Fluorescence in situ hybridization analysis of hobo, mdg1 and Dm412 transposable elements reveals genomic instability following the Drosophila melanogaster genome sequencing

Zakharenko, L. P.; Kovalenko, L. V.; Mai, Sabine

doi:10.1038/sj.hdy.6801029

Cited by 18 publications

(12 citation statements)

References 17 publications

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“…Interestingly, the heterogeneity of the pattern of I fragments in Montpellier changed over time, as suggested by comparing Montpellier flies from different generations (M1, M2, M3). In addition to the I element, the hobo element showed a variable fragment pattern among individuals from the three sublines, in agreement with a recent study showing hobo instability in a y ; cn bw sp line [24].…”

Section: Resultssupporting

confidence: 91%

“…Overall, the results of our cytological and molecular analyses clearly show that I elements are highly unstable in the Montpellier subline in the absence of classical dysgenic conditions. Moreover, our findings confirm and extend the cytological observations by Zhakarenko et al [24], who detected instability of TE families in the y ; cn bw ; sp isogenic strain. In particular, we now report that, at all levels of analysis, the genomic distribution of I elements differs among sublines of the isogenic y ; cn bw sp strain.…”

Section: Discussionsupporting

confidence: 92%

“…By Southern blotting a highly polymorphic pattern of I elements was revealed among individuals of a highly inbred line (N. Junakovic, unpublished). Zakharenko et al [24] extended these observations further to a y ; cn bw sp strain used for the Drosophila melanogaster genome sequencing [25]. This strain is suitable for studying novel changes in the genomic distribution of TEs due to isogenization and presence of phenotypic markers which enable us to distinguish transpositional events from drift of preexisting polymorphisms or contamination.…”

Section: Introductionmentioning

confidence: 96%

See 2 more Smart Citations

Genomic Instability of I Elements of Drosophila melanogaster in Absence of Dysgenic Crosses

Moschetti

Dimitri²,

Caizzi

et al. 2010

PLoS ONE

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Retrotranspostion of I factors in the female germline of Drosophila melanogaster is responsible for the so called I-R hybrid dysgenesis, a phenomenon that produces a broad spectrum of genetic abnormalities including reduced fertility, increased frequency of mutations and chromosome loss. Transposition of I factor depends on cellular conditions that are established in the oocytes of the reactive females and transmitted to their daughters. The so-called reactivity is a cellular state that may exhibit variable levels of expression and represents a permissive condition for I transposition at high levels. Defective I elements have been proposed to be the genetic determinants of reactivity and, through their differential expression, to modulate transposition of active copies in somatic and/or germ line cells. Recently, control of transposable element activity in the germ line has been found to depend on pi-RNAs, small repressive RNAs interacting with Piwi-family proteins and derived from larger transposable elements (TE)-derived primary transcripts. In particular, maternally transmitted I-element piRNAs originating from the 42AB region of polytene chromosomes were found to be involved in control of I element mobility. In the present work, we use a combination of cytological and molecular approaches to study the activity of I elements in three sublines of the inducer y; cn bw; sp isogenic strain and in dysgenic and non-dysgenic genetic backgrounds. Overall, the results of FISH and Southern blotting experiments clearly show that I elements are highly unstable in the Montpellier subline in the absence of classical dysgenic conditions. Such instability appears to be correlated to the amount of 5′ and 3′ I element transcripts detected by quantitative and real-time RT-PCR. The results of this study indicate that I elements can be highly active in the absence of a dysgenic crosses. Moreover, in the light of our results caution should be taken to assimilate the genomic annotation data on transposable elements to all y; cn bw sp sublines.

