The nucleotide sequences of copia and copia-related RNA in Drosophila virus-like particles

Emori, Yasufumi; Shiba, Tadayoshi; Kanaya, Shigenori; Inouye, Satoshi; Yuki, Shunji; Saigo, Kaoru

doi:10.1038/315773a0

Cited by 118 publications

(60 citation statements)

References 17 publications

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“…These two elements differ, however, from the I element, which Table 5 Genetic variability indexes on the whole genome, calculated on the simulated hybrids between the inbred lines. NS: labelled site number; NC: number of copies (NC=2NS-NH); NS* and NC*: values including the number of insertions in the centromeric regions; NH: heterozygous site number; Het: proportion of heterozygous sites (Het = NH/NS); PH: probability of heterozygous sites among all the sites observed; A: allelism as defined by Ohta (1985Ohta ( -1986 Emori et a!., 1985), while the P element involves a transposase (Spradling and Rubin, 1982;Engels, 1984). It remains to be seen why the presence of a reverse transcriptase leads to the genomic control of mdg-1, I and copia copy numbers with all these numbers being correlated within a line, whereas the presence of a transposase leads to an independent repartition of the P element on the chromosomes and in the lines.…”

Section: Discussionmentioning

confidence: 99%

Localisation polymorphism of mdg-1, copia, I and P mobile elements in genomes of Drosophila melanogaster, from data of inbred lines

Biémont

Gautier

1988

Heredity

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Using data from in situ hybridisation of the giant chromosomes from salivary glands, mdg-1, I, copia, and P mobile element polymorphism was studied in 17 highly-inbred lines of Drosophila melanogaster and in the expected hybrids obtained from the theoretically-crossed inbred lines. The mean copy numbers of each element on the inbred lines were close and equal to 16-8 for mdg-1, 17•5 for I, 178 for copia and 186 for P (these values included the insertions in the centromeric regions). The P element differed from the other three for variance in copy number and distribution of the number of insertion site occurrences. A low frequency of X-linked copia element insertions (as compared with frequency of insertions in the other chromosomes) was reported, suggesting that natural selection acts against insertional deleterious mutations of this element. Such a low frequency of X-linked insertions was not observed for the other three elements. The mdg-1, I and copia element copy numbers were positively correlated, thus leading to lines with high or low copy number. No correlation was observed between the P element copy number and the numbers of mdg-1, I and copia elements. Moreover, a genomic control of copy number was detected for mdg-1, I and copia, but not for P. The number of labelling sites, the number of copies, the number of heterozygous insertion sites, and various indices of genetic variability were estimated from the expected hybrids obtained from the theoretically-crossed inbred lines; the calculated numbers of labelling sites for mdg-1 and I did not differ from those obtained directly from the initial wild-derived population (we had no estimate of the number of labelling sites available in this population for copia and P). An average proportion of heterozygous sites of 086, 092, 0•90 and 094, and an average number of copies of 33, 35, 38 and 37 were found in the theoretical hybrids for the mdg-1, I, copia and P elements, respectively.

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Section: Discussionmentioning

confidence: 99%

Localisation polymorphism of mdg-1, copia, I and P mobile elements in genomes of Drosophila melanogaster, from data of inbred lines

Biémont

Gautier

1988

Heredity

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“…A major question posed by the observed bidirectional transcription of the solo TED LTR is whether the same (23,38) and copia (9,29), the S. cerevisiae retrotransposon Ty912 (5,8), and the retrovirus human Tlymphotropic virus type III/lymphadenopathy virus (30,39,42,48). …”

Section: Effectsmentioning

confidence: 99%

“…TED also contains a purine-rich region immediately adjacent to the rightmost LTR (data not shown) which may act to initiate second-strand DNA synthesis. Morever, a full-length RNA (7 kb) (19), 17.6 (38), and gypsy bx3 (13) (which is identical to mdg4 [2]) and copia (9,29) (Fig. 5).…”

Section: Effectsmentioning

confidence: 99%

“…The LTRs carry signals necessary for initiation and termination of transcription. The transcribed internal portion of these elements contains several retroviruslike genes, including a gene (pol) with homology to reverse transcriptase (5,9,29,38). In the case of Ty, the full-length RNA extending, from LTR to LTR is copied into DNA by a process identical to that of the retroviruses, suggesting that transposition occurs through reverse transcription of an RNA intermediate (3).…”

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confidence: 99%

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Bidirectional transcription from a solo long terminal repeat of the retrotransposon TED: symmetrical RNA start sites.

