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. ============= Abstracts ============= 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]. ----------------------------------------------------------------------------- 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 2Dˇpartment de Biochimie, Facultˇ des Sciences, Universitˇ 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 ŌblebsÕ 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] ============================================================================== [End dictyNews, volume 26, number 19]