Table II. Comparison of the motility of IC-1B and IC-2C dynein in cultured hippocampal neurons.
| 1B dynein | 2C dynein | |
|---|---|---|
| Number of videos | 42 | 33 |
| Puncta number (percentage of total) | ||
| Total | 857 | 757 |
| Stationarya | 431 (50%) | 481 (63%) |
| Jiggling movement | 274 (32%) | 178 (24%) |
| Excursive movement | 152 (18%) | 98 (13%) |
| Direction of excursive movement | ||
| Number (relative percentage) | ||
| Anterograde | 69 (45%) | 44 (45%) |
| Retrograde | 58 (38%) | 40 (41%) |
| Bidirectional | 25 (16%) | 14 (14%) |
| Observation time (s) | 840 | 660 |
| Frequency (motile puncta per second) | 0.507 | 0.418 |
Hippocampal neurons were transfected with either mRPF–IC-2C or mRFP–IC-1B, and dynein movement was imaged in axons 48 h later. Each dynein puncta was defined as being one of three classes: stationary, those puncta with no sign of movement; excursive, those puncta with movement greater than one pixel for four frames (1 pixel = 137 μm; 1 frame per 0.5 s); or jiggling, puncta whose side-to-side oscillatory motion did not meet the criteria for an excursion. Puncta that showed excursive movement were then defined as those moving exclusively anterograde, exclusively retrograde, or those that show bidirectional movement. The number of puncta in each category and the relative frequency are indicated.
More IC-2C dynein puncta are stationary than IC-1B dynein puncta; P < 0.0005, χ test).