ISSN:
0886-1544
Keywords:
actin
;
cytoskeleton
;
dynamic instability
;
protozoa
;
video microscopy
;
Life and Medical Sciences
;
Cell & Developmental Biology
Source:
Wiley InterScience Backfile Collection 1832-2000
Topics:
Biology
,
Medicine
Notes:
Microtubule dynamics has been studied extensively in vitro, but comparatively little information is available on the in vivo behavior of microtubules. Here we report on the assembly, disassembly, and sliding of microtubules in the giant freshwater amoeba, Reticulomyxa. We have found that treating the cell with 0.25% trypsin induces the rapid formation of exceedingly flat areas within the reticulopodial network, allowing for the direct observation of microtubule behavior by DIC optics and computer-enhanced video microscopy. In flattened areas, microtubule sliding occurs at rates of between 1 and 6.5 μm/sec. The average rate of microtubule assembly is 1.6 μm/sec, while microtubule disassembly takes place at about 4 μm/sec and can reach up to 19.5 μm/sec. We also observed many cases where a microtubule forms a hairpin loop and eventually breaks, resulting in bidirectional disassembly from the point of breakage. Our observations demonstrate sliding of cytoplasmic microtubules in vivo. The high rates of microtubule assembly/disassembly in this cell type are difficult to reconcile with conventional views of association and dissociation processes at microtubule ends and suggest unconventional mechanisms for the growth and shrinkage of microtubules.
Additional Material:
11 Ill.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1002/cm.970170308
