Publications
| Title | Abstract | Year Filter | PMID(sorted ascending) Filter |
|---|
| mistranslation in a eucaryotic organism. | previous work from our laboratory has demonstrated that a subclass of the aminoglycoside antibiotics, those containing the drug fragment paromamine, stimulates mistranslation in cell-free protein-synthesizing systems derived from eucaryotic cells. we report here experiments which show that the ciliate tetrahymena thermophila (formerly t. pyriformis, syngen 1) is sensitive to the paromamine-containing aminoglycoside antibiotics. the drugs are active with respect to growth inhibition, inhibition o ... | 1978 | 75070 |
| transformation in tetrahymena thermophila. development of an inducible phenotype. | 1978 | 109331 | |
| use of 8-hydroxyquinoline to enrich for temperature-sensitive mutants of tetrahymena. | the effects of the chelating agent 8-hydroxyquinoline (hq) on tetrahymena thermophila were examined. cell division was completely inhibited by 5 micrograms of hq per ml. at this concentration deoxyribonucleic acid, ribonucleic acid, and protein syntheses were also completely and nonselectively inhibited. the inhibition was reversible after 6 h of hq treatment. at concentrations above 20 micrograms/ml a 10,000-fold decrease in survival as seen after 2 h in the drug. the sensitivity of tetrahymena ... | 2000 | 110771 |
| dual capacity for nutrient uptake in tetrahymena. v. utilization of amino acids and proteins. | we investigated the relative contributions of phagocytosis and plasma membrane transport to the uptake of amino acids and a protein (egg albumin) in amounts which allow tetrahymena thermophila to grow and multiply. we used a mutant capable of indefinite growth without food vacuole formation (phagocytosis) and its wild type (phagocytosis-competent) isogenic parental strain. our results suggest that phagocytosis is not required for free amino acid uptake, most or all of which can be attributed to ... | 2000 | 110820 |
| induced resistance to 6-methylpurine and cycloheximide in tetrahymena. ii. variation within vegetative cultures of micronucleate t. thermophila and amicronucleate t. pyriformis. | resistance to 6-methylpurine and cycloheximide has been induced in both the micronucleate species tetrahymena thermophila and the amincronucleate species t. pyriformis. resistance follows only after mutagen treatment and vegetative growth. the frequencies with which resistant variants are induced and the independence of mutagenesis and selection are demonstrated. all evidence is consistent with the hypothesis that macronuclear subunits are assorting in both species during vegetative growth to pr ... | 2002 | 150921 |
| direction of active sliding of microtubules in tetrahymena cilia. | axonemes of protozoan (tetrahymena thermophila biii) cilia, isolated by the dibucaine method, were treated briefly with trypsin after removal of the ciliary membranes by treatment with triton x-100. after attachment to polylysine-coated surfaces, the partially digested axonemes remained mainly intact cylinders. such attached axonemes can be treated with atp, which induces microtubles sliding. atp-treated preparations showed disrupted axonemes in which doublets had telescoped out of the original ... | 1988 | 266725 |
| cycloheximide resistance can be mediated through either ribosomal subunit. | two cycloheximide-resistant mutants of tetrahymena thermophila were analyzed to determine the site of their cycloheximide resistance. the mutations in both strains had been previously shown to be genetically dominant and located at separate loci (denoted chx-a and chx-b). strains carrying these mutations were readily distinguished by the extent to which they were resistant to the drug. the homozygous double mutant was more resistant than either single mutant. cell-free extracts of wild type and ... | 1962 | 277918 |
| micronuclei of tetrahymena contain two types of histone h3. | evidence is presented that micronuclei of tetrahymena thermophila contain significant amounts of two types of histone h3. one is indistinguishable from that found in macronuclei and the other is unique to micronuclei. the micronucleus-specific h3 has a slightly faster mobility than the common h3 in three different gel systems (both of these species were artifactually lost during procedures for histone preparation in previous studies). both micronuclear h3s appear to contain a single cysteine res ... | 1979 | 291904 |
| localization of transcribed regions on extrachromosomal ribosomal rna genes of tetrahymena thermophila by r-loop mapping. | r-loop hybridization and electron microscopy were used to map the rna transcription products of the extrachromosomal rrna genes of tetrahymena thermophila. the mature 17s and 26s rrnas and the nuclear 35s pre-rrna and pre-26s rrna were located with a precision of approximately 100 base pairs. a 370-base pair intervening sequence was found in the 26s coding region. it has the same size and relative location as that found in tetrahymena pigmentosa [wild, m.a. & gall, j.g. (1979) cell 16, 565-573]. ... | 1979 | 291921 |
| mutants of tetrahymena thermophila with temperature sensitive food vacuole formation. ii. physiological and morphological studies. | 1979 | 315879 | |
| acid hydrolases and their release in food vacuole-less mutants of tetrahymena thermophila. | mutants (np1 and psj5) of tetrahymena thermophila strains b and d 1968 exist that are unable to construct a functional oral apparatus and form food vacuoles at 37 c but which do so normally at 30 c. food vacuole-less cells starved in dilute salt solution released similar amounts of acid phosphatase, beta-n-acetyl-glucosaminidase and alpha-glucosidase activity into the medium as wildtype cells during an 8-h period. actively growing, food vacuole-less cells had approximately 50% less total protein ... | 1979 | 395296 |
| a mutant of tetrahymena thermophila with a partial mirror-image duplication of cell surface pattern. i. analysis of the phenotype. | cells of a mutant clone, cu-127, of tetrahymena thermophila (formerly t. pyriformis, syngen 1) manifest three anatomical abnormalities. first, the stable number of ciliary meridians is 21-25, above the usual number (17-21) in this species. second, up to 30% of the cells have two oral apparatuses (oas), one normal and the other abnormal. third, more than one-half of the cells possess two distinct sets of contractile vacuole pores (cvps). in some living cells two contractile vacuoles are seen. the ... | 1979 | 448267 |
| a mutant of tetrahymena thermophila with a partial mirror-image duplication of cell surface pattern. ii. nature of genic control. | the cu-127 clone of tetrahymena thermophila, which manifests an unusually high number of ciliary rows plus a second set of abnormal oral structures and of contractile vacuole pores with partial mirror-image reversal of asymmetry (jerka-dziadosz & frankel, 1979), has been subjected to breeding analysis. the progeny ratios obtained in various crosses indicate that the abnormalities of cell-surface asymmetry are brought to expression as a result of the action of a recessive allele at a single gene ... | 1979 | 448269 |
