Variability in the molecular organization of the 5S RNA genes among strains of Drosophila melanogaster.

The organization of the 5S RNA cluster has been analyzed in four strains of Drosophila melanogaster by the Southern technique. In some of the strains the 5S RNA cluster appears to be interrupted by an unrelated sequence. In other strains a continuous cluster is present

Revising the selfish DNA hypothesis: new evidence on accumulation of transposable elements in heterochromatin.

The bulk of the eukaryotic genome is composed of families of repetitive sequences that are genetically silent and exhibit various types of instability. Transposable elements (TEs) are particularly commmon in heterochromatic regions of the genome – a location where TEs might do less damage to their host. Recent advances suggest that the relationship between TEs and heterochromatin might not be quite so straightforward

Colonization of heterochromatic genes by transposable elements in Drosophila.

As a further step toward understanding transposable element–host genome interactions, we investigated the molecular anatomy of introns from five heterochromatic and 22 euchromatic protein-coding genes of Drosophila melanogaster. A total of 79 kb of intronic sequences from heterochromatic genes and 355 kb of intronic sequences from euchromatic genes have been used in Blast searches against Drosophila transposable elements (TEs). The results show that TE-homologous sequences belonging to 19 different families represent about 50% of intronic DNA from heterochromatic genes. In contrast, only 0.1% of the euchromatic intron DNA exhibits homology to known TEs. Intraspecific and interspecific size polymorphisms of introns were found, which are likely to be associated with changes in TE-related sequences. Together, the enrichment in TEs and the apparent dynamic state of heterochromatic introns suggest that TEs contribute significantly to the evolution of genes located in heterochromatin

Colonization of heterochromatic genes by transposable elements in Drosophila melanogaster.

As a further step toward understanding transposable element–host genome interactions, we investigated the molecular anatomy of introns from five heterochromatic and 22 euchromatic protein-coding genes of Drosophila melanogaster. A total of 79 kb of intronic sequences from heterochromatic genes and 355 kb of intronic sequences from euchromatic genes have been used in Blast searches against Drosophila transposable elements (TEs). The results show that TEhomologous sequences belonging to 19 different families represent about 50% of intronic DNA from heterochromatic genes. In contrast, only 0.1% of the euchromatic intron DNA exhibits homology to known TEs. Intraspecific and interspecific size polymorphisms of introns were found, which are likely to be associated with changes in TE-related sequences. Together, the enrichment in TEs and the apparent dynamic state of heterochromatic introns suggest that TEs contribute significantly to the evolution of genes located in heterochromatin