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Wloga D, Frankel J. From Molecules to Morphology: Cellular Organization of Tetrahymena thermophila. Methods Cell Biol 2012; 109:83-140. [DOI: 10.1016/b978-0-12-385967-9.00005-0] [Citation(s) in RCA: 30] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/04/2023]
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LEICK V, BRO B, LIMA-DE-FARIA A. Scanning electron microscopy of the nuclei and nucleoli in Tetrahymena. Hereditas 2009. [DOI: 10.1111/j.1601-5223.1979.tb01309.x] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022] Open
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GROVE BARBARAF, CONNER ROBERTL. A Procedure for Comparing Growing and Non-growingTetrahymenaCultures: Ribonucleotide Pools inTetrahymenaStarved for the Essential Amino Acid Histidine1. ACTA ACUST UNITED AC 2007. [DOI: 10.1111/j.1550-7408.1988.tb04347.x] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
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Postberg J, Alexandrova O, Lipps HJ. Synthesis of pre-rRNA and mRNA is directed to a chromatin-poor compartment in the macronucleus of the spirotrichous ciliate Stylonychia lemnae. Chromosome Res 2006; 14:161-75. [PMID: 16544190 DOI: 10.1007/s10577-006-1033-x] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/25/2005] [Accepted: 12/27/2005] [Indexed: 10/24/2022]
Abstract
In contrast to the chromosomal genome organization common to most eukaryotes, DNA in the macronucleus of spirotrichous ciliates like Stylonychia lemnae is organized into small gene-sized nanochromosomes. We intended to elucidate whether a spatial organization of nucleoli similar to other eukaryotes can be found in absence of typical chromosomes. Whereas micronuclei of Stylonychia exhibit homogenously stained heterochromatin and possess no nucleoli, macronuclear chromatin is compartmentalized and contains numerous putative nucleoli. Since the identity of these spherical structures has never been unequivocally demonstrated to date, we applied immunofluorescence techniques together with confocal laser scanning microscopy to identify nucleolar bodies in the macronucleus of Stylonychia and to analyse their spatial organization. We found that multiple spherical bodies, which fulfil nucleolar function, occupy a peripheral localization in mature macronuclei. Using fibrillarin/Nop1p as a nucleolar marker, we monitored the assembly of such nucleolar bodies during macronuclear differentiation. 3D-FISH experiments revealed that rRNA genes are mostly concentrated adjacent to but not inside of fibrillarin/Nop1p-containing bodies. We further showed that transcription sites for rRNA synthesis but also for mRNA synthesis occur predominantly at surfaces of nucleolar bodies and chromatin-poor spaces bordering condensed chromatin. Our data suggest that transcription of rRNA genes in the macronucleus of Stylonychia does not rely on a classical nucleolus-type organization. We assume that vectorial synthesis and processing of rRNA and mRNA is directed to a functional interchromatin compartment.
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Affiliation(s)
- Jan Postberg
- Institute of Cell Biology, University of Witten/Herdecke, Stockumer Str. 10, 58453, Witten, Germany.
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Cech TR. Self-splicing and enzymatic activity of an intervening sequence RNA from Tetrahymena. Biosci Rep 2005; 24:362-85. [PMID: 16134019 DOI: 10.1007/s10540-005-2738-3] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/25/2022] Open
Affiliation(s)
- Thomas R Cech
- Howard Hughes Medical Institute, Department of Chemistry and Biochemistry, University of Colorado, Boulder, CO 80309-0215, USA
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Nilsson JR. On macronuclear “subnuclei”, or genome segregation, and “amitosis” in amicronucleate Tetrahymena pyriformis GL. A study utilizing the effect of vanadate on nuclear division. Eur J Protistol 2000. [DOI: 10.1016/s0932-4739(00)80048-6] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
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Affiliation(s)
- K M Karrer
- Department of Biology, Marquette University, Milwaukee, Wisconsin 53201, USA
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Abstract
Ciliates contain two types of nuclei: a micronucleus and a macronucleus. The micronucleus serves as the germ line nucleus but does not express its genes. The macronucleus provides the nuclear RNA for vegetative growth. Mating cells exchange haploid micronuclei, and a new macronucleus develops from a new diploid micronucleus. The old macronucleus is destroyed. This conversion consists of amplification, elimination, fragmentation, and splicing of DNA sequences on a massive scale. Fragmentation produces subchromosomal molecules in Tetrahymena and Paramecium cells and much smaller, gene-sized molecules in hypotrichous ciliates to which telomere sequences are added. These molecules are then amplified, some to higher copy numbers than others. rDNA is differentially amplified to thousands of copies per macronucleus. Eliminated sequences include transposonlike elements and sequences called internal eliminated sequences that interrupt gene coding regions in the micronuclear genome. Some, perhaps all, of these are excised as circular molecules and destroyed. In at least some hypotrichs, segments of some micronuclear genes are scrambled in a nonfunctional order and are recorded during macronuclear development. Vegetatively growing ciliates appear to possess a mechanism for adjusting copy numbers of individual genes, which corrects gene imbalances resulting from random distribution of DNA molecules during amitosis of the macronucleus. Other distinctive features of ciliate DNA include an altered use of the conventional stop codons.
