Fig. 1: 5-HT1B expressed in cardiac cells controls lymph gland dispersal and wasp egg encapsulation following wasp parasitism.

A5-HT1B-Gal4(KI)>LacZ^nls (green), and Col (red) expression in wild type (wt) second instar larvae (L2). 5-HT1B (green) is expressed in a subset of anterior aorta cells (white arrowhead). B–B”’5-HT1B-Gal4(KI)>LacZ^nls (green), and Antp (red) expression in wild type (wt) third instar larvae (L3). 5-HT1B (green) is expressed in all anterior aorta cells (white arrowhead) except those that express Antp (red arrowhead). B’–B”’ Magnification of the white square drawn in (B) shows complementary stainings of LacZ (green, white arrowhead) and Antp (red, red arrowhead) in anterior aorta nuclei. A, B at least three independent experiments were analyzed. C Schematic representation of a third instar lymph gland anterior lobe, and anterior aorta (orange). Nuclei of cardiac cells expressing 5-HT1B are drawn in green while those expressing Antp are in red. MZ and CZ represent medullary and cortical zones, respectively. D, E Quantification (%) of wasp egg encapsulation when HandΔ> (D) or 76E11 (E) are used as cardiac cell drivers to express 5-HT1B-RNAi, or in a 5-HT1B amorphic mutant (5-HT1B^ΔIII-V). The mean of three independent experiments is represented: control n = 119 (D) and 179 (E); 5-HT1B-RNAi n = 76 (D) and 120 (E); 5-HT1B^ΔIII-V n = 120 (D). F Quantification of lymph gland disruption (%) 10H post parasitism. Lymph glands were classified into three groups (see “Materials and methods”). Quantification represents the mean of three independent biological replicates: control n = 85, 5-HT1B-RNAi n = 76. Error bars represent SEM. Statistical test: Pearson’s Chi-squared test, one-tailed. *** p < 0.001. For (D–F), source data are provided as a Source Data file. Nuclei are labelled with DAPI (blue). Scale bars, 20 μm.