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Sample records for tetrahymena

  1. Tetrahymena in the classroom.

    Science.gov (United States)

    Smith, Joshua J; Wiley, Emily A; Cassidy-Hanley, Donna M

    2012-01-01

    Tetrahymena has been a useful model in basic research in part due to the fact it is easy to grow in culture and exhibits a range of complex processes, all within a single cell. For these same reasons Tetrahymena has shown enormous potential as a teaching tool for fundamental principles of biology at multiple science education levels that can be integrated into K-12 classrooms and undergraduate and graduate college laboratory courses. These Tetrahymena-based teaching modules are inquiry-based experiences that are also effective at teaching scientific concepts, retaining students in science, and exciting students about the scientific process. Two learning communities have been developed that utilize Tetrahymena-based teaching modules. Advancing Secondary Science Education with Tetrahymena (ASSET) and the Ciliate Genomics Consortium (CGC) have developed modules for K-12 students and college-level curriculums, respectively. These modules range from addressing topics in ecology, taxonomy, and environmental toxicity to more advanced concepts in biochemistry, proteomics, bioinformatics, cell biology, and molecular biology. An overview of the current modules and their learning outcomes are discussed, as are assessment, dissemination, and sustainability strategies for K-12 and college-level curriculum. Copyright © 2012 Elsevier Inc. All rights reserved.

  2. LYSOSOMAL PHYSIOLOGY IN TETRAHYMENA

    Science.gov (United States)

    Rothstein, Thomas L.; Blum, J. J.

    1974-01-01

    The ingestion of 14C-labeled 9,10-dimethyl-1,2-benzanthracene particles, the extracellular release of acid phosphatase, ribonuclease, and α-glucosidase, and the egestion of preingested dimethylbenzanthracene particles by Tetrahymena taken from logarithmically growing cultures and resuspended in a dilute salt solution were followed in the presence of several pharmacologic agents. Serotonin, caffeine, and, to a lesser extent, dibutyryl cyclic AMP increased the rate of particle ingestion, but did not alter the rate of release of the three acid hydrolases studied. Added catecholamines did not affect either particle ingestion or acid hydrolase release, but particle ingestion was inhibited by the catecholamine antagonists, dichloroisoproterenol, desmethylimipramine, reserpine, and phenoxybenzamine. These drugs also increased the release of acid phosphatase and ribonuclease in 5-h incubations. Desmethylimipramine acted within 1 h to increase acid hydrolase release, but the effect of dichloroisoproterenol developed more slowly and was secondary to a change in cellular content of the hydrolases. Desmethylimipramine increased the energy of activation for the release of acid phosphatase, while dichloroisoproterenol did not. Both of these drugs enhanced the egestion of preingested dimethylbenzanthracene particles, supporting the view that acid hydrolase release occurs through a cytoproct egestion mechanism. Particle ingestion was also inhibited by colchicine, vinblastine, and cytochalasin B, but these agents had no effect on acid hydrolase release, thus further differentiating the properties of the ingestion mechanism from those of the egestion mechanism. It appears that both microtubules and microfilaments play a role in the ingestion process and that this process may be controlled in part by a cyclic AMP-mediated serotoninergic and adrenergic system. PMID:4152946

  3. Metabolism of extracellular phospholipids in Tetrahymena pyriformis

    National Research Council Canada - National Science Library

    Arai, H; Nishikawa, K; Inoue, K; Nozawa, Y; Nojima, S

    1987-01-01

    ...: Cytochalasin B, an inhibitor of endocytosis, suppressed the metabolism almost completely. Phospholipid vesicles were incorporated into a phagosome-like structure in Tetrahymena cells, as observed under an electron microscope...

  4. Metabolism of extracellular phospholipids in Tetrahymena pyriformis.

    Science.gov (United States)

    Arai, H; Nishikawa, K; Inoue, K; Nozawa, Y; Nojima, S

    1987-05-01

    We studied the metabolism of phospholipids exogenously added to cultures of the protozoan, Tetrahymena pyriformis. Tetrahymena cells were found to metabolize the extracellular phospholipids and the fatty acyl chains of the latter were accumulated predominantly as a form of triacylglycerol in the cells. This metabolism was considered to be initiated via endocytosis of phospholipid vesicles, as judged from the following facts: Cytochalasin B, an inhibitor of endocytosis, suppressed the metabolism almost completely. Phospholipid vesicles were incorporated into a phagosome-like structure in Tetrahymena cells, as observed under an electron microscope. When phospholipids doubly labeled with 14C and 3H at the glycerol moiety and fatty acyl chain, respectively, were incubated with Tetrahymena cells, the glycerol moiety and fatty acyl chain at the sn-2-position of the exogenous phospholipids were incorporated into the cellular triacylglycerol fraction in a 1 to 1 ratio. Monoacylglycerol acyltransferase activity was detected in the microsomal fraction of Tetrahymena cells. From these results, together with those of our previous study on lysosomal phospholipid hydrolysis in Tetrahymena (J. Biochem. 99, 125-133 (1986)), it is suggested that the extracellular phospholipids which were taken up by the cells via endocytosis were hydrolyzed through the action of lysosomal phospholipases A1 and C, and also that one of the products, sn-2-monoacylglycerol, served as an acyl acceptor for the synthesis of triacylglycerol via the microsomal "monoacylglycerol pathway."

  5. Modules for C-terminal epitope tagging of Tetrahymena genes

    OpenAIRE

    Kataoka, Kensuke; Schoeberl, Ursula E.; Mochizuki, Kazufumi

    2010-01-01

    Although epitope tagging has been widely used for analyzing protein function in many organisms, there are few genetic tools for epitope tagging in Tetrahymena. In this study, we describe several C-terminal epitope tagging modules that can be used to express tagged proteins in Tetrahymena cells by both plasmid- and PCR-based strategies.

  6. Modules for C-terminal epitope tagging of Tetrahymena genes.

    Science.gov (United States)

    Kataoka, Kensuke; Schoeberl, Ursula E; Mochizuki, Kazufumi

    2010-09-01

    Although epitope tagging has been widely used for analyzing protein function in many organisms, there are few genetic tools for epitope tagging in Tetrahymena. In this study, we describe several C-terminal epitope tagging modules that can be used to express tagged proteins in Tetrahymena cells by both plasmid- and PCR-based strategies. (c) 2010 Elsevier B.V. All rights reserved.

  7. Citrate synthase purified from Tetrahymena mitochondria is identical with Tetrahymena 14-nm filament protein.

    Science.gov (United States)

    Kojima, H; Chiba, J; Watanabe, Y; Numata, O

    1995-07-01

    A 14-nm filament protein (designated as 49K protein) was purified from a ciliated protozoan, Tetrahymena, using the polymerization and depolymerization procedure. Previous studies in our laboratory showed that its primary structure shared a high sequence identity with citrate synthases known so far and that the 49K protein possessed citrate synthase activity. To ascertain whether or not Tetrahymena's mitochondrial citrate synthase is identical to the 49K protein, citrate synthase was purified from Tetrahymena mitochondria using ammonium sulfate fractionation, Butyl-Toyopearl and SP-Toyopearl column chromatographies, based on monitoring of the enzymatic activity. The molecular weight of the purified citrate synthase was estimated to be 49 kDa, as was that of the 49K protein and the enzyme cross-reacted with an anti-49K protein antiserum. The purified citrate synthase showed much the same optimum pH, optimum KCl concentration, effects of substrate concentrations (acetyl-CoA and oxaloacetate), and inhibitory effect by ATP as those of purified 49K protein. Furthermore, an anti-49K protein monoclonal antibody strongly suppressed the enzymatic activity of the purified citrate synthase. Thus, we suggest that mitochondrial citrate synthase and the 49K protein are identical and that the 49K protein has dual functions in the cytoskeleton in cytoplasm and as a TCA cycle enzyme, citrate synthase, in mitochondria.

  8. Biochemical and molecular characterisation of Tetrahymena thermophila extracellular cysteine proteases

    Directory of Open Access Journals (Sweden)

    Tiedtke Arno

    2006-02-01

    Full Text Available Abstract Background Over the last decades molecular biologic techniques have been developed to alter the genome and proteome of Tetrahymena thermophila thereby providing the basis for recombinant protein expression including functional human enzymes. The biotechnological potential of Tetrahymena has been proved in numerous publications, demonstrating fast growth, high biomass, fermentation in ordinary bacterial/yeast equipment, up-scalability, existence of cheap and chemical defined media. For these reasons Tetrahymena offers promising opportunities for the development of a high expression system. Yet optimised high yield strains with protease deficiency such as commonly used in yeast and bacterial systems are not available. Results This work presents the molecular identification of predominant proteases secreted into the medium by Tetrahymena thermophila. A one-step purification of the proteolytic enzymes is described. Conclusion The information provided will allow silencing of protease activity by either knock out methods or by Tetrahymena specific antisense-ribosome-techniques. This will facilitate the next step in the advancement of this exciting organism for recombinant protein production.

  9. Targeting of liposomes containing methotrexate towards Tetrahymena pyriformis cells.

    Science.gov (United States)

    Kotsifaki, H; Kapoulas, V; Deliconstantinos, G

    1985-01-01

    The uptake of liposomes containing methotrexate by Tetrahymena pyriformis cells was investigated with the aim of producing liposome-cell association enabling methotrexate to be introduced into the cytoplasm of intact cells. Incubation of liposomes containing methotrexate with tetrahymena pyriformis cells resulted in a time and concentration-dependent uptake of entrapped methotrexate by the cells. The uptake by Tetrahymena pyriformis cells (at 1 hr) of liposomes prepared by phospholipids and gangliosides extracted from Tetrahymena pyriformis cells was approximately three fold higher than that of liposomes prepared by commercial phospholipids. Approximately 90% of liposome uptake could be inhibited by cytochalasin B and also by NaN3 and 2-deoxyglucose. This was consistent with the uptake being the result of endocytosis. The remaining uptake was probably the result of adhesion of liposomes to the cell membrane. The rate of efflux vs time of methotrexate entrapped in liposomes was much slower than that of free methotrexate which reinforces the concept that endocytosis is the main mode of liposomes uptake by the cells. Liposomes containing methotrexate at concentrations as low as 4.5 microM effectively inhibited the activity of dihydrofolate reductase which was used as a function parameter in this study. Similar inhibition of the enzyme activity by free methotrexate was achieved only at concentrations as high as 880 microM. The influence of liposomes lipid composition on the targeting of liposomes to Tetrahymena pyriformis cells was discussed.

  10. Induction of anti-actin drug resistance in Tetrahymena.

    Science.gov (United States)

    Zackroff, Robert V; Hufnagel, Linda A

    2002-01-01

    Both cytochalasin D and latrunculin B reversibly inhibited Tetrahymena phagocytosis at concentrations similar to those effective in mammalian systems, even though ciliate actins are known to be highly divergent from mammalian actins. Overnight exposure to relatively low (0.25 microM) concentrations of latrunculin B induced resistance in Tetrahymena to the inhibitory effects of that drug, as well as cross-resistance to cytochalasin D. However, much higher (> 30 microM) concentrations of cytochalasin D were required for induction of cross-resistance to latrunculin B. Anti-actin drug resistance in Tetrahymena may involve a general multidrug resistance mechanism and/or specific feedback regulation of F-actin assembly and stability.

  11. Small phosphatidate phosphatase (TtPAH2) of Tetrahymena ...

    Indian Academy of Sciences (India)

    Phosphatidate phosphatases (PAH) play a central role in lipid metabolism and intracellular signaling. Herein, we report thepresence of a low-molecular-weight PAH homolog in the single-celled ciliate Tetrahymena thermophila. In vitro phosphataseassay showed that TtPAH2 belongs to the magnesium-dependent ...

  12. Tetrahymena dynamin-related protein 6 self-assembles ...

    Indian Academy of Sciences (India)

    Usha P Kar

    2017-12-30

    Dec 30, 2017 ... Self-assembly on target membranes is one of the important properties of all dynamin family proteins. Drp6, a dynamin- related protein in Tetrahymena, controls nuclear remodelling and undergoes cycles of assembly/disassembly on the nuclear envelope. To elucidate the mechanism of Drp6 function, we ...

  13. Inhibition of Tetrahymena pyriformis growth by Aliphatic Alcohols ...

    African Journals Online (AJOL)

    Une étude Relation Quantitative Structure- Activité (QSAR) a été réalisée pour évaluer la toxicité relative d'un mélange composé de 21 alcools (à chaînes linéaires et ramifiées) et 9 amines aliphatiques normales, en terme de concentration d'inhibition 50% de la croissance (IGC50) de Tetrahymena pyriformis . L'approche ...

  14. Comparative Proteome Bioinformatics: Identification of Phosphotyrosine Signaling Proteins in the Unicellular Protozoan Ciliate Tetrahymena

    DEFF Research Database (Denmark)

    Gammeltoft, Steen; Christensen, Søren Tvorup; Joachimiak, Marcin

    2005-01-01

    Tetrahymena, bioinformatics, cilia, evolution, signaling, TtPTK1, PTK, Grb2, SH-PTP 2, Plcy, Src, PTP, PI3K, SH2, SH3, PH......Tetrahymena, bioinformatics, cilia, evolution, signaling, TtPTK1, PTK, Grb2, SH-PTP 2, Plcy, Src, PTP, PI3K, SH2, SH3, PH...

  15. Comparative study of infection with Tetrahymena of different ornamental fish species.

    Science.gov (United States)

    Sharon, G; Pimenta Leibowitz, M; Chettri, J Kumar; Isakov, N; Zilberg, D

    2014-01-01

    Tetrahymena is a ciliated protozoan that can infect a wide range of fish species, although it is most commonly reported in guppies (Poecilia reticulata). The aim of this study was to compare the susceptibility to infection with Tetrahymena of five different ornamental fish species from two different super orders. The species examined were platy (Xiphophorus), molly (Poecilia sphenops) and angelfish (Pterophyllum scalare) of the Acanthopterygii super order (which also includes guppies) and goldfish (Carassius auratus auratus) and koi carp (Cyprinus carpio) of the Ostariophysi super order. These two super orders are phylogenetically distant from each other. Infection with Tetrahymena resulted in parasite invasion of internal organs, skin and muscle in all fish species. A relatively strong inflammatory response was observed in infected goldfish and koi, with negligible response in fish species of the Acanthopterygii super order. Guppies were the most susceptible to Tetrahymena infection, exhibiting a mortality rate of 87% and 100% in two separate experiments. A high mortality rate was also observed in platy (77%), while that of molly and angelfish was significantly lower (23% and 33%, respectively). Goldfish and koi carp were less susceptible to infection compared with guppies (24% and 59% mortality, respectively). Immunization studies revealed that the Tetrahymena are immunogenic, since infection of koi carp increased their Tetrahymena immobilization response by approximately three-fold at 3 weeks post infection, while immunization with Tetrahymena plus adjuvant increased their immobilization response by approximately 30-fold. Copyright © 2013 Elsevier Ltd. All rights reserved.

  16. Protective immunization against Tetrahymena sp. infection in guppies (Poecilia reticulata).

    Science.gov (United States)

    Chettri, J Kumar; Leibowitz, M Pimenta; Ofir, R; Zilberg, D

    2009-08-01

    Systemic tetrahymenosis constitutes a serious problem in guppy (Poecilia reticulata) production worldwide and no therapeutic solution is available for this disease. Three immunization trials were conducted, testing the effectiveness of different Tetrahymena preparations applied by intraperitoneal injection (IP) with or without Freund's complete adjuvant (FCA) and with or without booster dose. In trial 1, immunization with the pathogenic Tet-NI 6 lysate and live attenuated Tet-NI 1 did not provide significant protection from infection, although infection rates were significantly lower in the Tet-NI 6-immunized group than in controls. In trial 2, mortality in Tet-NI 6 + FCA-immunized fish was 10%, significantly lower than in all other treatment groups, including Tet-NI 6 lysate, live attenuated Tet-NI 1 and controls (77, 67 and 73%, respectively). In trial 3, the lowest mortality rates were obtained in the Tet-NI 6 + FCA + booster-immunized group (15%). These levels were lower but not significantly different from the non-boostered Tet-NI 6-immunized group (28%) and the groups immunized with Tet-NI 1, with and without booster (32 and 34%, respectively). Mortality in these four groups was significantly lower than in controls, including adjuvant- and PBS-injected groups (72 and 81%, respectively). Body homogenates of immunized fish immobilized Tetrahymena in-vitro, as compared to no or very little immobilization in controls. Lysozyme levels in the Tet-NI 6 + FCA + booster group were significantly higher than in all other treatments in trial 2 and controls in trial 3. There was no significant difference in anti-protease activity among the differently immunized fish. We conclude that immunization with Tetrahymena lysates in FCA confers a high degree of protection from infection, suggesting this preparation as a basis for vaccine development.

  17. Radiation-induced inhibition of RNA synthesis in Tetrahymena pyriformis.

    Science.gov (United States)

    Ernst, S G; Rustad, R C; Oleinick, N L

    1975-07-01

    Radiation-induced disturbances in RNA synthesis were investigated in exponentially growing Tetrahymena. Sub-lethal doses of gamma-radiation lead to a transient, dose-dependent decrease in the rate of total RNA synthesis measured by 3H-uridine incorporation, without an alteration of 3H-uridine uptake by the cells. The rate of 3H-uridine incorporation decreases exponentially with dose. In contrast, the duration of inhibition of RNA synthesis is linearly dependent on dose. Target-theory calculations suggest that the sensitive molecule has a molecular weight of about 2 X 10(7) Daltons.

  18. Experimental identification and analysis of macronuclear non-coding RNAs from the ciliate Tetrahymena thermophila

    DEFF Research Database (Denmark)

    Andersen, Kasper Langebjerg; Nielsen, Henrik

    2012-01-01

    The ciliate Tetrahymena thermophila is an important eukaryotic model organism that has been used in pioneering studies of general phenomena, such as ribozymes, telomeres, chromatin structure and genome reorganization. Recent work has shown that Tetrahymena has many classes of small RNA molecules...... class was small nucleolar RNAs (snoRNAs), many of which are formed by an unusual maturation pathway. The modifications guided by the snoRNAs were analyzed bioinformatically and experimentally and many Tetrahymena-specific modifications were found, including several in an essential, but not conserved...

  19. Isolation and characterization of the actin gene from Tetrahymena thermophila

    Science.gov (United States)

    Cupples, Claire G.; Pearlman, Ronald E.

    1986-01-01

    The macronucleus of Tetrahymena thermophila contains a single actin gene. We have isolated this gene from a partial plasmid library by using the yeast actin gene as a probe. The nucleotide sequence of the gene has been determined and the amino acid sequence of the potential protein deduced. The encoded protein is 375 amino acids long, one amino acid longer than the yeast actin. It is one of the most divergent actins sequenced to date, being only 75% homologous to yeast actin. Unlike the actin genes from most other organisms, it does not contain introns. The coding region contains TAA and TAG codons; the translation termination codon is TGA. Comparison of the amino acid sequence of the Tetrahymena actin with that of actins from other organisms suggests that TAG may code for glutamic acid. The gene is transcribed from multiple initiation sites between 57 and 98 nucleotides upstream of the translation start codon. The 5′ flanking region is very A+T-rich and contains numerous “TATA-like” sequences upstream of the transcription start sites. Images PMID:16593729

  20. Netrin-1 Peptide Is a Chemorepellent in Tetrahymena thermophila

    Directory of Open Access Journals (Sweden)

    Heather Kuruvilla

    2016-01-01

    Full Text Available Netrin-1 is a highly conserved, pleiotropic signaling molecule that can serve as a neuronal chemorepellent during vertebrate development. In vertebrates, chemorepellent signaling is mediated through the tyrosine kinase, src-1, and the tyrosine phosphatase, shp-2. Tetrahymena thermophila has been used as a model system for chemorepellent signaling because its avoidance response is easily characterized under a light microscope. Our experiments showed that netrin-1 peptide is a chemorepellent in T. thermophila at micromolar concentrations. T. thermophila adapts to netrin-1 over a time course of about 10 minutes. Netrin-adapted cells still avoid GTP, PACAP-38, and nociceptin, suggesting that netrin does not use the same signaling machinery as any of these other repellents. Avoidance of netrin-1 peptide was effectively eliminated by the addition of the tyrosine kinase inhibitor, genistein, to the assay buffer; however, immunostaining using an anti-phosphotyrosine antibody showed similar fluorescence levels in control and netrin-1 exposed cells, suggesting that tyrosine phosphorylation is not required for signaling to occur. In addition, ELISA indicates that a netrin-like peptide is present in both whole cell extract and secreted protein obtained from Tetrahymena thermophila. Further study will be required in order to fully elucidate the signaling mechanism of netrin-1 peptide in this organism.

  1. Establishment of a Cre/loxP recombination system for N-terminal epitope tagging of genes in Tetrahymena.

    Science.gov (United States)

    Busch, Clara Jana-Lui; Vogt, Alexander; Mochizuki, Kazufumi

    2010-07-13

    Epitope tagging is a powerful strategy to study the function of proteins. Although tools for C-terminal protein tagging in the ciliated protozoan Tetrahymena thermophila have been developed, N-terminal protein tagging in this organism is still technically demanding. In this study, we have established a Cre/loxP recombination system in Tetrahymena and have applied this system for the N-terminal epitope tagging of Tetrahymena genes. Cre can be expressed in Tetrahymena and localizes to the macronucleus where it induces precise recombination at two loxP sequences in direct orientation in the Tetrahymena macronuclear chromosome. This Cre/loxP recombination can be used to remove a loxP-flanked drug-resistance marker from an N-terminal tagging construct after it is integrated into the macronucleus. The system established in this study allows us to express an N-terminal epitope tagged gene from its own endogenous promoter in Tetrahymena.

  2. Establishment of a Cre/loxP recombination system for N-terminal epitope tagging of genes in Tetrahymena

    OpenAIRE

    Mochizuki Kazufumi; Vogt Alexander; Busch Clara

    2010-01-01

    Abstract Background Epitope tagging is a powerful strategy to study the function of proteins. Although tools for C-terminal protein tagging in the ciliated protozoan Tetrahymena thermophila have been developed, N-terminal protein tagging in this organism is still technically demanding. Results In this study, we have established a Cre/loxP recombination system in Tetrahymena and have applied this system for the N-terminal epitope tagging of Tetrahymena genes. Cre can be expressed in Tetrahymen...

  3. pH-dependent effects of 2,4-dinitrophenol (DNP) on proliferation, endocytosis, fine structure and DNP resistance in Tetrahymena

    DEFF Research Database (Denmark)

    Nilsson, Jytte R.

    1995-01-01

    Biologi, 2,4-dinitrophenol, pH-dependence, fine structure, cell proliferation, phagocytosis, Tetrahymena pyriformis......Biologi, 2,4-dinitrophenol, pH-dependence, fine structure, cell proliferation, phagocytosis, Tetrahymena pyriformis...

  4. Comparative study of infection with Tetrahymena of different ornamental fish species

    DEFF Research Database (Denmark)

    Sharon, G.; Leibowitz, M. Pimenta; Chettri, Jiwan Kumar

    2014-01-01

    Tetrahymena is a ciliated protozoan that can infect a wide range of fish species, although it is most commonly reported in guppies (Poecilia reticulata). The aim of this study was to compare the susceptibility to infection with Tetrahymena of five different ornamental fish species from two...... different super orders. The species examined were platy (Xiphophorus), molly (Poecilia sphenops) and angelfish (Pterophyllum scalare) of the Acanthopterygii super order (which also includes guppies) and goldfish (Carassius auratus auratus) and koi carp (Cyprinus carpio) of the Ostariophysi super order...... of the Acanthopterygii super order. Guppies were the most susceptible to Tetrahymena infection, exhibiting a mortality rate of 87% and 100% in two separate experiments. A high mortality rate was also observed in platy (77%), while that of molly and angelfish was significantly lower (23% and 33%, respectively). Goldfish...

  5. Environmental and physiological conditions affecting Tetrahymena sp. infection in guppies, Poecilia reticulata Peters.

    Science.gov (United States)

    Pimenta Leibowitz, M; Ariav, R; Zilberg, D

    2005-09-01

    Parasitic infections caused by Tetrahymena sp. constitute a serious problem in guppies, Poecilia reticulata. Tetrahymena was isolated from skin lesions of naturally infected guppies in a commercial aquaculture farm, cultured in vitro and used in subsequent experimental infections. In addition to guppies, angelfish, Pterophyllum scalare, platyfish, Xiphophorus maculates, and neontetra, Paracheirodon innesi, were susceptible, whereas tilapia (Oreochromis niloticus xO. aureus) was resistant. The ciliate had a high affinity for dead fish. Skin abrasion did not affect the infection, but fish with gas bubble disease exhibited a significantly higher infection than non-affected fish. Infection was significantly higher when fish were exposed to high levels of ammonia, high organic load and low water temperatures. Under shipment conditions, infection was significantly elevated. Full recovery was achieved at a low fish density. Results suggest that poor environmental and physiological conditions enhance infection with Tetrahymena sp.

  6. Updating rDNA restriction enzyme maps of Tetrahymena reveals four new intron-containing species

    DEFF Research Database (Denmark)

    Nielsen, Henrik; Simon, E M; Engberg, J

    1985-01-01

    The extrachromosomal rDNA molecules from a number of Tetrahymena strains were characterized by restriction enzyme mapping using three different restriction enzymes combined with gel blotting and hybridization analysis. Strains from four out of six recently described species were found to contain...

  7. Role of apoptosis-inducing factor (AIF in programmed nuclear death during conjugation in Tetrahymena thermophila

    Directory of Open Access Journals (Sweden)

    Endoh Hiroshi

    2010-02-01

    Full Text Available Abstract Background Programmed nuclear death (PND, which is also referred to as nuclear apoptosis, is a remarkable process that occurs in ciliates during sexual reproduction (conjugation. In Tetrahymena thermophila, when the new macronucleus differentiates, the parental macronucleus is selectively eliminated from the cytoplasm of the progeny, concomitant with apoptotic nuclear events. However, the molecular mechanisms underlying these events are not well understood. The parental macronucleus is engulfed by a large autophagosome, which contains numerous mitochondria that have lost their membrane potential. In animals, mitochondrial depolarization precedes apoptotic cell death, which involves DNA fragmentation and subsequent nuclear degradation. Results We focused on the role of mitochondrial apoptosis-inducing factor (AIF during PND in Tetrahymena. The disruption of AIF delays the normal progression of PND, specifically, nuclear condensation and kilobase-size DNA fragmentation. AIF is localized in Tetrahymena mitochondria and is released into the macronucleus prior to nuclear condensation. In addition, AIF associates and co-operates with the mitochondrial DNase to facilitate the degradation of kilobase-size DNA, which is followed by oligonucleosome-size DNA laddering. Conclusions Our results suggest that Tetrahymena AIF plays an important role in the degradation of DNA at an early stage of PND, which supports the notion that the mitochondrion-initiated apoptotic DNA degradation pathway is widely conserved among eukaryotes.

  8. Poliovirus and echovirus survival in Tetrahymena pyriformis culture in vivo.

    Science.gov (United States)

    Danes, L; Cerva, L

    1984-01-01

    Axenic cultures of Tetrahymena pyriformis, strain I MT IV, grown in a defined medium at room temperature, were used to study interactions of these protozoa with vaccination strain L Sc 2ab of poliovirus type 1, vaccination strain P 712 of poliovirus type 2 and with type 30 echovirus, strain 480/78. T. pyriformis cultures in media containing 10(3.0) TCD50/1 ml of type poliovirus, 10(3.0) TCD50/1 ml of type 2 poliovirus or 10(2.5) TCD50/1 ml echovirus 30 and in virus-free medium did not differ one from another in their growth and die-away kinetics during the 21 days of observation. Two-day T. pyriformis cultures were infected with poliovirus 1 (initial concentration 10(3.2) TCD50/1 ml), and poliovirus 2 and echovirus 30 (initial concentrations 10(3.0) TCD50/1 ml). Viruses were titrated in test tube cultures of BGM cells. The supernatant fluid, standardized sediment and samples of control virus suspension free of protozoa were titrated after 0, 2, 6, 10, 13, 18, 28 and 30 days. Most of the virus in culture was found associated with the sediment, both in the period of active growth and during the die-away phase of T. pyriformis protozoa. The virus in sediment was present at higher titres and its survival time was longer than in virus in liquid phase. Thirteen days after the first contact between T. pyriformis and virus the sediment and supernatant fluid of the old protozoan culture and the T. pyriformis-free control viral suspension were taken and used as inocula for new two-day T. pyriformis cultures.(ABSTRACT TRUNCATED AT 250 WORDS)

  9. Establishment of a Cre/loxP recombination system for N-terminal epitope tagging of genes in Tetrahymena

    Directory of Open Access Journals (Sweden)

    Mochizuki Kazufumi

    2010-07-01

    Full Text Available Abstract Background Epitope tagging is a powerful strategy to study the function of proteins. Although tools for C-terminal protein tagging in the ciliated protozoan Tetrahymena thermophila have been developed, N-terminal protein tagging in this organism is still technically demanding. Results In this study, we have established a Cre/loxP recombination system in Tetrahymena and have applied this system for the N-terminal epitope tagging of Tetrahymena genes. Cre can be expressed in Tetrahymena and localizes to the macronucleus where it induces precise recombination at two loxP sequences in direct orientation in the Tetrahymena macronuclear chromosome. This Cre/loxP recombination can be used to remove a loxP-flanked drug-resistance marker from an N-terminal tagging construct after it is integrated into the macronucleus. Conclusions The system established in this study allows us to express an N-terminal epitope tagged gene from its own endogenous promoter in Tetrahymena.

  10. Effect of Cerophyl growth medium on exocytosis in Tetrahymena thermophila.

    Science.gov (United States)

    Pesciotta, D M; Satir, B H

    1985-10-01

    Culturing the ciliate Tetrahymena thermophila in Cerophyl has provided an opportunity for studying the assembly and/or synthesis of the intramembrane particle array, the rosette, which marks the site of exocytosis in these cells. Cultures grown in this medium cease cell division after only 12h and enter 'stationary phase' earlier (12h of growth) relative to growth in standard medium (proteose peptone). In addition, the cell changes from the normally observed pear-shaped body to a thinner more ellipsoid form. Despite the initial similarities to starving cells, several differences are observed in the Cerophyl-grown cells. One is that cell size remains constant for at least 72h in contrast to starved cells. Secondly, in spite of this block in cell division, results from freeze-fracture replicas of the cell membrane of these cells show that they continue to assemble rosettes, the number of which increases approximately six times, from 0.34 rosette/microgram2 to 2.1 rosettes/microgram2. Addition of the protein synthesis inhibitor, cycloheximide (6h exposure), during growth in Cerophyl shows that 70% of rosettes can be assembled, despite the blockage of translation, by using pre-existing component(s) from a pool. The remaining 30% must involve de novo synthesis of one or more components; this percentage can be increased with longer exposure to the drug. Thirdly, an apparent increase in the number of mucocysts is observed by thin-section electron microscopy. At first (12-24h) only docked mucocysts seem to accumulate in the cell. However, by 36h a considerable increase seems to have taken place, particularly in the number of mucocysts located in the cytoplasm. In the cycloheximide-treated cells this increase in mucocysts begins to be blocked after 6h of exposure to the drug. These observations are in agreement with the results obtained from the freeze-fracture data on the concomitant increase in number of rosettes. This system therefore offers the first possibility of

  11. Involvement of a putative intercellular signal-recognizing G protein-coupled receptor in the engulfment of Salmonella by the protozoan Tetrahymena

    Directory of Open Access Journals (Sweden)

    P.N. Agbedanu

    2013-07-01

    Full Text Available In an effort to investigate the molecular basis of protozoa engulfment-mediated hypervirulence of Salmonella in cattle, we evaluated protozoan G protein-coupled receptors (GPCRs as transducers of Salmonella engulfment by the model protozoan Tetrahymena. Our laboratory previously demonstrated that non-pathogenic protozoa (including Tetrahymena engulf Salmonella and then exacerbate its virulence in cattle, but the mechanistic details of the phenomenon are not fully understood. GPCRs were investigated since these receptors facilitate phagocytosis of particulates by Tetrahymena, and a GPCR apparently modulates bacterial engulfment for the pathogenic protozoan Entamoeba histolytica. A database search identified three putative Tetrahymena GPCRs, based on sequence homologies and predicted transmembrane domains, that were the focus of this study. Salmonella engulfment by Tetrahymena was assessed in the presence of suramin, a non-specific GPCR inhibitor. Salmonella engulfment was also assessed in Tetrahymena in which expression of putative GPCRs was knocked-down using RNAi. A candidate GPCR was then expressed in a heterologous yeast expression system for further characterization. Our results revealed that Tetrahymena were less efficient at engulfing Salmonella in the presence of suramin. Engulfment was reduced concordantly with a reduction in the density of protozoa. RNAi-based studies revealed that knock-down of one the Tetrahymena GPCRs caused diminished engulfment of Salmonella. Tetrahymena lysates activated this receptor in the heterologous expression system. These data demonstrate that the Tetrahymena receptor is a putative GPCR that facilitates bacterial engulfment by Tetrahymena. Activation of the putative GPCR seemed to be related to protozoan cell density, suggesting that its cognate ligand is an intercellular signaling molecule.

  12. QSAR studies for the acute toxicity of nitrobenzenes to the Tetrahymena pyriformis

    Directory of Open Access Journals (Sweden)

    Wang Dan-Dan

    2014-01-01

    Full Text Available Quantitative structure-activity relationship (QSAR models play a key role in finding the relationship between molecular structures and the toxicity of nitrobenzenes to Tetrahymena pyriformis. In this work, genetic algorithm, along with partial least square (GA-PLS was employed to select optimal subset of descriptors that have significant contribution to the toxicity of nitrobenzenes to Tetrahymena pyriformis. A set of five descriptors, namely G2, HOMT, G(Cl…Cl, Mor03v and MAXDP, was used for the prediction of the toxicity of 45 nitrobenzene derivatives and then were used to build the model by multiple linear regression (MLR method. It turned out that the built model, whose stability was confirmed using the leave-one-out validation and external validation test, showed high statistical significance (R2=0.963, Q2LOO=0.944. Moreover, Y-scrambling test indicated there was no chance correlation in this model.

  13. Modeling the toxicity of chemicals to Tetrahymena pyriformis using molecular fragment descriptors and probabilistic neural networks.

    Science.gov (United States)

    Niculescu, S P; Kaiser, K L; Schultz, T W

    2000-10-01

    The results of an investigation into the use of a probabilistic neural network (PNN)-based methodology to model the 48-h ICG50 (inhibitory concentration for population growth) sublethal toxicity of 825 chemicals to the ciliate Tetrahymena pyriformis are presented. The information fed into the neural networks is solely based on simple molecular descriptors as can be derived from the chemical structure. In contrast to most other toxicological models, the octanol/water partition coefficient is not used as an input parameter, and no rules of thumb or other substance selection criteria are employed. The cross-validation and external validation experiments confirmed excellent recognitive and predictive capabilities of the resulting models and recommend their future use in evaluating the potential of most organic molecules to be toxic to Tetrahymena.

  14. Cysteine proteases and acid phosphatases contribute to Tetrahymena spp. pathogenicity in guppies, Poecilia reticulata.

    Science.gov (United States)

    Leibowitz, M Pimenta; Ofir, R; Golan-Goldhirsh, A; Zilberg, D

    2009-12-03

    Systemic tetrahymenosis caused by the protozoan parasite Tetrahymena spp. is a serious problem in guppy (Poecilia reticulata) farms worldwide. There is no therapeutic solution for the systemic form of this disease. Guppies severely infected with Tetrahymena spp. were imported by a commercial ornamental fish farm and brought to our laboratory. Tetrahymena sp. (Tet-NI) was isolated and in vitro cultured. Isolates maintained in culture for different time periods (as reflected by different numbers of passages in culture) were analyzed-Tet-NI 1, 4, 5 and 6, with Tet-NI 1 being cultured for the longest period (about 15 months, 54 passages) and Tet-NI 6 for the shortest (2.5 months, 10 passages). Controlled internal infection was successfully achieved by IP injection with most isolates, except for Tet-NI 1 which produced no infection. The isolate Tet-NI 6 induced the highest infection rates in internal organs (80% vs. 50% and 64% for Tet-NI 4 and 5, respectively) and mortality rates (67% vs. 20% and 27% for Tet-NI 4 and 5, respectively, and 6.7% for Tet-NI 1). The correlation between pathogenicity and Tetrahymena enzymatic activity was studied. Electrophoretic analyses revealed at least two bands of gelanolytic activity in Tet-NI 4 and 5, three bands in Tet-NI 6, and no activity in Tet-NI 1. Total inhibition of gelanolytic activity was observed after pretreatment of Tet-NI 6 with E-64, a highly selective cysteine protease inhibitor. Using hemoglobin as a substrate, Tet-NI 6 had two bands of proteolytic activity and no bands were observed in Tet-NI 1. A correlation was observed between pathogenicity and acid phosphatase activities (analyzed by commercial fluorescence kit) for Tet-NI 1 and Tet-NI 6.

  15. Use of Tetrahymena thermophila To Study the Role of Protozoa in Inactivation of Viruses in Water▿

    OpenAIRE

    Pinheiro, Marcel D. O.; Power, Mary E.; Butler, Barbara J.; Dayeh, Vivian R.; Slawson, Robin; Lee, Lucy E. J.; Lynn, Denis H.; Bols, Niels C.

    2006-01-01

    The ability of a ciliate to inactivate bacteriophage was studied because these viruses are known to influence the size and diversity of bacterial populations, which affect nutrient cycling in natural waters and effluent quality in sewage treatment, and because ciliates are ubiquitous in aquatic environments, including sewage treatment plants. Tetrahymena thermophila was used as a representative ciliate; T4 was used as a model bacteriophage. The T4 titer was monitored on Escherichia coli B in ...

  16. Use of Tetrahymena thermophila to study the role of protozoa in inactivation of viruses in water.

    Science.gov (United States)

    Pinheiro, Marcel D O; Power, Mary E; Butler, Barbara J; Dayeh, Vivian R; Slawson, Robin; Lee, Lucy E J; Lynn, Denis H; Bols, Niels C

    2007-01-01

    The ability of a ciliate to inactivate bacteriophage was studied because these viruses are known to influence the size and diversity of bacterial populations, which affect nutrient cycling in natural waters and effluent quality in sewage treatment, and because ciliates are ubiquitous in aquatic environments, including sewage treatment plants. Tetrahymena thermophila was used as a representative ciliate; T4 was used as a model bacteriophage. The T4 titer was monitored on Escherichia coli B in a double-agar overlay assay. T4 and the ciliate were incubated together under different conditions and for various times, after which the mixture was centrifuged through a step gradient, producing a top layer free of ciliates. The T4 titer in this layer decreased as coincubation time increased, but no decrease was seen if phage were incubated with formalin-fixed Tetrahymena. The T4 titer associated with the pellet of living ciliates was very low, suggesting that removal of the phage by Tetrahymena inactivated T4. When Tetrahymena cells were incubated with SYBR gold-labeled phage, fluorescence was localized in structures that had the shape and position of food vacuoles. Incubation of the phage and ciliate with cytochalasin B or at 4 degrees C impaired T4 inactivation. These results suggest the active removal of T4 bacteriophage from fluid by macropinocytosis, followed by digestion in food vacuoles. Such ciliate virophagy may be a mechanism occurring in natural waters and sewage treatment, and the methods described here could be used to study the factors influencing inactivation and possibly water quality.

  17. Use of Tetrahymena thermophila To Study the Role of Protozoa in Inactivation of Viruses in Water▿

    Science.gov (United States)

    Pinheiro, Marcel D. O.; Power, Mary E.; Butler, Barbara J.; Dayeh, Vivian R.; Slawson, Robin; Lee, Lucy E. J.; Lynn, Denis H.; Bols, Niels C.

    2007-01-01

    The ability of a ciliate to inactivate bacteriophage was studied because these viruses are known to influence the size and diversity of bacterial populations, which affect nutrient cycling in natural waters and effluent quality in sewage treatment, and because ciliates are ubiquitous in aquatic environments, including sewage treatment plants. Tetrahymena thermophila was used as a representative ciliate; T4 was used as a model bacteriophage. The T4 titer was monitored on Escherichia coli B in a double-agar overlay assay. T4 and the ciliate were incubated together under different conditions and for various times, after which the mixture was centrifuged through a step gradient, producing a top layer free of ciliates. The T4 titer in this layer decreased as coincubation time increased, but no decrease was seen if phage were incubated with formalin-fixed Tetrahymena. The T4 titer associated with the pellet of living ciliates was very low, suggesting that removal of the phage by Tetrahymena inactivated T4. When Tetrahymena cells were incubated with SYBR gold-labeled phage, fluorescence was localized in structures that had the shape and position of food vacuoles. Incubation of the phage and ciliate with cytochalasin B or at 4°C impaired T4 inactivation. These results suggest the active removal of T4 bacteriophage from fluid by macropinocytosis, followed by digestion in food vacuoles. Such ciliate virophagy may be a mechanism occurring in natural waters and sewage treatment, and the methods described here could be used to study the factors influencing inactivation and possibly water quality. PMID:17114327

  18. Expression of a cell surface immobilization antigen during serotype transformation in Tetrahymena thermophila.

    OpenAIRE

    Williams, N. E.; Doerder, F. P.; Ron, A

    1985-01-01

    A temperature shift from 40 to 28 degrees C rapidly induced expression of a specific immobilization antigen at the cell surface in Tetrahymena thermophila. This transformation was inhibited by actinomycin D and cycloheximide but not by colchicine or cytochalasin B. The major surface antigen expressed at 28 degrees C in cells homozygous for the SerH3 allele was partially purified, and an antiserum against this preparation was raised in rabbits. Electrophoresis, immunoblot, and [35S]methionine ...

  19. Treatment development for systemic Tetrahymena sp. infection in guppies, Poecilia reticulata Peters.

    Science.gov (United States)

    Leibowitz, M Pimenta; Chettri, J Kumar; Ofir, R; Zilberg, D

    2010-06-01

    Antibacterial and antiparasitic agents and a cysteine protease inhibitor (E-64) were tested against Tetrahymena infection, a serious problem in guppy production worldwide. Chemicals were tested in vitro by a colorimetric assay for Tetrahymena survival. The most effective were niclosamide, albendazole and chloroquine, with 23%, 35% and 60% survival, respectively, following 2-h exposure to 100 ppm. Longer incubation periods resulted in greater reductions in survival. Niclosamide was further studied in vivo at different dosages, administered orally to Tetrahymena-infected guppies. Mortality rates were significantly lower in all treatment groups; in trial I, 30% and 33% mortality in 5 and 40 mg kg(-1) niclosamide-fed fish vs. 59% mortality in controls; in trial II, 35%, 13% and 10% in 50, 100 and 200 mg kg(-1) niclosamide-fed fish vs. 64% in controls. The effect of the cysteine protease inhibitor E64 was tested in tissue culture, by measuring histolytic activity of the parasite (Tet-NI) on a guppy-fin cell line, based on cell depletion. Tet-NI feeding activity was significantly reduced following pretreatment with E-64 relative to non-treated Tet-NI. E-64-pretreated Tet-NI was injected i.p. into guppies: recorded mortality rates were significantly lower (35%) than that in non-treated Tet-NI (60%), suggesting inhibition of the parasite's cysteine protease as a possible therapeutic approach.

  20. The relationship between energy-dependent phagocytosis and the rate of oxygen consumption in Tetrahymena.

    Science.gov (United States)

    Skriver, L; Nilsson, J R

    1978-12-01

    The induction of high rates of food vacuole formation in Tetrahymena pyriformis increased the rate of respiration in exponentially growing cells by 17% and in starving cells by 47.5%. The increased rate of oxygen uptake was caused by phagocytosis itself, as shown by comparing the rates of respiration of a Tetrahymena mutant exposed to particles at the permissive or restrictive temperatures for food vacuole formation. During cell division, heat-synchronized cells in rich, particle-supplemented medium showed a significant decrease in the rate of respiration. Furthermore, dimethyl sulphoxide, in concentrations sufficient to block food vacuole formation, suppressed the rate of respiration to a level similar to that of starved cells. Cytochalasin B, fowever, did not reduce the rate of oxygen uptake despite the inability of the cells to complete the formation of food vacuoles during treatment; a possible explanation for this finding is discussed. There was a strong correlation between formation of food vacuoles and a high metabolic rate in Tetrahymena.

  1. The effects of nucleoside analogs on telomerase and telomeres in Tetrahymena.

    Science.gov (United States)

    Strahl, C; Blackburn, E H

    1994-03-25

    The ribonucleoprotein enzyme telomerase is a specialized type of cellular reverse transcriptase which synthesizes one strand of telomeric DNA, using as the template a sequence in the RNA moiety of telomerase. We analyzed the effects of various nucleoside analogs, known to be chain-terminating inhibitors of retroviral reverse transcriptases, on Tetrahymena thermophila telomerase activity in vitro. We also analyzed the effects of such analogs on telomere length and maintenance in vivo, and on vegetative growth and mating of Tetrahymena cells. Arabinofuranyl-guanosine triphosphate (Ara-GTP) and ddGTP both efficiently inhibited telomerase activity in vitro, while azidothymidine triphosphate (AZT-TP), dideoxyinosine triphosphate (ddITP) or ddTTP were less efficient inhibitors. All of these nucleoside triphosphate analogs, however, produced analog-specific alterations of the normal banding patterns seen upon gel electrophoresis of the synthesis products of telomerase, suggesting that their chain terminating and/or competitive actions differ at different positions along the RNA template. The analogs AZT, 3'-deoxy-2',3'-didehydrothymidine (d4T) and Ara-G in nucleoside form caused consistent and rapid telomere shortening in vegetatively growing Tetrahymena. In contrast, ddG or ddI had no effect on telomere length or cell growth rates. AZT caused growth rates and viability to decrease in a fraction of cells, while Ara-G had no such effects even after several weeks in culture. Neither AZT, Ara-G, acycloguanosine (Acyclo-G), ddG nor ddI had any detectable effect on cell mating, as assayed by quantitation of the efficiency of formation of progeny from mated cells. However, AZT decreased the efficiency of programmed de novo telomere addition during macronuclear development in mating cells.

  2. Tetrahymena thermophila acidic ribosomal protein L37 contains an archaebacterial type of C-terminus

    DEFF Research Database (Denmark)

    Hansen, T S; Andreasen, P H; Dreisig, H

    1991-01-01

    We have cloned and characterized a Tetrahymena thermophila macronuclear gene (L37) encoding the acidic ribosomal protein (A-protein) L37. The gene contains a single intron located in the 3'-part of the coding region. Two major and three minor transcription start points (tsp) were mapped 39 to 63...... nucleotides upstream from the translational start codon. The uppermost tsp mapped to the first T in a putative T. thermophila RNA polymerase II initiator element, TATAA. The coding region of L37 predicts a protein of 109 amino acid (aa) residues. A substantial part of the deduced aa sequence was verified...

  3. Functional intron+ and intron- rDNA in the same macronucleus of the ciliate Tetrahymena pigmentosa

    DEFF Research Database (Denmark)

    Nielsen, Henrik; Engberg, J

    1985-01-01

    alleles was followed in the total culture and in single cells during their vegetative segregation and it was observed that replication was non-preferential with respect to the two alleles. The diallelic clones were also used to demonstrate that intron-containing rDNA was transcribed and the transcript......Diallelic clones of Tetrahymena pigmentosa containing equal amounts of intron+ and intron- rDNA in the macronucleus were constructed. The macronucleus of the resulting strains divides amitotically during vegetative growth and the diallelic genotype is therefore unstable. The coexistence of the two...

  4. Phylogenetic evidence for the acquisition of ribosomal RNA introns subsequent to the divergence of some of the major Tetrahymena groups

    DEFF Research Database (Denmark)

    Sogin, M L; Ingold, A; Karlok, M

    1986-01-01

    . In an attempt to evaluate the evolutionary origins of the intervening sequences, we have now determined complete small subunit ribosomal RNA gene sequences from 13 species of Tetrahymena and the absolute number of nucleotide differences between the sequences was used to construct a phylogenetic tree...

  5. Effects of protein kinase C activators and staurosporine on protein kinase activity, cell survival, and proliferation in Tetrahymena thermophila

    DEFF Research Database (Denmark)

    Straarup, EM; Schousboe, P; Hansen, HQ

    1997-01-01

    Autocrine factors prevent cell death in the ciliate Tetrahymena thermophila, a unicellular eukaryote, in a chemically defined medium. At certain growth conditions these factors are released at a sufficient concentration by > 500 cells ml-1 to support cell survival and proliferation. The protein k...

