Fig. 4
From: A fat-tissue sensor couples growth to oxygen availability by remotely controlling insulin secretion
Airway branching is reduced in breathless-knockdown animals. a Tracheae ramifying to the fat body were measured in larval segments A2/A3, illustrated in overview here. b, c Knockdown of breathless (btl) in tracheae leads to a reduction in branching of the terminal tracheal cells of the fat body branch compared with the btl > + control (btl > crossed to w1118). Representative images (b) and quantification (c) of the fat-body branch of larval tracheal terminal cells are shown. Scale bar, 50 µm. PB, primary branch; SB, secondary branch; TB, tertiary branch. c: n = 4. d Whole-body transcript levels of branchless (bnl), encoding the hypoxia-inducible FGF ligand of Btl, is strongly upregulated in larvae with trachea-specific btl knockdown, suggesting that tissues are experiencing hypoxia in these animals. n = 4–5. e Loss of btl renders animals unable to survive in a low-oxygen environment (5% O2 levels), whereas most btl > + controls are able to develop to pupariation. n = 3. Statistics: Student’s t-test for pairwise comparisons. *P < 0.05, ***P < 0.001, compared with the control. Error bars indicate SEM. Underlying data are provided in the Source Data file
