hAT Transposon Research Articles

Enriched tandem repeats in chromosomal fusion points of Rineloricaria latirostris (Boulenger, 1900) (Siluriformes: Loricariidae).

Cytogenetic data showed the enrichment of repetitive DNAs in chromosomal rearrangement points between closely related species in armored catfishes. Still, few studies integrated cytogenetic and genomic data aiming to identify their prone-to-break DNA sites. Here, we aimed to obtain the repetitive fraction in Rineloricaria latirostris to recognize the microsatellite and homopolymers flanking the regions previously described as chromosomal fusion points. The results indicated that repetitive DNAs in R. latirostris are predominantly DNA transposons, and considering the microsatellite and homopolymers, A/T-rich expansions were the most abundant. The in situ localization demonstrated the A/T-rich repetitive sequences were scattered on the chromosomes, while A/G-rich microsatellite units were accumulated in some regions. The DNA transposon hAT, the 5S rDNA, and 45S rDNA (previously identified in Robertsonian fusion points in R. latirostris) were clusterized with some microsatellites, especially (CA)n, (GA)n, and poly-A, which were also enriched in regions of chromosomal fusions. Our findings demonstrated that repetitive sequences such as rDNAs, hAT transposons, and microsatellite units flank probable evolutionary breakpoint regions in R. latirostris. However, due to the sequence unit homologies in different chromosomal sites, these repeat DNAs only may facilitate chromosome fusion events in R. latirostris rather than working as a double-strand breakpoint site.

The genetic control of glabrous glume during African rice domestication

African cultivated rice, Oryza glaberrima, is characterized by its glabrous glumes. During domestication, the pubescent glumes of its wild ancestor, Oryza barthii, lost their trichomes, and in this study, we show that glabrous glume 5 (GLAG5), a WUSCHEL-like homeobox transcription factor gene on chromosome 5, is required for trichome development. DNA methylation associated with an hAT transposable element inserted in the promoter region of GLAG5 is found to reduce its expression, leading to the formation of glabrous glumes and leaves in African cultivated rice. Among 82 African cultivated rice varieties investigated in this study, 59 (approximately 71%) lines exhibit glabrous glumes and harbor the hAT transposon; however, the other 23 varieties (approximately 29%), which exhibit pubescent glumes, lack the hAT transposon, indicating that glag5 had undergone strong artificial selection. The πw/πc ratios also show the hAT transposon insertions influence the genetic diversity of an approximately 150-kb interval encompassing the GLAG5 locus. The identification of the GLAG5 gene provides new insights into the domestication of cultivated rice in Africa. We speculate that the selection of varieties with mutations in their promoter regions is an important aspect of crop domestication.

Interpopulation variation of transposable elements of the hAT superfamily in Drosophila willistoni (Diptera: Drosophilidae): in-situ approach.

Transposable elements are abundant and dynamic part of the genome, influencing organisms in different ways through their presence or mobilization, or by acting directly on pre- and post-transcriptional regulatory regions. We compared and evaluated the presence, structure, and copy number of three hAT superfamily transposons (hobo, BuT2, and mar) in five strains of Drosophila willistoni species. These D. willistoni strains are of different geographical origins, sampled across the north-south occurrence of this species. We used sequenced clones of the hAT elements in fluorescence in-situ hybridizations in the polytene chromosomes of three strains of D. willistoni. We also analyzed the structural characteristics and number of copies of these hAT elements in the 10 currently available sequenced genomes of the willistoni group. We found that hobo, BuT2, and mar were widely distributed in D. willistoni polytene chromosomes and sequenced genomes of the willistoni group, except for mar, which is restricted to the subgroup willistoni. Furthermore, the elements hobo, BuT2, and mar have different evolutionary histories. The transposon differences among D. willistoni strains, such as variation in the number, structure, and chromosomal distribution of hAT transposons, could reflect the genomic and chromosomal plasticity of D. willistoni species in adapting to highly variable environments.

Global Methylomic and Transcriptomic Analyses Reveal the Broad Participation of DNA Methylation in Daily Gene Expression Regulation of Populus trichocarpa.

