Molecular characteristics of the heterochromatic I elements from a reactive strain of Drosophila melanogaster.
There are two categories of strains in Drosophila melanogaster with respect to the I-R system of hybrid dysgenesis. The inducer strains contain particular transposable elements named I factors. They are not present in the strains of the other category called reactive (R) strains. Defective I elements are present in the pericentromeric regions of both categories of strains. This last subfamily of I sequences has not yet been described in detail and little is known about its origin. In this paper, we report that the defective I elements display an average of 94% of sequence identity with each other and with the transposable I factor. The results suggest that they cannot be the progenitors of the present day I factors, but that each of these two subfamilies started to evolve independently several million years ago. Furthermore, the sequence comparison of these I elements with an active I factor from Drosophila teissieri provides useful information about when the deleted I elements became immobilized.
Vaury
C
C
Laboratoire de Génétique, Université Blaise Pascal, Aubière, France.
Abad
P
P
Pelisson
A
A
Lenoir
A
A
Bucheton
A
A
D000818:Animals; D001483:Base Sequence; D005075:Biological Evolution; D004251:DNA Transposable Elements; D004331:Drosophila melanogaster / Q000235:genetics*; D006570:Heterochromatin / Q000737:chemistry*; D008969:Molecular Sequence Data; D009154:Mutation; D015183:Restriction Mapping; D012689:Sequence Homology, Nucleic Acid
D004251:DNA Transposable Elements; D006570:Heterochromatin