Natural Transposon: Dmel\412
Natural Transposon: Dmel\412
481 or 571 (FBrf0036946)
31 in euchromatin of Release 3 genome annotation, of which 24 are full length.
TE copies retrieved from release 5.1 of the D. melanogaster genome.:36
Expression is enriched in embryonic gonads.
The expression of 412 varies greatly between populations.
Transposable elements can be used to reveal cross-over events.
No transposition was detected in progeny after heat shock of parents.
Correlations between the rate of transposition and TE copy number are determined for 412 and roo and are found to be zero.
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.
Functional site motifs are distributed within the 412 element.
Analysis of motifs of functional sites reveals these motifs ensure the basic molecular functions of 412, expression of its open reading frame, transcription, induction of transposition and modification of adjacent genes and polygenes.
412 is expressed in a cell-specific manner during embryogenesis. At stage 11 transcripts are present in bilateral clusters of cells within the mesoderm. The posterior clusters of cells become associated with the gonads at stage 13. Results demonstrate development of the visceral muscle or fat body do not affect the expression of 412 during embryogenesis.
Spontaneous insertions and excisions of mdg1, copia, 412 and roo have been monitored over 65 generations of mass mating. Excisions are outnumbered by insertions. Their contribution to variation for transposable element location is not great.
The distribution of transposable elements in D.simulans is similar to that found in D.melanogaster, though total copy number is lower.
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 during embryogenesis suggest that all families carry cis-acting elements that control their spatial and temporal expression patterns.
The copia and 412 transposable elements increase in copy number in aged adult tissue due to the activation of reverse transcriptase.
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.
Polymorphism of transposable elements in inbred lines has been examined: P-element, gypsy, jockey, I-element, mdg1, 412, mdg3 and 297 sites are largely stable, whereas roo and copia sites are polymorphic.
Expression of the 412 element provides a useful early marker for the development of the gonadal mesoderm. This high level of expression does not depend on contact with germ cells, but does depend on abd-A and Abd-B.
During the course of experiments with genetically unstable MS strains gypsy elements were observed to transpose whereas mdg1 and 412 sites in the X chromosome were unchanged.
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.
Increase in transposition of 412 by heavy heat shock treatment is statistically significant.
Multiple transpositions of copia-like 412 occur in the next generation after heat shock treatment.
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.
the 5' LTR contains an additional 33bp of which 29 are a direct repeat of the LTR sequence, there is a 3bp insertion between ft and the 5' LTR, 11bp of ft DNA at site of insertion is lost.
The mdg1 element shows considerable homology with the 412 element.
Transposition rates of mobile elements in lines AW and JH, in which spontaneous mutations have accumulated for about 400 generations, are studied. 412 and 17.6 elements rate of transposition is very low, I-element and hobo insertions occur much more frequently.
The distribution of a number of transposable elements, including 412 elements, in a D.melanogaster laboratory strain with a high frequency of spontaneous mutations and its derivatives, has been studied.
The genomic distribution of transposable elements in somatic tissues and during development is homogeneous.