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Affiliation(s)
- D M Prescott
- Department of Molecular, Cellular and Developmental Biology, University of Colorado, Boulder 80309-0347
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Brunk CF, Navas PA. Variable copy number of macronuclear DNA molecules in Tetrahymena. DEVELOPMENTAL GENETICS 1992; 13:111-7. [PMID: 1499152 DOI: 10.1002/dvg.1020130204] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/27/2022]
Abstract
In Tetrahymena, the DNA of the macronucleus exists as very large (100 to 4,000-kb) linear molecules that are randomly partitioned to the daughter cells during cell division. This genetic system leads directly to an assortment of alleles such that all loci become homozygous during vegetative growth. Apparently, there is a copy number control mechanism operative that adjusts the number of each macronuclear DNA molecule so that macronuclear DNA molecules (with their loci) are not lost and aneuploid death is a rare event. In comparing Southern analyses of the DNA from various species of Tetrahymena using histone H4 genes as a probe, we find different band intensities in many species. These differences in band intensities primarily reflect differences in the copy number of macronuclear DNA molecules. The variation in copy number of macronuclear DNA molecules in some species is greater than an order of magnitude. These observations are consistent with a developmental control mechanism that operates by increasing the macronuclear copy number of specific DNA molecules (and the genes located on these molecules) to provide the relatively high gene copy number required for highly expressed proteins.
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Affiliation(s)
- C F Brunk
- Biology Department and Molecular Biology Institute, University of California, Los Angeles
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Cech TR. Selbstspleißen und enzymatische Aktivität einer intervenierenden Sequenz der RNA vonTetrahymena (Nobel-Vortrag). Angew Chem Int Ed Engl 1990. [DOI: 10.1002/ange.19901020705] [Citation(s) in RCA: 19] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
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12
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Cech TR. Nobel lecture. Self-splicing and enzymatic activity of an intervening sequence RNA from Tetrahymena. Biosci Rep 1990; 10:239-61. [PMID: 1699616 DOI: 10.1007/bf01117241] [Citation(s) in RCA: 51] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/28/2022] Open
Abstract
A living cell requires thousands of different chemical reactions to utilize energy, move, grow, respond to external stimuli and reproduce itself. While these reactions take place spontaneously, they rarely proceed at a rate fast enough for life. Enzymes, biological catalysts found in all cells, greatly accelerate the rates of these chemical reactions and impart on them extraordinary specificity. In 1926, James B. Summer crystallized the enzyme urease and found that it was a protein. Skeptics argued that the enzymatic activity might reside in a trace component of the preparation rather than in the protein (Haldane, 1930), and it took another decade for the generality of Summer's finding to be established. As more and more examples of protein enzymes were found, it began to appear that biological catalysis would be exclusively the realm of proteins. In 1981 and 1982, my research group and I found a case in which RNA, a form of genetic material, was able to cleave and rejoin its own nucleotide linkages. This self-splicing RNA provided the first example of a catalytic active site formed of ribonucleic acid. This lecture gives a personal view of the events that led to our realization of RNA self-splicing and the catalytic potential of RNA. It provides yet another illustration of the circuitous path by which scientific inquiry often proceeds. The decision to expand so many words describing the early experiments means that much of our current knowledge about the system will not be mentioned. For a more comprehensive view of the mechanism and structure of the Tetrahymena self-splicing RNA and RNA catalysis in general, the reader is directed to a number of recent reviews (Cech & Bass, 1986: Cech, 1987, 1988a, 1990; Burke, 1988; Altman, 1989). Possible medical and pharmaceutical implications of RNA catalysis have also been described recently (Cech, 1988b).
