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Tetrahymena

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https://www.readbyqxmd.com/read/28335309/separation-of-bacteria-protozoa-and-carbon-nanotubes-by-density-gradient-centrifugation
#1
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
#2
Iqbal Aijaz, Gerald B Koudelka
The microbial communities in natural environments such as soil, pond water, or animal rumens are comprised 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 can they potentially exchange genetic material...
March 3, 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
#3
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
#4
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
#5
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
#6
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
https://www.readbyqxmd.com/read/28238660/structure-function-studies-link-class-ii-viral-fusogens-with-the-ancestral-gamete-fusion-protein-hap2
#7
Jennifer Fricke Pinello, Alex L Lai, Jean K Millet, Donna Cassidy-Hanley, Jack H Freed, Theodore G Clark
The conserved transmembrane protein, HAP2/GCS1, has been linked to fertility in a wide range of taxa and is hypothesized to be an ancient gamete fusogen. Using template-based structural homology modeling, we now show that the ectodomain of HAP2 orthologs from Tetrahymena thermophila and other species adopt a protein fold remarkably similar to the dengue virus E glycoprotein and related class II viral fusogens. To test the functional significance of this predicted structure, we developed a flow-cytometry-based assay that measures cytosolic exchange across the conjugation junction to rapidly probe the effects of HAP2 mutations in the Tetrahymena system...
March 6, 2017: Current Biology: CB
https://www.readbyqxmd.com/read/28216593/biomethylation-and-volatilization-of-arsenic-by-model-protozoan-tetrahymena-pyriformis-under-different-phosphate-regimes
#8
Xixiang Yin, Lihong Wang, Zhanchao Zhang, Guolan Fan, Jianjun Liu, Kaizhen Sun, Guo-Xin Sun
Tetrahymena pyriformis, a freshwater protozoan, is common in aquatic systems. Arsenic detoxification through biotransformation by T. pyriformis is important but poorly understood. Arsenic metabolic pathways (including cellular accumulation, effluxion, biomethylation, and volatilization) of T. pyriformis were investigated at various phosphate concentrations. The total intracellular As concentration increased markedly as the external phosphate concentration decreased. The highest concentration was 168.8 mg·kg(-1) dry weight, after exposure to As(V) for 20 h...
February 14, 2017: International Journal of Environmental Research and Public Health
https://www.readbyqxmd.com/read/28212786/interplay-between-microbial-trait-dynamics-and-population-dynamics-revealed-by-the-combination-of-laboratory-experiment-and-computational-approaches
#9
Kenta Suzuki, Yuji Yamauchi, Takehito Yoshida
Filament formation is a common bacterial defense mechanism and possibly has a broad impact on microbial community dynamics. In order to examine the impact of filament formation on population dynamics, we developed an experimental system with a filamentous bacterium Flectobacillus sp. MWH38 and a ciliate predator Tetrahymena pyriformis. In this system, the effective defense of Flectobacillus resulted in the extinction of Tetrahymena by allowing almost no population growth. The result of a kairomone experiment suggested the existence of chemical signals for filament formation...
February 16, 2017: Journal of Theoretical Biology
https://www.readbyqxmd.com/read/28190732/the-macronuclear-genome-of-stentor-coeruleus-reveals-tiny-introns-in-a-giant-cell
#10
Mark M Slabodnick, J Graham Ruby, Sarah B Reiff, Estienne C Swart, Sager Gosai, Sudhakaran Prabakaran, Ewa Witkowska, Graham E Larue, Susan Fisher, Robert M Freeman, Jeremy Gunawardena, William Chu, Naomi A Stover, Brian D Gregory, Mariusz Nowacki, Joseph Derisi, Scott W Roy, Wallace F Marshall, Pranidhi Sood
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]...
February 20, 2017: Current Biology: CB
https://www.readbyqxmd.com/read/28182957/heteroagglomeration-of-zinc-oxide-nanoparticles-with-clay-mineral-modulates-the-bioavailability-and-toxicity-of-nanoparticle-in-tetrahymena-pyriformis
#11
Govind Sharan Gupta, Violet Aileen Senapati, Alok Dhawan, Rishi Shanker
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 (p<0.05) increases the hydrodymic size of clay particles from 1652±90nm to 2158±13nm due to heteroagglomeration. The electrokinetic measurements showed a significant (p<0...
June 1, 2017: Journal of Colloid and Interface Science
https://www.readbyqxmd.com/read/28153088/specific-and-efficient-regression-of-cancers-harboring-kras-mutation-by-targeted-rna-replacement
#12
Sung Jin Kim, Ju Hyun Kim, Bitna Yang, Jin-Sook Jeong, Seong-Wook Lee
Mutations in the KRAS gene, which persistently activate RAS function, are most frequently found in many types of human cancers. Here, we proposed and verified a new approach against cancers harboring the KRAS mutation with high cancer selectivity and efficient anti-cancer effects based on targeted RNA replacement. To this end, trans-splicing ribozymes from Tetrahymena group I intron were developed, which can specifically target and reprogram the mutant KRAS G12V transcript to induce therapeutic gene activity in cells...
February 1, 2017: Molecular Therapy: the Journal of the American Society of Gene Therapy
https://www.readbyqxmd.com/read/28135687/n-6-methyladenine-dna-modification-in-the-unicellular-eukaryotic-organism-tetrahymena-thermophila
#13
Yuanyuan Wang, Yalan Sheng, Yongqiang Liu, Bo Pan, Jie Huang, Alan Warren, Shan Gao
N(6)-methyladenine DNA (6mA) modification exists in both prokaryotes and eukaryotes in which it plays a crucial role in regulating numerous biological processes. In prokaryotes, 6mA is a marker to distinguish self from foreign DNA. Its role in eukaryotes, however, remains elusive. Ciliates were among the first eukaryotes reported to contain 6mA. In the model organism T. thermophila, cellular localization and features of 6mA have been extensively studied, especially in ribosomal DNA (rDNA) molecules. Here, we summarize the features and potential functions of 6mA in Tetrahymena thermophila and other ciliates, and the major findings and contributions of the Tetrahymena model in studies of 6mA methylation...
