FIG. 2.

The EP473 P-element insertion results in down-regulation of D1. (A) Map of the genomic D1 locus. Sequence coordinates are given relative to the start of the D1 mRNA (+1). Exons are represented by black boxes and 5" and 3" untranslated regions are in gray. Restriction enzyme sites shown are those used to characterize the EP473 P-element insertion and excisions thereof. The P-element insertion diagrammed below the map occurs at position −66. The thick line indicates the extent of the transposon bounded by 5" and 3" inverted repeats (IR; divergent filled arrows). (B) Coomassie blue-stained gel loaded with equivalent amounts of total proteins from wild-type, heterozygous, or homozygous EP473 mutant first-instar larvae and from Kc nuclei (lanes 1 to 4, respectively). A duplicate gel was subjected to Western blot analysis as described above (C). The positions of the D1 bands observed in embryos and tissue-culture cells are indicated to the right. (D) In situ hybridizations to D1 mRNA were performed with wild-type (a to c) and homozygous (d to f) EP473 embryos identified as described in Materials and Methods. (E) Wild-type larvae and homozygous EP473 force-hatched first-instar larvae (see text for details) were processed for DNA staining (red) and D1 immunolabeling (green). Merged signals are shown for wild-type and mutant larval nuclei. Note the smooth appearance of the nuclei in the absence of D1, the smaller space occupied by chromatin and the overall absence of differentially condensed regions of chromatin relative to wild-type nuclei. Bar = 5 μm.