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. 2018 Aug 23;14(8):e1007618. doi: 10.1371/journal.pgen.1007618

Fig 2. ITP regulates desiccation survival independently of its action on the water storage under ad libitum feeding.

Fig 2

(A) Impl2-GAL4 is a suitable driver to target several of the ITP-expressing neurons. Impl2-GAL4-driven expression of GFP partially overlaps with the ITP immunoreactivity (ITPir); scale bars 50 μm. Upper panel: brain neurons. Note the ipc-1 and ipc-2a neurosecretory cells are covered by the Impl2 expression pattern, whereas the rest of the ipc-2 (marked in middle figure) and ipc-3 interneurons (asterisks) are not. Median panel: neurons in the terminal abdominal ganglia that express ITP do not express of Impl2>GFP. iag = ITPir abdominal ganglia neurons. Lower panel: peripheral lateral bipolar dendrite (LBD) neurons in the seventh and eighth abdominal segment express both Impl2>GFP and ITP (ant anterior, lat lateral). (B) Summary table listing partially overlapping expression pattern of Impl2-GAL4 and ITP. (C) ITPi driven by both Impl2-based TARGET and da-GeneSwitch effectively decreases ITP mRNA. Two-tailed Student’s t–test: P < 0.01 for the TARGET manipulations and P < 0.001 for the GeneSwitch manipulation. F1 generation of the cross between the ITPi line and w1118 was used as a control (off conditions) for the TARGET-based experiment. (D) ITPi driven by the Impl2- based TARGET does not affect the proportion of body fluids. Two-tailed Student’s t–test: P > 0.05 for both comparisons with controls. (E) ITPi driven by the Impl2-based TARGET reduces survival under desiccation. Log-rank test: P < 0.001 for comparisons with both controls. Sample size: tub-GAL80ts; Impl2-GAL4 n = 87; ITPi n = 83; tub-GAL80ts; Impl2>ITPi n = 49. (F) Mild ITPi driven by the daGS induced by 50 μM RU-486 does not affect body fluids. Two-tailed Student’s t–test: P > 0.05 for comparisons with the non-induced conditions. Strong ITPi driven by the daGS induced by 200 μM RU-486 reduces body water. Two-tailed Student’s t–test: P < 0.05. (G) Mild ITPi driven by the daGS induced by 50 μM RU-486 reduces survival under desiccation. Log-rank test: P < 0.05. The detrimental effect of ITPi on desiccation resistance is dose-dependent; induction by 50 μM RU-486 has a milder effect than induction by the 200 μM RU-486. Log-rank test: P < 0.01. Sample size: 0 μM RU-486 n = 61; 50 μM RU-486 n = 45; 200 μM RU-486 n = 40.