title: Evolution of the LINE-like I element in the Drosophila melanogaster species subgroup.
abstract: LINE-like retrotransposons, the so-called I elements, control the system of I-R (inducer-reactive) hybrid dysgenesis in Drosophila melanogaster. I elements are present in many Drosophila species. It has been suggested that active, complete I elements, located at different sites on the chromosomes, invaded natural populations of D. melanogaster recently (1920-1970). But old strains lacking active I elements have only defective I elements located in the chromocenter. We have cloned I elements from D. melanogaster and the melanogaster subgroup. In D. melanogaster, the nucleotide sequences of chromocentral I elements differed from those on chromosome arms by as much as 7%. All the I elements of D. mauritiana and D. sechellia are more closely related to the chromosomal I elements of D. melanogaster than to the chromocentral I elements in any species. No sequence difference was observed in the surveyed region between two chromosomal I elements isolated from D. melanogaster and one from D. simulans. These findings strongly support the idea that the defective chromocentral I elements of D. melanogaster originated before the species diverged and the chromosomal I elements were eliminated. The chromosomal I elements reinvaded natural populations of D. melanogaster recently, and were possibly introduced from D. simulans by horizontal transmission.
authors.affiliation: Department of Molecular Biology, Graduate School of Medical Science, Kyushu University, Fukuoka, Japan.
authors.forename: H
authors.initials: H
authors.lastname: Sezutsu
authors.forename: E
authors.initials: E
authors.lastname: Nitasaka
authors.forename: T
authors.initials: T
authors.lastname: Yamazaki
mesh_terms: D000818:Animals; D001483:Base Sequence; D005075:Biological Evolution; D002874:Chromosome Mapping; D003001:Cloning, Molecular; D016384:Consensus Sequence; D004330:Drosophila / Q000145:classification / Q000235:genetics*; D004331:Drosophila melanogaster / Q000145:classification / Q000235:genetics*; D017403:In Situ Hybridization; D008969:Molecular Sequence Data; D010802:Phylogeny; D015183:Restriction Mapping; D018626:Retroelements
chemical_list: D018626:Retroelements