  6. Elucidation of clathrin-mediated endocytosis in tetrahymena reveals an evolutionarily convergent recruitment of dynamin.

    Directory of Open Access Journals (Sweden)

    Nels C Elde

    2005-11-01

    Full Text Available Ciliates, although single-celled organisms, contain numerous subcellular structures and pathways usually associated with metazoans. How this cell biological complexity relates to the evolution of molecular elements is unclear, because features in these cells have been defined mainly at the morphological level. Among these ciliate features are structures resembling clathrin-coated, endocytic pits associated with plasma membrane invaginations called parasomal sacs. The combination of genome-wide sequencing in Tetrahymena thermophila with tools for gene expression and replacement has allowed us to examine this pathway in detail. Here we demonstrate that parasomal sacs are sites of clathrin-dependent endocytosis and that AP-2 localizes to these sites. Unexpectedly, endocytosis in Tetrahymena also involves a protein in the dynamin family, Drp1p (Dynamin-related protein 1. While phylogenetic analysis of AP subunits indicates a primitive origin for clathrin-mediated endocytosis, similar analysis of dynamin-related proteins suggests, strikingly, that the recruitment of dynamin-family proteins to the endocytic pathway occurred independently during the course of the ciliate and metazoan radiations. Consistent with this, our functional analysis suggests that the precise roles of dynamins in endocytosis, as well as the mechanisms of targeting, differ in metazoans and ciliates.

  7. Elucidation of Clathrin-Mediated Endocytosis in Tetrahymena Reveals an Evolutionarily Convergent Recruitment of Dynamin.

    Directory of Open Access Journals (Sweden)

    2005-11-01

    Full Text Available Ciliates, although single-celled organisms, contain numerous subcellular structures and pathways usually associated with metazoans. How this cell biological complexity relates to the evolution of molecular elements is unclear, because features in these cells have been defined mainly at the morphological level. Among these ciliate features are structures resembling clathrin-coated, endocytic pits associated with plasma membrane invaginations called parasomal sacs. The combination of genome-wide sequencing in Tetrahymena thermophila with tools for gene expression and replacement has allowed us to examine this pathway in detail. Here we demonstrate that parasomal sacs are sites of clathrin-dependent endocytosis and that AP-2 localizes to these sites. Unexpectedly, endocytosis in Tetrahymena also involves a protein in the dynamin family, Drp1p (Dynamin-related protein 1. While phylogenetic analysis of AP subunits indicates a primitive origin for clathrin-mediated endocytosis, similar analysis of dynamin-related proteins suggests, strikingly, that the recruitment of dynamin-family proteins to the endocytic pathway occurred independently during the course of the ciliate and metazoan radiations. Consistent with this, our functional analysis suggests that the precise roles of dynamins in endocytosis, as well as the mechanisms of targeting, differ in metazoans and ciliates.

  8. Developmental regulation of DNA replication: replication fork barriers and programmed gene amplification in Tetrahymena thermophila.

    Science.gov (United States)

    Zhang, Z; Macalpine, D M; Kapler, G M

    1997-01-01

    The palindromic Tetrahymena ribosomal DNA (rDNA) minichromosome is amplified 10,000-fold during development. Subsequent vegetative replication is cell cycle regulated. rDNA replication differs fundamentally in cycling vegetative and nondividing amplifying cells. Using two-dimensional gel electrophoresis, we show for the first time that replication origins that direct gene amplification also function in normal dividing cells. Two classes of amplification intermediates were identified. The first class is indistinguishable from vegetative rDNA, initiating in just one of the two 5' nontranscribed spacer (NTS) copies in the rDNA palindrome at either of two closely spaced origins. Thus, these origins are active throughout the life cycle and their regulation changes at different developmental stages. The second, novel class of amplification intermediates is generated by multiple initiation events. Intermediates with mass greater than fully replicated DNA were observed, suggesting that onionskin replication occurs at this stage. Unlike amplified rDNA in Xenopus laevis, the novel Tetrahymena species are not produced by random initiation; replication also initiates in the 5' NTS. Surprisingly, a replication fork barrier which is activated only in these amplifying molecules blocks the progression of forks near the center of the palindrome. Whereas barriers have been previously described, this is the first instance in which programmed regulation of replication fork progression has been demonstrated in a eukaryote. PMID:9315675

  9. Tetrahymena sp. infection in guppies, Poecilia reticulata Peters: parasite characterization and pathology of infected fish.

    Science.gov (United States)

    Leibowitz, M P; Zilberg, D

    2009-10-01

    Tetrahymena sp. infection was diagnosed in guppies imported from Singapore. The parasite was isolated (Tet-NI) and optimally cultured in vitro in RM-9 medium. Cytological analyses [silver-staining and scanning electron microscopy (SEM)] revealed a pyriform-shaped, 64 x 41-microm holotrich ciliate without caudal cilium, containing a macro-nucleus (18.25 x 16.83 microm) and micro-nucleus (5.73 x 5.40 microm). Wet-mount examination and histological analyses of fish exposed to the parasite by co-habitation, immersion and infection by i.p. (intra-peritoneal) and i.m. (intra-muscular) injection revealed numerous ciliates on the skin, and in the gill and caudal fin blood vessels. Ciliates surrounded internal organs, the peri-orbital region of the eye, and were observed inside developing guppy embryos. Some muscle necrosis was associated with infection, but little or no inflammatory response. Immersion, co-habitation and i.m. injection caused relatively high infection rates and levels in the skin and tail, and lower infection in the gill blood vessels and internal organs; i.p. injection caused higher infection in the gill blood vessels and internal organs. Co-habited fish had relatively high infection levels in the hind-gut sub-mucosa. This is the first report of controlled systemic infection by Tetrahymena sp.

  10. Sodium-dependent transport of [3H](1D)chiro-inositol by Tetrahymena.

    Science.gov (United States)

    Kersting, Michael C; Ryals, Phillip E

    2004-01-01

    The transport characteristics of (1D)chiro-inositol by the ciliate Tetrahymena were examined in competition studies employing [3H](1D)chiro-inositol. (1D)chiro-Inositol transport was competed by unlabeled (1D)chiro-inositol, myo-inositol, scyllo-inositol, and D-glucose in a concentration-dependent manner. Conversely, (1D)chiro-inositol competed for [3H]myo- and [3H]scyllo-inositol transport. Lineweaver-Burke analysis of the competition data indicated a Km of 10.3 mM and a Bmax of 4.7 nmol/min/mg for (1D)chiro-inositol. Transport of (1D)chiro-inositol was inhibited by cytochalasin B, an inhibitor of facilitated glucose transporters, and phlorizin, an inhibitor of sodium-dependent transporters. Removal of sodium from the radiolabeling buffer also inhibited uptake. The presence of 0.64 mM calcium or magnesium ions exerted negligible effects on transport, although potassium was inhibitory. [3H](1D)chiro-Inositol was shown to be incorporated into Tetrahymena phosphoinositides.

  11. Transcriptome analysis of the model protozoan, Tetrahymena thermophila, using Deep RNA sequencing.

    Directory of Open Access Journals (Sweden)

    Jie Xiong

    Full Text Available BACKGROUND: The ciliated protozoan Tetrahymena thermophila is a well-studied single-celled eukaryote model organism for cellular and molecular biology. However, the lack of extensive T. thermophila cDNA libraries or a large expressed sequence tag (EST database limited the quality of the original genome annotation. METHODOLOGY/PRINCIPAL FINDINGS: This RNA-seq study describes the first deep sequencing analysis of the T. thermophila transcriptome during the three major stages of the life cycle: growth, starvation and conjugation. Uniquely mapped reads covered more than 96% of the 24,725 predicted gene models in the somatic genome. More than 1,000 new transcribed regions were identified. The great dynamic range of RNA-seq allowed detection of a nearly six order-of-magnitude range of measurable gene expression orchestrated by this cell. RNA-seq also allowed the first prediction of transcript untranslated regions (UTRs and an updated (larger size estimate of the T. thermophila transcriptome: 57 Mb, or about 55% of the somatic genome. Our study identified nearly 1,500 alternative splicing (AS events distributed over 5.2% of T. thermophila genes. This percentage represents a two order-of-magnitude increase over previous EST-based estimates in Tetrahymena. Evidence of stage-specific regulation of alternative splicing was also obtained. Finally, our study allowed us to completely confirm about 26.8% of the genes originally predicted by the gene finder, to correct coding sequence boundaries and intron-exon junctions for about a third, and to reassign microarray probes and correct earlier microarray data. CONCLUSIONS/SIGNIFICANCE: RNA-seq data significantly improve the genome annotation and provide a fully comprehensive view of the global transcriptome of T. thermophila. To our knowledge, 5.2% of T. thermophila genes with AS is the highest percentage of genes showing AS reported in a unicellular eukaryote. Tetrahymena thus becomes an excellent unicellular

  12. A community model of ciliate Tetrahymena and bacteria E. coli. Part 1: Individual-based models of Tetrahymena and E. coli populations

    Energy Technology Data Exchange (ETDEWEB)

    Jaworska, J.S.; Hallam, T.G.; Schultz, T.W. [Univ. of Tennessee, Knoxville, TN (United States)

    1996-03-01

    The dynamics of a microbial community consisting of a eucaryotic ciliate Tetrahymena pyriformis and procaryotic. Escherichia coli in a batch culture is explored by employing an individual-based approach. In this portion of the article, Part 1, population models are presented. Because both models are individual-based, models of individual organisms are developed prior to construction of the population models. The individual models use an energy budget method in which growth depends on energy gain from feeding and energy sinks such as maintenance and reproduction. These models are not limited by simplifying assumptions about constant yield, constant energy sinks and Monod growth kinetics as are traditional models of microbial organisms. Population models are generated from individual models by creating distinct individual types and assigning to each type the number of real individuals they represent. A population is a compilation of individual types that vary in a phase of cell cycle and physiological parameters such as filtering rate for ciliates and maximum anabolic rate for bacteria. An advantage of the developed models is that they realistically describe the growth of the individual cells feeding on resource which varies in density and composition. Part 2, the core of the project, integrates models into a dynamic microbial community and provides model analysis based upon available data.

  13. Product analysis illuminates the final steps of IES deletion in Tetrahymena thermophila.

    Science.gov (United States)

    Saveliev, S V; Cox, M M

    2001-06-15

    DNA sequences (IES elements) eliminated from the developing macronucleus in the ciliate Tetrahymena thermophila are released as linear fragments, which have now been detected and isolated. A PCR-mediated examination of fragment end structures reveals three types of strand scission events, reflecting three steps in the deletion process. New evidence is provided for two steps proposed previously: an initiating double-stranded cleavage, and strand transfer to create a branched deletion intermediate. The fragment ends provide evidence for a previously uncharacterized third step: the branched DNA strand is cleaved at one of several defined sites located within 15-16 nucleotides of the IES boundary, liberating the deleted DNA in a linear form.

  14. Probabilistic neural network modeling of the toxicity of chemicals to Tetrahymena pyriformis with molecular fragment descriptors.

    Science.gov (United States)

    Kaiser, K L E; Niculescu, S P; Schultz, T W

    2002-03-01

    We present the results of an investigation into the use of a probabilistic neural network (PNN) based methodology to model the 48-60-h ICG50 (inhibitory concentration for population growth) sublethal toxicity to the ciliate Tetrahymena pyriformis. The information fed into the neural network is solely based on simple molecular descriptors as can be derived from the chemical structure. In contrast to most other toxicological models, the octanol/water partition coefficient is not used as an input parameter and no rules of thumb, or other substance selection-criteria, are involved. The model was trained on a 1,000 substances data set and validated using an 84 substances external test set. The associated analysis of errors confirms the excellent recognitive and predictive capabilities of the model.

  15. Fine structure and RNA synthesis of Tetrahymena during cytochalasin B inhibition of phagocytosis.

    Science.gov (United States)

    Nilsson, J R

    1977-01-01

    Cytochalasin B inhibits the formation of normal-sized food vacuoles in Tetrahymena but the cells do not starve. Treated cells differ from starved cells in that they retain a high rate of incorporation of tritiated uridine. Large numbers of smaller vacuoles, about 1 micrometer in diameter, are formed, presumably by pinocytic activity of the cytopharyngeal membrane. This effect may perhaps be due to interference with the mechanism by which food vacuoles are sealed off at the cytostome, in which microfilaments may participate. Inhibited organisms may form tubes continuous with the cytopharynx instead of separate food vacuoles. It is not clear, however, why the formation of the small vacuoles is resistant to the drug.

  16. Expression of a cell surface immobilization antigen during serotype transformation in Tetrahymena thermophila.

    Science.gov (United States)

    Williams, N E; Doerder, F P; Ron, A

    1985-08-01

    A temperature shift from 40 to 28 degrees C rapidly induced expression of a specific immobilization antigen at the cell surface in Tetrahymena thermophila. This transformation was inhibited by actinomycin D and cycloheximide but not by colchicine or cytochalasin B. The major surface antigen expressed at 28 degrees C in cells homozygous for the SerH3 allele was partially purified, and an antiserum against this preparation was raised in rabbits. Electrophoresis, immunoblot, and [35S]methionine incorporation studies are reported which support the conclusion that the H3 antigen is an acidic protein with an Mr of approximately 52,000 daltons. An induced synthesis of the H3 immobilization antigen was detected within 30 min after a shift from 40 to 28 degrees C. This protein appeared to be synthesized in the microsomal fraction and transferred without cleavage to the cell surface, where it was inserted first into nonciliated regions.

  17. Transgenerational function of Tetrahymena Piwi protein Twi8p at distinctive noncoding RNA loci.

    Science.gov (United States)

    Farley, Brian M; Collins, Kathleen

    2017-04-01

    Transgenerational transmission of genome-regulatory epigenetic information can determine phenotypes in the progeny of sexual reproduction. Sequence specificity of transgenerational regulation derives from small RNAs assembled into Piwi-protein complexes. Known targets of transgenerational regulation are primarily transposons and transposon-derived sequences. Here, we extend the scope of Piwi-mediated transgenerational regulation to include unique noncoding RNA loci. Ciliates such as Tetrahymena have a phenotypically silent germline micronucleus and an expressed somatic macronucleus, which is differentiated anew from a germline genome copy in sexual reproduction. We show that the nuclear-localized Tetrahymena Piwi protein Twi8p shuttles from parental to zygotic macronuclei. Genetic elimination of Twi8p has no phenotype for cells in asexual growth. On the other hand, cells lacking Twi8p arrest in sexual reproduction with zygotic nuclei that retain the germline genome structure, without the DNA elimination and fragmentation required to generate a functional macronucleus. Twi8p-bound small RNAs originate from long-noncoding RNAs with a terminal hairpin, which become detectable in the absence of Twi8p. Curiously, the loci that generate Twi8p-bound small RNAs are essential for asexual cell growth, even though Twi8 RNPs are essential only in sexual reproduction. Our findings suggest the model that Twi8 RNPs act on silent germline chromosomes to permit their conversion to expressed macronuclear chromosomes. Overall this work reveals that a Piwi protein carrying small RNAs from long-noncoding RNA loci has transgenerational function in establishing zygotic nucleus competence for gene expression. © 2017 Farley and Collins; Published by Cold Spring Harbor Laboratory Press for the RNA Society.

  18. Depletion of UBC9 Causes Nuclear Defects during the Vegetative and Sexual Life Cycles in Tetrahymena thermophila

    OpenAIRE

    Yang, Qianyi; Nasir, Amjad M.; Coyne, Robert S.; Forney, James D.

    2015-01-01

    Ubc9p is the sole E2-conjugating enzyme for SUMOylation, and its proper function is required for regulating key nuclear events such as transcription, DNA repair, and mitosis. In Tetrahymena thermophila, the genome is separated into a diploid germ line micronucleus (MIC) that divides by mitosis and a polyploid somatic macronucleus (MAC) that divides amitotically. This unusual nuclear organization provides novel opportunities for the study of SUMOylation and Ubc9p function. We identified the UB...

  19. Grazing of a Tetrahymena sp. on Adhered Bacteria in Percolated Columns Monitored by In Situ Hybridization with Fluorescent Oligonucleotide Probes

    OpenAIRE

    Eisenmann, Heinrich; Harms, Hauke; Meckenstock, Rainer; Meyer, Elisabeth I.; Zehnder, Alexander J. B.

    1998-01-01

    Predation of attached Pseudomonas putida mt2 by the small ciliate Tetrahymena sp. was investigated with a percolated column system. Grazing rates were examined under static and dynamic conditions and were compared to grazing rates in batch systems containing suspended prey. The prey densities were 2 × 108 bacteria per ml of pore space and 2 × 108 bacteria per ml of suspension, respectively. Postingestion in situ hybridization of bacteria with fluorescent oligonucleotide probes was used to qua...

  20. ADF/cofilin is not essential but is critically important for actin activities during phagocytosis in Tetrahymena thermophila.

    Science.gov (United States)

    Shiozaki, Nanami; Nakano, Kentaro; Kushida, Yasuharu; Noguchi, Taro Q P; Uyeda, Taro Q P; Wloga, Dorota; Dave, Drashti; Vasudevan, Krishna Kumar; Gaertig, Jacek; Numata, Osamu

    2013-08-01

    ADF/cofilin is a highly conserved actin-modulating protein. Reorganization of the actin cytoskeleton in vivo through severing and depolymerizing of F-actin by this protein is essential for various cellular events, such as endocytosis, phagocytosis, cytokinesis, and cell migration. We show that in the ciliate Tetrahymena thermophila, the ADF/cofilin homologue Adf73p associates with actin on nascent food vacuoles. Overexpression of Adf73p disrupted the proper localization of actin and inhibited the formation of food vacuoles. In vitro, recombinant Adf73p promoted the depolymerization of filaments made of T. thermophila actin (Act1p). Knockout cells lacking the ADF73 gene are viable but grow extremely slowly and have a severely decreased rate of food vacuole formation. Knockout cells have abnormal aggregates of actin in the cytoplasm. Surprisingly, unlike the case in animals and yeasts, in Tetrahymena, ADF/cofilin is not required for cytokinesis. Thus, the Tetrahymena model shows promise for future studies of the role of ADF/cofilin in vivo.

  1. Distinct functional roles of β-tubulin isotypes in microtubule arrays of Tetrahymena thermophila, a model single-celled organism.

    Science.gov (United States)

    Pucciarelli, Sandra; Ballarini, Patrizia; Sparvoli, Daniela; Barchetta, Sabrina; Yu, Ting; Detrich, H William; Miceli, Cristina

    2012-01-01

    The multi-tubulin hypothesis proposes that each tubulin isotype performs a unique role, or subset of roles, in the universe of microtubule function(s). To test this hypothesis, we are investigating the functions of the recently discovered, noncanonical β-like tubulins (BLTs) of the ciliate, Tetrahymena thermophila. Tetrahymena forms 17 distinct microtubular structures whose assembly had been thought to be based on single α- and β-isotypes. However, completion of the macronuclear genome sequence of Tetrahymena demonstrated that this ciliate possessed a β-tubulin multigene family: two synonymous genes (BTU1 and BTU2) encode the canonical β-tubulin, BTU2, and six genes (BLT1-6) yield five divergent β-tubulin isotypes. In this report, we examine the structural features and functions of two of the BLTs (BLT1 and BLT4) and compare them to those of BTU2. With respect to BTU2, BLT1 and BLT4 had multiple sequence substitutions in their GTP-binding sites, in their interaction surfaces, and in their microtubule-targeting motifs, which together suggest that they have specialized functions. To assess the roles of these tubulins in vivo, we transformed Tetrahymena with expression vectors that direct the synthesis of GFP-tagged versions of the isotypes. We show that GFP-BLT1 and GFP-BLT4 were not detectable in somatic cilia and basal bodies, whereas GFP-BTU2 strongly labeled these structures. During cell division, GFP-BLT1 and GFP-BLT4, but not GFP-BTU2, were incorporated into the microtubule arrays of the macronucleus and into the mitotic apparatus of the micronucleus. GFP-BLT1 also participated in formation of the microtubules of the meiotic apparatus of the micronucleus during conjugation. Partitioning of the isotypes between nuclear and ciliary microtubules was confirmed biochemically. We conclude that Tetrahymena uses a family of distinct β-tubulin isotypes to construct subsets of functionally different microtubules, a result that provides strong support for the multi

  2. Light induced toxicity reduction of silver nanoparticles to Tetrahymena Pyriformis: Effect of particle size

    Energy Technology Data Exchange (ETDEWEB)

    Shi, Junpeng; Xu, Bin; Sun, Xia; Ma, Chunyan; Yu, Changping [Institute of Urban Environment, Chinese Academy of Sciences, Jimei Road 1799, Xiamen 361021 (China); Zhang, Hongwu, E-mail: hwzhang@iue.ac.cn [Institute of Urban Environment, Chinese Academy of Sciences, Jimei Road 1799, Xiamen 361021 (China)

    2013-05-15

    Highlights: ► Small AgNPs had higher toxicity than large to Tetrahymena pyriformis under dark. ► AgNPs toxicity was decreased by light. ► The decrease of small AgNP toxicity induced by light was more notable than that of large AGNPs. ► Light can influence Ag{sup +} release from, particle size of, and aggregation of AgNPs. -- Abstract: As a result of the extensive application of silver nanoparticles (AgNPs), their potential hazards, once they are released into the natural environment, are of great concern to people. Since silver is very sensitive to light, the toxicity of AgNPs released into the natural environment will be inevitably affected by light. The aim of this study was to investigate the relationship between light, toxicity, and particle size of AgNPs and deduce the possible mechanism of any interaction. Our study revealed that there was negative correlation between the particle size and the toxicity: small AgNPs (5–10 nm) had higher toxicity than large AgNPs (15–25 nm) to Tetrahymena pyriformis (T. pyriformis) under dark condition. Comparing the size dependent AgNPs toxicity under dark and light conditions, the effect of light to size dependent AgNPs toxicity was ascertained. The results indicated that AgNPs toxicity was decreased by light and the most important discovery was that the change of size dependent AgNPs toxicity had significant difference under light irradiation. The decrease of small AgNPs toxicity induced by light was more notable than large AgNPs. The decreased level of cell toxicity for small AgNPs was 32 ± 0.7%, whereas it was only 10.6 ± 5.2% for large AgNPs kept 24 h under light irradiation. The further investigation indicated that the above changes induced by light can be attributed to the decrease of released silver ions, particle growth and aggregation of AgNPs under light irradiation. The obtained results showed that the light irradiation can promote the rapid growth of small AgNPs and result in the obvious increase of

  3. Phosphoproteomic analysis of protein phosphorylation networks in Tetrahymena thermophila, a model single-celled organism.

    Science.gov (United States)

    Tian, Miao; Chen, Xiulan; Xiong, Qian; Xiong, Jie; Xiao, Chuanle; Ge, Feng; Yang, Fuquan; Miao, Wei

    2014-02-01

    Tetrahymena thermophila is a widely used unicellular eukaryotic model organism in biological research and contains more than 1000 protein kinases and phosphatases with specificity for Ser/Thr/Tyr residues. However, only a few dozen phosphorylation sites in T. thermophila are known, presenting a major obstacle to further understanding of the regulatory roles of reversible phosphorylation in this organism. In this study, we used high-accuracy mass-spectrometry-based proteomics to conduct global and site-specific phosphoproteome profiling of T. thermophila. In total, 1384 phosphopeptides and 2238 phosphorylation sites from 1008 T. thermophila proteins were identified through the combined use of peptide prefractionation, TiO2 enrichment, and two-dimensional LC-MS/MS analysis. The identified phosphoproteins are implicated in the regulation of various biological processes such as transport, gene expression, and mRNA metabolic process. Moreover, integrated analysis of the T. thermophila phosphoproteome and gene network revealed the potential biological functions of many previously unannotated proteins and predicted some putative kinase-substrate pairs. Our data provide the first global survey of phosphorylation in T. thermophila using a phosphoproteomic approach and suggest a wide-ranging regulatory scope of this modification. The provided dataset is a valuable resource for the future understanding of signaling pathways in this important model organism.

  4. Machine learning-based models to predict modes of toxic action of phenols to Tetrahymena pyriformis.

    Science.gov (United States)

    Castillo-Garit, J A; Casañola-Martin, G M; Barigye, S J; Pham-The, H; Torrens, F; Torreblanca, A

    2017-09-01

    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. Four machine learning techniques (ML), k-nearest neighbours, support vector machine, classification trees, and artificial neural networks, have been used to develop several models with higher accuracies and predictive capabilities for distinguishing between four MOAs. They showed global accuracy values between 95.9% and 97.7% and area under Receiver Operator Curve values between 0.978 and 0.998; additionally, false alarm rate values were below 8.2% for training set. In order to validate our models, cross-validation (10-folds-out) and external test-set were performed with good behaviour in all cases. These models, obtained with ML techniques, were compared with others previously reported by other researchers, and the improvement was significant.

  5. Characterization of the Tetrahymena ribozyme folding pathway using the kinetic footprinting reagent peroxynitrous acid.

    Science.gov (United States)

    Chaulk, S G; MacMillan, A M

    2000-01-11

    Large RNAs fold into complex structures which determine their biological activities. A full understanding of both RNA structure and dynamics will include the description of the pathways by which these structures are formed. Kinetic footprinting [Sclavi, B., et al. (1997) J. Mol. Biol. 266, 144-159] has been shown to be a powerful method for the study of dynamic processes involving RNA. Here we describe the use of a readily available reagent, peroxynitrous acid, as a kinetic footprinting tool for the study of RNA folding. Hydroxyl radicals generated from this reagent were used to footprint the Tetrahymena ribozyme during its magnesium-dependent folding-in agreement with synchroton X-ray footprinting [Sclavi, B., et al. (1998) Science 279, 1940-1943] and oligonucleotide/hybridization cleavage experiments [Zarrinkar, P. P., and Williamson, J. R. (1994) Science 265, 918-924], this work suggests an ordered, hierarchical folding pathway for the ribozyme. Several slow steps in the folding pathway were observed in the peroxynitrous acid footprinting, but none of these corresponded to the rate-determining step of folding. This suggests that the formation of the global, protected structure is followed by one or more slow local rearrangements to yield the final active structure. These studies illustrate the utility of peroxynitrous acid as a reagent for the elucidation of RNA folding pathways and the study of RNA dynamics.

  6. Is Evolution of Mating Preferences Inevitable? Random Mating in the Multisex System of Tetrahymena thermophila

    Directory of Open Access Journals (Sweden)

    Sujal S. Phadke

    2012-01-01

    Full Text Available Ciliate mating systems are highly diversified, providing unique opportunities to study sexual differentiation and its implications for mating dynamics. Many species of ciliates have multiple (>2 sexes. More sexes may mean more choice and an opportunity for evolution of preferential mating. We asked if the multiple sexes of the ciliate Tetrahymena thermophila mate preferentially among each other. We quantified pairing frequencies among four sexes of T. thermophila using experiments that allowed the sexes to compete as mating partners. We found that all sexes mated equally frequently among each other, that is, we found no evidence of preferential mating with respect to sex. This suggests that the “mate choice” in this ciliate is binary, between whether to form a pair or not and, in this regard, sex facilitates only self-/non-self-distinction. Thus, presence of multiple sexes does not necessarily result in the evolution of mating bias, which could decrease the maximum amount of mating that would otherwise be possible in a population. Our result of random mating verifies a key assumption in the theoretical model of sex ratio evolution in T. thermophila. Investigation into molecular differences between the sexes will be necessary to reveal the mechanistic basis of random mating among them.

  7. Delineating cellular interactions between ciliates and fish by co-culturing Tetrahymena thermophila with fish cells.

    Science.gov (United States)

    Pinheiro, Marcel D O; Bols, Niels C

    2014-10-01

    Although several species of Tetrahymena are often described as histophagous and opportunistic pathogens of fish, little is known about ciliate/fish cell interactions, but one approach for studying these is in vitro with cell lines. In this study, T. thermophila, B1975 (wild type) and NP1 (temperature sensitive mutant for phagocytosis) were cultured on monolayers of 3 fish epithelial cell lines, CHSE-214, RTgill-W1, and ZEB2J, and the rabbit kidney epithelial cell line, RK-13. Generally the ciliates flourished, whereas the monolayers died, being completely consumed over several days. The destruction of monolayers required that the ciliates could make contact with the animal cells through swimming, which appeared to dislodge or loosen cells so that they could be phagocytosed. The ciliates internalized into food vacuoles ZEB2J from cell monolayers as well as from cell suspensions. Phagocytosis was essential for monolayer destruction as monolayers remained intact under conditions where phagocytosis was impeded, such as 37°C for NP1 and 4°C for B1975. Monolayers of fish cells supported the proliferation of ciliates. Thus T. thermophila can 'eat' animal cells or be histophagous in vitro, with the potential to be histophagous in vivo. © 2014 International Federation for Cell Biology.

  8. Negative Regulators of an RNAi-Heterochromatin Positive Feedback Loop Safeguard Somatic Genome Integrity in Tetrahymena.

    Science.gov (United States)

    Suhren, Jan H; Noto, Tomoko; Kataoka, Kensuke; Gao, Shan; Liu, Yifan; Mochizuki, Kazufumi

    2017-03-07

    RNAi-mediated positive feedback loops are pivotal for the maintenance of heterochromatin, but how they are downregulated at heterochromatin-euchromatin borders is not well understood. In the ciliated protozoan Tetrahymena, heterochromatin is formed exclusively on the sequences that are removed from the somatic genome by programmed DNA elimination, and an RNAi-mediated feedback loop is important for assembling heterochromatin on the eliminated sequences. In this study, we show that the heterochromatin protein 1 (HP1)-like protein Coi6p, its interaction partners Coi7p and Lia5p, and the histone demethylase Jmj1p are crucial for confining the production of small RNAs and the formation of heterochromatin to the eliminated sequences. The loss of Coi6p, Coi7p, or Jmj1p causes ectopic DNA elimination. The results provide direct evidence for the existence of a dedicated mechanism that counteracts a positive feedback loop between RNAi and heterochromatin at heterochromatin-euchromatin borders to maintain the integrity of the somatic genome. Copyright © 2017 The Author(s). Published by Elsevier Inc. All rights reserved.

  9. In vivo synthesis of nano-selenium by Tetrahymena thermophila SB210.

    Science.gov (United States)

    Cui, Yin-Hua; Li, Ling-Li; Zhou, Nan-Qing; Liu, Jing-Hua; Huang, Qing; Wang, Hui-Juan; Tian, Jie; Yu, Han-Qing

    2016-12-01

    Nano-selenium has a great potential to be used in chemical, biological, medical and environmental fields. Biological methods for nano-selenium synthesis have attracted wide interests, because they can be operated at ambient temperature and pressure without complicated equipments. In this work, a protozoa, Tetrahymena thermophila (T. thermophila) SB210, was used to in vivo synthesize nano-selenium. The biosynthesized nano-selenium was characterized using transmission electron microscopy, energy dispersive X-ray spectroscopy and Raman spectroscopy. The synthesized amorphous spherical selenium nanoparticles had diameters of 50-500nm with the coexistence of irregular nano-selenium. The expressions of glutathione (GSH) synthesis related gene glutathione synthase, cysteine-rich protein metallothionein related gene metallothionein-1 and [2Fe-2S] cluster-binding protein related gene were up-regulated in the nano-selenium producing group. Also, the subsequent GSH detection and in vitro synthesis experimental results suggest the three proteins were likely to be involved in the nano-selenium synthesis process. Copyright © 2016 Elsevier Inc. All rights reserved.

  10. The key role of CYC2 during meiosis in Tetrahymena thermophila.

    Science.gov (United States)

    Xu, Qianlan; Wang, Ruoyu; Ghanam, A R; Yan, Guanxiong; Miao, Wei; Song, Xiaoyuan

    2016-04-01

    Meiotic recombination is carried out through a specialized pathway for the formation and repair of DNA double-strand breaks (DSBs) made by the Spo11 protein. The present study shed light on the functional role of cyclin, CYC2, in Tetrahymena thermophila which has transcriptionally high expression level during meiosis process. Knocking out the CYC2 gene results in arrest of meiotic conjugation process at 2.5-3.5 h after conjugation initiation, before the meiosis division starts, and in company with the absence of DSBs. To investigate the underlying mechanism of this phenomenon, a complete transcriptome profile was performed between wild-type strain and CYC2 knock-out strain. Functional analysis of RNA-Seq results identifies related differentially expressed genes (DEGs) including SPO11 and these DEGs are enriched in DNA repair/mismatch repair (MMR) terms in homologous recombination (HR), which indicates that CYC2 could play a crucial role in meiosis by regulating SPO11 and participating in HR.

  11. Distinct localization of a beta-tubulin epitope in the Tetrahymena thermophila and Paramecium caudatum cortex.

    Science.gov (United States)

    Libusová, L; Sulimenko, T; Sulimenko, V; Janisch, R; Hozák, P; Dráber, P

    2005-10-01

    Many of the highly organized microtubular arrangements in ciliates are located in the cortical area containing membrane vesicles and vacuoles. In Tetrahymena thermophila and Paramecium caudatum, immunofluorescence microscopy with the monoclonal antibody TU-06, directed against beta-tubulin, revealed distinct staining of this cortical region alone, while the cilia and other microtubular structures were unstained. The specificity of the antibody was confirmed by immunoblotting and by preabsorption of the antibody with purified tubulin. Double-label immunofluorescence with antibodies against gamma-tubulin, detyrosinated alpha-tubulin, and centrin showed that the TU-06 epitope is localized outside the basal body region. This was also confirmed by immunogold electron microscopy of thin sections. Proteolytic digestion of porcine brain beta-tubulin combined with a peptide scan of immobilized, overlapping peptides disclosed that the epitope was in the beta-tubulin region beta81-95, a region which is phylogenetically highly conserved. As known posttranslational modifications of beta-tubulin are located outside this area, the observed staining pattern cannot be interpreted as evidence of subcellular sequestration of modified tubulin. The limited distribution of the epitope could rather reflect the dependence of TU-06 epitope exposition on conformations of tubulin molecules in microtubule arrangements or on differential masking by interacting proteins.

  12. A model for endosymbiosis: interaction between Tetrahymena pyriformis and Escherichia coli.

    Science.gov (United States)

    Siegmund, Lisa; Burmester, Anke; Fischer, Martin S; Wöstemeyer, Johannes

    2013-11-01

    Endosymbiosis in ciliates is a common and highly diverse phenomenon in nature, but its development at the mechanistic level and the origins are not easy to understand, since these associations may have arisen at any time during evolution. Therefore a laboratory model is helpful. It could be provided by the interaction of Tetrahymena pyriformis and Escherichia coli. Microscopic analyses with a genetically manipulated fluorescent strain of E. coli show single bacteria leaving food vacuoles and escaping digestion, an important prerequisite for further experiments. Under selective conditions, beneficial for T. pyriformis, the ciliate was shown to internalize E. coli cells. After feeding, bacteria, transformed with the plasmids pBS-neoTet or pNeo4, provide T. pyriformis with the ability to handle toxic conditions, caused by the aminoglykoside antibiotic paromomycin. Axenic cultures or cocultures with untransformed bacteria show lower cell numbers and survival rates compared to cocultures with transformed bacteria after transfer to paromomycin containing media. PCR detects bacterial DNA inside T. pyriformis cells. Additionally, microscopical analysis of selectively grown cocultures reveals fluorescing particles in the cytoplasm of T. pyriformis containing DNA and lipids, corresponding in size to E. coli. This system could be a reasonable model for understanding mechanisms of endosymbiosis establishment in ciliates. Copyright © 2013 Elsevier GmbH. All rights reserved.

  13. QSAR analysis of nitroaromatics' toxicity in Tetrahymena pyriformis: structural factors and possible modes of action

    Science.gov (United States)

    Artemenko, A.G.; Muratov, E. N.; Kuz’min, V.E.; Muratov, N.N.; Varlamova, E.V.; Kuz'mina, A.V.; Gorb, L. G.; Golius, A.; Hill, F.C.; Leszczynski, J.; Tropsha, A.

    2012-01-01

    The Hierarchical Technology for Quantitative Structure - Activity Relationships (HiT QSAR) was applied to 95 diverse nitroaromatic compounds (including some widely known explosives) tested for their toxicity (50% inhibition growth concentration, IGC50) against the ciliate Tetrahymena pyriformis. The dataset was divided into subsets according to putative mechanisms of toxicity. Classification and Regression Trees (CART) approach implemented within HiT QSAR has been used for prediction of mechanism of toxicity for new compounds. The resulting models were shown to have ~80% accuracy for external datasets indicating that the mechanistic dataset division was sensible. Then, Partial Least Squares (PLS) statistical approach was used for the development of 2D QSAR models. Validated PLS models were explored to (i) elucidate the effects of different substituents in nitroaromatic compounds on toxicity; (ii) differentiate compounds by probable mechanisms of toxicity based on their structural descriptors; (iii) analyze the role of various physical-chemical factors responsible for compounds’ toxicity. Models were interpreted in terms of molecular fragments promoting or interfering with toxicity. It was also shown that mutual influence of substituents in benzene ring plays the determining role in toxicity variation. Although chemical mechanism based models were statistically significant and externally predictive (R2ext=0.64 for the external set of 63 nitroaromatics identified after all calculations have been completed), they were also shown to have limited coverage (57% for modeling and 76% for external set). PMID:21714735

  14. Effects of Pluronic F-68 on Tetrahymena cells: protection against chemical and physical stress and prolongation of survival under toxic conditions

    DEFF Research Database (Denmark)

    Hellung-Larsen, P; Assaad, F; Pankratova, Stanislava

    2000-01-01

    The effects of the non-ionic surfactant Pluronic F-68 (0.01% w/v) on Tetrahymena cells have been studied. A marked protection against chemical and physical stress was observed. The chemical stress effects were studied in cells suspended in buffer (starvation) or in buffers with added ingredients ...

  15. Comparison of primary and secondary 26S rRNA structures in two Tetrahymena species: evidence for a strong evolutionary and structural constraint in expansion segments

    DEFF Research Database (Denmark)

    Engberg, J; Nielsen, Henrik; Lenaers, G

    1990-01-01

    We have determined the nucleotide sequence of the 26S large subunit (LSU) rRNA genes for two Tetrahymena species, T. thermophila and T. pyriformis. The inferred rRNA sequences are presented in their most probable secondary structures based on compensatory mutations, energy, and conservation...

  16. ATP-binding cassette transporter enhances tolerance to DDT in Tetrahymena.

    Science.gov (United States)

    Ning, YingZhi; Dang, Huai; Liu, GuangLong; Xiong, Jie; Yuan, DongXia; Feng, LiFang; Miao, Wei

    2015-03-01

    The reuse of dichlorodiphenyltrichloroethane (DDT) as an indoor residual spray was permitted by the World Health Organization in 2007, and approximately 14 countries still use DDT to control disease vectors. The extensive exposure of insects to DDT has resulted in the emergence of DDT resistance, especially in mosquitoes, and the mechanism for this resistance in mosquitoes has been widely reported. Spraying can also introduce DDT directly into surface water, and DDT can subsequently accumulate in microorganisms, but the mechanism for the resistance to DDT degradation in microorganisms is unclear. Using whole-genome microarray analysis, we detected an abcb15 gene that was up-regulated in a specific manner by DDT treatment in T. thermophile. The deduced ABCB15 peptide sequence had two transmembrane domains (TMDs) and two nucleotide-binding domains (NBDs) to form the structure TMD-NBD-TMD-NBD, and each NBD contained three conserved motifs: Walker-A, C-loop, and Walker-B, which indicated the T. thermophila abcb15 was a typical ABC transporter gene. The expression of ABCB15 fused with a C-terminal green fluorescent protein was found to be on the periphery of the cell, suggesting that ABCB15 was a membrane pump protein. In addition, cells with abcb15 partially knocked down (abcb15-KD) grew slower than wild-type cells in the presence of 256 mg L(-1) DDT, indicating the tolerance of abcb15-KD strain to DDT exposure was decreased. Thus, we suggest that in Tetrahymena, the membrane pump protein encoded by ABCT gene abcb15 can enhance the tolerance to DDT and protect cells from this exogenous toxin by efficiently pumping it to the extracellular space.

  17. Encystment/excystment response and serotypic variation in the gastropod parasite Tetrahymena rostrata (Ciliophora, Tetrahymenidae).

    Science.gov (United States)

    Segade, P; García, N; García Estévez, J M; Arias, C; Iglesias, R

    2016-02-01

    Tetrahymena rostrata, which is characterized by a particular encystment-excystment cycle involving autogamy, has been recently found infecting the kidney of edible Helix aspersa snails under farming conditions. In this work, the effects of several factors on its encystment/excystment behaviour and the occurrence of different serotypes were investigated. The encystment/excystment response under starvation conditions was seriously affected by temperature. While a peak of encystment at 48 h followed by a progressive spontaneous excystment was observed at 18 and 25 °C, the encystment response was practically inhibited at 5 °C and clearly slowed down at 10 °C. At 30 °C, most of surviving ciliates remained encysted throughout the experiment, with spontaneous excystment being detected only after switching the temperature to 18 °C. Soil components also affected the encystment/excystment behaviour at 18 °C, with spontaneous excystment occurring in the presence of a sterile-filtered soil extract or mineral water but being strongly minimized with a non-filtered soil extract. Resting cysts formed in the latter extract exhibited a 3–4 times thicker and ultrastructurally more complex wall than that formed in mineral water and retained the excystment ability for about 4 weeks. Incomplete desiccation did not affect significantly the encystment response, while the mucus and kidney extracts from snails as well as a ciliate extract strongly stimulated a rapid excystment. Finally, two different serotypes infecting H. aspersa in heliciculture farms of Galicia (NW Spain) were identified, but no differences were observed between the encystment/excystment responses exhibited by two isolates belonging to each serotype.

  18. MtnBD is a multifunctional fusion enzyme in the methionine salvage pathway of Tetrahymena thermophila.

    Directory of Open Access Journals (Sweden)

    Toshihiro Nakano

    Full Text Available To recycle reduced sulfur to methionine in the methionine salvage pathway (MSP, 5-methylthioribulose-1-phosphate is converted to 2-keto-4-methylthiobutyrate, the methionine precursor, by four steps; dehydratase, enolase, phosphatase, and dioxygenase reactions (catalyzed by MtnB, MtnW, MtnX and MtnD, respectively, in Bacillus subtilis. It has been proposed that the MtnBD fusion enzyme in Tetrahymena thermophila catalyzes four sequential reactions from the dehydratase to dioxygenase steps, based on the results of molecular biological analyses of mutant yeast strains with knocked-out MSP genes, suggesting that new catalytic function can be acquired by fusion of enzymes. This result raises the question of how the MtnBD fusion enzyme can catalyze four very different reactions, especially since there are no homologous domains for enolase and phosphatase (MtnW and MtnX, respectively, in B. subtilis in the peptide. Here, we tried to identify the domains responsible for catalyzing the four reactions using recombinant proteins of full-length MtnBD and each domain alone. UV-visible and ¹H-NMR spectral analyses of reaction products revealed that the MtnB domain catalyzes dehydration and enolization and the MtnD domain catalyzes dioxygenation. Contrary to a previous report, conversion of 5-methylthioribulose-1-phosphate to 2-keto-4-methylthiobutyrate was dependent on addition of an exogenous phosphatase from B. subtilis. This was observed for both the MtnB domain and full-length MtnBD, suggesting that MtnBD does not catalyze the phosphatase reaction. Our results suggest that the MtnB domain of T. thermophila MtnBD acquired the new function to catalyze both the dehydratase and enolase reactions through evolutionary gene mutations, rather than fusion of MSP genes.

  19. Loading and pre-loading processes generate a distinct siRNA population in Tetrahymena

    Energy Technology Data Exchange (ETDEWEB)

    Mochizuki, Kazufumi, E-mail: kazufumi.mochizuki@imba.oeaw.ac.at; Kurth, Henriette M.

    2013-07-05

    Highlights: •The Tetrahymena Argonaute protein Twi1p binds to ∼28–30-nt siRNAs called scnRNAs. •The size of scnRNAs is determined during a pre-loading process. •The 5′ uracil bias of scnRNAs is attributed to pre-loading and loading processes. •The thermodynamic asymmetry of scnRNA duplex doesnot affect the guide strand decision. •scnRNAs may be produced non-sequentially from dsRNA substrates by Dicer. -- Abstract: The various properties of small RNAs, such as length, terminal nucleotide, thermodynamic asymmetry and duplex mismatches, can impact their sorting into different Argonaute proteins in diverse eukaryotes. The developmentally regulated 26- to 32-nt siRNAs (scnRNAs) are loaded to the Argonaute protein Twi1p and display a strong bias for uracil at the 5′ end. In this study, we used deep sequencing to analyze loaded and unloaded populations of scnRNAs. We show that the size of the scnRNA is determined during a pre-loading process, whereas their 5′ uracil bias is attributed to both pre-loading and loading processes. We also demonstrate that scnRNAs have a strong bias for adenine at the third base from the 3′ terminus, suggesting that most scnRNAs are direct Dicer products. Furthermore, we show that the thermodynamic asymmetry of the scnRNA duplex does not affect the guide and passenger strand decision. Finally, we show that scnRNAs frequently have templated uracil at the last base without a strong bias for adenine at the second base indicating non-sequential production of scnRNAs from substrates. These findings provide a biochemical basis for the varying attributes of scnRNAs, which should help improve our understanding of the production and turnover of scnRNAs in vivo.

  20. Effects of Tris(1,3-dichloro-2-propyl) Phosphate (TDCPP) in Tetrahymena Thermophila: Targeting the Ribosome

    Science.gov (United States)

    Li, Jing; Giesy, John P.; Yu, Liqin; Li, Guangyu; Liu, Chunsheng

    2015-05-01

    Tris(1,3-dichloro-2-propyl) phosphate (TDCPP) has been frequently detected in the environment, and exposure to TDCPP appears widespread. It has been implicated to cause toxicity in vertebrates, but its potential to affect lower-trophic-level species remains unknown. In the present study, the ciliated protozoan, Tetrahymena thermophila, was used as a model to evaluate toxic effects of TDCPP and explore molecular mechanisms by integrating phenotypic observation, RNA-Seq and transmission electron microscopy (TEM) Imaging technologies. Exposure to 0.01, 0.1 or 1 μM TDCPP for 5 days significantly decreased the relative biomass by reducing number of cells, size of cells and quantity of cilia in a dose-dependent manner. RNA-Seq analysis demonstrated that expression of twenty-one ribosome protein genes was down-regulated and these genes were enriched in “ribosome” term in KEGG pathway analysis. Furthermore, down-regulation of genes expressing ribosome proteins was accompanied by decreased ribosome quantity in rough endoplasmic reticulum and cytoplasm and enlarged ribosome size. Therefore, taken together, the data from the present study suggest that exposure to TDCPP affects growth and reproduction of Tetrahymena thermophila by targeting the ribosome. This information might provide insights into critical mechanisms of toxic action in other species and lead to useful bioindicators of exposure to TDCPP.

  1. Depletion of UBC9 Causes Nuclear Defects during the Vegetative and Sexual Life Cycles in Tetrahymena thermophila.

    Science.gov (United States)

    Yang, Qianyi; Nasir, Amjad M; Coyne, Robert S; Forney, James D

    2015-12-01

    Ubc9p is the sole E2-conjugating enzyme for SUMOylation, and its proper function is required for regulating key nuclear events such as transcription, DNA repair, and mitosis. In Tetrahymena thermophila, the genome is separated into a diploid germ line micronucleus (MIC) that divides by mitosis and a polyploid somatic macronucleus (MAC) that divides amitotically. This unusual nuclear organization provides novel opportunities for the study of SUMOylation and Ubc9p function. We identified the UBC9 gene and demonstrated that its complete deletion from both MIC and MAC genomes is lethal. Rescue of the lethal phenotype with a GFP-UBC9 fusion gene driven by a metallothionein promoter generated a cell line with CdCl2-dependent expression of green fluorescent protein (GFP)-Ubc9p. Depletion of Ubc9p in vegetative cells resulted in the loss of MICs, but MACs continued to divide. In contrast, expression of catalytically inactive Ubc9p resulted in the accumulation of multiple MICs. Critical roles for Ubc9p were also identified during the sexual life cycle of Tetrahymena. Cell lines that were depleted for Ubc9p did not form mating pairs and therefore could not complete any of the subsequent stages of conjugation, including meiosis and macronuclear development. Mating between cells expressing catalytically inactive Ubc9p resulted in arrest during macronuclear development, consistent with our observation that Ubc9p accumulates in the developing macronucleus. Copyright © 2015, American Society for Microbiology. All Rights Reserved.

