Figure 4

Viable bunA mutant flies are small, have elevated lipid levels, and display eye differentiation defects. The EP-element GE12327 inserted in the 5' UTR of bunA (intron of bunF; Figure 1E) is a hypomorphic bunA allele and gives rise to adult flies either homozygous or in combination with bunA alleles. (A) Homozygous bunA mutant females (top right) are smaller than heterozygous females (top left). A precise excision line of GE12327, termed ΔGE12327, serves as control. (B-D) Statistical analyses of weight, ommatidial size and number, and lipid levels of hypomorphic bunA mutants. All results are shown relative to values of GE12327/ΔGE12327 control flies (= 100%). Significant changes (p ≤ 0.05) are marked by asterisks. The allele A-211B behaved akin to A-149B in all assays. (B) Flies with reduced bunA function are lighter than control flies. Allele A-149B affects body weight in a dominant manner. 100% corresponds to 0.370 mg in females and 0.197 mg in males, respectively; n ≥ 35. (C) Eyes of hypomorphic bunA mutant females contain fewer and smaller ommatidia, indicating that both cell number and cell size are reduced. Again, allele A-149B dominantly lowers ommatidia number and size. 100% corresponds to 727 ommatidia; n = 8. (D) Females with severely lowered bunA function (A-149B/GE12327) have elevated lipid contents. 100% = 0.697 cal/mg fresh weight; n = 10. (E and F) Tangential eye sections of A-Q578X/GE12327 females reveal differentiation defects, schematically illustrated in (E' and F'). (E') The zigzag line demarcates the equator. Underrotated ommatidia are shown in red, and blue circles indicate fused ommatidia. (F') Yellow circles represent R7 to R1/6 transformations, and green circles indicate R4 to R3 transformations.