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Masaki Edamatsu
Mutational analyses of axonemal dyneins are useful for elucidating the molecular mechanism of ciliary motility. This study demonstrates a mutation system for characterizing lethal P-loop mutations in Tetrahymena outer arm dynein (Dyh3p). The viable DYH3-knockout (vKO-DYH3) cells isolated in this study enabled the examination of lethal mutations in P-loops 1 and 2. The P1 mutant dynein localized in the oral apparatus and the proximal region of the cilia, and the P2 mutant dynein localized only in the oral apparatus...
February 6, 2018: Biochemical and Biophysical Research Communications
Amanda K Mennie, Bettina A Moser, Toru M Nakamura
Telomerase is a reverse transcriptase complex that ensures stable maintenance of linear eukaryotic chromosome ends by overcoming the end replication problem, posed by the inability of replicative DNA polymerases to fully replicate linear DNA. The catalytic subunit TERT must be assembled properly with its telomerase RNA for telomerase to function, and studies in Tetrahymena have established that p65, a La-related protein 7 (LARP7) family protein, utilizes its C-terminal xRRM domain to promote assembly of the telomerase ribonucleoprotein (RNP) complex...
February 8, 2018: Nature Communications
Laura C Collopy, Tracy L Ware, Tomas Goncalves, Sunnvør Í Kongsstovu, Qian Yang, Hanna Amelina, Corinne Pinder, Ala Alenazi, Vera Moiseeva, Siân R Pearson, Christine A Armstrong, Kazunori Tomita
Understanding the intricacies of telomerase regulation is crucial due to the potential health benefits of modifying its activity. Telomerase is composed of an RNA component and reverse transcriptase. However, additional factors required during biogenesis vary between species. Here we have identified fission yeast Lar7 as a member of the conserved LARP7 family, which includes the Tetrahymena telomerase-binding protein p65 and human LARP7. We show that Lar7 has conserved RNA-recognition motifs, which bind telomerase RNA to protect it from exosomal degradation...
February 8, 2018: Nature Communications
Wei Miao, Jing Zhang, Guanxiong Yan, Miao Tian, Yang Ma, Jie Xiong
Evolutionarily conserved E2F family transcription factors regulate the cell cycle via controlling gene expression in a wide range of eukaryotes. We previously demonstrated that the meiosis-specific transcription factor E2fl1 had an important role in meiosis in the model ciliate Tetrahymena thermophila. Here, we report that expression of another E2F family transcription factor gene DPL2 correlates highly with that of E2FL1. Similar to e2fl1Δ cells, dpl2Δ cells undergo meiotic arrest prior to anaphase I, with the five chromosomes adopting an abnormal tandem arrangement...
February 8, 2018: Cell Cycle
Huanxin Zhou, Jing Xu, Wei Wang
Metallothioneins (MTs) are low-molecular-weight proteins with high Cys content and high metal-chelating ability. CdMT and CuMT subfamilies present different characteristics in Tetrahymena. To explore the effect of the cysteine arrangement and sequence length of MTs for binding different metal ions, MTT1, truncated MTT1 (TM1), MTT2, and truncated MTT2 (TM2) were expressed in E. coli. The half-maximal inhibiting concentrations (IC50) of Cd2+ and Cu+ for the recombinant strains were different. Furthermore, E. coli cells expressing MTT1 and TM1 exhibited higher accumulating ability for Cd2+ than cells expressing MTT2 and TM2...
February 5, 2018: Bioscience, Biotechnology, and Biochemistry
Ying Wang, Monika Mortimer, Chong Hyun Chang, Patricia A Holden
Robust evaluation of potential environmental and health risks of carbonaceous and boron nitride nanomaterials (NMs) is imperative. However, significant agglomeration of pristine carbonaceous and boron nitride NMs due to strong van der Waals forces renders them not suitable for direct toxicity testing in aqueous media. Here, the natural polysaccharide alginic acid (AA) was used as a nontoxic, environmentally relevant dispersant with defined composition to disperse seven types of carbonaceous and boron nitride NMs, including multiwall carbon nanotubes, graphene, boron nitride nanotubes, and hexagonal boron nitride flakes, with various physicochemical characteristics...
January 30, 2018: Nanomaterials
D H Lynn, F P Doerder, P L Gillis, R S Prosser
A ciliate protozoan was discovered whose presence coincided with a rapid decrease in the viability (i.e. ability to close valves) of glochidia of the freshwater mussel Lampsilis siliquoidea. Microscopic examination showed it to be a histophagous tetrahymenine ciliate. Small subunit (SSU) rRNA and cytochrome c oxidase subunit 1 (cox1) barcode sequences from cultured cells showed that it belongs to the same new species isolated from water samples as a free-living ciliate. Phylogenetic analyses place this new ciliate in the same clade with the macrostome species Tetrahymena paravorax, and we propose the name T...
