Figure 7.
Both mTOR and Erk signaling contribute to the excessive sheath length that results from ptena loss of function. A–I, Representative maximum projections of z-stack optical sections, focused from a lateral position at the trunk spinal cord, of 4 dpf Tg(sox10:GAL4-VP16, cmlc2:Cerulean);Tg(4xnrUAS:EGFP-CaaX, cmlc2:EGFP) larvae. A, Example of a single oligodendrocyte with numerous myelin sheaths (arrows) in a control-treated larva (n = 38 cells). B, Noticeably shorter sheaths are evident in a rapamycin-treated larva (n = 45 cells). C, Example of a single oligodendrocyte with numerous myelin sheaths in a U-0126-treated larva (n = 43 cells). D, Example of a single oligodendrocyte in a control-treated p53 MO injected larva (n = 30 cells). E, Noticeably shorter sheaths are evident in a rapamycin-treated larva injected with p53 MO (n = 27 cells). F, Example of a single oligodendrocyte in a U-0126-treated larva injected with p53 MO (n = 23 cells). G, Markedly longer sheaths are evident in a p53 and ptena MO-injected larva (n = 44 cells). H, I, Rapamycin-treated larva injected with both p53 and ptena MO (n = 47 cells), and U-0126-treated larva injected with both p53 and ptena MO (n = 38 cells) display noticeably shorter myelin sheaths. J–L, Graphs showing the average sheath length, average total sheath length, and sheath number per oligodendrocyte (n = at least 17 larvae for each treatment; p values were calculated using a Mann–Whitney test). Error bars represent the SEM. Scale bars, 10 μm.