Fig. 6. ey^D is a mutation in the ey gene. (A) The ey^D mutation is a translocation from the second chromosome into the fifth exon of the ey gene. At the top, the exons of the ey mRNAs (coding region in black, untranslated leader and trailer in white) are mapped with respect to the EcoRI sites of genomic ey DNA, which have been derived from genomic and cDNA sequences provided by FlyBase (Hauck et al., 1999) and from 5'-RACE products obtained from poly(A)⁺ RNA of 0- to 20-hour-old embryos raised at 25°C. Below, the corresponding EcoRI map of the ey^D chromosome is illustrated. The ey^D mutation is shown to consist of an insertion after the 305th bp of exon 5, replacing the adjacent 320 bp. The insertion, which is a large reversed repeat of the 23D1,2 to 24BC region from the second chromosome, has been characterized by mapping and sequencing genomic clones isolated from an ey^D library in DASH II. The EcoRI map of two of these clones, EYD.1 and EYD.36, covering the proximal and distal breakpoint of the insertion, respectively, are shown at the bottom. Note that the ends of the large reversed repeat (hatched) are not identical but that the distal end extends 779 bp further into 24BC (stippled), while the proximal end includes a roo transposon, inserted at the indicated location. A 327 bp insertion (bearing no similarity to sequences of known genomes) in the ey^D chromosome, close to the distal end of the large insertion (190 bp downstream of the 5' end of ‘intron 5’), is indicated by a small triangle. R, EcoRI. (B) The ey^D insertion generates a truncated Ey protein. The wild-type Ey protein of 898 amino acids, including a paired-domain P and prd-type homeodomain H (Quiring et al., 1994), is compared to the truncated Ey^D protein resulting from the 2nd chromosome insertion into exon 5 of the ey gene. The truncated protein consists of 346 amino acids and includes the N-terminal paired-domain and a Ser/Thr-rich domain (28/66 amino acids), possibly an activation domain, but no homeodomain. Its 32 C-terminal amino acids are encoded by the inserted sequences of the second chromosome (black). The positions of introns are indicated by arrowheads. (C-E) Characterization of the ey^D mutation, a translocation of the second chromosome into the ey gene. In situ hybridization to polytene chromosomes of ey^D/ci^D spa^pol late third instar larvae with the DIG-labeled probes indicated in A that are specific for the ends of the 2nd chromosome insertion (C), the 5' end (D), and the 3' end (E) of the ey gene. The inserts in C show enlarged views of the regions of hybridization on the second chromosome (lower left) and at the ends of the insertion on the fourth chromosome (upper right).

Return to article