Imaging axonal transport of mitochondria in vivo

Thomas Misgeld, Martin Kerschensteiner, Florence M Bareyre, Robert W Burgess & Jeff W Lichtman

Supplementary Figures and Text (pdf 2M)
Supplementary Figures 1–4, Supplementary Methods.

Supplementary Video 1 (mov 2M)
Time-lapse imaging of mitochondrial transport. The movie shows two axons in an intercostal nerve in the triangularis sterni explant. A node of Ranvier (NR) is present in the upper axon. The majority of mitochondria are immobile, but a fraction moves quickly (1-1.5 m / sec) in anterograde (left to right) and retrograde directions. At nodes of Ranvier transported mitochondria often slow down and sometimes stall, especially those transported in the retrograde direction (anterograde velocity crossing a node 0.73 0.06 m per sec, n = 25; retrograde 0.57 0.04 m per sec, n = 25). Time is indicated in min: sec.

Supplementary Video 2 (mov 2M)
Different mitochondrial populations in living axons in an acute nerve-muscle explant. The movie shows the intercostal axon represented in Figure 1d; boxes indicate the mitochondria highlighted there. The lower panel shows the same axon after image processing and intensity inversion. Time is indicated in min: sec.

Supplementary Video 3 (mov 2M)
Mitochondrial transport at an axonal branch point. Trifurcation in an intercostal axon in the triangularis sterni explant imaged for 45 minutes (thy1-mitoCFP-S x thy1-YFP-16). Numerous mitochondria enter the three different branches (# 1 - 3). A time-averaged version of this movie is shown in Supplementary Figure 3b. Note deceleration of many mitochondria as they transit the branch point. Time is indicated in min: sec.

Supplementary Video 4 (mov 2M)
Mitochondrial dynamics in growing and retreating sprouts. Two axon sprouts in an acute nerve-muscle explants prepared one week after axon transection in the living animal(thy1-mitoCFP-S x thy1-YFP-16; their location is indicated in Figure 2a). Over about 2 hours, the upper sprout retreats, while the lower one extends a growth cone. Mitochondria can be seen advancing into axonal varicosities along the stem of the growing sprout. Time is indicated in min: sec. CFP shown in cyan; YFP in yellow.

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