Fig. 7. GOBP2 expression in larval antennae and maxillary palps. (A–C) Mouth parts. Frontal (A), side (B) and ventral (C) views of the oral region, illustrating the position of larval antennae (Ant) and maxilla with associated palps and galea. OC, ocelli. (A,B) Fifth and (C) fourth instar larvae. (D–I) Antenna. Single larval antennae shown diagrammatically (D), in whole mount (E) and in section (F–I). (E) A whole-mount in situ hybridization using the antisense GOBP2Msex RNA probe (G2is). (F–I) Immunoreactions using GOBP2Msex antiserum (G2ab). (D) is modified from Kent and Hildebrand (1987), with segments I, II and III indicated. Small arrows, three basiconic sensilla on the end of the second segment; large arrowhead, three basiconic sensilla on the tip of the third segment; asterisks, mechanosensory spines. (J–N) Maxilla. Larval maxilla shown diagrammatically (J), in whole mount (K,L) and in section (M,N). (K,L) Whole-mount in situ hybridizations using the antisense GOBP2Msex RNA probe (G2is). (M,N) Immunoreactions using GOBP2Msex antiserum (G2ab). (J) is modified from Hanson and Dethier (1973), showing palp and galea. S, styloconic sensilla; B, basiconic-like sensilla on the tip of the maxillary palp. Arrowhead points to region on third segment of maxillary palp containing several pore-plate sensilla. Asterisks note positions of extirpation in the experiments of Hanson and Dethier (1973), which suggested differential roles of these structures in feeding decisions. (O,P) Controls. Control antennae (O) and maxilla (P) probed with PBP1Msex antiserum (Pab). All tissues (E-I, K-P) are from day-3 fifth instar larvae (actively feeding), except for L, which is from a fourth instar larva. Arrows over histology indicate positive staining. Arrowheads indicate third antennal segment (E,I) and point of cuticular contact of stain in third palp segment (L,M). Size bar (lower right), 542 µm (A,B), 104 µm (E), 58 µm (F), 65 µm (G), 72 µm (H), 48 µm (I), 148 µm (K), 100 µm (L), 116 µm (M,N), 66 µm (O), 116 µm (P).
