dictyNews Electronic Edition Volume 26, number 15 May 19, 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 ============= A protein in crude cytosol regulates glucose-6-phosphatase activity in crude microsomes to regulate group size in Dictyostelium Wonhee Jang and Richard H. Gomer Howard Hughes Medical Institute and Department of Biochemistry and Cell Biology, Rice University, Houston, TX J. Biol. Chem, in press Dictyostelium discoideum form groups of ~2 x 104 cells. The group size is regulated in part by a negative feedback pathway mediated by a secreted multi-polypeptide complex called counting factor (CF). The CF signal transduction pathway involves CF repressing internal glucose levels by increasing the Km of glucose-6-phosphatase. Little is known about how this enzyme is regulated. Glucose-6-phosphatase is associated with microsomes in both Dictyostelium and mammals. We find that the activity of glucose-6-phosphatase in crude microsomes from cells with high, normal, or low CF activity had a negative correlation with the amount of CF present in these cell lines. In crude cytosols (supernatants from ultracentrifugation of cell lysates), the glucose-6-phosphatase activity had a positive correlation with CF accumulation. The crude cytosols were further fractionated into a fraction containing molecules greater than 10 KDa (S>10K) and molecules less than 10 KDa (S<10K). S>10K from wild-type cells strongly repressed the activity of glucose-6-phosphatase in wild-type microsomes, while S>10K from countin- cells (cells with low CF activity) significantly increased the activity of glucose-6-phosphatase in wild-type microsomes by decreasing Km. The regulatory activities in the wild-type and countin- S>10KÕs are heat labile and protease sensitive, suggesting that they are proteins. S<10K from both wild-type and countin- cells did not significantly change glucose-6-phosphatase activity. Together, the data suggest that, as a part of a pathway modulating multicellular group size, CF regulates one or more proteins greater than 10 KDa in crude cytosol that affect microsome-associated glucose-6-phosphatase activity. Submitted by: Richard Gomer [richard@rice.edu] ----------------------------------------------------------------------------- ============== Announcement ============== A new book on Dictyostelium methods will be available end of June from Humana Press Inc (http://humanapress.com). Methods in Molecular Biology: Dictyostelium discoideum Editors: L. Eichinger and F. Rivero The Humana Press Inc, Totowa, USA Table of contents Preface Part I: The Organism, Community Resources and Genome-wide Studies 1. The Secret Lives of Dictyostelium (review chapter) Richard H. Kessin 2. The Genome of Dictyostelium discoideum (review chapter) Adam Kuspa and William F. Loomis 3. The cDNA Sequencing Project (review chapter) Hideko Urushihara, Takahiro Morio and Yoshimasa Tanaka 4. dictyBase and the Dicty Stock Center (review chapter) Petra Fey, Pascale Gaudet, Karen E. Pilcher, Jakob Franke and Rex L. Chisholm 5. Analysis of gene expression using cDNA microarrays Marcel Kaul and Ludwig Eichinger 6. Proteomic Analysis of Dictyostelium discoideum Udo Roth, Stefan Mueller, Franz-Georg Hanisch Part II: Basic Methods and Molecular Genetic Techniques 7. Cultivation, Spore production, and Mating Hideko Urushihara 8. Parasexual Genetics Using Axenic Cells Jason King and Robert Insall 9. Slug phototaxis, thermotaxis and spontaneous turning behaviour Paul R. Fisher and Sarah J. Annesley 10. Purification techniques of subcellular compartments for analytical and preparative purposes Laurence Aubry and Gerard Klein 11. Generation of multiple knock-out mutants using the Cre-loxP system Alan R. Kimmel and Jan Faix 12. Restriction Enzyme-Mediated Integration (REMI) Mutagenesis Adam Kuspa 13. RNA interference and antisense mediated gene silencing in Dictyostelium. Markus Kuhlmann, Blagovesta Popova and Wolfgang Nellen Part III: Imaging and Localisation Methods 14. Application of Fluorescent Protein Tags as Reporters in Live Cell Imaging Studies Annette Mueller-Taubenberger 15. Investigating gene expression: in situ hybridization and reporter genes Ricardo Escalante and Leandro Sastre 16. Application of 2D and 3D DIAS to Motion Analysis of Live Cells in Transmission and Confocal Microcopy Imaging Deborah Wessels, Spencer Kuhl and David R. Soll 17. Using Quantitative Fluorescence Microscopy and FRET Imaging to Measure Spatiotemporal Signaling Events in Single Living Cells Xuehua Xu, Joseph A. Brzostowski and Tian Jin 18. Visualising signalling and cell movement during the multicellular stages of Dictyostelium development Dirk Dormann and Cornelis J. Weijer 19. Under Agarose Chemotaxis of Dictyostelium discoideum David Woznica and David A. Knecht 20. Optimised fixation and immunofluorescence staining methods for Dictyostelium cells. Monica Hagedorn, Eva M. Neuhaus and Thierry Soldati 21. Cryofixation methods for ultrastructural studies of Dictyostelium discoideum Mark J. Grimson and Richard L. Blanton Part IV: Dictyostelium as Model Organism 22. Analysis of Signal Transduction - Formation of cAMP, cGMP and Ins(1,4,5)P3 in vivo and in vitro Peter J. M. Van Haastert 23. Assaying Chemotaxis of Dictyostelium cells Michelle C. Mendoza and Richard A. Firtel 24. Characterization of Cross-linked Actin Filament Gels and Bundles Using Birefringence and Polarized Light Scattering Ruth Furukawa and Marcus Fechheimer 25. Quantitative and microscopic methods for studying the endocytic pathway Francisco Rivero and Markus Maniak 26. Preparation of intact, highly purified phagosomes from Dictyostelium Daniel Gotthardt, Regis Dieckmann, Vincent Blancheteau, Claudia Kistler, Frank Reichardt and Thierry Soldati 27. Assaying cell-cell adhesion Salvatore Bozzaro 28. Periodic activation of ERK2 and partial involvement of G-protein in ERK2 activation by cAMP in Dictyostelium cells Mineko Maeda 29. An improved method for Dictyostelium centrosome isolation Irene Schulz, Yvonne Reinders, Albert Sickmann and Ralph Graef 30. Epigenetics in Dictyostelium Markus Kaller, Wolfgang Nellen and Jonathan R. Chubb 31. Dictyostelium discoideum as model to study host-pathogen interactions Can Uenal and Michael Steinert 32. Pharmacogenetics: Defining the genetic basis of drug action and inositol trisphosphate analysis Kathryn E. Adley, Melanie Keim and Robin S.B.Williams 33. How to assess and study cell death in Dictyostelium discoideum Artemis Kosta, Catherine Laporte, David Lam, Emilie Tresse, Marie-Fran¨oise Luciani and Pierre Golstein Submitted by: Ludwig Eichinger [ludwig.eichinger@uni-koeln.de], Francisco Rivero [francisco.rivero@uni-koeln.de] ============================================================================== [End dictyNews, volume 26, number 15]