| distinct functional roles of β-tubulin isotypes in microtubule arrays of tetrahymena thermophila, a model single-celled organism. | 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 ... | 2012 | 22745812 |
| rna folding and catalysis mediated by iron (ii). | 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 th ... | 2012 | 22701543 |
| structure and mechanism of a canonical poly(adp-ribose) glycohydrolase. | poly(adp-ribosyl)ation is a reversible post-translational protein modification involved in the regulation of a number of cellular processes including dna repair, chromatin structure, mitosis, transcription, checkpoint activation, apoptosis and asexual development. the reversion of poly(adp-ribosyl)ation is catalysed by poly(adp-ribose) (par) glycohydrolase (parg), which specifically targets the unique par (1''-2') ribose-ribose bonds. here we report the structure and mechanism of the first canon ... | 2012 | 22673905 |
| folding path of p5abc rna involves direct coupling of secondary and tertiary structures. | folding mechanisms in which secondary structures are stabilized through the formation of tertiary interactions are well documented in protein folding but challenge the folding hierarchy normally assumed for rna. however, it is increasingly clear that rna could fold by a similar mechanism. p5abc, a small independently folding tertiary domain of the tetrahymena thermophila group i ribozyme, is known to fold by a secondary structure rearrangement involving helix p5c. however, the extent of this rea ... | 2012 | 22641849 |
| experimental evidence of false-positive comet test results due to tio2 particle--assay interactions. | 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 ... | 2013 | 22632608 |
| subcellular localization and role of ran1 in tetrahymena thermophila amitotic macronucleus. | amitosis, a direct method of cell division is common in ciliated protozoan, fungi and some animal and plant cells. during amitosis, intranuclear microtubules are reorganized into specified arrays which assist in separation of nucleus, despite lack of a bipolar spindle. however, the regulation of amitosis is not understood. here, we focused on the localization and role of mitotic spindle assembly regulator: ran gtpase (ran1) in macronuclear amitosis in binucleated protozoan tetrahymena thermophil ... | 2012 | 22594798 |
| heterogeneity of dynein structure implies coordinated suppression of dynein motor activity in the axoneme. | axonemal dyneins provide the driving force for flagellar/ciliary bending. nucleotide-induced conformational changes of flagellar dynein have been found both in vitro and in situ by electron microscopy, and in situ studies demonstrated the coexistence of at least two conformations in axonemes in the presence of nucleotides (the apo and the nucleotide-bound forms). the distribution of the two forms suggested cooperativity between adjacent dyneins on axonemal microtubule doublets. although the mech ... | 2012 | 22569523 |
| acclimation of tetrahymena thermophila to bulk and nano-tio2 particles by changes in membrane fatty acids saturation. | we provide experimental evidence that changes in the membrane fatty acid profile of tetrahymena thermophila incubated with nano- or bulk tio(2) particle are not accompanied by ros generation or lipid peroxidation. consequently these changes are interpreted as acclimation to unfavorable conditions and not as toxic effects. t. thermophila cells were exposed to tio(2) particles at different concentrations for 24h at 32°c. treatment of cultures with nano- and bulk tio(2) particles resulted in change ... | 2012 | 22551634 |
| purification and partial characterization of glyceraldehyde-3-phosphate dehydrogenase from the ciliate tetrahymena thermophila. | in the present study, we purified the glycolytic enzyme glyceraldehyde-3-phosphate dehydrogenase (gapdh) which is involved in cellular energy production and has important housekeeping functions, from the ciliate tetrahymena thermophila using a three-step procedure. the enzyme was purified ~68 folds by ammonium sulfate precipitation, followed by two steps of column chromatography (deae-cellulose and mono-s). the purified enzyme is a homotetramer with a molecular weight of ~120 kda. isoelectric fo ... | 2012 | 22543501 |
| an essential role for the dna breakage-repair protein ku80 in programmed dna rearrangements in tetrahymena thermophila. | programmed dna rearrangements are important processes present in many organisms. in the ciliated protozoan tetrahymena thermophila, dna rearrangements occur during the sexual conjugation process and lead to the deletion of thousands of specific dna segments and fragmentation of the chromosomes. in this study, we found that the ku80 homologue, a conserved component of the nonhomologous end-joining process of dna repair, was essential for these two processes. during conjugation, tku80 was highly e ... | 2012 | 22513090 |
| purification of tetrahymena cytoskeletal proteins. | like all eukaryotic cells, tetrahymena thermophila contains a rich array of cytoskeletal proteins, some familiar and some novel. a detailed analysis of the structure, function, and interactions of these proteins requires procedures for purifying the individual protein components. procedures for the purification of actin and tubulin from tetrahymena are reviewed, followed by a description of a procedure that yields proteins from the epiplasmic layer and associated structures, including the tetrin ... | 2012 | 22444153 |
| cytological analysis of tetrahymena thermophila. | since their first detection in pond water, large ciliates such as tetrahymena thermophila, have captivated school children and scientists alike with the elegance of their swimming and the beauty of their cortical organization. indeed, cytology - simply looking at cells - is an important component of most areas of study in cell biology and is particularly intriguing in the large, complex tetrahymena cell. cytological analysis of tetrahymena is critical for the study of the microtubule cytoskeleto ... | 2012 | 22444152 |
| biochemical approaches including the design and use of strains expressing epitope-tagged proteins. | 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 affinit ... | 2012 | 22444151 |
| tetrahymena thermophila genetics: concepts and applications. | the differentiation of germline and somatic genomes in tetrahymena thermophila results in two independent systems of genetic transmission. one is the conserved, sexual mendelian genetics system of the germline genome. the other is a random genetic assortment mechanism, which operates in the somatic genome during asexual propagation. this chapter describes both systems, their interplay, and how they are exploited to construct useful biological reagents and powerful tools, which can be used to ans ... | 2012 | 22444149 |
| natural populations and inbred strains of tetrahymena. | tetrahymena typically is found in freshwater lakes, ponds, and streams in association with submerged or emergent vegetation. the genus consists of numerous breeding species with micronuclei and many asexual species without micronuclei. in summer months when most populations are at their peak, 30-50% of water samples may yield one or more species of tetrahymena. this chapter describes both bulk and trapping procedures for collecting tetrahymena and also evaluates barcode methods for species ident ... | 2012 | 22444148 |