Changes in DNA methylation patterns in different tissues, at various developmental stages, and under environmental stimuli have been investigated in plants. However, the involvement of DNA methylation in daily gene expression regulation and the plant circadian clock have not been reported. Here, we investigated DNA methylomes and mRNA transcriptomes from leaves of P. trichocarpa over 24 h by high-throughput sequencing. We found that approximately 15.63–19.50% of the genomic cytosine positions were methylated in mature poplar leaves, with approximately half being in the form of asymmetric CHH sites. Repetitive sequences and transposable elements (TEs) were heavily methylated, and the hAT and CMC-EnSpm transposons were more heavily methylated than other TEs. High methylation levels were observed upstream and downstream of the transcribed region, medium in exon and intron, low in untranslated region (5′-UTR and 3′-UTR) of genic regions. In total, about 53,689 differentially methylated regions (DMRs) were identified and CHH context was the most abundant type among daily DNA methylation changes. The DMRs overlapped with over one third of the total poplar genes, including plant defense genes. In addition, a positive correlation between expression levels and DNA methylation levels in the gene body region were observed in DMR overlapping genes. About 1,895 circadian regulated genes overlapped with DMRs, with 871 hypermethylated genes with down-regulated expression levels and 881 hypomethylated genes with up-regulated expression levels, indicating the possible regulation of DNA methylation on the daily rhythmic expression of these genes. But rhythmic DNA methylation changes were not detected in any oscillator component genes controlling the plant circadian clock. Our results suggest that DNA methylation participates widely in daily gene expression regulation, but is not the main mechanism modulating the plant circadian clock.

In silico Phylogenetic Analysis of hAT Transposable Elements in Plants

Transposable elements of the hAT family exhibit a cross-kingdom distribution. The plant hAT transposons are proposed to play a critical role in plant adaptive evolution and DNA damage repair. The sequencing of an increasing number of plant genomes has facilitated the discovery of a plethora of hAT elements. This enabled us to perform an in-depth phylogenetic analysis of consensus hAT sequences in the fully-sequenced genomes of 11 plant species that represent diverse taxonomic divisions. Four putative nucleotide sequences were detected in cottonwood that were similar to the corresponding animal hAT elements, which are possibly sequence artifacts. Phylogenetic trees were constructed based both on the known and putative hAT sequences, by employing two different methods of phylogenetic inference. On the basis of the reconstructed phylogeny, plant hAT elements have rather evolved through kingdom-specific vertical gene transfer and gene amplifications within eudicotyledons, monocotyledons, and chlorophytes. Furthermore, the plant hAT sequences were searched for conserved DNA and amino acid sequence features. In this way, diagnostic sequence patterns were detected which allowed us to assign functional annotations to the plant hAT sequences.

Two hAT transposon genes were transferred from Brassicaceae to broomrapes and are actively expressed in some recipients.

A growing body of evidence is pointing to an important role of horizontal gene transfer (HGT) in the evolution of higher plants. However, reports of HGTs of transposable elements (TEs) in plants are still scarce, and only one case is known of a class II transposon horizontally transferred between grasses. To investigate possible TE transfers in dicots, we performed transcriptome screening in the obligate root parasite Phelipanche aegyptiaca (Orobanchaceae), data-mining in the draft genome assemblies of four other Orobanchaceae, gene cloning, gene annotation in species with genomic information, and a molecular phylogenetic analysis. We discovered that the broomrape genera Phelipanche and Orobanche acquired two related nuclear genes (christened BO transposase genes), a new group of the hAT superfamily of class II transposons, from Asian Sisymbrieae or a closely related tribe of Brassicaceae, by HGT. The collinearity of the flanking genes, lack of a classic border structure, and low expression levels suggest that BO transposase genes cannot transpose in Brassicaceae, whereas they are highly expressed in P. aegyptiaca.

Pinpointing the vesper bat transposon revolution using the Miniopterus natalensis genome.