  2. Macronuclear genome sequence of the ciliate Tetrahymena thermophila, a model eukaryote.

    Directory of Open Access Journals (Sweden)

    Jonathan A Eisen

    2006-09-01

    Full Text Available The ciliate Tetrahymena thermophila is a model organism for molecular and cellular biology. Like other ciliates, this species has separate germline and soma functions that are embodied by distinct nuclei within a single cell. The germline-like micronucleus (MIC has its genome held in reserve for sexual reproduction. The soma-like macronucleus (MAC, which possesses a genome processed from that of the MIC, is the center of gene expression and does not directly contribute DNA to sexual progeny. We report here the shotgun sequencing, assembly, and analysis of the MAC genome of T. thermophila, which is approximately 104 Mb in length and composed of approximately 225 chromosomes. Overall, the gene set is robust, with more than 27,000 predicted protein-coding genes, 15,000 of which have strong matches to genes in other organisms. The functional diversity encoded by these genes is substantial and reflects the complexity of processes required for a free-living, predatory, single-celled organism. This is highlighted by the abundance of lineage-specific duplications of genes with predicted roles in sensing and responding to environmental conditions (e.g., kinases, using diverse resources (e.g., proteases and transporters, and generating structural complexity (e.g., kinesins and dyneins. In contrast to the other lineages of alveolates (apicomplexans and dinoflagellates, no compelling evidence could be found for plastid-derived genes in the genome. UGA, the only T. thermophila stop codon, is used in some genes to encode selenocysteine, thus making this organism the first known with the potential to translate all 64 codons in nuclear genes into amino acids. We present genomic evidence supporting the hypothesis that the excision of DNA from the MIC to generate the MAC specifically targets foreign DNA as a form of genome self-defense. The combination of the genome sequence, the functional diversity encoded therein, and the presence of some pathways missing from

  3. The bifunctional dihydrofolate reductase thymidylate synthase of Tetrahymena thermophila provides a tool for molecular and biotechnology applications

    Directory of Open Access Journals (Sweden)

    Tiedtke Arno

    2006-03-01

    Full Text Available Abstract Background Dihydrofolate reductase (DHFR and thymidylate synthase (TS are crucial enzymes in DNA synthesis. In alveolata both enzymes are expressed as one bifunctional enzyme. Results Loss of this essential enzyme activities after successful allelic assortment of knock out alleles yields an auxotrophic marker in ciliates. Here the cloning, characterisation and functional analysis of Tetrahymena thermophila's DHFR-TS is presented. A first aspect of the presented work relates to destruction of DHFR-TS enzyme function in an alveolate thereby causing an auxotrophy for thymidine. A second aspect is to knock in an expression cassette encoding for a foreign gene with subsequent expression of the target protein. Conclusion This system avoids the use of antibiotics or other drugs and therefore is of high interest for biotechnological applications.

  4. Germination, growth, and sporulation of Bacillus thuringiensis subsp. israelensis in excreted food vacuoles of the protozoan Tetrahymena pyriformis.

    Science.gov (United States)

    Manasherob, R; Ben-Dov, E; Zaritsky, A; Barak, Z

    1998-05-01

    Spores of Bacillus thuringiensis subsp. israelensis and their toxic crystals are bioencapsulated in the protozoan Tetrahymena pyriformis, in which the toxin remains stable. Each T. pyriformis cell concentrates the spores and crystals in its food vacuoles, thus delivering them to mosquito larvae, which rapidly die. Vacuoles containing undigested material are later excreted from the cells. The fate of spores and toxin inside the food vacuoles was determined at various times after excretion by phase-contrast and electron microscopy as well as by viable-cell counting. Excreted food vacuoles gradually aggregated, and vegetative growth of B. thuringiensis subsp. israelensis was observed after 7 h as filaments that stemmed from the aggregates. The outgrown cells sporulated between 27 and 42 h. The spore multiplication values in this system are low compared to those obtained in carcasses of B. thuringiensis subsp. israelensis-killed larvae and pupae, but this bioencapsulation represents a new possible mode of B. thuringiensis subsp. israelensis recycling in nontarget organisms.

  5. Spliceosomal small nuclear RNAs of Tetrahymena thermophila and some possible snRNA-snRNA base-pairing interactions

    DEFF Research Database (Denmark)

    Orum, H; Nielsen, Henrik; Engberg, J

    1991-01-01

    organisms. Furthermore, secondary structures closely similar to phylogenetically proven models can be inferred from the T. thermophila data. Analysis of the snRNA sequences identifies three potential snRNA-snRNA base-pairing interactions, all of which are consistent with available phylogenetic data. Two......We have identified and characterized the full set of spliceosomal small nuclear RNAs (snRNAs; U1, U2, U4, U5 and U6) from the ciliated protozoan Tetrahymena thermophila. With the exception of U4 snRNA, the sizes of the T. thermophila snRNAs are closely similar to their metazoan homologues. The T....... thermophila snRNAs all have unique 5' ends, which start with an adenine residue. In contrast, with the exception of U6, their 3' ends show some size heterogeneity. The primary sequences of the T. thermophila snRNAs contain the sequence motifs shown, or proposed, to be of functional importance in other...

  6. Cyc17, a meiosis-specific cyclin, is essential for anaphase initiation and chromosome segregation in Tetrahymena thermophila.

    Science.gov (United States)

    Yan, Guan-Xiong; Dang, Huai; Tian, Miao; Zhang, Jing; Shodhan, Anura; Ning, Ying-Zhi; Xiong, Jie; Miao, Wei

    2016-07-17

    Although the role of cyclins in controlling nuclear division is well established, their function in ciliate meiosis remains unknown. In ciliates, the cyclin family has undergone massive expansion which suggests that diverse cell cycle systems exist, and this warrants further investigation. A screen for cyclins in the model ciliate Tetrahymena thermophila showed that there are 34 cyclins in this organism. Only 1 cyclin, Cyc17, contains the complete cyclin core and is specifically expressed during meiosis. Deletion of CYC17 led to meiotic arrest at the diakinesis-like metaphase I stage. Expression of genes involved in DNA metabolism and chromosome organization (chromatin remodeling and basic chromosomal structure) was repressed in cyc17 knockout matings. Further investigation suggested that Cyc17 is involved in regulating spindle pole attachment, and is thus essential for chromosome segregation at meiosis. These findings suggest a simple model in which chromosome segregation is influenced by Cyc17.

  7. The oral apparatus of Tetrahymena pyriformis, strain WH-6. II. Cytochalasin B inhibition of oral apparatus morphogenesis.

    Science.gov (United States)

    Gavin, R H

    1976-07-01

    The effects of cytochalasin B on oral apparatus morphogenesis and cell division were studied in synchronized Tetrahymena pyriformis, strain WH-6 syngen 1. Cytochalasin B brought about the rapid arrest of oral apparatus primordium development when added prior to the completion of oral apparatus membranelle differentiation. Cells arrested in development did not divide. When cytochalasin B was added after this transition point, oral apparatus morphogenesis and cell division were completed. The effects of cytochalasin B could be reversed by washing it from the medium. Even though cytochalasin B (at 400 mug/ml) reduced protein synthesis by 30%, the data are consistent with the interpretation that cytochalasin B prevents an assembly process during the membranelle differentiation phase of oral apparatus development.

  8. Expression of Tetrahymena snRNA gene variants including a U1 gene with mutations in the 5' splice site recognition sequence

    DEFF Research Database (Denmark)

    Eugen-Olsen, J; Hagemeister, J J; Hellung-Larsen, P

    1997-01-01

    The expression of U1, U2 and U5 snRNA gene variants has been studied under different physiological states of Tetrahymena. Variants of all three snRNA genes are expressed. Among the snRNAs detected is U1-3, a variant with 66 mutations compared to the normal U1 snRNA. Three of these mutations affec...... the 5' splice site recognition sequence. The U1-3 snRNA is present in a few hundred copies per cell. The expression of Tetrahymena snRNA genes is independent of the physiological state of the cell.......The expression of U1, U2 and U5 snRNA gene variants has been studied under different physiological states of Tetrahymena. Variants of all three snRNA genes are expressed. Among the snRNAs detected is U1-3, a variant with 66 mutations compared to the normal U1 snRNA. Three of these mutations affect...

  9. Structural organization of the genes encoding the small nuclear RNAs U1 to U6 of Tetrahymena thermophila is very similar to that of plant small nuclear RNA genes

    DEFF Research Database (Denmark)

    Orum, H; Nielsen, Henrik; Engberg, J

    1992-01-01

    We report the sequences of the genes encoding the small nuclear RNAs (snRNAs) U1 to U6 of the ciliate Tetrahymena thermophila. The genes of the individual snRNAs exist in two to six slightly different copies per haploid genome. Sequence analyses of the gene-flanking regions indicate that there ar......We report the sequences of the genes encoding the small nuclear RNAs (snRNAs) U1 to U6 of the ciliate Tetrahymena thermophila. The genes of the individual snRNAs exist in two to six slightly different copies per haploid genome. Sequence analyses of the gene-flanking regions indicate...

  10. Usual and unusual biochemical properties of ADF/cofilin-like protein Adf73p in ciliate Tetrahymena thermophila.

    Science.gov (United States)

    Shiozaki, Nanami; Nakano, Kentaro; Takaine, Masak; Abe, Hiroshi; Numata, Osamu

    2009-12-04

    Actin-depolymerizing factor (ADF)/cofilin is a well-conserved actin-modulating protein, which induces reorganization of the actin cytoskeleton by severing and depolymerizing F-actin. ADF/cofilin also binds to G-actin and inhibits nucleotide exchange, and hence, is supposed to regulate the nucleotide-bound state of the cellular G-actin pool cooperating with profilin, another well-conserved G-actin-binding protein that promotes nucleotide exchange. In this report, we investigated the biochemical properties of the ADF/cofilin-like protein Adf73p from ciliate Tetrahymena thermophila. Adf73p also binds to both G- and F-actin and severs and depolymerizes F-actin. Unlike canonical ADF/cofilin, however, Adf73p accelerates nucleotide exchange on actin and allows repolymerization of disassembled actin. These results suggest that the actin cytoskeleton of T. thermophila is regulated by Adf73p in a different way from those of mammals, plants, and yeasts.

  11. Heteroagglomeration of zinc oxide nanoparticles with clay mineral modulates the bioavailability and toxicity of nanoparticle in Tetrahymena pyriformis.

    Science.gov (United States)

    Gupta, Govind Sharan; Senapati, Violet Aileen; Dhawan, Alok; Shanker, Rishi

    2017-06-01

    The extensive use of zinc oxide nanoparticles (ZnO NPs) in cosmetics, sunscreens and healthcare products increases their release in the aquatic environment. The present study explored the possible interaction of ZnO NPs with montmorillonite clay minerals in aqueous conditions. An addition of ZnO NPs on clay suspension significantly (pclay particles from 1652±90nm to 2158±13nm due to heteroagglomeration. The electrokinetic measurements showed a significant (pclay association (-1.37±0.03μmcm/Vs) that results to the electrostatic interaction between ZnO NPs and clay particles. The attenuated total reflectance Fourier transform infrared spectroscopy analysis of ZnO NPs-clay association demonstrated the binding of ZnO NPs with the Si-O-Al region on the edges of clay particles. The increase in size of ZnO NPs-clay heteroagglomerates further leads to their sedimentation at 24h. Although, the stability of ZnO NPs in the clay suspension was decreased due to heteroagglomeration, but the bioavailability and toxicity of ZnO NPs-clay heteroagglomerates in Tetrahymena pyriformis was enhanced. These observations provide an evidence on possible mechanisms available in natural environment that can facilitate nanoparticles entry into the organisms present in lower trophic levels of the food web. Copyright © 2017 Elsevier Inc. All rights reserved.

  12. Genome-wide prediction of the polymorphic Ser gene family in Tetrahymena thermophila based on motif analysis.

    Science.gov (United States)

    Ponsuwanna, Patrath; Kümpornsin, Krittikorn; Chookajorn, Thanat

    2014-01-01

    Even though antigenic variation is employed among parasitic protozoa for host immune evasion, Tetrahymena thermophila, a free-living ciliate, can also change its surface protein antigens. These cysteine-rich glycosylphosphatidylinositol (GPI)-linked surface proteins are encoded by a family of polymorphic Ser genes. Despite the availability of T. thermophila genome, a comprehensive analysis of the Ser family is limited by its high degree of polymorphism. In order to overcome this problem, a new approach was adopted by searching for Ser candidates with common motif sequences, namely length-specific repetitive cysteine pattern and GPI anchor site. The candidate genes were phylogenetically compared with the previously identified Ser genes and classified into subtypes. Ser candidates were often found to be located as tandem arrays of the same subtypes on several chromosomal scaffolds. Certain Ser candidates located in the same chromosomal arrays were transcriptionally expressed at specific T. thermophila developmental stages. These Ser candidates selected by the motif analysis approach can form the foundation for a systematic identification of the entire Ser gene family, which will contribute to the understanding of their function and the basis of T. thermophila antigenic variation.

  13. Ecological Traits of the Algae-Bearing Tetrahymena utriculariae (Ciliophora) from Traps of the Aquatic Carnivorous Plant Utricularia reflexa.

    Science.gov (United States)

    Šimek, Karel; Pitsch, Gianna; Salcher, Michaela M; Sirová, Dagmara; Shabarova, Tanja; Adamec, Lubomír; Posch, Thomas

    2017-05-01

    Trap fluid of aquatic carnivorous plants of the genus Utricularia hosts specific microbiomes consisting of commensal pro- and eukaryotes of largely unknown ecology. We examined the characteristics and dynamics of bacteria and the three dominant eukaryotes, i.e. the algae-bearing ciliate Tetrahymena utriculariae (Ciliophora), a green flagellate Euglena agilis (Euglenophyta), and the alga Scenedesmus alternans (Chlorophyta), associated with the traps of Utricularia reflexa. Our study focused on ecological traits and life strategies of the highly abundant ciliate whose biomass by far exceeds that of other eukaryotes and bacteria independent of the trap age. The ciliate was the only bacterivore in the traps, driving rapid turnover of bacterial standing stock. However, given the large size of the ciliate and the cell-specific uptake rates of bacteria we estimated that bacterivory alone would likely be insufficient to support its apparent rapid growth in traps. We suggest that mixotrophy based on algal symbionts contributes significantly to the diet and survival strategy of the ciliate in the extreme (anaerobic, low pH) trap-fluid environment. We propose a revised concept of major microbial interactions in the trap fluid where ciliate bacterivory plays a central role in regeneration of nutrients bound in rapidly growing bacterial biomass. © 2016 The Author(s) Journal of Eukaryotic Microbiology © 2016 International Society of Protistologists.

  14. A Comparative Study of Two Quantum Chemical Descriptors in Predicting Toxicity of Aliphatic Compounds towards Tetrahymena pyriformis

    Directory of Open Access Journals (Sweden)

    Altaf Hussain Pandith

    2010-01-01

    Full Text Available Quantum chemical parameters such as LUMO energy, HOMO energy, ionization energy (I, electron affinity (A, chemical potential (μ, hardness (η electronegativity (χ, philicity (ωα, and electrophilicity (ω of a series of aliphatic compounds are calculated at the B3LYP/6-31G(d level of theory. Quantitative structure-activity relationship (QSAR models are developed for predicting the toxicity (pIGC50 of 13 classes of aliphatic compounds, including 171 electron acceptors and 81 electron donors, towards Tetrahymena pyriformis. The multiple linear regression modeling of toxicity of these compounds is performed by using the molecular descriptor log P (1-octanol/water partition coefficient in conjunction with two other quantum chemical descriptors, electrophilicity (ω and energy of the lowest unoccupied molecular orbital (ELUMO. A comparison is made towards the toxicity predicting the ability of electrophilicity (ω versus ELUMO as a global chemical reactivity descriptor in addition to log P. The former works marginally better in most cases. There is a slight improvement in the quality of regression by changing the unit of IGC50 from mg/L to molarity and by removing the racemates and the diastereoisomers from the data set.

  15. DNA content alterations in Tetrahymena pyriformis macronucleus after exposure to food preservatives sodium nitrate and sodium benzoate.

    Science.gov (United States)

    Loutsidou, Ariadni C; Hatzi, Vasiliki I; Chasapis, C T; Terzoudi, Georgia I; Spiliopoulou, Chara A; Stefanidou, Maria E

    2012-12-01

    The toxicity, in terms of changes in the DNA content, of two food preservatives, sodium nitrate and sodium benzoate was studied on the protozoan Tetrahymena pyriformis using DNA image analysis technology. For this purpose, selected doses of both food additives were administered for 2 h to protozoa cultures and DNA image analysis of T. pyriformis nuclei was performed. The analysis was based on the measurement of the Mean Optical Density which represents the cellular DNA content. The results have shown that after exposure of the protozoan cultures to doses equivalent to ADI, a statistically significant increase in the macronuclear DNA content compared to the unexposed control samples was observed. The observed increase in the macronuclear DNA content is indicative of the stimulation of the mitotic process and the observed increase in MOD, accompanied by a stimulation of the protozoan proliferation activity is in consistence with this assumption. Since alterations at the DNA level such as DNA content and uncontrolled mitogenic stimulation have been linked with chemical carcinogenesis, the results of the present study add information on the toxicogenomic profile of the selected chemicals and may potentially lead to reconsideration of the excessive use of nitrates aiming to protect public health.

  16. The C-terminal domain of Tetrahymena thermophila telomerase holoenzyme protein p65 induces multiple structural changes in telomerase RNA

    Science.gov (United States)

    Akiyama, Benjamin M.; Loper, John; Najarro, Kevin; Stone, Michael D.

    2012-01-01

    The unique cellular activity of the telomerase reverse transcriptase ribonucleoprotein (RNP) requires proper assembly of protein and RNA components into a functional complex. In the ciliate model organism Tetrahymena thermophila, the La-domain protein p65 is required for in vivo assembly of telomerase. Single-molecule and biochemical studies have shown that p65 promotes efficient RNA assembly with the telomerase reverse transcriptase (TERT) protein, in part by inducing a bend in the conserved stem IV region of telomerase RNA (TER). The domain architecture of p65 consists of an N-terminal domain, a La-RRM motif, and a C-terminal domain (CTD). Using single-molecule Förster resonance energy transfer (smFRET), we demonstrate the p65CTD is necessary for the RNA remodeling activity of the protein and is sufficient to induce a substantial conformational change in stem IV of TER. Moreover, nuclease protection assays directly map the site of p65CTD interaction to stem IV and reveal that, in addition to bending stem IV, p65 binding reorganizes nucleotides that comprise the low-affinity TERT binding site within stem–loop IV. PMID:22315458

  17. Toxicity of Nine (Doped) Rare Earth Metal Oxides and Respective Individual Metals to Aquatic Microorganisms Vibrio fischeri and Tetrahymena thermophila.

    Science.gov (United States)

    Kurvet, Imbi; Juganson, Katre; Vija, Heiki; Sihtmäe, Mariliis; Blinova, Irina; Syvertsen-Wiig, Guttorm; Kahru, Anne

    2017-07-05

    Despite the increasing use of rare earth elements (REEs) and oxides (REOs) in various technologies, the information on their ecotoxicological hazard is scarce. Here, the effects of La(3+), Ce(3+), Pr(3+), Nd(3+), Gd(3+), CeO₂, and eight doped REOs to marine bacteria Vibrio fischeri and freshwater protozoa Tetrahymena thermophila were studied in parallel with REO dopant metals (Co(2+), Fe(3+), Mn(2+), Ni(2+), Sr(2+)). The highest concentrations of REOs tested were 100 mg/L with protozoa in deionized water and 500 mg/L with bacteria in 2% NaCl. Although (i) most REOs produced reactive oxygen species; (ii) all studied soluble REEs were toxic to bacteria (half-effective concentration, EC50 3.5-21 mg metal/L; minimal bactericidal concentration, MBC 6.3-63 mg/L) and to protozoa (EC50 28-42 mg/L); and (iii) also some dopant metals (Ni(2+), Fe(3+)) proved toxic (EC50 ≤ 3 mg/L), no toxicity of REOs to protozoa (EC50 > 100 mg/L) and bacteria (EC50 > 500 mg/L; MBC > 500 mg/L) was observed except for La₂NiO₄ (MBC 25 mg/L). According to kinetics of V. fischeri bioluminescence, the toxicity of REEs was triggered by disturbing cellular membrane integrity. Fortunately, as REEs and REOs are currently produced in moderate amounts and form in the environment insoluble salts and/or oxides, they apparently present no harm to aquatic bacteria and protozoa.

  18. Lysosomal physiology in Tetrahymena. 3. Pharmacological studies on acid hydrolase release and the ingestion and egestion of dimethylbenzanthracene particles.

    Science.gov (United States)

    Rothstein, T L; Blum, J J

    1974-09-01

    The ingestion of (14)C-labeled 9,10-dimethyl-1,2-benzanthracene particles, the extracellular release of acid phosphatase, ribonuclease, and alpha-glucosidase, and the egestion of preingested dimethylbenzanthracene particles by Tetrahymena taken from logarithmically growing cultures and resuspended in a dilute salt solution were followed in the presence of several pharmacologic agents. Serotonin, caffeine, and, to a lesser extent, dibutyryl cyclic AMP increased the rate of particle ingestion, but did not alter the rate of release of the three acid hydrolases studied. Added catecholamines did not affect either particle ingestion or acid hydrolase release, but particle ingestion was inhibited by the catecholamine antagonists, dichloroisoproterenol, desmethylimipramine, reserpine, and phenoxybenzamine. These drugs also increased the release of acid phosphatase and ribonuclease in 5-h incubations. Desmethylimipramine acted within 1 h to increase acid hydrolase release, but the effect of dichloroisoproterenol developed more slowly and was secondary to a change in cellular content of the hydrolases. Desmethylimipramine increased the energy of activation for the release of acid phosphatase, while dichloroisoproterenol did not. Both of these drugs enhanced the egestion of preingested dimethylbenzanthracene particles, supporting the view that acid hydrolase release occurs through a cytoproct egestion mechanism. Particle ingestion was also inhibited by colchicine, vinblastine, and cytochalasin B, but these agents had no effect on acid hydrolase release, thus further differentiating the properties of the ingestion mechanism from those of the egestion mechanism. It appears that both microtubules and microfilaments play a role in the ingestion process and that this process may be controlled in part by a cyclic AMP-mediated serotoninergic and adrenergic system.

  19. Small phosphatidate phosphatase (TtPAH2) of Tetrahymena complements respiratory function and not membrane biogenesis function of yeast PAH1.

    Science.gov (United States)

    Pillai, Anoop Narayana; Shukla, Sushmita; Gautam, Sudhanshu; Rahaman, Abdur

    2017-12-01

    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. TtPAH2 did not rescue growth and ER/nuclear membrane defects of the pah1Δ yeast cells, suggesting that the phosphatidate phosphatase activity of the protein is not sufficient to perform these cellular functions. Surprisingly, TtPAH2 complemented the respiratory defect in the pah1Δ yeast cells indicating a specific role of TtPAH2 in respiration. Overall, our results indicate that TtPAH2 possesses the minimal function of PAH protein family in respiration. We suggest that the amino acid sequences absent from TtPAH2 but present in all other known PAH homologs are critical for lipid homeostasis and membrane biogenesis.

  20. The zinc finger protein Zfr1p is localized specifically to conjugation junction and required for sexual development in Tetrahymena thermophila.

    Directory of Open Access Journals (Sweden)

    Jing Xu

    Full Text Available Conjugation in Tetrahymena thermophila involves a developmental program consisting of three prezygotic nuclear divisions, pronuclear exchange and fusion, and postzygotic and exconjugant stages. The conjugation junction structure appears during the initiation of conjugation development, and disappears during the exconjugant stage. Many structural and functional proteins are involved in the establishment and maintenance of the junction structure in T. thermophila. In the present study, a zinc finger protein-encoding gene ZFR1 was found to be expressed specifically during conjugation and to localize specifically to the conjugation junction region. Truncated Zfr1p localized at the plasma membrane in ordered arrays and decorated Golgi apparatus located adjacent to basal body. The N-terminal zinc finger and C-terminal hydrophobic domains of Zfr1p were found to be required for its specific conjugation junction localization. Conjugation development of ZFR1 somatic knockout cells was aborted at the pronuclear exchange and fusion conjugation stages. Furthermore, Zfr1p was found to be important for conjugation junction stability during the prezygotic nuclear division stage. Taken together, our data reveal that Zfr1p is required for the stability and integrity of the conjugation junction structure and essential for the sexual life cycle of the Tetrahymena cell.

  1. Hints for Metal-Preference Protein Sequence Determinants: Different Metal Binding Features of the Five Tetrahymena thermophila Metallothioneins

    Science.gov (United States)

    Espart, Anna; Marín, Maribel; Gil-Moreno, Selene; Palacios, Òscar; Amaro, Francisco; Martín-González, Ana; Gutiérrez, Juan C.; Capdevila, Mercè; Atrian, Sílvia

    2015-01-01

    The metal binding preference of metallothioneins (MTs) groups them in two extreme subsets, the Zn/Cd- and the Cu-thioneins. Ciliates harbor the largest MT gene/protein family reported so far, including 5 paralogs that exhibit relatively low sequence similarity, excepting MTT2 and MTT4. In Tetrahymena thermophila, three MTs (MTT1, MTT3 and MTT5) were considered Cd-thioneins and two (MTT2 and MTT4) Cu-thioneins, according to gene expression inducibility and phylogenetic analysis. In this study, the metal-binding abilities of the five MTT proteins were characterized, to obtain information about the folding and stability of their cognate- and non-cognate metal complexes, and to characterize the T. thermophila MT system at protein level. Hence, the five MTTs were recombinantly synthesized as Zn2+-, Cd2+- or Cu+-complexes, which were analyzed by electrospray mass spectrometry (ESI-MS), circular dichroism (CD), and UV-vis spectrophotometry. Among the Cd-thioneins, MTT1 and MTT5 were optimal for Cd2+ coordination, yielding unique Cd17- and Cd8- complexes, respectively. When binding Zn2+, they rendered a mixture of Zn-species. Only MTT5 was capable to coordinate Cu+, although yielding heteronuclear Zn-, Cu-species or highly unstable Cu-homometallic species. MTT3 exhibited poor binding abilities both for Cd2+ and for Cu+, and although not optimally, it yielded the best result when coordinating Zn2+. The two Cu-thioneins, MTT2 and MTT4 isoforms formed homometallic Cu-complexes (major Cu20-MTT) upon synthesis in Cu-supplemented hosts. Contrarily, they were unable to fold into stable Cd-complexes, while Zn-MTT species were only recovered for MTT4 (major Zn10-MTT4). Thus, the metal binding preferences of the five T. thermophila MTs correlate well with their previous classification as Cd- and Cu-thioneins, and globally, they can be classified from Zn/Cd- to Cu-thioneins according to the gradation: MTT1>MTT5>MTT3>MTT4>MTT2. The main mechanisms underlying the evolution and

  2. In the polymorphic ciliate Tetrahymena vorax, the non-selective phagocytosis seen in microstomes changes to a highly selective process in macrostomes.

    Science.gov (United States)

    Grønlien, Heidi K; Berg, Trond; Løvlie, Arne M

    2002-07-01

    Ciliates use phagocytosis to acquire edible particles. The polymorphic ciliate Tetrahymena vorax appears in two forms ('microstomes' and 'macrostomes'). Transformation of microstomes into macrostomes takes place in the presence of the ciliate Tetrahymena thermophila and enables the macrostome to phagocytose the latter species. The non-specific, constitutive phagocytosis in microstomes thereby changes into a specific inducible process in macrostomes. The purpose of this study was to determine whether the phagocytotic process in macrostomes is specifically aimed at catching T. thermophila. The two forms of phagocytosis represent an interesting model system for studying the mechanism whereby phagosomes are formed. The macrostomal form capture deciliated and ciliated Tetrahymena thermophila, latex beads with diameters of 20.3 and 30.0 microm and small microstomal cells. However, the macrostomes select T. thermophila as a prey when they have the opportunity to choose between deciliated T. thermophila and latex beads and between T. thermophila and microstomes. The non-selective formation of phagosomes seen in microstomes changes to a highly selective process during the transformation to macrostomes. Unlike microstomes, macrostomes do not form a closed vacuole after capturing a latex bead, indicating that mechanical stimulation by the prey does not in itself trigger phagocytosis in the macrostomal form of T. vorax. Although macrostomes captured T. thermophila in preference to microstomes, phagocytosis of microstomes started immediately following capture, indicating that the substance/molecule that triggers the formation of the phagosome is not specific for T. thermophila cells. After capturing a T. thermophila cell, the macrostomal cell, which normally swims in a forward direction, reverses direction and swims backwards for a short time before starting to rotate. Macrostomal cells did not change their swimming pattern after capturing a latex bead. We believe, therefore

  3. Comparison of primary and secondary 26S rRNA structures in two Tetrahymena species: evidence for a strong evolutionary and structural constraint in expansion segments

    DEFF Research Database (Denmark)

    Engberg, J; Nielsen, Henrik; Lenaers, G

    1990-01-01

    . These are regions within the common core of secondary structure where expansions have taken place during the evolution of the rRNA of higher eukaryotes. The dispensable nature of some of the expansion segments has been taken as evidence of their non-functionality. However, our data show that a considerable......We have determined the nucleotide sequence of the 26S large subunit (LSU) rRNA genes for two Tetrahymena species, T. thermophila and T. pyriformis. The inferred rRNA sequences are presented in their most probable secondary structures based on compensatory mutations, energy, and conservation...... selective constraint has operated to preserve the secondary structure of these segments. Especially in the case of the D2 and D8 segments, the presence of a considerable number of compensatory base changes suggests that the secondary structure of these regions is of functional importance. Alternatively...

  4. Bee algorithm and adaptive neuro-fuzzy inference system as tools for QSAR study toxicity of substituted benzenes to Tetrahymena pyriformis.

    Science.gov (United States)

    Zarei, Kobra; Atabati, Morteza; Kor, Kamalodin

    2014-06-01

    A quantitative structure-activity relationship (QSAR) was developed to predict the toxicity of substituted benzenes to Tetrahymena pyriformis. A set of 1,497 zero- to three-dimensional descriptors were used for each molecule in the data set. A major problem of QSAR is the high dimensionality of the descriptor space; therefore, descriptor selection is one of the most important steps. In this paper, bee algorithm was used to select the best descriptors. Three descriptors were selected and used as inputs for adaptive neuro-fuzzy inference system (ANFIS). Then the model was corrected for unstable compounds (the compounds that can be ionized in the aqueous solutions or can easily metabolize under some conditions). Finally squared correlation coefficients were obtained as 0.8769, 0.8649 and 0.8301 for training, test and validation sets, respectively. The results showed bee-ANFIS can be used as a powerful model for prediction of toxicity of substituted benzenes to T. pyriformis.

  5. 8-Methoxypsoralen DNA interstrand cross-linking of the ribosomal RNA genes in Tetrahymena thermophila. Distribution, repair and effect on rRNA synthesis

    DEFF Research Database (Denmark)

    Fengquin, X; Nielsen, Henrik; Zhen, W

    1993-01-01

    The distribution and repair of 8-methoxypsoralen-DNA interstrand cross-links in the ribosomal RNA genes (rDNA) in Tetrahymena thermophila have been studied in vivo by Southern blot analysis. It is found that the cross-links at a density of ... between three domains (terminal spacer, transcribed region and central spacer) as defined by restriction enzyme analysis (BamHI and ClaI). It is furthermore shown that a dosage resulting in approximately one cross-link per rDNA molecule (21 kbp, two genes) is sufficient to block RNA synthesis. Finally......, it is shown that the cross-links in the rDNA molecules are repaired at equal rate in all three domains within 24 h and that RNA synthesis is partly restored during this repair period. The majority of the cells also go through one to two cell divisions in this period but do not survive....

  6. Sodium-dependent uptake of [3H]scyllo-inositol by Tetrahymena: incorporation into phosphatidylinositol, phosphatidylinositol-linked glycans, and polyphosphoinositols.

    Science.gov (United States)

    Ryals, P E; Kersting, M C

    1999-06-15

    [3H]Scyllo-inositol was taken up by Tetrahymena cells through a sodium-dependent pathway wherein unlabeled scyllo- and myo-inositol competed for uptake. d-Glucose was a competitor of [3H]myo-inositol uptake, but did not appear to compete for [3H]scyllo-inositol uptake. Transport of [3H]scyllo- and [3H]myo-inositol was inhibited when sodium was removed from the labeling buffer and by phlorizin, an inhibitor of sodium-dependent transporters. Cytochalasin B, an inhibitor of facilitated glucose transporters, had no significant effect on inositol transport. Internalized [3H]scyllo-inositol was readily incorporated intact into phosphatidylinositol, phosphatidylinositol-linked glycans, and polyphosphoinositols. Distribution of [3H]scyllo- and [3H]myo-inositol radioactivity into individual polyphosphoinositols was found to differ. Copyright 1999 Academic Press.

  7. The oral apparatus of Tetrahymena pyriformis, strain WH-6. III. The binding of 3H-cytochalasin B by the isolated oral apparatus.

    Science.gov (United States)

    Gavin, R H

    1976-07-01

    The binding of tritium-labelled cytochalasin B by the isolated oral apparatus of Tetrahymena pyriformis, strain WH-6, syngen 1, was investigated. Equilibrium binding studies revealed approximately 1.4 x 10(5) cytochalasin B binding sites per oral apparatus. A Scatchard plot indicates a single class of binding affinities with an association constant of 10(5) liters/mole. Rapid release of oral apparatus-bound cytochalasin B occurred when oral apparatuses were washed and resuspended in 1 mM TRIS without cytochalasin B. Because cytochalasin B binding to oral apparatus microtubular protein was not detected, microtubules are probably not the cytochalasin B binding site. The probable nature of the cytochalasin B binding site within the oral apparatus is discussed.

  8. Cloning and characterization of the major histone H2A genes completes the cloning and sequencing of known histone genes of Tetrahymena thermophila.

    Science.gov (United States)

    Liu, X; Gorovsky, M A

    1996-01-01

    A truncated cDNA clone encoding Tetrahymena thermophila histone H2A2 was isolated using synthetic degenerate oligonucleotide probes derived from H2A protein sequences of Tetrahymena pyriformis. The cDNA clone was used as a homologous probe to isolate a truncated genomic clone encoding H2A1. The remaining regions of the genes for H2A1 (HTA1) and H2A2 (HTA2) were then isolated using inverse PCR on circularized genomic DNA fragments. These partial clones were assembled into intact HTA1 and HTA2 clones. Nucleotide sequences of the two genes were highly homologous within the coding region but not in the noncoding regions. Comparison of the deduced amino acid sequences with protein sequences of T. pyriformis H2As showed only two and three differences respectively, in a total of 137 amino acids for H2A1, and 132 amino acids for H2A2, indicating the two genes arose before the divergence of these two species. The HTA2 gene contains a TAA triplet within the coding region, encoding a glutamine residue. In contrast with the T. thermophila HHO and HTA3 genes, no introns were identified within the two genes. The 5'- and 3'-ends of the histone H2A mRNAs; were determined by RNase protection and by PCR mapping using RACE and RLM-RACE methods. Both genes encode polyadenylated mRNAs and are highly expressed in vegetatively growing cells but only weakly expressed in starved cultures. With the inclusion of these two genes, T. thermophila is the first organism whose entire complement of known core and linker histones, including replication-dependent and basal variants, has been cloned and sequenced. PMID:8760889

  9. Genome-wide identification and evolution of ATP-binding cassette transporters in the ciliate Tetrahymena thermophila: A case of functional divergence in a multigene family

    Directory of Open Access Journals (Sweden)

    Yuan Dongxia

    2010-10-01

    Full Text Available Abstract Background In eukaryotes, ABC transporters that utilize the energy of ATP hydrolysis to expel cellular substrates into the environment are responsible for most of the efflux from cells. Many members of the superfamily of ABC transporters have been linked with resistance to multiple drugs or toxins. Owing to their medical and toxicological importance, members of the ABC superfamily have been studied in several model organisms and warrant examination in newly sequenced genomes. Results A total of 165 ABC transporter genes, constituting a highly expanded superfamily relative to its size in other eukaryotes, were identified in the macronuclear genome of the ciliate Tetrahymena thermophila. Based on ortholog comparisons, phylogenetic topologies and intron characterizations, each highly expanded ABC transporter family of T. thermophila was classified into several distinct groups, and hypotheses about their evolutionary relationships are presented. A comprehensive microarray analysis revealed divergent expression patterns among the members of the ABC transporter superfamily during different states of physiology and development. Many of the relatively recently formed duplicate pairs within individual ABC transporter families exhibit significantly different expression patterns. Further analysis showed that multiple mechanisms have led to functional divergence that is responsible for the preservation of duplicated genes. Conclusion Gene duplications have resulted in an extensive expansion of the superfamily of ABC transporters in the Tetrahymena genome, making it the largest example of its kind reported in any organism to date. Multiple independent duplications and subsequent divergence contributed to the formation of different families of ABC transporter genes. Many of the members within a gene family exhibit different expression patterns. The combination of gene duplication followed by both sequence divergence and acquisition of new patterns of

  10. Prediction of acute toxicity of phenol derivatives using multiple linear regression approach for Tetrahymena pyriformis contaminant identification in a median-size database.

    Science.gov (United States)

    Dieguez-Santana, Karel; Pham-The, Hai; Villegas-Aguilar, Pedro J; Le-Thi-Thu, Huong; Castillo-Garit, Juan A; Casañola-Martin, Gerardo M

    2016-12-01

    In this article, the modeling of inhibitory grown activity against Tetrahymena pyriformis is described. The 0-2D Dragon descriptors based on structural aspects to gain some knowledge of factors influencing aquatic toxicity are mainly used. Besides, it is done by some enlarged data of phenol derivatives described for the first time and composed of 358 chemicals. It overcomes the previous datasets with about one hundred compounds. Moreover, the results of the model evaluation by the parameters in the training, prediction and validation give adequate results comparable with those of the previous works. The more influential descriptors included in the model are: X3A, MWC02, MWC10 and piPC03 with positive contributions to the dependent variable; and MWC09, piPC02 and TPC with negative contributions. In a next step, a median-size database of nearly 8000 phenolic compounds extracted from ChEMBL was evaluated with the quantitative-structure toxicity relationship (QSTR) model developed providing some clues (SARs) for identification of ecotoxicological compounds. The outcome of this report is very useful to screen chemical databases for finding the compounds responsible of aquatic contamination in the biomarker used in the current work. Copyright © 2016 Elsevier Ltd. All rights reserved.

  11. In silico prediction of toxicity of phenols to Tetrahymena pyriformis by using genetic algorithm and decision tree-based modeling approach.

    Science.gov (United States)

    Abbasitabar, Fatemeh; Zare-Shahabadi, Vahid

    2017-04-01

    Risk assessment of chemicals is an important issue in environmental protection; however, there is a huge lack of experimental data for a large number of end-points. The experimental determination of toxicity of chemicals involves high costs and time-consuming process. In silico tools such as quantitative structure-toxicity relationship (QSTR) models, which are constructed on the basis of computational molecular descriptors, can predict missing data for toxic end-points for existing or even not yet synthesized chemicals. Phenol derivatives are known to be aquatic pollutants. With this background, we aimed to develop an accurate and reliable QSTR model for the prediction of toxicity of 206 phenols to Tetrahymena pyriformis. A multiple linear regression (MLR)-based QSTR was obtained using a powerful descriptor selection tool named Memorized_ACO algorithm. Statistical parameters of the model were 0.72 and 0.68 for R training 2 and R test 2 , respectively. To develop a high-quality QSTR model, classification and regression tree (CART) was employed. Two approaches were considered: (1) phenols were classified into different modes of action using CART and (2) the phenols in the training set were partitioned to several subsets by a tree in such a manner that in each subset, a high-quality MLR could be developed. For the first approach, the statistical parameters of the resultant QSTR model were improved to 0.83 and 0.75 for R training 2 and R test 2 , respectively. Genetic algorithm was employed in the second approach to obtain an optimal tree, and it was shown that the final QSTR model provided excellent prediction accuracy for the training and test sets (R training 2 and R test 2 were 0.91 and 0.93, respectively). The mean absolute error for the test set was computed as 0.1615. Copyright © 2016 Elsevier Ltd. All rights reserved.

  12. Gravity-dependent changes in bioconvection of Tetrahymena and Chlamydomonas during parabolic flight: increases in wave number induced by pre- and post-parabola hypergravity.

    Science.gov (United States)

    Kage, Azusa; Asato, Eriko; Chiba, Yoko; Wada, Yuuko; Katsu-Kimura, Yumiko; Kubota, Ayami; Sawai, Satoe; Niihori, Maki; Baba, Shoji A; Mogami, Yoshihiro

    2011-03-01

    Bioconvection emerges in a dense suspension of swimming protists as a consequence of their negative-gravitactic upward migration and later settling as a blob of density greater than that of water. Thus, gravity is an important parameter governing bioconvective pattern formation. However, inconsistencies are found in previous studies dealing with the response of bioconvection patterns to increased gravity acceleration (hypergravity); the wave number of the patterns has been reported to decrease during the hypergravity phases of parabolic aircraft flight, while it increases in centrifugal hypergravity. In this paper, we reassess the responses of bioconvection to altered gravity during parabolic flight on the basis of vertical and horizontal observations of the patterns formed by Tetrahymena thermophila and Chlamydomonas reinhardtii. Spatiotemporal analyses of the horizontal patterns revealed an increase in the pattern wave number in both pre- and post-parabola hypergravity. Vertical pattern analysis was generally in line with the horizontal pattern analysis, and further revealed that hypergravity-induced changes preceded at the top layer of the suspensions while microgravity-induced changes appeared to occur from the bottom part of the settling blobs. The responses to altered gravity were rather different between the two sample species: T. thermophila tended to drastically modify its bioconvection patterns in response to changes in gravity level, while the patterns of C. reinhardtii responded to a much lesser extent. This difference can be attributed to the distinct physical and physiological properties of the individual organisms, suggesting a significant contribution of the gyrotactic property to the swimming behavior of some protists.

  13. Efficient expression of codon-adapted affinity tagged super folder green fluorescent protein for synchronous protein localization and affinity purification studies in Tetrahymena thermophila.

    Science.gov (United States)

    Yilmaz, Gürkan; Arslanyolu, Muhittin

    2015-03-25

    A superior Green Fluorescent Protein (GFP) mutant, known as superfolder GFP (sfGFP), is more soluble, faster folding, and is the brightest of the known GFP mutants. This study aimed to create a codon-adapted sfGFP tag (TtsfGFP) for simultaneous protein localization and affinity purification in Tetrahymena thermophila. In vivo fluorescence spectroscopic analyses of clones carrying a codon-adapted and 6 × His tagged TtsfGFP cassette showed approximately 2-4-fold increased fluorescence emission compared with the control groups at 3 h. Fluorescence microscopy also revealed that TtsfGFP reached its emission maxima at 100 min, which was much earlier than controls expressing EGFP and sfGFP (240 min). A T. thermophila ATP-dependent DNA ligase domain containing hypothetical gene (H) was cloned into the 3' end of 6 × His-TtsfGFP to assess the affinity/localization dual tag feature. Fluorescence microscopy of the 6 × His-TtsfGFP-H clone confirmed its localization in the macro- and micronucleus of vegetative T. thermophila. Simultaneous affinity purification of TtsfGFP and TtsfGFP-H with Ni-NTA beads was feasible, as shown by Ni-NTA purified proteins analysis by SDS-PAGE and western blotting. We successfully codon adapted the N-terminal 6 × His-TtsfGFP tag and showed that it could be used for protein localization and affinity purification simultaneously in T. thermophila. We believe that this dual tag will advance T. thermophila studies by providing strong visual traceability of the target protein in vivo and in vitro during recombinant production of heterologous and homologous proteins.

  14. Listeria monocytogenes virulence factor Listeriolysin O favors bacterial growth in co-culture with the ciliate Tetrahymena pyriformis, causes protozoan encystment and promotes bacterial survival inside cysts

    Directory of Open Access Journals (Sweden)

    Ermolaeva Svetlana A

    2010-01-01

    Full Text Available Abstract Background The gram-positive pathogenic bacterium Listeria monocytogenes is widely spread in the nature. L. monocytogenes was reported to be isolated from soil, water, sewage and sludge. Listeriolysin O (LLO is a L. monocytogenes major virulence factor. In the course of infection in mammals, LLO is required for intracellular survival and apoptosis induction in lymphocytes. In this study, we explored the potential of LLO to promote interactions between L. monocytogenes and the ubiquitous inhabitant of natural ecosystems bacteriovorous free-living ciliate Tetrahymena pyriformis. Results Wild type L. monocytogenes reduced T. pyriformis trophozoite counts and stimulated encystment. The effects were observed starting from 48 h of co-incubation. On the day 14, trophozoites were eliminated from the co-culture while about 5 × 104 cells/ml remained in the axenic T. pyriformis culture. The deficient in the LLO-encoding hly gene L. monocytogenes strain failed to cause mortality among protozoa and to trigger protozoan encystment. Replenishment of the hly gene in the mutant strain restored toxicity towards protozoa and induction of protozoan encystment. The saprophytic non-haemolytic species L. innocua transformed with the LLO-expressing plasmid caused extensive mortality and encystment in ciliates. During the first week of co-incubation, LLO-producing L. monocytogenes demonstrated higher growth rates in association with T. pyriformis than the LLO-deficient isogenic strain. At latter stages of co-incubation bacterial counts were similar for both strains. T. pyriformis cysts infected with wild type L. monocytogenes caused listerial infection in guinea pigs upon ocular and oral inoculation. The infection was proved by bacterial plating from the internal organs. Conclusions The L. monocytogenes virulence factor LLO promotes bacterial survival and growth in the presence of bacteriovorous ciliate T. pyriformis. LLO is responsible for L. monocytogenes

  15. Mechanism for adaptive modification during cold acclimation of phospholipid acyl chain composition in Tetrahymena. II. Activities of 2-acyl-sn-glycerol-3-phosphorylcholine and 2-acyl-sn-glycerol-3- phosphorylethanolamine acyltransferases involving the reacylation.

    Science.gov (United States)

    Yoshioka, S; Kameyama, Y; Nozawa, Y

    1984-03-27

    The deacylation-reacylation process is very important for the alteration of phospholipid fatty acyl composition on lowering of growth temperature in Tetrahymena pyriformis (Kameyama, Y., Yoshioka, S. and Nozawa, Y., (1984) Biochim. Biophys. Acta 793, 28-33). Microsomes isolated from Tetrahymena cells have reacylation activities not only for 1-acyl-sn-glycerol-3-phosphorylcholine (1-acyl-GPC) and 1-acyl-sn-glycerol-3-phosphorylethanolamine (1-acyl-GPE) but also for 2-acyl-GPC and 2-acyl-GPE. Unsaturated fatty acyl-CoAs were in general much better substrates than saturated fatty acyl-CoAs for acylations of 1-acyl-GPC and 1-acyl-GPE. The acylation rates for 1-acyl-GPE were almost the same in palmitoleoyl-CoA, oleoyl-CoA, linoleoyl-CoA and gamma-linoleoyl-CoA. However, the acylation activity for 1-acyl-GPC was more than 2-fold higher with palmitoleoyl-CoA than with any other unsaturated fatty acyl-CoAs. In contrast, both 2-acyl-GPC and 2-acyl-GPE acyltransferases did not show a distinct preference for various acyl-CoAs, although palmitoyl-CoA was incorporated into both 2-acylphospholipids at higher rates than into 1-acylphospholipids. These specificities for various acyl-CoAs of 1-acyl- and 2-acyl-GPC and 1-acyl- and 2-acyl-GPE acyltransferases were not changed in the microsomes isolated from cells grown isothermally at 39 degrees C and 15 degrees C and cells shifted from 39 degrees C to 15 degrees C. However, the acylating ratio of linoleoyl-CoA to palmitoyl-CoA, which were chosen as typical unsaturated and saturated fatty acyl-CoAs, in the microsomes from cells grown at 15 degrees C was 1.5-3.0-times higher than in the microsomes from 39 degrees C-grown cells in four acyltransferase activities. These results suggest that the changes of acyl-CoA specificities in reacylation enzyme activities during temperature down-shift would make little contribution to the increase in unsaturated fatty acids in phospholipids, although reacylating enzymes from isothermally grown

  16. Comparative studies on the photosensitizing potency of 5-methoxypsoralen and 8-methoxypsoralen as measured by cytolysis in Paramecium caudatam and Tetrahymena pyriformis, and growth inhibition and survival in Candida albicans

    Energy Technology Data Exchange (ETDEWEB)

    Young, A.R. (Institute of Dermatology, London (UK)); Barth, J. (Karl-Marx-Universitaet, Leipzig (German Democratic Republic))

    1982-01-01

    The photosensitizing potencies of 5-methoxypsoralen and 8-methoxypsoralen were investigated using the following biological end-points for lethality: (i) cytolysis in the protozoans Paramecium caudatum and Tetrahymena pyriformis, (ii) inhibition of growth in the yeast Candida albicans and (iii) survival as measured by colony counts in Candida albicans. In all cases, 5-methoxypsoralen proved to be the more potent photosensitizing agent. The preliminary action spectra of the 2 compounds for growth inhibition in C. albicans were similar and showed maximal spectral efficiency in the 320-340 nm waveband. The molecular basis for the described end-points is unknown. Although it is well known that 5-methoxypsoralen and 8-methoxypsoralen readily photoreact with DNA, it is considered that photoreaction with protein should also be given serious consideration as the possible lethal event. The superior effect of 5-methoxypsoralen is in accordance with some of the physical and photochemical properties of this molecule, but this result is at variance with other studies in different test systems that have been used to compare the photobiological efficacy of these 2 compounds.

