Spatially regulated expression of retrovirus-like transposons duringDrosophila melanogasterembryogenesis

Abstract

Over twenty distinct families of long terminal direct repeat (LTR)-containing retrotransposons have been identified in Drosophila melanogaster. While there have been extensive analyses of retrotransposon transcription in cultured cells, there have been few studies of the spatial expression of retrotransposons during normal development. Here we report a detailed analysis of the spatial expression patterns of fifteen families of retrotransposons during Drosophila melanogaster embryogenesis (17.6, 297, 412, 1731, 3S18, blood, copia, gypsy, HMS Beagle, Kermit/flea, mdgl, mdg3, opus, roo/B104 and springer). In each case, analyses were carried out in from two to four wild-type strains. Since the chromosomal insertion sites of any particular family of retrotransposons vary widely among wild-type strains, a spatial expression pattern that is conserved among strains is likely to have been generated through interaction of host transcription factors with cw-regulatory elements resident in the retrotransposons themselves. All fifteen families of retrotransposons showed conserved patterns of spatially and temporally regulated expression during embryogenesis. These results suggest that all families of retrotransposons carry cw-acting elements that control their spatial and temporal expression patterns. Thus, transposition of a retrotransposon into or near a particular host gene -possibly followed by an excision event leaving behind the retrotransposon's cw-regulatory sequences -might impose novel developmental control on such a host gene. Such a mechanism would serve to confer evolutionarily significant alterations in the spatio-temporal control of gene expression.

Molecular characterization of embryonic gonads by gene expression profiling in Drosophila melanogaster

“…3). These observations are in accordance with the previous reports showing that transcripts for 17.6, 412, mdg1, 297, and gypsy accumulate in the EGs (23,24). It is interesting to note that these transcripts were all detected in gonadal somatic cells rather than in pole cells (Fig.…”

High-fidelity promoter profiling reveals widespread alternative promoter usage and transposon-driven developmental gene expression

“…4A). Prompted by previous reports of developmental expression of transposons (Parkhurst and Corces 1987;Ding and Lipshitz 1994;Mozer and Benzer 1994), we established expression profiles for individual subfamilies (Methods). Virtually all transposon subfamilies display clear developmental regulation (Fig.…”

Tissue-specificity of 412 retrotransposon expression in Drosophila simulans and D. melanogaster

“…TE expression patterns during embryogenesis (Ding and Lipshitz, 1994) and during the development of Drosophila (Parkhurst and Corces, 1987) were found to be identical for several TEs, which suggests that cis-regulatory sequences are conserved. In Drosophila, the expression of I, gypsy, and P elements is greater in females than in males (Busseau et al, 1994;Pélisson et al, 1994;Roche et al, 1995), whereas the expression of micropia, 1731 and copia is mainly detected in males (Lankenau et al, 1994;Haoudi et al, 1997;Pasyukova et al, 1997).…”

“…Spatial and temporal TE expression patterns may also be influenced by host factors, such as developmental genes (Brookman et al, 1992;Frö mmer et al, 1994), modifiers (Birchler and Hiebert, 1989;Rabinow et al, 1993;Birchler et al, 1994;Csink et al, 1994a,b), and hormones (Becker et al, 1991). For example, the embryonic expression of the 412 element results from interactions with the Ultrabithorax, AbdA-B and pox meso developmental genes (Brookman et al, 1992;Ding and Lipshitz, 1994).…”