| peptidase activity in tetrahymena. | this report strongly suggests that two compartments in tetrahymena thermophila contain peptidase activity: the cytoplasm and the outer cell surface. determinations of amino acid concentrations in the extracellular medium upon incubation of cells with peptides suggest that the surface-bound peptidase activity hydrolyses di- and tri-phenylalanine equally fast on a molar basis. growth experiments designed to characterize the in vivo peptidase specificities showed that both t. thermophila and t. pyr ... | 1979 | 489666 |
| the functional units of macronuclear assortment in tetrahymena thermophila. | 1979 | 510922 | |
| variability in the timing and outcome of macronuclear assortment in tetrahymena thermophila. | 1979 | 510923 | |
| ribosome biosynthesis in tetrahymena thermophila. iii. regulation of ribosomal rna degradation in growing and growth arrested cells. | we have measured the turnover rate of ribosomal rna in exponentially growing tetrahymena thermophila cells, cells entering the plateau phase of growth, and nutrient-deprived (starved) cells. ribosomal rna is stable in cells in early log phase growth but it begins to turnover as the cells begin a deceleratory growth phase prior to entering a plateau state. likewise, rrna in cells transferred from early log phase growth to a starvation medium begins to be degraded immediately upon starvation. in b ... | 1979 | 511957 |
| an enrichment for temperature-sensitive mutants in tetrahymena thermophila. | the parameters for the killing of tetrahymena by 5-bromodeoxyuridine(budr) and near-ultraviolet light have been determined. significant preferential killing by uv of cells that have incorporated budr was obtained when the cells were irradiated in a nonnutrient buffer. uv alone was found to be toxic to cells irradiated in growth medium. mutants defective in division at a restrictive temperature were isolated from mutagenized cultures that had been treated with budr and uv and from mutagenized cul ... | 1979 | 520821 |
| germinal aging in tetrahymena thermophila. | the manifestations of germinal aging in the ciliate tetrahymena thermophila include death of the cells at conjugation and macronuclear retention in which the normal replacement of the old macronucleus by a new one fails to occur. available data suggest that methods of routine maintenance that reduce the number of fissions may delay aging. differences in breeding performance following maintenance for 1-5 years in axenic peptone broth vs. bacterized cerophyl were not significant; those following m ... | 1979 | 522511 |
| ribosome biosynthesis in tetrahymena thermophila. iv. regulation of ribosomal rna synthesis in growing and growth arrested cells. | three parameters involved in the production of new ribosomal rna (rrna) were measured in tetrahymena thermophilia: (i) the rate of synthesis of the rrna precursor, (ii) the rate of processing of the rna precursor and rrna intermediates and (iii) the efficiency of utilization of the rrna precursor in producing mature ribosomal rna. these parameters were measured in cells in exponential growth and in cells starved in a dilute salt solution. growing cells synthesize rrna 20 times faster and process ... | 1979 | 528575 |
| mitochondrial associations with specific microtubular components of the cortex of tetrahymena thermophila. i. cortical patterning of mitochondria. | many of the mitochondria of tetrahymena thermophila are localized in the cell cortex in regular, identifiable patterns. two different mitochondrial patterns are seen; whether a cell expresses one or the other type apparently depends upon nutrient conditions in the culture and not upon other factors tested. consistent associations between cortical mitochondria and certain of the cortical microtubular bands are seen at the light-microscopic level. electron-microscopic observations confirm this and ... | 1979 | 528586 |
| mass selection of conditional mating mutants of tetrahymena thermophila. | the mating reaction in tetrahymena thermophila includes a starvation period and two distinct cell interactions, co-stimulation and cell pairing, before the cells are cytoplasmically joined as conjugants. a selection procedure for harvesting mutants unable to mate at a restrictive temperature has been developed. a conjugant pair consisting of one cycloheximide-resistant cell and one wild-type cell (cycloheximide-sensitive) was itself sensitive to the drug. by adding cycloheximide and nutrient med ... | 1979 | 528976 |
| an analysis of spindle ultrastructure during prometaphase and metaphase of micronuclear division in tetrahymena. | mitotic micronuclei were isolated from tetrahymena thermophila in a medium containing hexylene glycol and their ultrastructure was analyzed using thin section techniques. the two stages selected for analysis were early prometaphase and metaphase. a comparison of data from these two stages revealed several differences in nuclear morphology. metaphase nuclei were longer, they contained more microtubules, and the distribution of microtubules at metaphase was different from that at early prometaphas ... | 1979 | 535497 |
| the regulation of amounts and proportions of genetic elements in the macronuclei of tetrahymena thermophila strains of diverse karyotype. | measurements of the micronuclear dna content of clones with assumed different degrees of micronuclear ploidy confirmed the triploid nature of one clone. the micronuclear dna content of a presumptive haploid clone was found to be slightly higher than expected, whereas one of two aneuploid clones had an unexpectedly low micronuclear dna content. the macronuclear dna content of cells with macronuclei which had developed from triploid, diploid and probably haploid and aneuploid macronuclear-anlagen ... | 1979 | 536381 |
| perturbance analysis of nuclear determination in tetrahymena i: background, rationale, and illustrative example, employing temperature responses. | a model based on comparative considerations, is presented for the nuclear determination of mating type in tetrahymena thermophila. the model proposes a system of three binary control elements, each capable of stable persistence in one of two states. a general method is proposed for evaluating the model and for assigning particular mating types to particular compound states. preliminary assignments of mating types are made from the responses of nuclei to temperature differentials. | 1977 | 590659 |
| induced resistance to 6-methylpurine and cycloheximide in tetrahymena. i. germ line mutants of t. thermophila. | two new mutant lines of tetrahymena thermophila (t. pyriformis, syngen 1), each conferring resistance to a different agent, are described. resistance to cycloheximide and 6-methylpurine are each determined by dominant genes, chxa2 and mpr; the traits show phenotypic assortment. the method used to select these mutations, the critical importance of backcrossing to wild type following mutagenesis, and the utility of these marker genes in further mutagenic selection schemes and studies of the sexual ... | 1978 | 689366 |