BackgroundAround 40 million years ago DNA transposons began accumulating in an ancestor of bats in the family Vespertilionidae. Since that time, Class II transposons have been continuously reinvading and accumulating in vespertilionid genomes at a rate that is unprecedented in mammals. Miniopterus (Miniopteridae), a genus of long-fingered bats that was recently elevated from Vespertilionidae, is the sister taxon to the vespertilionids and is often used as an outgroup when studying transposable elements in vesper bats. Previous wet-lab techniques failed to identify Helitrons, TcMariners, or hAT transposons in Miniopterus. Limitations of those methods and ambiguous results regarding the distribution of piggyBac transposons left some questions as to the distribution of Class II elements in this group. The recent release of the Miniopterus natalensis genome allows for transposable element discovery with a higher degree of precision.ResultsHere we analyze the transposable element content of M. natalensis to pinpoint with greater accuracy the taxonomic distribution of Class II transposable elements in bats. These efforts demonstrate that, compared to the vespertilionids, Class II TEs are highly mutated and comprise only a small portion of the M. natalensis genome. Despite the limited Class II content, M. natalensis possesses a limited number of lineage-specific, low copy number piggyBacs and shares several TcMariner families with vespertilionid bats. Multiple efforts to identify Helitrons, one of the major TE components of vesper bat genomes, using de novo repeat identification and structural based searches failed.ConclusionsThese observations combined with previous results inform our understanding of the events leading to the unique Class II element acquisition that characterizes vespertilionids. While it appears that a small number of TcMariner and piggyBac elements were deposited in the ancestral Miniopterus + vespertilionid genome, these elements are not present in M. natalensis genome at high copy number. Instead, this work indicates that the vesper bats alone experienced the expansion of TEs ranging from Helitrons to piggyBacs to hATs.Electronic supplementary materialThe online version of this article (doi:10.1186/s13100-016-0071-y) contains supplementary material, which is available to authorized users.

Evolutionary origin of Rosaceae-specific active non-autonomous hAT elements and their contribution to gene regulation and genomic structural variation.

Transposable elements account for approximately 30 % of the Prunus genome; however, their evolutionary origin and functionality remain largely unclear. In this study, we identified a hAT transposon family, termed Moshan, in Prunus. The Moshan elements consist of three types, aMoshan, tMoshan, and mMoshan. The aMoshan and tMoshan types contain intact or truncated transposase genes, respectively, while the mMoshan type is miniature inverted-repeat transposable element (MITE). The Moshan transposons are unique to Rosaceae, and the copy numbers of different Moshan types are significantly correlated. Sequence homology analysis reveals that the mMoshan MITEs are direct deletion derivatives of the tMoshan progenitors, and one kind of mMoshan containing a MuDR-derived fragment were amplified predominately in the peach genome. The mMoshan sequences contain cis-regulatory elements that can enhance gene expression up to 100-fold. The mMoshan MITEs can serve as potential sources of micro and long noncoding RNAs. Whole-genome re-sequencing analysis indicates that mMoshan elements are highly active, and an insertion into S-haplotype-specific F-box gene was reported to cause the breakdown of self-incompatibility in sour cherry. Taken together, all these results suggest that the mMoshan elements play important roles in regulating gene expression and driving genomic structural variation in Prunus.

Identification, characterization and diversification of non-autonomous hAT transposons and unknown insertions in Brassica

Transposons, the mobile genetics elements played an important role in genome evolution and duplication. Several DNA transposons superfamilies are described in plants and animal genomes; CACTA, hAT, Mariner Mutator and Harbinger being the most diverse among plants. The hAT transposons are proliferating in many plant and animal species. The dot plot comparison, computational and molecular approaches were used for the characterization and diversification of non-autonomous hAT families in Brassica and 494 and 30 full length elements were collected with estimated copies of ~5052 and ~4110 from whole Brassica rapa and Brassica oleracea genomes respectively. The analysis of terminal inverted repeats (TIRs) of these hAT sequences classified them into 13 families on the basis of TIRs sequence similarities. The WebLogo of TIRs of hATs confirmed that few family based TIRs are highly conserved, while other showed variable nucleotide sequences. Transposons based sequence specific amplification polymorphism markers revealed the insertion preference of hATs in diverse Brassica genomes and found many elements as polymorphic across Brassica accessions. Some elements were A or C-genome specific, while most of them are present in Brassica diploids and allopolyploids revealing their presence before separation of A, B and C-Brassica genomes around 8 MYA. Several other unknown mobile insertions were identified with or without TIRs and TSDs of varied lengths, not common to known transposon superfamilies. The detailed study of these insertions revealed their distribution and mobile nature, which although less in numbers and small in sizes are playing a role in genome evolution.

HAT Transposable Elements.

hAT transposons are ancient in their origin and they are widespread across eukaryote kingdoms. They can be present in large numbers in many genomes. However, only a few active forms of these elements have so far been discovered indicating that, like all transposable elements, there is selective pressure to inactivate them. Nonetheless, there have been sufficient numbers of active hAT elements and their transposases characterized that permit an analysis of their structure and function. This review analyzes these and provides a comparison with the several domesticated hAT genes discovered in eukaryote genomes. Active hAT transposons have also been developed as genetic tools and understanding how these may be optimally utilized in new hosts will depend, in part, on understanding the basis of their function in genomes.