| tetrahymena in the laboratory: strain resources, methods for culture, maintenance, and storage. | the ciliated protozoan tetrahymena thermophila has been an important model system for biological research for many years. during that time, a variety of useful strains, including highly inbred stocks, a collection of diverse mutant strains, and wild cultivars from a variety of geographical locations have been identified. in addition, thanks to the efforts of many different laboratories, optimal conditions for growth, maintenance, and storage of tetrahymena have been worked out. to facilitate the ... | 2012 | 22444147 |
| developmental progression of tetrahymena through the cell cycle and conjugation. | the ciliate tetrahymena thermophila can be said to undergo a variety of developmental programs. during vegetative growth, cells coordinate a variety of cell-cycle operations including macronuclear dna synthesis and a-mitotic fission, micronuclear dna synthesis and mitosis, cytokinesis and an elaborate program of cortical morphogenesis that replicates the cortical organelles. when starved, cells undergo oral replacement, transformation into fast-swimming dispersal forms or, when encountering cell ... | 2012 | 22444146 |
| conservation and innovation in tetrahymena membrane traffic: proteins, lipids, and compartments. | the past decade has seen a significant expansion in our understanding of membrane traffic in tetrahymena thermophila, facilitated by the development of new experimental tools and by the availability of the macronuclear genome sequence. here we review studies on multiple pathways of uptake and secretion, as well as work on metabolism of membrane lipids. we discuss evidence for conservation versus innovation in the mechanisms used in ciliates compared with those in other eukaryotic lineages, and r ... | 2012 | 22444145 |
| from molecules to morphology: cellular organization of tetrahymena thermophila. | tetrahymena thermophila is both a cell and an organism, which combines great intracellular complexity with a remarkable accessibility to investigation using many different approaches. in this review, we start with a description of the elaborate cortical organization of the tetrahymena cell, and then proceed inward to consider the mitochondria and then the nuclei. for each of these cellular organelles and organelle-systems, first we familiarize the reader with its location in the cell and its str ... | 2012 | 22444144 |
| whole genome studies of tetrahymena. | within the past decade, genomic studies have emerged as essential and highly productive tools to explore the biology of tetrahymena thermophila. the current major resources, which have been extensively mined by the research community, are the annotated macronuclear genome assembly, transcriptomic data and the databases that house this information. efforts in progress will soon improve these data sources and expand their scope, including providing annotated micronuclear and comparative genomic se ... | 2012 | 22444143 |
| perspectives on the ciliated protozoan tetrahymena thermophila. | in biology, scientific discoveries are often linked to technical innovations made possible by an inspired choice of model organism. ciliate species, especially tetrahymena thermophila, have had historically significant roles as uniquely enabling experimental systems. more importantly, as the chapters in this volume attest, ongoing efforts of the t. thermophila model organism community have created a knowledge and resource infrastructure for systems-level studies across a whole genome or proteome ... | 2012 | 22444140 |
| tetrahymena thermophila jmjd3 homolog regulates h3k27 methylation and nuclear differentiation. | histone h3k27me3 modification is an important regulator for development and gene expression. in tetrahymena thermophila, the complex chromatin dynamics of h3k27me3 marks during nuclear development suggested that an h3k27me3 demethylase might exist. here, we report an h3k27me3 demethylase homolog, jmj1, in tetrahymena. during conjugation, jmj1 expression is upregulated and the protein is localized first in the parental macronucleus and then in the new macronucleus. in conjugating cells, knockdown ... | 2012 | 22427430 |
| role of atg8 and autophagy in programmed nuclear degradation in tetrahymena thermophila. | autophagy is an evolutionarily conserved mechanism for the degradation of cellular components, but its role in enucleation during differentiation has not been established. tetrahymena thermophila is a unicellular eukaryote with two functionally distinct nuclei, the somatic (macro-) and the germ line (micro-) nuclei. these nuclei are produced during sexual reproduction (conjugation), which involves differentiation and selective degradation of several specific nuclei. to examine the role of autoph ... | 2012 | 22366125 |
| mob1: defining cell polarity for proper cell division. | mob1 is a component of both the mitotic exit network and hippo pathway, being required for cytokinesis, control of cell proliferation and apoptosis. cell division accuracy is crucial in maintaining cell ploidy and genomic stability and relies on the correct establishment of the cell division axis, which is under the control of the cell's environment and its intrinsic polarity. the ciliate tetrahymena thermophila possesses a permanent anterior-posterior axis, left-right asymmetry and divides symm ... | 2012 | 22331360 |
| the c-terminal domain of tetrahymena thermophila telomerase holoenzyme protein p65 induces multiple structural changes in telomerase rna. | 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 st ... | 2012 | 22315458 |
| an in vivo selection method to optimize trans-splicing ribozymes. | group i intron ribozymes can repair mutated mrnas by replacing the 3'-terminal portion of the mrna with their own 3'-exon. this trans-splicing reaction has the potential to treat genetic disorders and to selectively kill cancer cells or virus-infected cells. however, these ribozymes have not yet been used in therapy, partially due to a low in vivo trans-splicing efficiency. previous strategies to improve the trans-splicing efficiencies focused on designing and testing individual ribozyme constru ... | 2012 | 22274958 |
| [alternative splicing of an atp-binding cassette transporter abcc10 in tetrahymena thermophila]. | atp-binding cassette transporters (abct) could generate multiple transcripts through alternative splicing (as) in mammalian. some as introduced ptc (premature terminal codon)-containing isoforms of abct couple with nmd (nonsense-mediated mrna decay) to regulate relevant functions. however, there are no similar reports in lower organisms. this paper focuses on the unicellular protozoa tetrahymena thermophila, based on the rna-seq data of tetrahymena thermophila, identified two alternative splicin ... | 2011 | 22184018 |