Friesen¹,

Rice²,

Miller³

et al. 1986

Mol. Cell. Biol.

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A single copy of the retrotransposon TED was found integrated within the DNA genome of the insect baculovirus, Autographa californica nuclear polyhedrosis virus. After excision of the element from the viral genome, a single long terminal repeat (LTR) remained behind. We have examined the effect of this solo TED LTR on the local pattern of viral transcription. Most prominent was the transcription of two sets of abundant RNAs; both originated within the LTR but extended in opposite directions into flanking viral genes. By promoting symmetric transcription of adjacent genes, the solo LTR has the capacity to activate or repress gene expression in two directions. Primer extension analysis demonstrated that the divergent LTR transcripts were initiated near the same point within a 22-base-pair sequence having hyphenated twofold symmetry. Analogous symmetries at the initiation sites of other retrotransposon LTRs, including copia and Ty, suggested that these sequences serve to establish the precise start for transcription.The retrotransposons represent a group of eucaryotic transposable elements which bear a striking resemblance to the retroviral proviruses (for review, see reference 1). These elements, which include copia and copia-related transposons of Drosophila melanogaster and Ty of Saccharomyces cerevisiae, are flanked at both ends by long terminal repeats (LTRs). The LTRs carry signals necessary for initiation and termination of transcription. The transcribed internal portion of these elements contains several retroviruslike genes, including a gene (pol) with homology to reverse transcriptase (5, 9, 29, 38). In the case of Ty, the full-length RNA extending, from LTR to LTR is copied into DNA by a process identical to that of the retroviruses, suggesting that transposition occurs through reverse transcription of an RNA intermediate (3).By virtue of their ability to integrate randomly into the host genome and alter expression of nearby genes, the retroviruses represent an important class of insertion mutagens (for review, see reference 44). Similarly, the retrotransposons cause insertion mutations in D. melanogaster and S. cerevisiae (reviews in references 35 and 37). Integration within regulatory regions or introns of various genes has resulted in enhancement or inhibition of expression. These alterations occur at the level of transcription and are presumably due to insertion of new promoters, termination signals, or both, located within the retrotransposon. The mutagenic effects of inserted copia, gypsy, and Ty elements are suppressed by additional mutations at unlinked loci which restore transcription of the affected genes to wild-type levels (25,32,51). Mutation of the S. cerevisiae SPT3 (suppressor of Ty) gene, for instance, abolishes normal Ty transcription, which suggests that the mutational effect of certain Ty insertions is due to transcription originating from the element (51). The exact mechanisms involved are still unclear.TED is the first copia-related transposable element iden-

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“…Copia retrotransposon from D melanogaster is 1 of the best known retroviral type elements in the genus Drosophila (Mount and Rubin, 1985;Emori et at, 1985). Retrotransposons are recognized by structural and functional similarities to integrated retroviruses.…”

Section: Introductionmentioning

confidence: 99%

Distribution of the copia transposable element in the repleta group of Drosophila

Francino¹,

Cabre²,

Fontdevila³

1993

Genet. Sel. Evol.

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The nucleotide sequences of copia and copia-related RNA in Drosophila virus-like particles

Cited by 118 publications

References 17 publications

Localisation polymorphism of mdg-1, copia, I and P mobile elements in genomes of Drosophila melanogaster, from data of inbred lines

Localisation polymorphism of mdg-1, copia, I and P mobile elements in genomes of Drosophila melanogaster, from data of inbred lines

Bidirectional transcription from a solo long terminal repeat of the retrotransposon TED: symmetrical RNA start sites.

Distribution of the copia transposable element in the repleta group of Drosophila

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