Nucleo-Cytoplasmic Interaction During Conjugation in Tetrahymena

Nanney, D. L.

doi:10.2307/1538562

Cited by 162 publications

(61 citation statements)

References 8 publications

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“…Although transcription is not detected in these nuclei, they may still have the potential to transcribe since they possess a critical component of this process (TBP). Consistent with this, these nuclei still retain the capacity to develop into macronuclei when they are relocated to the anterior cytoplasm (50). Anti-TBP staining is finally lost from developing micronuclei very late in conjugation, approximately coincident with the time that differentiating macronuclei become transcriptionally active and the parental macronucleus is degraded.…”

Section: Mdfalpt Tasqasafmn Nssltfpvlp Nanneatnet Adsgdaevsk --------supporting

confidence: 54%

“…Differentiation of the four products of the second postzygotic division into macronuclei or micronuclei is specified by their location in the cytoplasm: the two anterior nuclei develop into macronuclei while the two posterior nuclei become micronuclei. Results obtained by Nanney (50) strongly support a determinative role of localized cytoplasmic regions, since nuclei relocated to the anterior region by centrifugation developed into macronuclei, while those relocated to the posterior region became micronuclei. The differentiation of macronuclei is characterized by striking MOL.…”

Section: Mdfalpt Tasqasafmn Nssltfpvlp Nanneatnet Adsgdaevsk --------mentioning

confidence: 70%

See 1 more Smart Citation

TATA-binding protein and nuclear differentiation in Tetrahymena thermophila.

Stargell¹,

Gorovsky²

1994

Mol. Cell. Biol.

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Unambiguous TATA boxes have not been identified in upstream sequences of Tetrahymena thermophila genes analyzed to date. To begin a characterization of the promoter requirements for RNA polymerase II, the gene encoding TATA-binding protein (TBP) was cloned from this species. The derived amino acid sequence for the conserved C-terminal domain of Tetrahymena TBP is one of the most divergent described and includes a unique 20-amino-acid C-terminal extension. Polyclonal antibodies generated against a fragment of Tetrahymena TBP recognize a 36-kDa protein in macronuclear preparations and also cross-react with yeast and human TBPs.Immunocytochemistry was used to examine the nuclear localization of TBP during growth, starvation, and conjugation (the sexual phase of the life cycle). The transcriptionaily active macronuclei stained at all stages of the life cycle. The transcriptionally inert micronuclei did not stain during growth or starvation but surprisingly stained with anti-TBP throughout early stages of conjugation. Anti-TBP staining disappeared from developing micronuclei late in conjugation, corresponding to the onset of transcription in developing macronuclei. Since micronuclei do not enlarge or divide at this time, loss of TBP appears to be an active process. Thus, the transcriptional differences between macro-and micronuclei that arise during conjugation are associated with the loss of a major component of the basal transcription apparatus from developing micronuclei rather than its appearance in developing macronuclei.TATA-binding protein (TBP) is required for transcription by all three nuclear RNA polymerases. TBP, along with an assortment of distinct TBP-associated factors, has been found to make up the RNA polymerase I selectivity factor I (9, 36), the polymerase II general transcription factor IID (14,73,83), and the RNA polymerase III general transcription factor IIIB (38,43,62,72,75). Given the need for TBP to function in these different complexes in such fundamental cellular processes, it is not surprising that TBP is highly conserved throughout eukaryotes. Yeast and human TBP are functionally interchangeable in basal transcription reactions reconstituted with yeast or human components (5,17,39) and have nearly identical TATA element binding specificities (78). The C-terminal 180 residues of TBP from a variety of organisms are typically 80% identical in amino acid sequence, whereas the N-terminal regions are divergent both in length and in amino acid sequence (6, 16, 20, 26, 28-30, 33, 37, 49, 55, 61). The C-terminal domain is necessary and sufficient for TATA element binding and basal transcription in vitro (28,41,55) and for the essential functions of yeast TBP in yeast cells (10,21,57,84). This region forms an independent structural domain within the context of the intact protein (41). It contains an interrupted repeat of 67 amino acids, a short basic repeat, and a region weakly homologous with bacterial sigma factors (10, 80). In addition to its role in the basal transcription apparatus, TBP also ...

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Section: Mdfalpt Tasqasafmn Nssltfpvlp Nanneatnet Adsgdaevsk --------supporting

confidence: 54%

Section: Mdfalpt Tasqasafmn Nssltfpvlp Nanneatnet Adsgdaevsk --------mentioning

confidence: 70%

TATA-binding protein and nuclear differentiation in Tetrahymena thermophila.

