| sequence of the small subunit ribosomal rna gene from the hypotrichous ciliate euplotes aediculatus. | we have determined the complete nucleotide sequence of the coding region of the small subunit rrna gene of the hypotrichous ciliate euplotes aediculatus. it is 1882 nucleotides long and contains several inserts not present in the small subunit rrna genes of the hypotrichs oxytricha nova and stylonychia pustulata. a comparison of the sequences suggests that e. aediculatus is much less closely related to these other two hypotrichs than they are to each other. although the gene sequence of e. aedic ... | 1986 | 3007752 |
| morphology and development of the macronuclei of the ciliates stylonychia mytilus and euplotes aediculatus. | | 1971 | 4996055 |
| all gene-sized dna molecules in four species of hypotrichs have the same terminal sequence and an unusual 3' terminus. | in hypotrichous ciliates, all of the macronuclear dna is in the form of low molecular weight molecules with an average size of approximately 2200 base pairs. total macronuclear dna from four hypotrichs has been shown to have inverted terminal repeats by direct sequence analysis. in oxytricha nova, oxytricha sp., and stylonychia pustulata, this terminal sequence may be written as 5'-c4a4c4a4c4 ... 3'-g4t4g4t4g4t4g4t4g4 ... in euplotes aediculatus, the sequences is similar but differs in the lengt ... | 1981 | 6265931 |
| the organization of macronuclear rdna molecules of four hypotrichous ciliated protozoans. | we have compared the structure of macronuclear dna molecules that contain rrna genes of four hypotricous ciliates, stylonychia pustulata, euplotes aediculatus, oxytricha fallax and oxytricha nova. the macronuclear rdna, like all macronuclear dna in hypotrichs, exists as achromosomal molecules of approximately single-gene size. the rdna molecules have been cloned intact as recombinant plasmids and analyzed by restriction mapping and southern hybridization. the sites of restriction enzymes bamhi, ... | 1982 | 6284451 |
| gene-sized dna molecules of the macronuclei in three species of hypotrichs: size distributions and absence of nicks. dna of ciliated protozoa. viii. | macronuclear dna s from three related hypotrichous ciliated protozoans were compared by agarose gel electrophoresis. each was shown to be composed of dna duplexes that yielded a unique pattern of bands overlying a continuous distribution of dna sizes ranging from approximately 400 bp to approximately 20,000 bp. by em, the number average molecular sizes for double-stranded dna were 2,200 bp for oxytricha sp., 2,514 bp for stylonychia pustulata and 18,836 bp for euplotes aediculatus. contrary to p ... | 1980 | 6771110 |
| nuclear roles in the postconjugant development of the ciliated protozoan euplotes aediculatus. 1. evidence for sequential roles of the differentiating macronucleus in exconjugant development. | | 1981 | 6786939 |
| isolation of omikron-endosymbionts from mass cultures of euplotes aediculatus and characterization of their dna. | | 1982 | 7117400 |
| telomerase rnas of different ciliates have a common secondary structure and a permuted template. | telomerase is composed of protein and rna. the rna serves as a template for telomere dna synthesis and may also be important for enzyme structure or catalysis. we have used the presence of conserved sequence elements in the promoter and template regions to amplify by pcr the telomerase rna genes from six different hypotrichous ciliates: oxytricha nova, oxytricha trifallax, stylonychia mytilis, stylonychia lemnae, euplotes aediculatus, and euplotes eurystomus. rnaseh cleavage of the o. nova rna i ... | 1994 | 7958872 |
| polynucleobacter necessarius, an obligate bacterial endosymbiont of the hypotrichous ciliate euplotes aediculatus, is a member of the beta-subclass of proteobacteria. | an almost full length 16s rrna gene of the obligate bacterial endosymbiont polynucleobacter necessarius was amplified using the polymerase chain reaction in combination with site-specific primers. the amplified dna was directly sequenced and compared with other bacterial 16s rrna sequences. p. necessarius belongs to the beta-subclass of proteobacteria and shows the closest relationship to alcaligenes eutrophus, burkholderia solanacearum, and b. pickettii. in proteobacteria and shows the closest ... | 1996 | 8595875 |
