Transposable elements are stable structural components of Drosophila melanogaster heterochromatin.

Abstract

We determined the distribution of 11 different transposable elements on Drosophila melanogaster mitotic chromosomes by using high-resolution fluorescent in situ hybridization (FISH) coupled with charge-coupled device camera analysis. Nine of these transposable elements (copia, gypsy, mdg-1, blood, Doc, I, F, G, and Bari-]) are preferentially clustered into one or more discrete heterochromatic regions in chromosomes of the Oregon-R laboratory stoclk Moreover, FISH analysis of geographically distant strains revealed that the locations of these heterochromatic transposable element clusters are highly conserved. The P and hobo elements, which are likely to have invaded the D. melanogaster genome at the beginning of this century, are absent from Oregon-R heterochromatin but clearly exhibit heterochromatic clusters in certain natural populations. Together these data indicate that transposable elements are major structural components of Drosophila heterochromatin, and they change the current views on the role of transposable elements in host genome evolution.

The Evolutionary History of Drosophila buzzatii. XXXVI. Molecular Structural Analysis of Osvaldo Retrotransposon Insertions in Colonizing Populations Unveils Drift Effects in Founder Events

“…The P1 heterochromatic clone represents a copy of an inactive Osvaldo element that has accumulated many structural changes over time. It is usually thought that heterochromatic copies of retrotransposons represent the end point of an ancient invasion and that heterochromatic regions serve as a sink for ancient, defective copies (Shevelyov et al 1989; Vaury et al 1989; Pimpinelli et al 1995;Dimitri 1997). The clones B4, A4, and B9, are different even though they all are euchromatic.…”

The role of repetitive DNA in structure and evolution of sex chromosomes in plants

“…In general, regions with suppressed or no recombination tend to accumulate repetitive DNA sequences (for review see Charlesworth et al, 1994;Gvozdev et al, 2005). Nonrecombining parts of the Y chromosome have accumulated repetitive DNA, particularly in the mammalian (Erlandsson et al, 2000;Skaletsky et al, 2003) and Drosophila melanogaster (Pimpinelli et al, 1995) Y chromosomes, which are evolutionarily ancient, originating before 165 and 60 mya, respectively (Graves, 2005;Veyrunes et al, 2008). However, the process of accumulation of repetitive sequences is apparent even in evolutionarily young sex chromosomes, such as in Drosophila miranda (Steinemann and Steinemann, 1992), Silene latifolia (Hobza et al, 2006;Kejnovsky et al, 2006a) or Carica papaya (Liu et al, 2004).…”

The Y chromosome as a target for acquired and amplified genetic material in evolution

“…(37) The Y chromosome of D. melanogaster has been shown to be highly populated with retrotransposons of different families. (38) However, their localization here may be interpreted in favor of their beneficial role, taking into account their stability and non-random localization in different parts of heterochromatin. Thus, the concentration of the telomere-specific Het-A retrotransposon in the internal regions of the Drosophila melanogaster Y chromosome remains enigmatic and may be associated with their involvement in telomere maintenance.…”