Cell motility assays

This report summarises practical aspects to measuring cell motility in culture. The methods described here were discussed at a 1-day European Tissue Culture Society (ETCS-UK) workshop organised by John Masters and Gareth E Jones that was held at University College London on 19th April 2007.     

Cell motility: deaf Drosophila keep the beat

Intraflagellar transport is involved in the assembly of cilia and eukaryotic flagella. Two recent studies have shown that defects in intraflagellar transport prevent assembly of sensory cilia in Drosophila, leaving the fly deaf and uncoordinated. Surprisingly, the mutant sperm flagella have normal structure and motility.     

Cell motility: the integrating role of the plasma membrane

The plasma membrane is of central importance in the motility process. It defines the boundary separating the intracellular and extracellular environments, and mediates the interactions between a motile cell and its environment. Furthermore, the membrane serves as a dynamic platform for localization of various components which actively participate in all aspects of the motility process, including force generation, adhesion, signaling, and regulation. Membrane transport between internal membranes and the plasma membrane, and in particular polarized membrane transport, facilitates continuous reorganization of the plasma membrane and is thought to be involved in maintaining polarity and recycling of essential components in some motile cell types. Beyond its biochemical composition, the mechanical characteristics of the plasma membrane and, in particular, membrane tension are of central importance in cell motility; membrane tension affects the rates of all the processes which involve membrane deformation including edge extension, endocytosis, and exocytosis. Most importantly, the mechanical characteristics of the membrane and its biochemical composition are tightly intertwined; membrane tension and local curvature are largely determined by the biochemical composition of the membrane and the biochemical reactions taking place; at the same time, curvature and tension affect the localization of components and reaction rates. This review focuses on this dynamic interplay and the feedbacks between the biochemical and biophysical characteristics of the membrane and their effects on cell movement. New insight on these will be crucial for understanding the motility process.     

Plasmodium vivax under the microscope: the Aotus model

The Aotus model for vivax malaria is extremely useful both as a source of living parasites in non-endemic areas, and as a model for vaccine and drug development research. Several species of New World primates can be infected with numerous different strains of Plasmodium vivax. This article reviews some aspects of the Aotus model, discusses the frequently observed hematological changes that can confound interpretation of hemogram data during the course of vivax infection, and provides a partial atlas of parasite forms and Aotus nancymai blood cells.     

Cell spreading and motility: A model lamellipod

Cells moving in vitro do so by means of a motile appendage, the lamellipod. This is a broad, flat sheet of cytogel which spreads in front of the cell and pulls the cell forward. We present here a mathematical model for lamellipodial motion based on the physical chemistry of actomyosin gels.     

Cell motility and the formation of lamellipodia

A report on work presented at the 39th Annual Meeting of the American Society for Cell Bilogy, Washington DC, December 11-15, 1999     

Cell motility of sporozoan protozoa

Parasitic protozoa need to be capable of movement. This is particularly important for their ability to locate and invade target cells or the organs of their hosts, and could therefore represent a novel target for chemotherapy or immune-mediated attack. Unlike the crawling movement of amoebae and vertebrate fibroblasts, sporozoon protozoa are characterized by a 'gliding movement' in which no obvious changes occur in cell shape. Here Conrad King discusses cellular motility particularly in sporozoites of Eimeria and Plasmodium, discussing current ideas about the possible motor mechanisms involved.     

Cell motility: ARNOand ARF6 at the cutting edge.

The transition of epithelial cells from a stationary to a motile state is important in embryogenesis, wound repair and metastasis. Recent studies have shown that ARNO and ARF6 play significant roles in coordinating this transition, providing new insight into the interplay between the Rho and ARF families of GTPases.     

Amyloid under the atomic force microscope

The atomic force microscope (AFM) is a versatile instrument that can be used to image biological samples at nanometre resolution as well as to measure inter and intra-molecular forces in air and liquid environments. This review summarises the use of AFM applied to protein and peptide self-assembly systems involved in amyloid formation. The technical principles of the AFM are outlined and its advantages and disadvantages are highlighted and discussed in the context of the rapidly developing field of amyloid research.     

Cell motility through plasma membrane blebbing

Plasma membrane blebs are dynamic cytoskeleton-regulated cell protrusions that have been implicated in apoptosis, cytokinesis, and cell movement. Influencing Rho-guanosine triphosphatase activities and subsequent actomyosin dynamics appears to constitute a core component for bleb formation. In this paper, we discuss recent evidence in support of a central role of nonapoptotic membrane blebbing for cell migration and cancer cell invasion as well as advances in our understanding of the underlying molecular mechanisms. Based on these studies, we propose that in a physiological context, bleb-associated cell motility reflects a cell's response to reduced substratum adhesion. The importance of blebbing as a functional protrusion is underscored by the existence of multiple molecular mechanisms that govern actin-mediated bleb retraction.