Structure and mechanics of the spasmoneme, a biological spring within the protozoan Vorticella convallaria

Molecular springs have recently emerged as the basis for the fastest and most powerful movements at the cellular level in biology. The spasmoneme of the protozoan, Vorticella convallaria, is a model molecular spring, relying on energy stored in protein interactions to power contraction over a few hundred micrometers in a few milliseconds. While basic characteristics of Vorticella contraction are known, the underlying biochemical mechanism is unclear. The studies outlined here define and measure key parameters of spasmoneme performance which enable discrimination between proposed movement schemes and identification of new model parameters. Recent work has classified the spasmoneme as a power-limited machine (Upadhyaya, Baraban et al. 2007), where increases in viscous load correspond to decreases in velocity; in this work the maximum load at minimum velocity (the stall force), is measured. Work done by the stalk in contraction is shown to be dependent on its fractional change in length. This energy dependence arises from the basic underlying mechanism, and a major goal of this thesis was to characterize that mechanism by imaging the underlying structure. In the case of the Vorticella spasmoneme, imaging methods like birefringence imaging and electron microscopy, which do not require preexisting knowledge of protein identity, are particularly helpful.

Department dc:contributor.department

Massachusetts Institute of Technology. Biological Engineering Division.

Grantor dc:publisher

Massachusetts Institute of Technology

Year dc:date.issued

2007

Author dc:creator

• France, Danielle Cook

Advisor dc:contributor.advisor

• Paul T. Matsudaira.

• Biological Engineering Division.

Statement dc:rights

• MIT theses are protected by copyright. They may be viewed, downloaded, or printed from this source but further reproduction or distribution in any format is prohibited without written permission.

Licence dc:rights.uri

• http://dspace.mit.edu/handle/1721.1/39904
• http://dspace.mit.edu/handle/1721.1/7582

Language dc:language.iso

eng

Identifier URI

http://dspace.mit.edu/handle/1721.1/39904

OAI identifier oai:identifier

oai:dspace.mit.edu:1721.1/39904