| purification of telomerase from euplotes aediculatus: requirement of a primer 3' overhang. | telomerase is a ribonucleoprotein enzyme that uses its internal rna moiety as a template for synthesis of telomeric repeats at chromosome ends. here we report the purification of telomerase from euplotes aediculatus by affinity chromatography with antisense 2'-o-methyl oligonucleotides, a method that was developed for small nuclear ribonucleoprotein particles (snrnps). elution of bound ribonucleoprotein from the antisense oligonucleotide under nondenaturing conditions was achieved by a novel app ... | 1996 | 8855245 |
| the anchor site of telomerase from euplotes aediculatus revealed by photo-cross-linking to single- and double-stranded dna primers. | telomerase is a ribonucleoprotein enzyme that adds telomeric sequence repeats to the ends of linear chromosomes. in vitro, telomerase has been observed to add repeats to a dna oligonucleotide primer in a processive manner, leading to the postulation of a dna anchor site separate from the catalytic site of the enzyme. we have substituted photoreactive 5-iododeoxypyrimidines into the dna oligonucleotide primer d(t4g4t4g4t4g2) and, upon irradiation, obtained cross-links with the anchor site of telo ... | 1997 | 8972210 |
| reverse transcriptase motifs in the catalytic subunit of telomerase. | telomerase is a ribonucleoprotein enzyme essential for the replication of chromosome termini in most eukaryotes. telomerase rna components have been identified from many organisms, but no protein component has been demonstrated to catalyze telomeric dna extension. telomerase was purified from euplotes aediculatus, a ciliated protozoan, and one of its proteins was partially sequenced by nanoelectrospray tandem mass spectrometry. cloning and sequence analysis of the corresponding gene revealed tha ... | 1997 | 9110970 |
| effects of cadmium on growth and motility in euplotes aediculatus isolated from activated sludge. | | 1997 | 9115151 |
| telomerase catalytic subunit homologs from fission yeast and human. | catalytic protein subunits of telomerase from the ciliate euplotes aediculatus and the yeast saccharomyces cerevisiae contain reverse transcriptase motifs. here the homologous genes from the fission yeast schizosaccharomyces pombe and human are identified. disruption of the s. pombe gene resulted in telomere shortening and senescence, and expression of mrna from the human gene correlated with telomerase activity in cell lines. sequence comparisons placed the telomerase proteins in the reverse tr ... | 1997 | 9252327 |
| dgtp-dependent processivity and possible template switching of euplotes telomerase. | we have measured the processivity of telomeric dna extension by euplotes aediculatus telomerase at various concentrations of the nucleotide substrates dgtp and dttp. the maximum processivity (approximately 3 repeats) was observed at approximately 100 microm of each dntp. processivity decreased as the dntp concentrations were reduced and, surprisingly, as the concentration of dgtp was increased. also, the characteristic banding pattern generated by telomerase extension of dna primers shifted in r ... | 1997 | 9278493 |
| isolation of a candidate human telomerase catalytic subunit gene, which reveals complex splicing patterns in different cell types. | telomerase is a multicomponent reverse transcriptase enzyme that adds dna repeats to the ends of chromosomes using its rna component as a template for synthesis. telomerase activity is detected in the germline as well as the majority of tumors and immortal cell lines, and at low levels in several types of normal cells. we have cloned a human gene homologous to a protein from saccharomyces cerevisiae and euplotes aediculatus that has reverse transcriptase motifs and is thought to be the catalytic ... | 1997 | 9328464 |
| human telomerase contains evolutionarily conserved catalytic and structural subunits. | we have cloned and characterized a human gene encoding tp2 (telomerase-associated protein 2), a protein with similarity to reverse transcriptases and the catalytic telomerase subunits from saccharomyces cerevisiae and euplotes aediculatus. indirect immunofluorescence revealed that tp2 was localized to the nucleus. using antibodies to endogenous and epitope-tagged tp2, we found that tp2 was associated specifically with human telomerase activity and the recently identified telomerase-associated pr ... | 1997 | 9389643 |
