Nucleotide substitution: T978A. Amino acid replacement: Y?N. Missense mutation within the homeodomain.
T15994534A
Y258N | exd-PA; Y258N | exd-PB; Y258N | exd-PD; Y258N | exd-PE
Y?N
If the maternal component of exd is increased occasional pharate adults are obtained that can be dissected from the pupal case. These flies lack proximal leg structures while distal structures are normal. The survival of gynandromorph mosaic individuals is 41%. Abdominal segments 1 to 5 are unaffected and clones within segment 6 often retain their appropriate identity, those that are transformed have an A5 identity. Clones within abdominal segment 7 are always transformed anteriorly toward A6, evidenced by differentiation into a tergite lacking trichomes. Clones in female genitalia also show anterior-ward transformation, clones in the male genitalia have subtle effects. Clones in the head could encompass any region. Clones in the antenna cause a size reduction and slight thickening of the arista which may indicate a partial transformation toward leg. Mitotic clones in the distal tarsal regions of the leg survive and participate in normal patterning. Clones located in the proximal regions either do not survive, grossly distort pattern and reduce leg segment size or make ectopic clusters of bristles in regions of leg usually devoid of bristles. The segment identities of mutant legs are not affected.
Weak allele. Homozygotes die as pharate adults with specific cuticular defects. exdEM5 embryos lacking maternal as well as zygotic exd function have reduced denticle bands in T3 and T2 which resemble the wild-type T1 beard. The denticles and dorsal hairs of T1 are eliminated, the only remnants of T1 being the ventral pit and Keilin's organ.