  17. Tetrahymena dynamin related protein 6 self assembles independent ...

    Indian Academy of Sciences (India)

    eluted as small oligomeric forms. Absence of any peak in the void volume suggests that human dynamin 1 does not form self-assembled structure under high ionic strength condition. Supplementary figure 3: Size exclusion chromatography profile of Drp6-R414A. His6-Drp6-. R414A expressed and purified from bacteria ...

  18. Highly Divergent Mitochondrial ATP Synthase Complexes in Tetrahymena thermophila

    NARCIS (Netherlands)

    Nina, Praveen Balabaskaran; Dudkina, Natalya V.; Kane, Lesley A.; van Eyk, Jennifer E.; Boekema, Egbert J.; Mather, Michael W.; Vaidya, Akhil B.; Eisen, Jonathan A.

    The F-type ATP synthase complex is a rotary nano-motor driven by proton motive force to synthesize ATP. Its F(1) sector catalyzes ATP synthesis, whereas the F(o) sector conducts the protons and provides a stator for the rotary action of the complex. Components of both F(1) and F(o) sectors are

  19. An intron in a ribosomal protein gene from Tetrahymena

    DEFF Research Database (Denmark)

    Nielsen, Henrik; Andreasen, Per Hove; Dreisig, Hanne

    1986-01-01

    of hybrid-selected mRNA and authentic ribosomal proteins. The proteins show strong homology to ribosomal protein S12 from Escherichia coli. The coding region of the gene is interrupted by a 979-bp intron 68 bp downstream of the translation start. This is the first intron in a protein encoding gene...

  20. Effects of platinic chloride on Tetrahymena pyrifromis GL

    DEFF Research Database (Denmark)

    Nilsson, Jytte R.

    1992-01-01

    Cellebiologi, platinum(IV)chloride, endocytosis, detoxification, cell proliferation, fine structure, cisplatin......Cellebiologi, platinum(IV)chloride, endocytosis, detoxification, cell proliferation, fine structure, cisplatin...

  1. Small phosphatidate phosphatase (TtPAH2) of Tetrahymena ...

    Indian Academy of Sciences (India)

    Anoop Narayana Pillai

    2017-10-03

    Oct 3, 2017 ... the color was allowed to develop. The absorbance was mea- sured at 620 nm, and the amount of phosphate produced was quantified using a standard curve. 2.11 Yeast culture conditions. Yeast cells were grown in synthetic medium (SD) containing. 2% glucose with appropriate amino acids. For growth.

  2. Sequence comparison of the rDNA introns from six different species of Tetrahymena

    DEFF Research Database (Denmark)

    Nielsen, Henrik; Engberg, J

    1985-01-01

    model for the intron RNA of Cech et al. (Proc. Natl. Acad. Sci. U.S.A. 80, 3903 (83)). Most of the sequence variation in the four new sequences reported here is found in single stranded loops in the model. However, in four cases we found nucleotide substitutions in duplex stem regions, two of them...

  3. Updating rDNA restriction enzyme maps of Tetrahymena reveals four new intron-containing species

    DEFF Research Database (Denmark)

    Nielsen, Henrik; Simon, E M; Engberg, J

    1985-01-01

    an intron in the 26s rRNA coding region. The evolutionary relationship among the species of the T. pyriformis complex was examined on the basis of the rDNA maps with emphasis on similarities between two of the new species and the widely studied T. thermophila and T. pigmentosa. Examination of a large number...

  4. Inheritance of the group I rDNA intron in Tetrahymena pigmentosa

    DEFF Research Database (Denmark)

    Nielsen, Henrik; Simon, E M; Engberg, J

    1992-01-01

    . In an analysis of vegetatively growing cells containing intron+ and intron- rDNA, initially in the same macronucleus, we similarly find no evidence of intron homing. During the course of this work, we observed to our surprise that progeny clones from some crosses contained three types of rDNA. One possible...... explanation is that T. pigmentosa has two rdn loci in contrast to the single locus found in T. thermophila. Some of the progeny clones from the genetic analysis were expanded for several hundred generations, and allelic assortment of the rDNA was demonstrated by subcloning analysis....

  5. Repair of 8-methoxypsoralen induced DNA interstrand cross-links in Tetrahymena thermophila. The effect of inhibitors of macromolecular synthesis

    DEFF Research Database (Denmark)

    Nielsen, P E; Køber, L

    1985-01-01

    : a protein-DNA complexing phase, a DNA-incision phase and finally a DNA-ligation phase. The incision was found to be completely inhibited by novobiocin (50 micrograms/ml), nalidixic acid (150 micrograms/ml), n-butyrate (15 mM) and cycloheximide (1 microgram/ml), while no effect was observed for cytosine-1......-beta-D-arabinofuranoside (10 mM), puromycin (1 mM), hydroxyurea (5 mM) or 3-aminobenzamide (2.5 mM). None of the compounds showed any effect on the protein-DNA complexing step, and the ligation was partly inhibited only by nalidixic acid (150 micrograms/ml). The involvement of topoisomerases...

  6. Critical assessment of QSAR models of environmental toxicity against Tetrahymena pyriformis: focusing on applicability domain and overfitting by variable selection.

    Science.gov (United States)

    Tetko, Igor V; Sushko, Iurii; Pandey, Anil Kumar; Zhu, Hao; Tropsha, Alexander; Papa, Ester; Oberg, Tomas; Todeschini, Roberto; Fourches, Denis; Varnek, Alexandre

    2008-09-01

    The estimation of the accuracy of predictions is a critical problem in QSAR modeling. The "distance to model" can be defined as a metric that defines the similarity between the training set molecules and the test set compound for the given property in the context of a specific model. It could be expressed in many different ways, e.g., using Tanimoto coefficient, leverage, correlation in space of models, etc. In this paper we have used mixtures of Gaussian distributions as well as statistical tests to evaluate six types of distances to models with respect to their ability to discriminate compounds with small and large prediction errors. The analysis was performed for twelve QSAR models of aqueous toxicity against T. pyriformis obtained with different machine-learning methods and various types of descriptors. The distances to model based on standard deviation of predicted toxicity calculated from the ensemble of models afforded the best results. This distance also successfully discriminated molecules with low and large prediction errors for a mechanism-based model developed using log P and the Maximum Acceptor Superdelocalizability descriptors. Thus, the distance to model metric could also be used to augment mechanistic QSAR models by estimating their prediction errors. Moreover, the accuracy of prediction is mainly determined by the training set data distribution in the chemistry and activity spaces but not by QSAR approaches used to develop the models. We have shown that incorrect validation of a model may result in the wrong estimation of its performance and suggested how this problem could be circumvented. The toxicity of 3182 and 48774 molecules from the EPA High Production Volume (HPV) Challenge Program and EINECS (European chemical Substances Information System), respectively, was predicted, and the accuracy of prediction was estimated. The developed models are available online at http://www.qspr.org site.

  7. Several RNase T2 enzymes function in induced tRNA and rRNA turnover in the ciliate Tetrahymena

    DEFF Research Database (Denmark)

    Andersen, Kasper Langebjerg; Collins, Kathleen

    2012-01-01

    RNase T2 enzymes are produced by a wide range of organisms and have been implicated to function in diverse cellular processes, including stress-induced anticodon loop cleavage of mature tRNAs to generate tRNA halves. Here we describe a family of eight RNase T2 genes (RNT2A-RNT2H) in the ciliate...... by growth arrest that functions to recycle idle protein synthesis machinery....

  8. Rapid detection of predation of Escherichia coli O157:H7 and sorting of bacterivorous tetrahymena by flow cytometry

    Science.gov (United States)

    Protozoa are known to harbor bacterial pathogens, enhance their survival in the environment and make them hypervirulent. Rapid non-culture based detection methods are required to determine the environmental transport of enteric pathogens from point sources such as dairies and feedlots to food crops ...

  9. Genome-wide identification and characterization of cytochrome P450 monooxygenase genes in the ciliate Tetrahymena thermophila

    Directory of Open Access Journals (Sweden)

    Xiong Jie

    2009-05-01

    Full Text Available Abstract Background Cytochrome P450 monooxygenases play key roles in the metabolism of a wide variety of substrates and they are closely associated with endocellular physiological processes or detoxification metabolism under environmental exposure. To date, however, none has been systematically characterized in the phylum Ciliophora. T. thermophila possess many advantages as a eukaryotic model organism and it exhibits rapid and sensitive responses to xenobiotics, making it an ideal model system to study the evolutionary and functional diversity of the P450 monooxygenase gene family. Results A total of 44 putative functional cytochrome P450 genes were identified and could be classified into 13 families and 21 sub-families according to standard nomenclature. The characteristics of both the conserved intron-exon organization and scaffold localization of tandem repeats within each P450 family clade suggested that the enlargement of T. thermophila P450 families probably resulted from recent separate small duplication events. Gene expression patterns of all T. thermophila P450s during three important cell physiological stages (vegetative growth, starvation and conjugation were analyzed based on EST and microarray data, and three main categories of expression patterns were postulated. Evolutionary analysis including codon usage preference, site-specific selection and gene-expression evolution patterns were investigated and the results indicated remarkable divergences among the T. thermophila P450 genes. Conclusion The characterization, expression and evolutionary analysis of T. thermophila P450 monooxygenase genes in the current study provides useful information for understanding the characteristics and diversities of the P450 genes in the Ciliophora, and provides the baseline for functional analyses of individual P450 isoforms in this model ciliate species.

  10. Involvement of a putative intercellular signal-recognizing G protein ...

    African Journals Online (AJOL)

    GPCRs were investigated since these receptors facilitate phagocytosis of particulates by Tetrahymena, and a GPCR apparently modulates bacterial engulfment for the pathogenic protozoan Entamoeba histolytica. A database search identified three putative Tetrahymena GPCRs, based on sequence homologies and ...

  11. Gene : CBRC-PABE-17-0002 [SEVENS

    Lifescience Database Archive (English)

    Full Text Available aining protein [Tetrahymena thermophila SB210] 1e-10 32% MYVRPPVAICPILCVLSLWGSNRMYVRPPGAICPILCVFSLWGSNHMYVRP...PGAICPILCVLSLWGANRMYVRPPVAICPILCVLSLWGSNRMYVRPPGAICPILCVFSLWGSNHMYVRPPGAICPILCVLSLWGSN...HRYLRPPGAICPILCVFSLWGSNHMYVRPPGAICPILCVLSLWGSNHRYVRPPGAIPHVIEALLISIFFLFVL ...

  12. The Green Tetrahymena utriculariae n. sp (Ciliophora, Oligohymenophorea) with Its Endosymbiotic Algae (Micractinium sp.), Living in Traps of a Carnivorous Aquatic Plant

    Czech Academy of Sciences Publication Activity Database

    Pitsch, G.; Adamec, Lubomír; Dirren, S.; Nitsche, F.; Šimek, Karel; Sirová, Dagmara; Posch, T.

    2017-01-01

    Roč. 64, č. 3 (2017), s. 322-335 ISSN 1066-5234 R&D Projects: GA ČR(CZ) GA13-00243S Institutional support: RVO:67985939 ; RVO:60077344 Keywords : Ciliata * mixotrophy * Utricularia traps Subject RIV: EE - Microbiology, Virology OBOR OECD: Microbiology Impact factor: 2.692, year: 2016

  13. Tetrahymena gene encodes a protein that is homologous with the liver-specific F-antigen and associated with membranes of the Golgi apparatus and transport vesicles

    DEFF Research Database (Denmark)

    Hummel, R; Nørgaard, P; Andreasen, P H

    1992-01-01

    of the Golgi apparatus and transport vesicles pointing to a role of TF-ag in membrane trafficking. Transcription of the TF-ag gene, as determined by run-on analyses, was only detectable in growing cells, and following transfer to starvation condition pre-existing TF-ag mRNA was rapidly degraded. The abundance...

  14. Two-dimensional agarose gel electrophoresis as a tool to isolate genus- and species-specific repetitive DNA sequences.

    Science.gov (United States)

    Harms, C; Klarholz, I; Hildebrandt, A

    2000-08-15

    Two-dimensional electrophoresis in agarose gels separates DNA-restriction fragments not only by molecular weight but also according to their AT-cluster content. The method produced genus-specific spot patterns of multicopy DNA fragments of grains as well as spot patterns of highly repetitive DNA fragments of ciliates, demonstrated for barley, spelt, and Tetrahymena. Further investigations in regard to their specificity by hybridization with three other grain species (wheat, oat, and rye) and three ciliate species (Tetrahymena thermophila, Tetrahymena pigmentosa, and Tetrahymena borealis) were performed. The DNA samples from spelt and Tetrahymena were demonstrated to be genus specific for Triticum and species specific for Tetrahymena pyriformis, respectively. Copyright 2000 Academic Press.

  15. Dicty_cDB: SLK195 [Dicty_cDB

    Lifescience Database Archive (English)

    Full Text Available 0.003 4 AF312772 |AF312772.1 Tetrahymena thermophila macronuclear immobilization antigen LC (SerLC) mRNA, pa...rtial cds. 30 0.044 3 AF312771 |AF312771.1 Tetrahymena thermophila macronuclear immobilization antigen LB (S...survey sequence. 44 1.2 1 AF312774 |AF312774.1 Tetrahymena thermophila macronuclear immobilization...hermophila macronuclear immobilization antigen LD (SerLD) mRNA, complete cds. 30 ...erLB) mRNA, complete cds. 30 0.060 3 AF312770 |AF312770.1 Tetrahymena thermophila macronuclear immobilizat

  16. NCBI nr-aa BLAST: CBRC-XTRO-01-0714 [SEVENS

    Lifescience Database Archive (English)

    Full Text Available CBRC-XTRO-01-0714 ref|XP_001008699.1| H1 immobilization antigen, putative [Tetrahym...ena thermophila SB210] gb|EAR88454.1| H1 immobilization antigen, putative [Tetrahymena thermophila SB210] XP_001008699.1 4.2 28% ...

  17. NCBI nr-aa BLAST: CBRC-XTRO-01-0480 [SEVENS

    Lifescience Database Archive (English)

    Full Text Available CBRC-XTRO-01-0480 ref|XP_001008699.1| H1 immobilization antigen, putative [Tetrahym...ena thermophila SB210] gb|EAR88454.1| H1 immobilization antigen, putative [Tetrahymena thermophila SB210] XP_001008699.1 4.2 29% ...

  18. NCBI nr-aa BLAST: CBRC-XTRO-01-0562 [SEVENS

    Lifescience Database Archive (English)

    Full Text Available CBRC-XTRO-01-0562 ref|XP_001008699.1| H1 immobilization antigen, putative [Tetrahym...ena thermophila SB210] gb|EAR88454.1| H1 immobilization antigen, putative [Tetrahymena thermophila SB210] XP_001008699.1 4.2 29% ...

  19. NCBI nr-aa BLAST: CBRC-XTRO-01-2527 [SEVENS

    Lifescience Database Archive (English)

    Full Text Available CBRC-XTRO-01-2527 ref|XP_001008699.1| H1 immobilization antigen, putative [Tetrahym...ena thermophila SB210] gb|EAR88454.1| H1 immobilization antigen, putative [Tetrahymena thermophila SB210] XP_001008699.1 4.2 29% ...

  20. NCBI nr-aa BLAST: CBRC-OLAT-12-0010 [SEVENS

    Lifescience Database Archive (English)

    Full Text Available CBRC-OLAT-12-0010 ref|XP_001032622.2| Dentin sialophosphoprotein precursor, putativ...e [Tetrahymena thermophila SB210] gb|EAR84959.2| Dentin sialophosphoprotein precursor, putative [Tetrahymena thermophila SB210] XP_001032622.2 4e-17 58% ...

  1. NCBI nr-aa BLAST: CBRC-VPAC-01-1521 [SEVENS

    Lifescience Database Archive (English)

    Full Text Available CBRC-VPAC-01-1521 ref|XP_001023022.1| Giardia variant-specific surface protein [Tet...rahymena thermophila] gb|EAS02777.1| Giardia variant-specific surface protein [Tetrahymena thermophila SB210] XP_001023022.1 0.049 24% ...

  2. NCBI nr-aa BLAST: CBRC-VPAC-01-0543 [SEVENS

    Lifescience Database Archive (English)

    Full Text Available CBRC-VPAC-01-0543 ref|XP_001023022.1| Giardia variant-specific surface protein [Tet...rahymena thermophila] gb|EAS02777.1| Giardia variant-specific surface protein [Tetrahymena thermophila SB210] XP_001023022.1 0.031 23% ...

  3. NCBI nr-aa BLAST: CBRC-VPAC-01-1582 [SEVENS

    Lifescience Database Archive (English)

    Full Text Available CBRC-VPAC-01-1582 ref|XP_001023022.1| Giardia variant-specific surface protein [Tet...rahymena thermophila] gb|EAS02777.1| Giardia variant-specific surface protein [Tetrahymena thermophila SB210] XP_001023022.1 1.3 26% ...

  4. NCBI nr-aa BLAST: CBRC-DMEL-08-0078 [SEVENS

    Lifescience Database Archive (English)

    Full Text Available CBRC-DMEL-08-0078 ref|XP_001023780.1| Phage tail fiber repeat family protein [Tetra...hymena thermophila SB210] gb|EAS03535.1| Phage tail fiber repeat family protein [Tetrahymena thermophila SB210] XP_001023780.1 1e-21 37% ...

  5. Metabolismo del glutatión y enzimas antioxidantes frente al estrés por metal(oid)es y otros agentes, en el ciliado-modelo "Tetrahymena thermophila"

    OpenAIRE

    Ortega Herrero, Ruth

    2015-01-01

    El estrés oxidativo se define como el estado celular de desequilibrio entre moléculas oxidantes y antioxidantes. Esta definición se basa en la hipótesis Redox que se desarrolla en cuatro postulados: 1)Todo sistema vivo presenta elementos redox que son moléculas ricas en residuos de cisteína y que toman parte en los procesos de señalización celular, tráfico de macromoléculas y regulación fisiológica. 2)Estos elementos se coordinan mediante circuitos redox, que tienen nodos comunes como el gl...

  6. Dicty_cDB: SLJ818 [Dicty_cDB

    Lifescience Database Archive (English)

    Full Text Available its) Value N AF312775 |AF312775.1 Tetrahymena thermophila macronuclear immobilization antigen LD (SerLD) mRN...Y9928, primer: M13 forward, sequence 1. 30 0.014 4 AF312772 |AF312772.1 Tetrahymena thermophila macronuclear immobilization...r RE70748 full insert cDNA. 42 0.096 2 AF312771 |AF312771.1 Tetrahymena thermophila macronuclear immobilization...mena thermophila macronuclear immobilization antigen LA (SerLA) mRNA, complete cds. 30 0.12 3 AC116673 |AC11

  7. Phylogenetic changes in sensitivity to Anemonia sulcata toxin (ATX II), and impact of first interaction with the toxin (imprinting) on later response to it.

    Science.gov (United States)

    Csaba, G; Dobozy, O; Darvas, Z; László, V; Beress, L

    1984-01-01

    The Anemonia sulcata toxin ATX II is cardiotoxic and neurotoxic, and--at a high dose level--even lethal for the mouse, neurotoxic, but non-lethal for the frog, and has no adverse influence whatever on the Planaria and Tetrahymena; it even stimulates the growth of the Tetrahymena at a low dose level. It also induces imprinting in the Tetrahymena, as judged from the altered response of the latter to ATX II on re-exposure. No similar imprinting effect was demonstrable in mice.

  8. Ecological impacts of umbrella effects of radiation on the individual members

    Energy Technology Data Exchange (ETDEWEB)

    Doi, Masahiro [Regulatory Sciences Research Group, Research Center for Radiation Protection, National Institute of Radiological Sciences, 4-9-1 Anagawa, Inage-ku, Chiba-shi, 263-8555 (Japan); Kawaguchi, Isao [Regulatory Sciences Research Group, Research Center for Radiation Protection, National Institute of Radiological Sciences, 4-9-1 Anagawa, Inage-ku, Chiba-shi, 263-8555 (Japan)]. E-mail: kawag@nirs.go.jp

    2007-07-15

    In order to study the interactions in a model aquatic microcosm, an individual-based computer simulation model was developed. The microcosm consists of Euglena gracilis as an autotroph algae, Tetrahymena thermophila as a heterotroph protozoa and Escherichia coli as a saprotroph bacteria. There exists a strong interaction between Tetrahymena and E. coli as the first is the predator of the second. Ecological toxicity tests were conducted to test the population level impacts of the biological effects of radiation and toxicants on the lethality and mobility factors that influence directly or indirectly growth and reproduction. Radiological effects on lethality of E. coli individuals were translated to the reduction of the equilibrium population of Tetrahymena. A synergistic effect at the community level was also observed by the simulation of a combined exposure of radiation and a toxicant which reduced the feeding efficiency of Tetrahymena.

  9. Quantum chemistry based quantitative structure-activity relationships for modeling the (sub)acute toxicity of substituted mononitrobenzenes in aquatic systems

    NARCIS (Netherlands)

    Zvinavashe, E.; Murk, A.J.; Vervoort, J.; Soffers, A.E.M.F.; Freidig, A.; Rietjens, I.M.C.M.

    2006-01-01

    Fifteen experimental literature data sets on the acute toxicity of substituted nitrobenzenes to algae (Scenedesmus obliquus, Chlorella pyrenoidosa, C. vulgaris), daphnids (Daphnia magna, D. carinata), fish (Cyprinus carpio, Poecilia reticulata), protozoa (Tetrahymena pyriformis), bacteria

  10. Dicty_cDB: SLJ752 [Dicty_cDB

    Lifescience Database Archive (English)

    Full Text Available Tetrahymena thermophila elongation factor 2 gene, complete cds. 60 1e-06 3 BM058578 |BM058578.1 2193-94 hindgut and Malpig...ditions of nitrogen deprivation. 60 1e-05 1 BM058379 |BM058379.1 2191-29 hindgut and Malpighian tubule subtr

  11. Dicty_cDB: Contig-U12991-1 [Dicty_cDB

    Lifescience Database Archive (English)

    Full Text Available ( AF272150 ) Dictyostelium discoideum deliriumA (dlrA) gene, c... 2022 0.0 3 ( BJ...39594 ) TT1EP48TV Tetrahymena thermophila SB210 cDNA libr... 38 10.0 2 >( AF272150 ) Dictyostelium discoideum delirium

  12. Introducing the Concept of Biocatalysis in the Classroom: The Conversion of Cholesterol to Provitamin D[subscript 3

    Science.gov (United States)

    De Luca, Belén M.; Nudel, Clara B.; Gonzalez, Rodrigo H.; Nusblat, Alejandro D.

    2017-01-01

    Biocatalysis is a fundamental concept in biotechnology. The topic integrates knowledge of several disciplines; therefore, it was included in the course "design and optimization of biological systems" which is offered in the biochemistry curricula. We selected the ciliate tetrahymena as an example of a eukaryotic system with potential for…

  13. Kinetic Footprinting of an RNA-Folding Pathway Using Peroxynitrous Acid.

    Science.gov (United States)

    Chaulk; MacMillan

    2000-02-01

    Following footprints to discover a path is easier with peroxynitrous acid. The folding of the Tetrahymena ribozyme was studied using this readily available reagent to generate hydroxyl radicals for kinetic footprinting studies. The different domains of the ribozyme appear to assemble at different rates following an ordered, hierarchical pathway (see scheme).

  14. An atom counting and electrophilicity based QSTR approach

    Indian Academy of Sciences (India)

    Quantitative-structure-toxicity-relationship (QSTR) models are developed for predicting the toxicity (pIGC50) of 252 aliphatic compounds on Tetrahymena pyriformis. The single parameter models with a simple molecular descriptor, the number of atoms in the molecule, provide reasonable results. Better QSTR models with ...

  15. Dicty_cDB: Contig-U15232-1 [Dicty_cDB

    Lifescience Database Archive (English)

    Full Text Available 66615 ) TTBA328TG Tetrahymena thermophila CU428 log phase... 70 1e-37 5 ( DL168374 ) Methods for Identifying...-Sampling_GS-30-02-01-1... 113 3e-37 5 ( DL171366 ) Methods for Identifying the T

  16. NCBI nr-aa BLAST: CBRC-OLAT-18-0048 [SEVENS

    Lifescience Database Archive (English)

    Full Text Available CBRC-OLAT-18-0048 ref|XP_001471091.1| two-component sensor protein histidine protein kinase (dhkk, dhkj...) [Tetrahymena thermophila SB210] gb|EDK32072.1| two-component sensor protein histidine

  17. UN-EDITED VERSION

    Indian Academy of Sciences (India)

    19

    Title: Tetrahymena dynamin related protein 6 self assembles independent of membrane association. ... proteins retain three characteristic domains but lack PRD (involved in protein-protein interactions) and the PH ..... However, the assembly interface of Drp6 seems to be different from that of Dynamins since mutants in the ...

  18. Dicty_cDB: SLJ468 [Dicty_cDB

    Lifescience Database Archive (English)

    Full Text Available ignificant alignments: (bits) Value N AF312775 |AF312775.1 Tetrahymena thermophila macronuclear immobiliza...tion antigen LD (SerLD) mRNA, complete cds. 30 0.46 4 BG632067 |BG632067.1 GH02610.

  19. Dicty_cDB: AFK467 [Dicty_cDB

    Lifescience Database Archive (English)

    Full Text Available 599 e-167 1 CN206669 |CN206669.1 Tor7097 Gametophyte rehydration Library Tortula ruralis cDNA, mRNA sequenc...55.1 TTE00006978 Normalized large Tetrahymena thermophila cDNA, mRNA sequence. 74 3e-09 1 CN206834 |CN206834.1 Tor7258 Game

  20. Dicty_cDB: AFL178 [Dicty_cDB

    Lifescience Database Archive (English)

    Full Text Available e-167 1 CN206669 |CN206669.1 Tor7097 Gametophyte rehydration Library Tortula ruralis cDNA, mRNA sequence. 7... TTE00006978 Normalized large Tetrahymena thermophila cDNA, mRNA sequence. 74 3e-09 1 CN206834 |CN206834.1 Tor7258 Game

  1. Dicty_cDB: AFK889 [Dicty_cDB

    Lifescience Database Archive (English)

    Full Text Available 599 e-167 1 CN206669 |CN206669.1 Tor7097 Gametophyte rehydration Library Tortula...55.1 TTE00006978 Normalized large Tetrahymena thermophila cDNA, mRNA sequence. 74 4e-09 1 CN206834 |CN206834.1 Tor7258 Game

  2. Dicty_cDB: AFH816 [Dicty_cDB

    Lifescience Database Archive (English)

    Full Text Available ingle read. 599 e-167 1 CN206669 |CN206669.1 Tor7097 Gametophyte rehydration Library Tortula ruralis cDNA, m... Normalized large Tetrahymena thermophila cDNA, mRNA sequence. 74 3e-09 1 CN206834 |CN206834.1 Tor7258 Gam

  3. Dicty_cDB: AFH685 [Dicty_cDB

    Lifescience Database Archive (English)

    Full Text Available 99 e-167 1 CN206669 |CN206669.1 Tor7097 Gametophyte rehydration Library Tortula ruralis cDNA, mRNA sequence.....1 TTE00006978 Normalized large Tetrahymena thermophila cDNA, mRNA sequence. 74 3e-09 1 CN206834 |CN206834.1 Tor7258 Game

  4. Dicty_cDB: AFH538 [Dicty_cDB

    Lifescience Database Archive (English)

    Full Text Available e-165 1 CN206669 |CN206669.1 Tor7097 Gametophyte rehydration Library Tortula ruralis cDNA, mRNA sequence. 7...ge Tetrahymena thermophila cDNA, mRNA sequence. 74 3e-09 1 CN206834 |CN206834.1 Tor7258 Game

  5. Co-Transport of Polycyclic Aromatic Hydrocarbons by Motile Microorganisms Leads to Enhanced Mass Transfer under Diffusive Conditions

    DEFF Research Database (Denmark)

    Gilbert, Dorthea; Jakobsen, Hans H.; Winding, Anne

    2014-01-01

    as sink and source for polycyclic aromatic hydrocarbons (PAHs). This resulted in stable concentration gradients in water (>24 h). Adding the model organism Tetrahymena pyriformis to the experimental system enhanced PAH mass transfer up to hundred-fold (benzo[a]pyrene). Increasing mass transfer enhancement...

  6. GenBank blastx search result: AK288287 [KOME

    Lifescience Database Archive (English)

    Full Text Available AK288287 J090018F21 AY740525.1 AY740525 Tetrahymena thermophila cadmium-inducible m...etallothionein 1 (MTT1) and cadmium-inducible metallothionein 3 (MTT3) genes, complete cds. INV 0.0 0 ...

  7. a QSAR Study

    African Journals Online (AJOL)

    DK

    describe a mathematical relationship between the structural features of ... Tetrahymena pyriformis. Models based on different kinds of logP (calculated values for. AlogP, MlogP and ClogP), are compared to the optimal model constructed using a single 3D ... molecular mechanics method (Polack-Ribiere algorithm). The final ...

  8. Dicty_cDB: Contig-U12426-1 [Dicty_cDB

    Lifescience Database Archive (English)

    Full Text Available 634175 ) Uncultured ectomycorrhiza (Tuber) 6098 internal t... 48 1.1 1 ( DQ927304 ) Tetrahymena paravorax st...1 ( EU202708 ) Uncultured Tuber clone Y2OM20 18S ribosomal RNA g... 48 1.1 1 ( AY

  9. Nuclear dimorphism: two peas in a pod.

    Science.gov (United States)

    Goldfarb, David S; Gorovsky, Martin A

    2009-06-09

    The macro- and micronuclei of Tetrahymena reside in the same cytoplasm but are about as different as night and day. This extreme case of nuclear dimorphism can now be partially attributed to differences in the subunit compositions of their nuclear pore complexes.

  10. A new strategy for detection and development of tractable telomerase inhibitors.

    Science.gov (United States)

    Cohn, Elysia P M T; Wu, Kun-Liang; Pettus, Thomas R R; Reich, Norbert O

    2012-04-26

    Despite intense academic and industrial efforts and innumerable in vitro and cell studies, no small-molecule telomerase inhibitors have emerged as drugs. Insufficient understanding of enzyme structure and mechanisms of interdiction coupled with the substantial complexities presented by its dimeric composition have stalled all progress toward small-molecule therapeutics. Here we challenge the assumption that human telomerase provides the best platform for inhibitor development by probing a monomeric Tetrahymena telomerase with six tool compounds. We find BIBR-1532 (2) and MST-312 (5) inhibit only human telomerase, whereas β-R (1), THyF (3), TMPyP4 (6), and EGCG (4) inhibit both enzymes. Our study demonstrates that some small-molecule scaffolds can be easily surveyed with in vitro studies using Tetrahymena telomerase, a finding that could lead to more tractable inhibitors with a greater potential for development given the more precise insights that can be gleaned from this more easily expressed and assayed monomeric enzyme.

  11. Members of the NIMA-related kinase family promote disassembly of cilia by multiple mechanisms.

    Science.gov (United States)

    Wloga, Dorota; Camba, Amy; Rogowski, Krzysztof; Manning, Gerard; Jerka-Dziadosz, Maria; Gaertig, Jacek

    2006-06-01

    The genome of Tetrahymena thermophila contains 39 loci encoding NIMA-related kinases (NRKs), an extraordinarily large number for a unicellular organism. Evolutionary analyses grouped these sequences into several subfamilies, some of which have orthologues in animals, whereas others are protist specific. When overproduced, NRKs of three subfamilies caused rapid shortening of cilia. Ultrastructural studies revealed that each NRK triggered ciliary resorption by a distinct mechanism that involved preferential depolymerization of a subset of axonemal microtubules, at either the distal or proximal end. Overexpression of a kinase-inactive variant caused lengthening of cilia, indicating that constitutive NRK-mediated resorption regulates the length of cilia. Each NRK preferentially resorbed a distinct subset of cilia, depending on the location along the anteroposterior axis. We also show that normal Tetrahymena cells maintain unequal length cilia. We propose that ciliates used a large number of NRK paralogues to differentially regulate the length of specific subsets of cilia in the same cell.

  12. The mitochondrial genomes of the ciliates Euplotes minuta and Euplotes crassus

    Directory of Open Access Journals (Sweden)

    Huynh Minh

    2009-11-01

    Full Text Available Abstract Background There are thousands of very diverse ciliate species from which only a handful mitochondrial genomes have been studied so far. These genomes are rather similar because the ciliates analysed (Tetrahymena spp. and Paramecium aurelia are closely related. Here we study the mitochondrial genomes of the hypotrichous ciliates Euplotes minuta and Euplotes crassus. These ciliates are only distantly related to Tetrahymena spp. and Paramecium aurelia, but more closely related to Nyctotherus ovalis, which possesses a hydrogenosomal (mitochondrial genome. Results The linear mitochondrial genomes of the hypotrichous ciliates Euplotes minuta and Euplotes crassus were sequenced and compared with the mitochondrial genomes of several Tetrahymena species, Paramecium aurelia and the partially sequenced mitochondrial genome of the anaerobic ciliate Nyctotherus ovalis. This study reports new features such as long 5'gene extensions of several mitochondrial genes, extremely long cox1 and cox2 open reading frames and a large repeat in the middle of the linear mitochondrial genome. The repeat separates the open reading frames into two blocks, each having a single direction of transcription, from the repeat towards the ends of the chromosome. Although the Euplotes mitochondrial gene content is almost identical to that of Paramecium and Tetrahymena, the order of the genes is completely different. In contrast, the 33273 bp (excluding the repeat region piece of the mitochondrial genome that has been sequenced in both Euplotes species exhibits no difference in gene order. Unexpectedly, many of the mitochondrial genes of E. minuta encoding ribosomal proteins possess N-terminal extensions that are similar to mitochondrial targeting signals. Conclusion The mitochondrial genomes of the hypotrichous ciliates Euplotes minuta and Euplotes crassus are rather different from the previously studied genomes. Many genes are extended in size compared to mitochondrial

  13. DNA damage by the cobalt (II) and zinc (II) complexes of ...

    African Journals Online (AJOL)

    Using the single cell gel electrophoresis method, the tetraazamacrocycle Zn(II) complex (Zn(II)-L) and the tetraazamacrocycle Co(II) complex (Co(II)-L) were investigated focusing on their DNA damage to Tetrahymena thermophila. When the cells were treated with the 0.05, 0.25 and 0.50 mg/ml Zn(II)-L, the tail length ...

  14. DNA rearrangements directed by non-coding RNAs in ciliates

    OpenAIRE

    Mochizuki, Kazufumi

    2010-01-01

    Extensive programmed rearrangement of DNA, including DNA elimination, chromosome fragmentation, and DNA descrambling, takes place in the newly developed macronucleus during the sexual reproduction of ciliated protozoa. Recent studies have revealed that two distant classes of ciliates use distinct types of non-coding RNAs to regulate such DNA rearrangement events. DNA elimination in Tetrahymena is regulated by small non-coding RNAs that are produced and utilized in an RNAi-related process. It ...

  15. DNA damage by the cobalt (II) and zinc (II) complexes of ...

    African Journals Online (AJOL)

    STORAGESEVER

    2008-09-03

    Sep 3, 2008 ... Using the single cell gel electrophoresis method, the tetraazamacrocycle Zn(II) complex (Zn(II)-L) and the tetraazamacrocycle Co(II) complex (Co(II)-L) were investigated focusing on their DNA damage to. Tetrahymena thermophila. When the cells were treated with the 0.05, 0.25 and 0.50 mg/ml Zn(II)-L, the.

  16. Dicty_cDB: VHB207 [Dicty_cDB

    Lifescience Database Archive (English)

    Full Text Available Tetrahymena thermophila cDNA clone TT1C849, mRNA sequence. 68 1e-11 2 CF445056 |CF445056.1 EST681401 normalized cDNA library of onio...1 3 CF439652 |CF439652.1 EST675997 normalized cDNA library of onion Allium cepa cDNA clone ACAAS01, mRNA seq

  17. Morphological and molecular characterization of renal ciliates infecting farmed snails in Spain.

    Science.gov (United States)

    Segade, P; Kher, C P; Lynn, D H; Iglesias, R

    2009-06-01

    Renal infections by parasitic ciliates were studied in adult snails of Helix aspersa aspersa and Helix aspersa maxima collected from 2 mixed rearing system-based heliciculture farms located in Galicia (NW Spain). The occurrence of ciliates was also examined in slugs (Deroceras reticulatum) invading the greenhouses where first growing and fattening of snails is carried out. Histological examinations revealed a severe destruction of the renal epithelium in heavily infected hosts. Three ciliate isolates, one from each host species, were obtained and grown in axenic cultures. Cultured and parasitic ciliates were characterized morphologically and morphometrically. In addition, the encystment behaviour, the occurrence of autogamy, and the sequences of the mitochondrial cytochrome-c oxidase subunit 1 (cox1) and the small subunit ribosomal RNA (SSU rRNA) genes were also studied in the 3 isolates. A polymorphic life cycle involving resting and reproductive cysts, together with the morphological and morphometrical characteristics and the confirmation that autogamy occurs within cysts, demonstrate that our ciliates belong to the species Tetrahymena rostrata (Kahl, 1926) Corliss, 1952. The 3 isolates formed a well-supported clade using both genetic markers, and were clearly separate from the strain ATCC(R) 30770, which has been identified as Tetrahymena rostrata. We argue that our Spanish isolates should be regarded as Tetrahymena rostrata, and that the ATCC isolate should be regarded as a misidentification as neither cytological nor cytogenetical support for its identity has been presented.

  18. Telomerase-Associated Protein TEP1 Is Not Essential for Telomerase Activity or Telomere Length Maintenance In Vivo

    OpenAIRE

    Liu, Yie; Snow, Bryan E.; Hande, M. Prakash; Baerlocher, Gabriela; Kickhoefer, Valerie A.; Yeung, David; Wakeham, Andrew; Itie, Annick; Siderovski, David P.; Lansdorp, Peter M.; Robinson, Murray O.; Harrington, Lea

    2000-01-01

    TEP1 is a mammalian telomerase-associated protein with similarity to the Tetrahymena telomerase protein p80. Like p80, TEP1 is associated with telomerase activity and the telomerase reverse transcriptase, and it specifically interacts with the telomerase RNA. To determine the role of mTep1 in telomerase function in vivo, we generated mouse embryonic stem (ES) cells and mice lacking mTep1. The mTep1-deficient (mTep1−/−) mice were viable and were bred for seven successive generations with no ob...

  19. Biochemical approaches including the design and use of strains expressing epitope-tagged proteins.

    Science.gov (United States)

    Couvillion, Mary T; Collins, Kathleen

    2012-01-01

    Epitope tagging is a powerful approach used to enable investigations of a cellular component by elucidating its localization, interaction partners, and/or activity targets. Successful tag-based affinity purification yields a mixture of the molecule of interest, associated proteins and nucleic acids, and nonspecific background proteins and nucleic acids, many of which can depend on details of the protocol for enrichment. This chapter provides guidelines and considerations for designing an affinity purification experiment, beginning with construction of a strain expressing a tagged subunit. Common biochemical methods for detecting protein, RNA, and DNA in Tetrahymena thermophila are also discussed. Copyright © 2012 Elsevier Inc. All rights reserved.

  20. Dicty_cDB: Contig-U01495-1 [Dicty_cDB

    Lifescience Database Archive (English)

    Full Text Available e DKEY-254E13 in ... 38 0.021 5 ( AF442957 ) Ostrinia nubilalis mitochondrion, comple... ( AM285305 ) Spiroplasma citri GII3-3X chromosome, contig Cont... 38 0.002 8 ( AM482600 ) Vitis vinifera...coideum slug cDNA, clone SLA854. 38 0.019 3 ( AL929356 ) Plasmodium falciparum strain... PROGRESS *** f... 42 0.044 8 ( DQ927305 ) Tetrahymena pigmentosa strain UM1060 mitochondrio... 38 0.044 7 (... 6632935. 32 0.13 13 ( BA000003 ) Buchnera aphidicola str. APS (Acyrthosiphon pisum... 32 0.13 13 ( DE879038 ) Macropus eugeni

  1. Ecological impacts of environmental toxicants and radiation on the microbial ecosystem: a model simulation of computational microbiology

    Energy Technology Data Exchange (ETDEWEB)

    Doi, Masahiro; Sakashita, Tetsuya; Ishii, Nobuyoshi; Fuma, Shoichi; Takeda, Hiroshi; Miyamoto, Kiriko; Yanagisawa, K.; Nakamura, Yuji [National Institute of Radiological Sciences, Inage, Chiba (Japan); Kawabata, Zenichiro [Center for Ecological Research, Kyoto Univ., Otsu, Shiga (Japan)

    2000-05-01

    This study explores a microorganic closed-ecosystem by computer simulation to illustrate symbiosis among populations in the microcosm that consists of heterotroph protozoa, Tetrahymena thermophila B as a consumer, autotroph algae, Euglena gracilis Z as a primary producer and saprotroph Bacteria, Escherichia coli DH5 as decomposer. The simulation program is written as a procedure of StarLogoT1.5.1, which is developed by Center for Connected Learning and Computer-Based Modeling, Tufts University. The virtual microcosm is structured and operated by the following rules; (1) Environment is defined as a lattice model, which consists of 10,201 square patches, 300 micron Wide, 300 micron Length and 100 micron Hight. (2) Each patch has its own attributes, Nutrient, Detritus and absolute coordinates, (3) Components of the species, Tetrahymena, Euglena and E-coli are defined as sub-system, and each sub-system has its own attributes as location, heading direction, cell-age, structured biomass, reserves energy and demographic parameters (assimilation rate, breeding threshold, growth rate, etc.). (4) Each component of the species, Tetrahymena, Euglena and E-coli, lives by foraging (Tetrahymena eats E-coli), excreting its metabolic products to the environment (as a substrate of E-coli), breeding and dying according vital condition. (5) Euglena utilizes sunlight energy by photosynthesis process and produces organic compounds. E-coli breaks down the organic compounds of dead protoplasm or metabolic wastes (Detritus) and releases inorganic substances to construct down stream of food cycle. Virtual ecosystem in this study is named SIM-COSM, a parallel computing model for self-sustaining system of complexity. It found that SIM-COSM is a valuable to illustrate symbiosis among populations in the microcosm, where a feedback mechanism acts in response to disturbances and interactions among species and environment. In the simulation, microbes increased demographic and environmental

  2. First toxicity data of chlorophenols on marine alga Dunaliella tertiolecta: correlation of marine algal toxicity with hydrophobicity and interspecies toxicity relationships.

    Science.gov (United States)

    Ertürk, M Doğa; Saçan, Melek Türker

    2012-05-01

    The toxicity of phenol and 13 chlorinated phenols to the marine alga Dunaliella tertiolecta is presented for the first time. The newly generated marine algal toxicity data was found to correlate strongly with the widely used hydrophobicity parameter-the logarithm of the n-octanol-water partition coefficient (log K(OW)). Interspecies relationships using the new marine algal toxicity data of chlorophenols with the previously published data on bacterium (Vibrio fischeri), protozoan (Tetrahymena pyriformis), daphnid (Daphnia magna), freshwater alga (Pseudokirchneriella subcapitata), and fish (Pimephales promelas) revealed promising results that could be exploited in extrapolations using freshwater data to predict marine algal toxicity. Copyright © 2012 SETAC.

  3. Structural variation of the ribosomal gene cluster within the class Insecta

    Energy Technology Data Exchange (ETDEWEB)

    Mukha, D.V.; Sidorenko, A.P.; Lazebnaya, I.V. [Vavilov Institute of General Genetics, Moscow (Russian Federation)] [and others

    1995-09-01

    General estimation of ribosomal DNA variation within the class Insecta is presented. It is shown that, using blot-hybridization, one can detect differences in the structure of the ribosomal gene cluster not only between genera within an order, but also between species within a genera, including sibling species. Structure of the ribosomal gene cluster of the Coccinellidae family (ladybirds) is analyzed. It is shown that cloned highly conservative regions of ribosomal DNA of Tetrahymena pyriformis can be used as probes for analyzing ribosomal genes in insects. 24 refs., 4 figs.

  4. All subgenomic mRNAs of equine arteritis virus contain a common leader sequence.

    OpenAIRE

    de Vries, A A; Chirnside, E D; Bredenbeek, P J; Gravestein, L A; Horzinek, M C; Spaan, W J

    1990-01-01

    During the replication of equine arteritis virus (EAV) six subgenomic mRNAs are synthesized. We present evidence that the viral mRNAs form a 3'-coterminal nested set and contain a common leader sequence of 208 nucleotides which is encoded by the 5'-end of the genome. The leader is joined to the bodies of mRNA 5 and 6 at positions defined by the sequence 5' UCAAC 3'. The part of the leader sequence flanking the UCAAC motif is very similar to the 5'-splice site of the Tetrahymena pre-rRNA. A po...

  5. Pseudomonas aeruginosa adaptation to lungs of cystic fibrosis patients leads to lowered resistance to phage and protist enemies

    DEFF Research Database (Denmark)

    Friman, Ville-Petri; Ghoul, Melanie; Molin, Søren

    2013-01-01

    ) patients affects its survival in the presence of natural phage (14/1, ΦKZ, PNM and PT7) and protist (Tetrahymena thermophila and Acanthamoebae polyphaga) enemies. We found that most of the bacteria isolated from relatively recently intermittently colonised patients (1-25 months), were innately phage......-resistant and highly toxic for protists. In contrast, bacteria isolated from long time chronically infected patients (2-23 years), were less efficient in both resisting phages and killing protists. Moreover, chronic isolates showed reduced killing of wax moth larvae (Galleria mellonella) probably due to weaker...... will likely slow down the emergence of beneficial resistance mutations....

  6. Analysis of expressed sequence tags (ESTs) and gene expression changes under different growth conditions for the ciliate Anophryoides haemophila, the causative agent of bumper car disease in the American lobster (Homarus americanus).

    Science.gov (United States)

    Acorn, Adam R; Clark, K Fraser; Jones, Sarah; Després, Béatrice M; Munro, Sarah; Cawthorn, Richard J; Greenwood, Spencer J

    2011-06-01

    The scuticociliate Anophryoides haemophila, causes bumper car disease in American lobster (Homarus americanus) in commercial holding facilities in Atlantic Canada. While the parasite has been recognized since the 1970s and much has been learned about its biology, minimal molecular characterization exists. With genome consortiums turning to model organisms like the ciliates Tetrahymena and Paramecium, the amount of relevant sequence data available has made sequence surveys more attractive for gene discovery in related ciliates. We sequenced 9984 expressed sequence tags (ESTs) from a non-normalized A. haemophila cDNA library to characterize gene expression patterns, functional gene distribution and to discover novel genes related to the parasitic life history. The A. haemophila ESTs were grouped into 843 clusters and singletons with 658 EST clusters having identifiable homologs, while 159 ESTs were unique and had no similarity to any sequences in the public databases. Not unexpectedly, about 67% of the A. haemophila ESTs have similarity to annotated and hypothetical genes from the related oligohymenophorean ciliate, Tetrahymena. Numerous cysteine proteases, hypothetical proteins and novel sequences possess putative secretory signal peptides suggesting that they may contribute to the pathogenesis of bumper car disease in lobster. Real time RT-qPCR analysis of cathepsin L and two homologs of cathepsin B did not show any changes in gene expression under varying in vitro growth conditions or during a modified-in vivo infection which may be suggestive of the opportunistic life history strategy of this ciliate. Copyright © 2011 Elsevier Inc. All rights reserved.

