Fig. 4. Retrograde transport of TeNT H_C depends on intact MTs. A scheme of the experiment is shown at the top. (A) MNs were incubated with TeNT H_C-Alexa488 and treated with 5 µM Vin after the appearance of fluorescent carriers. The majority of carriers stops or oscillates (arrowhead, arrow). Intervals between frames are 20 seconds. The cell body is located at the bottom. See video 3. (B) Quantitative analysis of TeNT H_C transport after MT disruption. Results are expressed as a percentage of the total carriers observed (control = 364, Vin = 361; n=2). (C) EM analysis of neurite cross-sections shows that MTs are absent in Vin-treated cells, whereas their density is unchanged in Lat B-treated cells. Data are expressed as a percentage of MT density observed in untreated MNs (control = 58; Vin = 36; Lat B = 24 neurites). The same cells used in A were immunostained for ß-tubulin. Treatment with Vin causes the accumulation of tubulin in paracrystals (D). Vin treatment is specific and does not affect F-actin visualized with fluorescent phalloidin (E). Bars, 5 µm (A) and 10 µm (D,E).

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