Genomic distribution of copia-like elements in laboratory stocks of Drosophila melanogaster

Structure and function of repetitive DNA in eukaryotes

“…Using a panel of seventeen dispersed middle-repetitive DNA sequences selected at random by cloning, Young (1979) showed that the locations of some or all of the sequences differed in the polytene chromosomes of two non-interbreeding strains of Drosophila melanogaster, indicating that in all cases the sequences were derived from families of mobile genetic elements. Similar experiments have been performed in several other laboratories Ananiev et al, 1984;Hunt et al, 1984;Junakovic et al, 1984). Some of these sequences correspond to well-characterized families of transposable genetic elements, including Copia-like sequences (Copia, 412, 297, 17.6, mdgl, mdg3, B104;Rubin et al, 1981;Scherer et al, 1982) and other distinct families ofmobile elements including FB elements (Potter et al, 1980), Gypsy (Modolell et al, 1983), P-elements (Rubin etal., 1982), hobo (McGinnis etal., 1983), I-factors (Bucheton et al, 1984) and less well-characterized mobile elements (Young, 1979).…”

“…It has been estimated that these families of dispersed transposable genetic elements collectively may total over 30 and account for most of the remaining 75% of the middle-repetitive DNA in Drosophila melanogaster and related species (Spradling & Rubin, 1981). The locations of these dispersed mobile elements are generally conserved within an inbred fly population (Ananiev et al, 1984) and variant between separate stocks of the same species (Young, 1979;Junakovic et al, 1984). Moreover, some families of transposable elements may be absent altogether from closely related species of Drosophila (Dowsett & Young, 1982;Hunt et al, 1984).…”

Copy-number dependent transpositions and excisions of the mdg-1 mobile element in inbred lines of Drosophila melanogaster

“…The transposition rate is estimated to be around io; higher values are observed only in the offspring of matings between certain strains of Drosophila melanogaster (the hybrid dysgenesis phenomenon: Engels and Preston, 1981;Thompson and Woodruff, 1981;Bingham et al, 1982;Brégliano and Kidwell, 1983;Gerasimova et al, 1984). We also have evidence against a high rate of transposition under "normal conditions" (Young and Schwartz, 1981;Pierce and Lucchesi, 1981) and against a generally high mutation rate on highly homozygous lines (Woodruff et a!., 1984;Junakovic et aL, 1984). However, highly inbred populations of Drosophila may show genome reshuffling when submitted to mass matings (Belyaeva et a!., 1982) and inbred lines of maize may have unstable mutations produced by the Mu transposable element (Strommer, 1983).…”

Homologous sequences to the P transposable element in Drosophila subobscura

“…Drosophila genomic DNAs were extracted following the method described by Junakovic et al (1984). Nick translated probes labeled with 32 P were hybridized to the genomic DNAs from D subobscura by squash blotting (an especial dot blot designed by Tchen et al, 1985) and Southern blotting (Southern, 1975).…”