| induced resistance to 6-methylpurine and cycloheximide in tetrahymena. ii. variation within vegetative cultures of micronucleate t. thermophila and amicronucleate t. pyriformis. | resistance to 6-methylpurine and cycloheximide has been induced in both the micronucleate species tetrahymena thermophila and the amicronucleate species t. pyriformis. resistance follows only after mutagen treatment and vegetative growth. the frequencies with which resistant variants are induced and the independence of mutagenesis and selection are demonstrated. all evidence is consistent with the hypothesis that macronuclear subunits are assorting in both species during vegetative growth to pro ... | 1978 | 689367 |
| the dna replication schedule is not affected in a division blocked mutant of tetrahymena thermophila. | 1978 | 720404 | |
| directionality of microtubule assembly: an in vivo study with the ciliate tetrahymena. | a temperature-sensitive mutant homozygous for the recessive gene molb in tetrahymena thermophila offers opportunity for studying the direction of microtubule assembly in vivo. at 39 degrees c the mutant fails to divide properly; the 2 daughter animals remain attached and bend over each other. as revealed by protargol staining, the bending results in acute turning and breaking of some of the longitudinal microtubular bands close and parallel to the surface. hence, 2 broken microtubular ends are a ... | 1978 | 721903 |
| histone-histone interactions in a lower eukaryote, tetrahymena thermophila. | the six pairwise interactions of tetrahymena macronuclear histones h2a (formerly hx), h2b, h3, and h4 have been studied using the techniques of circular dichroism and continuous variation. parallel experiments have been performed with calf thymus histones as controls, and the 12 possible interspecies pairs have also been examined. the behavior of three of the ciliate histones, h2a, h2b, and h3 is virtually identical with that of their vertebrate counterparts. tetrahymena h4 exhibits a pattern of ... | 1978 | 728429 |
| life cycle variation and regulation of macronuclear dna content in tetrahymena thermophila. | the mean dna content of g2 macronuclei varies during the life cycle of the ciliate tetrahymena thermophila. early in the life cycle the mean is about 130 c; later it is about 94 c. in hybrids between strains a and b the decrease from 130 c to 94 c usually began after 60 fissions after conjugation. in b x b clones the decrease was complete by 50 fissions. the data suggest that there may be a genetic difference between strains a and b with respect to the onset of the decrease in dna content. the d ... | 1978 | 738160 |
| nuclear divisions with reduced numbers of microtubules in tetrahymena. | ultrastructural observations on micronuclei of tetrahymena thermophila, wh-6 dividing in the presence of colchicine suggest that the microtubules present at the time of drug addition persist, but no new microtubules are formed. it is suggested that the great amount of elongation seen in these drug-treated micronuclei may not be due to the persisting microtubules alone. on the basis of ultrastructural and light-microscopic observations, it is proposed that at least part of the motive force respon ... | 1978 | 748345 |
| the pre-pairing events in tetrahymena thermophila. analysis of blocks imposed by high concentrations of tris-cl. | 1979 | 761602 | |
| traumatic induction of early maturity in tetrahymena. | exposure of conjugating pairs of tetrahymena thermophila to high temperature (37 degrees) during macronuclear development causes an abortion of many macronuclei, but it also often induces an early appearance of sexual maturity in clones completing macronuclear development. lines become mature after about 15 cell divisions rather than after 50 or more cell divisions in untreated pairs. the phenotype resembles that associated with em (early maturity) mutants but, because it is not transmitted to t ... | 1977 | 885337 |
| a micronucleus-limited sequence family in tetrahymena thermophila: organization and sequence conservation. | during macronuclear development in the ciliated protozoan tetrahymena thermophila, sequence reorganization including sequence loss occurs. addressing questions about the organization and nucleotide sequence of micronucleus limited regions can lead to insights about mechanisms of dna rearrangements during macronuclear development as well as mechanisms for the maintenance of the stability of micronucleus-limited sequence families. we have previously identified a moderately repetitive micronucleus- ... | 1992 | 1327599 |
| calmodulin cdnas from two species of tetrahymena. | we describe the isolation and characterization of cdnas encoding calmodulins of tetrahymena thermophila and tetrahymena pyriformis. it reveals that the deduced amino acid sequences of both calmodulins are precisely the same. | 1992 | 1339295 |
| drugs affecting microtubule dynamics increase alpha-tubulin mrna accumulation via transcription in tetrahymena thermophila. | in cultured mammalian cells, an increase in the amount of tubulin monomer due to treatment with a microtubule-depolymerizing agent results in a rapid decline in tubulin synthesis. this autoregulatory response is mediated through a posttranscriptional mechanism which decreases the stability of tubulin message with no change in transcriptional activity of tubulin genes. conversely, treatment with a microtubule-polymerizing drug, such as taxol, results in a slight increase in the synthesis of tubul ... | 1992 | 1347905 |
| lysosomal enzymes produced by immobilized tetrahymena thermophila. | the ciliated protozoon tetrahymena thermophila was immobilized for production of secreted lysosomal enzymes in two ways. cells entrapped in solid ca-alginate spheres survived but were unable to grow and multiply. however, when encapsulated in hollow ca-alginate spheres tetrahymena multiplied well, reaching 0.9 x 10(7) cells/ml. these immobilized cells secreted large amounts of lysosomal enzymes when the medium was changed daily. this system was transferred to a reactor scale using a conical bubb ... | 1991 | 1368701 |
| isoleucyl-trna synthetase from the ciliated protozoan tetrahymena thermophila. dna sequence, gene regulation, and leucine zipper motifs. | we have determined the nucleotide sequence of a protozoan aminoacyl-trna synthetase. the isoleucyl-trna synthetase (ilers) gene [ilsa; formerly cupc, martindale, d. w., martindale, h. m., and bruns, p. j. (1986) nucleic acids res. 14, 1341-1354] from the ciliate tetrahymena thermophila was sequenced and found to have eight introns, four transcription start sites, and a putative polypeptide of 1081 amino acids. a polypeptide 20 amino acids longer could be made if a transcribed in-frame atg close ... | 1992 | 1371507 |
| in vitro transcription in isolated nucleoli of tetrahymena pyriformis. | an in vitro transcription system was established using extrachromosomal nucleoli from tetrahymena pyriformis macronuclei as a template. ribosomal precursor rna (pre-rrna) and nascent pre-rrna chains were removed from isolated nucleoli by treatment with rnase t1 and sarkosyl. nucleoli were then incubated in a rna synthetic cocktail containing a cellular extract from tetrahymena thermophila. the transcription product was examined for the presence of transcripts from t. pyriformis ribosomal dna (rd ... | 1992 | 1379895 |
