CRY-positive processes in the medulla and lamina of Drosophila melanogaster.

Flies were examined at four ZTs: ZT1, ZT4, ZT13 and ZT16 (ZT0 – the beginning of the day and ZT12 – the beginning of the night) but images shown in Fig. 4 were obtained from the brain of individuals collected for experiments at different ZTs. ZT for each image is given in brackets. A1–3: cry-GAL4-driven GFP in the medulla and lamina. CRY-positive projection from lateral neurons (LN_vs) passes the medulla, invades the lamina (arrows), and terminates in the lamina corte (A1: ZT16, A2: ZT13, A3: ZT1). B1–3: Cells labeled with cry-GAL4-driven GFP (green) and REPO-immunolabeled glial cells (magenta). Numerous cells in the medulla and lamina are CRY-positive, but REPO-negative (arrow). CRY-positive projection from the LN_vs divides in the lamina cortex. The projection forms arborized processes with varicosities (asterisk) (ZT4). C1–2: Immunolabeling of the fenestrated glia with the antibody against DVMAT (magenta) and cry-GAL4-driven GFP in processes (green) in the lamina cortex. CRY-positive terminals do not invade the layer of the fenestrated glia (C2) (C1: ZT16, C2: ZT13). D1–3: Immunolabeling with BRP (magenta) antiserum and cells labeled with cry-GAL4-driven GFP (green). A neuron projecting from the LN_vs to the lamina does not form synaptic contacts with the lamina cells (D2) (D1,2: ZT1, D3: ZT4). RE – retina, LA – lamina, ME – medulla. Scale bars: 20 µm.