| mitochondrial associations with specific microtubular components of the cortex of tetrahymena thermophila. ii. response of the mitochondrial pattern to changes in the microtubule pattern. | mitochondria in tetrahymena thermophila are known to associate with the cell cortex in asymmetrical patterns corresponding to the asymmetrical organization of the microtubular components of the cortex. specific mitochondrion-microtubule associations are seen at the light-microscope and ultrastructural levels. the hypothesis that the mitochondrial pattern is determined by the microtubular pattern was tested. using the phenotypes of various mutations to generate changes in the organization of the ... | 1980 | 7400235 |
| autoradiographic evidence for self-fertilization in tetrahymena thermophila. | | 1980 | 7363953 |
| chromatin structure of the ribosomal rna genes of tetrahymena thermophila as analyzed by trimethylpsoralen crosslinking in vivo. | | 1980 | 7365791 |
| perturbance analysis of nuclear determination in tetrahymena: analysis of mating type frequency variations with reference to binary-switch models. | to test a 3-switch binary element model of mating type determination all possible assignments of the seven mating types of tetrahymena thermophila to compound switch states have been examined, using a set of 77 experimentally obtained frequency patterns as a base. none of the assignments gives a satisfactory agreement with all the data. the result is similar whether the eighth switch state is considered forbidden or redundant. moreover, further explorations of models in which the switches are no ... | 1980 | 7429067 |
| perturbance analysis of nuclear determination in tetrahymena: effects of nutrition, cell extracts, and cacl2 on a/b hybrids. | mating type frequencies were ascertained among the progeny of crosses of strains a x b, tetrahymena thermophila under a number of different circumstances. the frequencies are different if the parents are severely starved than if they are well-fed at the time of conjugation; severe starvation of the progeny before the first post-zygotic division has an effect similar to that of starving the parents. mating type frequencies may also be modified by isolating conjugating pairs into cell extracts bef ... | 1980 | 7429066 |
| in vitro splicing of the ribosomal rna precursor in nuclei of tetrahymena. | the macronuclear rrna genes of tetrahymena thermophila contain a 0.4 kb intervening sequence. in this paper we present evidence that the excision of the intervening sequence from pre-rrna occurs in vitro in isolated t. thermophila nuclei. the transcription-processing system includes alpha-amanitin to inhibit non-rrna synthesis and aurintricarboxylic acid to inhibit endogenous nucleases. a discrete 0.4 kb rna comprises up to 6% of the rna synthesized in this system. southern hybridization with re ... | 1980 | 7357611 |
| chromatin elimination and the genetic organisation of the macronucleus in tetrahymena thermophila. | in exponentially growing tretrahymena thermophila the dna content of the following structures was determined by cytophotometry: macronuclei of sister cells immediately after division; micronuclei; extranuclear chromatin in dividing cells and postdividers. further, the development of macronuclear dna amount in successive cell generations was determined. it was found that chromatin elimination is a frequent process reducing dna content by about 4% per fission. this chromatin disappears within 20 m ... | 1980 | 7389513 |
| modulation of membrane fluidity in a fatty acid auxotrophe of tetrahymena thermophila. | a mutant of tetrahymena thermophila has been isolated which requires an unsaturated fatty acid for growth. pellicles isolated from cultures supplemented with palmitoleic, elaidic, oleic, linoleic and gamma-linolenic acids show widely differing membrane fluidities, as measured by the polarisation of fluorescence technique. in contrast to the behaviour of the wild type organism, the changes in fluidity of the membrane, once induced by supplementation, are permanent. this mutant should prove extrem ... | 1980 | 7349876 |
| an analysis of spindle ultrastructure during anaphase of micronuclear division in tetrahymena. | mitotic micronuclei were isolated from tetrahymena thermophila and data on spindle ultrastructure were obtained from serial, transverse sections. comparison of data from nuclei at meta- and early anaphase with data from nuclei at late anaphase showed that during anaphase, sister kinetochores move from the equator to the spindle poles, but kinetochore translocation occurs without any apparent change in either the number or length of kinetochore microtubules. this unprecedented result is ascribed ... | 1980 | 7348599 |