| preparation and biological effect of nucleotide-capped cdse/zns quantum dots on tetrahymena thermophila. | in this paper, we described the preparation and characterization of different types of modified cdse/zns quantum dots (qds) and explored the biological effects of qds with different surface modifications on the whole growth of unicellular protozoan tetrahymena thermophila bf(5) using a thermal activity monitor air isothermal microcalorimeter. our results demonstrated that adenosine 5'-monophosphate (amp) showed stronger interaction with qds than other types of nucleotide. amp-qds could stimulate ... | 2012 | 22161288 |
| the rna accordion model for template positioning by telomerase rna during telomeric dna synthesis. | telomerase is a ribonucleoprotein (rnp) enzyme that maintains the ends of linear eukaryotic chromosomes and whose activation is a hallmark of 90% of all cancers. this rnp minimally contains a reverse transcriptase protein subunit (tert) that catalyzes telomeric dna synthesis and an rna subunit (ter) that has templating, architectural and protein-scaffolding roles. telomerase is unique among polymerases in that it synthesizes multiple copies of the template on the 3' end of a primer following a s ... | 2011 | 22101935 |
| cryoelectron tomography of radial spokes in cilia and flagella. | radial spokes (rss) are ubiquitous components in the 9 + 2 axoneme thought to be mechanochemical transducers involved in local control of dynein-driven microtubule sliding. they are composed of >23 polypeptides, whose interactions and placement must be deciphered to understand rs function. in this paper, we show the detailed three-dimensional (3d) structure of rs in situ in chlamydomonas reinhardtii flagella and tetrahymena thermophila cilia that we obtained using cryoelectron tomography (cryo-e ... | 2011 | 22065640 |
| crystal structure of the eukaryotic 60s ribosomal subunit in complex with initiation factor 6. | protein synthesis in all organisms is catalyzed by ribosomes. in comparison to their prokaryotic counterparts, eukaryotic ribosomes are considerably larger and are subject to more complex regulation. the large ribosomal subunit (60s) catalyzes peptide bond formation and contains the nascent polypeptide exit tunnel. we present the structure of the 60s ribosomal subunit from tetrahymena thermophila in complex with eukaryotic initiation factor 6 (eif6), cocrystallized with the antibiotic cyclohexim ... | 2011 | 22052974 |
| several rnase t2 enzymes function in induced trna and rrna turnover in the ciliate tetrahymena. | 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 tetrahymena thermophila. we constructed strains lacking individual or combinations of these rnt2 genes that were viable but had distinct cellular and molecular phenotypes. in strains lacking only one rnt2 ... | 2012 | 22049026 |
| zygotic expression of the double-stranded rna binding motif protein drb2p is required for dna elimination in the ciliate tetrahymena thermophila. | double-stranded rna binding motif (dsrm)-containing proteins play many roles in the regulation of gene transcription and translation, including some with tandem dsrms that act in small rna biogenesis. we report the characterization of the genes for double-stranded rna binding proteins 1 and 2 (drb1 and drb2), two genes encoding nuclear proteins with tandem dsrms in the ciliate tetrahymena thermophila. both proteins are expressed throughout growth and development but exhibit distinct peaks of exp ... | 2011 | 22021239 |
| [function comparison and evolution analysis of metallothionein gene mtt2 and mtt4 in tetrahymena thermophila]. | tetrahymena has a high genetic polymorphism of metallothionein proteins. these protein isoforms can be divided into subfamilies 7a and 7b. we used real-time quantitative pcr to test the expression levels of tetrahymena thermophila metallothionein genes mtt2 and mtt4 after exposure to different inducers, including hg, cu, cd, zn and h(2)o(2). both genes were most efficiently induced by cu and secondly by hg. their expression was slightly up-regulated after exposure to cd and zn, but down-regulate ... | 2011 | 22006798 |
| experimental identification and analysis of macronuclear non-coding rnas from the ciliate tetrahymena thermophila. | 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 expressed during vegetative growth or sexual reorganization. in order to get an overview of medium-sized (40-500 nt) rnas expressed from the tetrahymena genome, we created a size-fractionated cdna librar ... | 2012 | 21967850 |
| sirtuin-mediated nuclear differentiation and programmed degradation in tetrahymena. | the nad(+)-dependent histone deacetylases, known as "sirtuins", participate in a variety of processes critical for single- and multi-cellular life. recent studies have elucidated the importance of sirtuin activity in development, aging, and disease; yet, underlying mechanistic pathways are not well understood. specific sirtuins influence chromatin structure and gene expression, but differences in their pathways as they relate to distinct chromatin functions are just beginning to emerge. to furth ... | 2011 | 21933443 |
| the pot1a-associated proteins tpt1 and pat1 coordinate telomere protection and length regulation in tetrahymena. | we have identified two new telomere proteins, tpt1 and pat1, from the ciliate tetrahymena thermophila. although tetrahymena telomerase is well characterized, only one telomere protein had previously been identified. this was the g-overhang binding-protein pot1a. tpt1 and pat1 were isolated as pot1a binding partners and shown to localize to telomeres. as tpt1 and pat1 were both found to be essential, conditional cell lines were generated to explore their function. tpt1 depletion caused a rapid gr ... | 2011 | 21900503 |
| toxicogenomic investigation of tetrahymena thermophila exposed to dichlorodiphenyltrichloroethane (ddt), tributyltin (tbt), and 2,3,7,8-tetrachlorodibenzo-p-dioxin (tcdd). | dichlorodiphenyltrichloroethane (ddt), tributyltin (tbt), and 2,3,7,8-tetrachlorodibenzo-p-dioxin (tcdd) are persistent in the environment and cause continuous toxic effects in humans and aquatic life. tetrahymena thermophila has the potential for use as a model for research regarding toxicants. in this study, this organism was used to analyze a genome-wide microarray generated from cells exposed to ddt, tbt and tcdd. to accomplish this, genes differentially expressed when treated with each toxi ... | 2011 | 21748585 |
| detection of fused genes in eukaryotic genomes using gene defuser: analysis of the tetrahymena thermophila genome. | fused genes are important sources of data for studies of evolution and protein function. to date no service has been made available online to aid in the large-scale identification of fused genes in sequenced genomes. we have developed a program, gene defuser, that analyzes uploaded protein sequence files for characteristics of gene fusion events and presents the results in a convenient web interface. | 2011 | 21745395 |