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Affiliation(s)
- T R Cech
- Howard Hughes Medical Institute, Department of Chemistry and Biochemistry, University of Colorado, Boulder 80309-0215
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Byers TJ. Molecular biology of DNA in Acanthamoeba, Amoeba, Entamoeba, and Naegleria. INTERNATIONAL REVIEW OF CYTOLOGY 1986; 99:311-41. [PMID: 3514511 DOI: 10.1016/s0074-7696(08)61430-8] [Citation(s) in RCA: 55] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/06/2023]
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Radzikowski S. Replication, division and mechanisms controlling the variable DNA content in the heteromeric macronucleus of Chilodonella steini (ciliata). ACTA ACUST UNITED AC 1985. [DOI: 10.1016/s0003-9365(85)80050-6] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/15/2022]
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Dreisig H, Andreasen PH, Kristiansen K. Regulation of ribosome synthesis in Tetrahymena pyriformis. 2. Coordination of synthesis of ribosomal proteins and ribosomal RNA during nutritional shift-up. EUROPEAN JOURNAL OF BIOCHEMISTRY 1984; 140:477-83. [PMID: 6426954 DOI: 10.1111/j.1432-1033.1984.tb08127.x] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/20/2023]
Abstract
The addition of nutrients to long-time-starved cells of Tetrahymena pyriformis leads to a 50-60-fold increase in the rate of synthesis of ribosomal proteins (r-proteins). This is achieved by a 6-fold increase in the relative rate of r-protein synthesis and a 8-10-fold increase in the rate of total protein synthesis. Synthesis of r-proteins constitutes one third of total cellular protein synthesis 2-4 h after refeeding and the absolute rate of r-protein synthesis is approximately three-times greater than in exponentially growing cells. The synthesis of the individual r-proteins is coordinately regulated during a nutritional shift-up, and de novo synthesized r-proteins are stable. Addition of actinomycin D prevents the increase in the rate of r-protein synthesis. The rates of synthesis of rRNA and r-protein increase in concert, implying coordinate regulation. Furthermore, a comparison of the observed accumulation of r-proteins with the predicted accumulation based on the accumulation of rRNA suggests that rRNA and r-protein are synthesized in a stoichiometrically balanced way during the entire refeeding period.
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Gocke E, Bonven BJ, Westergaard O. A site and strand specific nuclease activity with analogies to topoisomerase I frames the rRNA gene of Tetrahymena. Nucleic Acids Res 1983; 11:7661-78. [PMID: 6316268 PMCID: PMC326514 DOI: 10.1093/nar/11.22.7661] [Citation(s) in RCA: 41] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/19/2023] Open
Abstract
Exposure of macronuclear chromatin from Tetrahymena thermophila to sodium dodecyl sulfate causes an endogenous nuclease to cleave the extra-chromosomal rDNA at specific sites. All cuts are single-strand cleavages specific to the non-coding strand. Three cleavages map in the central non-transcribed spacer of the palindromic molecule at positions -1000, -600 and -150 bp with respect to the transcription initiation point. A fourth site is located close to the transcription termination point, while no cleavage is observed in the coding region. The position of each cleavage is in the immediate neighbourhood of DNAse I hypersensitive sites. Additionally, certain DNA sequence motifs are repeated in the region around the cleavages. Upon cleavage induction a protein becomes attached to the rDNA. Our results indicate covalent binding to the generated 3' end, in analogy to the aborted reaction of topoisomerase I.
