Examination of the P-element phylogeny in light of the species phylogeny suggests that additional horizontal transfers may have occurred at various times in the past and may explain the overall structure of the P-element phylogeny in Sophophora.
The stationary P-element related gene clusters of D.guanche, D.madeirensis and D.subobscura provide a model system to study the evolutionary impact of TEs on genome evolution. Each cluster unit consists of a cis-regulatory section composed of different insertion sequences followed by the first three exons of a P-element that is coding for a 66kD 'repressor-like' protein.
A P-element related gene cluster exists at a single gene location. The repeat units consist of a truncated 2kb P-element homologous region with the coding capacity for a 66kD P-repressor-like protein. The 5' and 3' non-coding regions and the third exon have been eroded by random mutations.
Two types of repeat unit (A-type and G-type) are found in the gene clusters of Dgua\P-element and Dsub\P-element. The divergence of these two types can be traced to a common ancestor of the guanche and subobscura species. Transcriptional activity in adults can be demonstrated only for the A-type sequences. The N-terminal section of both active and inactive transposase contain motifs characteristic of DNA-binding domains.
P-element sequences from nine Dipteran species, including D.subobscura, have been compared. The P-element phylogeny contradicts the phylogeny of the species, suggesting that horizontal transfer of P-elements may have occurred.
Examination of the P-element phylogeny in light of the species phylogeny suggests that additional horizontal transfers may have occurred at various times in the past and may explain the overall structure of the P-element phylogeny in Sophophora.
The stationary P-element related gene clusters of D.guanche, D.madeirensis and D.subobscura provide a model system to study the evolutionary impact of TEs on genome evolution. Each cluster unit consists of a cis-regulatory section composed of different insertion sequences followed by the first three exons of a P-element that is coding for a 66kD 'repressor-like' protein.
A phylogenetic survey has identified four major P-element subfamilies in the saltans and willistoni species groups of Drosophila.
A P-element related gene cluster exists at a single gene location. The repeat units consist of a truncated 2kb P-element homologous region with the coding capacity for a 66kD P-repressor-like protein. The 5' and 3' non-coding regions and the third exon have been eroded by random mutations.
Two types of repeat unit (A-type and G-type) are found in the gene clusters of Dgua\P-element and Dsub\P-element. The divergence of these two types can be traced to a common ancestor of the guanche and subobscura species. Transcriptional activity in adults can be demonstrated only for the A-type sequences. The N-terminal section of both active and inactive transposase contain motifs characteristic of DNA-binding domains.
P-element sequences from nine Dipteran species, including D.subobscura, have been compared. The P-element phylogeny contradicts the phylogeny of the species, suggesting that horizontal transfer of P-elements may have occurred.
A heterochromatic Dsub\P-element is the remnant of an ancestral sequence in the subobscura cluster species which has lost its coding capacity.
Dsub\P-element shows close sequence similarity to its D.melanogaster homolog.
A number of Dsub\P-elements have been cloned and sequenced. All of the isolated elements are truncated at the 5' and 3' ends.