Figure 3.—

Chromosomal in situ analysis in D. virilis (A–C) and D. pseudoobscura (D and E). DvDbp80 and DvRpL15 are on different elements and in different chromosomal contexts. DvDbp80 is in euchromatin on chromosome 3, determined by polytene banding (A), while DvRpL15 appears to be located in the heterochromatic chromocenter (B). Specifically, DvRpL15 is located on chromosome 2, determined from the bright centromere staining in the mitotic spreads (C) and from rare polytene preparations in which chromosome 2 was pulled away from the chromocenter (data not shown). Note from the mitotic spreads (C) that RpL15 (red signal) appears to be located in distal heterochromatin, possibly near the heterochromatic/euchromatic border. This image also suggests how extensive heterochromatin is in the D.virilis genome, occupying fully half the mitotic chromosome length. The two genes are adjacent in D. pseudoobscura, located in the middle of chromosome 2 in this species (D and E).