| reconstitution of human telomerase with the template rna component htr and the catalytic protein subunit htrt. | the maintenance of chromosome termini, or telomeres, requires the action of the enzyme telomerase, as conventional dna polymerases cannot fully replicate the ends of linear molecules. telomerase is expressed and telomere length is maintained in human germ cells and the great majority of primary human tumours. however, telomerase is not detectable in most normal somatic cells; this corresponds to the gradual telomere loss observed with each cell division. it has been proposed that telomere erosio ... | 1997 | 9398860 |
| telomerase is a true reverse transcriptase. a review. | synthesis of telomeric repeats at chromosome ends requires telomerase, a ribonucleoprotein enzyme. the rna subunit, which contains the template for dna synthesis, has been identified in many organisms. recently, the protein subunit that catalyzes telomeric dna extension has also been identified in euplotes aediculatus and saccharomyces cerevisiae. it has sequence and functional characteristics of a reverse transcriptase related to retrotransposon and retroviral reverse transcriptases, so this ne ... | 1997 | 9467843 |
| telomerase and the chromosome end replication problem. | telomerase, the enzyme that extends chromosomal dna ends in most eukaryotes, contains essential rna and protein subunits. we have been studying telomere replication in hypotrichous ciliates such as euplotes aediculatus, which have numerous short macronuclear dna molecules and therefore are highly enriched in telomeres and in telomerase. cloning and sequencing genes for the rna subunits from several ciliates revealed that telomerase rnas with insignificant nucleotide sequence homology nevertheles ... | 1997 | 9524749 |
| euplotes telomerase: evidence for limited base-pairing during primer elongation and dgtp as an effector of translocation. | the telomeric sequence repeats at the ends of eukaryotic chromosomes are maintained by the ribonucleoprotein enzyme telomerase. telomeric dna primers are bound by telomerase both at the active site, which includes base-pairing with the rna template, and at a second anchor site. the stabilities of euplotes aediculatus primer-telomerase complexes were determined by measuring their dissociation rates (koff), using an assay involving photo-cross-linking at the anchor site. the primer length was vari ... | 1998 | 9548747 |
| new insights into the phylogeny of eukaryotes based on ciliate hsp70 sequences. | the current framework of the eukaryotic phylogeny is based on the analysis of a comprehensive set of sequences of the small subunit ribosomal rna. however, phylogenies based on protein-encoding genes are not completely congruent with this picture. since congruence between different markers is the best tool to determine evolutionary history, we focused on hsp70 (heat-shock protein of 70 kda), a chaperone protein which is highly conserved and is a potentially reliable phylogenetic marker. we used ... | 1998 | 9718722 |
| evolution of the eukaryotic translation termination system: origins of release factors. | accurate translation termination is essential for cell viability. in eukaryotes, this process is strictly maintained by two proteins, eukaryotic release factor 1 (erf1), which recognizes all stop codons and hydrolyzes peptidyl-trna, and eukaryotic release factor 3 (erf3), which is an elongation factor 1alpha (ef-1alpha) homolog stimulating erf1 activity. to retrace the evolution of this core system, we cloned and sequenced the erf3 genes from trichomonas vaginalis (parabasalia) and giardia lambl ... | 2000 | 10833194 |
| euplotes telomerase contains an la motif protein produced by apparent translational frameshifting. | telomerase is the ribonucleoprotein enzyme responsible for the replication of chromosome ends in most eukaryotes. in the ciliate euplotes aediculatus, the protein p43 biochemically co-purifies with active telomerase and appears to be stoichiometric with both the rna and the catalytic protein subunit of this telomerase complex. here we describe cloning of the gene for p43 and present evidence that it is an authentic component of the telomerase holoenzyme. comparison of the nucleotide sequence of ... | 2000 | 11080168 |
| class i release factors in ciliates with variant genetic codes. | in eukaryotes with the universal genetic code a single class i release factor (erf1) most probably recognizes all stop codons (uaa, uag and uga) and is essential for termination of nascent peptide synthesis. it is well established that stop codons have been reassigned to amino acid codons at least three times among ciliates. the codon specificities of ciliate erf1s must have been modified to accommodate the variant codes. in this study we have amplified, cloned and sequenced erf1 genes of two hy ... | 2001 | 11160924 |
