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Tetrahymena

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https://www.readbyqxmd.com/read/28803330/bime2-a-novel-gene-required-for-interhomolog-meiotic-recombination-in-the-protist-model-organism-tetrahymena
#1
Anura Shodhan, Maria Novatchkova, Josef Loidl
Meiotic recombination is initiated by DNA double-strand breaks (DSBs). Most DSBs are converted into nonreciprocal exchanges (gene conversions) or crossovers (COs) between sister chromatids. Only a minority of DSBs are processed toward interhomolog COs, the precursors of the chiasmata that connect homologous chromosomes. Dmc1, the meiosis-specific paralog of the universal recombination protein Rad51, is required for interhomolog COs; in its absence, univalents are primarily formed. Here, we report a ciliate-specific novel meiotic gene, BIME2, which also promotes interhomolog crossing over...
August 12, 2017: Chromosome Research
https://www.readbyqxmd.com/read/28773114/toxicity-of-nine-doped-rare-earth-metal-oxides-and-respective-individual-metals-to-aquatic-microorganisms-vibrio-fischeri-and-tetrahymena-thermophila
#2
Imbi Kurvet, Katre Juganson, Heiki Vija, Mariliis Sihtmäe, Irina Blinova, Guttorm Syvertsen-Wiig, Anne Kahru
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...
July 5, 2017: Materials
https://www.readbyqxmd.com/read/28735853/a-comparative-study-of-genome-organization-and-epigenetic-mechanisms-in-model-ciliates-with-an-emphasis-on-tetrahymena-paramecium-and-oxytricha
#3
REVIEW
Yurui Wang, Yuanyuan Wang, Yalan Sheng, Jie Huang, Xiao Chen, Khaled A S Al-Rasheid, Shan Gao
As a group of unicellular eukaryotes, ciliates offer a unique system to explore epigenetic regulation, mostly due to their nuclear dualism. Ciliates launched a successful radiation after their early evolutionary branching, therefore harboring an unexpectedly rich pool of diverse biological functions and mechanisms. In this review, we compare distinct features of different ciliates in mating type determination, genome organization, DNA methylation, and removal of internal eliminated sequences (IES), with emphasis on Tetrahymena, Paramecium and Oxytricha...
July 1, 2017: European Journal of Protistology
https://www.readbyqxmd.com/read/28732250/structural-biology-of-telomerase-and-its-interaction-at-telomeres
#4
REVIEW
Yaqiang Wang, Juli Feigon
Telomerase is an RNP that synthesizes the 3' ends of linear chromosomes and is an important regulator of telomere length. It contains a single long non-coding telomerase RNA (TER), telomerase reverse transcriptase (TERT), and other proteins that vary among organisms. Recent progress in structural biology of telomerase includes reports of the first cryo-electron microscopy structure of telomerase, from Tetrahymena, new crystal structures of TERT domains, telomerase RNA structures and models, and identification in Tetrahymena telomerase holoenzyme of human homologues of telomere-associated proteins that have provided a more unified view of telomerase interaction at telomeres as well as insights into the role of telomerase RNA in activity and assembly...
July 18, 2017: Current Opinion in Structural Biology
https://www.readbyqxmd.com/read/28730449/rational-engineering-of-a-modular-group-i-ribozyme-to-control-its-activity-by-self-dimerization
#5
Takahiro Tanaka, Yoshiya Ikawa, Shigeyoshi Matsumura
We designed and constructed a dimer of the Tetrahymena group I ribozyme the activity of which is regulated by self-dimerization. This dimer was rationally designed by utilizing the P5abc and ΔP5abc domains as large RNA motifs. This strategy enabled us to install large ribozyme functions into an RNA structure. This is a step toward expanding the field of RNA nanotechnology beyond the limitation of using only relatively small functional motifs. Self-dimerization can also be rationally programmed by modular engineering of RNA interaction motifs...
2017: Methods in Molecular Biology
https://www.readbyqxmd.com/read/28726394/human-cst-prefers-g-rich-but-not-necessarily-telomeric-sequences
#6
Robert A Hom, Deborah S Wuttke
The human CST (CTC1-STN1-TEN1) heterotrimeric complex plays roles in both telomere maintenance and DNA replication through its ability to interact with single-stranded DNA (ssDNA) of a variety of sequences. The precise sequence specificity required to execute these functions is unknown. Telomere-binding proteins have been shown to specifically recognize key telomeric sequence motifs within ssDNA while accommodating nonspecifically recognized sequences through conformationally plastic interfaces. To better understand the role CST plays in these processes, we have produced a highly purified heterotrimer and elucidated the sequence requirements for CST recognition of ssDNA in vitro...