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Section: Resultssupporting

confidence: 91%

Section: Discussionsupporting

confidence: 92%

Section: Introductionmentioning

confidence: 96%

See 1 more Smart Citation

Genomic Instability of I Elements of Drosophila melanogaster in Absence of Dysgenic Crosses

Moschetti

Dimitri²,

Caizzi

et al. 2010

PLoS ONE

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show abstract

“…Zakharenko et al [28] analyzed the DNA element hobo and the LTR retrotransposons 412 and mdg1 using polytene FISH. Out of 30 expected 412 bands, 4 were deleted with 3 novel insertions.…”

Section: Resultsmentioning

confidence: 99%

Quantitatively Increased Somatic Transposition of Transposable Elements in Drosophila Strains Compromised for RNAi

2013

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In Drosophila melanogaster, small RNAs homologous to transposable elements (TEs) are of two types: piRNA (piwi-interacting RNA) with size 23-29nt and siRNA (small interfering RNA) with size 19-22nt. The siRNA pathway is suggested to silence TE activities in somatic tissues based on TE expression profiles, but direct evidence of transposition is lacking. Here we developed an efficient FISH (fluorescence in Situ hybridization) based method for polytene chromosomes from larval salivary glands to reveal new TE insertions. Analysis of the LTR-retrotransposon 297 and the non-LTR retroposon DOC shows that in the argonaut 2 (Ago2) and Dicer 2 (Dcr2) mutant strains, new transposition events are much more frequent than in heterozygous strains or wild type strains. The data demonstrate that the siRNA pathway represses TE transposition in somatic cells. Nevertheless, we found that loss of one functional copy of Ago2 or Dcr2 increases somatic transpositions of the elements at a lower level depending on the genetic background, suggesting a quantitative role for RNAi core components on mutation frequency.

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“…For example, a high level of hobo and I -element transpositions in the genome of the reference D . melanogaster strain iso-1 is observed despite normal production of hobo - and I -element-specific piRNAs in the ovaries of this strain [5,57,58]. Molecular mechanisms underlying the accumulation of actively transposed copia retrotransposon in the genomes of inbred D .…”

Section: Discussionmentioning

confidence: 99%

Natural variation of piRNA expression affects immunity to transposable elements

et al. 2017

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In the Drosophila germline, transposable elements (TEs) are silenced by PIWI-interacting RNA (piRNA) that originate from distinct genomic regions termed piRNA clusters and are processed by PIWI-subfamily Argonaute proteins. Here, we explore the variation in the ability to restrain an alien TE in different Drosophila strains. The I-element is a retrotransposon involved in the phenomenon of I-R hybrid dysgenesis in Drosophila melanogaster. Genomes of R strains do not contain active I-elements, but harbour remnants of ancestral I-related elements. The permissivity to I-element activity of R females, called reactivity, varies considerably in natural R populations, indicating the existence of a strong natural polymorphism in defense systems targeting transposons. To reveal the nature of such polymorphisms, we compared ovarian small RNAs between R strains with low and high reactivity and show that reactivity negatively correlates with the ancestral I-element-specific piRNA content. Analysis of piRNA clusters containing remnants of I-elements shows increased expression of the piRNA precursors and enrichment by the Heterochromatin Protein 1 homolog, Rhino, in weak R strains, which is in accordance with stronger piRNA expression by these regions. To explore the nature of the differences in piRNA production, we focused on two R strains, weak and strong, and showed that the efficiency of maternal inheritance of piRNAs as well as the I-element copy number are very similar in both strains. At the same time, germline and somatic uni-strand piRNA clusters generate more piRNAs in strains with low reactivity, suggesting the relationship between the efficiency of primary piRNA production and variable response to TE invasions. The strength of adaptive genome defense is likely driven by naturally occurring polymorphisms in the rapidly evolving piRNA pathway proteins. We hypothesize that hyper-efficient piRNA production is contributing to elimination of a telomeric retrotransposon HeT-A, which we have observed in one particular transposon-resistant R strain.

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Fluorescence in situ hybridization analysis of hobo, mdg1 and Dm412 transposable elements reveals genomic instability following the Drosophila melanogaster genome sequencing

Cited by 18 publications

References 17 publications

Genomic Instability of I Elements of Drosophila melanogaster in Absence of Dysgenic Crosses

Genomic Instability of I Elements of Drosophila melanogaster in Absence of Dysgenic Crosses

Quantitatively Increased Somatic Transposition of Transposable Elements in Drosophila Strains Compromised for RNAi

Natural variation of piRNA expression affects immunity to transposable elements

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