  7. Parasitic infections in mixed system-based heliciculture farms: dynamics and key epidemiological factors.

    Science.gov (United States)

    Segade, P; García-Estévez, J; Arias, C; Iglesias, R

    2013-04-01

    Heliciculture is an excellent alternative to obtain edible snails but its viability is seriously threatened by pathogens. A parasitological survey was conducted in 3 mixed system-based heliciculture farms in Galicia (NW Spain), with the species Tetrahymena rostrata, Tetrahymena limacis, Tetratrichomonas limacis, Cryptobia helicogenae, Brachylaima aspersae (metacercariae and sporocysts), Alloionema appendiculatum, Nemhelix bakeri, and Riccardoella limacum being commonly found infecting Helix aspersa aspersa (petit-gris) snails. With the exception of C. helicogenae, N. bakeri, and B. aspersae sporocysts, all species were also detected in Helix aspersa maxima (gros-gris) snails, although generally with lower parameters. Most monoxenous infections, and consequently multiple parasitism, exhibited a rising trend during the first 2 months of intensive mating, with tendencies being slowed down or even reversed during the third month as a result of accumulated mortality and a sampling-derived reduction in host density. No parasites were vertically transmitted and infections were initially acquired from invading gastropod and micromammal reservoirs during fattening. Finally, artificial hibernation reduced significantly the prevalence of most species. These results confirm the importance of parasites in heliciculture and emphasize the need to prevent the entry of wild reservoirs into the farms and to rapidly remove the carcasses of dead snails from the reproduction units and fattening pens.

  8. Catalysis of splicing-related reactions between dinucleotides by a ribozyme.

    Science.gov (United States)

    Kay, P S; Inoue, T

    Certain intervening sequence (IVS) RNAs catalyse their own excision from a primary transcript to yield mature RNA in a reaction termed self-splicing. These Group I IVS RNAs contain several conserved sequences and possess a common secondary structure. The Tetrahymena precursor ribosomal RNA possesses an IVS of this group that is known to self-splice in vitro. The nature of this IVS is of great interest to both biology and chemistry, because understanding its catalytic activity should shed new light on the function of RNA in biological systems and the evolution of RNA which might be relevant to the early stages of life on Earth. We have analysed the minimum requirement for this reaction as one approach to understanding the mechanism of this RNA catalysis. We now show that a fragment of the IVS RNA of Tetrahymena can mediate a simple transesterification reaction between the substrate GpN (where N is A, C, G or U) and the nucleophile CpU. This newly discovered reaction and its reverse reaction represent the fundamental catalytic activity of the self-splicing Group I IVSs.

  9. Teaching Phagocytosis Using Flow Cytometry

    Directory of Open Access Journals (Sweden)

    John Boothby

    2009-12-01

    Full Text Available Investigative microbiology on protists in a basic teaching laboratory environment is limited by student skill level, ease of microbial culture and manipulation, instrumentation, and time. The flow cytometer is gaining use as a mainstream instrument in research and clinical laboratories, but has had minimal application in teaching laboratories. Although the cost of a flow cytometer is currently prohibitive for many microbiology teaching environments and the number of trained instructors and teaching materials is limited, in many ways the flow cytometer is an ideal instrument for teaching basic microbiology. We report here on a laboratory module to study phagocytosis in Tetrahymena sp. using flow cytometry in a basic microbiology teaching laboratory. Students and instructors found the flow cytometry data analysis program, Paint-A-GatePRO-TM, to be very intuitive and easy to learn within a short period of time. Assessment of student learning about Tetrahymena sp., phagocytosis, flow cytometry, and investigative microbiology using an inquiry-based format demonstrated an overall positive response from students.

  10. Automated image analysis reveals the dynamic 3-dimensional organization of multi-ciliary arrays

    Directory of Open Access Journals (Sweden)

    Domenico F. Galati

    2016-01-01

    Full Text Available Multi-ciliated cells (MCCs use polarized fields of undulating cilia (ciliary array to produce fluid flow that is essential for many biological processes. Cilia are positioned by microtubule scaffolds called basal bodies (BBs that are arranged within a spatially complex 3-dimensional geometry (3D. Here, we develop a robust and automated computational image analysis routine to quantify 3D BB organization in the ciliate, Tetrahymena thermophila. Using this routine, we generate the first morphologically constrained 3D reconstructions of Tetrahymena cells and elucidate rules that govern the kinetics of MCC organization. We demonstrate the interplay between BB duplication and cell size expansion through the cell cycle. In mutant cells, we identify a potential BB surveillance mechanism that balances large gaps in BB spacing by increasing the frequency of closely spaced BBs in other regions of the cell. Finally, by taking advantage of a mutant predisposed to BB disorganization, we locate the spatial domains that are most prone to disorganization by environmental stimuli. Collectively, our analyses reveal the importance of quantitative image analysis to understand the principles that guide the 3D organization of MCCs.

  11. Structure of the parasites communities in two Erythrinidae fish from Amazon river system (Brazil

    Directory of Open Access Journals (Sweden)

    Natália Milhomem Alcântara

    Full Text Available This study compared the parasite communities of Hoplias malabaricus and Hoplerythrinus unitaeniatus from Amazon river system. Hoplias malabaricus were infected by Ichthyophthirius multifiliis, Piscinoodinium pillulare, Tetrahymena sp., Urocleidoides eremitus, Braga patagonica, metacercariae of Clinostomum marginatum, Procamallanus(Spirocamallanus inopinatus, larvae of Contracaecum sp. and larvae of Nomimoscolex matogrossensis. Hoplerythrinus unitaeniatus were also infected by these same species of protozoans, nematodes, digeneans and cestodes, except for Tetrahymena sp. and B. patagonica, which were replaced by Argulus pestifer, Urocleidoides sp., Whittingtonocotylecaetei, Whittingtonocotyle jeju and Gorytocephalus spectabilis. For both hosts, I. multifiliis and P. pillulare were the predominant parasites. Most of the parasites presented an overdispersion. Parasite species richness, Brillouin diversity, evenness and Berger-Parker dominance were similar for the two hosts. The length and weight of H. malabaricusshowed a positive correlation with the abundance of U. eremitusand Contracaecum sp., while the weight of H. unitaeniatus showed a positive correlation with the abundance of I. multifiliis. The diversity of ectoparasites seemed to be influenced by the behavior of these two hosts. This was shown by the similar parasite communities and was characterized by low species diversity, low evenness and low richness, and by a high prevalence of ectoparasites.

  12. Multiple genes of apparent algal origin suggest ciliates may once have been photosynthetic.

    Science.gov (United States)

    Reyes-Prieto, Adrian; Moustafa, Ahmed; Bhattacharya, Debashish

    2008-07-08

    Plantae (as defined by Cavalier-Smith, 1981) plastids evolved via primary endosymbiosis whereby a heterotrophic protist enslaved a photosynthetic cyanobacterium. This "primary" plastid spread into other eukaryotes via secondary endosymbiosis. An important but contentious theory in algal evolution is the chromalveolate hypothesis that posits chromists (cryptophytes, haptophytes, and stramenopiles) and alveolates (ciliates, apicomplexans, and dinoflagellates) share a common ancestor that contained a red-algal-derived "secondary" plastid. Under this view, the existence of several later-diverging plastid-lacking chromalveolates such as ciliates and oomycetes would be explained by plastid loss in these lineages. To test the idea of a photosynthetic ancestry for ciliates, we used the 27,446 predicted proteins from the macronuclear genome of Tetrahymena thermophila to query prokaryotic and eukaryotic genomes. We identified 16 proteins of possible algal origin in the ciliates Tetrahymena and Paramecium tetraurelia. Fourteen of these are present in other chromalveolates. Here we compare and contrast the likely scenarios for algal-gene origin in ciliates either via multiple rounds of horizontal gene transfer (HGT) from algal prey or symbionts, or through endosymbiotic gene transfer (EGT) during a putative photosynthetic phase in their evolution.

  13. Immediate dissemination of student discoveries to a model organism database enhances classroom-based research experiences.

    Science.gov (United States)

    Wiley, Emily A; Stover, Nicholas A

    2014-01-01

    Use of inquiry-based research modules in the classroom has soared over recent years, largely in response to national calls for teaching that provides experience with scientific processes and methodologies. To increase the visibility of in-class studies among interested researchers and to strengthen their impact on student learning, we have extended the typical model of inquiry-based labs to include a means for targeted dissemination of student-generated discoveries. This initiative required: 1) creating a set of research-based lab activities with the potential to yield results that a particular scientific community would find useful and 2) developing a means for immediate sharing of student-generated results. Working toward these goals, we designed guides for course-based research aimed to fulfill the need for functional annotation of the Tetrahymena thermophila genome, and developed an interactive Web database that links directly to the official Tetrahymena Genome Database for immediate, targeted dissemination of student discoveries. This combination of research via the course modules and the opportunity for students to immediately "publish" their novel results on a Web database actively used by outside scientists culminated in a motivational tool that enhanced students' efforts to engage the scientific process and pursue additional research opportunities beyond the course.

  14. Assessment of toxicity and mutagenicity in air particulate matter from an urban industrial area in the coast of the Rio de la Plata.

    Science.gov (United States)

    Müller, A; Alzuet, P; Herbarth, O; Ronco, A

    2001-01-01

    Chemical characterization and effects assessment of semivolatile organic compounds in organic extracts from air particulate matter from the region of the greater La Plata area was undertaken. Effects covered the study of mutagenicity with the Ames test (Salmonella typhimurium TA100 and TA98 strains with metabolic activation by S9) and cytotoxicity using the Tetrahymena pyriformis test system (growth rate, cell volume, and cell respiration). Chemical analysis of organic extracts was done using gas chromatography. Results demonstrate the presence of polycyclic aromatic hydrocarbons (PAH) in the matrix, high mutagenicity, and cytotoxicity. A higher mutagenic activity detected with TA98 and TA100 strains is associated with an increment of total PAH and total five or six ring PAH content, respectively. Linked with it, a PAH dependent toxicity on Tetrahymena pyriformis has been observed. This cell system proved to be very sensitive. From the results obtained with the cell respiration assay with T. pyriformis it appears that uncoupling agents are present in the samples. The results of this study indicate that air particulate matter from the Rio de La Plata area contains significant genotoxic and cytotoxic activity probably due to the presence of PAHs.

  15. Parasitic fauna of eight species of ornamental freshwater fish species from the middle Negro River in the Brazilian Amazon Region.

    Science.gov (United States)

    Tavares-Dias, Marcos; Lemos, Jefferson Raphael Gonzaga; Martins, Maurício Laterça

    2010-01-01

    Twenty-seven specimens of cardinal tetra Paracheirodon axelrodi, 33 rosy tetra Hyphessobrycon copelandi (Characidae), 28 marbled hatchetfish Carnegiella strigata, 26 blackwing hatchetfish Carnegiella martae (Gasteropelecidae), 27 bodó Ancistrus hoplogenys (Loricariidae), 31 brown pencilfish Nannostomus eques, 38 oneline pencilfish Nannostomus unifasciatus (Lebiasinidae) and 13 angelfish Pterophyllum scalare (Cichlidae) were collected from the middle Negro River, State of Amazonas, Brazil, for parasitological studies. Out of the total of 223 fish examined, 143 (64.1%) were parasitized by at least one parasite species. The highest prevalence rate was for Monogenea (36.7%), followed by Ichthyophthirius multifiliis (Ciliophora) (20.6%), Trichodina spp. (Ciliophora) (4.0%), Piscinoodinium pillulare (Dinoflagellida) (1.3%), Tetrahymena sp. (Ciliophora) (0.89%), and Procamallanus sp. (Nematoda) (0.4%). All eight fish species had Monogenea (Gyrodactylidae and Dactylogyridae) in the gills, but the highest prevalence occurred in P. scalare and the lowest in P. axelrodi and C. strigata. However, the highest mean intensity of Monogenea was found in P. scalare and A. hoplogenys. The protozoan I. multifiliis occurred in the six ornamental fish species examined, but C. strigata and C. martae had higher prevalence and mean intensity. Trichodina spp. were found only in the gills of C. strigata, C. martae and N. eques, and with higher mean intensity in C. strigata. On the other hand, the protozoan P. pilullare was found only in the gills of C. martae. This is the first report of Tetrahymena sp. in Brazil, and it occurred in the gills of C. strigata.

  16. A new bioassay with the yeast Saccharomyces cerevisiae on aquatoxic pollution; Ein neuer Biotest mit der Hefe Saccharomyces cerevisiae auf aquatische Toxizitaet

    Energy Technology Data Exchange (ETDEWEB)

    Weber, J.; Plantikow, A.; Kreutzmann, J. [NORDUM - Inst. fuer Umwelt und Analytik GmbH, Kessin/Rostock (Germany)

    2000-07-01

    The fermentation activity of the yeast Saccharomyces cerevisiae is used as a bioindicator to detect aquatoxic effects. This is done by measuring the CO{sub 2} production of yeast cells after a multiplication period affected by toxic substances. The concentration of toxicants diminishing the fermentation by 20% is taken as a characteristic value (EC{sub 20}). Organic compounds (unpolar and polar narcotics), inorganic salts (especially of heavy metals), surfactants and plant pesticides were tested. The results are compared so far as available with data of a ciliata assay using Tetrahymena pyriformis. A congruence of 90% and an equal sensibility of the assays resulted. The results of the yeast assay are therefore representative for ecotoxicological testing. The yeast assay is reproducible, easy to handle, and offers an alternative for sewage testing because sterile handling is not necessary. (orig.) [German] Die Gaerleistung der Hefe Saccharomyces cerevisiae wird als Bioindikator zur Erfassung aquatoxischer Wirkungen genutzt. Dazu wird die CO{sub 2}-Produktion der Hefezellen nach einer Vermehrungsphase unter toxischen Einfluessen gemessen. Als Kennwert (EC{sub 20}) dient die Schadstoffkonzentration, die die Gaerung um 20% mindert. Es werden organische Verbindungen (unpolare und polare Narkotika), anorganische Salze (insbesondere von Schwermetallen), Tenside und Pflanzenschutzmittel geprueft. Die Ergebnisse werden, soweit verfuegbar, mit den Daten eines Ciliatentestes mit Tetrahymena pyriformis verglichen. Es ergab sich eine Uebereinstimmung von 90% bei vergleichbarer Testempfindlichkeit. Ergebnisse des Hefetests sind damit oekotoxikologisch aussagefaehig. Der Test ist reproduzierbar, methodisch einfach zu handhaben und bietet eine Alternative fuer die Abwasserpruefung, da steriles Arbeiten nicht erforderlich ist. (orig.) The fermentation activity of the yeast Saccharomyces cerevisiae is used as a bioiondicator to detect aquatoxic effects. This is done by measuring the

  17. Entrapment of ciliates at the water-air interface.

    Directory of Open Access Journals (Sweden)

    Jonathan Ferracci

    Full Text Available The importance of water-air interfaces (WAI on microorganism activities has been recognized by many researchers. In this paper, we report a novel phenomenon: the entrapment of ciliates Tetrahymena at the WAI. We first characterized the behavior of cells at the interface and showed that the cells' swimming velocity was considerably reduced at the WAI. To verify the possible causes of the entrapment, we investigated the effects of positive chemotaxis for oxygen, negative geotaxis and surface properties. Even though the taxes were still effective, the entrapment phenomenon was not dependent on the physiological conditions, but was instead affected by the physical properties at the interface. This knowledge is useful for a better understanding of the physiology of microorganisms at interfaces in nature and in industry.

  18. Non-conventional expression systems for the production of vaccine proteins and immunotherapeutic molecules.

    Science.gov (United States)

    Legastelois, Isabelle; Buffin, Sophie; Peubez, Isabelle; Mignon, Charlotte; Sodoyer, Régis; Werle, Bettina

    2017-04-03

    The increasing demand for recombinant vaccine antigens or immunotherapeutic molecules calls into question the universality of current protein expression systems. Vaccine production can require relatively low amounts of expressed materials, but represents an extremely diverse category consisting of different target antigens with marked structural differences. In contrast, monoclonal antibodies, by definition share key molecular characteristics and require a production system capable of very large outputs, which drives the quest for highly efficient and cost-effective systems. In discussing expression systems, the primary assumption is that a universal production platform for vaccines and immunotherapeutics will unlikely exist. This review provides an overview of the evolution of traditional expression systems, including mammalian cells, yeast and E.coli, but also alternative systems such as other bacteria than E. coli, transgenic animals, insect cells, plants and microalgae, Tetrahymena thermophila, Leishmania tarentolae, filamentous fungi, cell free systems, and the incorporation of non-natural amino acids.

  19. Storage Stability and Improvement of Intermediate Moisture Foods, Phase 3

    Science.gov (United States)

    Labuza, T. P.

    1975-01-01

    Methods were determined for the improvement of shelf-life stability of intermediate moisture foods (IMF). Microbial challenge studies showed that protection against molds and Staphylococcus aureus could be achieved by a combination of antimicrobial agents, humectants and food acids. Potassium sorbate and propylene glycol gave the best results. It was also confirmed that the maximum in heat resistance shown by vegetative pathogens at intermediate water activities also occurred in a solid food. Glycols and sorbitol both achieve browning inhibition because of their action as a medium for reaction and effect on viscosity of the adsorbed phase. Chemical availability results showed rapid lysine loss before visual discoloration occurred. This is being confirmed with a biological test using Tetrahymena pyriformis W. Accelerated temperature tests show that effectiveness of food antioxidants against rancidity development can be predicted; however, the protection factor changes with temperature. BHA was found to be the best antioxidant for iron catalyzed oxidation.

  20. The ability to form full-length intron RNA circles is a general property of nuclear group I introns

    DEFF Research Database (Denmark)

    Nielsen, Henrik; Fiskaa, Tonje; Birgisdottir, Asa Birna

    2003-01-01

    In addition to splicing, group I intron RNA is capable of an alternative two-step processing pathway that results in the formation of full-length intron circular RNA. The circularization pathway is initiated by hydrolytic cleavage at the 3' splice site and followed by a transesterification reaction...... in which the intron terminal guanosine attacks the 5' splice site presented in a structure analogous to that of the first step of splicing. The products of the reactions are full-length circular intron and unligated exons. For this reason, the circularization reaction is to the benefit of the intron...... at the expense of the host. The circularization pathway has distinct structural requirements that differ from those of splicing and appears to be specifically suppressed in vivo. The ability to form full-length circles is found in all types of nuclear group I introns, including those from the Tetrahymena...

  1. Dicty_cDB: Contig-U13487-1 [Dicty_cDB

    Lifescience Database Archive (English)

    Full Text Available o rerio solute carrier family ... 63 5e-09 AE016879_1614( AE016879 |pid:none) Bacillus anthracis str. Ames, ... s... 46 0.44 4 ( DQ927303 ) Tetrahymena malaccensis strain MP75 mitochondrion... 40 0.44 4 ( AC174278 ) Medicago tr...-10 CU468135_2286( CU468135 |pid:none) Erwinia tasmaniensis strain ET1... 68 1e-10 CP001147_952( CP001147 |pid:non...pertussis strain 1... 49 9e-05 AF065159_25( AF065159 |pid:none) Bradyrhizobium japonicum ...e R3-3066P1, WO... 48 0.31 1 ( AE017355 ) Bacillus thuringiensis serovar konkukian str. 97-... 48 0.31 1

  2. Impacts of radiation exposure on the experimental microbial ecosystem: a particle-based model simulation approach

    Energy Technology Data Exchange (ETDEWEB)

    Doi, M.; Tanaka, N.; Fuma, S.; Kawabata, Z.

    2004-07-01

    Well-designed experimental model ecosystem could be a simple reference of the actual environment and complex ecological systems. For ecological toxicity test of radiation and other environmental toxicants, we investigated and aquatic microbial ecosystem (closed microcosm) in the test tube with initial substrates,autotroph flagellate algae (Euglena, G.), heterotroph ciliate protozoa (Tetrahymena T.) and saprotroph bacteria (E, coli). These species organizes by itself to construct the ecological system, that keeps the sustainable population dynamics for more than 2 years after inoculation only by adding light diurnally and controlling temperature at 25 degree Celsius. Objective of the study is to develop the particle-based computer simulation by reviewing interactions among microbes and environment, and analyze the ecological toxicities of radiation on the microcosm by replicating experimental results in the computer simulation. (Author) 14 refs.

  3. Calorific and carbon values of marine and freshwater Protozoa

    Science.gov (United States)

    Finlay, B. J.; Uhlig, G.

    1981-12-01

    Calorific and carbon values were determined for a variety of marine and freshwater Protozoa ( Noctiluca miliaris, Euplotes sp., Eufolliculina sp. respectively Tetrahymena pyriformis, Paramecium caudatum), their food sources (Bacteria, Dunaliella primolecta, Ceratium hirundinella), and for Protozoa-dominated plankton samples. Most calorific values lie close to the centre of the range covering organisms in general. Low values in some marine samples probably resulted from the retention of bound water in the dried material. When all results were combined with data selected from the literature, the dependence of calorific value on carbon content was highly significant. This relationship is probably also adequately described by an energy-carbon regression through the variety of organic compounds commonly found in organisms. Calorific value expressed per unit carbon is shown to vary little in Protozoa (mean conversion factor 46 J [mg C]-1) or throughout the range of biological materials considered in this study (45 J [mg C]-1).

  4. Identification and cloning of first cadmium metallothionein like gene from locally isolated ciliate, Paramecium sp.

    Science.gov (United States)

    Shuja, Rukhsana Nighat; Shakoori, Abdul Rauf

    2009-03-01

    First cadmium metallothionein like gene PMCd1 of a ciliate, Paramecium sp., isolated from industrial wastewater has been cloned and sequenced. PMCd1 is an intronless gene, encoding 612 nucleotides, with TAA coding for glutamine. The coding region of PMCd1 comprises 203 amino acids, including 37 cysteine residues with a conserved structural pattern in the form of recurring structural motifs, arranged in 17 x-cys-x-y-cys-x, 1 x-cys-cys-x and x-cys-x contexts. Both, the deduced amino acids and nucleotide sequence differ, not only from other animal metallothioneins (MTs), but also from the previously characterized Tetrahymena Cu and Cd-MTs. The translated protein of PMCd1 contains conserved cysteine residues, peculiar characteristic of stress inducible metallothionein genes of ciliates and other groups of organisms.

  5. Storage Stability and Improvement of Intermediate Moisture Foods

    Science.gov (United States)

    Labuza, T. P.

    1976-01-01

    Shelf life tests are used to estimate the rate of nonenzymatic browning; however, controlling the reducing sugar levels below 23:1 molar ratio to amines, slows the rate. In addition, liquid glycols surpress browning. The protozoan Tetrahymena pyriformis W can be used to estimate nutrition losses during browning. At high temperatures (80 to 120 C) used in processing intermediate moisture foods (IMF), vitamin C destruction shifts to a zero order mechanism. BHA and BHT are the most effective antioxidants against rancidity. In shelf life testing however, 45 C should be the maximum temperature used. Water binding agents are studied. The five isotherms of thirteen humectants were determined. The results show that neither the method of addition nor sequence of addition affects the a sub u lowering ability of these humectants. Results were used to formulate shelf stable IMF processed cheese foods with at least four months shelf life.

  6. Experimental evidence of false-positive Comet test results due to TiO2 particle--assay interactions.

    Science.gov (United States)

    Rajapakse, Katarina; Drobne, Damjana; Kastelec, Damijana; Marinsek-Logar, Romana

    2013-08-01

    We have studied the genotoxicity of TiO2 particles with a Comet assay on a unicellular organism, Tetrahymena thermophila. Exposure to bulk- or nano-TiO2 of free cells, cells embedded in gel or nuclei embedded in gel, all resulted in a positive Comet assay result but this outcome could not be confirmed by cytotoxicity measures such as lipid peroxidation, elevated reactive oxygen species or cell membrane composition. Published reports state that in the absence of cytotoxicity, nano- and bulk-TiO2 genotoxicity do not occur directly, and a possible explanation of our Comet assay results is that they are false positives resulting from post festum exposure interactions between particles and DNA. We suggest that before Comet assay is used for nanoparticle genotoxicity testing, evidence for the possibility of post festum exposure interactions should be considered. The acellular Comet test described in this report can be used for this purpose.

  7. Use of a Fluorescent Aptamer RNA as an Exonic Sequence to Analyze Self-Splicing Ability of a Group I Intron from Structured RNAs

    Directory of Open Access Journals (Sweden)

    Airi Furukawa

    2016-11-01

    Full Text Available Group I self-splicing intron constitutes an important class of functional RNA molecules that can promote chemical transformation. Although the fundamental mechanism of the auto-excision from its precursor RNA has been established, convenient assay systems for its splicing activity are still useful for a further understanding of its detailed mechanism and of its application. Because some host RNA sequences, to which group I introns inserted form stable three-dimensional (3D structures, the effects of the 3D structures of exonic elements on the splicing efficiency of group I introns are important but not a fully investigated issue. We developed an assay system for group I intron self-splicing by employing a fluorescent aptamer RNA (spinach RNA as a model exonic sequence inserted by the Tetrahymena group I intron. We investigated self-splicing of the intron from spinach RNA, serving as a model exonic sequence with a 3D structure.

  8. Parasitic fauna of eight species of ornamental freshwater fish species from the middle Negro River in the Brazilian Amazon Region Fauna parasitária de oito espécies de peixes ornamentais de água doce do médio Rio Negro na Amazônia brasileira

    Directory of Open Access Journals (Sweden)

    Marcos Tavares-Dias

    2010-06-01

    Full Text Available Twenty-seven specimens of cardinal tetra Paracheirodon axelrodi, 33 rosy tetra Hyphessobrycon copelandi (Characidae, 28 marbled hatchetfish Carnegiella strigata, 26 blackwing hatchetfish Carnegiella martae (Gasteropelecidae, 27 bodó Ancistrus hoplogenys (Loricariidae, 31 brown pencilfish Nannostomus eques, 38 oneline pencilfish Nannostomus unifasciatus (Lebiasinidae and 13 angelfish Pterophyllum scalare (Cichlidae were collected from the middle Negro River, State of Amazonas, Brazil, for parasitological studies. Out of the total of 223 fish examined, 143 (64.1% were parasitized by at least one parasite species. The highest prevalence rate was for Monogenea (36.7%, followed by Ichthyophthirius multifiliis (Ciliophora (20.6%, Trichodina spp. (Ciliophora (4.0%, Piscinoodinium pillulare (Dinoflagellida (1.3%, Tetrahymena sp. (Ciliophora (0.89%, and Procamallanus sp. (Nematoda (0.4%. All eight fish species had Monogenea (Gyrodactylidae and Dactylogyridae in the gills, but the highest prevalence occurred in P. scalare and the lowest in P. axelrodi and C. strigata. However, the highest mean intensity of Monogenea was found in P. scalare and A. hoplogenys. The protozoan I. multifiliis occurred in the six ornamental fish species examined, but C. strigata and C. martae had higher prevalence and mean intensity. Trichodina spp. were found only in the gills of C. strigata, C. martae and N. eques, and with higher mean intensity in C. strigata. On the other hand, the protozoan P. pilullare was found only in the gills of C. martae. This is the first report of Tetrahymena sp. in Brazil, and it occurred in the gills of C. strigata.Para estudos parasitológicos, 27 espécimes de cardinal Paracheirodon axelrodi, 33 rosa-céu Hyphessobrycon copelandi (Characidae, 28 peixes borboleta Carnegiella strigata e 26 Carnegiella martae (Gasteropelecidae, 27 bodó ou cascudo Ancistrus hoplogenys (Loricariidae, 31 peixes-lápis Nannostomus eques e 38 Nannostomus unifasciatus

  9. Heavy metal whole-cell biosensors using eukaryotic microorganisms: an updated critical review.

    Directory of Open Access Journals (Sweden)

    Juan-Carlos eGutierrez

    2015-02-01

    Full Text Available This review analyzes the advantages and disadvantages of using eukaryotic microorganisms to design whole-cell biosensors (WCBs for monitoring environmental heavy metal pollution in soil or aquatic habitats. Basic considerations for designing an eukaryotic WCB are also shown. A comparative analysis of the promoter genes used to design whole-cell biosensors is carried out, and the sensitivity and reproducibility of the main reporter genes used is also reviewed. Three main eukaryotic taxonomic groups are considered: yeasts, microalgae and ciliated protozoa. Models that have been widely analyzed as potential WCBs are the Saccharomyces cerevisiae model among yeasts, the Tetrahymena thermophila model for ciliates and Chlamydomonas model for microalgae. The advantages and disadvantages of each microbial group are discussed, and a ranking of sensitivity to the same type of metal pollutant from reported eukaryotic WCBs is also shown. General conclusions and possible future developments of eukaryotic WCBs are reported.

  10. Investigations onboard the biosatellite Cosmos-1667

    Science.gov (United States)

    Gazenko, O. G.; Ilyin, E. A.

    The program of the 7-day flight of the biosatellite Cosmos-1667 launched in July 1985 included experiments on two rhesus monkeys, ten Wistar SPF rats, ten newts, Drosophila flies, maize seedlings, lettuce sprouts, and unicellular organisms - Tetrahymena. The primate study demonstrated that transition to orbital flight was accompanied by a greater excitability of the vestibular apparatus and an increased linear blood flow velocity in the common carotid artery. The rat studies showed that atrophy of antigravity muscles and osteoporosis of limb bones developed even during short-term exposure to microgravity. The experiments on other living systems revealed no microgravity effects on the cell division rate, proliferative activity of cells of regenerating tissues and organs, energy metabolism of developing insects, structure or chemical composition of higher plant seedlings.

  11. A Two-Piece Derivative of a Group I Intron RNA as a Platform for Designing Self-Assembling RNA Templates to Promote Peptide Ligation

    Directory of Open Access Journals (Sweden)

    Takahiro Tanaka

    2012-01-01

    Full Text Available Multicomponent RNA-peptide complexes are attractive from the viewpoint of artificial design of functional biomacromolecular systems. We have developed self-folding and self-assembling RNAs that serve as templates to assist chemical ligation between two reactive peptides with RNA-binding capabilities. The design principle of previous templates, however, can be applied only to limited classes of RNA-binding peptides. In this study, we employed a two-piece derivative of a group I intron RNA from the Tetrahymena large subunit ribosomal RNA (LSU rRNA as a platform for new template RNAs. In this group I intron-based self-assembling platform, modules for the recognition of substrate peptides can be installed independently from modules holding the platform structure. The new self-assembling platform allows us to expand the repertoire of substrate peptides in template RNA design.

  12. A ciliate memorizes the geometry of a swimming arena

    Science.gov (United States)

    Kunita, Itsuki; Yamaguchi, Tatsuya; Tero, Atsushi; Akiyama, Masakazu; Kuroda, Shigeru; Nakagaki, Toshiyuki

    2016-01-01

    Previous studies on adaptive behaviour in single-celled organisms have given hints to the origin of their memorizing capacity. Here we report evidence that a protozoan ciliate Tetrahymena has the capacity to learn the shape and size of its swimming space. Cells confined in a small water droplet for a short period were found to recapitulate circular swimming trajectories upon release. The diameter of the circular trajectories and their duration reflected the size of the droplet and the period of confinement. We suggest a possible mechanism for this adaptive behaviour based on a Ca2+ channel. In our model, repeated collisions with the walls of a confining droplet result in a slow rise in intracellular calcium that leads to a long-term increase in the reversal frequency of the ciliary beat. PMID:27226383

  13. AcEST: DK957923 [AcEST

    Lifescience Database Archive (English)

    Full Text Available onema denti... 127 3e-29 sp|Q5L5L0|SYI_CHLAB Isoleucyl-tRNA synthetase OS=Chlamydophila a... 127 3e-29 sp|Q8...22L8|SYI_CHLCV Isoleucyl-tRNA synthetase OS=Chlamydophila c... 126 9e-29 sp|Q65ZU1|SYI_BORGA Isoleucyl-tRNA ...(73%) Frame = +1 Query: 238 KDFNFPLQKEKVLALWKRLDAFKRQLELSEGKPEYIFYDGPPFATGLPHCGHILAGTIKD 417 ++ NFP ++EK+L W... + F+ L+ S+ KP++ FYDGPPFATGLPH GHILAGTIKD Sbjct: 11 ENINFPAEEEKILEFWTEFNCFQECLKQSKHKPKFTFYDGPPFATGLPHYGHILAG...sp|P36422|SYI_TETTH Isoleucyl-tRNA synthetase OS=Tetrahymena thermophila GN=ILSA PE=3 SV=1 Length = 1081 Sco

  14. [The activity of complement system in children with autistic spectrum disorders].

    Science.gov (United States)

    Cheremnykh, E G; Karpova, N S; Factor, M I; Shushpanova, O V; Simashkova, N V; Brusov, O S

    To evaluate the state of complement system (CS) activity in children with autistic spectrum disorders (ASD) and children with schizophrenia on the basis of development and implementation of a new method of CS determination. A study included 249 patients, aged from 3 to 14 years. The control group consisted of 279 age-matched children. The authors developed a method for integral evaluation of CS activity based on the changes in the death of free swimming ciliata Tetrahymena pyriformis measured with the apparatus BioLat (Moscow, Russia). The integral CS activity (T50) was estimated as the time of death of 50% of ciliata in the blood serum (serum concentration was 5%). A comparative analysis of CS activity showed statistical differences in median T50 values between patients and controls (pautism group and children schizophrenia group were identified (p<0.005). The CS activity was lower in patients with ASD compared to children with schizophrenia.

  15. IFT trains in different stages of assembly queue at the ciliary base for consecutive release into the cilium.

    Science.gov (United States)

    Wingfield, Jenna L; Mengoni, Ilaria; Bomberger, Heather; Jiang, Yu-Yang; Walsh, Jonathon D; Brown, Jason M; Picariello, Tyler; Cochran, Deborah A; Zhu, Bing; Pan, Junmin; Eggenschwiler, Jonathan; Gaertig, Jacek; Witman, George B; Kner, Peter; Lechtreck, Karl

    2017-05-31

    Intraflagellar transport (IFT) trains, multimegadalton assemblies of IFT proteins and motors, traffic proteins in cilia. To study how trains assemble, we employed fluorescence protein-tagged IFT proteins in Chlamydomonas reinhardtii. IFT-A and motor proteins are recruited from the cell body to the basal body pool, assembled into trains, move through the cilium, and disperse back into the cell body. In contrast to this 'open' system, IFT-B proteins from retrograde trains reenter the pool and a portion is reused directly in anterograde trains indicating a 'semi-open' system. Similar IFT systems were also observed in Tetrahymena thermophila and IMCD3 cells. FRAP analysis indicated that IFT proteins and motors of a given train are sequentially recruited to the basal bodies. IFT dynein and tubulin cargoes are loaded briefly before the trains depart. We conclude that the pool contains IFT trains in multiple stages of assembly queuing for successive release into the cilium upon completion.

  16. Histopathological study on parasites in freshwater ornamental fishes in Iran.

    Science.gov (United States)

    Nematollahi, A; Jaberi, S; Helan, J Ashrafi; Sheikhzadeh, N

    2016-09-01

    During March 2012 through February 2013, 100 freshwater ornamental fishes in 22 species from some aquarium fish shops were examined. Specimens were dissected and tissue samples consisted of liver, kidney, spleen, heart, intestine, ovary, brain and eye were fixed in 10 % buffered formalin and sections were provided and stained with hematoxylin and eosin, Periodic Acid-Schiff, Giemsa and acid-fast staining (Ziehl-Neelsen). At present study six species of protozoans consisting of Eimeria spp. Cryptosporidium spp., Tetrahymena corlissi, Thecamoeba spp., Giardia spp., Myxobolus spp. and two metazoan parasite consisting of Nematoda spp. and Benedenia monticelli were identified. Thecamoeba, B. monticelli and Cryptosporidium spp. were not reported in previous Iranian studies and it is the first report of infestation to this parasite in ornamental fish in Iran.

  17. Function of nuclear membrane proteins in shaping the nuclear envelope integrity during closed mitosis.

    Science.gov (United States)

    Yang, Hui-Ju; Iwamoto, Masaaki; Hiraoka, Yasushi; Haraguchi, Tokuko

    2017-06-01

    The nuclear envelope (NE) not only protects the genome from being directly accessed by detrimental agents but also regulates genome organization. Breaches in NE integrity threaten genome stability and impede cellular function. Nonetheless, the NE constantly remodels, and NE integrity is endangered in dividing or differentiating cells. Specifically, in unicellular eukaryotes undergoing closed mitosis, the NE expands instead of breaking down during chromosome segregation. The newly assembling nuclear pore complexes (NPCs) penetrate the existing NE in interphase. A peculiar example of NE remodelling during nuclear differentiation in Tetrahymena involves formation of the redundant NE and clustered NPCs. Even under these conditions, the NE remains intact. Many recent studies on unicellular organisms have revealed that nuclear membrane proteins, such as LEM-domain proteins, play a role in maintaining NE integrity. This review summarizes and discusses how nuclear membrane proteins participate in NE integrity. © The Authors 2017. Published by Oxford University Press on behalf of the Japanese Biochemical Society. All rights reserved.

  18. Toxicity of acid mine pit lake water remediated with limestone and phosphorus

    Energy Technology Data Exchange (ETDEWEB)

    Neil, L.L.; McCullough, C.D.; Lund, M.A.; Evans, L.H.; Tsvetnenko, Y. [Edith Cowan University, Joondalup, WA (Australia)

    2009-11-15

    Pit lakes are increasingly common worldwide and have potential to provide many benefits. However, lake water toxicity may require remediation before beneficial end uses can be realised. Three treatments to remediate AMD (pH similar to 4.8) pit lake water containing elevated concentrations of Al and Zn from Collie, Western Australia were tested in mesocosms. Treatments were: (a) limestone neutralisation (L), (b) phosphorus amendment (P), and c) combined limestone neutralisation and phosphorus amendment (L+P). Laboratory bioassays with Ceriodaphnia cf. dubia, Chlorella protothecoides and Tetrahymena thermophila assessed remediation. Limestone neutralisation increased pH and reduced heavy metal concentrations by 98% (Al) to 14% (Mg), removing toxicity to the three test species within 2 months. Phosphorus amendment removed toxicity after 6 months of treatment. However, phosphorus amendment to prior limestone neutralisation failed to reduce toxicity more than limestone neutralisation alone. Low concentrations of both phosphorus and nitrogen appear to limit phytoplankton population growth in all treatments.

  19. Alternate solution to a discrete car parking problem

    Science.gov (United States)

    Texter, John

    1989-11-01

    A few years ago, P. J. Flory [J. Am. Chem. Soc. 61, 1518 (1939)] solved a statistical problem analogous to determining the random-irreversible saturation formation of a 1×2 overlayer on a linear n lattice, by deriving an expression for the fraction of empty lattice points. Methods are presented here for both the enumeration and construction of saturation configurations. This alternate approach is derived from the theory of partitions and incorporates shift and sum-rule operators for the calculation of configurational probabilities. The fraction of filled lattice points is evaluated, and the configurational probabilities provide distribution functions for saturation configurations having different saturation levels (for fixed n). These distribution functions can be used to calculate sequence selective properties in addition to average saturation levels. Applications are illustrated in the analysis of the randomness of dehydrochlorination of polyvinylchloride and the distribution of UV-induced cyclobutyl-thymine dimers in Tetrahymena pyriformis DNA.

  20. Biopartitioning micellar chromatography: an alternative high-throughput method for assessing the ecotoxicity of anilines and phenols.

    Science.gov (United States)

    Bermúdez-Saldaña, J M; Escuder-Gilabert, L; Medina-Hernández, M J; Villanueva-Camañas, R M; Sagrado, S

    2007-06-01

    An investigation of the use of the chromatographic retention (log k) as an in vitro approach for modelling the toxicity to Fathead Minnows of anilines and phenols is developed. A data set of 65 compounds with available experimental toxicity data was used. Log k data at three pH values were used for the compounds classification and two groups or 'MODEs' were identified. For one 'MODE' a quantitative retention-activity relationship (QRAR) model was calculated. Finally, it was used to estimate the toxicity to Fathead minnows of anilines and phenols for which experimental data are not available. These estimations were compared to those obtained from another toxicity (to Tetrahymena pyriformis) data set and those estimated from a U.S. EPA QSAR approach (ECOSAR software) to decide on the toxicity level according to the Directive 3/21/EEC.

  1. Empirical demonstration of environmental sensing in catalytic RNA: evolution of interpretive behavior at the origins of life.

    Science.gov (United States)

    Lehman, Niles; Bernhard, Tess; Larson, Brian C; Robinson, Andrew J N; Southgate, Christopher C B

    2014-12-04

    The origins of life on the Earth required chemical entities to interact with their environments in ways that could respond to natural selection. The concept of interpretation, where biotic entities use signs in their environment as proxy for the existence of other items of selective value in their environment, has been proposed on theoretical grounds to be relevant to the origins and early evolution of life. However this concept has not been demonstrated empirically. Here, we present data that certain catalytic RNA sequences have properties that would enable interpretation of divalent cation levels in their environment. By assaying the responsiveness of two variants of the Tetrahymena ribozyme to the Ca(2+) ion as a sign for the more catalytically useful Mg(2+) ion, we show an empirical proof-of-principle that interpretation can be an evolvable trait in RNA, often suggested as a model system for early life. In particular we demonstrate that in vitro, the wild-type version of the Tetrahymena ribozyme is not interpretive, in that it cannot use Ca(2+) as a sign for Mg(2+). Yet a variant of this sequence containing five mutations that alter its ability to utilize the Ca(2+) ion engenders a strong interpretive characteristic in this RNA. We have shown that RNA molecules in a test tube can meet the minimum criteria for the evolution of interpretive behaviour in regards to their responses to divalent metal ion concentrations in their environment. Interpretation in RNA molecules provides a property entirely dependent on natural physico-chemical interactions, but capable of shaping the evolutionary trajectory of macromolecules, especially in the earliest stages of life's history.

  2. Verification of epigenetic inheritance in a unicellular model system: multigenerational effects of hormonal imprinting.

    Science.gov (United States)

    Kőhidai, László; Lajkó, Eszter; Pállinger, Eva; Csaba, György

    2012-10-01

    The unicellular Tetrahymena has receptors for hormones of higher vertebrates, produces these hormones, and their signal pathways are similar. The first encounter with a hormone in higher dose provokes the phenomenon of hormonal imprinting, by which the reaction of the cell is quantitatively modified. This modification is transmitted to the progeny generations. The duration of the single imprinter effect of two representative signal molecules, insulin and 5-HT (5-hydroxytryptamine), in two concentrations (10(-6) and 10(-15) M) were studied. The effects of imprinting were followed in 5 physiological indices: (i) insulin binding, (ii) 5-HT synthesis, (iii) swimming behaviour, (iv) cell growth and (v) chemotaxis in progeny generations 500 and 1000. The result of each index was different from the non-imprinted control functions, growth rate, swimming behaviour and chemotactic activity to insulin being enhanced, while others, e.g. synthesis and chemotactic responsiveness of 5-HT and the binding of insulin were reduced. This means that a function-specific heritable epigenetic change during imprinting occurs, and generally a single encounter with a femtomolar hormone concentration is enough for provoking durable and heritable imprinting in Tetrahymena. The experiments demonstrate the possibility of epigenetic effects at a unicellular level and call attention to the possibility that the character of unicellular organisms has changed through to the present day due to an enormous amount of non-physiological imprinter substances in their environment. The results - together with results obtained earlier in mammals - point to the validity of epigenetic imprinting effects throughout the animal world.

  3. Mating of the stichotrichous ciliate Oxytricha trifallax induces production of a class of 27 nt small RNAs derived from the parental macronucleus.

    Directory of Open Access Journals (Sweden)

    Alan M Zahler

    Full Text Available Ciliated protozoans possess two types of nuclei; a transcriptionally silent micronucleus, which serves as the germ line nucleus, and a transcriptionally active macronucleus, which serves as the somatic nucleus. The macronucleus is derived from a new diploid micronucleus after mating, with epigenetic information contributed by the parental macronucleus serving to guide the formation of the new macronucleus. In the stichotrichous ciliate Oxytricha trifallax, the macronuclear DNA is highly processed to yield gene-sized nanochromosomes with telomeres at each end. Here we report that soon after mating of Oxytricha trifallax, abundant 27 nt small RNAs are produced that are not present prior to mating. We performed next generation sequencing of Oxytricha small RNAs from vegetative and mating cells. Using sequence comparisons between macronuclear and micronuclear versions of genes, we found that the 27 nt RNA class derives from the parental macronucleus, not the developing macronucleus. These small RNAs are produced equally from both strands of macronuclear nanochromosomes, but in a highly non-uniform distribution along the length of the nanochromosome, and with a particular depletion in the 30 nt telomere-proximal positions. This production of small RNAs from the parental macronucleus during macronuclear development stands in contrast to the mechanism of epigenetic control in the distantly related ciliate Tetrahymena. In that species, 28-29 nt scanRNAs are produced from the micronucleus and these micronuclear-derived RNAs serve as epigenetic controllers of macronuclear development. Unlike the Tetrahymena scanRNAs, the Oxytricha macronuclear-derived 27 mers are not modified by 2'O-methylation at their 3' ends. We propose models for the role of these "27macRNAs" in macronuclear development.

  4. CeO2 nanoparticles alter the outcome of species interactions.

    Science.gov (United States)

    Peng, Cheng; Chen, Ying; Pu, Zhichao; Zhao, Qing; Tong, Xin; Chen, Yongsheng; Jiang, Lin

    2017-06-01

    Despite considerable research on the environmental impacts of nanomaterials, we know little about how they influence interactions between species. Here, we investigated the acute (12 d) and chronic (64 d) toxicities of cerium oxide nanoparticles (CeO2 NPs) and bulk particles (0-200 mg/L) to three ciliated protist species (Loxocephalus sp., Paramecium aurelia, and Tetrahymena pyriformis) in single-, bi-, and multispecies microcosms. The results show that CeO2 NPs strongly affected the interactions between ciliated protozoan species. When exposed to the highest CeO2 NPs (200 mg/L), the intrinsic growth rates of Loxocephalus and Paramecium were significantly decreased by 18.87% and 88.27%, respectively, while their carrying capacities declined by more than 90%. However, CeO2 NP exposure made it difficult to predict outcomes of interspecific competition between species. At higher NP exposure (100 and 200 mg/L), competition led to the extinction of both species in the Loxocephalus and Paramecium microcosms that survived in the absence of competitors or CeO2 NPs. Further, the presence of potential competitors improved the survival of Loxocephalus to hundreds of individuals per milliliter in microcosms with Tetrahymena where Loxocephalus would otherwise not be able to tolerate high levels of NP exposure. This result could be attributed to weakened NP adsorption on the cell surface due to competitor-caused reduction of NP surface charge (from -18.52 to -25.17 mV) and intensified NP aggregation via phagocytosis of NPs by ciliate cells. Our results emphasize the need to explicitly consider species interactions for a more comprehensive understanding of the ecological consequences of NP exposure.