| differential increase in activity of acid phosphatase induced by phosphate starvation in tetrahymena. | we have studied the effects of phosphate starvation on the levels and distributions of activities of acid phosphatase and beta-hexosaminidase in cultures of tetrahymena thermophila. the cells were grown in synthetic nutrient medium and refed every day with fresh medium. after 4 days of growth in the complete medium, the cultures were divided into two portions. one received complete medium and the other phosphate-free, but otherwise complete, medium. population densities and activities of acid ph ... | 1992 | 1386323 |
| ciliary polypeptides and glycoconjugates of wild-type and mutant tetrahymena thermophila: starved versus nonstarved. | to investigate the role of cilia in mating interactions of tetrahymena thermophila, ciliary membrane-rich fractions were isolated from two wild-type strains, a non-discharge mucocyst mutant which possesses mating behavior similar to wild-type, and a mating mutant which is able to costimulate cells of complementary mating type but cannot enter into pair formation. in each case, proteins from the ciliary membrane-rich fractions of starved, mating-competent ("initiated") cells were compared with th ... | 1992 | 1395138 |
| mapping the mating type locus of tetrahymena thermophila: meiotic linkage of mat to the ribosomal rna gene. | tetrahymena thermophila has a multiple mating type system. while a sexually mature cell usually expresses only one mating type, its germline (micronucleus) carries the genetic potential for 5 to 7 mating types. the set of allowed mating types is specified by the mat locus. the choice of which particular mating type is expressed by a cell reflects a somatically inherited, developmentally programmed differentiation of the somatic nucleus (macronucleus). in this work we report that the mat locus ma ... | 1992 | 1395139 |
| mutation affecting cell separation and macronuclear resorption during conjugation in tetrahymena thermophila: early expression of the zygotic genotype. | a new recessive conjugation lethal mutation was found in tetrahymena thermophila which was named mra for macronuclear resorption arrest. other events affected by the mra mutations are separation of pairs, dna replication in the macronuclear anlagen, and resorption of one of the two micronuclei. in wild-type crosses 50% of the pairs had separated by 12 hr after mixing two mating types and had completed resorption of the old macronucleus 1-2 hr later. in contrast most mra conjugants did not separa ... | 1992 | 1395143 |
| stochastic developmental variation in the ratio of allelic rdnas among newly differentiated, heterozygous macronuclei of tetrahymena thermophila. | ciliates possess nuclear dimorphism, i.e., they carry two structurally and functionally differentiated types of nuclei. the micronucleus and macronucleus serve as the germline and somatic nuclei, respectively, of the cell. the macronucleus differentiates from a mitotic sister of the micronucleus once per life cycle. macronuclear differentiation is accompanied by a developmentally programmed set of dna rearrangements, including chromosome fragmentation, telomere addition, and amplification. given ... | 1992 | 1395146 |
| the immobilization antigens of tetrahymena thermophila are glycoproteins. | the four immobilization antigens controlled by the serh locus in tetrahymena thermophila have been isolated and partially characterized (doerder, f.p. & berkowitz, m.s. 1986. purification and partial characterization of the h immobilization antigens of tetrahymena thermophila. j. protozool., 33:204-208). we show here, using immunoprecipitation and electrophoresis after labeling with 35s-methionine, 14c-mannose, 14c-glucosamine, and n-acetyl-d-[l-3h]glucosamine, that these proteins are glycosylat ... | 2008 | 1403985 |
| efficient mass transformation of tetrahymena thermophila by electroporation of conjugants. | conjugating cells of the ciliate tetrahymena thermophila were electroporated in the presence of plasmid dna containing a paromomycin-resistant ribosomal rna gene (rdna). cells were selected with paromomycin following 12-24 hr of growth on nonselective medium. resistant cells appeared after 2-3 days. processing vectors containing the micronuclear rdna and somatic vectors containing the macronuclear gene transformed the cells, with the former yielding frequencies up to 900 transformants per microg ... | 1992 | 1409625 |
| an assessment of proteolytic enzymes in tetrahymena thermophila. | cellular extracts of tetrahymena thermophila were found to contain substantial levels of proteolytic activity. protein digestion occurred over broad ranges of ph, ionic strength, and temperature and was stimulated by treatment with thiol reductants, edta and sodium dodecyl sulfate. incubation at temperatures > or = 60 degrees c or with high concentrations of chaotropic reagents such as 10 m urea or 6 m guanidine-hcl caused an apparent irreversible loss of activity. activity was also strongly dim ... | 1992 | 1453353 |
| immobilization antigens from tetrahymena thermophila are glycosyl-phosphatidylinositol-linked proteins. | we have studied four strains of tetrahymena thermophila, each of which expresses a different allele of the serh gene and produces a distinctive surface protein of the immobilization antigen (i-antigen) class. following exposure of the strains to [3h]ethanolamine or [3h]myristic acid, a protein corresponding in molecular mass to the characteristic i-antigen for that strain became highly labeled, as determined by mobility in sodium dodecylsulfate-polyacrylamide electrophoresis gels. furthermore, a ... | 1987 | 1453361 |
| dynamics of ribozyme binding of substrate revealed by fluorescence-detected stopped-flow methods. | fluorescence-detected stopped-flow and equilibrium methods have been used to study the mechanism for binding of pyrene (pyr)-labeled rna oligomer substrates to the ribozyme (catalytic rna) from tetrahymena thermophila. the fluorescence of these substrates increases up to 25-fold on binding to the ribozyme. stopped-flow experiments provide evidence that pyr experiences at least three different microenvironments during the binding process. a minimal mechanism is presented in which substrate initia ... | 1992 | 1455230 |
| chromatin structure and conserved sequence elements in genes encoding ribosomal proteins in tetrahymena thermophila. | the chromatin structure of the macronuclear genes encoding ribosomal proteins s25 and l1 in the ciliated protozoan tetrahymena thermophila was analyzed. using the indirect end-labelling technique, dnase-i-hypersensitive regions were located in the promoter regions as well as in the 3' regions of the genes. the dnase-i-hypersensitive regions were present in chromatin of exponentially growing cells, where the rate of ribosomal-protein gene transcription is high, and in chromatin from starved cells ... | 1992 | 1459144 |
| uniparental cytogamy: a novel method for bringing micronuclear mutations of tetrahymena into homozygous macronuclear expression with precocious sexual maturity. | a new method of inducing self-fertilization, uniparental cytogamy, yields homozygous germinal and somatic genotypes in the ciliate tetrahymena thermophila. progeny are highly fertile and show a marked tendency for precocious sexual maturity. this method is highly effective in protocols designed to generate and express nonlethal dominant or recessive mutations. | 1992 | 1459424 |