December 23, 2016: European Journal of Protistology
https://www.readbyqxmd.com/read/28123910/a-comparative-in-silico-analysis-of-autophagy-proteins-in-ciliates
#14
Erhan Aslan, Nurçin Küçükoğlu, Muhittin Arslanyolu
Autophagy serves as a turnover mechanism for the recycling of redundant and/or damaged macromolecules present in eukaryotic cells to re-use them under starvation conditions via a double-membrane structure known as autophagosome. A set of eukaryotic genes called autophagy-related genes (ATGs) orchestrate this highly elaborative process. The existence of these genes and the role they play in different eukaryotes are well-characterized. However, little is known of their role in some eukaryotes such as ciliates...
2017: PeerJ
https://www.readbyqxmd.com/read/28119814/structure-of-the-40s-ribosomal-subunit-of-plasmodium-falciparum-by-homology-and-de-novo-modeling
#15
Harrison Ndung'u Mwangi, Peter Wagacha, Peterson Mathenge, Fredrick Sijenyi, Francis Mulaa
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...
January 2017: Acta Pharmaceutica Sinica. B
https://www.readbyqxmd.com/read/28110783/identification-of-novel-virulence-related-genes-in-aeromonas-hydrophila-by-screening-transposon-mutants-in-a-tetrahymena-infection-model
#16
Maoda Pang, Xing Xie, Yuhao Dong, Hechao Du, Nannan Wang, Chengping Lu, Yongjie Liu
Outbreaks of motile Aeromonad septicemia (MAS) in fish caused by sequence type (ST) 251 Aeromonas hydrophila have become a prominent problem for the aquaculture industry. The pathogenesis of A. hydrophila is very complicated, and some virulence factors remain to be identified. In this study, to identify novel virulence-related factors, ST251 A. hydrophila strain NJ-35 was used as the parental strain to construct a mutant library comprising 1030 mutant strains by transposon insertion mutagenesis. Subsequently, 33 virulence-attenuated transposon insertion mutants were identified using Tetrahymena and zebrafish as model hosts in sequence...
February 2017: Veterinary Microbiology
https://www.readbyqxmd.com/read/28100637/a-zip3-like-protein-plays-a-role-in-crossover-formation-in-the-sc-less-meiosis-of-the-protist-tetrahymena
#17
Anura Shodhan, Kensuke Kataoka, Kazufumi Mochizuki, Maria Novatchkova, Josef Loidl
When programmed meiotic DNA double-strand breaks (DSBs) undergo recombinational repair, genetic crossovers (COs) may be formed. A certain level of these are required for the faithful segregation of chromosomes, but the majority of DSBs are processed toward a safer alternative, namely non-crossovers (NCOs), via non-reciprocal DNA exchange. At the crossroads between these two DSB fates are the Msh4-Msh5 (MutSγ) complex, which stabilizes CO-destined recombination intermediates, and members of the Zip3/RNF212 family of RING finger proteins, which in turn stabilize MutSγ...
January 18, 2017: Molecular Biology of the Cell
https://www.readbyqxmd.com/read/28096453/programmable-formation-of-catalytic-rna-triangles-and-squares-by-assembling-modular-rna-enzymes
#18
Hiroki Oi, Daisuke Fujita, Yuki Suzuki, Hiroshi Sugiyama, Masayuki Endo, Shigeyoshi Matsumura, Yoshiya Ikawa
RNA is a biopolymer that is attractive for constructing nanoscale objects with complex structures. Three-dimensional (3D) structures of naturally occurring RNAs often have modular architectures. The 3D structure of a group I (GI) ribozyme from Tetrahymena has a typical modular architecture, which can be separated into two structural modules (ΔP5 and P5abc). The fully active ribozyme can be reconstructed by assembling the two separately prepared modules through highly specific and strong assembly between ΔP5 ribozyme and P5abc RNA...
January 17, 2017: Journal of Biochemistry
https://www.readbyqxmd.com/read/28096444/single-molecule-fret-rosetta-reveals-rna-structural-rearrangements-during-human-telomerase-catalysis
#19
Joseph W Parks, Kalli Kappel, Rhiju Das, Michael D Stone
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...
February 2017: RNA
https://www.readbyqxmd.com/read/28087716/the-piggybac-transposon-derived-genes-tpb1-and-tpb6-mediate-essential-transposon-like-excision-during-the-developmental-rearrangement-of-key-genes-in-tetrahymena-thermophila
#20
Chao-Yin Cheng, Janet M Young, Chih-Yi Gabriela Lin, Ju-Lan Chao, Harmit S Malik, Meng-Chao Yao
Ciliated protozoans perform extreme forms of programmed somatic DNA rearrangement during development. The model ciliate Tetrahymena thermophila removes 34% of its germline micronuclear genome from somatic macronuclei by excising thousands of internal eliminated sequences (IESs), a process that shares features with transposon excision. Indeed, piggyBac transposon-derived genes are necessary for genome-wide IES excision in both Tetrahymena (TPB2 [Tetrahymena piggyBac-like 2] and LIA5) and Paramecium tetraurelia (PiggyMac)...
December 15, 2016: Genes & Development
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