| sex ratio evolution under probabilistic sex determination. | sex allocation theory has been remarkably successful at explaining the prevalence of even sex ratios in natural populations and at identifying specific conditions that can result in biased sex ratios. much of this theory focuses on parental sex determination (sd) strategies. here, we consider instead the evolutionary causes and consequences of mixed offspring sd strategies, in which the genotype of an individual determines not its sex, but the probability of developing one of multiple sexes. we ... | 2011 | 21729059 |
| amitotic division of the macronucleus in tetrahymena thermophila: dna distribution by genomic unit. | the macronucleus of the ciliate tetrahymena cell contains euchromatin and numerous heterochromatins called chromatin bodies. during cell division, a chromatin aggregate larger than chromatin body appears in the macronucleus. we observed chromatin aggregates in the dividing macronucleus in a living t. thermophila cell, and found that these were globular in morphology and homogeneous in size. to observe globular chromatin clearly, optimal conditions for making it compact were studied. addition of ... | 2011 | 21728796 |
| exposure to cuo nanoparticles changes the fatty acid composition of protozoa tetrahymena thermophila. | in the current study, the toxicity mechanism of nanosized cuo (ncuo) to the freshwater ciliated protozoa tetrahymena thermophila was studied. changes in fatty acid profile, lipid peroxidation metabolites and reactive oxygen species (ros) were measured. bulk cuo and cuso(4) served as controls for size and solubility and 3,5-dichorophenol (3,5-dcp) as a control for a chemical known to directly affect the membrane composition. exposure to all copper compounds induced the generation of ros, whereas ... | 2011 | 21710986 |
| [expression analysis of 5 hsp70 genes in tetrahymena thermophila]. | thirteen hsp70 genes with complete conserved domains were identified in tetrahymena thermophila, and expression of five similar and non-intron hsp70 genes were analyzed. under heat shock conditions of 37, 39 and 41oc, hsp70-2 mrna had the highest relative expression level, suggesting it is closely related to heat shock. the basal level of constitutive t. thermophila hsp70-4 gene was high during 20 physiological/developmental stages of growth, starvation and conjugation, and it changed little upo ... | 2011 | 21698792 |
| inactivation of a macronuclear intra-s-phase checkpoint in tetrahymena thermophila with caffeine affects the integrity of the micronuclear genome. | aphidicolin (aph), an inhibitor of dna polymerase α, arrested cell divisions in tetrahymena thermophila. surprisingly, low concentrations of aph induced an increase of macronuclear dna content and cell size in non-dividing cells. in spite of the cell size increase, most proliferation of basal bodies, ciliogenesis and development of new oral primordia were prevented by the aph treatment. the division arrest induced by aph was partly overridden by caffeine (caf) treatment, which caused the fragmen ... | 2011 | 21601521 |
| myth4, independent of its companion ferm domain, affects the organization of an intramacronuclear microtubule array and is involved in elongation of the macronucleus in tetrahymena thermophila. | myo1 is a class xiv tetrahymena myosin involved in amitotic elongation and constriction of the macronucleus into two subnuclei at cell division. elongation of the macronucleus is accompanied by elongation of an intramacronuclear microtubule array, which is oriented parallel to the axis of nuclear elongation. elongation of the macronucleus often fails to occur or is only partially completed in a myo1 knockout, and division of the macronucleus is frequently uncoupled from cytokinesis. myo1 contain ... | 2011 | 21387572 |
| gravity-dependent changes in bioconvection of tetrahymena and chlamydomonas during parabolic flight: increases in wave number induced by pre- and post-parabola hypergravity. | 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 d ... | 2011 | 21385062 |
| whole-cell biosensors for detection of heavy metal ions in environmental samples based on metallothionein promoters from tetrahymena thermophila. | heavy metals are among the most serious pollutants, and thus there is a need to develop sensitive and rapid biomonitoring methods for heavy metals in the environment. critical parameters such as bioavailability, toxicity and genotoxicity cannot be tested using chemical analysis, but only can be assayed using living cells. a whole-cell biosensor uses the whole cell as a single reporter incorporating both bioreceptor and transducer elements. in the present paper, we report results with two gene co ... | 2011 | 21366892 |
| lanthanum(iii) impacts on metallothionein mtt1 and mtt2 from tetrahymena thermophila. | metallothionein mtt1 and mtt2 from tetrahymena thermophila are sulfydryl-rich proteins that can bind to and are inducible by heavy metals such as mercury, cadmium, zinc, and copper. however, little is known about the induction and binding of t. thermophila metallothionein by trivalent metals. in this study, we found that 10-80 μm la(3+) can promote tetrahymena cells proliferation, and fluorescence spectrum analysis showed that la(3+) can enter t. thermophila cells. real-time quantitative polymer ... | 2011 | 21359533 |
| functional comparison of metallothioneins mtt1 and mtt2 from tetrahymena thermophila. | metallothioneins mtt1 and mtt2 from tetrahymena thermophila have been characterized. the mtt1 contains mainly characteristic cys-cys-cys and cys-cys clusters, but mtt2 contains mainly cys-x-cys cluster. cd(16)-mtt1 mainly consists of α-helix and β-turns, in contrast, cd(11)-mtt2 mainly consists of random coils. reaction of cd(16)-mtt1 and cd(11)-mtt2 with nitric oxide leads to intramolecular disulfide bond formation, respectively. binding stabilities of cd(2+), hg(2+) and zn(2+) to mtt1 are stro ... | 2011 | 21352798 |
| unique sequences and predicted functions of myosins in tetrahymena thermophila. | myosins are eukaryotic actin-dependent molecular motors that play important roles in many cellular events. the function of each myosin is determined by a variety of functional domains in its tail region. in some major model organisms, the functions and properties of myosins have been investigated based on their amino acid sequences. however, in protists, myosins have been little studied beyond the level of genome sequences. we therefore investigated the mrna expression levels and amino acid sequ ... | 2011 | 21338663 |
| amitosis requires γ-tubulin-mediated microtubule assembly in tetrahymena thermophila. | to reveal the molecular systems involved in the division of a cell and its contents during cell proliferation is one of the major subjects in cell biology. although cytoskeletal organization during mitosis has been well studied, consensus on the molecular basis of amitosis has not been achieved. here we adapted an immunofluorescence method and investigated the cellular localization of γ-tubulin and microtubules (mts) in dividing tetrahymena. although the macronucleus (mac) lacks a bipolar spindl ... | 2011 | 21246753 |
