Analyiss of the micronuclear B type surface protein gene in Paramecium tetruaurelia

Scott, J M; Leeck, C L; Forney, James D.

doi:10.1093/nar/22.23.5079

Cited by 43 publications

(43 citation statements)

References 24 publications

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“…IESs that have a common ancestor are unlikely to use radically different excision mechanisms, suggesting that the same mechanism can be differently affected depending on the particular sequence. Paralogous IESs often show limited sequence conservation at their very ends (22,38); the fact that one of the TATT ends of 51G4404 is changed to TATG in 51A4404 can be viewed as supporting the significance of the deviation from the consensus noted above. However, this single criterion is not sufficient to explain the different behaviors of all tested IESs.…”

Section: Discussionmentioning

confidence: 98%

“…In the more closely related Tetrahymena thermophila, the mapping of transient DNA breaks suggests a transposition-like mechanism, in which a staggered double-strand break at one end of the element is followed by a transesterification step that joins the flanking sequences together, releasing the IES as a linear molecule (37). Tetrahymena IESs, however, differ from those of Paramecium and Euplotes in that they lack invariant TA boundaries.The analysis of some 44 kb of Paramecium germ line sequences has revealed a high density of IESs, one every 1,300 bp on average, with no significant difference between coding and noncoding sequences (7,22,38,(41)(42)(43). Although most of the sequences analyzed (35 kb) belong to one multigene family encoding alternative surface antigens, the density of IESs is higher in the remainder of the sequence sample.…”

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confidence: 99%

“…The analysis of some 44 kb of Paramecium germ line sequences has revealed a high density of IESs, one every 1,300 bp on average, with no significant difference between coding and noncoding sequences (7,22,38,(41)(42)(43). Although most of the sequences analyzed (35 kb) belong to one multigene family encoding alternative surface antigens, the density of IESs is higher in the remainder of the sequence sample.…”

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confidence: 99%

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Homology-Dependent Maternal Inhibition of Developmental Excision of Internal Eliminated Sequences inParamecium tetraurelia

Duharcourt

Keller

Meyer

1998

Molecular and Cellular Biology

110

124

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Thousands of single-copy internal eliminated sequences (IESs) are excised from the germ line genome of ciliates during development of the polygenomic somatic macronucleus, following sexual events. Paramecium IESs are short, noncoding elements that frequently interrupt coding sequences. No absolutely conserved sequence element, other than flanking 5-TA-3 direct repeats, has been identified among sequenced IESs; the mechanisms of their specific recognition and precise elimination are unknown. Previous work has revealed the existence of an epigenetic control of excision. It was shown that the presence of one IES in the vegetative macronucleus results in a specific inhibition of the excision of the same element during the development of a new macronucleus, in the following sexual generation. We have assessed the generality and sequence specificity of this transnuclear maternal control by studying the effects of macronuclear transformation with 13 different IESs. We show that at least five of them can be maintained in the new macronuclear genome; sequence specificity is complete both between genes and between different IESs in the same gene. In all cases, the degree of excision inhibition correlates with the copy number of the maternal IES, but each IES shows a characteristic inhibition efficiency. Short internal IES-like segments were found to be excised from two of the IESs when excision between normal boundaries was inhibited. Available data suggest that the sequence specificity of these maternal effects is mediated by pairing interactions between homologous nucleic acids.Ciliates are unicellular eukaryotes in which germ line and somatic functions are assumed by two kinds of nuclei coexisting in the same cytoplasm. The diploid micronuclei are transcriptionally silent during vegetative growth; their main function is to provide gametic nuclei upon meiosis. Vegetative transcription takes place in the polygenomic, somatic macronuclei that divide amitotically and are lost soon after meiosis. Following fertilization, both kinds of nuclei differentiate from copies of the diploid zygotic nucleus. Macronuclear development involves extensive rearrangements of the germ line genome: chromosomes are fragmented into shorter, acentric molecules, and tens of thousands of internally eliminated sequences (IESs) are removed from coding and noncoding sequences, in a reproducible and often highly precise manner. In addition, the genome is amplified to the final ploidy level, ϳ1,000n in Paramecium aurelia complex species (for general reviews, see references 5 and 34; for a review of IESs, see reference 19).All known Paramecium IESs are short (26 to 882 bp), ATrich, single-copy elements flanked by 5Ј-TA-3Ј direct repeats in the germ line sequence. Excision invariably leaves one of the TA repeats in the rearranged macronuclear sequence, suggesting that the same basic mechanism is used for all IESs. Although the excision mechanism is currently unknown, reaction products and intermediates have been identified in other ciliate species. In E...

