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. 2016 Jun 16;12(6):e1006123. doi: 10.1371/journal.pgen.1006123

Fig 5. Neuronal SP signaling controls a mating-induced increase in GSC numbers dependent on ecdysteroid.

Fig 5

(A) Ecdysteroid levels in virgin (v) and mated (m) female ovaries isolated from adult female flies overexpressing the membrane bound form of SP (mSP) and transgenic SPR RNAi. Transgenes were driven by ppk-GAL4 or fru (NP21)-GAL4. (B) Mating-induced expression of ecdysteroid biosynthesis enzyme genes in the ovaries. The y-axis represents fold changes of transcript levels between the ovaries of mated and virgin females. Box plot shows 25–75% (box), median (band inside) and minima to maxima (whiskers). Most of the enzyme genes, except for nobo, transcriptionally increased by mating in control female ovaries (Gray: ppk/+). Increased transcript levels of nvd and phm by mating were suppressed in SPR RNAi females (Purple: ppk>SPR RNAi). (C and D) Frequencies of germaria containing one, two, and three GSCs (left y axis), and average number of GSCs per germarium (right y axis) in virgin (v) and mated (m) female flies of neuronal SPR RNAi adult female flies that were fed food supplemented with EtOH (for control) and 20E. (D) Females mated with SP null mutant males did not show mating-induced increase in GSCs and this phenotype was not rescued by oral administration of 20E. (E) Schematic of neuroendocrine control of a mating-induced increase in GSC numbers. Neuronal sex peptide signaling induced by mating increases GSC numbers via activated ovarian ecdysteroid biosynthesis. Since overexpression of SP, but not feeding of 20E into virgin females was sufficient to induce an increase in GSC numbers, there might be another pathway activated by SP to control GSC numbers (dotted arrow). Values are presented as the mean with standard error of the mean in A. The numbers of samples examined are indicated in parentheses in A, or inside bars in C, D. For statistical analysis, Dunnett’s test was used for A, Student’s t-test was used for B, a Mann-Whitney U test were used for C and D. ***P≤ 0.001, **P ≤ 0.01, *P ≤ 0.05, n.s., non-significant (P > 0.05).