dictyNews Electronic Edition Volume 31, number 11 October 3, 2008 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. Upon publication of your paper, please send strains and plamids to  the Dicty Stock Center. For more information see  http://dictybase.org/StockCenter/Deposit.html. Back issues of dictyNews, the Dicty Reference database and other useful information is available at dictyBase - http://dictybase.org. ========= Abstracts ========= Kin Discrimination Increases with Genetic Distance in a Social Amoeba Elizabeth A. Ostrowski1*, Mariko Katoh2*, Gad Shaulsky2, David C. Queller1, Joan E. Strassmann1 1. Department of Ecology and Evolutionary Biology, Rice University, Houston, TX 7005 2. Department of Molecular and Human Genetics, Baylor College of Medicine, Houston, TX  77030 *Contributed equally to this work. PLoS Biology, in press In the social amoeba Dictyostelium discoideum, thousands of cells  aggregate upon starvation to form a multicellular fruiting body, and  approximately 20% of them die to form a stalk that benefits the others.   The aggregative nature of multicellular development makes the cells  vulnerable to exploitation by cheaters, and the potential for cheating is  indeed high.  Cells might avoid being victimized if they can discriminate  among individuals and avoid those that are genetically different.  We tested  how widely social amoebae cooperate by mixing isolates from different  localities that cover most of their natural range.  We show that different  isolates partially exclude one another during aggregation, and there is a  positive relationship between the extent of this exclusion and the genetic  distance between strains.  Our findings demonstrate that D. discoideum  cells co-aggregate more with genetically similar than dissimilar individuals,  suggesting the existence of a mechanism that discerns the degree of  genetic similarity between individuals in this social microorganism. Submitted by: Elizabeth Ostrowski [ostrowski@rice.edu] -------------------------------------------------------------------------------- How human leukocytes track down and destroy pathogens: Lessons learned from the model organism Dictyostelium discoideum Tian Jin1*, Xuehua Xu2, Jun Fang3, Nilgun Isik1, Jianshe Yan1, Joseph A. Brzostowski4, and Dale Hereld5 Immunologic Research, in press Human leukocytes, including macrophages and neutrophils, are phagocytic immune cells that capture and engulf pathogens and subsequently destroy them in intracellular vesicles.  To accomplish this vital task, these leukocytes utilize two basic cell behaviors –– chemotaxis for chasing down infectious pathogens and phagocytosis for destroying them.  The molecular mechanisms controlling these behaviors are not well understood for immune cells.  Interestingly, a soil amoeba, Dictyostelium discoideum, use these same behaviors to pursue and injest its bacterial food source and to organize its multi-cellular development.  Consequently, studies of this model system have provided and will continue to provide us with mechanistic insights into the chemotaxis and phagocytosis of immune cells.  Here, we review recent research in these areas that have been conducted in the Chemotaxis Signal Section of NIAID's Laboratory of Immunogenetics. Submitted by: Tian Jin [tjin@niaid.nih.gov] ============================================================== [End dictyNews, volume 31, number 11]