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| Flux of Actin Subunits at the Leading Edge of Living Fibroblasts |
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| Y.-l. Wang (1985) |
| J. Cell Biol. 101:597-602. |
| Lamellipodia, where cultured cells undergo active forward protrusion, are packed with actin filaments. To investigate the dynamics of these actin filaments, cultured IMR33 gerbil fibroma cells were microinjected with fluorescently labeled actin. A laser microbeam was then used to bleach the fluorescence and create a small dark spot. Flux of actin subunits was detected as directional movement of the spot relative to the edge of the cell. |
| Rearward Movement of Bleached Spot in Stationary Cells |
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Size = 320 x 240 pixels.| This cell had an active lamellipodium but remained stationary during the period of observation. The bleached spot was created at the very edge of the cell. It subsequently moved toward the cell center, suggesting that actin monomers were adding continuously at the leading edge and pushing the filaments backwards. The other end of the filaments was most likely undergoing disassembly or fragmentation to maintain a constant overall width of lamellipodia. Large numbers indicate the number of seconds after photobleaching. |
| Stationary Bleached Spot in Forward Moving Cells |
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| In this cell, the leading edge moved forward while the bleached spot (small arrow slightly away from the edge) remained stationary relative to the substrate. |