Infra- and Transspecific Clues to Understanding the Dynamics of Transposable Elements

Vieira, Cristina; Fablet, Marie; Lerat, Emmanuelle

doi:10.1007/7050_2009_044

Cited by 8 publications

(8 citation statements)

References 134 publications

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“…Our collection of natural populations, which provides examples of different tirant dynamics, is an ideal tool for deciphering such mechanisms. Furthermore, it is tempting to propose that these different natural strains illustrate different time periods of the history of the tirant endogenous retrovirus in the D. simulans genome (26). When an active copy of tirant is inserted into a favorable genomic site, it can be transcribed and translated and can retrotranspose to other sites, thereby increasing its copy number.…”

Section: Discussionmentioning

confidence: 99%

tirant , a Newly Discovered Active Endogenous Retrovirus in Drosophila simulans

Akkouche

Rebollo

Burlet

et al. 2012

J Virol

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cEndogenous retroviruses have the ability to become permanently integrated into the genomes of their host, and they are generally transmitted vertically from parent to progeny. With the exception of gypsy, few endogenous retroviruses have been identified in insects. In this study, we describe the tirant endogenous retrovirus in a subset of Drosophila simulans natural populations. By focusing on the envelope gene, we show that the entire retroviral cycle (transcription, translation, and retrotransposition) can be completed for tirant within one population of this species. Endogenous retroviruses are genomic sequences that are widely dispersed throughout the host genome. These sequences constitute 8% of the human genome and represent the remnants of ancient infections by retroviruses (1). Some of these retroviruses were domesticated and generated cellular neogenes, such as the syncytin gene (9, 14). The structure of a canonical endogenous retrovirus consists of three open reading frames (ORFs), which are bordered by long terminal repeats (LTRs). The third ORF encodes the envelope protein (Env), which possesses fusogenic properties and is responsible for the infectious behavior of exogenous retroviruses. In insects, several endogenous retroviruses have been described, and most of them possess a complete retroviral structure. Representative insect endogenous retroviruses (IERVs) or insect ErantiViruses (24) include the following: gypsy, ZAM, Idefix, tirant, 17.6, 297, and nomad in Drosophila melanogaster; tom in Drosophila ananassae; Tv1 in Drosophila virilis; TED in Trichoplusia ni; Osvaldo in Drosophila buzzatii; and Yoyo in Ceratitis capitata (see reference 19 for a review). With the exception of nomad and Tv1, each of these displays a complete env ORF. Thus far, only the well-known gypsy element of D. melanogaster has been shown to possess infectious properties (10), as Moloney murine leukemia virus pseudotypes with the gypsy Env protein were shown to infect insect cells (25).The tirant LTR retrotransposon of D. melanogaster was previously described to share sequence similarity with the fusion proteins of certain baculoviruses (13,16,20) (see Fig. 1 for the tirant structure). In a phylogenetic study of numerous elements from insects, Terzian et al. (24) proposed that the tirant element from D. melanogaster (GenBank accession number X93507) belongs to the IERVs. Thus, the tirant element was placed into this clade of retroviruses, which uses a tRNA-Ser binding site to prime reverse transcription (RT). In the study described in this report, we examined this ERV family in Drosophila simulans using a collection of strains with variable numbers of genomic insertions (7), and we demonstrated that this family was able to produce Env proteins in the ovaries of the host. We found that tirant was capable of performing the first step required for infection, i.e., the production of a functional Env protein, which suggests that it could be classified as an active endogenous retrovirus of D. simulans. Furthermore, we demonstr...

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Section: Discussionmentioning

confidence: 99%

tirant , a Newly Discovered Active Endogenous Retrovirus in Drosophila simulans

Akkouche

Rebollo

Burlet

et al. 2012

J Virol

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“…However, a recent study in humans suggests that histone modifications may also represent an additional mechanism by which TEs can contribute to the regulatory functions of the host genome (101). In Drosophila, the relationship of histone modifications with TE expression has not been demonstrated (102).…”

Section: Regulation By Host Factorsmentioning

confidence: 98%

Evolution of Genome Content: Population Dynamics of Transposable Elements in Flies and Humans

González

Petrov

2012

Methods in Molecular Biology

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Recent research is starting to shed light on the factors that influence the population and evolutionary dynamics of transposable elements (TEs) and TE life cycles. Genomes differ sharply in the number of TE copies, in the level of TE activity, in the diversity of TE families and types, and in the proportion of old and young TEs. In this chapter, we focus on two well-studied genomes with strikingly different architectures, humans and Drosophila, which represent two extremes in terms of TE diversity and population dynamics. We argue that some of the answers might lie in (1) the larger population size and consequently more effective selection against new TE insertions due to ectopic recombination in flies compared to humans; and (2) in the faster rate of DNA loss in flies compared to humans leading to much faster removal of fixed TE copies from the fly genome.

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“…These differences can be related to the TEs themselves, for example, variations in characteristics, such as transposition rates, requirements for host specific factors, mechanisms for transposition control, or even the population's structure of the host species. Populations that are more structured are less prone to disseminate genetic material, including TEs (Vieira et al, 2009). D. willistoni has a large geographical distribution, which extends to areas from Florida to Argentina (Spassky et al, 1971 ;Dobzhansky & Powell, 1975).…”

Section: Resultsmentioning

confidence: 99%

Thecopiaretrotransposon and horizontal transfer inDrosophila willistoni

et al. 2011

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SummaryThe copia element is a retrotransposon that is hypothesized to have been horizontally transferred from Drosophila melanogaster to some populations of Drosophila willistoni in Florida. Here we have used PCR and Southern blots to screen for sequences similar to copia element in South American populations of D. willistoni, as well as in strains previously shown to be carriers of the element. We have not found the canonical copia element in any of these populations. Unlike the P element, which invaded the D. melanogaster genome from D. willistoni and quickly spread worldwide, the canonical copia element appears to have transferred in the opposite direction and has not spread. This may be explained by differences in the requirements for transposition and in the host control of transposition.

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Infra- and Transspecific Clues to Understanding the Dynamics of Transposable Elements

Cited by 8 publications

References 134 publications

tirant , a Newly Discovered Active Endogenous Retrovirus in Drosophila simulans

tirant , a Newly Discovered Active Endogenous Retrovirus in Drosophila simulans

Evolution of Genome Content: Population Dynamics of Transposable Elements in Flies and Humans

Thecopiaretrotransposon and horizontal transfer inDrosophila willistoni

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