January 31, 2018: Diseases of Aquatic Organisms
Chang Ho Lee, Seung Ryul Han, Seong-Wook Lee
Since the breakthrough discovery of catalytic RNAs (ribozymes) in the early 1980s, valuable ribozyme-based gene therapies have been developed for incurable diseases ranging from genetic disorders to viral infections and cancers. Ribozymes can be engineered and used to downregulate or repair pathogenic genes via RNA cleavage mediated by trans-cleaving ribozymes or repair and reprograming mediated by trans-splicing ribozymes, respectively. Uniquely, trans-splicing ribozymes can edit target RNAs via simultaneous destruction and repair (and/or reprograming) to yield the desired therapeutic RNAs, thus selectively inducing therapeutic gene activity in cells expressing the target RNAs...
January 31, 2018: Wiley Interdisciplinary Reviews. RNA
Lisa Siegmund, Michael Schweikert, Martin S Fischer, Johannes Wöstemeyer
Endosymbiotic interactions are frequently found in nature, especially in the group of protists. Even though many endosymbioses have been studied in detail, little is known about the mechanistic origins and physiological prerequisites of endosymbiont establishment. A logical step towards the development of endocytobiotic associations is evading digestion and escaping from the host's food vacuoles. Surface properties of bacteria are probably involved in these processes. Therefore, we chemically modified the surface of a transformant strain of Escherichia coli prior to feeding to Tetrahymena pyriformis...
January 27, 2018: Journal of Eukaryotic Microbiology
Mst Ara Gulshan, Md Motiar Rahman, Shigeyoshi Matsumura, Tsunehiko Higuchi, Naoki Umezawa, Yoshiya Ikawa
Group I intron ribozymes share common core elements that form a three-dimensional structure responsible for their catalytic activity. This core structure is unstable without assistance from additional factors that stabilize its tertiary structure. We examined biogenic triamine and tetraamine and also their fragments for their abilities to stabilize a structurally unstable group I ribozyme, ΔP5 ribozyme, derived from the Tetrahymena group I intron ribozyme by deleting its large activator module. Biogenic triamine (spermidine) and tetraamine (spermine) efficiently activated the ΔP5 ribozyme under conditions where the ribozyme was virtually inactive...
January 12, 2018: Biochemical and Biophysical Research Communications
Xyrus X Maurer-Alcalá, Rob Knight, Laura A Katz
Separate germline and somatic genomes are found in numerous lineages across the eukaryotic tree of life, often separated into distinct tissues (e.g., in plants, animals, and fungi) or distinct nuclei sharing a common cytoplasm (e.g., in ciliates and some foraminifera). In ciliates, germline-limited (i.e., micronuclear-specific) DNA is eliminated during the development of a new somatic (i.e., macronuclear) genome in a process that is tightly linked to large-scale genome rearrangements, such as deletions and reordering of protein-coding sequences...
January 9, 2018: MBio
Bin Huang, Shuai Yan, Lin Xiao, Rong Ji, Liuyan Yang, Ai-Jun Miao, Ping Wang
Imaging and quantification of nanoparticles in single cells in their most natural condition are expected to facilitate the biotechnological applications of nanoparticles and allow for better assessment of their biosafety risks. However, current imaging modalities either require tedious sample preparation or only apply to nanoparticles with specific physicochemical characteristics. Here, the emerging hyperspectral stimulated Raman scattering (SRS) microscopy, as a label-free and nondestructive imaging method, is used for the first time to investigate the subcellular distribution of nanoparticles in the protozoan Tetrahymena thermophila...
December 28, 2017: Small
Nicholas Rhind
Unstable Accumulating Activator models for cellular size control propose an activator that accumulates in a size-dependent manner and triggers cell cycle progression once it has reached a certain threshold. Having a short half life makes such an activator responsive to changes in cell size and makes specific predictions for how cells respond to perturbation. In particular, it explains the curious phenomenon of excess mitotic delay. Excess mitotic delay, first observed in Tetrahymena in the '50s, is a phenomenon in which a pulse of protein synthesis inhibition causes a delay in mitotic entry that is longer than the pulse and that gets longer the later in the cell cycle the pulse is delivered...
