dictyNews Electronic Edition Volume 41, number 11 May 29, 2015 Please submit abstracts of your papers as soon as they have been accepted for publication 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. Follow dictyBase on twitter: http://twitter.com/dictybase ========= Abstracts ========= A deep coverage Dictyostelium discoideum genomic DNA library replicates stably in E. coli Rafael D. Rosengarten, Pamela R. Beltran and Gad Shaulsky Department of Molecular and Human Genetics Baylor College of Medicine, Houston, TX Genomics, accepted for publication The natural history of the amoeba Dictyostelium discoideum has inspired scientific inquiry for seventy-five years. A genetically tractable haploid eukaryote, D. discoideum appeals as a laboratory model as well. However, certain rote molecular genetic tasks, such as PCR and cloning, are difficult due to the AT-richness and low complexity of its genome. Here we report on the construction of a ~20 fold coverage D. discoideum genomic library in E. coli, cloning 4 Ð 10 kilobase partial restriction fragments into a linear vector. End-sequencing indicates that most clones map to the six chromosomes in an unbiased distribution. Over 70% of these clones contain at least one complete open reading frame. We demonstrate that individual clones and library composition are stable over multiple replication cycles. Our library will enable numerous molecular biological applications and the completion of additional speciesÕ genome sequences, and suggests a path towards the long-elusive goal of genetic complementation. Submitted by Gad Shaulsky [gadi@bcm.edu] ---------------------------------------------------------------------- Secreted cyclic-di-GMP induces stalk cell differentiation in the eukaryote Dictyostelium discoideum Minireview Zhi-hui Chen and Pauline Schaap# College of Life Sciences, University of Dundee, Dundee DD15EH, UK J. Bacteriol., in press Cyclic-di-GMP is currently recognized as the most widely used intracellular signal molecule in prokaryotes, but roles in eukaryotes were only recently discovered. In the social amoeba Dictyostelium discoideum, c-di-GMP, produced by a prokaryote-type diguanylate cyclase, induces the differentiation of stalk cells, thereby enabling the formation of spore- bearing fruiting bodies. In this review, we summarize the currently known mechanisms that control the major life cycle transitions of Dictyostelium and focus particularly on the role of c-di-GMP in stalk formation. Stalk cell differentiation has characteristics of autophagic cell death, a process that also occurs in higher eukaryotes. We discuss the respective roles of c-di-GMP and of another signal molecule, DIF, in autophagic cell death in vitro and in stalk formation in vivo. Submitted by Pauline Schaap [p.schaap@dundee.ac.uk] ---------------------------------------------------------------------- Temporal regulation of kin recognition maintains recognition-cue diversity and suppresses cheating Hsing-I Ho and Gad Shaulsky Department of Molecular and Human Genetics, Baylor College of Medicine, Houston, TX Nature Communications, in press Kin recognition, the ability to distinguish kin from non-kin, can facilitate cooperation between relatives. Evolutionary theory predicts that polymorphism in recognition cues, which is essential for effective recognition, would be unstable. Individuals carrying rare recognition cues would benefit less from social interactions than individuals with common cues, leading to loss of the genetic cue-diversity. We test this evolutionary hypothesis in Dictyostelium discoideum, which forms multicellular fruiting bodies by aggregation and utilizes two polymorphic membrane proteins to facilitate preferential cooperation. Surprisingly, we find that rare recognition variants are tolerated and maintain their frequencies among incompatible majority during development. Although the rare variants are initially excluded from the aggregates, they subsequently rejoin the aggregate and produce spores. Social cheating is also refrained in late development, thus limiting the cost of chimerism. Our results suggest a potential mechanism to sustain the evolutionary stability of kin recognition genes and to suppress cheating. Submitted by Gad Shaulsky [gadi@bcm.edu] ============================================================== [End dictyNews, volume 41, number 11]