  5. A novel role of centrin in flagellar motility: stabilizing an inner-arm dynein motor in the flagellar axoneme

    Directory of Open Access Journals (Sweden)

    Ziyin Li

    2014-07-01

    Full Text Available Centrin is an evolutionarily conserved EF-hand calcium-binding protein found in the centriole of animals and the basal body of flagellated organisms. It was originally discovered in the flagellated unicellular green alga Chlamydomonas reinhardtii, where it associates with flagellum-associated structures and regulates basal body duplication and flagellar motility. Centrin constitutes a light chain of three inner-arm dynein complexes in the flagellar axoneme in Chlamydomonas, and presumably regulates the activity of the inner-arm dynein for flagellar motility. In the ciliated organism Tetrahymena, centrin also associates with the inner-arm dynein and appears to regulate the microtubule sliding velocity of the inner-arm dynein. Using Trypanosoma brucei as the model organism, we discovered that centrin maintains the stability of an inner-arm dynein in the flagellar axoneme [Wei et al., (2014 Nat. Commun 5: 4060]. T. brucei expresses five centrins, three of which, TbCentrin1, 2, and 4, associate with the flagellar basal body, but no centrin was found to regulate cell motility. We found that TbCentrin3 associates tightly with the flagellum and that RNAi of TbCentrin3 compromised cell motility. Biochemical approaches further showed that TbCentrin3 interacts with TbIAD5-1, an inner-arm dynein in the flagellar axoneme. Knockdown of TbIAD5-1 also caused defective cell motility. Strikingly, depletion of TbCentrin3 or depletion of TbIAD5-1 resulted in disassembly of the complex from the axoneme and subsequent degradation of the complex in the cytosol. Our findings identified a novel role of TbCentrin3 in cell motility by stabilizing TbIAD5-1 in the axoneme, which likely is well conserved in other flagellated and ciliated organisms, such as Chlamydomonas and Tetrahymena where centrin is also known to associate with inner-arm dyneins.

  6. A simplified experimental model for clearance of some pathogenic bacteria using common bacterivorous ciliated spp. in Tigris river

    Science.gov (United States)

    Ali, Talib Hassan; Saleh, Dhuha Saad

    2014-03-01

    Bacteria-specific uptake rates of three different protozoan taxa on a pure and mixed bacterial community was studied by means of a simplified and functionally reproducible experimental model. The bacterial species Shigella flexneri, Escherichia coli and Salmonella typhi were isolated and classified from stool samples of patients suffering from diarrhea. Paramecium caudatum, Tetrahymena pyriformis and Halteria grandinella, free living ciliate Protozoans, were isolated and identified from Tigris river water. Pure and mixed ( E. coli + S. typhi), ( E. coli + Sh. flexneri) bacterial cultures were used with each ciliate genera to evaluate the following: predator duplication rate, prey reduction rate, clearance rate and net grazing rate. We used selective lactose fermentation phenomena of enteric bacteria on MacConkey medium for the quantification of bacteria cultural characteristics. The final bacteria concentration was reduced by growing protozoa of 98-99.9 % compared to protozoa-free controls. It showed that Tetrahymena pyriformis had the highest duplication rate (4.13 time/day) in both types of cultures (pure and mixed), followed by Paramecium caudatum and Halteria grandinella, respectively. Paramecium caudatum had the highest rate of ingestion in both types of cultures (26 × 103 bacteria/organism/hr) and yielded the longest time required for 90 % bacterial reduction in a pure suspension of S. typhi (166 h). Clearance rates of pathogenic bacteria by ciliates ranged between 106 nanoliter/organism/h by P. caudatum to S. typhi and 1.92 nanoliter/organism/h seen in T. pyriformis in ( E. coli + S. typhi) mixed culture. We used aquatic experimental microcosms under controlled conditions to explore bacteria-dependent ciliate growth and examined whether these ciliates could discriminate between equally sized bacterial preys in a mixture.

  7. A NEW METHOD TO ASSESS FUNCTIONAL ACTIVITY OF SERUM COMPLEMENT SYSTEM

    Directory of Open Access Journals (Sweden)

    E. G. Cheremnykh

    2015-01-01

    Full Text Available Complement system is an important component of innate immunity, providing primary protection against pathogens invading the body. In addition, it was shown that the complement system is associated with many diseases, not only autoimmune and infectious, but also mental disorders. In this regard, it is necessary to develop affordable and fast method of measuring activity of the complement system in real-time mode. We present a new semi-automated method for assessment of serum complement activity. The assay is based on cytolytic action of complement system upon the ciliate organism Tetrahymena pyriformis. This method consists in repeated counting of live Tetrahymena motile cells by means of specially developed Biolat device, which consists of two video cameras, light sources, and movable round plate. The plate has two rows of holes. The device also includes microprocessor control unit based on AutoCiliata software, intended for control of operation module and counting the surviving cell. The calculations are based on fixation of two sequential video-frames, with subsequent software image processing. Cell death events were observed upon incubation in triethanolamine (TEA buffer containing 5% of blood serum. We have also compared complement activity in different buffers, i.e., standard medium for culturing of ciliates, Veronal-Medinalum buffer, and the TEA buffer. TEA buffer was found superior to the Veronal buffer when applied in the test system. The time of cell death in the TEA-buffered medium containing 5% serum was < 15 minutes for all the sera studied. The parameters denoting serum complement activity were as follows: a half-life time for the moving cells (TLD50, and a similar value for 100% cell inactivation (1/TLD50, functional activity of the complement system, ACS. The sensitivity of this assay was calculated from dependencies between TLD50 and ACS, and actual serum concentrations. We have suggested an opportunity for evaluation of an

  8. Biotest- and chemistry-based hazard assessment of soils, sediments and solid wastes

    Energy Technology Data Exchange (ETDEWEB)

    Pollumaa, L.; Kahru, A. [National Inst. of Chemical Physics and Biophysics, Tallinn (Estonia); Manusadzianas, L. [Inst. of Botany, Vilnius (Lithuania)

    2004-07-01

    The aim of the current study was (1) to compare the ecotoxicity and chemistry-based environmental evaluations for 27 solid-phase environmental samples (soils, sediments, solid wastes); (2) to suggest the battery of biotests for the screening of water-extracted toxicity. 14 soils, 9 sediments and 4 oil-shale industry solid waste samples from Estonia and Lithuania were analyzed for the concentration of total PAHs, heavy metals, oil products and water-extracted phenols. The pollution level was evaluated by comparison of measured concentrations with Estonian permitted limit values in residential (PLV{sub r}) and industrial (PLV{sub i}) areas for each key pollutant. A battery of 8 aquatic toxicity tests was applied for the analysis of aqueous extracts (L/S=3) of samples: tests with microalgae Selenastrum capricornutum, macroalgae Nitellopsis obtusa, protozoa Tetrahymena thermophila, crustaceans Daphnia magna and Thamnocephalus platyurus, rotifers Brachionus calyciflorus and photobacteria Vibrio fischeri. Particle-bound bioavailable toxicity was evaluated using a kinetic photobacterial assay with Vibrio fischeri (Solid-Phase Flash-Assay). The toxicity data were evaluated by MaxTox index (highest toxic signal of the battery). Results. Chemical evaluation and toxicological evaluation pointed to the same direction in half of the cases (13/27): 5 samples (including 2 presumably clean control soils) proved harmless and 8 hazardous to environment in case of both evaluations. However, there was a disagreement between chemical and toxicological evaluations for the rest of the samples (14/27). In two mismatching cases (soils from the territory of former gasoline stations) the level of oil products exceeded the PLV{sub r}, but no toxicity was detected, most probably due to the low bioavailability of aged pollutants. The results of this study show the necessity of biotesting in environmental risk assessment to avoid the falsenegative results that may result in harmful effects for

  9. Acute toxicity of metals and reference toxicants to a freshwater ostracod, Cypris subglobosa Sowerby, 1840 and correlation to EC{sub 50} values of other test models

    Energy Technology Data Exchange (ETDEWEB)

    Khangarot, B.S., E-mail: bkhangarot@hotmail.com [Ecotoxicology Division, Indian Institute of Toxicology Research (Formerly: Industrial Toxicology Research Centre), Post Box No. 80, Mahatma Gandhi Marg, Lucknow 226001 (India); Das, Sangita [Ecotoxicology Division, Indian Institute of Toxicology Research (Formerly: Industrial Toxicology Research Centre), Post Box No. 80, Mahatma Gandhi Marg, Lucknow 226001 (India)

    2009-12-30

    The ostracod Cypris subglobosa Sowerby, 1840 static bioassay test on the basis of a 48 h of 50% of immobilization (EC{sub 50}) has been used to measure the toxicity of 36 metals and metalloids and 12 reference toxicants. Among the 36 metals and metalloids, osmium (Os) was found to be the most toxic in the test while boron (B), the least toxic. The EC{sub 50} values of this study revealed positive linear relationship with the established test models of cladoceran (Daphnia magna), sludge worm (Tubifex tubifex), chironomid larvae (Chironomus tentans), protozoan (Tetrahymena pyriformis), fathead minnow (Pimephales promelas), bluegill sunfish (Lepomis macrochirus), and aquatic macrophyte duckweed (Lemna minor). Correlation coefficients (r{sup 2}) for 17 physicochemical properties of metals or metal ions and EC{sub 50}s (as pM) were examined by linear regression analysis. The electronegativity, ionization potential, melting point, solubility product of metal sulfides (pK{sub sp}), softness parameter and some other physicochemical characteristics were significantly correlated with EC{sub 50}s of metals to C. subglobosa. The reproducibility of toxicity test was determined using 12 reference toxicants. The coefficient of variability of the EC{sub 50}s ranged from 6.95% to 55.37% and variability was comparable to that noticed for D. magna and other aquatic test models. The study demonstrated the need to include crustacean ostracods in a battery of biotests to detect the presence of hazardous chemicals in soils, sewage sludges, sediments and aquatic systems.

  10. Unicellular eukaryotes as models in cell and molecular biology: critical appraisal of their past and future value.

    Science.gov (United States)

    Simon, Martin; Plattner, Helmut

    2014-01-01

    Unicellular eukaryotes have been appreciated as model systems for the analysis of crucial questions in cell and molecular biology. This includes Dictyostelium (chemotaxis, amoeboid movement, phagocytosis), Tetrahymena (telomere structure, telomerase function), Paramecium (variant surface antigens, exocytosis, phagocytosis cycle) or both ciliates (ciliary beat regulation, surface pattern formation), Chlamydomonas (flagellar biogenesis and beat), and yeast (S. cerevisiae) for innumerable aspects. Nowadays many problems may be tackled with "higher" eukaryotic/metazoan cells for which full genomic information as well as domain databases, etc., were available long before protozoa. Established molecular tools, commercial antibodies, and established pharmacology are additional advantages available for higher eukaryotic cells. Moreover, an increasing number of inherited genetic disturbances in humans have become elucidated and can serve as new models. Among lower eukaryotes, yeast will remain a standard model because of its peculiarities, including its reduced genome and availability in the haploid form. But do protists still have a future as models? This touches not only the basic understanding of biology but also practical aspects of research, such as fund raising. As we try to scrutinize, due to specific advantages some protozoa should and will remain favorable models for analyzing novel genes or specific aspects of cell structure and function. Outstanding examples are epigenetic phenomena-a field of rising interest. © 2014 Elsevier Inc. All rights reserved.

  11. Life history trade-offs and relaxed selection can decrease bacterial virulence in environmental reservoirs.

    Directory of Open Access Journals (Sweden)

    Lauri Mikonranta

    Full Text Available Pathogen virulence is usually thought to evolve in reciprocal selection with the host. While this might be true for obligate pathogens, the life histories of opportunistic pathogens typically alternate between within-host and outside-host environments during the infection-transmission cycle. As a result, opportunistic pathogens are likely to experience conflicting selection pressures across different environments, and this could affect their virulence through life-history trait correlations. We studied these correlations experimentally by exposing an opportunistic bacterial pathogen Serratia marcescens to its natural protist predator Tetrahymena thermophila for 13 weeks, after which we measured changes in bacterial traits related to both anti-predator defence and virulence. We found that anti-predator adaptation (producing predator-resistant biofilm caused a correlative attenuation in virulence. Even though the direct mechanism was not found, reduction in virulence was most clearly connected to a predator-driven loss of a red bacterial pigment, prodigiosin. Moreover, life-history trait evolution was more divergent among replicate populations in the absence of predation, leading also to lowered virulence in some of the 'predator absent' selection lines. Together these findings suggest that the virulence of non-obligatory, opportunistic bacterial pathogens can decrease in environmental reservoirs through life history trade-offs, or random accumulation of mutations that impair virulence traits under relaxed selection.

  12. Unusual features of non-dividing somatic macronuclei in the ciliate class Karyorelictea.

    Science.gov (United States)

    Yan, Ying; Rogers, Anna J; Gao, Feng; Katz, Laura A

    2017-10-01

    Genome structure and nuclear organization have been intensely studied in model ciliates such as Tetrahymena and Paramecium, yet few studies have focused on nuclear features of other ciliate clades including the class Karyorelictea. In most ciliates, both the somatic macronuclei and germline micronuclei divide during cell division and macronuclear development only occurs after conjugation. However, the macronuclei of Karyorelictea are non-dividing (i.e. division minus (Div-)) and develop anew from micronuclei during each asexual division. As macronuclei age within Karyorelictea, they undergo changes in morphology and DNA content until they are eventually degraded and replaced by newly developed macronuclei. No less than two macronuclei and one micronucleus are present in karyorelictid species, which suggests that a mature macronucleus 1) might be needed to sustain the cell while a new macronucleus is developing and 2) likely plays a role in guiding the development of the new macronucleus. Here we use a phylogenetic framework to compile information on the morphology and development of nuclei in Karyorelictea, largely relying on the work of Dr. Igor Raikov (1932-1998). We synthesize data to speculate on the functional implications of key features of Karyorelictea including the presence of at least two macronuclei in each cell and the inability for macronuclei to divide. Copyright © 2017 The Authors. Published by Elsevier GmbH.. All rights reserved.

  13. Pseudomonas aeruginosa adaptation to lungs of cystic fibrosis patients leads to lowered resistance to phage and protist enemies.

    Directory of Open Access Journals (Sweden)

    Ville-Petri Friman

    Full Text Available Pathogenic life styles can lead to highly specialized interactions with host species, potentially resulting in fitness trade-offs in other ecological contexts. Here we studied how adaptation of the environmentally transmitted bacterial pathogen, Pseudomonas aeruginosa, to cystic fibrosis (CF patients affects its survival in the presence of natural phage (14/1, ΦKZ, PNM and PT7 and protist (Tetrahymena thermophila and Acanthamoebae polyphaga enemies. We found that most of the bacteria isolated from relatively recently intermittently colonised patients (1-25 months, were innately phage-resistant and highly toxic for protists. In contrast, bacteria isolated from long time chronically infected patients (2-23 years, were less efficient in both resisting phages and killing protists. Moreover, chronic isolates showed reduced killing of wax moth larvae (Galleria mellonella probably due to weaker in vitro growth and protease expression. These results suggest that P. aeruginosa long-term adaptation to CF-lungs could trade off with its survival in aquatic environmental reservoirs in the presence of microbial enemies, while lowered virulence could reduce pathogen opportunities to infect insect vectors; factors that are both likely to result in poorer environmental transmission. From an applied perspective, phage therapy could be useful against chronic P. aeruginosa lung infections that are often characterized by multidrug resistance: chronic isolates were least resistant to phages and their poor growth will likely slow down the emergence of beneficial resistance mutations.

  14. Single-Molecule Spectroscopic Investigations of RNA Structural Dynamics

    Science.gov (United States)

    Fiore, Julie L.; Nesbitt, David J.

    2007-03-01

    To function properly, catalytic RNAs (ribozymes) fold into specific three-dimensional shapes stabilized by multiple tertiary interactions. However, only limited information is available on the contributions of individual tertiary contacts to RNA conformational dynamics. The Tetrahymena ribozymes's P4--P6 domain forms a hinged, ``candy-cane'' structure with parallel helices clamped by two motifs, the GAAA tetraloop-tetraloop receptor and adenosine (A)-rich bulge--P4 helix interactions. Previously, we characterized RNA folding due to a tetraloop-receptor interaction. In this study, we employ time-resolved single-molecule FRET methods to probe A-rich bulge induced structural dynamics. Specifically, fluorescently labeled RNA constructs excited by a pulsed 532 nm laser are detected in the confocal region of an inverted microscope, with each photon sorted by arrival time, color and polarization. We resolve the kinetic dependence of A-rich bulge-P4 helix docking/undocking on cationic environment (e.g. Na^+ and Mg^2+ concentration.) At saturating [Mg^2+], the docked structure appears only weakly stabilized, while only 50% of the molecules exhibit efficient folding.

  15. Bioinformatic and proteomic analysis of bulk histones reveals PTM crosstalk and chromatin features.

    Science.gov (United States)

    Zhang, Chunchao; Gao, Shan; Molascon, Anthony J; Wang, Zhe; Gorovsky, Martin A; Liu, Yifan; Andrews, Philip C

    2014-07-03

    Systems analysis of chromatin has been constrained by complex patterns and dynamics of histone post-translational modifications (PTMs), which represent major challenges for both mass spectrometry (MS) and immuno-based approaches (e.g., chromatin immuno-precipitation, ChIP). Here we present a proof-of-concept study demonstrating that crosstalk among PTMs and their functional significance can be revealed via systematic bioinformatic and proteomic analysis of steady-state histone PTM levels from cells under various perturbations. Using high resolution tandem MS, we quantified 53 modification states from all core histones and their conserved variants in the unicellular eukaryotic model organism Tetrahymena. By correlating histone PTM patterns across 15 different conditions, including various physiological states and mutations of key histone modifying enzymes, we identified 5 specific chromatin states with characteristic covarying histone PTMs and associated them with distinctive functions in replication, transcription, and DNA repair. In addition to providing a detailed picture on histone PTM crosstalk at global levels, this work has established a novel bioinformatic and proteomic approach, which can be adapted to other organisms and readily scaled up to allow increased resolution of chromatin states.

  16. Characterization of ciliate diversity in bromeliad tank waters from the Brazilian Atlantic Forest.

    Science.gov (United States)

    Simão, Taiz L L; Borges, Adriana Giongo; Gano, Kelsey A; Davis-Richardson, Austin G; Brown, Christopher T; Fagen, Jennie R; Triplett, Eric W; Dias, Raquel; Mondin, Claudio A; da Silva, Renata M; Eizirik, Eduardo; Utz, Laura R P

    2017-10-01

    Bromeliads are a diverse group of plants that includes many species whose individuals are capable of retaining water, forming habitats called phytotelmata. These habitats harbor a diversity of organisms including prokaryotes, unicellular eukaryotes, metazoans, and fungi. Among single-celled eukaryotic organisms, ciliates are generally the most abundant. In the present study, we used Illumina DNA sequencing to survey the eukaryotic communities, especially ciliates, inhabiting the tanks of the bromeliads Aechmea gamosepala and Vriesea platynema in the Atlantic Forest of southern Brazil. Filtered sequences were clustered into distinct OTUs using a 99% identity threshold, and then assigned to phylum and genus using a BLAST-based approach (implemented in QIIME) and the SILVA reference database. Both bromeliad species harbored very diverse eukaryotic communities, with Arthropoda and Ciliophora showing the highest abundance (as estimated by the number of sequence reads). The ciliate genus Tetrahymena was the most abundant among single-celled organisms, followed by apicomplexan gregarines and the ciliate genus Glaucoma. Another interesting finding was the presence and high abundance of Trypanosoma in these bromeliad tanks, demonstrating their occurrence in this type of environment. The results presented here demonstrate a hidden diversity of eukaryotes in bromeliad tank waters, opening up new avenues for their in-depth characterization. Copyright © 2017 The Authors. Published by Elsevier GmbH.. All rights reserved.

  17. Roles for RpoS in survival of Escherichia coli during protozoan predation and in reduced moisture conditions highlight its importance in soil environments.

    Science.gov (United States)

    Somorin, Yinka; Bouchard, Guillaume; Gallagher, Joseph; Abram, Florence; Brennan, Fiona; O'Byrne, Conor

    2017-10-16

    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. Strain-specific differences were observed in the predation of E. coli strains, with soil-persistent strain COB583 being the most resistant to predation by both protozoans. RpoS and curli, proteinaceous fibres used for attachment to biotic and abiotic surfaces, increased the ability of E. coli to resist predation by A. polyphaga and T. pyriformis. Furthermore, soil moisture content impacted the survival of E. coli BW25113 but wild-type COB583 had similar survival irrespective of soil moisture content. Overall, this study confirmed that RpoS contributes to the resistance of E. coli to protozoan predation and that RpoS is crucial for the increased fitness of soil-persistent E. coli against predation and reduced moisture in soil. © FEMS 2017. All rights reserved. For permissions, please e-mail: journals.permissions@oup.com.

  18. Mapping the kinetic barriers of a Large RNA molecule's folding landscape.

    Directory of Open Access Journals (Sweden)

    Jörg C Schlatterer

    Full Text Available The folding of linear polymers into discrete three-dimensional structures is often required for biological function. The formation of long-lived intermediates is a hallmark of the folding of large RNA molecules due to the ruggedness of their energy landscapes. The precise thermodynamic nature of the barriers (whether enthalpic or entropic that leads to intermediate formation is still poorly characterized in large structured RNA molecules. A classic approach to analyzing kinetic barriers are temperature dependent studies analyzed with Eyring's transition state theory. We applied Eyring's theory to time-resolved hydroxyl radical (•OH footprinting kinetics progress curves collected at eight temperature from 21.5 °C to 51 °C to characterize the thermodynamic nature of folding intermediate formation for the Mg(2+-mediated folding of the Tetrahymena thermophila group I ribozyme. A common kinetic model configuration describes this RNA folding reaction over the entire temperature range studied consisting of primary (fast transitions to misfolded intermediates followed by much slower secondary transitions, consistent with previous studies. Eyring analysis reveals that the primary transitions are moderate in magnitude and primarily enthalpic in nature. In contrast, the secondary transitions are daunting in magnitude and entropic in nature. The entropic character of the secondary transitions is consistent with structural rearrangement of the intermediate species to the final folded form. This segregation of kinetic control reveals distinctly different molecular mechanisms during the two stages of RNA folding and documents the importance of entropic barriers to defining rugged RNA folding landscapes.

  19. Identification and characterization of a putative agglutination/immobilization antigen on the surface of Cryptocaryon irritans.

    Science.gov (United States)

    Hatanaka, A; Umeda, N; Yamashita, S; Hirazawa, N

    2007-08-01

    The ciliated protozoan Cryptocaryon irritans, a parasite of seawater fishes, was found to express an antigen that elicits antibodies in rabbits and tiger puffer (Takifugu ruburipes). Serum from rabbits and fish immunized with theronts had agglutination/immobilization activity against theronts in vitro; fish serum antibody levels (measured by enzyme-linked immunosorbent assays: ELISA) correlated with this activity. Anti-theront antibody levels in fish were significantly higher in the immunized group as compared with control fish at 2 weeks after booster immunization (injection of bovine serum albumin; Student's t-test, P<0.01). Biochemical analyses indicated that a Triton X-114-soluble 32 kDa theront integral membrane protein may be the agglutination/immobilization antigen. Indirect immunofluorescence staining of theronts suggested that this 32 kDa antigen was expressed on the surface of cilia. The full-length 32 kDa antigen cDNA contained 1147 basepairs, encoding a 328-amino acid protein including hydrophobic N- and C-termini. As with Tetrahymena and Paramecium spp., TAA and TAG appear to be used as glutamine codons in the 32 kDa antigen gene.

  20. Kinesin-13 regulates the quantity and quality of tubulin inside cilia

    Science.gov (United States)

    Vasudevan, Krishna Kumar; Jiang, Yu-Yang; Lechtreck, Karl F.; Kushida, Yasuharu; Alford, Lea M.; Sale, Winfield S.; Hennessey, Todd; Gaertig, Jacek

    2015-01-01

    Kinesin-13, an end depolymerizer of cytoplasmic and spindle microtubules, also affects the length of cilia. However, in different models, depletion of kinesin-13 either lengthens or shortens cilia, and therefore the exact function of kinesin-13 in cilia remains unclear. We generated null mutations of all kinesin-13 paralogues in the ciliate Tetrahymena. One of the paralogues, Kin13Ap, localizes to the nuclei and is essential for nuclear divisions. The remaining two paralogues, Kin13Bp and Kin13Cp, localize to the cell body and inside assembling cilia. Loss of both Kin13Bp and Kin13Cp resulted in slow cell multiplication and motility, overgrowth of cell body microtubules, shortening of cilia, and synthetic lethality with either paclitaxel or a deletion of MEC-17/ATAT1, the α-tubulin acetyltransferase. The mutant cilia assembled slowly and contained abnormal tubulin, characterized by altered posttranslational modifications and hypersensitivity to paclitaxel. The mutant cilia beat slowly and axonemes showed reduced velocity of microtubule sliding. Thus kinesin-13 positively regulates the axoneme length, influences the properties of ciliary tubulin, and likely indirectly, through its effects on the axonemal microtubules, affects the ciliary dynein-dependent motility. PMID:25501369

  1. Mechanisms of action of aminoglycoside antibiotics in eucaryotic protein synthesis.

    Science.gov (United States)

    Eustice, D C; Wilhelm, J M

    1984-01-01

    Tetrahymena thermophila is a eucaryotic organism that is highly susceptible to growth inhibition by aminoglycoside antibiotics. Concentrations of paromomycin, gentamicin G418, and hygromycin B at 22, 10, and 17 microM, respectively, inhibited growth by 50%. A combination of in vitro and in vivo methods was used to determine the mechanisms of action of these aminoglycoside antibiotics on protein synthesis in T. thermophila. Analysis of polysome profiles from paromomycin- and gentamicin G418-treated cells showed clear, progressive depletions of polysomes concomitant with an inhibition of in vivo [14C] lysine incorporation. In vitro, paromomycin and gentamicin G418, which are disubstituted 2-deoxystreptamine-containing molecules, were not very effective inhibitors of either the translocation of peptidyl-tRNA or the elongation of nascent polypeptide chains on polysomes. In contrast, we found that the translocation of phe-tRNA on polyuridylate programmed ribosomes was susceptible to inhibition by paromomycin. We conclude that the primary inhibitory action of paromomycin and gentamicin G418 was at (i) an early stage of elongation after initiation, (ii) the initiation stage of translation, or (iii) a stage of translation before initiation. Hygromycin B, which is a monosubstituted 2-deoxystreptamine-containing aminoglycoside, potently inhibited the elongation of nascent chains during the translation of polysomes. In addition, the in vitro translation of polysomes from two hygromycin B-resistant mutants was resistant to the inhibition of elongation caused by hygromycin B. PMID:6433789

  2. A distinct pathway for tetrahymanol synthesis in bacteria

    Science.gov (United States)

    Banta, Amy B.; Wei, Jeremy H.; Welander, Paula V.

    2015-11-01

    Tetrahymanol is a polycyclic triterpenoid lipid first discovered in the ciliate Tetrahymena pyriformis whose potential diagenetic product, gammacerane, is often used as a biomarker for water column stratification in ancient ecosystems. Bacteria are also a potential source of tetrahymanol, but neither the distribution of this lipid in extant bacteria nor the significance of bacterial tetrahymanol synthesis for interpreting gammacerane biosignatures is known. Here we couple comparative genomics with genetic and lipid analyses to link a protein of unknown function to tetrahymanol synthesis in bacteria. This tetrahymanol synthase (Ths) is found in a variety of bacterial genomes, including aerobic methanotrophs, nitrite-oxidizers, and sulfate-reducers, and in a subset of aquatic and terrestrial metagenomes. Thus, the potential to produce tetrahymanol is more widespread in the bacterial domain than previously thought. However, Ths is not encoded in any eukaryotic genomes, nor is it homologous to eukaryotic squalene-tetrahymanol cyclase, which catalyzes the cyclization of squalene directly to tetrahymanol. Rather, heterologous expression studies suggest that bacteria couple the cyclization of squalene to a hopene molecule by squalene-hopene cyclase with a subsequent Ths-dependent ring expansion to form tetrahymanol. Thus, bacteria and eukaryotes have evolved distinct biochemical mechanisms for producing tetrahymanol.

  3. Ecological effects of various toxic agents on the aquatic microcosm in comparison with acute ionizing radiation

    Energy Technology Data Exchange (ETDEWEB)

    Fuma, S. E-mail: fuma@nirs.go.jp; Ishii, N.; Takeda, H.; Miyamoto, K.; Yanagisawa, K.; Ichimasa, Y.; Saito, M.; Kawabata, Z.; Polikarpov, G.G

    2003-07-01

    The purpose of this study was an evaluation of the effect levels of various toxic agents compared with acute doses of ionizing radiation for the experimental model ecosystem, i.e., microcosm mimicking aquatic microbial communities. For this purpose, the authors used the microcosm consisting of populations of the flagellate alga Euglena gracilis as a producer, the ciliate protozoan Tetrahymena thermophila as a consumer and the bacterium Escherichia coli as a decomposer. Effects of aluminum and copper on the microcosm were investigated in this study, while effects of {gamma}-rays, ultraviolet radiation, acidification, manganese, nickel and gadolinium were reported in previous studies. The microcosm could detect not only the direct effects of these agents but also the community-level effects due to the interspecies interactions or the interactions between organisms and toxic agents. The authors evaluated doses or concentrations of each toxic agent which had the following effects on the microcosm: (1) no effects; (2) recognizable effects, i.e., decrease or increase in the cell densities of at least one species; (3) severe effects, i.e., extinction of one or two species; and (4) destructive effects, i.e., extinction of all species. The resulting effects data will contribute to an ecological risk assessment of the toxic agents compared with acute doses of ionizing radiation.

  4. The effects of resource enrichment, dispersal, and predation on local and metacommunity structure.

    Science.gov (United States)

    Cadotte, Marc W; Fortner, Allison M; Fukami, Tadashi

    2006-08-01

    Community structure is the observable outcome of numerous processes. We conducted a laboratory experiment using a microbial model system to disentangle effects of nutrient enrichment, dispersal, and predation on prey species richness and predator abundance at local and metacommunity scales. Prey species included: Chilomonas sp., Colpidium striatum, Colpoda cucullus, Paramecium tetraurelia, P. caudatum, Philodina sp., Spirostomum sp., Tetrahymena thermophila, and Uronema sp., and Stentor coeruleus was the predator used. We hypothesized that: (1) increased basal resources should maintain greater species richness and higher predator abundance; (2) dispersal should maintain greater species richness; and (3) predation should reduce species richness, especially in the high resource treatments relative to no-predator treatments. Our results support all three hypotheses. Further, we show that dispersal affects richness at the local community scale but not at the metacommunity scale. However, predation seems to have major effects at both the local and metacommunity scale. Overall, our results show that effects of resource enrichment, dispersal, and predation were mostly additive rather than interactive, indicating that it may be sometimes easier to understand their effects than generally thought due to complex interactive effects.

  5. Did Gause Have a Yeast Infection?

    Science.gov (United States)

    Pritchard, Jonathon O; Porter, Alice H M; Montagnes, David J S

    2016-09-01

    We planned to develop predator-prey models using Paramecium and yeast, but they have not been empirically examined since work by Gause in the 1930s. Therefore, we evaluated if Paramecium aurelia ingests and grows on eight yeasts. Recognising that it ingested yeasts but could not grow, we assessed if it might grow on other yeasts, by empirically parameterising a predator-prey model that relies on ingestion, not growth. Simulations were compared to P. aurelia-yeast time-series data, from Gause. We hypothesised that if the model simulated predator-prey dynamics that mimicked the original data, then possibly P. aurelia could grow on yeast; simulations did not mimic the original data. Reviewing works by Gause exposed two issues: experiments were undoubtedly contaminated with bacteria, allowing growth on bacteria, not yeast; and the population cycle data cannot be considered a self-sustaining time series, as they were manipulated by adding yeast and ciliates. We conclude that past and future work should not rely on this system, for either empirical or theoretical evaluations. Finally, although we show that P. aurelia, P. caudatum, Euplotes patella, and Blepharisma sp. cannot grow on yeast, Tetrahymena pyriformis and Colpidium striatum can; these may provide models to explore predator-prey dynamics. © 2016 The Author(s) Journal of Eukaryotic Microbiology © 2016 International Society of Protistologists.

  6. Ultradian clocks in eukaryotic microbes: from behavioural observation to functional genomics.

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    Kippert, F; Hunt, P

    2000-01-01

    Period homeostasis is the defining characteristic of a biological clock. Strict period homeostasis is found for the ultradian clocks of eukaryotic microbes. In addition to being temperature-compensated, the period of these rhythms is unaffected by differences in nutrient composition or changes in other environmental variables. The best-studied examples of ultradian clocks are those of the ciliates Paramecium tetraurelia and Tetrahymena sp. and of the fission yeast, Schizosaccharomyces pombe. In these single cell eukaryotes, up to seven different parameters display ultradian rhythmicity with the same, species- and strain-specific period. In fission yeast, the molecular genetic analysis of ultradian clock mechanisms has begun with the systematic analysis of mutants in identified candidate genes. More than 40 "clock mutants" have already been identified, most of them affected in components of major regulatory and signalling pathways. These results indicate a high degree of complexity for a eukaryotic clock mechanism. BioEssays 22:16-22, 2000. Copyright 2000 John Wiley & Sons, Inc.

  7. Spliceozymes: ribozymes that remove introns from pre-mRNAs in trans.

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    Zhaleh N Amini

    Full Text Available Group I introns are pre-mRNA introns that do not require the spliceosome for their removal. Instead, they fold into complex three-dimensional structures and catalyze two transesterification reactions, thereby excising themselves and joining the flanking exons. These catalytic RNAs (ribozymes have been modified previously to work in trans, whereby the ribozymes can recognize a splice site on a substrate RNA and replace the 5'- or 3'-portion of the substrate. Here we describe a new variant of the group I intron ribozyme from Tetrahymena that recognizes two splice sites on a substrate RNA, removes the intron sequences between the splice sites, and joins the flanking exons, analogous to the action of the spliceosome. This 'group I spliceozyme' functions in vitro and in vivo, and it is able to mediate a growth phenotype in E. coli cells. The intron sequences of the target pre-mRNAs are constrained near the splice sites but can carry a wide range of sequences in their interior. Because the splice site recognition sequences can be adjusted to different splice sites, the spliceozyme may have the potential for wide applications as tool in research and therapy.

  8. Torque Generation by Axonemal Outer-Arm Dynein

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    Yamaguchi, Shin; Saito, Kei; Sutoh, Miki; Nishizaka, Takayuki; Toyoshima, Yoko Y; Yajima, Junichiro

    2015-01-01

    Outer-arm dynein is the main engine providing the motive force in cilia. Using three-dimensional tracking microscopy, we found that contrary to previous reports Tetrahymena ciliary three-headed outer-arm dynein (αβγ) as well as proteolytically generated two-headed (βγ) and one-headed (α) subparticles showed clockwise rotation of each sliding microtubule around its longitudinal axis in microtubule corkscrewing assays. By measuring the rotational pitch as a function of ATP concentration, we also found that the microtubule corkscrewing pitch is independent of ATP concentration, except at low ATP concentrations where the pitch generated by both three-headed αβγ and one-headed α exhibited significantly longer pitch. In contrast, the pitch driven by two-headed βγ did not display this sensitivity. In the assays on lawns containing mixtures of α and βγ at various ratios, the corkscrewing pitch increased dramatically in a nonlinear fashion as the ratio of α in the mixture increased. Even small proportions of α-subparticle could significantly increase the corkscrewing pitch of the mixture. Our data show that torque generation does not require the three-headed outer-arm dynein (αβγ) but is an intrinsic property of the subparticles of axonemal dyneins and also suggest that each subparticle may have distinct mechanical properties. PMID:25692592

  9. A comparison of the crystal structures of eukaryotic and bacterial SSU ribosomal RNAs reveals common structural features in the hypervariable regions.

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    Jung C Lee

    Full Text Available While the majority of the ribosomal RNA structure is conserved in the three major domains of life--archaea, bacteria, and eukaryotes, specific regions of the rRNA structure are unique to at least one of these three primary forms of life. In particular, the comparative secondary structure for the eukaryotic SSU rRNA contains several regions that are different from the analogous regions in the bacteria. Our detailed analysis of two recently determined eukaryotic 40S ribosomal crystal structures, Tetrahymena thermophila and Saccharomyces cerevisiae, and the comparison of these results with the bacterial Thermus thermophilus 30S ribosomal crystal structure: (1 revealed that the vast majority of the comparative structure model for the eukaryotic SSU rRNA is substantiated, including the secondary structure that is similar to both bacteria and archaea as well as specific for the eukaryotes, (2 resolved the secondary structure for regions of the eukaryotic SSU rRNA that were not determined with comparative methods, (3 identified eukaryotic helices that are equivalent to the bacterial helices in several of the hypervariable regions, (4 revealed that, while the coaxially stacked compound helix in the 540 region in the central domain maintains the constant length of 10 base pairs, its two constituent helices contain 5+5 bp rather than the 6+4 bp predicted with comparative analysis of archaeal and eukaryotic SSU rRNAs.

  10. The Trojan Horse of the microbiological arms race: phage-encoded toxins as a defence against eukaryotic predators.

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    Arnold, Jason W; Koudelka, Gerald B

    2014-02-01

    Phage-encoded Shiga toxin (Stx) acts as a bacterial defence against the eukaryotic predator Tetrahymena. To function as an effective bacterial anti-predator defence, Stx must kill a broad spectrum of predators. Consistent with that assertion, we show here that bacterially encoded Stx efficiently kills the bacteriovore Acanthamoeba castellanii in co-culture. We also show that, in addition to Stx, the phage-encoded exotoxin, diphtheria toxin (Dtx) expressed by Corynebacterium diphtheriae also can function as part of an anti-predator strategy; it kills Acanthamoeba in co-culture. Interestingly, only exotoxins produced by bacteria internalized by the Acanthamoeba predator are cytolethal; the presence of purified Dtx or Stx in culture medium has no effect on predator viability. This finding is consistent with our results indicating that intoxication of Acanthamoeba by these exotoxins does not require a receptor. Thus bacteria, in the disguise of a food source, function as a 'Trojan Horse', carrying genes encoding an exotoxin into target organisms. This 'Trojan Horse' mechanism of exotoxin delivery into predator cells allows intoxication of predators that lack a cell surface receptor for the particular toxin, allowing bacteria-bearing exotoxins to kill a broader spectrum of predators, increasing the fitness of the otherwise 'defenceless' prey bacteria. © 2013 Society for Applied Microbiology and John Wiley & Sons Ltd.

  11. The mitoribosomes of a chloramphenicol-resistant cytoplasmic mutant of Tetrahymnea pyriformis differ from those of the wild strain.

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    Curgy, J J; Perasso, R; Boissonneau, E; Iftode, F; Stelly, N; Andre, J

    1981-11-01

    The spontaneous CAP-resistant mutant, STR1, has been isolated from the sensitive St-strain of Tetrahymena pyriformis (Curgy et al., Biologie Cellulaire 37, 51-60, 1980; Perasso et al., Biologie Cellulaire 37, 45-50, 1980). The goal of the present work is to disclose if the resistance character is due to a modification in the mitoribosomes and if the CAP-treatment induces changes in their abundance and in their physico-chemical properties.The results show that the resistance character of the mutant is due to a reduced affinity of its mitoribosomes for CAP. This difference can be explained by modifications of at least one protein which is probably coded for by the mitochondrial genome.The mitoribosomes from CAP-treated sensitive cells tend to dissociate into their subunits and the electrophoretic pattern of their proteins suggests that at least two mitoribosomal proteins are necessary to bound the two subunits together. These proteins are probably translated in mitochondria.Finally, the CAP-treatment induces a decrease of the abundance of mitoribosomes in the sensitive cells whereas it induced an increase in the resistant cells. The latter change can be regarded as a regulatory mechanism owing to which a loss of efficiency of the mitoribosomes is compensated by their enlarged abundance.

  12. Ecotoxicity evaluation of a WWTP effluent treated by solar photo-Fenton at neutral pH in a raceway pond reactor.

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    Freitas, A M; Rivas, G; Campos-Mañas, M C; Casas López, J L; Agüera, A; Sánchez Pérez, J A

    2017-01-01

    Some pollutants can be resistant to wastewater treatment, hence becoming a risk to aquatic and terrestrial biota even at the very low concentrations (ng L -1 -μg L -1 ) they are commonly found at. Tertiary treatments are used for micropollutant removal but little is known about the ecotoxicity of the treated effluent. In this study, a municipal secondary effluent was treated by a solar photo-Fenton reactor at initial neutral pH in a raceway pond reactor, and ecotoxicity was evaluated before and after micropollutant removal. Thirty-nine micropollutants were identified in the secondary effluent, mainly pharmaceuticals, with a total concentration of ≈80 μg L -1 . After treatment, 99 % microcontaminant degradation was reached. As for ecotoxicity reduction, the assayed organisms showed the following sensitivity levels: Tetrahymena thermophila > Daphnia magna > Lactuca sativa > Spirodela polyrhiza ≈ Vibrio fischeri. The initial effluent showed an inhibitory effect of 40 % for T. thermophila and 20 % for D. magna. After 20 min of photo-Fenton treatment, no toxic effect was observed for T. thermophila and toxicity dropped to 5 % for D. magna. Graphical abstract Ecotoxicity removal by solar photo-Fenton at neutral pH. ᅟ.

  13. The novel measuring method for screening and assessing chromium content in clothes and shoes materials

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    Salerno-Kochan, R.

    2017-10-01

    The aim of this paper is to propose the bioindicative measuring method for screening and assessing the safety of textile and leather materials in relation to chemical threats. This method is based on toxicological assay in which Tetrahymena pyriformis, unicellular organism belonging to protozoans, is used as a test organism. For the realization of the research goal the sensitivity threshold of test organisms to chromium(VI) solutions was identified. The changes in cell development of test organisms in chromium solutions were registered by colorimetric measurements in the presence of alamarBlue® cell viability reagent. Empirical data enabled to fit logistic curves on the base of which the level of chromium toxicity was estimated. In the second step, harmfulness of aqueous extracts obtained from textile and leather samples containing chromium in relation to test organisms was evaluated. The performed research confirmed the high efficiency of the proposed method in screening and assessing chromium content in clothes and shoes materials and showed possibilities of using it in safety assessment of products with regard to chemical risks.

  14. Preliminary study on applicability of microsatellite DNA primers from parasite protozoa Trypanosoma cruzi in free-living protozoa

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    Zhang, Wenjing; Yu, Yuhe; Shen, Yunfen; Miao, Wei; Feng, Weisong

    2004-04-01

    In this paper, we took the lead in studying on specificity of the microsatellite DNA loci and applicability of microsatellite DNA primers in protozoa. In order to study characters of microsatellites in free-living protozoa, eight microsatellite loci primers developed from Trypanosoma cruzi (MCLE01, SCLE10, MCLE08, SCLE11, MCLF10, MCLG10, MCL03, MCL05) were employed to amplify microsatellite in four free-living protozoa, including Bodo designis, Euglena gracilis FACHB848, Paramecium bruzise and Tetrahymena thermophila BF1. In the amplification systems of P. bruzise, four loci (SCLE10, SCLE11, MCLF10, MCL03) were amplified successfully, and four amplification fragments were in proper size. In genome of E. gracilis FACHB848, five of eight primers brought five clear amplification bands. In B. designis, three (No.4, 5 and 7) of eight loci produced clear and sharp products without stutter bands, whereas no bands appeared in T. thermophila BF1. Further, eight 300 500 bp amplification fragments were cloned and sequenced. Nevertheless, all sequenced products did not contain corresponding microsatellite sequence, although Bodo is in the same order and has the nearest phylogenetic relation with Trypanosoma among these four species. Thus, the microsatellite DNA primers can not be applied among order or more far taxa, and the specificity of microsatellite DNA is very high in protozoa. The results of this study will contribute to our understanding of microsatellite DNA in protozoa.

  15. Horizontal gene transfer from Bacteria to rumen Ciliates indicates adaptation to their anaerobic, carbohydrates-rich environment

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    Takenaka Akio

    2006-02-01

    Full Text Available Abstract Background The horizontal transfer of expressed genes from Bacteria into Ciliates which live in close contact with each other in the rumen (the foregut of ruminants was studied using ciliate Expressed Sequence Tags (ESTs. More than 4000 ESTs were sequenced from representatives of the two major groups of rumen Cilates: the order Entodiniomorphida (Entodinium simplex, Entodinium caudatum, Eudiplodinium maggii, Metadinium medium, Diploplastron affine, Polyplastron multivesiculatum and Epidinium ecaudatum and the order Vestibuliferida, previously called Holotricha (Isotricha prostoma, Isotricha intestinalis and Dasytricha ruminantium. Results A comparison of the sequences with the completely sequenced genomes of Eukaryotes and Prokaryotes, followed by large-scale construction and analysis of phylogenies, identified 148 ciliate genes that specifically cluster with genes from the Bacteria and Archaea. The phylogenetic clustering with bacterial genes, coupled with the absence of close relatives of these genes in the Ciliate Tetrahymena thermophila, indicates that they have been acquired via Horizontal Gene Transfer (HGT after the colonization of the gut by the rumen Ciliates. Conclusion Among the HGT candidates, we found an over-representation (>75% of genes involved in metabolism, specifically in the catabolism of complex carbohydrates, a rich food source in the rumen. We propose that the acquisition of these genes has greatly facilitated the Ciliates' colonization of the rumen providing evidence for the role of HGT in the adaptation to new niches.

  16. Predation response of Vibrio fischeri biofilms to bacterivorus protists.

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    Chavez-Dozal, Alba; Gorman, Clayton; Erken, Martina; Steinberg, Peter D; McDougald, Diane; Nishiguchi, Michele K

    2013-01-01

    Vibrio fischeri proliferates in a sessile, stable community known as a biofilm, which is one alternative survival strategy of its life cycle. Although this survival strategy provides adequate protection from abiotic factors, marine biofilms are still susceptible to grazing by bacteria-consuming protozoa. Subsequently, grazing pressure can be controlled by certain defense mechanisms that confer higher biofilm antipredator fitness. In the present work, we hypothesized that V. fischeri exhibits an antipredator fitness behavior while forming biofilms. Different predators representing commonly found species in aquatic populations were examined, including the flagellates Rhynchomonas nasuta and Neobodo designis (early biofilm feeders) and the ciliate Tetrahymena pyriformis (late biofilm grazer). V. fischeri biofilms included isolates from both seawater and squid hosts (Euprymna and Sepiola species). Our results demonstrate inhibition of predation by biofilms, specifically, isolates from seawater. Additionally, antiprotozoan behavior was observed to be higher in late biofilms, particularly toward the ciliate T. pyriformis; however, inhibitory effects were found to be widespread among all isolates tested. These results provide an alternative explanation for the adaptive advantage and persistence of V. fischeri biofilms and provide an important contribution to the understanding of defensive mechanisms that exist in the out-of-host environment.

  17. Introducing Spectral Structure Activity Relationship (S-SAR Analysis. Application to Ecotoxicology

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    Ana-Maria Lacrămă

    2007-05-01

    Full Text Available A novel quantitative structure-activity (property relationship model, namelySpectral-SAR, is presented in an exclusive algebraic way replacing the old-fashionedmulti-regression one. The actual S-SAR method interprets structural descriptors as vectorsin a generic data space that is further mapped into a full orthogonal space by means of theGram-Schmidt algorithm. Then, by coordinated transformation between the data andorthogonal spaces, the S-SAR equation is given under simple determinant form for anychemical-biological interactions under study. While proving to give the same analyticalequation and correlation results with standard multivariate statistics, the actual S-SARframe allows the introduction of the spectral norm as a valid substitute for the correlationfactor, while also having the advantage to design the various related SAR models throughthe introduced “minimal spectral path” rule. An application is given performing a completeS-SAR analysis upon the Tetrahymena pyriformis ciliate species employing its reportedeco-toxicity activities among relevant classes of xenobiotics. By representing the spectralnorm of the endpoint models against the concerned structural coordinates, the obtainedS-SAR endpoints hierarchy scheme opens the perspective to further design the eco-toxicological test batteries with organisms from different species.

  18. Tubulin glutamylation regulates ciliary motility by altering inner dynein arm activity.

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    Suryavanshi, Swati; Eddé, Bernard; Fox, Laura A; Guerrero, Stella; Hard, Robert; Hennessey, Todd; Kabi, Amrita; Malison, David; Pennock, David; Sale, Winfield S; Wloga, Dorota; Gaertig, Jacek

    2010-03-09

    How microtubule-associated motor proteins are regulated is not well understood. A potential mechanism for spatial regulation of motor proteins is provided by posttranslational modifications of tubulin subunits that form patterns on microtubules. Glutamylation is a conserved tubulin modification [1] that is enriched in axonemes. The enzymes responsible for this posttranslational modification, glutamic acid ligases (E-ligases), belong to a family of proteins with a tubulin tyrosine ligase (TTL) homology domain (TTL-like or TTLL proteins) [2]. We show that in cilia of Tetrahymena, TTLL6 E-ligases generate glutamylation mainly on the B-tubule of outer doublet microtubules, the site of force production by ciliary dynein. Deletion of two TTLL6 paralogs caused severe deficiency in ciliary motility associated with abnormal waveform and reduced beat frequency. In isolated axonemes with a normal dynein arm composition, TTLL6 deficiency did not affect the rate of ATP-induced doublet microtubule sliding. Unexpectedly, the same TTLL6 deficiency increased the velocity of microtubule sliding in axonemes that also lack outer dynein arms, in which forces are generated by inner dynein arms. We conclude that tubulin glutamylation on the B-tubule inhibits the net force imposed on sliding doublet microtubules by inner dynein arms.