| crystal structure of the eukaryotic 40s ribosomal subunit in complex with initiation factor 1. | eukaryotic ribosomes are substantially larger and more complex than their bacterial counterparts. although their core function is conserved, bacterial and eukaryotic protein synthesis differ considerably at the level of initiation. the eukaryotic small ribosomal subunit (40s) plays a central role in this process; it binds initiation factors that facilitate scanning of messenger rnas and initiation of protein synthesis. we have determined the crystal structure of the tetrahymena thermophila 40s r ... | 2011 | 21205638 |
| chemoattraction to lysophosphatidic acid does not require a change in membrane potential in tetrahymena thermophila. | lpa (lysophosphatidic acid), a known chemoattractant for many types of eukaryotic cells, is also a reliable chemoattractant for tetrahymena. since lpa receptors are gpcrs (g-protein coupled receptors) in many cell types and several putative gpcr sequences can be found in the tetrahymena genome database, we are interested to determine whether similar gpcr pathways can be used for chemosensory transduction in tetrahymena. to confirm our procedures, we tested the known chemoattractant proteose pept ... | 2011 | 21091443 |
| a sequence-dependent exonuclease activity from tetrahymena thermophila. | telomere function requires a highly conserved g rich 3'- overhang. this structure is formed by 5'-resection of the c-rich telomere strand. however, while many nucleases have been suggested to play a role in processing, it is not yet clear which nucleases carry out this 5'-resection. | 2010 | 21080963 |
| comprehensive analysis reveals dynamic and evolutionary plasticity of rab gtpases and membrane traffic in tetrahymena thermophila. | cellular sophistication is not exclusive to multicellular organisms, and unicellular eukaryotes can resemble differentiated animal cells in their complex network of membrane-bound structures. these comparisons can be illuminated by genome-wide surveys of key gene families. we report a systematic analysis of rabs in a complex unicellular ciliate, including gene prediction and phylogenetic clustering, expression profiling based on public data, and green fluorescent protein (gfp) tagging. rabs are ... | 2010 | 20976245 |
| hydrolysis of 2-arachidonoylglycerol in tetrahymena thermophila. identification and partial characterization of a monoacylglycerol lipase-like enzyme. | tetrahymena thermophila is a model organism for molecular and cellular biology. previous studies from our group showed that tetrahymena contains major components of the endocannabinoid system, such as various endocannabinoids and faah. in mammalian cells the endocannabinoid 2-arachidonoylglycerol is inactivated mainly by magl. in this study we showed that 2-arachidonoylglycerol and 2-oleoylglycerol are hydrolyzed by the combined actions of magl and faah. magl-like activity was examined in the pr ... | 2010 | 20889319 |
| electron tomography and immuno-labeling of tetrahymena thermophila basal bodies. | basal bodies and centrioles are highly ordered, microtubule-based organelles involved in the organization of the mitotic spindle and the formation of cilia and flagella. the ciliate tetrahymena thermophila has more than 700 basal bodies per cell, making it an excellent choice for the study of the structure, function, and assembly of basal bodies. here, we describe methods for cryofixation of tetrahymena by high-pressure freezing and freeze-substitution (hpf/fs) for the analysis of basal body str ... | 2010 | 20869521 |
| establishment of a cre/loxp recombination system for n-terminal epitope tagging of genes in tetrahymena. | 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. | 2010 | 20626890 |
| microcalorimetric investigation of the toxic action of berberine on tetrahymena thermophila bf(5). | tetrahymena thermophila (t. thermophila) bf(5) produces heat through growth and metabolism. by microcalorimetry, the power-time curves of the metabolism of t. thermophila bf(5) at 28 °c were measured and some quantitative parameters were obtained from these curves. then the action of berberine on this microbe was investigated. furthermore, the minimum inhibitory concentration (mic) of berberine against t. thermophila bf(5) growth was obtained by tube dilution method. berberine of different conce ... | 2010 | 20586071 |
| [toxicity of leachate of different landfill ages and different seasons]. | leachates from 7 landfill of wuhan, china were selected to determine the toxicity of leachates of different landfill age and different seasons, and relationships between physical-chemical parameters and toxicity of leachates were also study. bioassays were conducted recording toxicity against tetrahymena thermophila as median lethal concentrations (lc50 values) after 24h exposure and growth inhibition. the results show that lc50 values of leachates of different landfill age oscillate between 0.8 ... | 2010 | 20391730 |
| a domesticated piggybac transposase plays key roles in heterochromatin dynamics and dna cleavage during programmed dna deletion in tetrahymena thermophila. | transposons comprise large fractions of eukaryotic genomes and provide genetic reservoirs for the evolution of new cellular functions. we identified tpb2, a homolog of the piggybac transposase gene that is required for programmed dna deletion in tetrahymena. tpb2 was expressed exclusively during the time of dna excision, and its encoded protein tpb2p was localized in dna elimination heterochromatin structures. notably, silencing of tpb2 by rnai disrupts the final assembly of these heterochromati ... | 2010 | 20357003 |
| a ferm domain in a class xiv myosin interacts with actin and tubulin and localizes to the cytoskeleton, phagosomes, and nucleus in tetrahymena thermophila. | previous studies have shown that myo1(myosin class xiv) localizes to the cytoskeleton and is involved in amitosis of the macronucleus and trafficking of phagosomes. myo1 contains a ferm domain that could be a site for interaction between myo1 and the cytoskeleton. here, we explore the function of ferm by investigating its cytoskeleton binding partners and involvement in localization of myo1. alignment of myo1 ferm with a talin actin-binding sequence, a map-2 tubulin-binding sequence, the radixin ... | 2010 | 20169533 |
| mass spectrometry imaging of mating tetrahymena show that changes in cell morphology regulate lipid domain formation. | mass spectrometry imaging has been used here to suggest that changes in membrane structure drive lipid domain formation in mating single-cell organisms. chemical studies of lipid bilayers in both living and model systems have revealed that chemical composition is coupled to localized membrane structure. however, it is not clear if the lipids that compose the membrane actively modify membrane structure or if structural changes cause heterogeneity in the surface chemistry of the lipid bilayer. we ... | 2010 | 20133641 |
