dictyNews Electronic Edition Volume 28, number 2 January 19, 2007 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 ========= Exploiting new terrain: an advantage to sociality in the slime mold Dictyostelium discoideum Jennie J. Kuzdzal-Fick , Kevin R. Foster , David C. Queller , and Joan E. Strassmann Behavioral Ecology, in press Advance Access published on January 8, 2007, DOI 10.1093/beheco/arl102. Understanding the ecological benefits of social actions is central to explaining the evolution of social behavior. The social amoeba Dictyostelium discoideum has been well studied and is a model for social evolution and development, but surprisingly little is known about its ecology. When starving, thousands of the normally solitary amoebae aggregate to form a differentiated multicellular organism known as a slug. The slug migrates toward the soil surface where it metamorphoses into a fruiting body of hardy spores held up by a dead stalk comprising about one-fifth of the cells. Multicellularity in D. discoideum is thought to have evolved to lift the spores above the hazards of the soil where spores can be picked up for long-distance dispersal. Here, we show that multicellularity has another advantage: local dispersal to new food sources. We find that cells shed by D. discoideum slugs during migration consume and remove bacteria in the path of the slug, although slugs themselves do not breakup. We also show that slugs are adept at local dispersal by comparing migration of slugs with migration of individual cells of the mutant, CAP2, which cannot aggregate and so rely only on cellular movement. In particular, the solitary cells of the aggregation mutant are unable to cross a soil barrier, easily crossed by slugs. We propose that the exploitation of local food patches is an important selective benefit favoring multicellular cooperation in D. discoideum. Submitted by Jennie Kuzdzal-Fick [jkuzdzal@rice.edu] -------------------------------------------------------------------------------- Vectors For Expression Of Proteins With Single Or Combinatorial Fluorescent Protein And Tandem Affinity Purification Tags In Dictyostelium Marcel Meima¤, Karin E. Weening and Pauline Schaap* School of Life Sciences, University of Dundee, Dundee, DD15EH, UK Protein Expression and Purification, in press. We constructed a series of expression vectors for purification of native proteins and protein complexes in Dictyostelium. Protein purification is achieved by either a C-terminal or N-terminal fusion of the protein of choice to the tandem affinity purification (TAP) tag. The TAP tag consists of a protein A tag and a calmodulin binding peptide (CBP) and has been successfully used for purification of native protein complexes from yeast and animal cells. Protein expression is driven by the constitutive actin 15 promoter and the vectors optionally carry additional green- or yellow fluorescent protein (GFP or YFP) tags for fusion at either a C- or N-terminal location. Tandem affinity purification of native Dictyostelium protein complexes was tested by using pArc-34, one of the members of the well characterized Dictyostelium Arp2/3 complex, as bait. After denaturation and SDS-PAGE separation of the pArc-34 associated proteins all members of the Arp2/3 complex could be identified. Submitted by Pauline Schaap [p.schaap@dundee.ac.uk] -------------------------------------------------------------------------------- Identification and domain mapping of Dictyostelium discoideum type-1 protein phosphatase inhibitor-2 Juliana M. Sousa-Canavez, Daniela Beton, Daniela C. Gonzalez-Kristeller and Aline M. da Silva Biochimie, in press Protein phosphatase type-1 catalytic subunit (PP1c) does not exist freely in the cell and its activity must be very strictly controlled. Several protein inhibitors of PP1c have been described including the classical mammalian inhibitor-1 (I-1) and inhibitor-2 (I-2). Association of these inhibitors with PP1c appears to involve multiple contacts and in the case of I-2 no less than five I-2 interaction subdomains have been proposed. In this report, we provide both in vitro and in vivo evidence that the Dictyostelium discoideum genome encodes a protein (DdI-2) that is an ortholog of mammalian I-2 being the first PP1c interacting protein characterized in this social amoeba. Despite the low overall sequence similarity of DdI-2 with other I-2 sequences and its long N-terminal extension, the five PP1c interaction motifs proposed for mammalian I-2 are reasonably conserved in the Dictyostelium ortholog. We demonstrate that DdI-2 interacts with and inhibits D.discoideum PP1c (DdPP1c), which we have previously characterized. Moreover, using yeast two-hybrid assays we show that a stable interaction of DdI-2 with DdPP1c requires multiple contacts. Submitted by: Juliana de Sousa-Canavez [jums@iq.usp.br] ============================================================ [End dictyNews, volume 28, number 2]