  19. Evolution of density-dependent movement during experimental range expansions.

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    Fronhofer, E A; Gut, S; Altermatt, F

    2017-12-01

    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. Although rare, we found evolutionary changes during range expansions even in the absence of initial standing genetic variation. Range expansions led to the evolution of negatively density-dependent movement at range margins. In addition, we report the evolution of increased intrastrain competitive ability and concurrently decreased population growth rates in range cores. Our findings highlight the importance of understanding movement and dispersal as evolving reaction norms and plastic life-history traits of central relevance for range expansions, biological invasions and the dynamics of spatially structured systems in general. © 2017 European Society For Evolutionary Biology. Journal of Evolutionary Biology © 2017 European Society For Evolutionary Biology.

  20. Single-molecule FRET-Rosetta reveals RNA structural rearrangements during human telomerase catalysis.

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    Parks, Joseph W; Kappel, Kalli; Das, Rhiju; Stone, Michael D

    2017-02-01

    Maintenance of telomeres by telomerase permits continuous proliferation of rapidly dividing cells, including the majority of human cancers. Despite its direct biomedical significance, the architecture of the human telomerase complex remains unknown. Generating homogeneous telomerase samples has presented a significant barrier to developing improved structural models. Here we pair single-molecule Förster resonance energy transfer (smFRET) measurements with Rosetta modeling to map the conformations of the essential telomerase RNA core domain within the active ribonucleoprotein. FRET-guided modeling places the essential pseudoknot fold distal to the active site on a protein surface comprising the C-terminal element, a domain that shares structural homology with canonical polymerase thumb domains. An independently solved medium-resolution structure of Tetrahymena telomerase provides a blind test of our modeling methodology and sheds light on the structural homology of this domain across diverse organisms. Our smFRET-Rosetta models reveal nanometer-scale rearrangements within the RNA core domain during catalysis. Taken together, our FRET data and pseudoatomic molecular models permit us to propose a possible mechanism for how RNA core domain rearrangement is coupled to template hybrid elongation. © 2017 Parks et al.; Published by Cold Spring Harbor Laboratory Press for the RNA Society.

  1. Cooperative social clusters are not destroyed by dispersal in a ciliate.

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    Schtickzelle, Nicolas; Fjerdingstad, Else J; Chaine, Alexis; Clobert, Jean

    2009-10-14

    The evolution of social cooperation is favored by aggregative behavior to facilitate stable social structure and proximity among kin. High dispersal rates reduce group stability and kin cohesion, so it is generally assumed that there is a fundamental trade-off between cooperation and dispersal. However, empirical tests of this relationship are rare. We tested this assumption experimentally using ten genetically isolated strains of a ciliate, Tetrahymena thermophila. The propensity for social aggregation was greater in strains with reduced cell quality and lower growth performance. While we found a trade-off between costly aggregation and local dispersal in phenotypic analyses, aggregative strains showed a dispersal polymorphism by producing either highly sedentary or long-distance dispersive cells, in contrast to less aggregative strains whose cells were monomorphic local dispersers. High dispersal among aggregative strains may not destroy group stability in T. thermophila because the dispersal polymorphism allows social strains to more readily escape kin groups than less aggregative strains, yet still benefit from stable group membership among sedentary morphs. Such dispersal polymorphisms should be common in other social organisms, serving to alter the nature of the negative impact of dispersal on social evolution.

  2. Cooperative social clusters are not destroyed by dispersal in a ciliate

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    Chaine Alexis

    2009-10-01

    Full Text Available Abstract Background The evolution of social cooperation is favored by aggregative behavior to facilitate stable social structure and proximity among kin. High dispersal rates reduce group stability and kin cohesion, so it is generally assumed that there is a fundamental trade-off between cooperation and dispersal. However, empirical tests of this relationship are rare. We tested this assumption experimentally using ten genetically isolated strains of a ciliate, Tetrahymena thermophila. Results The propensity for social aggregation was greater in strains with reduced cell quality and lower growth performance. While we found a trade-off between costly aggregation and local dispersal in phenotypic analyses, aggregative strains showed a dispersal polymorphism by producing either highly sedentary or long-distance dispersive cells, in contrast to less aggregative strains whose cells were monomorphic local dispersers. Conclusion High dispersal among aggregative strains may not destroy group stability in T. thermophila because the dispersal polymorphism allows social strains to more readily escape kin groups than less aggregative strains, yet still benefit from stable group membership among sedentary morphs. Such dispersal polymorphisms should be common in other social organisms, serving to alter the nature of the negative impact of dispersal on social evolution.

  3. A simple microscopy assay to teach the processes of phagocytosis and exocytosis.

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    Gray, Ross; Gray, Andrew; Fite, Jessica L; Jordan, Renée; Stark, Sarah; Naylor, Kari

    2012-01-01

    Phagocytosis and exocytosis are two cellular processes involving membrane dynamics. While it is easy to understand the purpose of these processes, it can be extremely difficult for students to comprehend the actual mechanisms. As membrane dynamics play a significant role in many cellular processes ranging from cell signaling to cell division to organelle renewal and maintenance, we felt that we needed to do a better job of teaching these types of processes. Thus, we developed a classroom-based protocol to simultaneously study phagocytosis and exocytosis in Tetrahymena pyriformis. In this paper, we present our results demonstrating that our undergraduate classroom experiment delivers results comparable with those acquired in a professional research laboratory. In addition, students performing the experiment do learn the mechanisms of phagocytosis and exocytosis. Finally, we demonstrate a mathematical exercise to help the students apply their data to the cell. Ultimately, this assay sets the stage for future inquiry-based experiments, in which the students develop their own experimental questions and delve deeper into the mechanisms of phagocytosis and exocytosis.

  4. Ectocommensal and ectoparasites in goldfish Carassius auratus (Linnaeus, 1758 in farmed in the State of São Paulo

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    Carla Renata Serantoni Moyses

    Full Text Available Concomitant infections by several parasitic genera are rare, very debilitating and often lethal to fish reared under commercial breeding conditions. Were describe a multiple and concurrent parasite infestation in cultured goldfish Carassius auratus with skin damage (nodules and/or ulceration. Fish with skin lesions underwent necropsy, and the skin and gills were scraped and examined. Histopathological examination with Hematoxylin-Eosin and Giemsa stain, and an ultrastructure study using transmission and scanning electron microscopy were conducted. In the skin, we identified multiple-parasite infestations by Gyrodactylidae, Epistylis sp., Trichodina sp., Ichthyophthirius multifiliis, Tetrahymena sp. and Ichthyobodo necator,associated with epithelial cell hyperplasia and epidermal sloughing. Although no gross lesions were observed, were identified a large number of parasites in the gills (Epistylis sp., Piscinoodinium sp., Ichthyophthirius multifiliis, Trichodina sp., Apiosoma sp., Hexamitasp. and cysts of a trematode digenean. The observed trematodes were not identified. The associated microscopic lesions were epithelial hypertrophic and hyperplasic and exhibited fusion of secondary lamellae and epithelial cell detachment. This is the first description of a protozoan Vorticella sp. parasitizing goldfish in Brazil. Multiple ectoparasitism by protozoa and Platyhelminthes, with or without apparent tissue damage, can be fatal for goldfish raised on farms with poor management.

  5. Temporal regulation of foregut development by HTZ-1/H2A.Z and PHA-4/FoxA.

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    Dustin L Updike

    2006-09-01

    Full Text Available The histone variant H2A.Z is evolutionarily conserved and plays an essential role in mice, Drosophila, and Tetrahymena. The essential function of H2A.Z is unknown, with some studies suggesting a role in transcriptional repression and others in activation. Here we show that Caenorhabditis elegans HTZ-1/H2A.Z and the remodeling complex MYS-1/ESA1-SSL-1/SWR1 synergize with the FoxA transcription factor PHA-4 to coordinate temporal gene expression during foregut development. We observe dramatic genetic interactions between pha-4 and htz-1, mys-1, and ssl-1. A survey of transcription factors reveals that this interaction is specific, and thus pha-4 is acutely sensitive to reductions in these three proteins. Using a nuclear spot assay to visualize HTZ-1 in living embryos as organogenesis proceeds, we show that HTZ-1 is recruited to foregut promoters at the time of transcriptional onset, and this recruitment requires PHA-4. Loss of htz-1 by RNAi is lethal and leads to delayed expression of a subset of foregut genes. Thus, the effects of PHA-4 on temporal regulation can be explained in part by recruitment of HTZ-1 to target promoters. We suggest PHA-4 and HTZ-1 coordinate temporal gene expression by modulating the chromatin environment.

  6. Meiosis gene inventory of four ciliates reveals the prevalence of a synaptonemal complex-independent crossover pathway.

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    Chi, Jingyun; Mahé, Frédéric; Loidl, Josef; Logsdon, John; Dunthorn, Micah

    2014-03-01

    To establish which meiosis genes are present in ciliates, and to look for clues as to which recombination pathways may be treaded by them, four genomes were inventoried for 11 meiosis-specific and 40 meiosis-related genes. We found that the set of meiosis genes shared by Tetrahymena thermophila, Paramecium tetraurelia, Ichthyophthirius multifiliis, and Oxytricha trifallax is consistent with the prevalence of a Mus81-dependent class II crossover pathway that is considered secondary in most model eukaryotes. There is little evidence for a canonical class I crossover pathway that requires the formation of a synaptonemal complex (SC). This gene inventory suggests that meiotic processes in ciliates largely depend on mitotic repair proteins for executing meiotic recombination. We propose that class I crossovers and SCs were reduced sometime during the evolution of ciliates. Consistent with this reduction, we provide microscopic evidence for the presence only of degenerate SCs in Stylonychia mytilus. In addition, lower nonsynonymous to synonymous mutation rates of some of the meiosis genes suggest that, in contrast to most other nuclear genes analyzed so far, meiosis genes in ciliates are largely evolving at a slower rate than those genes in fungi and animals.

  7. Transposon Invasion of the Paramecium Germline Genome Countered by a Domesticated PiggyBac Transposase and the NHEJ Pathway

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    Emeline Dubois

    2012-01-01

    Full Text Available Sequences related to transposons constitute a large fraction of extant genomes, but insertions within coding sequences have generally not been tolerated during evolution. Thanks to their unique nuclear dimorphism and to their original mechanism of programmed DNA elimination from their somatic nucleus (macronucleus, ciliates are emerging model organisms for the study of the impact of transposable elements on genomes. The germline genome of the ciliate Paramecium, located in its micronucleus, contains thousands of short intervening sequences, the IESs, which interrupt 47% of genes. Recent data provided support to the hypothesis that an evolutionary link exists between Paramecium IESs and Tc1/mariner transposons. During development of the macronucleus, IESs are excised precisely thanks to the coordinated action of PiggyMac, a domesticated piggyBac transposase, and of the NHEJ double-strand break repair pathway. A PiggyMac homolog is also required for developmentally programmed DNA elimination in another ciliate, Tetrahymena. Here, we present an overview of the life cycle of these unicellular eukaryotes and of the developmentally programmed genome rearrangements that take place at each sexual cycle. We discuss how ancient domestication of a piggyBac transposase might have allowed Tc1/mariner elements to spread throughout the germline genome of Paramecium, without strong counterselection against insertion within genes.

  8. A two-locus molecular characterization of Paramecium calkinsi.

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    Przyboś, Ewa; Tarcz, Sebastian; Potekhin, Alexey; Rautian, Maria; Prajer, Małgorzata

    2012-03-01

    Paramecium calkinsi (Ciliophora, Protozoa) is a euryhaline species which was first identified in freshwater habitats, but subsequently several strains were also collected from brackish water. It is characterized by clockwise spiral swimming movement and the general morphology of the "bursaria type." The present paper is the first molecular characterization of P. calkinsi strains recently collected in distant regions in Russia using ITS1-5.8S- ITS2-5'LSU rDNA (1100bp) and COI (620bp) mtDNA sequenced gene fragments. For comparison, our molecular analysis includes P. bursaria, exhibiting a similar "bursaria morphotype" as well as species representing the "aurelia type," i.e., P. caudatum, P. multimicronucleatum, P. jenningsi, and P. schewiakoffi, and some species of the P. aurelia species complex (P. primaurelia, P. tetraurelia, P. sexaurelia, and P. tredecaurelia). We also use data from GenBank concerning other species in the genus Paramecium and Tetrahymena (which used as an outgroup). The division of the genus Paramecium into four subgenera (proposed by Fokin et al. 2004) is clearly presented by the trees. There is a clear separation between P. calkinsi strains collected from different regions (races). Consequently, given the molecular distances between them, it seems that these races may represent different syngens within the species. Copyright © 2011 Elsevier GmbH. All rights reserved.

  9. Coincidental loss of bacterial virulence in multi-enemy microbial communities.

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    Ji Zhang

    Full Text Available The coincidental virulence evolution hypothesis suggests that outside-host selection, such as predation, parasitism and resource competition can indirectly affect the virulence of environmentally-growing bacterial pathogens. While there are some examples of coincidental environmental selection for virulence, it is also possible that the resource acquisition and enemy defence is selecting against it. To test these ideas we conducted an evolutionary experiment by exposing the opportunistic pathogen bacterium Serratia marcescens to the particle-feeding ciliate Tetrahymena thermophila, the surface-feeding amoeba Acanthamoeba castellanii, and the lytic bacteriophage Semad11, in all possible combinations in a simulated pond water environment. After 8 weeks the virulence of the 384 evolved clones were quantified with fruit fly Drosophila melanogaster oral infection model, and several other life-history traits were measured. We found that in comparison to ancestor bacteria, evolutionary treatments reduced the virulence in most of the treatments, but this reduction was not clearly related to any changes in other life-history traits. This suggests that virulence traits do not evolve in close relation with these life-history traits, or that different traits might link to virulence in different selective environments, for example via resource allocation trade-offs.

  10. Predation and resource fluctuations drive eco-evolutionary dynamics of a bacterial community

    Science.gov (United States)

    Hiltunen, Teppo; Friman, Ville-Petri; Kaitala, Veijo; Mappes, Johanna; Laakso, Jouni

    2012-01-01

    Predation and temporal resource availability are among the most important factors determining prey community dynamics and composition. Both factors have been shown to affect prey diversity, but less is known about their interactive effects, especially in rapidly evolving prey communities. In a laboratory microcosm experiment, we manipulated the presence of the predatory protozoan Tetrahymena thermophila and the temporal patterns in the availability of resources for a bacterial prey community. We found that both predation and temporal fluctuations in prey resources resulted in a more even prey community, and these factors also interacted so that the effect of predation was only seen in a fluctuating environment. One possible explanation for this finding could be differences in prey species grazing resistance and resource use abilities, which likely had the greatest effect on prey community structure in fluctuating environments with periodical resource limitation. We also found that prey communities evolved to be more grazing-resistant during the experiment, and that this effect was due to a clear increase in the grazing resistance of the bacterium Serratia marcescens. Our results demonstrate that temporal variability in prey resources and predation can promote more even prey species proportions by allowing the existence of both defensive and competitive prey life-history strategies.

  11. Toxicity of five anilines to crustaceans, protozoa and bacteria

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    MARILIIS SIHTMÄE

    2010-09-01

    Full Text Available Aromatic amines (anilines and related derivates are an important class of environmental pollutants that can be released to the aquatic environment as industrial effluents or as breakdown products of pesticides and dyes. The toxicity of aniline, 2-chloroaniline, 3-chloroaniline, 4-chloroaniline and 3,5-dichloroaniline towards a multitrophic test battery comprised of bacteria Aliivibrio fischeri (formerly Vibrio fischeri, a ciliated protozoan Tetrahymena thermophila and two crustaceans (Daphnia magna and Thamnocephalus platyurus were investigated. Under the applied test conditions, the toxicity of the anilines notably varied among the test species. The bacteria and protozoa were much less sensitive towards the anilines than the crustaceans: EC50 values 13–403 mg L-1 versus 0.13–15.2 mg L-1. No general tendency between toxicity and the chemical structure of the anilines (the degree of chloro-substitution and the position of the chloro-substituents was found in the case of all the tested aquatic species. The replacement of the artificial test medium (ATM by the river water remarkably decreased the toxicity of anilines to crustaceans but not to protozoa. This research is part of the EU 6th Framework Integrated Project OSIRIS, in which ecotoxicogenomic studies of anilines (e.g., for Daphnia magna will also be performed that may help to clarify the mechanisms of toxicity of different anilines.

  12. Effects of chronic γ-irradiation on the aquatic microbial microcosm: equi-dosimetric comparison with effects of heavy metals.

    Science.gov (United States)

    Fuma, Shoichi; Kawaguchi, Isao; Kubota, Yoshihisa; Yoshida, Satoshi; Kawabata, Zen'ichiro; Polikarpov, Gennady G

    2012-02-01

    Effects of chronic γ-irradiation were investigated in the aquatic microcosm consisting of flagellate algae Euglena gracilis as producers, ciliate protozoa Tetrahymena thermophila as consumers and bacteria Escherichia coli as decomposers. At 1.1 Gy day(-1), no effects were observed. At 5.1 Gy day(-1), cell densities of E. coli showed a tendency to be lower than those of controls. At 9.7 and 24.7 Gy day(-1), population decrease was observed in E. coli. E. gracilis and T. thermophila died out after temporal population decrease and subsequent population increase in T. thermophila. It is likely that this temporal population increase was an indirect effect due to interspecies interactions. Effect dose rates of γ-rays were compared with effect concentrations of some metals using the radiochemoecological conceptual model and the effect index for microcosm. Comparison of these community-level effects data with environmental exposure data suggests that ionising radiation, gadolinium and dysprosium have low risks to affect aquatic microbial communities while manganese, nickel and copper have considerable risks. Effects of chronic irradiation were smaller than those of acute irradiation, and an acute to chronic ratio was calculated to be 28 by dividing an acute dose by chronic daily dose rate at which the effect index was 10%. This ratio would be useful for community-level extrapolation from acute to chronic radiation effects. Copyright © 2011 Elsevier Ltd. All rights reserved.

  13. Fine oral filaments in Paramecium: a biochemical and immunological analysis.

    Science.gov (United States)

    Clerot, J; Iftode, F; Budin, K; Jeanmaire-Wolf, R; Coffe, G; Fleury-Aubusson, A

    2001-01-01

    In Paramecium, several kinds of the oral networks of fine filaments are defined at the ultrastructural level. Using the sodium chloride-treated oral apparatus of Paramecium as an antigen to produce monoclonal antibodies, we have begun to identify the proteins constituting these networks. Immunoblotting showed that all positive antibodies were directed against three bands (70-, 75-and 83-kD), which corresponded to quantitatively minor components of the antigen; there was no antibody specific for the quantitatively major components (58- and 62-kD). Immunolocalization with four of these antibodies directed against one or several of these three bands showed that these proteins are components of the fine filaments supporting the oral area; a decoration of the basal bodies and the outer lattice was also observed on the cortex. Immunofluorescence on interphase cells suggested that the three proteins colocalized on the left side of the oral apparatus, whereas only the 70-kD band was detected on the right side. During division, the antigens of the antibodies were detected at different stages after oral basal body assembly. The antibodies cross-reacted with the tetrins, which are oral filament-forming proteins in Tetrahymena, demonstrating that tetrin-related proteins are quantitatively minor components of the oral and the somatic cytoskeleton of Paramecium.

  14. The membrane skeleton in Paramecium: Molecular characterization of a novel epiplasmin family and preliminary GFP expression results.

    Science.gov (United States)

    Pomel, Sébastien; Diogon, Marie; Bouchard, Philippe; Pradel, Lydie; Ravet, Viviane; Coffe, Gérard; Viguès, Bernard

    2006-02-01

    Previous attempts to identify the membrane skeleton of Paramecium cells have revealed a protein pattern that is both complex and specific. The most prominent structural elements, epiplasmic scales, are centered around ciliary units and are closely apposed to the cytoplasmic side of the inner alveolar membrane. We sought to characterize epiplasmic scale proteins (epiplasmins) at the molecular level. PCR approaches enabled the cloning and sequencing of two closely related genes by amplifications of sequences from a macronuclear genomic library. Using these two genes (EPI-1 and EPI-2), we have contributed to the annotation of the Paramecium tetraurelia macronuclear genome and identified 39 additional (paralogous) sequences. Two orthologous sequences were found in the Tetrahymena thermophila genome. Structural analysis of the 43 sequences indicates that the hallmark of this new multigenic family is a 79 aa domain flanked by two Q-, P- and V-rich stretches of sequence that are much more variable in amino-acid composition. Such features clearly distinguish members of the multigenic family from epiplasmic proteins previously sequenced in other ciliates. The expression of Green Fluorescent Protein (GFP)-tagged epiplasmin showed significant labeling of epiplasmic scales as well as oral structures. We expect that the GFP construct described herein will prove to be a useful tool for comparative subcellular localization of different putative epiplasmins in Paramecium.

  15. Phylogenetic analysis of the Neks reveals early diversification of ciliary-cell cycle kinases.

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    Jeremy D K Parker

    2007-10-01

    Full Text Available NIMA-related kinases (Neks have been studied in diverse eukaryotes, including the fungus Aspergillus and the ciliate Tetrahymena. In the former, a single Nek plays an essential role in cell cycle regulation; in the latter, which has more than 30 Neks in its genome, multiple Neks regulate ciliary length. Mammalian genomes encode an intermediate number of Neks, several of which are reported to play roles in cell cycle regulation and/or localize to centrosomes. Previously, we reported that organisms with cilia typically have more Neks than organisms without cilia, but were unable to establish the evolutionary history of the gene family.We have performed a large-scale analysis of the Nek family using Bayesian techniques, including tests of alternate topologies. We find that the Nek family had already expanded in the last common ancestor of eukaryotes, a ciliated cell which likely expressed at least five Neks. We suggest that Neks played an important role in the common ancestor in regulating cilia, centrioles, and centrosomes with respect to mitotic entry, and that this role continues today in organisms with cilia. Organisms that lack cilia generally show a reduction in the number of Nek clades represented, sometimes associated with lineage specific expansion of a single clade, as has occurred in the plants.This is the first rigorous phylogenetic analysis of a kinase family across a broad array of phyla. Our findings provide a coherent framework for the study of Neks and their roles in coordinating cilia and cell cycle progression.

  16. New insights into myosin evolution and classification.

    Science.gov (United States)

    Foth, Bernardo J; Goedecke, Marc C; Soldati, Dominique

    2006-03-07

    Myosins are eukaryotic actin-dependent molecular motors important for a broad range of functions like muscle contraction, vision, hearing, cell motility, and host cell invasion of apicomplexan parasites. Myosin heavy chains consist of distinct head, neck, and tail domains and have previously been categorized into 18 different classes based on phylogenetic analysis of their conserved heads. Here we describe a comprehensive phylogenetic examination of many previously unclassified myosins, with particular emphasis on sequences from apicomplexan and other chromalveolate protists including the model organism Toxoplasma, the malaria parasite Plasmodium, and the ciliate Tetrahymena. Using different phylogenetic inference methods and taking protein domain architectures, specific amino acid polymorphisms, and organismal distribution into account, we demonstrate a hitherto unrecognized common origin for ciliate and apicomplexan class XIV myosins. Our data also suggest common origins for some apicomplexan myosins and class VI, for classes II and XVIII, for classes XII and XV, and for some microsporidian myosins and class V, thereby reconciling evolutionary history and myosin structure in several cases and corroborating the common coevolution of myosin head, neck, and tail domains. Six novel myosin classes are established to accommodate sequences from chordate metazoans (class XIX), insects (class XX), kinetoplastids (class XXI), and apicomplexans and diatom algae (classes XXII, XXIII, and XXIV). These myosin (sub)classes include sequences with protein domains (FYVE, WW, UBA, ATS1-like, and WD40) previously unknown to be associated with myosin motors. Regarding the apicomplexan "myosome," we significantly update class XIV classification, propose a systematic naming convention, and discuss possible functions in these parasites.

  17. The Macronuclear Genome of Stentor coeruleus Reveals Tiny Introns in a Giant Cell.

    Science.gov (United States)

    Slabodnick, Mark M; Ruby, J Graham; Reiff, Sarah B; Swart, Estienne C; Gosai, Sager; Prabakaran, Sudhakaran; Witkowska, Ewa; Larue, Graham E; Fisher, Susan; Freeman, Robert M; Gunawardena, Jeremy; Chu, William; Stover, Naomi A; Gregory, Brian D; Nowacki, Mariusz; Derisi, Joseph; Roy, Scott W; Marshall, Wallace F; Sood, Pranidhi

    2017-02-20

    The giant, single-celled organism Stentor coeruleus has a long history as a model system for studying pattern formation and regeneration in single cells. Stentor [1, 2] is a heterotrichous ciliate distantly related to familiar ciliate models, such as Tetrahymena or Paramecium. The primary distinguishing feature of Stentor is its incredible size: a single cell is 1 mm long. Early developmental biologists, including T.H. Morgan [3], were attracted to the system because of its regenerative abilities-if large portions of a cell are surgically removed, the remnant reorganizes into a normal-looking but smaller cell with correct proportionality [2, 3]. These biologists were also drawn to Stentor because it exhibits a rich repertoire of behaviors, including light avoidance, mechanosensitive contraction, food selection, and even the ability to habituate to touch, a simple form of learning usually seen in higher organisms [4]. While early microsurgical approaches demonstrated a startling array of regenerative and morphogenetic processes in this single-celled organism, Stentor was never developed as a molecular model system. We report the sequencing of the Stentor coeruleus macronuclear genome and reveal key features of the genome. First, we find that Stentor uses the standard genetic code, suggesting that ciliate-specific genetic codes arose after Stentor branched from other ciliates. We also discover that ploidy correlates with Stentor's cell size. Finally, in the Stentor genome, we discover the smallest spliceosomal introns reported for any species. The sequenced genome opens the door to molecular analysis of single-cell regeneration in Stentor. Copyright © 2017 The Authors. Published by Elsevier Ltd.. All rights reserved.

  18. A nucleotide-independent cyclic nitroxide label for monitoring segmental motions in nucleic acids.

    Science.gov (United States)

    Nguyen, Phuong H; Popova, Anna M; Hideg, Kálmán; Qin, Peter Z

    2015-01-01

    Spin labels, which are chemically stable radicals attached at specific sites of a bio-molecule, enable investigations on structure and dynamics of proteins and nucleic acids using techniques such as site-directed spin labeling and paramagnetic NMR. Among spin labels developed, the class of rigid labels have limited or no independent motions between the radical bearing moiety and the target, and afford a number of advantages in measuring distances and monitoring local dynamics within the parent bio-molecule. However, a general method for attaching a rigid label to nucleic acids in a nucleotide-independent manner has not been reported. We developed an approach for installing a nearly rigid nitroxide spin label, designated as R5c, at a specific site of the nucleic acid backbone in a nucleotide-independent manner. The method uses a post-synthesis approach to covalently attach the nitroxide moiety in a cyclic fashion to phosphorothioate groups introduced at two consecutive nucleotides of the target strand. R5c-labeled nucleic acids are capable of pairing with their respective complementary strands, and the cyclic nature of R5c attachment significantly reduced independence motions of the label with respect to the parent duplex, although it may cause distortion of the local environment at the site of labeling. R5c yields enhanced sensitivity to the collective motions of the duplex, as demonstrated by its capability to reveal changes in collective motions of the substrate recognition duplex of the 120-kDa Tetrahymena group I ribozyme, which elude detection by a flexible label. The cyclic R5c nitroxide can be efficiently attached to a target nucleic acid site using a post-synthetic coupling approach conducted under mild biochemical conditions, and serves as a viable label for experimental investigation of segmental motions in nucleic acids, including large folded RNAs.

  19. Mutagenesis of tGCN5 core region reveals two critical surface residues F90 and R140

    Energy Technology Data Exchange (ETDEWEB)

    Mehta, Kinjal Rajesh; Chan, Yan M.; Lee, Man X.; Yang, Ching Yao; Voloshchuk, Natalya [Department of Chemical and Biological Sciences, Polytechnic Institute of New York University, 6 MetroTech Center, Brooklyn, NY 11201 (United States); Montclare, Jin Kim, E-mail: jmontcla@poly.edu [Department of Chemical and Biological Sciences, Polytechnic Institute of New York University, 6 MetroTech Center, Brooklyn, NY 11201 (United States); Department of Biochemistry, SUNY-Downstate Medical Center, 450 Clarkson Avenue, Brooklyn, NY 11203 (United States)

    2010-09-24

    Research highlights: {yields} Mutagenesis of the tGCN5 core region reveals two residues important for function. {yields} Developed a fluorescent lysate-based activity assay to assess mutants. {yields} Surface-exposed residues F90 and R140 of tGCN5 are critical for H3 acetylation. -- Abstract: Tetrahymena General Control Non-Derepressor 5 (tGCN5) is a critical regulator of gene transcription via acetylation of histones. Since the acetylation ability has been attributed to the 'core region', we perform mutagenesis of residues within the tGCN5 'core region' in order to identify those critical for function and stability. Residues that do not participate in catalysis are identified, mutated and characterized for activity, structure and thermodynamic stability. Variants I107V, Q114L, A121T and A130S maintain the acetylation function relative to wild-type tGCN5, while variants F90Y, F112R and R140H completely abolish function. Of the three non-functional variants, since F112 is mutated into a non-homologous charged residue, a loss in function is expected. However, the remaining two variants are mutated into homologous residues, suggesting that F90 and R140 are critical for the activity of tGCN5. While mutation to homologous residue maintains acetylation of histone H3 for the majority of the variants, the two surface-exposed residues, F90 and R140, appear to be essential for tGCN5 function, structure or stability.

  20. Monitoring equilibrium changes in RNA structure by 'peroxidative' and 'oxidative' hydroxyl radical footprinting.

    Science.gov (United States)

    Bachu, Ravichandra; Padlan, Frances-Camille S; Rouhanifard, Sara; Brenowitz, Michael; Schlatterer, Jörg C

    2011-10-17

    RNA molecules play an essential role in biology. In addition to transmitting genetic information, RNA can fold into unique tertiary structures fulfilling a specific biologic role as regulator, binder or catalyst. Information about tertiary contact formation is essential to understand the function of RNA molecules. Hydroxyl radicals (•OH) are unique probes of the structure of nucleic acids due to their high reactivity and small size. When used as a footprinting probe, hydroxyl radicals map the solvent accessible surface of the phosphodiester backbone of DNA and RNA with as fine as single nucleotide resolution. Hydroxyl radical footprinting can be used to identify the nucleotides within an intermolecular contact surface, e.g. in DNA-protein and RNA-protein complexes. Equilibrium and kinetic transitions can be determined by conducting hydroxyl radical footprinting as a function of a solution variable or time, respectively. A key feature of footprinting is that limited exposure to the probe (e.g., 'single-hit kinetics') results in the uniform sampling of each nucleotide of the polymer. In this video article, we use the P4-P6 domain of the Tetrahymena ribozyme to illustrate RNA sample preparation and the determination of a Mg(II)-mediated folding isotherms. We describe the use of the well known hydroxyl radical footprinting protocol that requires H(2)O(2) (we call this the 'peroxidative' protocol) and a valuable, but not widely known, alternative that uses naturally dissolved O(2)(we call this the 'oxidative' protocol). An overview of the data reduction, transformation and analysis procedures is presented.

  1. A highly conserved Poc1 protein characterized in embryos of the hydrozoan Clytia hemisphaerica: localization and functional studies.

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    Cécile Fourrage

    Full Text Available Poc1 (Protein of Centriole 1 proteins are highly conserved WD40 domain-containing centriole components, well characterized in the alga Chlamydomonas, the ciliated protazoan Tetrahymena, the insect Drosophila and in vertebrate cells including Xenopus and zebrafish embryos. Functions and localizations related to the centriole and ciliary axoneme have been demonstrated for Poc1 in a range of species. The vertebrate Poc1 protein has also been reported to show an additional association with mitochondria, including enrichment in the specialized "germ plasm" region of Xenopus oocytes. We have identified and characterized a highly conserved Poc1 protein in the cnidarian Clytia hemisphaerica. Clytia Poc1 mRNA was found to be strongly expressed in eggs and early embryos, showing a punctate perinuclear localization in young oocytes. Fluorescence-tagged Poc1 proteins expressed in developing embryos showed strong localization to centrioles, including basal bodies. Anti-human Poc1 antibodies decorated mitochondria in Clytia, as reported in human cells, but failed to recognise endogenous or fluorescent-tagged Clytia Poc1. Injection of specific morpholino oligonucleotides into Clytia eggs prior to fertilization to repress Poc1 mRNA translation interfered with cell division from the blastula stage, likely corresponding to when neosynthesis normally takes over from maternally supplied protein. Cell cycle lengthening and arrest were observed, phenotypes consistent with an impaired centriolar biogenesis or function. The specificity of the defects could be demonstrated by injection of synthetic Poc1 mRNA, which restored normal development. We conclude that in Clytia embryos, Poc1 has an essentially centriolar localization and function.

  2. Structure of the 40S ribosomal subunit of Plasmodium falciparum by homology and de novo modeling

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    Harrison Ndung'u Mwangi

    2017-01-01

    Full Text Available Generation of three dimensional structures of macromolecules using in silico structural modeling technologies such as homology and de novo modeling has improved dramatically and increased the speed by which tertiary structures of organisms can be generated. This is especially the case if a homologous crystal structure is already available. High-resolution structures can be rapidly created using only their sequence information as input, a process that has the potential to increase the speed of scientific discovery. In this study, homology modeling and structure prediction tools such as RNA123 and SWISS–MODEL were used to generate the 40S ribosomal subunit from Plasmodium falciparum. This structure was modeled using the published crystal structure from Tetrahymena thermophila, a homologous eukaryote. In the absence of the Plasmodium falciparum 40S ribosomal crystal structure, the model accurately depicts a global topology, secondary and tertiary connections, and gives an overall root mean square deviation (RMSD value of 3.9 Å relative to the template׳s crystal structure. Deviations are somewhat larger in areas with no homology between the templates. These results demonstrate that this approach has the power to identify motifs of interest in RNA and identify potential drug targets for macromolecules whose crystal structures are unknown. The results also show the utility of RNA homology modeling software for structure determination and lay the groundwork for applying this approach to larger and more complex eukaryotic ribosomes and other RNA-protein complexes. Structures generated from this study can be used in in silico screening experiments and lead to the determination of structures for targets/hit complexes.

  3. Health effects research in direct coal liquefaction. Studies of H-coal distillates: Phase I. PDU samples - the effects of hydrotreatment

    Energy Technology Data Exchange (ETDEWEB)

    Epler, J.L.; Fry, R.J.M.; Larimer, F.W.

    1981-11-01

    A multi-divisional effort aimed at the integrated assessment of the health and environmental effects of various coal conversion and shale oil technologies is being carried out. The feasibility of using health effects bioassays to predict the potential biohazard of various H-Coal derived test materials is examined in a coupled chemical and biological approach. The primary focus of the research is the use of preliminary chemical characterizations and preparation for bioassay, followed by testing in short-term assays in order to rapidly ascertain the potential biohazard. Mammalian toxicological assays parallel the testing. Raw and hydrotreated product liquids from process development units of H-Coal and the pilot plant solvent refined coal process were examined for acute toxicity monitored as population growth impairment of Tetrahymena exposed to aqueous extracts and for mutagenic activity monitored as revertants of Salmonella exposed to metabolically activated chemical class fractions. Medium to high severity hydrotreatment appears to be an effective means of reducing biological activity, presumably by reducing the aromaticity and heteroatom content. Five basic mammalian, acute toxicity tests have been conducted with selected H-coal samples and shale oil derivatives. The data show that H-Coal samples are moderately toxic whereas the toxicity of shale oil derived products is slight and comparable to samples obtained from naturally occurring petroleums. No overt skin or eye toxicity was found. The present data reveal that coal-derived distillates generated by the H-coal process are highly carcinogenic to mouse skin. An extreme form of neurotoxicity associated with dermal exposure to one of the lighter, minimally carcinogenic, materials was noted. (DMC)

  4. Ciprofloxacin residue and antibiotic-resistant biofilm bacteria in hospital effluent.

    Science.gov (United States)

    Ory, Jérôme; Bricheux, Geneviève; Togola, Anne; Bonnet, Jean Louis; Donnadieu-Bernard, Florence; Nakusi, Laurence; Forestier, Christiane; Traore, Ousmane

    2016-07-01

    Discharge of antimicrobial residues and resistant bacteria in hospital effluents is supposed to have strong impacts on the spread of antibiotic resistant bacteria in the environment. This study aimed to characterize the effluents of the Gabriel Montpied teaching hospital, Clermont-Ferrand, France, by simultaneously measuring the concentration of ciprofloxacin and of biological indicators resistant to this molecule in biofilms formed in the hospital effluent and by comparing these data to ciprofloxacin consumption and resistant bacterial isolates of the hospital. Determination of the measured environmental concentration of ciprofloxacin by spot sampling and polar organic chemical integrative (POCIS) sampling over 2 weeks, and comparison with predicted environmental concentrations produced a hazard quotient >1, indicating a potential ecotoxicological risk. A negative impact was also observed with whole hospital effluent samples using the Tetrahymena pyriformis biological model. During the same period, biofilms were formed within the hospital effluent, and analysis of ciprofloxacin-resistant isolates indicated that Gamma-Proteobacteria were numerous, predominantly Aeromonadaceae (69.56%) and Enterobacteriaceae (22.61%). Among the 115 isolates collected, plasmid-mediated fluoroquinolone-resistant genes were detected, with mostly aac(6')-lb-cr and qnrS. In addition, 60% of the isolates were resistant to up to six antibiotics, including molecules mostly used in the hospital (aminosides and third-generation cephalosporins). In parallel, 1247 bacteria isolated from hospitalized patients and resistant to at least one of the fluoroquinolones were collected. Only 5 of the 14 species identified in the effluent biofilm were also found in the clinical isolates, but PFGE typing of the Gram-negative isolates found in both compartments showed there was no clonality among the strains. Altogether, these data confirm the role of hospital loads as sources of pollution for wastewater

  5. RNA folding and catalysis mediated by iron (II.

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    Shreyas S Athavale

    Full Text Available Mg²⁺ shares a distinctive relationship with RNA, playing important and specific roles in the folding and function of essentially all large RNAs. Here we use theory and experiment to evaluate Fe²⁺ in the absence of free oxygen as a replacement for Mg²⁺ in RNA folding and catalysis. We describe both quantum mechanical calculations and experiments that suggest that the roles of Mg²⁺ in RNA folding and function can indeed be served by Fe²⁺. The results of quantum mechanical calculations show that the geometry of coordination of Fe²⁺ by RNA phosphates is similar to that of Mg²⁺. Chemical footprinting experiments suggest that the conformation of the Tetrahymena thermophila Group I intron P4-P6 domain RNA is conserved between complexes with Fe²⁺ or Mg²⁺. The catalytic activities of both the L1 ribozyme ligase, obtained previously by in vitro selection in the presence of Mg²⁺, and the hammerhead ribozyme are enhanced in the presence of Fe²⁺ compared to Mg²⁺. All chemical footprinting and ribozyme assays in the presence of Fe²⁺ were performed under anaerobic conditions. The primary motivation of this work is to understand RNA in plausible early earth conditions. Life originated during the early Archean Eon, characterized by a non-oxidative atmosphere and abundant soluble Fe²⁺. The combined biochemical and paleogeological data are consistent with a role for Fe²⁺ in an RNA World. RNA and Fe²⁺ could, in principle, support an array of RNA structures and catalytic functions more diverse than RNA with Mg²⁺ alone.

  6. Ions and RNAs: Free Energies of Counterion-Mediated RNA Fold Stabilities.

    Science.gov (United States)

    Mak, C H; Henke, Paul S

    2013-01-08

    We present an implicit ion model fo the calculation of the electrostatic free energies of RNA conformations in the presence of divalent counterions such as Mg(2+). The model was applied to the native and several non-native structures of the hammerhead ribozyme and the group I intron in Tetrahymena to study the stability of candidate unfolding intermediates. Based on a rigorous statistical mechanical treatment of the counterions that are closely associated with the RNA while handling the rest of the ions in the solution via a mean field theory in the Grand Canonical ensemble, the implicit ion model accurately reproduces the ordering of their free energies, correctly identifying the native fold as the most stable structure out of the other alternatives. For RNA concentrations in the range below 0.1 μM, divalent concentrations of ∼0.5 mM or above, and over a wide range of solvent dielectric constants, the equilibrium number of divalent ions associated with the RNA remains close to what is needed to exactly neutralize the phosphate negative charges, but the stability of compact RNA folds can be reversed when the divalent ion concentration is lower than ∼0.1 mM, causing the number of associated ions to underneutralize the RNA. In addition to calculating counterion-mediated free energies, the model is also able to identify potential high-affinity electronegative ion binding pockets on the RNA. The model can be easily integrated into an all-atom Monte Carlo RNA simulation as an implicit counterion model.

  7. Physicochemical and toxicological studies on 4-chloro-3,5-dinitrobenzoic acid in aqueous solutions.

    Science.gov (United States)

    Lopez, Jorge L; García Einschlag, Fernando S; Rives, Carina V; Villata, Laura S; Capparelli, Alberto L

    2004-05-01

    Physicochemical characterization of hazardous compounds often is required for the development of structure-reactivity correlations. Physical, chemical, and toxicological properties of target pollutants require determination for an efficient application of wastewater treatments. In the present work, we chose a chloro-nitro-aromatic derivative (4-chloro-3,5-dinitrobenzoic acid [CDNBA]), as a model compound on which to perform physicochemical and toxicological studies. Several properties of CDNBA are not available in the literature, although many aromatic nitro-compounds are considered hazardous materials. Measurements of solubility in water, acid dissociation constant, and kinetic parameters for the nucleophilic substitution of chlorine atom in alkaline media are reported. We also performed cytotoxicity studies of CDNBA and ultraviolet-irradiated CDNBA solutions. From the analysis of CDNBA solubility in water at different temperatures, an enthalpy of solution of 23.2 +/- 2.5 kJ/mol was found. The study of the acid dissociation constant Kc by using conductivity measurements and the modified Gran's method yielded values for the equilibrium constant Ka of 2.36 x 10(-3) and 2.26 x 10(-3), respectively. The bimolecular rate constant for the reaction of CDNB- and hydroxyl ion (HO) measured at room temperature and 0.1 M of ionic strength was 5.92/M x s, and the activation energy for this process was 70.7 +/- 3.4 kJ/mol. Cytotoxicity assays with aqueous suspensions of Tetrahymena pyriformis showed lethal effects due to the pH change induced by CDNBA. On the other hand, in buffered solutions, a value of 104.47 microM was observed for the median effective concentration, that is, the concentration of CDNBA at which the proliferation was restricted to one half of the blank. Irradiation of CDNBA solutions increased the toxicity, suggesting the formation of intermediate products with higher cytotoxicity effects.

  8. Hormones in the immune system and their possible role. A critical review.

    Science.gov (United States)

    Csaba, György

    2014-09-01

    Immune cells synthesize, store and secrete hormones, which are identical with the hormones of the endocrine glands. These are: the POMC hormones (ACTH, endorphin), the thyroid system hormones (TRH, TSH, T3), growth hormone (GH), prolactin, melatonin, histamine, serotonin, catecholamines, GnRH, LHRH, hCG, renin, VIP, ANG II. This means that the immune cells contain all of the hormones, which were searched at all and they also have receptors for these hormones. From this point of view the immune cells are similar to the unicells (Tetrahymena), so it can be supposed that these cells retained the properties characteristic at a low level of phylogeny while other cells during the evolution accumulated to form endocrine glands. In contrast to the glandular endocrine cells, immune cells are polyproducers and polyreceivers. As they are mobile cells, they are able to transport the stored hormone to different places (packed transport) or attracted by local factors, accumulate in the neighborhood of the target, synthesizing and secreting hormones locally. This is taking place, e.g. in the case of endorphin, where the accumulating immune cells calms pain caused by the inflammation. The targeted packed transport is more economical than the hormone-pouring to the blood circulation of glandular endocrines and the targeting also cares the other receptor-bearing cells timely not needed the effect. Mostly the immune-effects of immune-cell derived hormones were studied (except endorphin), however, it is not exactly cleared, while the system could have scarcely studied important roles in other cases. The evolutionary aspects and the known as well, as possible roles of immune-endocrine system and their hormones are listed and discussed.

  9. Comparative cytotoxicity and accumulation of Roxarsone and its photodegradates in freshwater Protozoan Tetrahymenathermophila

    Energy Technology Data Exchange (ETDEWEB)

    Zhang, Wenzhong; Xu, Fang, E-mail: fang.xu.zh@gmail.com; Han, Jingjing; Sun, Qun; Yang, Kai

    2015-04-09

    Highlights: • Released roxarsone (ROX) readily photolyzed into iAs{sup III}/iAs{sup V} bearing derivatives. • Clear cytotoxicity by ROX photodegradates but not by ROX in Tetrahymena cell. • As uptake in cell membrane by ROX exposure but in cytoplasm by ROX photodegradates. • Biomimetic membrane structure for assessing membrane permeability and cytotoxicity. • ROX photodegradates exposure associated intracellular 15 protein over expression. - Abstract: Roxarsone (ROX) remains to be as an organoarsenical feed additive used widely in developing countries. However, most of the ROX is excreted unchanged in manure, which could be readily photodegraded into inorganic arsenic derivatives. In this study, the comparative cytotoxicity and arsenic accumulation were evaluated after the exposure of Tetrahymenathermophila (T. thermophila) cell model to ROX and its photodegradates. The cytotoxic effects were estimated according to the relevant cell growth curves, morphologies and MTT assays. The 36 h median effective concentrations for ROX and its photodegradates at various photolysis times (10, 20, and 30 min) are 39.0, 2.08, 1.88, and 1.82 mg (total arsenic) L{sup −1}, respectively. In parallel, the cellular arsenic uptakes were determined by hydride generation-atomic fluorescence spectrometry. Phospholipid layer as basic membrane structure was mimicked to assess the correlation between membrane permeability and cytotoxicity. The biocompatibility of ROX was dependent on its tendency to interact with cell membrane while the cytotoxicity was induced by the trans-membrane of the inorganic arsenic species present in the photodegradates of ROX. Furthermore, the photodegradates of ROX-associated alterations of intracellular protein profiles were analyzed using a proteomic approach. Overall, the significance was clarified that the control of arsenic emission caused by the application of ROX needs to be imposed.

  10. Inhibition of the Rumen Ciliate Entodinium caudatum by Antibiotics.

    Science.gov (United States)

    Park, Tansol; Meulia, Tea; Firkins, Jeffrey L; Yu, Zhongtang

    2017-01-01

    Axenic cultures of free-living aerobic ciliates, such as Tetrahymena thermophila and Paramecium aurelia, have been established and routinely used in laboratory research, greatly facilitating, or enabling characterization of their metabolism, physiology, and ecology. Ruminal protozoa are anaerobic ciliates, and they play important roles in feed digestion and fermentation. Although, repeatedly attempted, no laboratory-maintainable axenic culture of ruminal ciliates has been established. When axenic ciliate cultures are developed, antibiotics are required to eliminate the accompanying bacteria. Ruminal ciliates gradually lose viability upon antibiotic treatments, and the resultant axenic cultures can only last for short periods of time. The objective of this study was to evaluate eight antibiotics that have been evaluated in developing axenic cultures of ruminal ciliates, for their toxicity to Entodinium caudatum, which is the most predominant ruminal ciliate species. Scanning and transmission electron microscopy (TEM) showed that the antibiotics damaged both the cell surface and nuclei of E. caudatum and increased accumulation of intracellular glycogen. Combinations of the three least toxic antibiotics failed to eliminate the bacteria that are present in the E. caudatum culture. The combination of ampicillin, carbenicillin, streptomycin, and oxytetracycline was able to eliminate all the bacteria, but the resultant axenic E. caudatum culture gradually lost viability. Adding the bacterial fraction (live) separated from an untreated E. caudatum culture reversed the viability decline and recovered the growth of the treated E. caudatum culture, whereas feeding nine strains of live bacteria isolated from E. caudatum cells, either individually or in combination, could not. Nutritional and metabolic dependence on its associated bacteria, accompanied with direct and indirect inhibition by antibiotics, makes it difficult to establish an axenic culture of E. caudatum. Monoxenic

  11. Protozoan Predation of Escherichia coli O157:H7 Is Unaffected by the Carriage of Shiga Toxin-Encoding Bacteriophages.