| ciliate telomerase rna loop iv nucleotides promote hierarchical rnp assembly and holoenzyme stability. | telomerase adds simple-sequence repeats to chromosome 3' ends to compensate for the loss of repeats with each round of genome replication. to accomplish this de novo dna synthesis, telomerase uses a template within its integral rna component. in addition to providing the template, the telomerase rna subunit (ter) also harbors nontemplate motifs that contribute to the specialized telomerase catalytic cycle of reiterative repeat synthesis. most nontemplate ter motifs function through linkage with ... | 2010 | 20106956 |
| identification of endocannabinoids and related n-acylethanolamines in tetrahymena. a new class of compounds for tetrahymena. | the endocannabinoid system is a lipid signaling system in mammalian cells. we reported that major components of the endocannabinoid system such as fatty acid amide hydrolase and monoacylglycerol lipase, are present in the protist tetrahymena, with characteristics similar to those in mammals. tetrahymena is a model organism for molecular and cellular biology studies as its genome sequence is available. here we report the presence of n-acylethanolamines (aces) and their respective 2-acylglycerols ... | 2010 | 20096629 |
| an rpa-related sequence-specific dna-binding subunit of telomerase holoenzyme is required for elongation processivity and telomere maintenance. | telomerase ribonucleoprotein complexes copy an internal rna template to synthesize dna repeats. dna-interacting subunits other than telomerase reverse transcriptase (tert) and telomerase rna (ter) have been hypothesized to account for high repeat addition processivity of telomerase holoenzyme compared to the minimal catalytic rnp. here, we present the identification of three additional subunits of tetrahymena thermophila telomerase holoenzyme. each of seven telomerase proteins is required for te ... | 2009 | 19941821 |
| kin-based recognition and social aggregation in a ciliate. | aggregative groups entail costs that must be overcome for the evolution of complex social interactions. understanding the mechanisms that allow aggregations to form and restrict costs of cheating can provide a resolution to the instability of social evolution. aggregation in tetrahymena thermophila is associated with costs of reduced growth and benefits of improved survival through "growth factor" exchange. we investigated what mechanisms contribute to stable cooperative aggregation in the face ... | 2010 | 19930455 |
| equilibrium properties and force-driven unfolding pathways of rna molecules. | the mechanical unfolding of a simple rna hairpin and of a 236-base portion of the tetrahymena thermophila ribozyme is studied by means of an ising-like model. phase diagrams and free energy landscapes are computed exactly and suggest a simple two-state behavior for the hairpin and the presence of intermediate states for the ribozyme. nonequilibrium simulations give the possible unfolding pathways for the ribozyme, and the dominant pathway corresponds to the experimentally observed one. | 2009 | 19905835 |
| cooperative social clusters are not destroyed by dispersal in a ciliate. | 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. | 2009 | 19828046 |
| histone h2b ubiquitylation is not required for histone h3 methylation at lysine 4 in tetrahymena. | ubiquitylation of histone h2b and/or a component of the system that ubiquitylates h2b is required for methylation of histone h3 at lysine 4 (h3k4) in yeasts and probably in humans. in this study, the single ubiquitylation site was mapped to conserved lysine 115 of the c-terminal region of histone h2b in the single-cell model organism tetrahymena thermophila. in strains lacking h2b ubiquitylation, h3k4 methylation was not detectably affected. as in other organisms, the e2 ubiquitin-conjugating en ... | 2009 | 19822522 |
| effects of artemisinin derivative on the growth metabolism of tetrahymena thermophila bf5 based on expression of thermokinetics. | the toxic effects of artesunate and dihydroartemisinin on the growth metabolism of tetrahymena thermophila bf5 were studied by microcalorimetry. the results showed that: (1) low concentrations of artesunate (<or=1 mg l(-1)) and dihydroartemisinin (<or= 2 mg l(-1)) promoted the growth metabolism of t. thermophila bf5, whereas high concentrations of artesunate (1-60 mg l(-1)) and dihydroartemisinin (2-60 mg l(-1)) inhibited its growth; (2) the half inhibition concentrations ic(50) of artesunate an ... | 2010 | 19806328 |
| usual and unusual biochemical properties of adf/cofilin-like protein adf73p in ciliate tetrahymena thermophila. | 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 p ... | 2009 | 19769938 |
| analysis of properties of cilia using tetrahymena thermophila. | cilia and eukaryotic flagella are important structures required for the motility of cells, the movement of medium across the surfaces of cells, and the connections between the receptor and synthetic portions of sensory cells. the axoneme forms the cytoskeleton of the cilium comprising several hundreds of proteins that assemble into the 9 + 2 arrangement of outer doublet and central pair microtubules, the inner and outer rows of dynein arms, and many other structures. tetrahymena thermophila is a ... | 2009 | 19768437 |
| high pressure freezing, electron microscopy, and immuno-electron microscopy of tetrahymena thermophila basal bodies. | preservation of tetrahymena thermophila basal body ultrastructure for visualization by transmission electron microscopy is improved by a combination of high pressure freezing (hpf) and freeze substitution (fs). these methods also reliably retain the antigenicity of cellular proteins for immuno-electron microscopy, which enables the precise localization of green fluorescent protein (gfp)-tagged and native basal body proteins. the plastic-embedded samples generated by these methods take full advan ... | 2009 | 19768433 |
| independent transport and sorting of functionally distinct protein families in tetrahymena thermophila dense core secretory granules. | dense core granules (dcgs) in tetrahymena thermophila contain two protein classes. proteins in the first class, called granule lattice (grl), coassemble to form a crystalline lattice within the granule lumen. lattice expansion acts as a propulsive mechanism during dcg release, and grl proteins are essential for efficient exocytosis. the second protein class, defined by a c-terminal beta/gamma-crystallin domain, is poorly understood. here, we have analyzed the function and sorting of grt1p (granu ... | 2009 | 19684282 |
| sequence, biogenesis, and function of diverse small rna classes bound to the piwi family proteins of tetrahymena thermophila. | paz/piwi domain (ppd) proteins carrying small rnas (srnas) function in gene and genome regulation. the ciliate tetrahymena thermophila encodes numerous ppd proteins exclusively of the piwi clade. we show that the three tetrahymena piwi family proteins (twis) preferentially expressed in growing cells differ in their genetic essentiality and subcellular localization. affinity purification of all eight distinct twi proteins revealed unique properties of their bound srnas. deep sequencing of twi-bou ... | 2009 | 19656801 |