Stargell¹,

Gorovsky²

1994

Mol. Cell. Biol.

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“…4a). Nanney's results (Nanney 1953) strongly support a determinative role of localized cytoplasmic regions, as nuclei relocated to the anterior region by centrifugation develop into macronuclei, whereas those relocated to the posterior region become micronuclei. At later stages developing macro-and micronuclei come together near the center of the cell, and position is no longer important.…”

Section: Discussionmentioning

confidence: 88%

Temporal and spatial association of histone H2A variant hv1 with transcriptionally competent chromatin during nuclear development in Tetrahymena thermophila.

Stargell¹,

Bowen²,

Dadd³

et al. 1993

Genes & Development

120

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Vegetative cells of the ciliated protozoan Tetrahymena thermophila contain a transcriptionally active macronucleus and a transcriptionally inactive micronucleus. Although structurally and functionally dissimilar, these nuclei are products of a single postzygotic division during conjugation, the sexual phase of the life cycle. Immunocytochemical analyses during growth, starvation, and conjugation were used to examine the nuclear deposition of hvl, a histone H2A variant that is found in macronuclei and thought to play a role in transcriptionally active chromatin. Polyclonal antisera were generated using whole hvl protein and synthetic peptides from the amino and carboxyl domains of hvl. The transcriptionally active macronuclei stained at all stages of the life cycle. Micronuclei did not stain during growth or starvation but stained with two of the sera during early stages of conjugation, preceding the stage when micronuclei become transcriptionally active. Immunoblot analyses of fractionated macro-and micronuclei confirmed the micronuclear acquisition of hvl early in conjugation, hvl staining disappeared from developing micronuclei late in conjugation. Interestingly, the carboxy-peptide antiserum stained micronuclei only briefly, late in development. The detection of the previously sequestered carboxyl terminus of hvl may be related to the elimination of hvl during the dynamic restructuring of micronuclear chromatin that occurs as the micronucleus enters a transcriptionally incompetent state that is maintained during vegetative growth. These studies demonstrate that the transcriptional differences between macro-and micronuclei are associated with the loss of a chromatin component from developing micronuclei rather than its de novo appearance in developing macronuclei and argue that hvl functions in establishing a transcriptionally competent state of chromatin.

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“…Most importantly, in addition to discussing variability in expression patterns, Nanney (1958a) emphasized the fact that expression states could persist through cell division. Although some have claimed that Nanney's usage of the term epigenetic was developed independently of Waddington's definition (he initially used the term paragenetic) (Haig 2004), considerable overlap can be found in their contemporary writings on genotype-phenotype relationships (Nanney et al 1955(Nanney et al , 1958aWaddington 1939Waddington , 1942a, gene expression (Nanney et al 1955(Nanney et al , 1958aWaddington 1939Waddington , 1942a, and the respective roles of the nucleus and the cytoplasm in gene regulation (Nanney 1953(Nanney , 1957(Nanney , 1958aWaddington 1939Waddington , 1956. It is clear, however, that Nanney's contemplation of the stability of cellular expression states was an important addition to Waddington's ideas, which had significant impacts on the future direction of epigenetics.…”

Section: History Of the Term "Epigenetic"mentioning

confidence: 99%

What Do You Mean, “Epigenetic”?

2015

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Interest in the field of epigenetics has increased rapidly over the last decade, with the term becoming more identifiable in biomedical research, scientific fields outside of the molecular sciences, such as ecology and physiology, and even mainstream culture. It has become increasingly clear, however, that different investigators ascribe different definitions to the term. Some employ epigenetics to explain changes in gene expression, others use it to refer to transgenerational effects and/or inherited expression states. This disagreement on a clear definition has made communication difficult, synthesis of epigenetic research across fields nearly impossible, and has in many ways biased methodologies and interpretations. This article discusses the history behind the multitude of definitions that have been employed since the conception of epigenetics, analyzes the components of these definitions, and offers solutions for clarifying the field and mitigating the problems that have arisen due to these definitional ambiguities.

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Nucleo-Cytoplasmic Interaction During Conjugation in Tetrahymena

Cited by 162 publications

References 8 publications

TATA-binding protein and nuclear differentiation in Tetrahymena thermophila.

TATA-binding protein and nuclear differentiation in Tetrahymena thermophila.

Temporal and spatial association of histone H2A variant hv1 with transcriptionally competent chromatin during nuclear development in Tetrahymena thermophila.

What Do You Mean, “Epigenetic”?

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