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 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.
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.
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.
Studies of mdg3 copy number in a number of different strains suggests the existence of a genomic mechanism for the maintenance of retrotransposon copy number at a particular level.
The distribution of a number of transposable elements, including mdg3 elements, in a D.melanogaster laboratory strain with a high frequency of spontaneous mutations and its derivatives, has been studied.
The long terminal repeats (LTRs) and adjacent regions of the mdg3 element have been sequenced. The mdg3 element is flanked by a 5bp inverted repeat, and a 4bp duplication of the host DNA is generated on integration of the element. The length of the LTR varies in different mdg3 elements, the most common elements having an LTR of 267bp.
An insertion of P{SUPor-P} into an mdg3 has been identified by virtue of decreasing transmission of Dp(1;f)J21A to offspring to 10%.
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 mdg3 elements in heterochromatin has been studied by in situ hybridisation to mitotic chromosomes.
The distribution of a number of transposable elements has been studied in 10 Harwich mutation accumulation lines.
The distribution of mdg3 elements across the chromosomes has been analysed in individuals from a natural population of D.melanogaster.
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 mdg3 element have been determined.
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.
Numbers of mdg1, mdg3, gypsy and copia have been studied in several strains of D.melanogaster and D.simulans. Mean number of mdg1 and copia sites are drastically reduced in D.simulans. Majority of mdg1 and copia sites, and one third of mdg3 sites, are in hot spots for insertion, particularly in D.simulans. Southern blot analysis indicates that the majority of mdg1 and copia are in the euchromatin of D.melanogaster but the heterochromatin of D.simulans.
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.
Studies of mdg3 copy number in a number of different strains suggests the existence of a genomic mechanism for the maintenance of retrotransposon copy number at a particular level.
The distribution of a number of transposable elements, including mdg3 elements, in a D.melanogaster laboratory strain with a high frequency of spontaneous mutations and its derivatives, has been studied.
The long terminal repeats (LTRs) and adjacent regions of the mdg3 element have been sequenced. The mdg3 element is flanked by a 5bp inverted repeat, and a 4bp duplication of the host DNA is generated on integration of the element. The length of the LTR varies in different mdg3 elements, the most common elements having an LTR of 267bp.