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dictyNews Volume 26 Number 15
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.
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Abstracts
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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]
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Announcement
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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-Franoise
Luciani and Pierre Golstein
Submitted by: Ludwig Eichinger [ludwig.eichinger@uni-koeln.de],
Francisco Rivero [francisco.rivero@uni-koeln.de]
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[End dictyNews, volume 26, number 15] 
