dictyNews Volume 26 Number 19

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dictyNews 
Electronic Edition 
Volume 26, number 19 
June 30, 2006 

Please submit abstracts of your papers as soon as they have been 
accepted for publication by sending them to dicty@northwestern.edu 
or by using the form at 
http://dictybase.org/db/cgi-bin/dictyBase/abstract_submit. 

Back issues of dictyNews, the Dicty Reference database and other  
useful information is available at dictyBase - http://dictybase.org. 

 
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  Abstracts 
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Towards a molecular understanding of human diseases using Dictyostelium  
discoideum 

Robin S.B. Williams1, Katrina Boeckeler1, Ralph Graef2, Annette  
Mueller-Taubenberger3, Zhiru Li4, Ralph R. Isberg4,5, Deborah Wessels6,  
David R. Soll6, Hannah Alexander7, Stephen Alexander 7 

1. Department of Biology and the Wolfson Institute for Biomedical Research,  
University College London, London, WC1E 6BT, UK. 
2. Carl Zeiss AG, 85339 Hallbergmoos, Germany. 
3. Institut fuer Zellbiologie, Ludwig-Maximilians-Universitaet Muenchen,  
80336 Muenchen, Germany.  
4. Department of Molecular Biology and Microbiology, Tufts University  
School of Medicine, Boston, MA  02111, USA. 
5.  Howard Hughes Medical Institute, Tufts University School of Medicine,  
Boston, MA  02111, USA. 
6. W.M. Keck Dynamic Image Analysis Facility, Department of Biological  
Sciences, University of Iowa, Iowa Ci, IA, 52242, USA. 
7. Division of Biological Sciences, University of Missouri, Columbia,  
MO 65211, USA. 

 
Trends in Molecular Medicine, In press 

The social amoeba Dictyostelium discoideum is increasingly being used as a  
simple model for the investigation of problems important to human health.  
This article will focus on several recent examples of Dictyostelium-based  
biomedical research including the analysis of immune cell disease and  
chemotaxis, centrosomal abnormalities and lissencephaly, bacterial  
intracellular pathogenesis, the mechanisms of neuroprotective and  
anti-cancer drug action. The combination of cell, genetic and molecular  
biology techniques that are available in Dictyostelium often make the  
analysis of these problems more amenable to study in this system than in  
mammalian cell culture. Using Dictyostelium, findings have been made in  
these areas that in turn have driven research in mammalian systems and have  
established Dictyostelium as a powerful model for human disease analysis.  

 
Submitted by: RobinWilliams, R.S.B. [robin.williams@ucl.ac.uk] and Stephen  
Alexander [alexanderst@missouri.edu]. 
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Dissection of amoeboid movement into two mechanically distinct modes 

Kunito Yoshida1¤ and Thierry Soldati*1,2  

1Department of Biological Sciences, Sir Alexander Fleming Building, Imperial  
College, South Kensington, London SW7 2AZ, UK  
2DŽpartment de Biochimie, FacultŽ des Sciences, UniversitŽ de Genve,  
Sciences II, 30 quai Ernest Ansermet, CH-1211-Genve-4, Switzerland 

¤Current address: School of Biosciences, The University of Birmingham,  
Edgbaston, Birmingham,B15 2TT, U.K. 

 
Journal of Cell Science, in press 

The current dominant model of cell locomotion proposes that actin  
polymerization pushes against the membrane at the leading edge producing  
filopodia and lamellipodia that move the cell forward. Despite its success,  
this model does not fully explain the complex process of amoeboid motility,  
such as occurring during embryogenesis and metastasis. Here, we show that  
Dictyostelium cells moving in a physiological milieu continuously produce  
ÔblebsÕ at their leading edges, and demonstrate that focal blebbing  
contributes in large part to their locomotion. Blebs are well-characterized  
spherical hyaline protrusions that occur when a patch of cell membrane  
detaches from its supporting cortex. Their formation requires the activity  
of myosin II, and their physiological contribution to cell motility has not  
been fully appreciated. We find that pseudopodia extension, cell body  
retraction, and overall cell displacement are reduced under conditions  
that prevent blebbing, including high osmolarity, blebbistatin and in  
myosin II null cells. We conclude that amoeboid motility comprises two  
mechanically different processes characterized by the production of two  
distinct cell surface protrusions, blebs and filopodia/lamellipodia.  

 
Submitted by: Thierry Soldati [thierry.soldati@biochem.unige.ch] 
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[End dictyNews, volume 26, number 19]