| toxicity of zno and cuo nanoparticles to ciliated protozoa tetrahymena thermophila. | the toxic effects of nanoparticles (nps) of zno and cuo to particle-ingesting model organism protozoa tetrahymena thermophila were evaluated. nano-zno was remarkably more toxic than nano-cuo (ec(50) values approximately 5mg metal/l versus 128mg metal/l). toxic effect of cuo depended on particle size: nano-cuo was about 10-20 times more toxic than bulk cuo. however, when calculated on basis of bioavailable copper (quantified using recombinant cu-sensor bacteria) the 4-h ec(50) values of nano- and ... | 2010 | 19622384 |
| varied truncation and clustering characterize some short repeats identified in micronucleus-specific dna of tetrahymena thermophila. | there are over 6000 internally eliminated dna sequences (iess) in the tetrahymena genome that are deleted in a programmed fashion during the development of a polyploid, somatic macronucleus from a diploid germline micronucleus. recently, based on several results, a homology and small rna-based mechanism has been proposed for the efficient elimination of ies elements. since the rnai machinery is proposed to be intimately involved in silencing potentially harmful repeats such as transposons and vi ... | 2009 | 19619624 |
| two gw repeat proteins interact with tetrahymena thermophila argonaute and promote genome rearrangement. | in conjugating tetrahymena thermophila, massive dna elimination occurs upon the development of the new somatic genome from the germ line genome. small, approximately 28-nucleotide scan rnas (scnrnas) and twi1p, an argonaute family member, mediate h3k27me3 and h3k9me3 histone h3 modifications, which lead to heterochromatin formation and the excision of the heterochromatinized germ line-limited sequences. in our search for new factors involved in developmental dna rearrangement, we identified two ... | 2009 | 19596782 |
| dyf-1 is required for assembly of the axoneme in tetrahymena thermophila. | in most cilia, the axoneme can be subdivided into three segments: proximal (the transition zone), middle (with outer doublet microtubules), and distal (with singlet extensions of outer doublet microtubules). how the functionally distinct segments of the axoneme are assembled and maintained is not well understood. dyf-1 is a highly conserved ciliary protein containing tetratricopeptide repeats. in caenorhabditis elegans, dyf-1 is specifically needed for assembly of the distal segment (g. ou, o. e ... | 2009 | 19581442 |
| dynein-2 and ciliogenesis in tetrahymena. | dynein-2 is the motor responsible for retrograde intraflagellar transport. in situ, dynein-2 comprises four subunits: the dynein-2 heavy chain (dyh2); the dynein-2 intermediate chain; the dynein-2 light-intermediate chain (d2lic); and dynein light chain 8 (rompolas et al. 2007. chlamydomonas fap133 is a dynein intermediate chain associated with the retrograde intraflagellar transport motor. j cell sci 120:3653-3665). in contrast to what has been reported in other model organisms, when the dyh2 g ... | 2009 | 19562737 |
| reconstructing three-dimensional shape envelopes from time-resolved small-angle x-ray scattering data. | modern computing power has made it possible to reconstruct low-resolution, three-dimensional shapes from solution small-angle x-ray scattering (saxs) data on biomolecules without a priori knowledge of the structure. in conjunction with rapid mixing techniques, saxs has been applied to time resolve conformational changes accompanying important biological processes, such as biomolecular folding. in response to the widespread interest in saxs reconstructions, their value in conjunction with such ti ... | 2008 | 19529835 |
| c-5(6) sterol desaturase from tetrahymena thermophila: gene identification and knockout, sequence analysis, and comparison to other c-5(6) sterol desaturases. | the gene coding for a c-5(6) sterol desaturase in tetrahymena thermophila, des5a, has been identified by the knockout of the ttherm_01194720 sequence. macronucleus transformation was achieved by biolistic bombardment and gene replacement through phenotypic assortment, using paromomycin as the selective agent. a knockout cell line (ko270) showed a phenotype consistent with that of the des5a deletion mutant. ko270 converted only 6% of the added sterol into the c-5 unsaturated derivative, while the ... | 2009 | 19525418 |
| a single rna-dependent rna polymerase assembles with mutually exclusive nucleotidyl transferase subunits to direct different pathways of small rna biogenesis. | members of the conserved family of eukaryotic rna-dependent rna polymerases (rdrs) synthesize double-stranded rna (dsrna) intermediates in diverse pathways of small rna (srna) biogenesis and rna-mediated silencing. rdr-dependent pathways of srna production are poorly characterized relative to rdr-independent pathways, and the rdr enzymes themselves are poorly characterized relative to their viral rna-dependent rna polymerase counterparts. we previously described a physical and functional couplin ... | 2009 | 19451546 |
| impact of fluorotelomer alcohols (ftoh) on the molecular and macroscopic phenotype of tetrahymena thermophila. | as possible precursors of pfoa, fluorotelomer alcohols are a class of highly fluorinated and volatile compounds. although they are widespread in the environment, little toxicity data is available. the present study focused on testing the population growth impairment potential of ftoh. moreover, certain efforts were made to find the possible effect mechanism of these compounds. | 2010 | 19333639 |
| kin5 knockdown in tetrahymena thermophila using rnai blocks cargo transport of gef1. | a critical process that builds and maintains the eukaryotic cilium is intraflagellar transport (ift). this process utilizes members of the kinesin-2 superfamily to transport cargo into the cilium (anterograde transport) and a dynein motor for the retrograde traffic. using a novel rnai knockdown method, we have analyzed the function of the homodimeric ift kinesin-2, kin5, in tetrahymena ciliary transport. in rnai transformants, kin5 was severely downregulated and disappeared from the cilia, but c ... | 2009 | 19290045 |
| nested genes cda12 and cda13 encode proteins associated with membrane trafficking in the ciliate tetrahymena thermophila. | we describe a novel pair of nested genes, cda12 and cda13, from tetrahymena thermophila. both are implicated in membrane trafficking associated with cell division and conjugation. green fluorescent protein localization reveals cda12p decoration of diverse membrane-bound compartments, including mobile, subcortical tubulovesicular compartments; perinuclear vesicles; and candidates for recycling endosomes. cda13p decorates intracellular foci located adjacent to cortically aligned mitochondria and t ... | 2009 | 19286988 |
| action of palmatine on tetrahymena thermophila bf5 growth investigated by microcalorimetry. | using a thermal activity monitor (tam) air isothermal microcalorimeter with ampoule mode, the thermo-genic curves of the metabolism of tetrahymena thermophila bf(5) growth at 28 degrees c were obtained and the action of palmatine on it was investigated. meanwhile, the biomass change during the process of t. thermophila bf(5) growth coexisted with palmatine was studied by a haemacytometer. the results showed that a low concentration (50 microg/ml) of palmatine began to inhibit the growth of t. th ... | 2009 | 19286310 |
