Fig. 2
Lack of Mxc leads to premature accumulation of nuclear Pros in NBs.  A–E’ Confocal images of the third-instar larval brains of wt (A–A’), mxc RNAi (THU0893, THU5844) (B–C’), mxc RNAi with UAS-Mxc (D–D’) and UAS-Mxc (E–E’), labeled by anti-Pros (red) and anti-Dpn (green). In wt larval central brains, no nuclear Pros was detected in the NBs. Pros (arrowheads) was detected in the nucleus of NBs in mxc RNAi lines. This phenotype was rescued by UAS-Mxc. No phenotypes were detected in UAS-Mxc lines. All of these lines were driven by wor-Gal4. CB represents the central brain region, and OL represents the optical lobe region. Scale bars: 20 μm. F Statistics on nuclear Pros in the NBs in larval central brains of wt, mxc RNAi and Mxc rescue. The data are plotted as mean ± SD. **p < 0.01 using a Student’s t test, p = 0.0010. Numbers of NBs counted N = 360, N = 740, N = 69, N = 108, N = 187, respectively. G Schematic of Mxc protein structures in wt, mxc16a − 1, and mxc22a − 6. The 1837–amino acid Mxc protein contains a LisH domain (amino acids 6–38) and a SIF domain (amino acids 39–185) at the N-terminal, as well as a AT-hook motif at residues 1523–1535. mxc16a − 1 contains a deletion of 4 bp (TTCG) at the F1823 residue of Mxc, resulting in a frameshift at the C-terminal. It encodes an 1868–amino acid protein. mxc22a − 6 encodes a nonsense mutation at the N480 residue of the Mxc protein, resulting in a truncated protein containing 510 amino acids [10, 32]. H Statistics on nuclear Pros in the neuroblasts in larval central brain of wt, mxc16a − 1 and Mxc rescue. The data are plotted as mean ± SD. ***p < 0.001 using a Student’s t test, p = 0.0007. Numbers of neuroblasts counted N = 360, N = 373, N = 153, respectively. I The protein levels of Mxc were decreased in mxc knockdown larval brains compared to wt. MPM-2 antibody was used to recognize Mxc signals in this experiment. (J–L’) Confocal images of the larval brains of wt (J–J’), mxc16a − 1 (K–K’), and mxc16a − 1 with UAS-Mxc (L–L’) at 120 h AEL, labeled by anti-Pros (red), anti-Dpn (green), and Dapi (blue). Pros (arrowheads) was detected in the nucleus of mxc16a − 1 larval NBs (K). This phenotype was well rescued by worniu driven UAS-Mxc (L). Scale bars: 20 μm. (M–N’) MARCM clones of wt (M–M’) and mxc22a − 6 (N–N’) in third-instar larval brains, labeled by anti-Pros (red), anti-Dpn (blue) and anti-GFP (green). Nuclear Pros (arrowhead) was not detected in wt NBs (M), but was detected in mxc22a − 6 NBs (N). Numbers of clones observed n = 3, n = 3, respectively. Scale bars: 10 μm