Abstract
We analyzed the distribution of the Bari-I transposable element in Drosophila melanogaster (IN(1)AB), its sibling species Drosophila simulans (C167.4) and in eight hybrid strains derived from initial crosses involving D. simulans females and D. melanogaster males of the above cited strains as well as in Brazilian populations of these species. Polymerase chain reaction (PCR) data showed the presence of the Bari-I element among species populations and hybrid strains. Hybridization with a 703 bp probe homologous to the Bari-I sequence showed that the number of Bari-I copies in D. melanogaster IN(1)AB was higher than in D. simulans C167.4 strains. Hybrid strains presented Bari-I sequences related to both parental species. In addition some strains displayed a Bari-I sequence that came from D. melanogaster, suggesting introgression of D. melanogaster genetic material in the background of D. simulans. In contrast, some hybrids showed deletions of D. simulans Bari-I sequences.
Highlights
The Bari-I element, initially found in Drosophila melanogaster, is a Class II transposable element with an open reading frame (ORF) able to encode for a polypeptide with 339 amino acids
These results are in agreement with those obtained by Caggese et al (1995) regarding the distribution of the Bari-I element transposable in D. melanogaster and D. simulans
Besides bands that were present in the parental D. simulans and D. melanogaster strains, the hybrid strain SM2 displayed a band originally not found in either of the parent strains, while strains SM3 and SM4 showed a band originally found in D. melanogaster but not in D. simulans
Summary
The Bari-I element, initially found in Drosophila melanogaster, is a Class II transposable element with an open reading frame (ORF) able to encode for a polypeptide with 339 amino acids. The amino acids sequence of the putative protein in Bari-I is similar to the transposase of the Tc-1 element of Caernorhabditis elegans (Rosenzweig et al, 1983). While many heterochromatic elements exhibit rearrangements that result in a loss of coding capacity (O’Hare and Rubin, 1983; Di Nocera et al, 1986; Streck et al, 1986; Vaury et al, 1989; Crozatier et al, 1988;) the Bari-I element presents heterochromatic and euchromatic copies with very similar ORFs in structure and sequence. Studies regarding variability in the distribution of the Bari-I element conducted by Caggese et al (1995) showed that this element occurs in D. melanogaster and Drosophila simulans populations. Differences occur in the distribution patterns of the Bari-I element between these two sibling Drosophila species, the main differences being that D. melanogaster contains heterochromatic groups of the Bari-I element arranged in tandem on the second chromosome whereas in D. simulans there are just a few diffuse copies of this element spread throughout the genome
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