Functional separation of genetic factors Telomere elongation (Tel) and Enhancer of terminal gene conversion (E(tc)) involved in telomere elongation in Drosophila melanogaster

ABSTRACT Drosophila telomeres contain arrays of the retrotransposonlike elements HeT-A and TART. Their transposition to broken chromosomal termini has been implicated in chromosome healing and telomere elongation. The HeT-Aelement is attached by its 3′ end, which contains the promoter. To monitor the behavior of HeT-A elements, we used the yellow gene with terminal deficiencies consisting of breaks in theyellow promoter region that result in they-null phenotype. Attachment of the HeT-Aelement provides the promoterless yellow gene with a promoter that activates yellow expression in bristles. The frequency of HeT-A transpositions to the yellowterminal deficiency depends on the genotype of the line and varies from 2 × 10−3 to less than 2 × 10−5. Loss of the attached HeT-A due to incomplete replication at the telomere leads to inactivation of yellow expression, which is restored by attachment of a new HeT-A element upstream of yellow. New HeT-A additions occur at a frequency of about 1.2 × 10−3. Short DNA attachments are generated by gene conversion using the homologous telomeric sequences as templates. Longer DNA attachments are generated either by conventional transposition of an HeT-A element to the chromosomal terminus or by recombination between the 3′ terminus of telomeric HeT-A elements and the receding end ofHeT-A attached to the yellow gene.

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Enhancer of terminal gene conversion, a New Mutation inDrosophila melanogasterThat Induces Telomere Elongation by Gene Conversion

Genetics ◽

10.1093/genetics/162.3.1301 ◽

2002 ◽

Vol 162 (3) ◽

pp. 1301-1312 ◽

Cited By ~ 2

Author(s):

Larisa Melnikova ◽

Pavel Georgiev

Keyword(s):

Drosophila Melanogaster ◽

Gene Conversion ◽

Significant Role ◽

Repeated Sequences ◽

Chromosome 3 ◽

Wild Type ◽

New Mutation ◽

Telomere Elongation ◽

Genotype A

AbstractTelomeres of Drosophila melanogaster contain arrays of the retrotransposon-like elements HeT-A and TART. Terminally deleted chromosomes can be maintained for many generations. Thus, broken chromosome ends behave as real telomeres. It was previously shown that gene conversion may extend the broken ends. Here we found that the frequency of terminal DNA elongation by gene conversion strongly depends on the genotype. A dominant E(tc) (Enhancer of terminal gene conversion) mutation markedly increases the frequency of this event but does not significantly influence the frequency of HeT-A and TART attachment to the broken chromosome end and recombination between directly repeated sequences at the end of the truncated chromosome. The E(tc) mutation was mapped to the 91-93 region on chromosome 3. Drosophila lines that bear the E(tc) mutation for many generations have telomeres, consisting of HeT-A and TART elements, that are longer than those found in wild-type lines. Thus, the E(tc) mutation plays a significant role in the control of telomere elongation in D. melanogaster.

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The Effect of Heterologous Insertions on Gene Conversion in Mitotically Dividing Cells in Drosophila melanogaster

Genetics ◽

10.1093/genetics/161.1.249 ◽

2002 ◽

Vol 161 (1) ◽

pp. 249-258

Author(s):

Angela M Coveny ◽

Tammy Dray ◽

Gregory B Gloor

Keyword(s):

Drosophila Melanogaster ◽

Gene Conversion ◽

Strand Break ◽

Double Strand Break ◽

P Element ◽

Double Strand Break Repair ◽

Break Site ◽

In Trans ◽

Break Repair ◽

In Cis

Abstract We examined the influence that heterologous sequences of different sizes have on the frequency of double-strand-break repair by gene conversion in Drosophila melanogaster. We induced a double-strand break on one X chromosome in female flies by P-element excision. These flies contained heterologous insertions of various sizes located 238 bp from the break site in cis or in trans to the break, or both. We observed a significant decrease in double-strand-break repair with large heterologous insertions located either in cis or in trans to the break. Reestablishing the homology by including the same heterologous sequence in cis and in trans to the double-strand break restored the frequency of gene conversion to wild-type levels. In one instance, an allelic nonhomologous insertion completely abolished repair by homologous recombination. The results show that the repair of a double-strand break by gene conversion requires chromosome pairing in the local region of the double-strand break.

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Identification of the Telomere elongation mutation in Drosophila

10.7287/peerj.preprints.26708 ◽

2018 ◽

Author(s):

Hemakumar M. Reddy ◽

Thomas A. Randall ◽

Radmila Capkova Frydrychova ◽

James M. Mason

Keyword(s):

Drosophila Melanogaster ◽

Next Generation Sequencing ◽

Ltr Retrotransposons ◽

Wild Type ◽

Dominant Mutation ◽

Site Specific ◽

Site Specific Recombination ◽

Telomere Elongation ◽

Drosophila Genetic Reference Panel ◽

Generation Sequencing

Background. Telomeres in Drosophila melanogaster are similar to those of other eukaryotes in terms of their function, although they are formed by non-LTR retrotransposons instead of telomerase-based short repeats. The length of the telomeres in Drosophila depends on the number of copies of these transposable elements. A dominant mutation, Tel1, causes a several-fold elongation of telomeres. Methods. In this study we identified the Tel1 mutation by a combination of transposon-induced, site-specific recombination and next generation sequencing. Results. Recombination located Tel1 to a 15 kb region in 92A. Comparison of the DNA sequence in this region with the Drosophila Genetic Reference Panel of wild type genomic sequences delimited Tel1 to a 3 bp deletion inside intron 8 of Ino80. Discussion. The mapped Tel1 mutation (3-bp deletion found in Ino80) did not appear to affect the quantity or length of the Ino80 transcript. Tel1 causes a significant reduction in transcripts of CG18493, a gene nested in an intron 8 of Ino80, which is expressed in ovaries and expected to encode a serine-type peptidase.

