Figure 4.

flower and azot Are Necessary for Amyloid-β42-Induced Neuronal Death

(A) Neurons compute relative levels of Flower^LoseB to determine its fate. Neurons expressing LoseB and surrounded by neurons with equal levels of LoseB do not activate azot transcription. If the neuron cannot cope with an insult and exhibits persistently higher levels of LoseB compared to neighboring neurons, it will fail to pass a fitness checkpoint mediated by the azot gene and will be purged from the tissue. Increased copies of azot enhance fitness-based cell elimination.

(B) Optic lobes of 2-week-old adults showing apoptotic neurons labeled by DCP1 (Drosophila caspase-protein 1) in red and ELAV in blue. Scale bar: 10 or 5 μm in the insets. At the bottom on the left panel is a dying neuron (arrow) from a single plane of the confocal projection displayed earlier, representative of the GMR > Aβ42 / > lacZ genotype. Scale bar: 2 μm.

(C) Quantification of positive DCP1, assuming the levels of apoptosis in GMR > Aβ42 / > lacZ are 100%.

(D) Tracing of suboptimal cells (green) through aging using the azot{KO;GFP} reporter in GMR > + flies or GMR > Aβ42 flies at 5, 15, or 30 days of life. DAPI marks cell nuclei (blue). Scale bar: 5 μm.

(E) Quantification of GFP-positive cells per optic lobe in GMR > + flies or GMR > Aβ42 flies at 5, 15, or 30 days of life.

Error bars show SEM. Ns: no significant. ^∗∗p < 0.01, ^∗∗∗p < 0.001. All genotypes are heterozygous. See also Figure S3.