dictyNews Electronic Edition Volume 32, number 10 April 10, 2009 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 ========= Dictyostelium discoideum – a model for many reasons Sarah J. Annesley and Paul R. Fisher Department of Microbiology, La Trobe University VIC 3086, Australia Molecular and Cellular Biochemistry, in press. The social amoeba or cellular slime mould Dictyostelium discoideum is a “professional” phagocyte that has long been recognized for its value as a biomedical model organism, particularly in studying the actomyosin cytoskeleton and chemotactic motility in non-muscle cells. The complete genome sequence of D. discoideum  is known, it is genetically tractable, readily grown clonally as a eukaryotic microorganism and is highly accessible for biochemical, cell biological and physiological studies. These are properties it shares with other microbial model organisms. However Dictyostelium combines these with a unique life style, with motile unicellular and multicellular stages, and multiple cell types that offer for study an unparalleled variety of phenotypes and associated signalling pathways. These advantages have led to its recent emergence as valuable model organism for studying the molecular pathogenesis and treatment of human disease, including a variety of infectious diseases caused by bacterial and fungal pathogens. Perhaps surprisingly, this organism, without neurons or brain, has begun to yield novel insights into the cytopathology of mitochondrial diseases as well as other genetic and idiopathic disorders affecting the central nervous system. Dictyostelium has also contributed significantly to our understanding of NDP kinase, as it was the Dictyostelium enzyme whose structure was first determined and related to enzymatic activity. The phenotypic richness and tractability of Dictyostelium should provide a fertile arena for future exploration of NDPK’s cellular roles. Submitted by: Paul R Fisher [P.Fisher@latrobe.edu.au] -------------------------------------------------------------------------------- Switching direction in electric-signal-induced cell migration by cyclic guanosine monophosphate and phosphatidylinositol signaling. Sato MJ, Kuwayama H, van Egmond WN, Takayama AL, Takagi H, van Haastert PJ, Yanagida T, Ueda M. Proc Natl Acad Sci USA, in press Switching between attractive and repulsive migration in cell movement in response to extracellular guidance cues has been found in various cell types and is an important cellular function for translocation during cellular and developmental processes. Here we show that the preferential direction of migration during electrotaxis in Dictyostelium cells can be reversed by genetically modulating both guanylyl cyclases (GCases) and the cyclic guanosine monophosphate (cGMP)-binding protein C (GbpC) in combination with the inhibition of phosphatidylinositol-3-OH kinases (PI3Ks). The PI3K-dependent pathway is involved in cathode-directed migration under a direct-current electric field. The catalytic domains of soluble GCase (sGC) and GbpC also mediate cathode-directed signaling via cGMP, whereas the N-terminal domain of sGC mediates anode-directed signaling in conjunction with both the inhibition of PI3Ks and cGMP production. These observations provide an identification of the genes required for directional switching in electrotaxis and suggest that a parallel processing of electric signals, in which multiple-signaling pathways act to bias cell movement toward the cathode or anode, is used to determine the direction of migration. Submitted by: Masayuki Sato [satom@phys1.med.osaka-u.ac.jp] ============================================================== [End dictyNews, volume 32, number 10]