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Tetrahymena

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https://www.readbyqxmd.com/read/28641232/on-the-aquatic-toxicity-of-substituted-phenols-to-chlorella-vulgaris-qstr-with-an-extended-novel-data-set-and-interspecies-models
#1
Gulcin Tugcu, M Doğa Ertürk, Melek Türker Saçan
This study provides for the first time the 96-h toxicity of 16 nitro- and methyl- substituted phenols to Chlorella vulgaris. Enabling the circulation of new ecotoxicity data has expanded the previously reported toxicity data set of 30 phenols to C. vulgaris by our laboratory. In this respect, high quality, single source algal toxicity data, generated in the same laboratory according to a REACH (Registration, Evaluation, Authorization and Restriction of CHemicals) compatible endpoint, provided a sound basis to explore quantitative structure-toxicity relationship (QSTR), which can be used for regulatory purposes...
June 15, 2017: Journal of Hazardous Materials
https://www.readbyqxmd.com/read/28621664/post-meiotic-dna-double-strand-breaks-occur-in-tetrahymena-and-require-topoisomerase-ii-and-spo11
#2
Takahiko Akematsu, Yasuhiro Fukuda, Jyoti Garg, Jeffrey S Fillingham, Ronald E Pearlman, Josef Loidl
Based on observations of markers for DNA lesions, such as phosphorylated histone H2AX (γH2AX) and open DNA ends, it has been suggested that post-meiotic DNA double-strand breaks (PM-DSBs) enable chromatin remodeling during animal spermiogenesis. However, the existence of PM-DSBs is unconfirmed, and the mechanism responsible for their formation is unclear. Here, we report the first direct observation of programmed PM-DSBs via the electrophoretic separation of DSB-generated DNA fragments in the ciliate Tetrahymena thermophila...
June 16, 2017: ELife
https://www.readbyqxmd.com/read/28595932/characterization-of-ciliate-diversity-in-bromeliad-tank-waters-from-the-brazilian-atlantic-forest
#3
Taiz L L Simão, Adriana Giongo Borges, Kelsey A Gano, Austin G Davis-Richardson, Christopher T Brown, Jennie R Fagen, Eric W Triplett, Raquel Dias, Claudio A Mondin, Renata M da Silva, Eduardo Eizirik, Laura R P Utz
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...
May 17, 2017: European Journal of Protistology
https://www.readbyqxmd.com/read/28594294/ceo2-nanoparticles-alter-the-outcome-of-species-interactions
#4
Cheng Peng, Ying Chen, Zhichao Pu, Qing Zhao, Xin Tong, Yongsheng Chen, Lin Jiang
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...
June 8, 2017: Nanotoxicology
https://www.readbyqxmd.com/read/28562242/ift-trains-in-different-stages-of-assembly-queue-at-the-ciliary-base-for-consecutive-release-into-the-cilium
#5
Jenna L Wingfield, Ilaria Mengoni, Heather Bomberger, Yu-Yang Jiang, Jonathon D Walsh, Jason M Brown, Tyler Picariello, Deborah A Cochran, Bing Zhu, Junmin Pan, Jonathan Eggenschwiler, Jacek Gaertig, George B Witman, Peter Kner, Karl Lechtreck
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...
May 31, 2017: ELife
https://www.readbyqxmd.com/read/28559213/phylogenomic-analysis-of-integral-diiron-membrane-histidine-motif-containing-enzymes-in-ciliates-provides-insights-into-their-function-and-evolutionary-relationships
#6
Nicolas G Cid, María L Sanchez Granel, María G Montes, María E Elguero, Clara B Nudel, Alejandro D Nusblat
The Integral Membrane Histidine Motif-containing Enzymes (IMHME) are a class of binuclear non-heme iron proteins widely distributed among prokaryotes and eukaryotes. They are characterized by a conserved tripartite motif consisting of eight to ten histidine residues. Their known function is the activation of the dioxygen moiety to serve as efficient catalysts for reactions of hydroxylation, desaturation or reduction. To date most studies on IMHME were carried out in metazoan, phototrophic or parasitic organisms, whereas genome-wide analysis in heterotrophic free living protozoa, such as the Ciliophora phylum, has not been undertaken...
May 27, 2017: Molecular Phylogenetics and Evolution
https://www.readbyqxmd.com/read/28556398/heterodimerization-of-group-i-ribozymes-enabling-exon-recombination-through-a-pair-of-cooperative-trans-splicing-reactions
#7
Takahiro Tanaka, Yusuke Hirata, Yuto Tominaga, Hiroyuki Furuta, Shigeyoshi Matsumura, Yoshiya Ikawa
Group I self-splicing (GI) ribozymes are attractive tools for biotechnology and synthetic biology. Several trans-splicing and related reactions have been developed based on GI ribozymes to recombine their target mRNA sequences. By combining trans-splicing systems with rational modular engineering of GI ribozymes, more complex editing of target RNA sequences could be achieved. In this study, we developed a cooperative trans-splicing system based on dimeric GI ribozymes derived from the Tetrahymena group I intron ribozyme through rational modular engineering...