| stop codon recognition in ciliates: euplotes release factor does not respond to reassigned uga codon. | in eukaryotes, the polypeptide release factor 1 (erf1) is involved in translation termination at all three stop codons. however, the mechanism for decoding stop codons remains unknown. a direct interaction of erf1 with the stop codons has been postulated. recent studies focus on erf1 from ciliates in which some stop codons are reassigned to sense codons. using an in vitro assay based on mammalian ribosomes, we show that erf1 from the ciliate euplotes aediculatus responds to uaa and uag as stop c ... | 2001 | 11463747 |
| effects of nucleotide analogues on euplotes aediculatus telomerase processivity: evidence for product-assisted translocation. | telomerase is a unique ribonucleoprotein that reverse transcribes a defined region of its rna subunit onto the ends of eukaryotic chromosomes. the product of telomerase, telomeric dna, is typically a g-rich repeated sequence, (ttttgggg)(n) in the ciliate euplotes aediculatus and (ttaggg)(n) in humans. telomerase can extend oligonucleotide primers in vitro in a processive fashion. we used dntp analogues to study the structure-activity relationship between substrate nucleotides and processivity of ... | 2002 | 11772012 |
| ca2+-dependent contractility of isolated and demembranated macronuclei in the hypotrichous ciliate euplotes aediculatus. | the hypotrichous ciliated protozoan euplotes aediculatus possesses a characteristic c-shaped somatic nucleus (macronucleus) within the cytoplasm, which shows dynamic shape change during the cell cycle. it is shown that isolated macronuclei possess ca(2+)-dependent contractility. macronuclei were isolated, stuck fast on the glass surface, and subjected to different concentrations of ca(2+) in a ca(2+)-egta buffer. the nuclei became expanded at [ca(2+)]<10(-7)m, and they contracted on subsequent a ... | 2003 | 12531187 |
| occurrence of articulins and epiplasmins in protists. | the cortex of ciliates. dinoflagellates, and euglenoids comprises a unique structure called the epiplasm, implicated in pattern-forming processes of the cell cortex and in maintaining cell shape. articulins, a novel class of cytoskeletal proteins, are major constituents of the epiplasm in the flagellate euglena gracilis and the ciliate pseudomicrothorax dubius. the hallmark of articulins is a core domain of repetitive motifs of alternating valine and proline residues, the vpv-motif. the vpv-moti ... | 2003 | 12674475 |
| plateins: a novel family of signal peptide-containing articulins in euplotid ciliates. | in euplotid ciliates, the cortex is reinforced by alveolar plates--proteinaceous scales located within the membranous alveolar sacs, forming a monolayer just below the plasma membrane. this system appears to play a cytoskeletal role analogous to that provided by the fibrous epiplasm found beneath the cortical alveoli in other ciliates. in euplotes aediculatus, the major alveolar plate proteins (termed alpha-, beta-, and gamma-plateins) have been identified. using anti-platein antibodies, an expr ... | 2003 | 12674476 |
| the euplotes la motif protein p43 has properties of a telomerase-specific subunit. | telomerase is a specialized reverse transcriptase synthesizing dna repeats at telomeres. in addition to the rna and catalytic protein components, telomerase from the ciliate euplotes aediculatus contains the subunit p43. this protein is homologous to the la autoantigen, functioning in maturation of rna polymerase iii transcripts. here we provide evidence that p43 is primarily associated with the telomerase ribonucleoprotein in vivo. recombinant p43 binds telomerase rna with low-nanomolar affinit ... | 2003 | 12741831 |
| myb genes in ciliates: a common origin with the myb protooncogene? | in animals, the protooncogene myb family is characterized by a dna-binding domain (so-called myb domain), which consists of 3 imperfect tandem repeats of a helix-turn-helix motif. homologous genes have been characterized in plants and also in dictyostelium discoideum. however, in plants, the myb family is more diverse and displays 2 types of myb domains: the animal-like 3 repeats (myb-3r) and the 2 repeats (myb-2r) domains. the question is therefore raised as to the putative existence of genes w ... | 2003 | 13677450 |