| galactokinase-deficient mutants of tetrahymena thermophila: selection and characterization. | we have isolated a series of mutants of tetrahymena thermophila which are resistant to inhibition of growth by the galactose analog, 2-deoxygalactose. these mutants were obtained after mutagenesis with nitrosoguanidine and the induction of cytogamy to permit the recovery of recessive mutations induced in the germline micronucleus. resistance to 2-deoxygalactose is correlated with a decreased rate of growth in galactose minimal medium and greatly reduced levels of galactokinase. the resistant phe ... | 1980 | 6934362 |
| 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 |
| 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 |
| 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 |
| mutants of tetrahymena thermophila with temperature sensitive food vacuole formation. ii. physiological and morphological studies. | | 1979 | 315879 |
| 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. 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 |
| 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 |
| 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 |
| 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 |
| mutants of tetrahymena thermophila with temperature-sensitive food vacuole formation. i. isolation and genetic characterization. | germ-line mutants have been isolated in tetrahymena thermophila that have recessive, temperature-sensitive defects in phagocytosis. nitrosoguanidine-mutagenized cells were induced to undergo cytogamy, and clones were isolated that were unable to form food vacuoles after two days of growth at 39 degrees . most of the mutants belong to a single complementation group, designated vaca. they have defects in oral development-not in phagocytosis per se-that are undetectable under light microscopy. one ... | 1979 | 17248939 |
| 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 |
| variability in the timing and outcome of macronuclear assortment in tetrahymena thermophila. | | 1979 | 510923 |
| the functional units of macronuclear assortment in tetrahymena thermophila. | | 1979 | 510922 |
| 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 |
| cytogamy: an inducible, alternate pathway of conjugation in tetrahymena thermophila. | we report the occurrence of cytogamy in tetrahymena thermophila. by analogy to paramecium, cytogamy generates exconjugant clones that derive their entire genetic information from a single meiotic product of their cytoplasmic parent. thus, "instant" whole-genome homozygotes are created. cytogamy has been induced in every strain of t. thermophila tested, and most of the excytogamous progeny have exhibited high fertility. the high frequency with which cytogamy can be induced by hyperosmotic shock, ... | 1979 | 17248904 |
| the pre-pairing events in tetrahymena thermophila. analysis of blocks imposed by high concentrations of tris-cl. | | 1979 | 761602 |
| 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 |
| 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 |
| 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 |
| 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 dna replication schedule is not affected in a division blocked mutant of tetrahymena thermophila. | | 1978 | 720404 |
| 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 |
| 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 |
| transformation in tetrahymena thermophila. development of an inducible phenotype. | | 1978 | 109331 |
| 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 |
| 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 |
| 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 |
| macronuclear subunits of tetrahymena thermophila are functionally haploid. | in tetrahymena thermophila the major argument for the existence of diploid subunits has been that some loci show a delay in the accumulation of stable subclones during macronuclear assortment. this delay is based on the assumption that throughout the life cycle there are 45 subunits. we find that for at least 50 fissions after conjugation there is sufficient dna for 66 haploid subunits. these additional subunits early in the life cycle are sufficient to explain the observed accumulation of stabl ... | 1977 | 17787563 |
| linkage and genetic map length in tetrahymena thermophila. | the genetic map of t. thermophila has been extended with tests of over 170 marker combinations. three linkage groups have been identified, in addition to several apparent linkages which are seen only when certain strains are used. a sampling argument was developed to estimate the total genetic map length from the observed fraction of marker combinations showing linkage. if the strain-dependent linkages are actually due to structural heterozygosity, the total map length is estimated at about 1,20 ... | 1977 | 17248772 |
| 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 |
| 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 |