| analysis of the role of phosphate oxygens in the group i intron from tetrahymena. | we have developed a quantitative substitution interference technique to examine the role of pro-rp oxygens in the phosphodiester backbone of rna, using phosphorothioates as a structural probe. this approach is generally applicable to any reaction involving rna in which the precursor and reaction products can be separated. we have applied the technique to identity structural requirements in the group i intron from tetrahymena thermophila for catalysis of hydrolysis at the 3' splice site; 44 phosp ... | 1992 | 1469712 |
| tetrahymena gene encodes a protein that is homologous with the liver-specific f-antigen and associated with membranes of the golgi apparatus and transport vesicles. | the f-antigen is a prominent liver protein which has been extensively used in studies on natural and induced immunological tolerance. however, its intracellular localization and biological function have remained elusive. it has generally been assumed that the f-antigen is confined phylogenetically to vertebrates. now we have cloned and characterized a gene from the ciliated protozoan tetrahymena thermophila encoding a protein which clearly is homologous with the rat f-antigen. the coding region ... | 1992 | 1469718 |
| chemotactic properties, cellular binding and uptake of peptides and peptide derivatives: studies with tetrahymena thermophila. | receptor-mediated binding of leukocyte chemotactic peptide, n-formylmet-leu-phe (fmlp), occurs in the ciliated protozoon tetrahymena thermophila. in vivo labelling of the cells with n-formylmet-leu-[3h]phe ([3h]fmlp) shows that the cells bind the ligand with high affinity (kd = 4 x 10(-9) m to 1 x 10(-8) m). moreover, scatchard transformations of the binding data show that there are about 5 x 10(5) binding sites per cell on the cell surface. two fluorescent derivatives of leukocyte chemotactic p ... | 1992 | 1478955 |
| replication-dependent and independent regulation of hmg expression during the cell cycle and conjugation in tetrahymena. | two abundant high-mobility-group (hmg)-like proteins, hmg b and hmg c, exist in the ciliated protozoan, tetrahymena thermophila. of these, hmg c is specific to transcriptionally active macronuclei, while hmg b is found in macronuclei and in transcriptionally inactive micronuclei [1]. using northern and in situ analyses, we show that the genes encoding hmg b and hmg c are not expressed uniformly throughout the vegetative cycle or during the sexual process, conjugation. elevated expression of both ... | 1992 | 1480473 |
| protein phosphorylation and the regulation of basal body microtubule organizing centres in tetrahymena. | previous work suggests that changes in the phosphorylation state of some centrosomal proteins regulate centrosomal activity. the hypothesis that changes in the phosphorylation state of one or more basal body microtubule organizing centre (mtoc) components regulate its ability to nucleate cilia assembly in tetrahymena thermophila was tested. the mpm-2 antibody, which recognizes phosphorylated epitopes in mtocs in a variety of organisms, was used to probe immunoblots of cytoskeletal frameworks pre ... | 1992 | 1486799 |
| cellular uptake and degradation of phosphorothioate oligonucleotides by marine and freshwater ciliates. | to date, no antisense studies have been reported with either ciliated protozoa or marine organisms. this study examines the feasibility of using antisense oligonucleotides to alter gene expression in marine and freshwater ciliates. radiolabeled, phosphorothioate-modified oligonucleotides were used to investigate whether ciliates take up and degrade oligonucleotides present in the culture medium. with all three ciliates examined, euplotes crassus, tetrahymena thermophila, and oxytricha nova, the ... | 1992 | 1490074 |
| rate of phenotypic assortment in tetrahymena thermophila. | during vegetative, asexual reproduction in heterozygous tetrahymena thermophila, the macronucleus divides amitotically to produce clonal lineages that express either one or the other allele but not both. because such phenotypic assortment has been described for every locus studied, its mechanism has important implications concerning the development and structure of the macronucleus. the primary tools to study assortment are rf, the rate at which subclones come to express a single allele stably, ... | 1992 | 1499154 |
| immunocytochemical analysis of secretion mutants of tetrahymena using a mucocyst-specific monoclonal antibody. | dense-core granules represent an adaptation of specialized secretory cells to facilitate stimulus-regulated release of stored proteins. such granules are a prominent feature of mammalian neuroendocrine and exocrine cells and are also well developed in the ciliates. in tetrahymena thermophila, the ability to generate mutants in dense-core granule biosynthesis and fusion presents a versatile system for dissecting steps in regulated exocytosis. we have previously shown that defective granules in su ... | 1992 | 1499156 |
| genetic characterization of tetrahymena thermophila mutants unable to secrete capsules. | under appropriate conditions, alcian blue-induced exocytosis of tetrahymena mucocysts leads to formation of a capsule that surrounds the cell. this phenomenon is an example of regulated secretion, a mechanism of fundamental significance in eukaryotic cells. in order to dissect genetically the mechanism of mucocyst biogenesis and regulated exocytosis, mutants unable to form capsules (caps-) were isolated. in this paper we report a genetic characterization of caps- mutants in this collection. the ... | 1992 | 1499157 |
| genetic characterization of the secretory mutant ms-1 of tetrahymena thermophila: vacuolarization and block in secretion of lysosomal hydrolases are caused by a single gene mutation. | the genetics and phenotypic features (light and electron microscopy) of a secretory mutant, ms-1 of tetrahymena thermophila blocked in secretion of lysosomal acid hydrolases have been analyzed. although blocked constitutively in secretion, ms-1 contains active lysosomal hydrolases in amounts equivalent to the wild type. the 3:1 segregation in f-2 in sib crosses and the 1:1 segregation in test crosses indicate that the block in secretion of lysosomal hydrolases is controlled by a recessive single ... | 1992 | 1499158 |
| locus-dependent profiles of the rescue of nonexcitable behavioral mutants during conjugation in tetrahymena thermophila. | the tetrahymena nonreversal (tnr) mutants of tetrahymena thermophila are behavioral mutants with nonexcitable membranes. when cells of the tnrb mutant were mated with wild type, a phenotypic change occurred about 1 h after pair formation. the pairs began to lose their heterotypic character in stimulation solution containing high potassium and, within 1 1/2 h, they were not distinguishable from the wild-type homotypic pairs. on the contrary, although pairs of the tnra and wild type also lost thei ... | 1992 | 1499159 |