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Colavito-Shepanski M, Gorovsky MA. The histone content of Tetrahymena ribosomal gene-containing chromatin. J Biol Chem 1983. [DOI: 10.1016/s0021-9258(20)81988-7] [Citation(s) in RCA: 18] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022] Open
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Bonven B, Westergaard O. DNase I hypersensitive regions correlate with a site-specific endogenous nuclease activity on the r-chromatin of Tetrahymena. Nucleic Acids Res 1982; 10:7593-608. [PMID: 6218482 PMCID: PMC327032 DOI: 10.1093/nar/10.23.7593] [Citation(s) in RCA: 23] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/19/2023] Open
Abstract
A novel nuclease activity have been detected at three specific sites in the chromatin of the spacer region flanking the 5'-end of the ribosomal RNA gene from Tetrahymena. The endogenous nuclease does not function catalytically in vitro, but is in analogy with the DNA topoisomerases activated by strong denaturants to cleave DNA at specific sites. The endogenous cleavages have been mapped at positions +50, -650 and -1100 relative to the 5'-end of the pre-35S rRNA. The endogenous cleavage sites are associated with micrococcal nuclease hypersensitive sites and DNase I hypersensitive regions. Thus, a single well-defined micrococcal nuclease hypersensitive site is found approximately 130 bp upstream from each of the endogenous cleavages. Clusters of defined sites, the majority of which fall within the 130 bp regions defined by vicinal micrococcal nuclease and endogenous cleavages, constitute the DNase I hypersensitive regions.
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Vavra KJ, Pederson DS, Gorovsky MA. Nuclease sensitivity of chromatin containing active genes: kinetic analyses utilizing continuous elution of digestion products from an ultrafiltration cell. Nucleic Acids Res 1981; 9:5825-43. [PMID: 6273809 PMCID: PMC327563 DOI: 10.1093/nar/9.21.5825] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/19/2023] Open
Abstract
Methods have been developed to analyze the kinetics of digestion of chromatin by nucleases. Radioactively labeled nuclei were incubated with enzyme in an ultrafiltration apparatus and digestion rates of different chromatin samples were computed employing a least-squares curve fitting technique to fit the data to zero-order and/or first-order kinetic models. These methods allow detailed kinetic analyses on small amounts of chromatin. Two biological systems were studied. 1) Tetrahymena thermophila macronuclei and micronuclei were compared; these nuclei differ in their transcriptional activities. 2) Ribosomal DNA (rDNA) of Tetrahymena pyriformis, approximately 60% of which codes for rRNA, can be preferentially labeled during starvation-refeeding; its digestion kinetics relative to bulk chromatin were studied. DNase I digested 20-40% of the macromolecular DNA about 3 times faster than bulk macronuclear or micronuclear DNA, and 60-80% of ribosomal gene-containing chromatin about 5 times faster than bulk chromatin. Filter hybridization studies of the DNAase I sensitivity of tRNA, 5S RNA, and ribosomal genes yielded similar results. These data are consistent with the observation that transcribed genes are especially sensitive to attach by DNase I and suggest that activated chromatin structure as probed by extensive DNase I digestion is the same in higher and lower eucaryotes for genes transcribed by all three RNA polymerases. Digestion kinetics of micrococcal nuclease were found to depend on the digestion conditions employed. These two biological systems and the methods we have developed should facilitate analyses of the factors responsible for maintaining an active chromatin structure.
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Nilsson JR. On cell organelles in Tetrahymena. With special reference to mitochondria and peroxisomes. ACTA ACUST UNITED AC 1981. [DOI: 10.1007/bf02906518] [Citation(s) in RCA: 24] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/22/2022]
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Nilsson JR, Zeuthen E. On nucleolar DNA replication in Tetrahymena pyriformis GL-8: An electron microscope autoradiographic study of heat synchronized and exponentially multiplying cells. ACTA ACUST UNITED AC 1980. [DOI: 10.1007/bf02906511] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022]
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Giri CP, Gorovsky MA. DNase I sensitivity of ribosomal genes in isolated nucleosome core particles. Nucleic Acids Res 1980; 8:197-214. [PMID: 6766552 PMCID: PMC327252 DOI: 10.1093/nar/8.1.197-e] [Citation(s) in RCA: 43] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/21/2023] Open
Abstract
The level of chromatin structure at which DNase I recognizes conformational differences between inert and activated genes has been investigated. Bulk and ribosomal DNA's of Tetrahymena pyriformis were differentially labeled in vivo with [14C]- and [3H]-thymidine, respectively, utilizing a defined starvation-refeeding protocol. The 3H-labeled ribosomal genes were shown to be preferentially digested by DNase I in isolated nuclei. Staphylococcal nuclease digested the ribosomal genes more slowly than bulk DNA, probably owing to the higher GC content of rDNA. DNase I and staphylococcal nuclease digestions of purified nucleosomes and of nucleosome core particles isolated from dual-labeled, starved-refed nuclei were indistinguishable from those of intact nuclei. We conclude from these studies that DNase I recognizes an alteration in the internal nucleosome core structure of activated ribosomal genes.
