Figure 3.

Hybridization of TART^vir and TART^ame to the telomeres in polytene chromosomes. (a) D. virilis. Three telomeres from the same nucleus are shown. Each has probe hybridized to the terminal region (arrows). Note that this region is aggregated into four balls on one telomere (shown enlarged in Inset). There is no hybridization over any banded chromosome regions. (b) The free telomere of D. americana that hybridizes with TART^ame. As in D. virilis, there is no hybridization in any banded chromosome regions. (c) Chromocenter from a polytene nucleus of D. americana; two discrete regions of the heterochromatic chromocenter are labeled (arrows). [Hybridized probe detected by alkaline phosphatase activity (7). See Materials and Methods for probes.]