| the influence of fission line expression on the number and positioning of oral primordia in the cdaa1 mutant of tetrahymena thermophila. | during cytokinesis, furrowing creates new boundaries for daughter cells. following a shift to a restrictive temperature, cells of the temperature-sensitive cell-division-arrest (cdaa1) mutant of tetrahymena thermophila complete development of the oral apparatus for the prospective posterior daughter cell before becoming arrested in cytokinesis. when maintained under weak restrictive conditions (35 degrees c), some of the chains were arrested prior to the start of fission line formation (d-shaped ... | 1992 | 1499162 |
| exceptions to mutual exclusion among cell surface i-antigens of tetrahymena thermophila during salt stress and stationary phase. | in ciliates, only one of the alternative forms of the immunodominant membrane glycoprotein usually coats the external surface of the cell. such mutual exclusion is regulated at the pretranslational level by mechanisms that result in the expression of a single protein gene. in the holotrich tetrahymena thermophila five alternative cell surface immobilization proteins (i-antigens) are expressed under different conditions of temperature (l, h, t) and culture media (i, s). using polyclonal and monoc ... | 1992 | 1522546 |
| structural organization of the genes encoding the small nuclear rnas u1 to u6 of tetrahymena thermophila is very similar to that of plant small nuclear rna genes. | we report the sequences of the genes encoding the small nuclear rnas (snrnas) u1 to u6 of the ciliate tetrahymena thermophila. the genes of the individual snrnas exist in two to six slightly different copies per haploid genome. sequence analyses of the gene-flanking regions indicate that there are two classes of snrna genes. both classes are characterized by several conserved sequence elements, some of which are unique to each class and some of which are found in both classes. comparison of the ... | 1992 | 1522583 |
| a temperature-sensitive mutation affecting synthesis of outer arm dyneins in tetrahymena thermophila. | we have characterized a novel, temperature-sensitive mutation affecting motility in tetrahymena thermophila. mutants grew and divided normally at the restrictive temperature (38 degrees c), but became nonmotile. scanning electron microscopic analysis indicated that nonmotile mutants contained the normal number of cilia and that the cilia were of normal length. transmission electron microscopic analysis indicated that axonemes isolated from nonmotile mutants lacked outer dynein arms, so the mutat ... | 2009 | 1533674 |
| characterization of dna-directed rna polymerases in isolated macronuclei of the ciliated protozoan tetrahymena thermophila. effects of purified ornithine decarboxylase and amine compounds. | the possible regulatory interactions of purified ornithine decarboxylase with dna-directed rna polymerases in isolated macronuclei from the ciliated protozoan tetrahymena thermophila were studied. it has been found that highly purified odc (specific activity 10.2 mumols co2 x h-1 x mg-1), even at activities of 37,500 nmol co2 x h-1 per ml failed to alter rna polymerase activity in the in vitro transcription assay in the presence or absence of the substrate l-ornithine at 20mm. the naturally occu ... | 1992 | 1536693 |
| genomic sequence encoding a heat shock-induced, rna polymerase iii-transcribed rna from tetrahymena thermophila. | 1992 | 1542582 | |
| characterization of a cdna clone from the haemoparasite babesia bovis encoding a protein containing an "hmg-box". | the complete nucleotide sequence of a babesia bovis cdna clone encoding a protein containing an hmg-box has been determined. the predicted protein of 97 amino acids has a molecular weight of 11,116. it exhibits approximately 45% overall amino acid identity with the saccharomyces cerevisiae non-histone protein 6a (nhp6a) and approximately 57% identity in the hmg-box. the b. bovis protein has been designated nhp1. like hnp6a, and unlike most other hmg1 homologues, nhp1 does not have a basic or an ... | 1992 | 1567437 |
| a genetic screen for vegetative gene expression in the micronucleus of tetrahymena thermophila. | the presence of a micronucleus with at least a small portion of the micronuclear genome appears to be indispensable for vegetative viability in the ciliate tetrahymena thermophila. a genetic screen was devised to detect evidence of expression of essential genes in the vegetative micronucleus by identification of thermosensitive-lethal mutations expressed in the absence of nuclear reorganization. although control experiments demonstrated the efficacy of the method for induction and recovery of th ... | 2007 | 1578407 |
| a phylogenetic analysis based on the gene encoding phosphoglycerate kinase. | we have determined the nucleotide sequence of both genomic and complementary dna (cdna) for the gene encoding the glycolytic enzyme phosphoglycerate kinase from the ciliated protozoan tetrahymena thermophila. the amino acid sequence for the enzyme has also been derived from the cdna sequence. the gene contains an open reading frame of 1260 nucleotides encoding 420 amino acids. coding sequence in genomic dna is interrupted by two introns at positions corresponding to introns 3 and 4 in mammalian ... | 1992 | 1602492 |
| tetrahydropyran ring-containing fatty acid-combined taurine (tetrathermoyltaurine) in the taurolipid fraction of tetrahymena thermophila. | a tetrahydropyran ring-containing fatty acid-combined taurine (tetrathermoyltaurine) was found in the taurolipid fraction of tetrahymena thermophila. tetrathermoyltaurine accounted for about 0.6% of the total taurolipid of the cells. the compound was subjected to methanolic hydrochloric acid hydrolysis, and the structures of the hydrolysis products were identified by nuclear magnetic resonance and mass spectrometries, as taurine and 2,3-dihydroxy-9,13-oxy-7-trans-octadecenoic acid (tetrathermic ... | 1992 | 1627630 |
| sequence of a new snrna from the ciliate tetrahymena thermophila. | 1992 | 1630929 | |
| identification of tetrahymena ciliary surface proteins labeled with sulfosuccinimidyl 6-(biotinamido) hexanoate and concanavalin a and fractionated with triton x-114. | tetrahymena thermophila cells were labeled with sulfosuccinimidyl 6-(biotinamido) hexanoate, a sensitive nonradioactive probe for cell surface proteins, and western blots of axonemes and ciliary membrane vesicles were compared to cilia fractionated with triton x-114 (tx-114) in order to study the orientation of ciliary membrane proteins. greater than 40 ciliary surface polypeptides, from greater than 350 kda to less than 20 kda, were resolved. the major surface 50-60 kda proteins are hydrophobic ... | 2015 | 1640384 |
| characterization of the t, l, i, s, m and p cell surface (immobilization) antigens of tetrahymena thermophila: molecular weights, isoforms, and cross-reactivity of antisera. | in the ciliate protist tetrahymena thermophila the l, h, t, i, s, m and p cell surface proteins (immobilization antigens) are expressed under different conditions of temperature (l, h, t), culture media (i, s), and mutant genotype (m, p). immunoblot and autoradiographic studies using antisera to purified protein show that the molecular weights of these proteins range from 25,000 to 59,000. the h, t, s, m and p antigens are recognized as single polypeptides, whereas l, i, and one allelic form of ... | 1992 | 1640388 |