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Mathis D, Oudet P, Chambon P. Structure of transcribing chromatin. PROGRESS IN NUCLEIC ACID RESEARCH AND MOLECULAR BIOLOGY 1980; 24:1-55. [PMID: 6256821 DOI: 10.1016/s0079-6603(08)60670-4] [Citation(s) in RCA: 218] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/19/2023]
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24
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Furukawa Y, Yamada RH, Kohno M. Presence of two DNA polymerases in Tetrahymena pyriformis. Nucleic Acids Res 1979; 7:2387-98. [PMID: 118438 PMCID: PMC342391 DOI: 10.1093/nar/7.8.2387] [Citation(s) in RCA: 17] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022] Open
Abstract
Two DNA polymerases were detected in Tetrahymena pyriformis, strain GL. One (enzyme I) was sensitive to N-ethylmaleimide, while the other (enzyme II) was insensitive. The molecular weight of the enzymes, as determined by glycerol gradient centrifugation analysis, were approximately 130,000 and 70,000, respectively. Optimal concentration of MgCl2 was 10mM for enzyme I and 18mM for enzyme II. KCl inhibited enzyme I but stimulated enzyme II. Poly (dA-dT) served effectively as a template for enzyme I, while poly(dA).(dT)12-18 was an effective template for enzyme II. Enzyme I activity increased with cell growth and sharply declined after the cells reached the stationary phase. On the other hand, enzyme II activity appeared only at the end of log phase. In cells synchronized by starvation-refeeding technique enzyme I was markedly stimulated in correspondence to the rate of DNA synthesis, whereas the level of enzyme II activity changed to lesser extent. By ethidium bromide treatment, only enzyme I activity was induced.
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Rodrigues-Pousada C, Cyrne ML, Hayes D. Characterization of preribosomal ribonucleoprotein particles from Tetrahymena pyriformis. EUROPEAN JOURNAL OF BIOCHEMISTRY 1979; 102:389-97. [PMID: 118876 DOI: 10.1111/j.1432-1033.1979.tb04254.x] [Citation(s) in RCA: 33] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Abstract
Ribonucleoprotein particles present in extracts of nuclei prepared from Tetrahymena pyriformis labelled for 1, 2.5, 5 and 10 min with [3H]uridine during exponential growth were analysed by sedimentation through linear 10--30% sucrose gradients. After 1 min of labelling, the early ribosomal RNA precursor (36-S) is found to be associated with slowly sedimenting particles which form a broad peak centred at approximately 50 S. Other kinds of particles sedimenting at 80 S, 66 S, 60 S and 44 S are observed when labelling is carried out for longer periods (2.5, 5 and 10 min). The 80-S particle contains 29-S and 18-S RNA species together with traces of 36-S RNA; the 60-S and 44-S particles contain 26-S and 17-S RNAs respectively. Similar results were obtained when [Me-3H]methionine was used for labelling in place of [3H]uridine. Methylation of the RNA present in slowly sedimenting nuclear components (30-70-S) is rapid, reaching a plateau at 5 min while that of the faster sedimenting (70--90-S) components is still increasing after 10 min. Only three types of ribonucleoprotein particles (80-S, 66-S, and 44-S) were observed when the cells were labelled after prolonged starvation. A scheme of ribosome biogenesis based on these results is presented.
