Related Experiment Video
Updated: Jul 11, 2026
10:03
Quantitative Locomotion Study of Freely Swimming Micro-organisms Using Laser Diffraction
Published on: October 25, 2012
Spiroplasma swim by a processive change in body helicity
Joshua W Shaevitz1, Joanna Y Lee, Daniel A Fletcher
1Department of Integrative Biology, University of California, Berkeley, 459 Evans Hall, Berkeley, California 94720, USA. jshaevitz@berkeley.edu
Cell
|September 24, 2005
Summary
Tiny helical bacteria, Spiroplasma, swim using a novel mechanism. Instead of flagellar rotation, they generate propulsion through kink pairs propagating along their bodies, enabling directional movement.
Area of Science:
- Microbiology
- Biophysics
- Bacterial motility
Background:
- Microscopic organisms require unique strategies for locomotion in liquid environments.
- Prokaryotic swimming is typically achieved through flagellar rotation.
- Spiroplasma are helical bacteria known to infect plants and insects.
Purpose of the Study:
- To investigate the swimming mechanism of Spiroplasma.
- To elucidate the biophysical principles underlying Spiroplasma motility.
- To identify alternative bacterial locomotion strategies beyond flagellar rotation.
Main Methods:
- Quantitative analysis of cell kinematics during free swimming.
- High-resolution microscopy to observe bacterial movement.
- Biophysical modeling of wave propagation and cell deformation.
Main Results:
- Spiroplasma propulsion is generated by the propagation of kink pairs along the cell body.
- A dynamic change in cell helicity creates propulsive waves.
- This mechanism enables directed movement in liquid.
Conclusions:
- Spiroplasma employ a unique, non-flagellar swimming mechanism.
- Kink-pair propagation and dynamic helicity changes are key to their motility.
- This discovery expands our understanding of bacterial locomotion strategies.
Related Concept Videos
01:23Membrane Fluidity
Cell membranes are composed of phospholipids, proteins, and carbohydrates loosely attached to one another through chemical interactions. Molecules are generally able to move about in the plane of the membrane, giving the membrane its flexible nature called fluidity. Two other features of the membrane contribute to membrane fluidity: the chemical structure of the phospholipids and the presence of cholesterol in the membrane.Fatty acids tails of phospholipids can be either saturated or...
01:26Membrane Fluidity
Membrane fluidity is explained by the fluid mosaic model of the cell membrane, which describes the plasma membrane structure as a mosaic of components—including phospholipids, cholesterol, proteins, and carbohydrates—that gives the membrane a fluid character.
Mosaic nature of the membrane
The mosaic characteristic of the membrane helps the plasma membrane remain fluid. The integral proteins and lipids exist as separate but loosely-attached molecules in the membrane. The membrane is a relatively...
Mosaic nature of the membrane
The mosaic characteristic of the membrane helps the plasma membrane remain fluid. The integral proteins and lipids exist as separate but loosely-attached molecules in the membrane. The membrane is a relatively...
01:15Mechanisms of Membrane-bending
The living membranes are flexible due to their fluid mosaic nature; however, their bending into different shapes is an active process regulated by specific lipids and proteins. The membrane bending can be transient as seen in vesicles or stable for a long time as in microvilli. Cells regulate the size, location, and duration of the membrane curvature.
Membrane bending can happen due to intrinsic changes in lipid composition or extrinsic association with different proteins. The proteins involved...
Membrane bending can happen due to intrinsic changes in lipid composition or extrinsic association with different proteins. The proteins involved...
01:25Aquaporins
Aquaporins or AQPs are a family of integral membrane proteins whose primary function is to transport water, while some called aquaglyceroporins also transport glycerol. In addition, aquaporins have also been suspected to be involved in transporting volatile substances, such as carbon dioxide and ammonia, across membranes. Such AQPs that act as gas channels are often highly expressed in cells involved in the gaseous exchange, such as red blood cells, epithelial cells, and pulmonary capillaries.
01:16Cell Motility through Blebbing
Blebs are a type of membrane protrusion formed by the internal hydrostatic pressure of the cytoplasm. Blebs are observed in several cell types, including fibroblasts, immune cells, and single-celled organisms like the amoeba. The primary function of blebs is cell locomotion and apoptosis, but they are also found during necrosis and cell division. The life cycle of a bleb comprises an initiation phase followed by the expansion and retraction phases.
Blebbing Through the Matrix
In multicellular...
Blebbing Through the Matrix
In multicellular...
01:27Diversity of Protists IV
Amoebozoa represent a diverse group of terrestrial and aquatic protists that utilize lobe-shaped pseudopodia for locomotion and feeding. This characteristic differentiates them from the Rhizaria, which possess threadlike pseudopodia. The primary classifications within Amoebozoa include gymnamoebas, entamoebas, and the plasmodial and cellular slime molds. Phylogenetic evidence indicates that Amoebozoa diverged from a lineage that ultimately gave rise to fungi and animals.Gymnamoebas and...