A DNA sequence of Drosophila melanogaster with a differential telomeric distribution.

A DNA sequence (8-19T) of 2.3 kilobase pairs (kb) of Drosophila melanogaster was localized by in situ hybridization to the extreme ends of polytene chromosomes and to the chromocenter. The relative abundance of this sequence at the ends of polytene chromosomes X:2L:2R:3L:3R is 1:3.4:1.9:0:2.7. This differential distribution is probably due to different copy numbers at the individual telomeric regions. Restriction enzyme analysis of genomic DNA shows that 8-19T sequences are interspersed with other sequences. The clone 8-19T, which contains most of this interspersed repetitive sequence, is itself not internally repetitive but has a complex sequence composition. Some of these sequences are transcribed into poly(A)+RNA. We suggest that the ends of Drosophila chromosomes are of a complex arrangement with some sequences common to all ends.