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Lipps HJ, Nock A, Riewe M, Steinbrück G. Chromatin structure in the macronucleus of the ciliate Stylonychia mytilus. Nucleic Acids Res 1978; 5:4699-709. [PMID: 106365 PMCID: PMC342782 DOI: 10.1093/nar/5.12.4699] [Citation(s) in RCA: 30] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022] Open
Abstract
Evidence is presented that macronuclear chromatin in the hypotrichous ciliate Stylonychia mytilus occurs in discrete fragments, each representing at least single genes. The size of these fragments varies between 3 and more than 70 nucleosomes with an average length of about 18 nucleosomes. This observation is discussed with respect to macronuclear structure of hypotrichous ciliates.
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Gocke E, Leer JC, Nielsen OF, Westergaard O. Transcriptional properties of nucleoli isolated from Tetrahymena. Nucleic Acids Res 1978; 5:3993-4006. [PMID: 724506 PMCID: PMC342729 DOI: 10.1093/nar/5.11.3993] [Citation(s) in RCA: 26] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/24/2022] Open
Abstract
Nucleoli can be isolated from Tetrahymena in a yield of 30-60%. The isolated nucleoli contain rDNA (at least 90% pure) and have a protein to DNA ratio of 30:1. The endogenous RNA-polymerase activity of the r-chromatin has the following properties: (i) The in vitro transcript has a maximal size identical to the in vivo 35S rRNA precursor, demonstrating correct termination on the gene, (ii) 79% of the in vitro transcript is complementary to cDNA of 17S and 25S rRNA which is close to the theoretical maximum for the 35S rRNA precursor, (iii) the elongation rate of the endogenous RNA-polymerase molecules is 9-12 nucleotides/sec, (iv) an average of 4-16 active RNA polymerases are associated with each rDNA molecule depending upon the preparation.
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Engberg J, Klenow H. STRUCTURE AND TRANSCRIPTION OF THE FREE RIBOSOMAL RNA GENES IN TETRAHYMENA. Gene Expr 1978. [DOI: 10.1016/b978-0-08-022624-8.50033-8] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/25/2022]
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Andersen HA. Replication and functions of macronuclear DNA in synchronously growing populations of Tetrahymena pyriformis. ACTA ACUST UNITED AC 1977. [DOI: 10.1007/bf02910452] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
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Lykkesfeldt AE. Mechanisms of action of 5-bromodeoxyuridine based on studies with tetrahymena pyriformis. ACTA ACUST UNITED AC 1977. [DOI: 10.1007/bf02906709] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022]
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Yatvin MB, Kintner CR, Elson CE. Letter: Polyribosomes and protein synthesis. A paradoxical effect of oxygen in gamma-irradiated Tetrahymena pyriformis. INTERNATIONAL JOURNAL OF RADIATION BIOLOGY AND RELATED STUDIES IN PHYSICS, CHEMISTRY, AND MEDICINE 1976; 29:589-93. [PMID: 823123 DOI: 10.1080/09553007614550701] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/24/2022]
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Pelvat B, de Haller G. Macronuclear DNA in Stentor coeruleus: a first approach to its characterization. Genet Res (Camb) 1976; 27:277-89. [PMID: 819329 DOI: 10.1017/s0016672300016463] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/24/2022] Open
Abstract
SUMMARYThe macronuclei of Stentor coeruleus were isolated on a discontinuous sucrose gradient and their DNA was purified by conventional methods. The GC content was 32 mole%. The DNA banded as a single peak on analytical ultracentrifugation at 1·691 g/cm3. The molecular weight of the DNA was 5 × 106 to 4 × 107 daltons. Genome size determined by DNA–DNA reassociation kinetics was 6 × 1010 daltons. The macronuclear genome was mostly simple, about 85% being made of non-repetitive sequences.