May 29, 2017: Chembiochem: a European Journal of Chemical Biology
https://www.readbyqxmd.com/read/28509379/microbial-eukaryotes-that-lack-sterols
#8
Kiyotaka Takishita, Yoshito Chikaraishi, Goro Tanifuji, Naohiko Ohkouchi, Tetsuo Hashimoto, Katsunori Fujikura, Andrew J Roger
It is widely held that sterols are key cyclic triterpenoid lipids in eukaryotic cell membranes and are synthesized through oxygen-dependent multienzyme pathways. However, there are known exceptions-ciliated protozoans, such as Tetrahymena, along with diverse low-oxygen-adapted eukaryotes produce, instead of sterols, the cyclic triterpenoid lipid tetrahymanol that does not require molecular oxygen for its biosynthesis. Here, we report that a number of anaerobic microbial eukaryotes (protists) utilize neither sterols nor tetrahymanol in their membranes...
May 16, 2017: Journal of Eukaryotic Microbiology
https://www.readbyqxmd.com/read/28467816/prediction-of-the-aquatic-toxicity-of-aromatic-compounds-to-tetrahymena-pyriformis-through-support-vector-regression
#9
Qiang Su, Wencong Lu, Dongshu Du, Fuxue Chen, Bing Niu, Kuo-Chen Chou
Toxicity evaluation is an extremely important process during drug development. It is usually initiated by experiments on animals, which is time-consuming and costly. To speed up such a process, a quantitative structure-activity relationship (QSAR) study was performed to develop a computational model for correlating the structures of 581 aromatic compounds with their aquatic toxicity to tetrahymena pyriformis. A set of 68 molecular descriptors derived solely from the structures of the aromatic compounds were calculated based on Gaussian 03, HyperChem 7...
April 13, 2017: Oncotarget
https://www.readbyqxmd.com/read/28413159/the-hippo-pathway-maintains-the-equatorial-division-plane-in-the-ciliate-tetrahymena
#10
Yu-Yang Jiang, Wolfgang Maier, Ralf Baumeister, Gregory Minevich, Ewa Joachimiak, Zheng Ruan, Natarajan Kannan, Diamond Clarke, Joseph Frankel, Jacek Gaertig
The mechanisms that govern pattern formation within the cell are poorly understood. Ciliates carry on their surface an elaborate pattern of cortical organelles that are arranged along the anteroposterior and circumferential axes by largely unknown mechanisms. Ciliates divide by tandem duplication: the cortex of the pre-division cell is remodeled into two similarly-sized and complete daughters. In the conditional cdaI-1 mutant of Tetrahymena thermophila, the division plane migrates from its initially correct equatorial position toward the cell's anterior, resulting in unequal cell division, and defects in nuclear divisions and cytokinesis...
April 16, 2017: Genetics
https://www.readbyqxmd.com/read/28402567/nonsense-mediated-mrna-decay-in-tetrahymena-is-ejc-independent-and-requires-a-protozoa-specific-nuclease
#11
Miao Tian, Wentao Yang, Jing Zhang, Huai Dang, Xingyi Lu, Chengjie Fu, Wei Miao
Nonsense-mediated mRNA decay (NMD) is essential for removing premature termination codon-containing transcripts from cells. Studying the NMD pathway in model organisms can help to elucidate the NMD mechanism in humans and improve our understanding of how this biologically important process has evolved. Ciliates are among the earliest branching eukaryotes; their NMD mechanism is poorly understood and may be primordial. We demonstrate that highly conserved Upf proteins (Upf1a, Upf2 and Upf3) are involved in the NMD pathway of the ciliate, Tetrahymena thermophila...
April 11, 2017: Nucleic Acids Research
https://www.readbyqxmd.com/read/28398483/function-of-nuclear-membrane-proteins-in-shaping-the-nuclear-envelope-integrity-during-closed-mitosis
#12
Hui-Ju Yang, Masaaki Iwamoto, Yasushi Hiraoka, Tokuko Haraguchi
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...
June 1, 2017: Journal of Biochemistry
https://www.readbyqxmd.com/read/28386019/compositionally-distinct-nuclear-pore-complexes-of-functionally-distinct-dimorphic-nuclei-in-the-ciliate-tetrahymena
#13
Masaaki Iwamoto, Hiroko Osakada, Chie Mori, Yasuhiro Fukuda, Koji Nagao, Chikashi Obuse, Yasushi Hiraoka, Tokuko Haraguchi
The nuclear pore complex (NPC), a gateway for nucleocytoplasmic trafficking, is composed of ∼30 different proteins called nucleoporins. It remains unknown whether the NPCs within a species are homogeneous or vary depending on the cell type or physiological condition. Here, we present evidence for compositionally distinct NPCs that form within a single cell in a binucleated ciliate. In Tetrahymena thermophila, each cell contains both a transcriptionally active macronucleus (MAC) and a germline micronucleus (MIC)...