| timing of the appearance of ubiquitinated histones in developing new macronuclei of tetrahymena thermophila. | vegetative cells of the ciliated protozoan tetrahymena thermophila contain a transcriptionally active macronucleus and a transcriptionally inert micronucleus. during vegetative growth, macronuclear histones h2a and h2b and micronuclear h2a are ubiquitinated. despite differences in function, macro- and micro-nuclei are related. during conjugation (the sexual phase of the life cycle in tetrahymena), postzygotic division products of micronuclei give rise to new micro- and macro-nuclei. using an ant ... | 1991 | 1645982 |
| tel-1 transposon-like elements of tetrahymena thermophila are associated with micronuclear genome rearrangements. | the micronuclear genome of tetrahymena thermophila contains tel-1 elements that structurally resemble transposons. here we present molecular evidence that tel-1 transposon-like elements are mobile. the arrangements of tel-1 elements in the micronuclear genomes of several t. thermophila strains and cell lines were assayed by southern blotting. the molecular evidence for tel-1 transposition is most striking in strains that have undergone unusual laboratory-induced meioses. the genetic history of t ... | 1991 | 1657703 |
| native yeast telomeres are sufficient to stabilize linear dna in xenopus laevis oocytes. | we have constructed a linear plasmid in yeast containing the entire bovine papillomavirus genome and tested its physical stability following microinjection into stage vi oocytes of xenopus laevis. our results show that unmodified telomeres, in contrast to the yeast-passaged telomeres, drastically affect the stability of the injected linear plasmid. plasmids carrying unmodified tetrahymena thermophila telomeric sequences are rapidly degraded in oocytes. when these plasmids are passed through yeas ... | 1991 | 1657721 |
| dna cleavage catalysed by the ribozyme from tetrahymena. | an rna enzyme derived from the self-splicing intervening sequence of tetrahymena thermophila catalyses sequence-specific cleavage of an oligodeoxyribonucleotide substrate. compared with rna, the dna substrate is bound very weakly and is cleaved very slowly, revealing the importance of the rna 2'-hydroxyl group in both the binding and chemical steps. the finding that catalysis by rna can extend to dna substrates indicates new possibilities for the transposition of intervening sequences and for th ... | 1990 | 1690858 |
| selection in vitro of an rna enzyme that specifically cleaves single-stranded dna. | the discovery of rna enzymes has, for the first time, provided a single molecule that has both genetic and catalytic properties. we have devised techniques for the mutation, selection and amplification of catalytic rna, all of which can be performed rapidly in vitro. here we describe how these techniques can be integrated and performed repeatedly within a single reaction vessel. this allows evolution experiments to be carried out in response to artificially imposed selection constraints. we work ... | 1990 | 1690861 |
| prediction of rna secondary structure, including pseudoknotting, by computer simulation. | a computer program is presented which determines the secondary structure of linear rna molecules by simulating a hypothetical process of folding. this process implies the concept of 'nucleation centres', regions in rna which locally trigger the folding. during the simulation, the rna is allowed to fold into pseudoknotted structures, unlike all other programs predicting rna secondary structure. the simulation uses published, experimentally determined free energy values for nearest neighbour base ... | 1990 | 1693421 |
| nucleotide sequence and functional characterization of a mitochondrial trna(trp) from tetrahymena thermophila. | 1991 | 1709497 | |
| three-dimensional folding of tetrahymena thermophila rrna ivs sequence: a proposal. | we studied the tetrahymena thermophila rrna ivs sequence with the aim of obtaining a model of the structure characterized by the bases proximity of the self-reactions sites. the considered sequence kept up those fragments essential for its catalytic activity as demonstrated by deletion mutants. the first step was the theoretical analysis with a computer method previously proposed, to find optimal free energy secondary structures with the required features, under the suitable constrains. then we ... | 1988 | 1715170 |
| multiple effects of mutation on expression of alternative cell surface protein genes in tetrahymena thermophila. | genes at the serh locus of the ciliated protist tetrahymena thermophila specify the major (h) surface protein on cells grown at 20-36 degrees. alternative proteins l, t, s and i are expressed under different conditions of temperature and culture media. mutants unable to express serh genes were examined for expression of these proteins, also called immobilization or i-antigens, at both h and non-h conditions. in all instances, one or more i-antigens were expressed in the absence of h, and, in mos ... | 1992 | 1732170 |
| conjugal blocks in tetrahymena pattern mutants and their cytoplasmic rescue. i. broadened cortical domains (bcd). | the cortical pattern mutant broadened cortical domains (bcd) in tetrahymena thermophila is unable to complete the nuclear events associated with conjugation. bcd x bcd pairs become arrested at the "nuclear exchange" configuration. genetic analysis reveals that the bcd conjugal block is 100% penetrant, under macronuclear control, and rescueable (a) by outcrossing to a wild-type partner, (b) by administration of a hyperosmotic shock 5 hr after cells are mixed for mating, or (c) by cytoplasmic tran ... | 1991 | 1743392 |
| folding of group i introns from bacteriophage t4 involves internalization of the catalytic core. | fe(ii)-edta, a solvent-based cleavage reagent that distinguishes between the inside and outside surfaces of a folded rna molecule, has revealed some of the higher-order folding of the group ib intron from tetrahymena thermophila pre-rrna. this reagent has now been used to analyze the bacteriophage t4 suny and td introns, both of which are members of the group ia subclass. significant portions of the phylogenetically conserved secondary structure are protected from fe(ii)-edta cleavage. however, ... | 1991 | 1763026 |
| the major pterin in tetrahymena pyriformis is 6-(d-threo-1,2,3-trihydroxypropyl)-pterin (d-monapterin) and not 6-(l-threo-1,2-dihydroxypropyl)-pterin (ciliapterin). | the major pterin in tetrahymena pyriformis, strain w, earlier suggested to be l-threo-biopterin and named ciliapterin [1] is now identified as d-threo-neopterin (d-monapterin). this is the first example of a natural d-monapterin. this compound was characterized by its chromatographic behavior, its fluorescence properties and by its oxidation product with alkaline permanganate. the final identification was obtained by comparison with an authentic material using an exchange ligand chromatography m ... | 1991 | 1782220 |
| pcr amplification of tetrahymena rdna segments starting with individual cells. | to facilitate studies of rdna molecular genetics in tetrahymena thermophila, we attempted the detection of polymorphisms in the nontranscribed spacers (ntss) using polymerase chain reaction (pcr), starting with minute amounts of dna. the targeted polymorphic regions are 85% adenine-thymine (at). we found conditions of efficient and specific in vitro amplification of targeted segments in the replication domain of the 5'nts and in the subtelomeric segment of the 3'nts. the identity of the amplifie ... | 2007 | 1787419 |