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Tonnesen T, Engberg J, Leick V. Studies on the amount and location of the tRNA and 5-S rRNA genes in Tetrahymena pyriformis GL. EUROPEAN JOURNAL OF BIOCHEMISTRY 1976; 63:399-407. [PMID: 816653 DOI: 10.1111/j.1432-1033.1976.tb10241.x] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/24/2022]
Abstract
The amount and location of tRNA and 5-S rRNA genes in the macronucleus of Tetrahymena pyriformis GL was investigated by DNA-RNA hybridization. Hybridization of 32P-labelled tRNA in excess of unlabelled rRNA (25-S + 17-S + 5-S) showed that at saturation 0.021% of the macronuclear DNA was complementary to tRNA. Hybridization of 32P-labelled 5-S rRNA in excess of unlabelled 25-S + 17-S rRNA and tRNA showed a saturation value of 0.017%. In contrast to the 25-S + 17-S rRNA genes, which are found in DNA of high bouyant density, tRNA and 5-S rRNA genes were distributed evenly throughout the main peak observed when bulk macronuclear DNA was fractionated by density centrifugation in CsCl gradients. Sucrose gradient analyses of total macronuclear DNA showed that tRNA and 5-S rRNA genes were found in DNA of all size classes but a significant enrichment in the slowly sedimenting DNA fraction was observed. Saturation hybridization of 5-S rRNA to purified rDNA showed that rDNA did not contain any 5-S rRNA genes.
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Piper PW, Celis J, Kaltoft K, Leer JC, Nielsen OF, Westergaard O. Tetrahymena ribosomal RNA gene chromatin is digested by micrococcal nuclease at sites which have the same regular spacing on the DNA as corresponding sites in the bulk nuclear chromatin. Nucleic Acids Res 1976; 3:493-505. [PMID: 815891 PMCID: PMC342918 DOI: 10.1093/nar/3.2.493] [Citation(s) in RCA: 42] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/24/2022] Open
Abstract
Synchronised cells of Tetrahymena pyriformis GL were labelled with 3H thymidine at a stage in the cell cycle when only the mitochondrial and extrachromosomal nucleolar ribosomal DNAs were replicating. In this way it was possible to prepare nuclei labelled selectively in the DNA of the ribosomal RNA genes. Since the ribosomal RNA cistrons of these cells are also very active in serving as a template for transcription, experiments were performed to test whether these genes are organised upon a nucleoprotein subunit structure of the kind that has been found in the total chromatin of a wide range of eukaryotic cell types. Tetrahymena macronuclei were prepared labelled uniformly in their DNA with 32P and labelled only in their nucleolar ribosomal DNA with 3H. Both the ribosomal genes and the bulk chromatin were then degraded in situ using micrococcal nuclease. The DNA fragments resulting from mild digestion were analysed on gels to reveal an identical DNA degradation pattern within both the ribosomal and bulk chromatins. It is concluded that the nucleoprotein structure of nucleolar rRNA cistrons posesses a periodic repeat along the DNA which is identical to that found in the substructure of unfractionated chromatin.
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Spear BB, Lauth MR. Polytene chromosomes of Oxytricha: biochemical and morphological changes during macronuclear development in a ciliated protozoan. Chromosoma 1976; 54:1-13. [PMID: 813980 DOI: 10.1007/bf00331828] [Citation(s) in RCA: 50] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/24/2022]
Abstract
After conjugation in the ciliated protozoan, Oxytricha, polytene chromosomes are formed during the development of a macronucleus from a micronucleus. Here we report a microscopic study of these chromosomes and an analysis of their DNA. The polytene chromosomes of Oxytricha bear a strong morphological resemblance to the polytene chromosomes of the Dipteran salivary gland. The nucleus of a developing macronuclear anlage contains 120 +/- 2 polytene chromosomes and each chromosome has an average of 81 hands; a total of about 10,000 bands per nucleus. At a later stage in development, the number of bands per chromosome is reduced by a factor of four, presumably due to fusion of adjacent bands. The polytene chromosomes then break up into their constituent bands, each of which is encased in a vesicle. There are about 2,700 vesicles per nucleus.--During the growth of polytene chromosomes, there is a change in the relative proportion of sequences in the DNA. The DNA from polytene nuclei has a buoyant density of 1.695 g/cc, significantly lighter than the density of the original micronuclear DNA (1.698 G/cc to 1.702 g/cc). We interpret this buoyant density change to be the result of differential replication of DNA sequences during polytene chromosome growth. A second change in DNA composition occurs after the polytene stage of development, shown by a shift in buoyant density to 1.701 g/cc in the DNA of the mature macronucleus. During this second process, the molecular weight of the DNA is reduced from greater than 50 x 10(6) daltons to about 2 x 10(6) daltons.
