Fig. 4.

Age-associated factors exacerbate GA spread. aThe expression of GA200 was induced for 3 days in Olfactory Receptor Neurons (ORNs) in young (2 days old) and old flies (30 days old), after which GA spread was measured. Fly cartoons were created with BioRender. b & c Representative images of control fly brains expressing mCherry in ORNs for 3 days in young (a) or old (b) flies. d & e Representative images of fly brains expressing GA200 in ORNs for 3 days in young (d) and old (e) animals. Brains were probed with an anti-GA antibody. The outline of ORN axons and synaptic terminals is shown in green. Insets of indicated areas highlight differences in the number of propagated dots across conditions. f Quantification of the total number of GA-positive dots detected outside of ORNs after 3 days of expression in young and old flies (age: ****P < 0.0001; genotype: ****P < 0.0001; interaction: ***P < 0.001; Two-way ANOVA, n = 5–9). g Quantification of the number of propagated GA-positive dots relative to the GA signal in ORNs after 3 days of expression in young and old flies (***P < 0.001, t-test). Scale bars in images and insets are 100 um and 10 um, respectively