    Directory of Open Access Journals (Sweden)

    Carrie E Schmidt

    Full Text Available Escherichia coli O157:H7 is a food-borne bacterium that causes hemorrhagic diarrhea and hemolytic uremic syndrome in humans. While cattle are a known source of E. coli O157:H7 exposure resulting in human infection, environmental reservoirs may also be important sources of infection for both cattle and humans. Bacteriophage-encoded Shiga toxins (Stx carried by E. coli O157:H7 may provide a selective advantage for survival of these bacteria in the environment, possibly through their toxic effects on grazing protozoa. To determine Stx effects on protozoan grazing, we co-cultured Paramecium caudatum, a common ciliate protozoon in cattle water sources, with multiple strains of Shiga-toxigenic E. coli O157:H7 and non-Shiga toxigenic cattle commensal E. coli. Over three days at ambient laboratory temperature, P. caudatum consistently reduced both E. coli O157:H7 and non-Shiga toxigenic E. coli populations by 1-3 log cfu. Furthermore, a wild-type strain of Shiga-toxigenic E. coli O157:H7 (EDL933 and isogenic mutants lacking the A subunit of Stx 2a, the entire Stx 2a-encoding bacteriophage, and/or the entire Stx 1-encoding bacteriophage were grazed with similar efficacy by both P. caudatum and Tetrahymena pyriformis (another ciliate protozoon. Therefore, our data provided no evidence of a protective effect of either Stx or the products of other bacteriophage genes on protozoan predation of E. coli. Further research is necessary to determine if the grazing activity of naturally-occurring protozoa in cattle water troughs can serve to decrease cattle exposure to E. coli O157:H7 and other Shiga-toxigenic E. coli.

  12. Inhibition of the Rumen Ciliate Entodinium caudatum by Antibiotics

    Directory of Open Access Journals (Sweden)

    Tansol Park

    2017-06-01

    Full Text Available Axenic cultures of free-living aerobic ciliates, such as Tetrahymena thermophila and Paramecium aurelia, have been established and routinely used in laboratory research, greatly facilitating, or enabling characterization of their metabolism, physiology, and ecology. Ruminal protozoa are anaerobic ciliates, and they play important roles in feed digestion and fermentation. Although, repeatedly attempted, no laboratory-maintainable axenic culture of ruminal ciliates has been established. When axenic ciliate cultures are developed, antibiotics are required to eliminate the accompanying bacteria. Ruminal ciliates gradually lose viability upon antibiotic treatments, and the resultant axenic cultures can only last for short periods of time. The objective of this study was to evaluate eight antibiotics that have been evaluated in developing axenic cultures of ruminal ciliates, for their toxicity to Entodinium caudatum, which is the most predominant ruminal ciliate species. Scanning and transmission electron microscopy (TEM showed that the antibiotics damaged both the cell surface and nuclei of E. caudatum and increased accumulation of intracellular glycogen. Combinations of the three least toxic antibiotics failed to eliminate the bacteria that are present in the E. caudatum culture. The combination of ampicillin, carbenicillin, streptomycin, and oxytetracycline was able to eliminate all the bacteria, but the resultant axenic E. caudatum culture gradually lost viability. Adding the bacterial fraction (live separated from an untreated E. caudatum culture reversed the viability decline and recovered the growth of the treated E. caudatum culture, whereas feeding nine strains of live bacteria isolated from E. caudatum cells, either individually or in combination, could not. Nutritional and metabolic dependence on its associated bacteria, accompanied with direct and indirect inhibition by antibiotics, makes it difficult to establish an axenic culture of E

  13. Variability in secondary structure of 18S ribosomal RNA as topological marker for identification of Paramecium species.

    Science.gov (United States)

    Shakoori, Farah R; Tasneem, Fareeda; Al-Ghanim, K; Mahboob, S; Al-Misned, F; Jahan, Nusrat; Shakoori, Abdul Rauf

    2014-12-01

    Besides cytological and molecular applications, Paramecium is being used in water quality assessment and for determination of saprobic levels. An unambiguous identification of these unicellular eukaryotes is not only essential, but its ecological diversity must also be explored in the local environment. 18SrRNA genes of all the strains of Paramecium species isolated from waste water were amplified, cloned and sequenced. Phylogenetic comparison of the nucleotide sequences of these strains with 23 closely related Paramecium species from GenBank Database enabled identification of Paramecium multimicronucleatum and Paramecium jenningsi. Some isolates did not show significant close association with other Paramecium species, and because of their unique position in the phylogenetic tree, they were considered new to the field. In the present report, these isolates are being designated as Paramecium caudatum pakistanicus. In this article, secondary structure of 18SrRNA has also been analyzed as an additional and perhaps more reliable topological marker for species discrimination and for determining possible phylogenetic relationship between the ciliate species. On the basis of comparison of secondary structure of 18SrRNA of various isolated Paramacium strains, and among Paramecium caudatum pakistanicus, Tetrahymena thermophila, Drosophila melanogaster, and Homo sapiens, it can be deduced that variable regions are more helpful in differentiating the species at interspecific level rather than at intraspecific level. It was concluded that V3 was the least variable region in all the organisms, V2 and V7 were the longest expansion segments of D. melanogaster and there was continuous mutational bias towards G.C base pairing in H. sapiens. © 2014 Wiley Periodicals, Inc.

  14. Aquatic toxicity of glyphosate-based formulations: comparison between different organisms and the effects of environmental factors.

    Science.gov (United States)

    Tsui, Martin T K; Chu, L M

    2003-08-01

    Glyphosate-based herbicides (e.g. Roundup) are extensively used in the aquatic environment, but there is a paucity of data on the toxicity of the formulated products and the influences by environmental factors. In this study, the acute toxicity of technical-grade glyphosate acid, isopropylamine (IPA) salt of glyphosate, Roundup and its surfactant polyoxyethylene amine (POEA) to Microtox bacterium (Vibrio fischeri), microalgae (Selenastrum capricornutum and Skeletonema costatum), protozoa (Tetrahymena pyriformis and Euplotes vannus) and crustaceans (Ceriodaphnia dubia and Acartia tonsa) was examined and the relative toxicity contributions of POEA to Roundup were calculated. The effects of four environmental factors (temperature, pH, suspended sediment and algal food concentrations) on the acute toxicity of Roundup to C. dubia were also examined. Generally, the toxicity order of the chemicals was: POEA>Roundup>glyphosate acid>IPA salt of glyphosate, while the toxicity of glyphosate acid was mainly due to its high acidity. Microtox bacterium and protozoa had similar sensitivities towards Roundup toxicity (i.e. IC50 from 23.5 to 29.5 mg AE/l). In contrast, microalgae and crustaceans were 4-5 folds more sensitive to Roundup toxicity than bacteria and protozoa. Except photosynthetic microalgae, POEA accounted for more than 86% of Roundup toxicity and the toxicity contribution of POEA was shown to be species-dependent. Increase in pH (6-9) and increase of suspended sediment concentration (0-200 mg/l) significantly increased the toxicity of Roundup to C. dubia, but there were no significant effects due to temperature change and food addition.

  15. Generation and analysis of expressed sequence tags from the ciliate protozoan parasite Ichthyophthirius multifiliis

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    Arias Covadonga

    2007-06-01

    Full Text Available Abstract Background The ciliate protozoan Ichthyophthirius multifiliis (Ich is an important parasite of freshwater fish that causes 'white spot disease' leading to significant losses. A genomic resource for large-scale studies of this parasite has been lacking. To study gene expression involved in Ich pathogenesis and virulence, our goal was to generate expressed sequence tags (ESTs for the development of a powerful microarray platform for the analysis of global gene expression in this species. Here, we initiated a project to sequence and analyze over 10,000 ESTs. Results We sequenced 10,368 EST clones using a normalized cDNA library made from pooled samples of the trophont, tomont, and theront life-cycle stages, and generated 9,769 sequences (94.2% success rate. Post-sequencing processing led to 8,432 high quality sequences. Clustering analysis of these ESTs allowed identification of 4,706 unique sequences containing 976 contigs and 3,730 singletons. These unique sequences represent over two million base pairs (~10% of Plasmodium falciparum genome, a phylogenetically related protozoan. BLASTX searches produced 2,518 significant (E-value -5 hits and further Gene Ontology (GO analysis annotated 1,008 of these genes. The ESTs were analyzed comparatively against the genomes of the related protozoa Tetrahymena thermophila and P. falciparum, allowing putative identification of additional genes. All the EST sequences were deposited by dbEST in GenBank (GenBank: EG957858–EG966289. Gene discovery and annotations are presented and discussed. Conclusion This set of ESTs represents a significant proportion of the Ich transcriptome, and provides a material basis for the development of microarrays useful for gene expression studies concerning Ich development, pathogenesis, and virulence.

  16. Personal care product preservatives: risk assessment and mixture toxicities with an industrial wastewater.

    Science.gov (United States)

    Carbajo, Jose B; Perdigón-Melón, Jose A; Petre, Alice L; Rosal, Roberto; Letón, Pedro; García-Calvo, Eloy

    2015-04-01

    The aquatic toxicity of eight preservatives frequently used in personal care products (PCPs) (iodopropynyl butylcarbamate, bronopol, diazolidinyl urea, benzalkonium chloride, zinc pyrithione, propylparaben, triclosan and a mixture of methylchloroisothiazolinone and methylisothiazolinone) was assessed by means of two different approaches: a battery of bioassays composed of single species tests of bacteria (Vibrio fischeri and Pseudomonas putida) and protozoa (Tetrahymena thermophila), and a whole biological community resazurin-based assay using activated sludge. The tested preservatives showed considerable toxicity in the studied bioassays, but with a marked difference in potency. In fact, all biocides except propylparaben and diazolidinyl urea had EC50 values lower than 1 mg L(-1) in at least one assay. Risk quotients for zinc pyrithione, benzalkonium chloride, iodopropynyl butylcarbamate and triclosan as well as the mixture of the studied preservatives exceeded 1, indicating a potential risk for the process performance and efficiency of municipal sewage treatment plants (STPs). These four single biocides explained more than 95% of the preservative mixture risk in all bioassays. Each individual preservative was also tested in combination with an industrial wastewater (IWW) from a cosmetics manufacturing facility. The toxicity assessment was performed on binary mixtures (preservative + IWW) and carried out using the median-effect principle, which is a special case of the concept of Concentration Addition (CA). Almost 70% of all experiments resulted in EC50 values within a factor of 2 of the values predicted by the median-effect principle (CI values between 0.5 and 2). The rest of the mixtures whose toxicity was mispredicted by CA were assessed with the alternative concept of Independent Action (IA), which showed higher predictive power for the biological community assay. Therefore, the concept used to accurately predict the toxicity of mixtures of a preservative

  17. Cross-study analysis of genomic data defines the ciliate multigenic epiplasmin family: strategies for functional analysis in Paramecium tetraurelia.

    Science.gov (United States)

    Damaj, Raghida; Pomel, Sébastien; Bricheux, Geneviève; Coffe, Gérard; Viguès, Bernard; Ravet, Viviane; Bouchard, Philippe

    2009-06-03

    The sub-membranous skeleton of the ciliate Paramecium, the epiplasm, is composed of hundreds of epiplasmic scales centered on basal bodies, and presents a complex set of proteins, epiplasmins, which belong to a multigenic family. The repeated duplications observed in the P. tetraurelia genome present an interesting model of the organization and evolution of a multigenic family within a single cell. To study this multigenic family, we used phylogenetic, structural, and analytical transcriptional approaches. The phylogenetic method defines 5 groups of epiplasmins in the multigenic family. A refined analysis by Hydrophobic Cluster Analysis (HCA) identifies structural characteristics of 51 epiplasmins, defining five separate groups, and three classes. Depending on the sequential arrangement of their structural domains, the epiplasmins are defined as symmetric, asymmetric or atypical. The EST data aid in this classification, in the identification of putative regulating sequences such as TATA or CAAT boxes. When specific RNAi experiments were conducted using sequences from either symmetric or asymmetric classes, phenotypes were drastic. Local effects show either disrupted or ill-shaped epiplasmic scales. In either case, this results in aborted cell division. Using structural features, we show that 4 epiplasmins are also present in another ciliate, Tetrahymena thermophila. Their affiliation with the distinctive structural groups of Paramecium epiplasmins demonstrates an interspecific multigenic family. The epiplasmin multigenic family illustrates the history of genomic duplication in Paramecium. This study provides a framework which can guide functional analysis of epiplasmins, the major components of the membrane skeleton in ciliates. We show that this set of proteins handles an important developmental information in Paramecium since maintenance of epiplasm organization is crucial for cell morphogenesis.

  18. Cross-study analysis of genomic data defines the ciliate multigenic epiplasmin family: strategies for functional analysis in Paramecium tetraurelia

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    Ravet Viviane

    2009-06-01

    Full Text Available Abstract Background The sub-membranous skeleton of the ciliate Paramecium, the epiplasm, is composed of hundreds of epiplasmic scales centered on basal bodies, and presents a complex set of proteins, epiplasmins, which belong to a multigenic family. The repeated duplications observed in the P. tetraurelia genome present an interesting model of the organization and evolution of a multigenic family within a single cell. Results To study this multigenic family, we used phylogenetic, structural, and analytical transcriptional approaches. The phylogenetic method defines 5 groups of epiplasmins in the multigenic family. A refined analysis by Hydrophobic Cluster Analysis (HCA identifies structural characteristics of 51 epiplasmins, defining five separate groups, and three classes. Depending on the sequential arrangement of their structural domains, the epiplasmins are defined as symmetric, asymmetric or atypical. The EST data aid in this classification, in the identification of putative regulating sequences such as TATA or CAAT boxes. When specific RNAi experiments were conducted using sequences from either symmetric or asymmetric classes, phenotypes were drastic. Local effects show either disrupted or ill-shaped epiplasmic scales. In either case, this results in aborted cell division. Using structural features, we show that 4 epiplasmins are also present in another ciliate, Tetrahymena thermophila. Their affiliation with the distinctive structural groups of Paramecium epiplasmins demonstrates an interspecific multigenic family. Conclusion The epiplasmin multigenic family illustrates the history of genomic duplication in Paramecium. This study provides a framework which can guide functional analysis of epiplasmins, the major components of the membrane skeleton in ciliates. We show that this set of proteins handles an important developmental information in Paramecium since maintenance of epiplasm organization is crucial for cell morphogenesis.

  19. Signalling in ciliates: long- and short-range signals and molecular determinants for cellular dynamics.

    Science.gov (United States)

    Plattner, Helmut

    2017-02-01

    In ciliates, unicellular representatives of the bikont branch of evolution, inter- and intracellular signalling pathways have been analysed mainly in Paramecium tetraurelia, Paramecium multimicronucleatum and Tetrahymena thermophila and in part also in Euplotes raikovi. Electrophysiology of ciliary activity in Paramecium spp. is a most successful example. Established signalling mechanisms include plasmalemmal ion channels, recently established intracellular Ca(2+) -release channels, as well as signalling by cyclic nucleotides and Ca(2+) . Ca(2+) -binding proteins (calmodulin, centrin) and Ca(2+) -activated enzymes (kinases, phosphatases) are involved. Many organelles are endowed with specific molecules cooperating in signalling for intracellular transport and targeted delivery. Among them are recently specified soluble N-ethylmaleimide-sensitive factor attachment protein receptors (SNAREs), monomeric GTPases, H(+) -ATPase/pump, actin, etc. Little specification is available for some key signal transducers including mechanosensitive Ca(2+) -channels, exocyst complexes and Ca(2+) -sensor proteins for vesicle-vesicle/membrane interactions. The existence of heterotrimeric G-proteins and of G-protein-coupled receptors is still under considerable debate. Serine/threonine kinases dominate by far over tyrosine kinases (some predicted by phosphoproteomic analyses). Besides short-range signalling, long-range signalling also exists, e.g. as firmly installed microtubular transport rails within epigenetically determined patterns, thus facilitating targeted vesicle delivery. By envisaging widely different phenomena of signalling and subcellular dynamics, it will be shown (i) that important pathways of signalling and cellular dynamics are established already in ciliates, (ii) that some mechanisms diverge from higher eukaryotes and (iii) that considerable uncertainties still exist about some essential aspects of signalling. © 2015 Cambridge Philosophical Society.

  20. Enthalpy-Driven RNA Folding: Single-Molecule Thermodynamics of Tetraloop–Receptor Tertiary Interaction†

    Science.gov (United States)

    Fiore, Julie L.; Kraemer, Benedikt; Koberling, Felix; Edmann, Rainer; Nesbitt, David J.

    2010-01-01

    RNA folding thermodynamics are crucial for structure prediction, which requires characterization of both enthalpic and entropic contributions of tertiary motifs to conformational stability. We explore the temperature dependence of RNA folding due to the ubiquitous GAAA tetraloop–receptor docking interaction, exploiting immobilized and freely diffusing single-molecule fluorescence resonance energy transfer (smFRET) methods. The equilibrium constant for intramolecular docking is obtained as a function of temperature (T = 21–47 °C), from which a van’t Hoff analysis yields the enthalpy (ΔH°) and entropy (ΔS°) of docking. Tetraloop–receptor docking is significantly exothermic and entropically unfavorable in 1 mM MgCl2 and 100 mM NaCl, with excellent agreement between immobilized (ΔH° = −17.4 ± 1.6 kcal/mol, and ΔS° = −56.2 ± 5.4 cal mol−1 K−1) and freely diffusing (ΔH° = −17.2 ± 1.6 kcal/mol, and ΔS° = −55.9 ± 5.2 cal mol−1 K−1) species. Kinetic heterogeneity in the tetraloop–receptor construct is unaffected over the temperature range investigated, indicating a large energy barrier for interconversion between the actively docking and nondocking subpopulations. Formation of the tetraloop–receptor interaction can account for ~60% of the ΔH° and ΔS° of P4–P6 domain folding in the Tetrahymena ribozyme, suggesting that it may act as a thermodynamic clamp for the domain. Comparison of the isolated tetraloop–receptor and other tertiary folding thermodynamics supports a theme that enthalpy- versus entropy-driven folding is determined by the number of hydrogen bonding and base stacking interactions. PMID:19186984

  1. Evolutionary origins and functions of the carotenoid biosynthetic pathway in marine diatoms.

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    Sacha Coesel

    Full Text Available Carotenoids are produced by all photosynthetic organisms, where they play essential roles in light harvesting and photoprotection. The carotenoid biosynthetic pathway of diatoms is largely unstudied, but is of particular interest because these organisms have a very different evolutionary history with respect to the Plantae and are thought to be derived from an ancient secondary endosymbiosis between heterotrophic and autotrophic eukaryotes. Furthermore, diatoms have an additional xanthophyll-based cycle for dissipating excess light energy with respect to green algae and higher plants. To explore the origins and functions of the carotenoid pathway in diatoms we searched for genes encoding pathway components in the recently completed genome sequences of two marine diatoms. Consistent with the supplemental xanthophyll cycle in diatoms, we found more copies of the genes encoding violaxanthin de-epoxidase (VDE and zeaxanthin epoxidase (ZEP enzymes compared with other photosynthetic eukaryotes. However, the similarity of these enzymes with those of higher plants indicates that they had very probably diversified before the secondary endosymbiosis had occurred, implying that VDE and ZEP represent early eukaryotic innovations in the Plantae. Consequently, the diatom chromist lineage likely obtained all paralogues of ZEP and VDE genes during the process of secondary endosymbiosis by gene transfer from the nucleus of the algal endosymbiont to the host nucleus. Furthermore, the presence of a ZEP gene in Tetrahymena thermophila provides the first evidence for a secondary plastid gene encoded in a heterotrophic ciliate, providing support for the chromalveolate hypothesis. Protein domain structures and expression analyses in the pennate diatom Phaeodactylum tricornutum indicate diverse roles for the different ZEP and VDE isoforms and demonstrate that they are differentially regulated by light. These studies therefore reveal the ancient origins of several

  2. Cation-Anion Interactions within the Nucleic Acid Ion Atmosphere Revealed by Ion Counting.

    Science.gov (United States)

    Gebala, Magdalena; Giambaşu, George M; Lipfert, Jan; Bisaria, Namita; Bonilla, Steve; Li, Guangchao; York, Darrin M; Herschlag, Daniel

    2015-11-25

    The ion atmosphere is a critical structural, dynamic, and energetic component of nucleic acids that profoundly affects their interactions with proteins and ligands. Experimental methods that "count" the number of ions thermodynamically associated with the ion atmosphere allow dissection of energetic properties of the ion atmosphere, and thus provide direct comparison to theoretical results. Previous experiments have focused primarily on the cations that are attracted to nucleic acid polyanions, but have also showed that anions are excluded from the ion atmosphere. Herein, we have systematically explored the properties of anion exclusion, testing the zeroth-order model that anions of different identity are equally excluded due to electrostatic repulsion. Using a series of monovalent salts, we find, surprisingly, that the extent of anion exclusion and cation inclusion significantly depends on salt identity. The differences are prominent at higher concentrations and mirror trends in mean activity coefficients of the electrolyte solutions. Salts with lower activity coefficients exhibit greater accumulation of both cations and anions within the ion atmosphere, strongly suggesting that cation-anion correlation effects are present in the ion atmosphere and need to be accounted for to understand electrostatic interactions of nucleic acids. To test whether the effects of cation-anion correlations extend to nucleic acid kinetics and thermodynamics, we followed the folding of P4-P6, a domain of the Tetrahymena group I ribozyme, via single-molecule fluorescence resonance energy transfer in solutions with different salts. Solutions of identical concentration but lower activity gave slower and less favorable folding. Our results reveal hitherto unknown properties of the ion atmosphere and suggest possible roles of oriented ion pairs or anion-bridged cations in the ion atmosphere for electrolyte solutions of salts with reduced activity. Consideration of these new results leads to

  3. Cation–Anion Interactions within the Nucleic Acid Ion Atmosphere Revealed by Ion Counting

    Science.gov (United States)

    Gebala, Magdalena; Giambasu, George M.; Lipfert, Jan; Bisaria, Namita; Bonilla, Steve; Li, Guangchao; York, Darrin M.; Herschlag, Daniel

    2016-01-01

    The ion atmosphere is a critical structural, dynamic, and energetic component of nucleic acids that profoundly affects their interactions with proteins and ligands. Experimental methods that “count” the number of ions thermodynamically associated with the ion atmosphere allow dissection of energetic properties of the ion atmosphere, and thus provide direct comparison to theoretical results. Previous experiments have focused primarily on the cations that are attracted to nucleic acid polyanions, but have also showed that anions are excluded from the ion atmosphere. Herein, we have systematically explored the properties of anion exclusion, testing the zeroth-order model that anions of different identity are equally excluded due to electrostatic repulsion. Using a series of monovalent salts, we find, surprisingly, that the extent of anion exclusion and cation inclusion significantly depends on salt identity. The differences are prominent at higher concentrations and mirror trends in mean activity coefficients of the electrolyte solutions. Salts with lower activity coefficients exhibit greater accumulation of both cations and anions within the ion atmosphere, strongly suggesting that cation–anion correlation effects are present in the ion atmosphere and need to be accounted for to understand electrostatic interactions of nucleic acids. To test whether the effects of cation–anion correlations extend to nucleic acid kinetics and thermodynamics, we followed the folding of P4–P6, a domain of the Tetrahymena group I ribozyme, via single-molecule fluorescence resonance energy transfer in solutions with different salts. Solutions of identical concentration but lower activity gave slower and less favorable folding. Our results reveal hitherto unknown properties of the ion atmosphere and suggest possible roles of oriented ion pairs or anion-bridged cations in the ion atmosphere for electrolyte solutions of salts with reduced activity. Consideration of these new

  4. Interaction of pyrrolobenzodiazepine (PBD ligands with parallel intermolecular G-quadruplex complex using spectroscopy and ESI-MS.

    Directory of Open Access Journals (Sweden)

    Gajjela Raju

    Full Text Available Studies on ligand interaction with quadruplex DNA, and their role in stabilizing the complex at concentration prevailing under physiological condition, has attained high interest. Electrospray ionization mass spectrometry (ESI-MS and spectroscopic studies in solution were used to evaluate the interaction of PBD and TMPyP4 ligands, stoichiometry and selectivity to G-quadruplex DNA. Two synthetic ligands from PBD family, namely pyrene-linked pyrrolo[2,1-c][1,4]benzodiazepine hybrid (PBD1, mixed imine-amide pyrrolobenzodiazepine dimer (PBD2 and 5,10,15,20-tetrakis(N-methyl-4-pyridylporphyrin (TMPyP4 were studied. G-rich single-stranded oligonucleotide d(5'GGGGTTGGGG3' designated as d(T(2G(8, from the telomeric region of Tetrahymena Glaucoma, was considered for the interaction with ligands. ESI-MS and spectroscopic methods viz., circular dichroism (CD, UV-Visible, and fluorescence were employed to investigate the G-quadruplex structures formed by d(T(2G(8 sequence and its interaction with PBD and TMPyP4 ligands. From ESI-MS spectra, it is evident that the majority of quadruplexes exist as d(T(2G(8(2 and d(T(2G(8(4 forms possessing two to ten cations in the centre, thereby stabilizing the complex. CD band of PBD1 and PBD2 showed hypo and hyperchromicity, on interaction with quadruplex DNA, indicating unfolding and stabilization of quadruplex DNA complex, respectively. UV-Visible and fluorescence experiments suggest that PBD1 bind externally where as PBD2 intercalate moderately and bind externally to G-quadruplex DNA. Further, melting experiments using SYBR Green indicate that PBD1 unfolds and PBD2 stabilizes the G-quadruplex complex. ITC experiments using d(T(2G(8 quadruplex with PBD ligands reveal that PBD1 and PBD2 prefer external/loop binding and external/intercalative binding to quadruplex DNA, respectively. From experimental results it is clear that the interaction of PBD2 and TMPyP4 impart higher stability to the quadruplex complex.

  5. [Mating types in the ciliate Dileptus anser. Inheritance and genetic determination].

    Science.gov (United States)

    Iudin, A L; Uspenskaia, Z I

    2006-01-01

    Hybridological analysis of mating types (MTs) has been first made for the lower ciliate Dileptus anser. Clones of an initially unknown genotype belonging to three MTs (MT I, MT II and MT III), characteristic of D. anser, were isolated from natural reservoirs and further used for crosses. In one group crosses, synclonal inheritance and typical Mendelian behaviour of the character were observed over sexual generations of ciliates. The results suggest that MTs in D. anser may be directly controlled by a single mat locus with three alleles showing peck-order dominance (mat1 > mat2 > mat3). In other words, cells with mat1/mat1, mat1/mat2 and mat1/mat3 genotypes belong to MT I, those with mat2/mat2 and mat2/mat3, and the mat3/mat3 belong to MT II and MT III, respectively. Sexually mature exconjugant clones stably retain their MTs corresponding to their genotypes on vegetative reproduction. The progeny of other group crosses showed various deviations from typical Mendelian behaviour of the character. In some cases, standard Mendelian ratios were more or less violated. Most typical was instability of differentiation for MT in maturing exconjugant clones. Shortly after their maturation, the majority of clones change their MT, rather frequently more than once, although the finally established MT is stably inherited afterwards, during vegetative reproduction. When unstable, exconjugant clones can successively express two or even three MTs characteristic of this species, including MTs that should not have been expected on the basis of parental genotypes available in a given cross. It looks likely that the mat locus in D. anser is complex and multipotential; it is inherited as a whole providing for expression of any MT characteristic of the species (in this respect bearing similarity with Tetrahymena thermophila). Other mechanisms, epigenetic in particular (Nanney, 1958), determine the final expression of one of the three MT potentialities by a given exconjugant clone. Stable

  6. The mitochondrial genome sequence of the ciliate Paramecium caudatum reveals a shift in nucleotide composition and codon usage within the genus Paramecium

    Directory of Open Access Journals (Sweden)

    Berendonk Thomas U

    2011-05-01

    Full Text Available Abstract Background Despite the fact that the organization of the ciliate mitochondrial genome is exceptional, only few ciliate mitochondrial genomes have been sequenced until today. All ciliate mitochondrial genomes are linear. They are 40 kb to 47 kb long and contain some 50 tightly packed genes without introns. Earlier studies documented that the mitochondrial guanine + cytosine contents are very different between Paramecium tetraurelia and all studied Tetrahymena species. This raises the question of whether the high mitochondrial G+C content observed in P. tetraurelia is a characteristic property of Paramecium mtDNA, or whether it is an exception of the ciliate mitochondrial genomes known so far. To test this question, we determined the mitochondrial genome sequence of Paramecium caudatum and compared the gene content and sequence properties to the closely related P. tetraurelia. Results The guanine + cytosine content of the P. caudatum mitochondrial genome was significantly lower than that of P. tetraurelia (22.4% vs. 41.2%. This difference in the mitochondrial nucleotide composition was accompanied by significantly different codon usage patterns in both species, i.e. within P. caudatum clearly A/T ending codons dominated, whereas for P. tetraurelia the synonymous codons were more balanced with a higher number of G/C ending codons. Further analyses indicated that the nucleotide composition of most members of the genus Paramecium resembles that of P. caudatum and that the shift observed in P. tetraurelia is restricted to the P. aurelia species complex. Conclusions Surprisingly, the codon usage bias in the P. caudatum mitochondrial genome, exemplified by the effective number of codons, is more similar to the distantly related T. pyriformis and other single-celled eukaryotes such as Chlamydomonas, than to the closely related P. tetraurelia. These differences in base composition and codon usage bias were, however, not reflected in the amino

  7. A new family of giardial cysteine-rich non-VSP protein genes and a novel cyst protein.

    Directory of Open Access Journals (Sweden)

    Barbara J Davids

    2006-12-01

    Full Text Available Since the Giardia lamblia cyst wall is necessary for survival in the environment and host infection, we tested the hypothesis that it contains proteins other than the three known cyst wall proteins. Serial analysis of gene expression during growth and encystation revealed a gene, "HCNCp" (High Cysteine Non-variant Cyst protein, that was upregulated late in encystation, and that resembled the classic Giardia variable surface proteins (VSPs that cover the trophozoite plasmalemma. HCNCp is 13.9% cysteine, with many "CxxC" tetrapeptide motifs and a transmembrane sequence near the C-terminus. However, HCNCp has multiple "CxC" motifs rarely found in VSPs, and does not localize to the trophozoite plasmalemma. Moreover, the HCNCp C-terminus differed from the canonical VSP signature. Full-length epitope-tagged HCNCp expressed under its own promoter was upregulated during encystation with highest expression in cysts, including 42 and 21 kDa C-terminal fragments. Tagged HCNCp targeted to the nuclear envelope in trophozoites, and co-localized with cyst proteins to encystation-specific secretory vesicles during encystation. HCNCp defined a novel trafficking pathway as it localized to the wall and body of cysts, while the cyst proteins were exclusively in the wall. Unlike VSPs, HCNCp is expressed in at least five giardial strains and four WB subclones expressing different VSPs. Bioinformatics identified 60 additional large high cysteine membrane proteins (HCMp containing > or = 20 CxxC/CxC's lacking the VSP-specific C-terminal CRGKA. HCMp were absent or rare in other model or parasite genomes, except for Tetrahymena thermophila with 30. MEME analysis classified the 61 gHCMp genes into nine groups with similar internal motifs. Our data suggest that HCNCp is a novel invariant cyst protein belonging to a new HCMp family that is abundant in the Giardia genome. HCNCp and the other HCMp provide a rich source for developing parasite-specific diagnostic reagents

  8. Transcriptome analysis of the Cryptocaryon irritans tomont stage identifies potential genes for the detection and control of cryptocaryonosis

    Directory of Open Access Journals (Sweden)

    Wan Kiew-Lian

    2010-01-01

    Full Text Available Abstract Background Cryptocaryon irritans is a parasitic ciliate that causes cryptocaryonosis (white spot disease in marine fish. Diagnosis of cryptocaryonosis often depends on the appearance of white spots on the surface of the fish, which are usually visible only during later stages of the disease. Identifying suitable biomarkers of this parasite would aid the development of diagnostic tools and control strategies for C. irritans. The C. irritans genome is virtually unexplored; therefore, we generated and analyzed expressed sequence tags (ESTs of the parasite to identify genes that encode for surface proteins, excretory/secretory proteins and repeat-containing proteins. Results ESTs were generated from a cDNA library of C. irritans tomonts isolated from infected Asian sea bass, Lates calcarifer. Clustering of the 5356 ESTs produced 2659 unique transcripts (UTs containing 1989 singletons and 670 consensi. BLAST analysis showed that 74% of the UTs had significant similarity (E-value -5 to sequences that are currently available in the GenBank database, with more than 15% of the significant hits showing unknown function. Forty percent of the UTs had significant similarity to ciliates from the genera Tetrahymena and Paramecium. Comparative gene family analysis with related taxa showed that many protein families are conserved among the protozoans. Based on gene ontology annotation, functional groups were successfully assigned to 790 UTs. Genes encoding excretory/secretory proteins and membrane and membrane-associated proteins were identified because these proteins often function as antigens and are good antibody targets. A total of 481 UTs were classified as encoding membrane proteins, 54 were classified as encoding for membrane-bound proteins, and 155 were found to contain excretory/secretory protein-coding sequences. Amino acid repeat-containing proteins and GPI-anchored proteins were also identified as potential candidates for the development of

  9. Identification of hopanoid, sterol, and tetrahymanol production in the aerobic methanotroph Methylomicrobium alcaliphilum 20Z

    Science.gov (United States)

    Welander, P. V.; Summons, R. E.

    2013-12-01

    observed in freshwater and marine ciliates (such as Tetrahymena thermophila) and two bacteria unrelated to aerobic methanotrophs, Rhodopseudomonas and Bradyrhizobium. Utilizing comparative genomics we identified the oxidosqualene cyclase gene required for sterol biosynthesis as well as two copies of the squalene hopene cyclase gene necessary for hopanoid biosynthesis in the M. alcaliphilum genome. To determine if one or both copies of the squalene hopene cyclase gene were necessary for aminohopanoid or tetrahymanol production, shc gene deletions were constructed and the subsequent mutants were analyzed for impaired hopanoid production. The occurrence of sterols, hopanoids and gammacerane lipids in one bacterium not only provides a unique system in which to study the biosynthesis and function of each lipid class but also to investigate any potential functional and evolutionary relationship these three lipid classes may share. In turn, these studies provide information necessary to properly interpret the occurrence of these molecules in the rock record.

  10. Combined effects of {gamma}-rays and acidification on an experimental model ecosystem

    Energy Technology Data Exchange (ETDEWEB)

    Fuma, Shoichi; Ishii, Nobuyoshi; Takeda, Hiroshi [National Inst. of Radiological Sciences, Chiba (Japan); Kawabata, Zen' ichiro [Kyoto Univ. (Japan). Center for Ecological Research; Ichimasa, Yusuke [Ibaraki Univ., Mito (Japan). Faculty of Science

    2002-05-01

    It is necessary to evaluate combined effects of ionizing radiation and other toxic agents on ecosystems, because ecosystems are exposed to these various factors. The authors studied combined effects of {gamma}-rays and acidification on an experimental model ecosystem (microcosm) mimicking aquatic microbial communities. Microcosms, consisted of flagellate algae Euglena gracilis Z as a producer, ciliate protozoa Tetrahymena thermophila B as a consumer and bacteria Escherichia coli DH5{alpha} as a decomposer, were loaded by the following treatments: Irradiation with 100 Gy {sup 60}Co {gamma}-rays; Acidification of culture medium to pH4.0 with the mixture of 0.1 N HNO{sub 3} and 0.1 N H{sub 2}SO{sub 4} (1:1, v/v), which mimicked acid rain; and Irradiation with 100 Gy {gamma}-rays followed by the acidification of the culture medium (pH 4.0). The {gamma}-irradiation induced a temporary decrease in cell densities of E. coli, but did not affect cell densities of the other species. The concentrations of chlorophyll a and ATP in the microcosm were not affected by the {gamma}-irradiation, and chlorophyll a concentrations in a Eu. gracilis cell were not affected, either. The acidification significantly decreased cell densities of T. thermophila, slightly decreased cell densities of E. coli, and slightly increased cell densities of Eu. gracilis. The concentrations of chlorophyll a and ATP in the microcosm were increased by the acidification, although chlorophyll a concentrations in a Eu. gracilis cell were decreased. The combined exposure to {gamma}-rays and acids temporarily decreased cell densities of E. coli, significantly decreased cell densities of T. thermophila, and slightly increased cell densities of Eu. gracilis. The concentrations of chlorophyll a and ATP in the microcosm were increased by the combined exposure, although chlorophyll a concentrations in a Eu. gracilis cell were decreased. The authors therefore conclude that combined exposure to {gamma}-rays and acids

  11. [Transgenic bioinsecticides inimical to parasites, but imical to environment].

    Science.gov (United States)

    Kucińska, Jolanta; Lonc, Elzbieta; Rydzanicz, Katarzyna

    2003-01-01

    Identification of Bacillus thuringiensis (Bt) parasporal crystalline inclusions composed of Cry proteins (=delta-endotoxins) resulted in introduction of microbial pesticides for biological control of some parasites. Delta-endotoxins are encoded by cry genes and are active against pest and nuisance insects (mostly mosquitoes and black flies--vectors of still important infectious diseases). The recent significant progress in DNA recombination technique may overcome limitations (a short residual persistence and a narrow spectrum of activity) associated with application of Bt conventional products. An introduction of cry genes from mosquitocidal subspecies B. th. israelensis (Bti) to the aquatic microorganisms inhabiting the same water bodies as mosquito and fly larvae (Diptera), has considerably improved the toxin delivery system to target insects. However, in the first experiments, in which Bti genes were cloned in cyanobacteria (Agmenellum quadruplicatum, Synechocystis PCC6803), a low gene expression was observed. Thus, it was necessary to integrate cry genes with strong promoters or to increase the number of vector-introduced copies. To overcome the obstacles of low gene expression and regulatory restriction for recombinant organisms, Bti spore/crystal formulations were encapsulated in the aquatic protozoan, Tetrahymena pyriformis. Large numbers of crystals (180 to 240/cell) were accumulated in its food vacuoles. This system resulted also in an increase in toxin persistence from 24 to 71 h. Cloning Bti genes in B. sphaericus (which also produces mosquitocidal proteins) was another way of an increasing Bt crystal residual activity. In this case, the crystals were additionally protected by B. sphaericus exosporium. These transgenic bacteria produced large amounts of delta-endotoxins that remained under water surface longer than the wild B. sphaericus strains. Moreover, they had a broader spectrum of insecticidal activity, because B. sphaericus is toxic mostly to

  12. Coexistence of silver and titanium dioxide nanoparticles: enhancing or reducing environmental risks?

    Science.gov (United States)

    Zou, Xiaoyan; Shi, Junpeng; Zhang, Hongwu

    2014-09-01

    Due to their bactericidal and photocatalytic characteristics, silver nanoparticles (Ag NPs) and titanium dioxide nanoparticles (TiO2 NPs) are widely used in the fields of environment and physiology. Once these untreated nanoparticles are released into an aquatic environment and encounter one another, there is more uncertainty about their fate and ecotoxicological risks compared with the single nanoparticles. To expand our knowledge of the health and environmental impacts of nanoparticles, we investigated the possible risk of the co-existence of TiO2 NPs and Ag NPs in an aquatic environment using ciliated protozoa (Tetrahymena pyriformis) as an aquatic animal model. In this study, silver ion (Ag(+)) release and physicochemical properties, as well as their effect on oxidative stress biomarkers, were monitored. Continuous illumination (12,000 lx) led to the 20.0% decrease in Ag(+) release in comparison with dark conditions, while TiO2 NPs and continuous illumination resulted in decreasing the Ag(+) concentration to 64.3% in contrast with Ag NPs-only suspensions. Toxicity tests indicated that different illumination modes exerted distinct effects of TiO2 NPs on the toxicity of Ag NPs: no effects, antagonism and synergism in dark, natural light and continuous light, respectively. In the presence of 1.5mg/L (18.8 μM) TiO2 NPs, the toxicity of 1.5 mg/L (13.9 μM) Ag NPs was reduced by 28.7% and increased by 6.93% in natural light and 12,000 lx of continuous light, respectively. After culturing in 12,000 lx continuous light for 24h, SOD activity of the light control surged to 1.96 times compared to the dark control (P<0.001). TiO2 NPs induced a reduction of CAT activity by an average of (36.1±1.7) % in the light. In the natural light reductions in the toxicity of Ag, NPs decrease Ag(+) concentrations via adsorption of Ag(+) onto TiO2 NPs surfaces. The enhancement of Ag NPs toxicity can contribute to the formation of activated TiO2-Ag NPs complexes in continuous light. The

  13. Targeting of highly conserved Dengue virus sequences with anti-Dengue virus trans-splicing group I introns

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    Fraser Tresa S

    2010-11-01

    Full Text Available Abstract Background Dengue viruses (DENV are one of the most important viral diseases in the world with approximately 100 million infections and 200,000 deaths each year. The current lack of an approved tetravalent vaccine and ineffective insecticide control measures warrant a search for alternatives to effectively combat DENV. The trans-splicing variant of the Tetrahymena thermophila group I intron catalytic RNA, or ribozyme, is a powerful tool for post-transcriptional RNA modification. The nature of the ribozyme and the predictability with which it can be directed makes it a powerful tool for modifying RNA in nearly any cell type without the need for genome-altering gene therapy techniques or dependence on native cofactors. Results Several anti-DENV Group I trans-splicing introns (αDENV-GrpIs were designed and tested for their ability to target DENV-2 NGC genomes in situ. We have successfully targeted two different uracil bases on the positive sense genomic strand within the highly conserved 5'-3' cyclization sequence (CS region common to all serotypes of DENV with our αDENV-GrpIs. Our ribozymes have demonstrated ability to specifically trans-splice a new RNA sequence downstream of the targeted site in vitro and in transfected insect cells as analyzed by firefly luciferase and RT-PCR assays. The effectiveness of these αDENV-GrpIs to target infecting DENV genomes is also validated in transfected or transformed Aedes mosquito cell lines upon infection with unattenuated DENV-2 NGC. Conclusions Analysis shows that our αDENV-GrpIs have the ability to effectively trans-splice the DENV genome in situ. Notably, these results show that the αDENV-GrpI 9v1, designed to be active against all forms of Dengue virus, effectively targeted the DENV-2 NGC genome in a sequence specific manner. These novel αDENV-GrpI introns provide a striking alternative to other RNA based approaches for the transgenic suppression of DENV in transformed mosquito cells and

  14. Convergent evolution of heat-inducibility during subfunctionalization of the Hsp70 gene family.

    Science.gov (United States)

    Krenek, Sascha; Schlegel, Martin; Berendonk, Thomas U

    2013-02-21

    hsp70s unveiled a corresponding expression pattern, which supports a functionally conserved evolution of the Hsp70 gene family in Paramecium. Our analyses suggest an independent evolution of the heat-inducible cytosol-type hsp70s in Paramecium and in its close relative Tetrahymena, as well as within higher eukaryotes. This result indicates convergent evolution during hsp70 subfunctionalization and implies that heat-inducibility evolved several times during the course of eukaryotic evolution.

  15. The mitochondrial genome sequence of the ciliate Paramecium caudatum reveals a shift in nucleotide composition and codon usage within the genus Paramecium.

    Science.gov (United States)

    Barth, Dana; Berendonk, Thomas U

    2011-05-31

    Despite the fact that the organization of the ciliate mitochondrial genome is exceptional, only few ciliate mitochondrial genomes have been sequenced until today. All ciliate mitochondrial genomes are linear. They are 40 kb to 47 kb long and contain some 50 tightly packed genes without introns. Earlier studies documented that the mitochondrial guanine + cytosine contents are very different between Paramecium tetraurelia and all studied Tetrahymena species. This raises the question of whether the high mitochondrial G+C content observed in P. tetraurelia is a characteristic property of Paramecium mtDNA, or whether it is an exception of the ciliate mitochondrial genomes known so far. To test this question, we determined the mitochondrial genome sequence of Paramecium caudatum and compared the gene content and sequence properties to the closely related P. tetraurelia. The guanine + cytosine content of the P. caudatum mitochondrial genome was significantly lower than that of P. tetraurelia (22.4% vs. 41.2%). This difference in the mitochondrial nucleotide composition was accompanied by significantly different codon usage patterns in both species, i.e. within P. caudatum clearly A/T ending codons dominated, whereas for P. tetraurelia the synonymous codons were more balanced with a higher number of G/C ending codons. Further analyses indicated that the nucleotide composition of most members of the genus Paramecium resembles that of P. caudatum and that the shift observed in P. tetraurelia is restricted to the P. aurelia species complex. Surprisingly, the codon usage bias in the P. caudatum mitochondrial genome, exemplified by the effective number of codons, is more similar to the distantly related T. pyriformis and other single-celled eukaryotes such as Chlamydomonas, than to the closely related P. tetraurelia. These differences in base composition and codon usage bias were, however, not reflected in the amino acid composition. Most probably, the observed picture is best

  16. Ingredients for protist coexistence: competition, endosymbiosis and a pinch of biochemical interactions.

    Science.gov (United States)

    Müller, Johann P; Hauzy, Céline; Hulot, Florence D

    2012-01-01

    1. The interaction between mutualism, facilitation or interference and exploitation competition is of major interest as it may govern species coexistence. However, the interplay of these mechanisms has received little attention. This issue dates back to Gause, who experimentally explored competition using protists as a model [Gause, G.F. (1935) Vérifications expérimentales de la théorie mathématique de la lutte pour la vie. Actualités Scientifiques et Industrielles, 277]. He showed the coexistence of Paramecium caudatum with a potentially allelopathic species, Paramecium bursaria. 2. Paramecium bursaria hosts the green algae Chlorella vulgaris. Therefore, P. bursaria may benefit from carbohydrates synthesised by the algae. Studying endosymbiosis with P. bursaria is possible as it can be freed of its endosymbiont. In addition, C. vulgaris is known to produce allelochemicals, and P. bursaria may benefit also from allelopathic compounds. 3. We designed an experiment to separate the effects of resource exploitation, endosymbiosis and allelopathy and to assess their relative importance for the coexistence of P. bursaria with a competitor that exploits the same resource, bacteria. The experiment was repeated with two competitors, Colpidium striatum or Tetrahymena pyriformis. 4. Results show that the presence of the endosymbiont enables the coexistence of competitors, while its loss leads to competitive exclusion. These results are in agreement with predictions based on resource equilibrium density of monocultures (R*) supporting the idea that P. bursaria's endosymbiont is a resource provider for its host. When P. bursaria and T. pyriformis coexist, the density of the latter shows large variation that match the effects of culture medium of P. bursaria. Our experiment suggests these effects are because of biochemicals produced in P. bursaria culture. 5. Our results expose the hidden diversity of mechanisms that underlie competitive interactions. They thus support

  17. Modification of polychlorinated phenols and evaluation of their toxicity, biodegradation and bioconcentration using three-dimensional quantitative structure-activity relationship models.

    Science.gov (United States)

    Tong, Lidan; Guo, Lixin; Lv, Xiaojun; Li, Yu

    2017-01-01

    molecules as a pesticide was verified using a 3D-QSAR model for polychlorinated phenol toxicity against Tetrahymena pyriformis. Four of these compounds, with -Br, -I, -OH and -NH2 groups in place of chlorine at the 3-position on PCP, were all at least as effective as PCP against T. Pyriformis. The first-order rate constants (Kb) of these four compounds were predicted using a 3D-QSAR model for polychlorinated phenol degradation, which showed they were more biodegradable than PCP. Furthermore, a 3D-QSAR model for polychlorinated phenols bioconcentration in fish (containing Poecilia reticulata, Oncorhynchus mykiss, Pimephales promelas and Oryzias latipes) showed that there was no significant difference between the bioconcentration factors of the four new compounds and that of PCP. The results obtained are hoped to provide a new route for lowering the POPs characteristics of those polychlorinated phenol homologues and derivatives in use. Copyright © 2016 Elsevier Inc. All rights reserved.