Transport and Turnover of Microtubules in Frog Neurons Depend on the Pattern of Axonal Growth. S. Chang, V. I. Rodionov, G.G. Borisy and S. V. Popov J. Neurosci., 18(3):821-829, 1998

The transport of axonal microtubules in growing neurites has been a controversial issue because of clear but conflicting results obtained with fluorescence marking techniques. We have attempted to resolve the discordance through analysis of the relationship between apparent microtubule translocation and cell adhesion. Neuronal cultures were prepared from Xenopus embryos 1 day following injection of Cy3-conjugated tubulin into one of the blastomeres of 2-cell stage embryos. Anterograde translocation of axonal microtubules was observed in neurons cultured on a laminin-coated surface, in agreement with previously published data for Xenopus embryonic neurons. However, when neuronal cultures were prepared on a concanavalin A-treated surface, the axonal microtubules were stationary, as reported for all other neurons investigated to date. Neuronal cultures prepared on laminin- and concanavalin A-coated surfaces also demonstrated dramatic differences in the pattern of axonal growth, dynamics of axonal microtubules and response to brefeldin A treatment. Our findings suggest that transport and dynamics of axonal microtubules may be directly affected by the mechanical tension produced by growth cone activity.

	Figure 1 (96K) - Anterograde movement of photobleached MTs in elongating Xenopus neurite growing on laminin-coated substrate
	Figure 2 (96K) - MTs remain stationary during axonal growth on Con A-coated substrate
	Figure 3 (96K) - MTs remain stationary in rapidly growing neurites plated on Con A-coated surface in the presence of neurotrophic factors
	Figure 4 (96K) - Quantitative assessment of the movement of bleached zones
	Figure 5 (64K) - Quantitative analysis of the fluorescence recovery in the bleached zones
	Figure 6 (192K) - Axonal growth on Con A-coated substrate
	Figure 7 (160K) - Effect of Brefeldin A treatment on axonal growth
	Figure 8 (96K) - Quantitative analysis of the effects of BFA on axonal growth on laminin (A) and Con-A (B)-coated surfaces

	Sequence 1 (800 K) - Corresponds to Figure 1. Anterograde movement of photobleached MTs in elongating Xenopus neurite growing on laminin-coated substrate Covers 20 minutes of real time.
	Sequence 2 (544 K) - Corresponds to Figure 2. MTs remain stationary during axonal growth on Con A-coated substrate Covers 34 minutes of real time.
	Sequence 3 (640 K) - Corresponds to Figure 3. MTs remain stationary in rapidly growing neurites plated on Con A-coated surface in the presence of neurotrophic factors Covers 30 minutes of real time.