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GENETIC ORGANIZATION IN CAENORHABDITIS ELEGANS: FINE-STRUCTURE ANALYSIS OF THE unc-22 GENE

Genetics ◽

10.1093/genetics/91.1.95 ◽

1979 ◽

Vol 91 (1) ◽

pp. 95-103 ◽

Cited By ~ 4

Author(s):

D G Moerman ◽

D L Baillie

Keyword(s):

Drosophila Melanogaster ◽

Fine Structure ◽

Caenorhabditis Elegans ◽

Gene Conversion ◽

Structure Analysis ◽

Intragenic Recombination ◽

Preliminary Estimate ◽

Recessive Mutations ◽

Fine Structure Analysis ◽

New Alleles

ABSTRACT Fine-structure analysis of the unc-22 gene of Caenorhabditis elegarns has revealed a number of sites that are separable by recombination. Eight new ethyl methanesulfonate-induced recessive mutations of the unc-22 gene have been isolated. Using these new alleles, as well as e66, a number of separable sites have been identified and positioned relative to one another. The map distances obtained are found to be comparable to those associated with intragenic recombination in Drosophila melanogaster, indicating that genetic finestructure analysis is feasible in Caenorhabditis elegans. Evidence of possible gene conversion is presented. A preliminary estimate of the unc-22 gene size is 2.4 × 10-2 map units.

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The Isolation of Polygenic Factors Controlling Bristle Score in Drosophila Melanogaster. II. Distribution of Third Chromosome Bristle Effects within Chromosome Sections.

Genetics ◽

10.1093/genetics/118.3.445 ◽

1988 ◽

Vol 118 (3) ◽

pp. 445-459

Author(s):

A E Shrimpton ◽

A Robertson

Keyword(s):

Drosophila Melanogaster ◽

Standard Deviation ◽

Genetic Factors ◽

Effective Factors ◽

Quantitative Characters ◽

Number Of Factors ◽

Phenotypic Standard Deviation ◽

Degree Of Certainty ◽

Minimum Number ◽

The Difference

Abstract In the present study an attempt has been made to characterize the genetic ;;factors'' controlling quantitative characters, bristle numbers, in Drosophila melanogaster. A low sternopleural bristle multiple recessive marker third chromosome was used to analyze a high sternopleural third chromosome, in a high sternopleural bristle background. An attempt was made to estimate the minimum number of ;;effective factors'' involved in the difference in bristle score between the tested and marker chromosomes. Apart from sternopleural, scutellar and ocellar bristles, a new character, subprimal bristles, was also scored. The unselected characters were used to help in the factor locations, and an attempt made to detect epistasis. Concentrations of bristle effects were found, as were a few ;factors' of large effect. At least 17 sternopleural bristle factors are required to account for the difference in bristle score between the high tested third chromosome and the low tester third chromosome. There was an ascertainment problem for polygenes with effects of less than about 0.6 phenotypic standard deviation. Only an estimate of the minimum number of factors and approximate locations can be given with any degree of certainty. The results are compatible with the hypothesis (among others) that quantitative characters are under the control of a few major genes supported by numerous genes with smaller effect.

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GENE CONVERSION IN HIGHER ORGANISMS: HALF-TETRAD ANALYSIS OF RECOMBINATION WITHIN THE ROSY CISTRON OF DROSOPHILA MELANOGASTER

Genetics ◽

10.1093/genetics/66.2.315 ◽

1970 ◽

Vol 66 (2) ◽

pp. 315-329

Author(s):

Arthur Chovnick ◽

Graeme H Ballantyne ◽

David L Baillie ◽

David G Holm

Keyword(s):

Drosophila Melanogaster ◽

Gene Conversion ◽

Tetrad Analysis

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A Method for Estimating the Mutation, Gene Conversion and Recombination Parameters in Small Multigene Families

Genetics ◽

10.1093/genetics/161.2.865 ◽

2002 ◽

Vol 161 (2) ◽

pp. 865-872 ◽

Cited By ~ 1

Author(s):

Hideki Innan

Keyword(s):

Drosophila Melanogaster ◽

Linkage Disequilibrium ◽

Gene Conversion ◽

Recombination Rate ◽

Multigene Family ◽

Multigene Families ◽

Dna Variation ◽

Conversion Model ◽

Synonymous Sites ◽

Theoretical Results

Abstract A simple two-locus gene conversion model is considered to investigate the amounts of DNA variation and linkage disequilibrium in small multigene families. The exact solutions for the expectations and variances of the amounts of variation within and between two loci are obtained. It is shown that gene conversion increases the amount of variation within each locus and decreases the amount of variation between two loci. The expectation and variance of the amount of linkage disequilibrium are also obtained. Gene conversion generates positive linkage disequilibrium and the degree of linkage disequilibrium decreases as the recombination rate is increased. Using the theoretical results, a method for estimating the mutation, gene conversion, and recombination parameters is developed and applied to the data of the Amy multigene family in Drosophila melanogaster. The gene conversion rate is estimated to be ∼60–165 times higher than the mutation rate for synonymous sites.

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