The diversification and activity of hAT transposons in Musa genomes.

Sequencing of plant genomes often identified the hAT superfamily as the largest group of DNA transposons. Nevertheless, detailed information on the diversity, abundance and chromosomal localization of plant hAT families are rare. By in silico analyses of the reference genome assembly and bacterial artificial chromosome (BAC) sequences, respectively, we performed the classification and molecular characterization of hAT transposon families in Musa acuminata. Musa hAT transposons are organized in three families designatedMuhAT I, MuhAT II and MuhAT III. In total, 70 complete autonomous elements of the MuhAT I and MuhAT II families were detected, while no autonomous MuhAT III transposons were found. Based on the terminal inverted repeat (TIR)-specific sequence information of the autonomous transposons, 1722 MuhAT I- and MuhAT II-specific miniature inverted-repeat transposable elements (MuhMITEs) were identified. Autonomous MuhAT I and MuhAT II elements areonly moderately abundant in the sections of the genus Musa, while the corresponding MITEs exhibit an amplification in Musa genomes. By fluorescent in situ hybridization(FISH), autonomous MuhAT transposons as well as MuhMITEs were localized in subtelomeric, most likely gene-rich regions of M. acuminata chromosomes. A comparison of homoeologous regions of M. acuminata and Musa balbisiana BACs revealed the species-specific mobility of MuhMITEs. In particular, the activity of MuhMITEs II showing transduplications of genomic sequences might indicate the presence of active MuhAT transposons, thus suggesting a potential role of MuhMITEs as modulators of genome evolution of Musa.

Structural Basis of hAT Transposon End Recognition by Hermes, an Octameric DNA Transposase from Musca domestica

Hermes is a member of the hAT transposon superfamily that has active representatives, including McClintock's archetypal Ac mobile genetic element, in many eukaryotic species. The crystal structure of the Hermes transposase-DNA complex reveals that Hermes forms an octameric ring organized as a tetramer of dimers. Although isolated dimers are active in vitro for all the chemical steps of transposition, only octamers are active in vivo. The octamer can provide not only multiple specific DNA-binding domains to recognize repeated subterminal sequences within the transposon ends, which are important for activity, but also multiple nonspecific DNA binding surfaces for target capture. The unusual assembly explains the basis of bipartite DNA recognition at hAT transposon ends, provides a rationale for transposon end asymmetry, and suggests how the avidity provided by multiple sites of interaction could allow a transposase to locate its transposon ends amidst a sea of chromosomal DNA.

Investigation of hAT and piggyBac transposons in mouse-eared bats (Genus:Myotis)

Abstract. Transposable elements, mobile DNA sequences present in virtually all organisms, have previously been thought to be inactive in mammals. However, current studies have revealed the first evidence of recent piggyBac and hAT activity in Myotis lucifugus. The objective of this study was to further characterize the abundance and diversity of five transposable elements in various Myotis bats. The five elements were confirmed present in 10 species (M. ciliolabrum, M. californicus, M. velifer, M. yumanesis, M. lucifugus, M. thysanodes, M. volans, M. austroriparius, and M. keaysi) spanning the new world clade of Myotis using PCR. Preliminary sequence data focusing on the transposase region was collected and analyzed for two of the elements; hAT3 data set contained 1200 bp and piggyBac1 contained 942 bp. The older hAT3 element had a mean sequence diversity of 1.88%; whereas the younger piggyBac1 element had little diversity (0.01%). A small number of polymorphic sites within the sequence of a single indivi...

BuT2 is a member of the third major group of hAT transposons and is involved in horizontal transfer events in the genus Drosophila.