| 2'-o-methylation stabilizes piwi-associated small rnas and ensures dna elimination in tetrahymena. | small rnas approximately 20-30 nucleotides (nt) in length regulate gene expression at the transcriptional and post-transcriptional levels. in the plant arabidopsis, all small rnas are 3'-terminal 2'-o-methylated by hen1, whereas only a subset of small rnas carry this modification in metazoans. this methylation is known to stabilize small rnas, but its biological significance remains unclear. in the ciliated protozoan tetrahymena thermophila, two classes of small rnas have been identified: rnas a ... | 2009 | 19240163 |
| palindromic gene amplification--an evolutionarily conserved role for dna inverted repeats in the genome. | the clinical importance of gene amplification in the diagnosis and treatment of cancer has been widely recognized, as it is often evident in advanced stages of diseases. however, our knowledge of the underlying mechanisms is still limited. gene amplification is an essential process in several organisms including the ciliate tetrahymena thermophila, in which the initiating mechanism has been well characterized. lessons from such simple eukaryotes may provide useful information regarding how gene ... | 2009 | 19212324 |
| the two sas-6 homologs in tetrahymena thermophila have distinct functions in basal body assembly. | cilia and flagella are structurally and functionally conserved organelles present in basal as well as higher eukaryotes. the assembly of cilia requires a microtubule based scaffold called a basal body. the ninefold symmetry characteristic of basal bodies and the structurally similar centriole is organized around a hub and spoke structure termed the cartwheel. to date, sas-6 is one of the two clearly conserved components of the cartwheel. in some organisms, overexpression of sas-6 causes the form ... | 2009 | 19158390 |
| differential targeting of tetrahymena orc to ribosomal dna and non-rdna replication origins. | the tetrahymena thermophila origin recognition complex (orc) contains an integral rna subunit, 26t rna, which confers specificity to the amplified ribosomal dna (rdna) origin by base pairing with an essential cis-acting replication determinant--the type i element. using a plasmid maintenance assay, we identified a 6.7 kb non-rdna fragment containing two closely associated replicators, ars1-a (0.8 kb) and ars1-b (1.2 kb). both replicators lack type i elements and hence complementarity to 26t rna, ... | 2009 | 19153611 |
| manipulating ciliary protein-encoding genes in tetrahymena thermophila. | tetrahymena thermophila has emerged as an excellent protist model for studies on cilia that are based on reverse genetic approaches. in tetrahymena, genes can be routinely disrupted by the dna homologous recombination. we present established protocols for the manipulation of genes in either the germline micronucleus or the somatic macronucleus. a detailed protocol is provided for the construction of heterokaryon strains that carry a gene disruption only in the micronucleus. heterokaryon strain c ... | 2009 | 20409809 |
| identification and characterization of dynein genes in tetrahymena. | we describe the protocol through which we identify and characterize dynein subunit genes in the ciliated protozoan tetrahymena thermophila. the gene(s) of interest is found by searching the tetrahymena genome, and it is characterized in silico including the prediction of the open reading frame and identification of likely introns. the gene is then characterized experimentally, including the confirmation of the exon-intron organization of the gene and the measurement of the expression of the gene ... | 2009 | 20409796 |
| basal body components exhibit differential protein dynamics during nascent basal body assembly. | basal bodies organize cilia that are responsible for both mechanical beating and sensation. nascent basal body assembly follows a series of well characterized morphological events; however, the proteins and their assembly dynamics for new basal body formation and function are not well understood. high-resolution light and electron microscopy studies were performed in tetrahymena thermophila to determine how proteins assemble into the structure. we identify unique dynamics at basal bodies for eac ... | 2009 | 19056680 |
| refined annotation and assembly of the tetrahymena thermophila genome sequence through est analysis, comparative genomic hybridization, and targeted gap closure. | tetrahymena thermophila, a widely studied model for cellular and molecular biology, is a binucleated single-celled organism with a germline micronucleus (mic) and somatic macronucleus (mac). the recent draft mac genome assembly revealed low sequence repetitiveness, a result of the epigenetic removal of invasive dna elements found only in the mic genome. such low repetitiveness makes complete closure of the mac genome a feasible goal, which to achieve would require standard closure methods as wel ... | 2008 | 19036158 |
| my01, a class xiv myosin, affects developmentally-regulated elimination of the macronucleus during conjugation of tetrahymena thermophila. | nuclear dimorphism is characteristic of ciliated protozoa. a transcriptionally-active macronucleus co-exists with a transcriptionally-silent micronucleus, which is activated only at conjugation. during conjugation, each conjugant develops two new genetically matched macronuclei and micronuclei, and the pre-existing macronucleus is eliminated. elimination of the pre-existing macronucleus during conjugation is an apoptotic-like process. the macronucleus becomes highly condensed, dna laddering occu ... | 2009 | 19032155 |
| high efficiency transformation of tetrahymena using a codon-optimized neomycin resistance gene. | tetrahymena thermophila is a useful model for the study of eukaryotic biology. a neomycin resistance gene (neo) has been developed that was optimized for the codon usage of t. thermophila. using this codon-optimized neo gene (neotet), a new drug resistance marker cassette, neo4, has been constructed. the neo4 cassette resulted in about ten times more drug resistant transformants than a cassette containing the non-codon-optimized original neo gene. the new cassette enables transgenic tetrahymena ... | 2008 | 18775482 |
| dynamic nuclear reorganization during genome remodeling of tetrahymena. | the single-celled ciliate tetrahymena thermophila possesses two versions of its genome, one germline, one somatic, contained within functionally distinct nuclei (called the micronucleus and macronucleus, respectively). these two genomes differentiate from identical zygotic copies. the development of the somatic nucleus involves large-scale dna rearrangements that eliminate 15 to 20 mbp of their germline-derived dna. the genomic regions excised are dispersed throughout the genome and are largely ... | 2008 | 18706458 |
| evolutionary origins and functions of the carotenoid biosynthetic pathway in marine diatoms. | 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-bas ... | 2008 | 18682837 |