth and starvation stages. Moreover, Mlh1 is localized around micronuclei and forms a specific structure during the conjugation stage. It co-localizes partially with spindle apparatus during micronuclear meiosis...
2017: PloS One
Yoan Martínez-López, Stephen J Barigye, Oscar Martínez-Santiago, Yovani Marrero-Ponce, James Green, Juan A Castillo-Garit
Several descriptors from atom weighted vectors are used in the prediction of aquatic toxicity of set of organic compounds of 392 benzene derivatives to the protozoo ciliate Tetrahymena pyriformis (log(IGC50)(-1)). These descriptors are calculated using the MD-LOVIs software and various Aggregation Operators are examined with the aim comparing their performances in predicting aquatic toxicity. Variability analysis is used to quantify the information content of these molecular descriptors by means of an information theory-based algorithm...
October 13, 2017: Environmental Toxicology and Pharmacology
Huanxin Zhou, Jing Xu, Wei Wang
Metallothioneins (MTs) constitute a superfamily of cysteine-rich proteins that bind heavy-metal ions by metal-thiolate clusters. Five MT genes from Tetrahymena thermophila was subdivided into 7a (MTT1, MTT3, and MTT5) and 7b (MTT2 and MTT4) subfamilies. In the study, MTT5 was knocked out in Tetrahymena. The mutant cells were sensitive to Cd2+ and Pb2+ but poorly sensitive to Cu+ . In the MTT5 knockout cells, the expression levels of MTT1 and MTT3 were significantly up-regulated under Cd2+ and Pb2+ stresses, whereas the expression levels of MTT2 and MTT4 were significantly up-regulated under Cu+ stress relative to those in the wild-type cells...
November 1, 2017: Journal of Cellular Biochemistry
Yuanyuan Wang, Xiao Chen, Yalan Sheng, Yifan Liu, Shan Gao
DNA N6-methyladenine (6mA) is newly rediscovered as a potential epigenetic mark across a more diverse range of eukaryotes than previously realized. As a unicellular model organism, Tetrahymena thermophila is among the first eukaryotes reported to contain 6mA modification. However, lack of comprehensive information about 6mA distribution hinders further investigations into its function and regulatory mechanism. In this study, we provide the first genome-wide, base pair-resolution map of 6mA in Tetrahymena by applying single-molecule real-time (SMRT) sequencing...
November 16, 2017: Nucleic Acids Research
J A Castillo-Garit, G M Casañola-Martin, S J Barigye, H Pham-The, F Torrens, A Torreblanca
The phenols are structurally heterogeneous pollutants and they present a variety of modes of toxic action (MOA), including polar narcotics, weak acid respiratory uncouplers, pro-electrophiles, and soft electrophiles. Because it is often difficult to determine correctly the mechanism of action of a compound, quantitative structure-activity relationship (QSAR) methods, which have proved their interest in toxicity prediction, can be used. In this work, several QSAR models for the prediction of MOA of 221 phenols to the ciliated protozoan Tetrahymena pyriformis, using Chemistry Development Kit descriptors, are reported...
September 2017: SAR and QSAR in Environmental Research
Tomoko Noto, Kazufumi Mochizuki
Programmed genome rearrangements in ciliates provide fascinating examples of flexible epigenetic genome regulations and important insights into the interaction between transposable elements (TEs) and host genomes. DNA elimination in Tetrahymena thermophila removes approximately 12 000 internal eliminated sequences (IESs), which correspond to one-third of the genome, when the somatic macronucleus (MAC) differentiates from the germline micronucleus (MIC). More than half of the IESs, many of which show high similarity to TEs, are targeted for elimination in cis by the small RNA-mediated genome comparison of the MIC to the MAC...
October 2017: Open Biology
E A Fronhofer, S Gut, F Altermatt
Range expansions and biological invasions are prime examples of transient processes that are likely impacted by rapid evolutionary changes. As a spatial process, range expansions are driven by dispersal and movement behaviour. Although it is widely accepted that dispersal and movement may be context-dependent, for instance density-dependent, and best represented by reaction norms, the evolution of density-dependent movement during range expansions has received little experimental attention. We therefore tested current theory predicting the evolution of increased movement at low densities at range margins using highly replicated and controlled range expansion experiments across multiple genotypes of the protist model system Tetrahymena thermophila...
October 4, 2017: Journal of Evolutionary Biology
Yinka Somorin, Guillaume Bouchard, Joseph Gallagher, Florence Abram, Fiona Brennan, Conor O'Byrne
The soil is a complex ecosystem where interactions between biotic and abiotic factors determine the survival and fate of microbial inhabitants of the system. Having previously shown that Escherichia coli requires the general stress response regulator, RpoS, to survive long term in soil, it was important to determine what specific conditions in this environment necessitate a functional RpoS. This study investigated the susceptibility of soil-persistent E. coli to predation by the single-celled eukaryotes Acanthamoeba polyphaga and Tetrahymena pyriformis, and the role RpoS plays in resisting this predation...
October 16, 2017: FEMS Microbiology Letters
Anoop Narayana Pillai, Sushmita Shukla, Abdur Rahaman
Phosphatidic acid phosphatases are involved in the biosynthesis of phospholipids and triacylglycerol, and also act as transcriptional regulators. Studies to ascertain their role in lipid metabolism and membrane biogenesis are restricted to Opisthokonta and Archaeplastida. Here, we report the role of phosphatidate phosphatase (PAH) in Tetrahymena thermophila, belonging to the Alveolata clade. We identified two PAH homologs in Tetrahymena, TtPAH1 and TtPAH2 Loss of function of TtPAH1 results in reduced lipid droplet number and an increase in endoplasmic reticulum (ER) content...
November 15, 2017: Biology Open
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