The hAT superfamily comprises a large and diverse array of DNA transposons found in all supergroups of eukaryotes. Here we characterized the Drosophila buzzatii BuT2 element and found that it harbors a five-exon gene encoding a 643-aa putatively functional transposase. A phylogeny built with 85 hAT transposases yielded, in addition to the two major groups already described, Ac and Buster, a third one comprising 20 sequences that includes BuT2, Tip100, hAT-4_BM, and RP-hAT1. This third group is here named Tip. In addition, we studied the phylogenetic distribution and evolution of BuT2 by in silico searches and molecular approaches. Our data revealed BuT2 was, most often, vertically transmitted during the evolution of genus Drosophila being lost independently in several species. Nevertheless, we propose the occurrence of three horizontal transfer events to explain its distribution and conservation among species. Another aspect of BuT2 evolution and life cycle is the presence of short related sequences, which contain similar 5′ and 3′ regions, including the terminal inverted repeats. These sequences that can be considered as miniature inverted repeat transposable elements probably originated by internal deletion of complete copies and show evidences of recent mobilization.

The goldfish hAT-family transposon Tgf2 is capable of autonomous excision in zebrafish embryos

The goldfish (Carassius auratus) Tgf2 transposon is a vertebrate DNA transposon that belongs to the hAT transposon family. In this study, we constructed plasmids containing either the full-length Tgf2 transposon (pTgf2 plasmid) or a partially-deleted Tgf2 transposon (ΔpTgf2 plasmid), and microinjected these plasmids into fertilized zebrafish (Danio rerio) eggs at the one- to two-cell stage. DNA extracted from the embryos was analyzed by PCR to assess transient excision, if any, of the exogenous plasmid and to verify whether Tgf2 is an autonomous transposon. The results showed that excision-specific bands were not detected in embryos injected with the ΔpTgf2 plasmid, while bands of 300–500bp were detected in embryos injected with pTgf2, which indicated that the full-length Tgf2-containing plasmid could undergo autonomous excision in zebrafish embryos. DNA cloned from 24 embryos injected with pTgf2 was sequenced, and the results suggested that Tgf2 underwent self-excision in zebrafish embryos. Cloning and PCR analysis of DNA extracted from embryos co-injected with ΔpTgf2 and in vitro-transcribed transposase mRNA indicated that partially-deleted-Tgf2-containing ΔpTgf2 plasmid also underwent excision, in the presence of functional transposase mRNA. DNA cloned from 25 embryos co-injected with ΔpTgf2 and transposase mRNA was sequenced, and the results suggested that partially-deleted Tgf2 transposons plasmids were excised. These results demonstrated that excisions of Tgf2 transposons were mediated by the Tgf2 transposase, which in turn confirmed that Tgf2 is an autonomous transposon.

Transposable Elements in Fish Chromosomes: A Study in the Marine Cobia Species

Rachycentron canadum, a unique representative of the Rachycentridae family, has been the subject of considerable biotechnological interest due to its potential use in marine fish farming. This species has undergone extensive research concerning the location of genes and multigene families on its chromosomes. Although most of the genome of some organisms is composed of repeated DNA sequences, aspects of the origin and dispersion of these elements are still largely unknown. The physical mapping of repetitive sequences on the chromosomes of R. canadum proved to be relevant for evolutionary and applied purposes. Therefore, here, we present the mapping by fluorescence in situ hybridization of the transposable element (TE) Tol2, the non-LTR retrotransposons Rex1 and Rex3, together with the 18S and 5S rRNA genes in the chromosome of this species. The Tol2 TE, belonging to the family of hAT transposons, is homogeneously distributed in the euchromatic regions of the chromosomes but with huge colocalization with the 18S rDNA sites. The hybridization signals for Rex1 and Rex3 revealed a semi-arbitrary distribution pattern, presenting differentiated dispersion in euchromatic and heterochromatic regions. Rex1 elements are associated preferentially in heterochromatic regions, while Rex3 shows a scarce distribution in the euchromatic regions of the chromosomes. The colocalization of TEs with 18S and 5S rDNA revealed complex chromosomal regions of repetitive sequences. In addition, the nonpreferential distribution of Rex1 and Rex3 in all heterochromatic regions, as well as the preferential distribution of the Tol2 transposon associated with 18S rDNA sequences, reveals a distinct pattern of organization of TEs in the genome of this species. A heterogeneous chromosomal colonization of TEs may confer different evolutionary rates to the heterochromatic regions of this species.