May 15, 2017: Journal of Cell Science
https://www.readbyqxmd.com/read/28381425/an-endosomal-syntaxin-and-the-ap-3-complex-are-required-for-formation-and-maturation-of-candidate-lysosome-related-secretory-organelles-mucocysts-in-tetrahymena-thermophila
#14
Harsimran Kaur, Daniela Sparvoli, Hiroko Osakada, Masaaki Iwamoto, Tokuko Haraguchi, Aaron P Turkewitz
The ciliate Tetrahymena thermophila synthesizes large secretory vesicles called mucocysts. Mucocyst biosynthesis shares features with dense core granules (DCGs) in animal cells, including proteolytic processing of cargo proteins during maturation. However, other molecular features have suggested relatedness to lysosome-related organelles (LROs). LROs, which include diverse organelles in animals, are formed via convergence of secretory and endocytic trafficking. Here we analyzed Tetrahymena syntaxin 7-like 1 (Stx7l1p), a Qa-SNARE whose homologues in other lineages are linked with vacuoles/LROs...
June 1, 2017: Molecular Biology of the Cell
https://www.readbyqxmd.com/read/28335309/separation-of-bacteria-protozoa-and-carbon-nanotubes-by-density-gradient-centrifugation
#15
Monika Mortimer, Elijah J Petersen, Bruce A Buchholz, Patricia A Holden
Sustainable production and use of carbon nanotube (CNT)-enabled materials require efficient assessment of CNT environmental hazards, including the potential for CNT bioaccumulation and biomagnification in environmental receptors. Microbes, as abundant organisms responsible for nutrient cycling in soil and water, are important ecological receptors for studying the effects of CNTs. Quantification of CNT association with microbial cells requires efficient separation of CNT-associated cells from individually dispersed CNTs and CNT agglomerates...
October 12, 2016: Nanomaterials
https://www.readbyqxmd.com/read/28334205/tetrahymena-phagocytic-vesicles-as-ecological-micro-niches-of-phage-transfer
#16
Iqbal Aijaz, Gerald B Koudelka
The microbial communities in natural environments such as soil, pond water, or animal rumens are composed of a diverse mixture of bacteria and protozoa including ciliates or flagellates. In such microbiomes, a major source of bacterial mortality is grazing by phagocytic protists. Many protists are omnivorous heterotrophs, feeding on a range of different bacterial species. Due to this indiscriminate feeding, different bacterial species can assemble together in the same phagocytic vesicles where they can potentially exchange genetic material...
April 1, 2017: FEMS Microbiology Ecology
https://www.readbyqxmd.com/read/28318795/mechanisms-of-toxic-action-of-silver-nanoparticles-in-the-protozoan-tetrahymena-thermophila-from-gene-expression-to-phenotypic-events
#17
Katre Juganson, Monika Mortimer, Angela Ivask, Sandra Pucciarelli, Cristina Miceli, Kaja Orupõld, Anne Kahru
Silver nanoparticles (AgNPs) are highly toxic to aquatic organisms, however, there is no consensus whether the toxicity is caused solely by released Ag-ions or also by reactive oxygen species (ROS). Here, the effects of protein-coated AgNPs (14.6 nm, Collargol) were studied on viability, oxidative stress and gene expression levels in wild type strains (CU427 and CU428) of ciliate Tetrahymena thermophila. Viability-based 24 h EC50 values of AgNPs were relatively high and significantly different for the two strains: ∼100 mg/L and ∼75 mg/L for CU427 and CU428, respectively...
March 16, 2017: Environmental Pollution
https://www.readbyqxmd.com/read/28301767/progress-in-human-and-tetrahymena-telomerase-structure
#18
Henry Chan, Yaqiang Wang, Juli Feigon
Telomerase is an RNA-protein complex that extends the 3' ends of linear chromosomes, using a unique telomerase reverse transcriptase (TERT) and template in the telomerase RNA (TR), thereby helping to maintain genome integrity. TR assembles with TERT and species-specific proteins, and telomerase function in vivo requires interaction with telomere-associated proteins. Over the past two decades, structures of domains of TR and TERT as well as other telomerase- and telomere-interacting proteins have provided insights into telomerase function...
March 15, 2017: Annual Review of Biophysics
https://www.readbyqxmd.com/read/28287229/stereochemical-investigations-of-the-tetrahymena-cyclase-a-model-system-for-euphane-tirucallane-biosynthesis
#19
José-Luis Giner, Ju Feng
The squalene cyclase of Tetrahymena pyriformis cyclizes 2,3-dihydrosqualene to euph-7-ene. This was used as a model for euphane biosynthesis. D-ring formation was demonstrated to involve pre-chair folding through an experiment with 2,3-dihydro-5-oxasqualene. This requires that a non-least motion rotation (120°) of the C17-20 bond in the intermediate deoxydammaranyl cation occurs before the first 1,2-hydride shift. Truncated substrates relieved the hindrance associated with this rotation and permitted a least motion pathway...
March 13, 2017: Organic & Biomolecular Chemistry
https://www.readbyqxmd.com/read/28273462/negative-regulators-of-an-rnai-heterochromatin-positive-feedback-loop-safeguard-somatic-genome-integrity-in-tetrahymena
#20
Jan H Suhren, Tomoko Noto, Kensuke Kataoka, Shan Gao, Yifan Liu, Kazufumi Mochizuki
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...
March 7, 2017: Cell Reports
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