The Drosophila melanogaster Phospholipid Flippase dATP8B Is Required for Odorant Receptor Function
(A) Electroantennogram (EAG) and (B) electropalpogram (EPG) responses to a panel of odorants. Bars represent mean response ± SEM (n = 10), asterisks are significant differences. Responses of homozygous ll2 mutant flies (blue bars) are severely reduced when compared with controls (black bars) for all the tested odorants except CO2 (t-test, Bonferroni, p<0.05). Heterozygote flies (grey bars) are not affected. (C) A deletion that removes dATP8B and a piggyBac element inserted in dATP8B both fail to complement the ll2 phenotype. Bars represent mean EAG responses ± SEM (n = 6–10). Trans-heterozygotes for ll2 and deficiency Df(3R)Exel8155 (blue bars) have reduced EAG response compared to controls (black bars, t-tests, Bonferroni, p<0.05), and homozygotes for the piggyBac insertion dATP8Bf05203 (red bars) and trans-heterozygotes for ll2 and dATP8Bf05203 (red/blue hatch) show similar reductions when compared to heterozygote controls (grey bars; t-tests, Bonferroni, p<0.05). (D) The mapped genomic interval for the ll2 mutant and the gene model of dATP8B (CG14741). The candidate region contained 14 annotated genes. The identified nonsense mutation in dATP8B and the insertion site of the piggyBac line dATP8Bf05203 are in the 1st and the 10th common coding exon respectively, affecting all the annotated transcripts. For isoforms RC, RF, RG, RH and RI the EMS mutation causes R18-X and for isoforms RB and RD the mutation causes R197-X. Coding exons are colored in orange and the 3′ and the 5′ UTR are in grey. (E) The olfactory defect in the dATP8Bf05203 line is reverted when the piggyBac insertion is precisely excised. EAG responses of homozygous dATP8Bf05203-Ex flies (red bars) to a panel of odorants were not different from controls (black bars). Bars represent mean response ± SEM (n = 5, t-test, Bonferroni). Odorants are: EA, ethyl acetate, PA, pentyl acetate, MS, methyl salicylate, OL, 1-octen-3-ol, HB, ethyl 3-hydroxybutanoate, EH, ethyl hexanoate, MH, 6-methyl-5-hepten-2-one, BZ, benzaldehyde, MP, 4-methylphenol, PO, paraffin oil (solvent blank).