A Superfamily of DNA Transposons Targeting Multicopy Small RNA Genes

Target-specific integration of transposable elements for multicopy genes, such as ribosomal RNA and small nuclear RNA (snRNA) genes, is of great interest because of the relatively harmless nature, stable inheritance and possible application for targeted gene delivery of target-specific transposable elements. To date, such strict target specificity has been observed only among non-LTR retrotransposons. We here report a new superfamily of sequence-specific DNA transposons, designated Dada. Dada encodes a DDE-type transposase that shows a distant similarity to transposases encoded by eukaryotic MuDR, hAT, P and Kolobok transposons, as well as the prokaryotic IS256 insertion element. Dada generates 6–7 bp target site duplications upon insertion. One family of Dada DNA transposons targets a specific site inside the U6 snRNA genes and are found in various fish species, water flea, oyster and polycheate worm. Other target sequences of the Dada transposons are U1 snRNA genes and different tRNA genes. The targets are well conserved in multicopy genes, indicating that copy number and sequence conservation are the primary constraints on the target choice of Dada transposons. Dada also opens a new frontier for target-specific gene delivery application.

Comparative Analysis of the Recently Discovered hAT Transposon TcBuster in Human Cells

BackgroundTransposons are useful tools for creating transgenic organisms, insertional mutagenesis, and genome engineering. TcBuster, a novel hAT-family transposon system derived from the red flour beetle Tribolium castaneum, was shown to be highly active in previous studies in insect embryoes.Methodology/Principal FindingsWe tested TcBuster for its activity in human embryonic kidney 293 (HEK-293) cells. Excision footprints obtained from HEK-293 cells contained small insertions and deletions consistent with a hAT-type repair mechanism of hairpin formation and non-homologous end-joining. Genome-wide analysis of 23,417 piggyBac, 30,303 Sleeping Beauty, and 27,985 TcBuster integrations in HEK-293 cells revealed a uniquely different integration pattern when compared to other transposon systems with regards to genomic elements. TcBuster experimental conditions were optimized to assay TcBuster activity in HEK-293 cells by colony assay selection for a neomycin-containing transposon. Increasing transposon plasmid increased the number of colonies, whereas gene transfer activity dependent on codon-optimized transposase plasmid peaked at 100 ng with decreased colonies at the highest doses of transposase DNA. Expression of the related human proteins Buster1, Buster3, and SCAND3 in HEK-293 cells did not result in genomic integration of the TcBuster transposon. TcBuster, Tol2, and piggyBac were compared directly at different ratios of transposon to transposase and found to be approximately comparable while having their own ratio preferences.Conclusions/Significance TcBuster was found to be highly active in mammalian HEK-293 cells and represents a promising tool for mammalian genome engineering.

General survey of hAT transposon superfamily with highlight on hobo element in Drosophila

The hAT transposons, very abundant in all kingdoms, have a common evolutionary origin probably predating the plant-fungi-animal divergence. In this paper we present their general characteristics. Members of this superfamily belong to Class II transposable elements. hAT elements share transposase, short terminal inverted repeats and eight base-pairs duplication of genomic target. We focus on hAT elements in Drosophila, especially hobo. Its distribution, dynamics and impact on genome restructuring in laboratory strains as well as in natural populations are reported. Finally, the evolutionary history of hAT elements, their domestication and use as transgenic tools are discussed.

Mar, a MITE family of hAT transposons in Drosophila

BackgroundMiniature inverted-repeat transposable elements (MITEs) are short, nonautonomous DNA elements flanked by subterminal or terminal inverted repeats (TIRs) with no coding capacity. MITEs were originally recognized as important components of plant genomes, where they can attain extremely high copy numbers, and are also found in several animal genomes, including mosquitoes, fish and humans. So far, few MITEs have been described in Drosophila.ResultsHerein we describe the distribution and evolution of Mar, a MITE family of hAT transposons, in Drosophilidae species. In silico searches and PCR screening showed that Mar distribution is restricted to the willistoni subgroup of the Drosophila species, and a phylogenetic analysis of Mar indicates that this element may have originated prior to the diversification of these species. Most of the Mar copies in D. willistoni present conserved target site duplications and TIRs, indicating recent mobilization of these sequences. We also identified relic copies of potentially full-length Mar transposon in D. tropicalis and D. willistoni. The phylogenetic relationship among transposases from the putative full-length Mar and other hAT superfamily elements revealed that Mar is placed into the recently determined Buster group of hAT transposons.ConclusionOn the basis of the obtained data, we can suggest that the origin of these Mar MITEs occurred before the subgroup willistoni speciation, which started about 5.7 Mya. The Mar relic transposase existence indicates that these MITEs originated by internal deletions and suggests that the full-length transposon was recently functional in D. willistoni, promoting Mar MITEs mobilization.