| predator diet breadth influences the relative importance of bottom-up and top-down control of prey biomass and diversity. | we investigated the effects of predator diet breadth on the relative importance of bottom-up and top-down control of prey assemblages, using microbial food webs containing bacteria, bacterivorous protists and rotifers, and two different top predators. the experiment used a factorial design that independently manipulated productivity and the presence or absence of two top predators with different diet breadths. predators included a "specialist" predatory ciliate euplotes aediculatus, which was re ... | 2005 | 15729665 |
| acute toxicity of heavy metals towards freshwater ciliated protists. | the acute toxicity of five heavy metals to four species of freshwater ciliates (colpidium colpoda, dexiotricha granulosa, euplotes aediculatus, and halteria grandinella) was examined in laboratory tests. after exposing the ciliates to soluble compound of cadmium, copper, chromium, lead, and nickel at several selected concentrations, the mortality rate was registered and the lc50 values (with 95% confidence intervals) were calculated. large differences appeared in sensitivities of the four specie ... | 2006 | 16198032 |
| electron microscopic visualization of telomerase from euplotes aediculatus bound to a model telomere dna. | binding of the telomerase ribonucleoprotein from the ciliate euplotes aediculatus to telomeric dna in vitro has been examined by electron microscopy (em). visualization of the structures that formed revealed a globular protein complex that localized to the dna end containing the e. aediculatus telomere consensus 3'-single-strand t(4)g(4)t(4)g(4)t(4)g(2) overhang. gel filtration confirmed that purified e. aediculatus telomerase is an active dimer in solution, and comparison of the size of the dna ... | 2006 | 16878997 |
| [how translation termination factor erf1 euplotes does not recognise uga stop codon]. | in universal-code eukaryotes, a single class-1 translation termination factor erf1 decodes all three stop codons, uaa, uag, and uga. in some ciliates with variant genetic codes one or two stop codons are used to encode amino acid(s) and are not recognized by erf1. in stylonychia, uag and uaa codons are reassigned as glutamine codons, and in euplotes, uga is reassigned as cysteine codon. in omnipotent erf1s, stop codon recognition is associated with the n-terminal domain of erf1. because variant- ... | 2007 | 18318120 |
| emended description of the genus polynucleobacter and the species polynucleobacter necessarius and proposal of two subspecies, p. necessarius subsp. necessarius subsp. nov. and p. necessarius subsp. asymbioticus subsp. nov. | heckmann and schmidt described the genus polynucleobacter for bacterial endosymbionts of freshwater ciliates affiliated with the genus euplotes, and the species polynucleobacter necessarius for obligate endosymbionts living in the cytoplasm of euplotes aediculatus. pure cultures of the type strain could not be established due to the obligate nature of the symbiotic relationship between the endosymbionts and their hosts. therefore, polynucleobacter necessarius is one of a few bacterial species wi ... | 2009 | 19567561 |
| toxoplasma gondii: further studies on the subpellicular network. | the association of the pellicle with cytoskeletal elements in toxoplasma gondii allows this parasite to maintain its mechanical integrity and makes possible its gliding motility and cell invasion. the inner membrane complex (imc) resembles the flattened membrane sacs observed in free-living protozoa and these sacs have been found to associate with cytoskeletal proteins such as articulins. we used immunofluorescence microscopy to characterise the presence and distribution of plateins, a sub-famil ... | 2009 | 19820829 |
| a single amino acid change of translation termination factor erf1 switches between bipotent and omnipotent stop-codon specificity. | in eukaryotes a single class-1 translation termination factor erf1 decodes the three stop codons: uaa, uag and uga. some ciliates, like euplotes, have a variant code, and here erf1s exhibit uar-only specificity, whereas uga is reassigned as a sense codon. since eukaryote erf1 stop-codon recognition is associated with its n-terminal domain, structural features should exist in the n domain of ciliate erf1s that restrict their stop-codon specificity. using an in vitro reconstituted eukaryotic trans ... | 2011 | 20860996 |