ago1/agoΔ3-7 third instar larvae have tracheal defects, with the most prevalent phenotype being an approximate doubling of the number of cytoplasmic branches elaborated from multiple subtypes of terminal cells, including the lateral LH and LG terminal cells. Other defects include terminal branch tangles and the development of 'ringlet'-shaped ganglionic branches, which are seen in approximately 25% of larvae.
ago1/ago3 transheterozygous mutants develop through all embryonic stages but fail to hatch as L1 larvae.
ago1/Df(3L)Exel9000 transheterozygous mutants develop through all embryonic stages but fail to hatch as L1 larvae.
ago1/ago3 mutant embryos exhibit defects in the developing trachea. The earliest of these are interruptions or 'breaks' in the continuity of the tracheal lumen. Approximately 70% of these mutants display breaks throughout the tracheal system and are prominent in the dorsal trunk, the lateral trunk, and between dorsal branches of opposing tracheal placodes. The dorsal branches and ganglionic branches also appear to show misrouting. The second prominent tracheal phenotype (occurring in 25% of embryos) is excess lumen convolution through the primary and secondary branches. Mutants have approximately the same number of nuclei per dorsal trunk segment, indicating that the primary effect of ago loss in the dorsal trunk is not on cell number, but on fusion cell migration and fusion.
In ago1 homozygous embryos, 2% of hemisegments have two RP2 sibs and one RP2 neuron, while others have two RP2 neurons and one sib, rather than the one cell of each type seen in each segment in wild-type embryos.
Homozygous mutant clones in the wing disc and in the adult eye are consistently larger and contain more cells than their respective twin spots. Despite the faster rate of cell division in mutant cells, cells of homozygous wing disc clones are not decreased in size compared to control cells.
When ago1 mutant clones are induced in the ovary, some mutant cysts have only a single, large, highly polyploid germ-line cell.
Adult eyes mosaic for mutations in ago are composed mostly of mutant tissue, exhibiting a proliferative advantage over their wild-type twin-spots.