title: A rapid decrease in number of the complete ninja element and concomitant increase of the defective element in a strain of Drosophila simulans.
abstract: The ninja element, originally isolated from an unstable white mutant strain white-milky (w(mky)) of Drosophila simulans, is a member of the retrotransposon family with long terminal repeats (LTRs). We show that ninja is present in high copy numbers in the w(mky)-derivative sublines white-chocolate (w(cho)) and white-persimmonl (w(psm1)), in a low copy number in another derivative subline white-milky 3 (w(mky3)), and in only a few copies in a wild type strain. We have cloned the ninja elements from these sublines and examined their structures. Most of the elements cloned (38 out of 41 independent clones) from w(cho) were full length. In contrast, only 9 of 23 independent clones from w(mky3) were full length. We hypothesize that ninja elements were integrated and lost frequently in the w(mky) strain and its derivative genomes, and that a rapid decrease in numbers of the ninja element was caused not by an increased rate of loss but by a reduction of integration of full length ninja elements in w(mky3). Each defective element had a unique deletion and/or an insertion except for the three from w(mky3), which had exactly the same 81-bp deletion in each of the 5' and 3' LTRs. The 5' and 3' ends of the deletion appeared to represent sequences similar to those of Drosophila consensussplicing sites. Ectopic splicing may have produced these defective ninja elements.
authors: Drosophila Genetic Resource Center, Kyoto Institute of Technology, Saga Ippongi-cho, Ukyo-ku, Kyoto, 616-8354, Japan.
authors: Keiji
authors: K
authors: Ogura
authors: Takashi
authors: T
authors: Ohsako
authors: Masa-Toshi
authors: MT
authors: Yamamoto
mesh_terms: D000818:Animals; D001483:Base Sequence; D003001:Cloning, Molecular; D004268:DNA-Binding Proteins / Q000235:genetics*; D004330:Drosophila / Q000235:genetics*; D029721:Drosophila Proteins / Q000235:genetics*; D019143:Evolution, Molecular; D008969:Molecular Sequence Data; D009154:Mutation; D010858:Pigmentation / Q000235:genetics; D018626:Retroelements; D020079:Terminal Repeat Sequences
chemical_list: D004268:DNA-Binding Proteins; D029721:Drosophila Proteins; D018626:Retroelements; C101578:ninja-pol protein, Drosophila