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Ernst SG, Rustad RC, Oleinick NL. Radiation-induced inhibition of RNA synthesis in Tetrahymena pyriformis. INTERNATIONAL JOURNAL OF RADIATION BIOLOGY AND RELATED STUDIES IN PHYSICS, CHEMISTRY, AND MEDICINE 1975; 28:67-74. [PMID: 810444 DOI: 10.1080/09553007514550771] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/24/2022]
Abstract
Radiation-induced disturbances in RNA synthesis were investigated in exponentially growing Tetrahymena. Sub-lethal doses of gamma-radiation lead to a transient, dose-dependent decrease in the rate of total RNA synthesis measured by 3H-uridine incorporation, without an alteration of 3H-uridine uptake by the cells. The rate of 3H-uridine incorporation decreases exponentially with dose. In contrast, the duration of inhibition of RNA synthesis is linearly dependent on dose. Target-theory calculations suggest that the sensitive molecule has a molecular weight of about 2 X 10(7) Daltons.
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Mowat D, Pearlman RE. Excision repair in Tetrahymena: events following refeeding of starved UV-irradiated cells. Photochem Photobiol 1975; 21:5-11. [PMID: 805439 DOI: 10.1111/j.1751-1097.1975.tb06622.x] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.0] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/24/2022]
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Andersen HA, Rasmussen L, Zeuthen E. Cell division and DNA replication in synchronous Tetrahymena cultures. Curr Top Microbiol Immunol 1975; 72:1-20. [PMID: 815074 DOI: 10.1007/978-3-642-66289-8_1] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/24/2022]
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Abstract
In the macronucleus of the ciliated protozoan, Tetrahymena pyriformis GL, the genes coding for 17S and 25S rRNA exist as free, extrachromosomal molecules. About 90% of the molecules are linear with a molecular weight of 12.6 x 10(6). Most of the remainder are circles of the same size, or lariats (circles with tails). A few dimers and oligomers are found. The extrachromosomal rDNA of Tetrahymena represents a kind of gene amplification that may be common among primitive eukaryotes.
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Yao MC, Kimmel AR, Gorovsky MA. A small number of cistrons for ribosomal RNA in the germinal nucleus of a eukaryote, Tetrahymena pyriformis. Proc Natl Acad Sci U S A 1974; 71:3082-6. [PMID: 4606151 PMCID: PMC388625 DOI: 10.1073/pnas.71.8.3082] [Citation(s) in RCA: 86] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/11/2023] Open
Abstract
The percentage of DNA complementary to 25S and 17S rRNA has been determined for both the macro- and micronucleus of the ciliated protozoan, Tetrahymena pyriformis. Saturation levels obtained by DNA.RNA hybridization indicate that approximately 200 copies of the gene for rRNA per haploid genome were present in macronuclei. The saturation level obtained with DNA extracted from isolated micronuclei was only 5-10% of the level obtained with DNA from macronuclei. After correction for contamination of micronuclear DNA by DNA from macronuclei, only a few copies (possibly only 1) of the gene for rRNA are estimated to be present in micronuclei. Micronuclei are germinal nuclei. Macronuclei serve as somatic nuclei during vegetative growth but are destroyed every sexual generation and are reformed from products of meiosis, fertilization, and division of the micronuclei. Thus, the hybridization data suggest that the gene for rRNA must be amplified during macronuclear formation with each sexual generation. These observations also demonstrate that the multiple copies of a repeated gene in a somatic nucleus of a eukaryote can be generated from a small number of copies of that gene in a germinal nucleus.
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Yao MC, Gorovsky MA. Comparison of the sequences of macro- and micronuclear DNA of Tetrahymena pyriformis. Chromosoma 1974; 48:1-18. [PMID: 4218159 DOI: 10.1007/bf00284863] [Citation(s) in RCA: 172] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/09/2023]
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