Somatic dppd12 mutant clones at the anterior/posterior (A/P) compartmental boundary do not interfere with cell growth and proliferation of adjacent cell populations in third instar larval wing disc. Inducing the mutant clones in a Minute background gives them a growth advantage and in some such discs the A/P stripe of dpp expression is almost completely lacking, yet the cell proliferation in the wing pouch is unperturbed. Severely reduced wing discs are observed only when the mutant clones are induced very early in development.
The wings of dppd8/dppd12 mutants do not develop at all, only rudimentary stubs are formed, this can be rescued by expression of Ecol\lexALG.dpp>dpplexAop.cHa.EGFP : the wings of these adults display venation defects (extra vein material at the anterior crossvein, loss of distal part of L4) and the have slightly elongated shape but their sizes are comparable to that of control wings. The wing size of these rescued flies can in turn be reduced again by hindering the spreading of the dpp morphogen: completely blocking it by co-expressing Zzzz\vhhGFP4Ecol\lexAop.morphotrap.ext.T:Disc\RFP-mCherry at the source, i.e. within the dpp expression domain or reducing it by expressing Zzzz\vhhGFP4Scer\UAS.morphotrap.ext.T:Disc\RFP-mCherry under the control of Scer\GAL4hh.PU (i.e. in the posterior compartment). The former blocks the wing blade development completely, with the latter the blade size is strongly decreased and the patterning in its posterior part is lost.
Blocking dpp spreading at its source however does not interfere with the uniform proliferation pattern in larval imaginal discs as the density of mitotic cells (pH3-positive) is comparable between the rescue and morphotrap discs. Clonal growth rates are also not generally affected (assessed by utilizing the Raeppli tissue-labelling tool), but in the morphotrap wing discs low numbers of very small clones (1-3) are found next to the A/P boundary and these are not observed in the control discs.
In wing discs where dpp spreading is blocked within the dpp expression domain, the growth of the lateral part of the wing compartments shows similar width increase and similar growth rate as in the control discs with dpp spreading unhindered. However, the proliferation of the medial cell population (marked by low brk) is abolished, so the overall size of wing disc is visibly decreased compared to controls.
Similarly, hindering the dpp spreading at its (anterior) source reduces the size of the posterior wing pouch by more than 60%, blocking the dpp spreading in the posterior compartment (by expressing the morphotrap under the control of Scer\GAL4hh.PU) decreased the posterior pouch size by about 40%.
The wings of dppd5/dppd12 mutants are so small that the identification of patterning defects is obscured.
dppd12/dppd6 flies show a considerable loss of taste bristles but do not show a loss of pseudotrachae or a significant change in gross mediproboscis morphology.
The size of the capitellum of the haltere is reduced in dppd5/dppd12 adults compared to wild type.
dppd5/dppd12 females have normal vaginal plates and tergite eight, showing discretely reduced analia in a few cases. dppd5/dppd12 males have extensively reduced terminalia and the penis apparatus can be duplicated or triplicated.
The genital disc is severely reduced in dppd12/dppd14 larvae.
The wing blade is almost entirely missing in dppd8/dppd12 animals. Some wing hinge structures are present.
dppd6/dppd12 flies have a reduced number of ommatidia. The adults are weak, short-lived (live for 2-3 days) and have abnormalities in the wing, leg, antenna and external genitalia. The tarsal and meta-tarsal segments of all legs are abnormal in dppd6/dppd12 flies, due to loss of claws and fusion of the tarsal segments. The dorsal parts of the leg are sometimes ventralised. The tibia and femur are progressively less affected, while the trochanter and coxa are almost wild type. The number of sex comb bristles is generally higher than normal. dppd6/dppd12 flies have defects in the distal segments of the antenna. The arista is usually absent and a conical projection is present on the third segment (which presumably represents the fused 4th, 5th and 6th antennal segments). The leg and antennal discs of dppd6/dppd12 larvae are deformed. Most dppd6/dppd12 males completely lack external genitalia while some have abnormal external genitalia. There is little effect on the female genitalia.
The external genitalia of dppd6/dppd12 and dppd8/dppd12 males are reduced to a small ring like structure. The external genitalia of dpp10638/dppd12 males are highly defective and the penis apparatus is less defective. dppd6/dppd12 and dpp10638/dppd12 females show duplication of the thorn bristles accompanied by an absence of long bristles. dppd8/dppd12 females show a complete duplication of the thorn bristles of the vaginal plate.
Heterozygotes are phenotypically wild-type.
Homozygous clones induced in first instar larvae produce abnormalities in the dorsal side of the leg. Pattern elements from the dorsal side are missing, and may or may not be replaced with a duplicate version of the remaining ventral part of the leg. Duplications are arranged as mirror images. Homozygous clones doubly mutant for dppd12 and wgl-17 show defects in both the ventral and dorsal sides of the leg. The frequency of duplications is reduced compared to the single mutant homozygous dppd12 or wgl-17 clones.
dppd8/dppd12 dics wing pouch is small, almost no wing tissue remains, except structures for the proximal hinge region. The proximal costa remains in the anterior compartment and a reduced alula in the posterior. Partial rescue of the wing phenotype is achieved by tkvQ253D.Scer\UAS.cLa expression driven by Scer\GAL4dpp.blk1.
Mutation partially suppresses the penetrance of the hhMrt phenotype.
Heterozygotes with dppd5 have reduced wings. dppd5/dppd12 heterozygotes have reduced wings. Some dppd12 ptcG20/dppd5 ptc16 individuals eclose and show a partial rescue of the ptc phenotype (decrease in the numbers of bristles on the notum, legs and antennae and number of teeth in the male sex comb and a reduction in size of overgrown structures).
Heterozygotes of dppd12 and dppd14 have the distal leg structures missing.
A posterior clone runs along the antero-posterior boundary until it reaches a gap in wing vein 4 (a region sensitive to lack of dpp) where the border of the clone becomes irregular.
medulla neuropil ommatidia In dppd12/dppd6 or dppd12/dppd14 flies the medulla neuropil is reduced to a size similar to that produced by inactivating wg prior to 44hr AEL. The number of ommatidia is correspondingly reduced.
Rudimentary imaginal discs.
In dppd12/dppd14 heterozygotes all imaginal discs are extremely reduced, die as early pupae. Imaginal disc transplantation demonstrates that only the anterior notum and most of the proximal anterior wing margin are produced. Wing discs do not have regenerative capacities.