Figure 4.14 The Role of Microfilaments in Cell Movement—Showing Cause and Effect in Biology
To confirm that cell movement in Amoeba proteus is mediated by microfilaments, Amoeba were treated with the drug cytochalasin B, a drug that inhibits microfilament formation. Results showed that treated Amoeba round up and do not move, whereas untreated Amoeba continue to move, consistent with a role for microfilaments in Amoeba movement. This experiment is a clear example of the use of inhibition to demonstrate cause and effect. While the results from this experiment implicate microfilaments in amoeboid cell movement, they do not address the question of whether other cytoskeletal components, such as microtubules, are also essential for movement. To answer this question, one could treat Amoeba with colchicine, a drug that breaks apart microtubules. If microtubules are not involved in amoeboid cell movement, then treated Amoeba would be expected to remain unaffected by colchicine treatment.
Original Papers
Wessells, N. K., B. S. Spooner, J. F. Ash, M. O. Bradley, M. A. Luduena, E. L. Taylor, J. T. Wrenn, and K. M. Yamada. 1971. Microfilaments in Cellular and Developmental Processes. Science 171: 135–143.
http://www.jstor.org/stable/1731391
Pollard, T. D. and R. R. Weihing. 1974. Actin and myosin and cell movement. Critical Reviews in Biochemistry and Molecular Biology 2: 1–65.
http://dx.doi.org/10.3109/10409237409105443
Links
Spooner, B. S., K. M. Yamada, and N. K. Wessells. 1971. Microfilaments and cell locomotion. Journal of Cell Biology 49: 595–613.
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC2108496/
Bradley, M. O. 1973. Microfilaments and cytoplasmic streaming: inhibition of streaming with cytochalasin. Journal of Cell Science 12: 327–343.
http://jcs.biologists.org/cgi/reprint/12/1/327.pdf
Molecular Expressions Digital Video Library: Pond Life—Amoeba (Protozoa) Movies
http://micro.magnet.fsu.edu/moviegallery/pondscum/protozoa/amoeba/index.html
The Journal of Cell Science: The Extended Tubulin Superfamily
http://jcs.biologists.org/cgi/reprint/114/15/2723
Wikipedia: Cytochalasin
http://en.wikipedia.org/wiki/Cytochalasin
Wikipedia: Colchicine
http://en.wikipedia.org/wiki/Colchicine
Fuchs, E., and D. W. Cleveland. 1998. A Structural Scaffolding of Intermediate Filaments in Health and Disease. Science 279: 514–519.
http://www.jstor.org/stable/2894032