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Section: Discussionmentioning

confidence: 98%

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confidence: 99%

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confidence: 99%

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Homology-Dependent Maternal Inhibition of Developmental Excision of Internal Eliminated Sequences inParamecium tetraurelia

Duharcourt

Keller

Meyer

1998

Molecular and Cellular Biology

110

124

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“…As in other ciliates, the number of IESs in the genome is probably quite high. Thirteen have been found in the coding sequences and flanking regions of two surface antigen genes, totaling 20 kb (Steele et al 1994;Scott et al 1994b); if these examples are representative, there could be as many as 65,000 IESs per haploid genome. Such a widespread occurrence, similar to that of introns in nuclear genes of some eukaryotes, suggests that most IESs are excised by a common molecular machinery, about which little is known.…”

Section: Duharcourt Et Almentioning

confidence: 99%

Epigenetic self-regulation of developmental excision of an internal eliminated sequence on Paramecium tetraurelia.

Duharcourt¹,

Butler²,

Meyer³

1995

Genes Dev.

141

117

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“…A wild-type stock 51 P. tetraurelia genomic library in AEMBL4 (Scott et al, 1993) was screened by standard methods (Sambrook et al, 1989). Probes were labeled 180-bp dynein fragments obtained by reverse transcriptase (RT)-PCR .…”

Section: Genomic Library Screening and Dna Sequencingmentioning

confidence: 99%

The dynein genes of Paramecium tetraurelia: the structure and expression of the ciliary beta and cytoplasmic heavy chains.

Kandl

Forney

Asai

1995

MBoC

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The genes encoding two Paramecium dynein heavy chains, DHC-6 and DHC-8, have been cloned and sequenced. Sequence-specific antibodies demonstrate that DHC-6 encodes ciliary outer arm beta-chain and DHC-8 encodes a cytoplasmic dynein heavy chain. Therefore, this study is the first opportunity to compare the primary structures and expression of two heavy chains representing the two functional classes of dynein expressed in the same cell. Deciliation of paramecia results in the accumulation of mRNA from DHC-6, but not DHC-8. Nuclear run-on transcription experiments demonstrate that this increase in the steady state concentration of DHC-6 mRNA is a consequence of a rapid induction of transcription in response to deciliation. This is the first demonstration that dynein, like other axonemal components, is transcriptionally regulated during reciliation. Analyses of the sequences of the two Paramecium dyneins and the dynein heavy chains from other organisms indicate that the heavy chain can be divided into three regions: 1) the sequence of the central catalytic domain is conserved among all dyneins; 2) the tail domain sequence, consisting of the N-terminal 1200 residues, differentiates between axonemal and cytoplasmic dyneins; and 3) the N-terminal 200 residues are the most divergent and appear to classify the isoforms. The organization of the heavy chain predicts that the variable tail domain may be sufficient to target the dynein to the appropriate place in the cell.

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Analyiss of the micronuclear B type surface protein gene in Paramecium tetruaurelia

Cited by 43 publications

References 24 publications

Homology-Dependent Maternal Inhibition of Developmental Excision of Internal Eliminated Sequences inParamecium tetraurelia

Homology-Dependent Maternal Inhibition of Developmental Excision of Internal Eliminated Sequences inParamecium tetraurelia

Epigenetic self-regulation of developmental excision of an internal eliminated sequence on Paramecium tetraurelia.

The dynein genes of Paramecium tetraurelia: the structure and expression of the ciliary beta and cytoplasmic heavy chains.

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