Mariner-like elements in hymenopteran species: insertion site and distribution.

Abstract

Copies of mariner-like element (MLE) transposons in two species, the bumble bee, Bombus terrestis, and the ant, Myrmica ruginodis, were sequenced. The hfll-sized elements are 1250 bp long in both species and include 28-bp inverted terminal repeats. The five copies sequenced were -75% similar to a mariner element (peach) of Drosophila maurina. The distribution of MLE in 27 hymenopteran species was studied by PCR and Southern blot hybridization; 93% of the species contained one or more of the four major forms of the element. They are inserted in their host genomes, in the middle ofa degenerated 30-bp palindrome, which is itself located in an 85-bp conserved region with a purine-rich tail at one of Its ends. The genomes of two parasitoid wasps, Diadromus pulchellus and Eupelmus vuilleti (7), and the honey bee, Apis mellifera (8), contain few interspersed repeated sequences corresponding to transposable elements. This might be due to the elimination of deleterious transposable elements in haploid males. However, R1 and R2 Line 1-like retrotransposable elements, which both have a specific insertion site in the 28S rRNA-encoding genes, are present in the 24 hymenopteran species tested to date (9, 10). These elements probably have no deleterious effects on insect viability because of the repeated structure of the 28S rRNA genes and therefore would not be eliminated by male haploidy. This insertion-site specificity may explain why they are found in Hymenoptera.Another transposon, mariner, has recently been shown to be widespread among insect orders (11). The complete copies of mariner-like elements (MLEs) in Drosophila mauritiana (Diptera) (12), Hyalophora cecropia (Lepidoptera) (13), and Chrysoptra plorabunda (Neuroptera) (14)

Diverse DNA transposons in rotifers of the class Bdelloidea

“…5 Top, which is published as supporting information on the PNAS web site). This finding may be interpreted as evidence of Avmar1 insertion preference for a specific target site in a multicopy sequence, which is unusual for DNA TEs, but not unprecedented (19,27). Alternatively, a copy of Avmar1 may have been inserted into another TE with a higher proliferative potential, leading to preferential amplification of this copy within a larger transposable unit.…”

Cloning and characterization of a mariner-like element in the silkworm, Bombyx mori.

“…Mariner-like elements (MLE) are found in many other insects (Robertson et al, 1992;Robertson, 1993;Bigot et al, 1994;Ebert et al, 1995) as well as in other organisms (Robertson and Macleod, 1993;Sedensky et al, 1994;Robertson, 1995), and are suggested to have spread horizontally Kidwell, 1993). Given these characteristics of mariner, it was predicted that the Bombyx mori genome might contain a similar element, and one type of MLE, Bmmar1 was found (Robertson and Asplund, 1996).…”

Human and other mammalian genomes contain transposons of the mariner family

“…Cloning and phage preparations were performed by standard methods [11]. The inserts were sequenced on one strand with Sequenase v2.0 (USB), using denaturing gels either of polyacrylamide in buffer gradients or Hydrolink long ranger gels (AT-Biochem) as described [2]. Alignments of the mammalian MLEs sequences are performed from published data [1] and using CITI2 programs [13].…”

“…MLEs were detected in about 20% of 400 insect species tested for these two motifs by polymerase chain reaction (PCR) using degenerate primers [1]. We previously used PCR, sequencing and the stepping-stone hybridization method to evidence MLEs in all the 40 hymenopteran species tested ( [2] and personnal data). MLEs have also been detected in Nematodes [3], Crustaceae [4] *Corresponding author.…”

“…In eukaryotic genomes, transposable elements moving via a DNA intermediate are called transposons [1][2][3][4][5][6][7]. Many of those described have been studied in invertebrate and plant species [8].…”