| biochemical and cytological evidence for an overabundance of mucocysts in the bcd pattern mutant of tetrahymena thermophila. | three acidic proteins (42 kd, 43 kd and 50 kd) were present in unusually high concentrations in cortical preparations of the tetrahymena pattern mutant broadened cortical domains (bcd). antisera to the 42-kd and 50-kd proteins bound to discharging mucocysts and food vacuole contents in both wild-type and mutant cells. subsequent analysis revealed that bcd mutant cell pellicles possess five times more "docked" mucocysts than their wild-type counterparts. | 2007 | 1818197 |
| implications of ribozyme kinetics for targeting the cleavage of specific rna molecules in vivo: more isn't always better. | kinetic and thermodynamic factors that determine specificity of rna cleavage by ribozymes are illustrated with examples from recent work with a ribozyme derived from the group i intron of tetrahymena thermophila pre-rrna. the conclusions also apply to other ribozymes, to antisense oligonucleotide experiments, and to rna and dna cleavage agents that can recognize a single-stranded or double-stranded region of variable length. at first, adding bases to a ribozyme's recognition sequence is expected ... | 1991 | 1871108 |
| a self-splicing group i intron in the nuclear pre-rrna of the green alga, ankistrodesmus stipitatus. | the nuclear small subunit ribosomal rna gene of the unicellular green alga ankistrodesmus stipitatus contains a group i intron, the first of its kind to be found in the nucleus of a member of the plant kingdom. the intron rna closely resembles the group i intron found in the large subunit rrna precursor of tetrahymena thermophila, differing by only eight nucleotides of 48 in the catalytic core and having the same peripheral secondary structure elements. the ankistrodesmus rna self-splices in vit ... | 1991 | 1886767 |
| purification and some properties of the squalene-tetrahymanol cyclase from tetrahymena thermophila. | the membrane-bound enzyme from tetrahymena thermophila responsible for the conversion of squalene into the quasi-hopanoid tetrahymanol was purified 297-fold to near homogeneity. purification involved solubilization by octylthioglucoside, chromatography on deae-trisacryl, hydroxyapatite and fplc ion-exchange on mono q. the apparent km was found to be 18 microm. 2,3-iminosqualene and n,n-dimethyldodecylamine-n-oxide are effective inhibitors of the cyclase with i50 values of 50 and 30 nm, respectiv ... | 2007 | 1892870 |
| a molecular phylogeny of dinoflagellate protists (pyrrhophyta) inferred from the sequence of 24s rrna divergent domains d1 and d8. | the sequence of two divergent domains (d1 and d8) from dinoflagellate 24s large subunit rrna was determined by primer extension using total rna as template. nucleotide sequence alignments over 401 bases have been analyzed in order to investigate phylogenetic relationships within this highly divergent and taxonomically controversial group of protists of the division pyrrhophyta. data are provided confirming that dinoflagellates represent a monophyletic group. for 11 out of the 13 investigated lab ... | 1991 | 1901368 |
| the main regulatory region of mammalian mitochondrial dna: structure-function model and evolutionary pattern. | the evolution of the main regulatory region (d-loop) of the mammalian mitochondrial genome was analyzed by comparing the sequences of eight mammalian species: human, common chimpanzee, pygmy chimpanzee, dolphin, cow, rat, mouse, and rabbit. the best alignment of the sequences was obtained by optimization of the sequence similarities common to all these species. the two peripheral left and right d-loop domains, which contain the main regulatory elements so far discovered, evolved rapidly in a spe ... | 1991 | 1909377 |
| evaluation of seven in vitro alternatives for ocular safety testing. | seven in vitro assays were evaluated to determine if any were useful as screening procedures in ocular safety assessment. seventeen test materials (chemicals, household cleaners, hand soaps, dishwashing liquids, shampoos, and liquid laundry detergents) were tested in each assay. in vivo ocular irritation scores for the materials were obtained from existing rabbit low volume eye test (lvet) data. the seven assays evaluated included the silicon microphysiometer (sm), luminescent bacteria toxicity ... | 1991 | 1916072 |
| comparison of binding of mixed ribose-deoxyribose analogues of cucu to a ribozyme and to ggagaa by equilibrium dialysis: evidence for ribozyme specific interactions with 2' oh groups. | dissociation constants at 15 degrees c were measured by equilibrium dialysis for the binding of rcrurcru, dcrurcru, rcdurcru, rcrudcru, and rcrurcdu to the l-21 scai form of the self-splicing group i lsu intron from tetrahymena thermophila. substitution of deoxyribose for ribose in each of the middle two positions makes the free energy change for binding 1-2 kcal/mol less favorable, compared to about 0.3 kcal/mol less favorable for each of the terminal positions. dissociation constants for bindi ... | 1991 | 1931984 |
| tetrahymena thermophila acidic ribosomal protein l37 contains an archaebacterial type of c-terminus. | we have cloned and characterized a tetrahymena thermophila macronuclear gene (l37) encoding the acidic ribosomal protein (a-protein) l37. the gene contains a single intron located in the 3'-part of the coding region. two major and three minor transcription start points (tsp) were mapped 39 to 63 nucleotides upstream from the translational start codon. the uppermost tsp mapped to the first t in a putative t. thermophila rna polymerase ii initiator element, tataa. the coding region of l37 predicts ... | 2007 | 1937011 |
| a simplified formaldehyde fixation and immunoprecipitation technique for studying protein-dna interactions. | using the single cell eukaryote tetrahymena thermophila, a simple method was developed for studying protein-dna associations by cross-linking proteins to dna with formaldehyde and immunoprecipitating the solubilized chromatin fragments with a specific antiserum. the protocol uses crude antiserum and involves only three steps: cross-linking, shearing to solubilize the chromatin, and immunoprecipitation. methods for optimizing certain critical parameters, such as fixation time and nacl concentrati ... | 1991 | 1952079 |
| spliceosomal small nuclear rnas of tetrahymena thermophila and some possible snrna-snrna base-pairing interactions. | we have identified and characterized the full set of spliceosomal small nuclear rnas (snrnas; u1, u2, u4, u5 and u6) from the ciliated protozoan tetrahymena thermophila. with the exception of u4 snrna, the sizes of the t. thermophila snrnas are closely similar to their metazoan homologues. the t. thermophila snrnas all have unique 5' ends, which start with an adenine residue. in contrast, with the exception of u6, their 3' ends show some size heterogeneity. the primary sequences of the t. thermo ... | 1991 | 1960724 |