Abstract
Data of insertion site localization and site occupancy frequency of P, hobo, I, copia, mdg1, mdg3, 412, 297, and roo transposable elements (TEs) on the polytene chromosomes of Drosophila melanogaster were extracted from the literature. We show that TE insertion site number per chromosomal division was significantly correlated with the amount of DNA. The insertion site number weighted by DNA content was not correlated with recombination rate for all TEs except hobo, for which a positive correlation was detected. No global tendency emerged in the relationship between TE site occupancy frequency, weighted by DNA content, and recombination rate; a strong negative correlation was, however, found for the 3L arm. A possible dominant deleterious effect of chromosomal rearrangements due to recombination between TE insertions is thus not the main factor explaining the dynamics of TEs, since this hypothesis implies a negative relationship between recombination rate and both TE insertion site number and site occupancy frequency. The alternative hypothesis of selection against deleterious effects of insertional mutations is discussed.
Overexpression of the SuUR gene induces reversible modifications at pericentric, telomeric and intercalary heterochromatin of Drosophila melanogaster polytene chromosomes
