Structural variations in the Drosophila retrotransposon, 17.6.

More than 21 members of 17.6, a Drosophila retrotransposon, were isolated and their possible structural changes were examined by restriction mapping, blot hybridization, heteroduplex analysis and nucleotide sequence determination of long terminal repeats (LTRs). At least 7 members were found to suffer with terminal or internal long deletions. No pair of LTRs having an identical nucleotide sequence was found either within an element or between elements. Although an initiation site for the presumable genome-sized transcript of 17.6, a potential substrate for reverse transcription on translocation, was identified within the left-hand LTR, our results as a whole support the notion that the majority of 17.6s have continued to reside for a long period of time at their present chromosomal loci and hence the rate of translocation of 17.6 is very low.