August 15, 2017: Biochemistry
https://www.readbyqxmd.com/read/28715961/genetics-and-epigenetics-of-mating-type-determination-in-paramecium-and-tetrahymena
#7
Eduardo Orias, Deepankar Pratap Singh, Eric Meyer
While sex is an ancient and highly conserved eukaryotic invention, self-incompatibility systems such as mating types or sexes appear to be derived limitations that show considerable evolutionary plasticity. Within a single class of ciliates, Paramecium and Tetrahymena species have long been known to present a wide variety of mating type numbers and modes of inheritance, but only recently have the genes involved been identified. Although similar transmembrane proteins mediate self/nonself recognition in both ciliates, the mechanisms of mating type determination differ widely, ranging from Mendelian systems to developmental nuclear differentiation, either stochastic or maternally inherited...
July 17, 2017: Annual Review of Microbiology
https://www.readbyqxmd.com/read/28702015/inhibition-of-the-rumen-ciliate-entodinium-caudatum-by-antibiotics
#8
Tansol Park, Tea Meulia, Jeffrey L Firkins, Zhongtang Yu
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...
2017: Frontiers in Microbiology
https://www.readbyqxmd.com/read/28692189/diversification-of-hp1-like-chromo-domain-proteins-in-tetrahymena-thermophila
#9
Emily A Wiley, Scott Horrell, Alyssa Yoshino, Cara C Schornak, Claire Bagnani, Douglas L Chalker
Proteins that possess a chromo domain are well-known for their roles in heterochromatin assembly and maintenance. The Heterochromatin Protein 1 (HP1) family, with a chromo domain and carboxy-terminal chromo shadow domain, targets heterochromatin through interaction with histone H3 methylated on lysine 9 (H3K9me2/3). The structural and functional diversity of these proteins observed in both fission yeast and metazoans correlate with chromatin specialization. To expand these studies, we examined chromo domain proteins in the ciliate Tetrahymena thermophila, which has functionally diverse and developmentally regulated heterochromatin domains...
July 10, 2017: Journal of Eukaryotic Microbiology
https://www.readbyqxmd.com/read/28685161/behavioral-effects-of-a-chemorepellent-receptor-knockout-mutation-in-tetrahymena-thermophila
#10
Dianxiong Zou, Todd M Hennessey
A conditioned supernatant from Tetrahymena thermophila contains a powerful chemorepellent for wild-type cells, and a gene called G37 is required for this response. This is the first genomic identification of a chemorepellent receptor in any eukaryotic unicellular organism. This conditioned supernatant factor (CSF) is small (<1 kDa), and its repellent effect is resistant to boiling, protease treatment, and nuclease digestion. External BAPTA eliminated the CSF response, suggesting that Ca(2+) entry is required for the classical avoiding reactions (AR) used for chemorepulsion...
July 2017: MSphere
https://www.readbyqxmd.com/read/28673471/unusual-features-of-non-dividing-somatic-macronuclei-in-the-ciliate-class-karyorelictea
#11
REVIEW
Ying Yan, Anna J Rogers, Feng Gao, Laura A Katz
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. Div-) and develop anew from micronuclei during each asexual division...
May 22, 2017: European Journal of Protistology
https://www.readbyqxmd.com/read/28661023/copper-induced-topology-switching-and-thrombin-inhibition-with-telomeric-dna-g-quadruplexes
#12
David Maximilian Engelhard, Julia Nowack, Guido H Clever
The topological diversity of DNA G-quadruplexes may play a crucial role in its biological function. Reversible control over a specific folding topology was achieved by the synthesis of a chiral, glycol-based pyridine ligand, and its fourfold incorporation into human telomeric DNA. Square-planar coordination to a CuII ion led to the formation of a highly stabilizing intramolecular metal-base tetrad, thus substituting one G-tetrad in the parent unimolecular G-quadruplex, as characterized by UV-Vis and circular dichroism (CD) spectroscopy, and thermal denaturation experiments (ΔTm = +23 °C)...
June 29, 2017: Angewandte Chemie
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
#13
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
#14
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
#15
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
#16
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 23, 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
#17
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
#18
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%C3%A2-i-ribozymes-enabling-exon-recombination-through-pairs-of-cooperative-trans-splicing-reactions
#19
Takahiro Tanaka, Yusuke Hirata, Yuto Tominaga, Hiroyuki Furuta, Shigeyoshi Matsumura, Yoshiya Ikawa
Group I (GI) self-splicing ribozymes are attractive tools for biotechnology and synthetic biology. Several trans-splicing and related reactions based on GI ribozymes have been developed for the purpose of recombining their target mRNA sequences. By combining trans-splicing systems with rational modular engineering of GI ribozymes it was possible to achieve more complex editing of target RNA sequences. In this study we have developed a cooperative trans-splicing system through rational modular engineering with use of dimeric GI ribozymes derived from the Tetrahymena group I intron ribozyme...
August 17, 2017: Chembiochem: a European Journal of Chemical Biology
https://www.readbyqxmd.com/read/28509379/microbial-eukaryotes-that-lack-sterols
#20
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
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