Figure 5.
Figure 5. Speed, directionality, and branching defects after electroporation of the Tuba1a S140G-mutant construct. (A) Time-lapse video films were analyzed from control and S140G-mutant conditions, and mean instantaneous speeds were determined (short red line). Note the decrease in the mean speed of migration at 5 dpe with the mutant S140G construct. n = 140 cells per group from three independent experiments. (B) Quantification of directionality of migration: each cell was plotted according to the angle formed from the location at the beginning to the end of the migratory sequence (from 0 to 360° with 0°/360° being dorsal, 90° caudal, 180° ventral, and 270° rostral). Note the significant decrease in the percentage of neurons migrating tangentially and rostrally toward the OB after electroporation with the Tuba1a mutant S140G construct. n = 90 cells per group from three independent experiments. (C) The density of distribution for control Tuba1a instantaneous speed measurements was determined. The analysis revealed a bimodal distribution validated with Hartigan’s dip test (P < 0.01) and the AIC. n = 140 cells from control condition from three independent experiments. The threshold speed between fast- and slow-migrating neurons was defined mathematically at 75.48 µm/h. (D) Description of the four different categories of branching morphology used for the quantifications in E and F. Each category corresponds to a level of complexity of the migrating neurons with one, two, three, or four processes. (E) Among control Tuba1a neurons, no significant difference in category between fast and slow migration was observed (white and light gray bars). For Tuba1a S140G, less category 1 and more category 2 neurons were observed for both fast and slow migration (dark gray and black bars). Slow migrating mutant neurons (dark gray) showed even less category 1 and more category 2 neurons. n = 90 cells per group. Data are represented as mean ± SEM. (F) For control and mutant Tuba1a non-unidirectional neurons, a strong decrease of category 1 was observed concomitantly with an increase of category 2. For the mutant Tuba1a S140G neurons (salmon and orange bars specifically), the decrease of category 1 non-unidirectional neurons was associated with an increase of category 2, 3, and 4 neurons. Note that increased morphological complexity is associated with lack of directionality in both control and mutant conditions; however, mutant neurons show higher complexities. n = 100 cells per group. Data are represented as mean ± SEM. *, P < 0.05; **, P < 0.01; ***, P < 0.001.

Speed, directionality, and branching defects after electroporation of the Tuba1a S140G-mutant construct. (A) Time-lapse video films were analyzed from control and S140G-mutant conditions, and mean instantaneous speeds were determined (short red line). Note the decrease in the mean speed of migration at 5 dpe with the mutant S140G construct. n = 140 cells per group from three independent experiments. (B) Quantification of directionality of migration: each cell was plotted according to the angle formed from the location at the beginning to the end of the migratory sequence (from 0 to 360° with 0°/360° being dorsal, 90° caudal, 180° ventral, and 270° rostral). Note the significant decrease in the percentage of neurons migrating tangentially and rostrally toward the OB after electroporation with the Tuba1a mutant S140G construct. n = 90 cells per group from three independent experiments. (C) The density of distribution for control Tuba1a instantaneous speed measurements was determined. The analysis revealed a bimodal distribution validated with Hartigan’s dip test (P < 0.01) and the AIC. n = 140 cells from control condition from three independent experiments. The threshold speed between fast- and slow-migrating neurons was defined mathematically at 75.48 µm/h. (D) Description of the four different categories of branching morphology used for the quantifications in E and F. Each category corresponds to a level of complexity of the migrating neurons with one, two, three, or four processes. (E) Among control Tuba1a neurons, no significant difference in category between fast and slow migration was observed (white and light gray bars). For Tuba1a S140G, less category 1 and more category 2 neurons were observed for both fast and slow migration (dark gray and black bars). Slow migrating mutant neurons (dark gray) showed even less category 1 and more category 2 neurons. n = 90 cells per group. Data are represented as mean ± SEM. (F) For control and mutant Tuba1a non-unidirectional neurons, a strong decrease of category 1 was observed concomitantly with an increase of category 2. For the mutant Tuba1a S140G neurons (salmon and orange bars specifically), the decrease of category 1 non-unidirectional neurons was associated with an increase of category 2, 3, and 4 neurons. Note that increased morphological complexity is associated with lack of directionality in both control and mutant conditions; however, mutant neurons show higher complexities. n = 100 cells per group. Data are represented as mean ± SEM. *, P < 0.05; **, P < 0.01; ***, P < 0.001.

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