December 28, 2017: BioEssays: News and Reviews in Molecular, Cellular and Developmental Biology
Dennis G Searcy
Eukaryotic nucleocytoplasm is believed to be descended from ancient Archaea that respired on elemental sulfur. If so, a vestige of sulfur reduction might persist in modern eukaryotic cells. That was tested in Tetrahymena thermophila, chosen as a model organism. When oxygenated, the cells consumed H2S rapidly, but when made anoxic they produced H2S mostly by amino acid catabolism. That could be inhibited by adding aminooxyacetic acid, and then H2S production from elemental sulfur became more evident. Anoxic cell lysates produced H2S when provided with sulfur and NADH, but not with either substrate alone...
December 2, 2017: European Journal of Protistology
Rachel Howard-Till, Josef Loidl
Condensin is a protein complex with diverse functions in chromatin packaging and chromosome condensation and segregation. We studied condensin in the evolutionarily distant protist model Tetrahymena, which features non-canonical nuclear organization and divisions. In Tetrahymena, the germline and soma are partitioned into two different nuclei within a single cell. Consistent with their functional specializations in sexual reproduction and gene expression, condensins of the germline nucleus and the polyploid somatic nucleus are composed of different subunits...
December 13, 2017: Molecular Biology of the Cell
Anoop Narayana Pillai, Sushmita Shukla, Sudhanshu Gautam, Abdur Rahaman
Phosphatidate phosphatases (PAH) play a central role in lipid metabolism and intracellular signaling. Herein, we report the presence of a low-molecular-weight PAH homolog in the single-celled ciliate Tetrahymena thermophila. In vitro phosphatase assay showed that TtPAH2 belongs to the magnesium-dependent phosphatidate phosphatase (PAP1) family. Loss of function of TtPAH2 did not affect the growth of Tetrahymena. Unlike other known PAH homologs, TtPAH2 did not regulate lipid droplet number and ER morphology...
December 2017: Journal of Biosciences
Shaon Chakrabarti, Changbong Hyeon, Xiang Ye, George H Lorimer, D Thirumalai
Molecular chaperones facilitate the folding of proteins and RNA in vivo. Under physiological conditions, the in vitro folding of Tetrahymena ribozyme by the RNA chaperone CYT-19 behaves paradoxically; increasing the chaperone concentration reduces the yield of native ribozymes. In contrast, the protein chaperone GroEL works as expected; the yield of the native substrate increases with chaperone concentration. The discrepant chaperone-assisted ribozyme folding thus contradicts the expectation that it operates as an efficient annealing machine...
December 7, 2017: Proceedings of the National Academy of Sciences of the United States of America
Patricia de Francisco, Ana Martín-González, Aaron P Turkewitz, Juan Carlos Gutiérrez
Metallothioneins (MT) constitute a superfamily of small cytosolic proteins that are able to bind metal cations through numerous cysteine (Cys) residues. Like other organisms the ciliate Tetrahymena thermophila presents several MT isoforms, which have been classified into two subfamilies (Cd- and Cu-metallothioneins). The main aim of this study was to examine the specific functions and transcriptional regulation of the five MT isoforms present in T. thermophila, by using several strains of this ciliate. After a laboratory evolution experiment over more than two years, three different T...
2017: PloS One
María Jesús Andrés-Costa, Kathryn Proctor, Marco T Sabatini, Anthony P Gee, Simon E Lewis, Yolanda Pico, Barbara Kasprzyk-Hordern
European legislation focusing on water quality is expected to broaden to encompass several pharmaceuticals as priority hazardous substances. This manuscript aims to challenge current regulatory approaches that do not recognize stereochemistry of chiral pharmaceuticals by testing the hypothesis that environmental transformation and effects of chiral pharmaceuticals are stereoselective. Our experiments revealed that, while degradation of chiral fluoxetine (FL) in river water occurs via non-enantioselective photochemical and mildly-enantioselective microbial processes favoring the (R)-enantiomer, a pronounced enantioselectivity favoring (S)-FL (leading to the formation of (S)-NFL (norfluoxetine)) is observed during activated sludge treatment...
November 17, 2017: Scientific Reports
Cecília Seixas, João Gonçalves, Luís Viseu Melo, Helena Soares
Cilia are complex and dynamic organelles that have motility and sensory functions. Defects in cilia biogenesis and function are at the origin of human ciliopathies. In motile cilia, a basal body organizes the axoneme composed of nine microtubule doublets surrounding a central pair of singlet microtubules. The distal ends of axonemal microtubules are attached to the membrane by microtubule-capping structures. Little is known about the early steps of cilium assembly. Although cilia grow and resorb from their distal tips, it remains poorly understood where and when the components of the caps are first assembled...
October 20, 2017: Protist
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