Figure 4

The Madm loss- or reduction-of-function phenotypes strongly resemble bunA phenotypes. (a-c) Scanning electron micrographs of eyFLP/FRT mosaic eyes. (d) Madm mosaic heads (b, c) contain significantly fewer ommatidia than control mosaic heads (a) (n = 6). (a'-c') Images of tangential eye sections showing that Madm mutant (unpigmented) ommatidia (b', c') display an autonomous reduction in rhabdomere size relative to wild-type sized (pigmented) ommatidia. Furthermore, differentiation defects such as misrotation and missing photoreceptors are observed in Madm mutant ommatidia. Clones were induced 24-48 h after egg deposition using the hsFLP/FRT technique. (e) Rhabdomere size of Madm-mutant ommatidia is significantly reduced (by 29-56%). The area enclosed by rhabdomeres of photoreceptors R1-R6 in unpigmented mutant ommatidia was compared to the area measured in pigmented wild-type sized ommatidia. For each genotype, three pairs of ommatidia without differentiation defects from three different eye sections were measured (n = 9). Significant changes are marked by asterisks, **p < 0.01 and ***p < 0.001 (Student's t-test) in (d) and (e). (f) Heteroallelic combinations of the hypomorphic Madm allele 3T4 produce few viable small flies (<10% of the expected Mendelian ratio) that can be rescued by one copy of a genomic Madm rescue construct. (g) The dry weight of Madm hypomorphic females is reduced by 37% compared to control flies (Df/+). One copy of a genomic rescue construct restores normal weight. The genomic rescue construct has no significant dominant effect on dry weight ('rescue Df/+' females do not significantly differ from 'Df/+' females). n = 15, except for Df/3T4 (n = 9). (h) Tangential section of an eye from a Madm hypomorphic mutant female displaying rotation defects (yellow asterisk), missing rhabdomeres (green asterisk), and cell-fate transformations (red asterisk). (i) Wings of hypomorphic Madm males exhibiting wing notches and an incomplete wing vein V (arrows). Genotypes are: (a, a') y, w, eyFlp or hsFlp/y, w; FRT82B/FRT82B, w⁺, cl^3R3 or M. (b, b', c, c') y, w, eyFlp or hsFlp/y, w; FRT82B, Madm^{7L2 or 3G5}/FRT82B, w⁺, cl^3R3 or M; (Df/+) y, w; FRT82B/Df(3R)Exel7283; (Df/3T4) y, w; FRT82B, Madm^3T4/Df(3R)Exel7283; (rescue Df/3T4) y, w; gen.Madm(LCQ139)/+; FRT82B, Madm^3T4/Df(3R)Exel7283; (rescue Df/+) y, w; gen.Madm(LCQ139)/+; FRT82B/Df(3R)Exel7283.