Natural Transposon: Dmel\297
Natural Transposon: Dmel\297
Approximately 30 (FBrf0032823)
57 in euchromatin of Release 3 genome annotation, of which 18 are full length.
TE copies retrieved from release 5.1 of the D. melanogaster genome.:77
Expression is enriched in embryonic gonads.
Used in an investigation to address the relationship between retrotransposons and retroviruses and the coadaptation of these retroelements to their host genomes. Results indicate retrotransposons are heterogeneous in contrast to retroviruses, suggesting different modes of evolution by slippage-like mechanisms.
Study of TE distribution (P-element, hobo, I-element, copia, mdg1, mdg3, 412, 297 and roo) along chromosome arms shows no global tendency for the TE site occupancy frequency to negatively follow the recombination rate, except for the 3L arm. The tendency for TE insertion number to increase from base to tip of some chromosome arms is simply explicable by a positive relationship with DNA content along the chromosomes. So for all TEs, except hobo, there is no relationship between distribution of TE insertion numbers weighted by DNA content and recombination rate. hobo insertion site number is positively correlated with recombination rate.
The distribution of a number of transposable elements has been studied in 10 Harwich mutation accumulation lines.
The chromosomal distribution of a number of retrotransposons in an isolated population of D.melanogaster (from Ishigaki Island, Okinawa, Japan) has been determined.
Estimating the genomic numbers of transposable elements demonstrates many families of element are over-represented in heterochromatin.
The spatial and temporal expression patterns of fifteen families of retrotransposons are analysed during embryogenesis and are found to be conserved. Results suggest that all families carry cis-acting elements that control their spatial and temporal expression patterns.
Rates of transposition and excision of the 297 element have been determined.
Element copy numbers on inversion and standard chromosomes has been determined. The copy number is significantly higher within low frequency inversions than within the corresponding standard chromosome regions.
Distribution of 9 families of transposable elements in a natural population was studied and the hypothesis that transposable element abundance is regulated primarily by deleterious fitness consequences of ectopic meiotic exchange was supported. Proximal euchromatin may only infrequently undergo exchange, and elements detected in population surveys of this kind tend to be inserted into sites where there is negligible effect on fitness.
One substock of inbred lines shows considerable heterogeneity of insertion sites of copia (frequency of insertions is 12% per haploid genome per generation) whereas mdg1, 412, mdg3, gypsy, 297 and HMS-Beagle were stable in all stocks examined.
Stability of 11 transposable element families compared by Southern blotting among individuals of lines that had been subjected to 30 generations of sister sib matings. 412, roo, blood, 297, 1731 and G-element all appear stable, whereas copia, hobo, I-element, gypsy and jockey elements show instability.
297 elements were first described by Potter et al. (FBrf0032823) but were originally identified by Wensink and Rubin as being complementary to abundant polyA RNA in tissue-culture cells.