Fig. 4

Larval LNs acquire different morphologies in adult ALs compared to larval patterns. a Scheme of two binary systems that together drive myr::smGdP reporter expression exclusively in larval LNs within adult brains. b 189Y-larval LNs show distinct morphologies in late 3rd instar larval brains. Four types of LNs were observed, as shown in b₁ (n = 22/68 SCCs), b₂, (n = 30/68 SCCs), b₃ (n = 9/68 SCCs), and b₄ (n = 7/68 SCCs). Supplementary Note 3 contains detailed descriptions of larval LNs in b and d. Yellow and white dashed lines contour ALs and SEZ, respectively. c The morphologies of 189Y-positive larval LNs in adult brains. c₁ Negative control flies were maintained at 18 °C throughout development, and no smGdP-labeled LNs were observed in adult brains (n = 43 brains). c₂ When flies were raised at 29 °C throughout development, both larval and adult-specific LNs were labeled (n = 26 brains). c₃–c₇ When flies were raised at 29 °C from embryonic stage and shifted to 18 °C at puparium formation, as many as four LNs were observed in the adult brains (arrowheads, n = 17 brains) (c₃). These LNs may have processes in dorso-medial glomeruli (c₄) or central glomeruli (c₅). Otherwise they may pack densely in a small subset of central glomeruli (c₆) or sparsely innervate multiple glomeruli (c₇). ALs are contoured by yellow dashed lines. d NP3056-larval LNs show distinct morphologies in late 3rd instar larval brains. The four types of LNs are shown in d₁ (n = 21/86 SCCs), d₂ (n = 24/86 SCCs), d₃ (n = 25/86 SCCs), and d₄ (n = 16/86 SCCs). Arrows indicate LN processes in dorsal brain regions. e Similar to c but for NP3056-GAL4. When flies were shifted to 18 °C at puparium formation, as many as four LNs were observed in adult brain (arrowheads, n = 54 brains) (e₁). These LNs may have processes that cover the central AL (e₂), innervate both ALs (e₃, arrow, bilateral LN), or the neuron may innervate VP1, VP2, and VP3 (e₃, arrowhead, oligo-glomerular LN). Asterisks denote neurons that are not LNs