CSM News Electronic Edition Volume 5, number 9 September 23, 1995 Please submit abstracts of your papers as soon as they have been accepted for publication by sending them to CSM-News@worms.cmsbio.nwu.edu. Back issues of CSM-News, the CSM Reference database and other useful information is available by anonymous ftp from worms.cmsbio.nwu.edu [165.124.233.50], via Gopher at the same address, or by World Wide Web at the URL "http://worms.cmsbio.nwu.edu/dicty.html" ================================ Updated CSM Reference Database ================================ An updated version of the Franke database of the Cellular Slime Mold literature is now available by anonymous ftp from worms.cmsbio.nwu.edu in the directory pub/dicty/reference_database or via the web page . =========== Abstracts =========== Dictyostelium mucoroides cells exhibit cell-cycle dependent sorting behavior as observed in D. discoideum development Aiko Amagai* and Yasuo Maeda Biological Institute, Graduate School of Science, Tohoku University, Aoba, Sendai 980-77, Japan Develop. Growth Differ., in press. SUMMARY Evidence has been obtained indicating that the cell's position in the cell cycle at the onset of starvation is a naturally-occurring variable closely involved in the subsequent sorting and pattern formation during the development of Dictyostelium discoideum Ax2. It is of interest to know if a similar phenomenon is also noticed in species other than D. discoideum, and also without any treatment of cells for cell synchronization. For this, the sorting behavior of D. mocoroides-7 (Dm7 ) cells and its relation to the cell-cycle phase at the onset of starvation were analyzed, using nonsynchronized Dm7 cells pulse-labeled with 5'-bromo-2-deoxyuridine (BrdU). The results have demonstrated that Dm 7 cells starved at the early G2 phase aggregate most rapidly, but were eventually sorted out to the posterior prespore zone of migrating slugs. In contrast, the cells starved at the mid-late G2 phase exhibited slower aggregation, but were sorted out to the anterior zone (tip), thus being basically similar to the sorting behavior of D. discoideum cells. Measurements of cell number and nuclearity also provided evidence that about 80% of cells progressed their cell-cycle after formation of multicellular structures (mounds), probably coupling with prespore differentiation as the case for D. discoideum. Thus the cell-cycle dependent sorting during Dictyostelium development is most likely to be a common phenomenon recognized beyond difference of species. ---------------------------------------------------------------------- Molecular Cloning of an Intracellular P-type ATPase From Dictyostelium That is Upregulated in Calcium-adapted Cells John Moniakis, M. Barrie Coukell, and Arthur Forer Department of Biology, York University, 4700 Keele St., North York, Ontario, CANADA, M3J 1P3 J. Biol. Chem., in press SUMMARY Results from a number of laboratories suggest that intracellular Ca2+ is involved in the regulation of Dictyostelium discoideum growth and development. To learn more about the regulation and function of intracellular Ca2+ in this organism, we have cloned and sequenced cDNAs which encode a putative P-type Ca2+ ATPase designated patA. The deduced protein product of this gene (PAT1) has a calculated molecular mass of 120,718 daltons. It exhibits about 46% amino acid identity with Ca2+ ATPases of the PMCA family and lower identity with SERCA family members and monovalent cation pumps. However, PAT1 lacks the highly conserved calmodulin- binding domain present in the C-terminal region of most PMCA- type enzymes. When Dictyostelium amoebae are adapted to grow in the presence of 80 mM CaCl2, both the patA message and protein product are upregulated substantially. These cells also exhibit an increase in the rate and magnitude of intracellular P-type Ca2+-uptake activity. Immunofluorescence analysis indicates that PAT1 colocalizes with bound calmodulin to intracellular membranes, probably components of the contractile vacuole complex. The presence of PAT1 on the contractile vacuole suggests that in Dictyostelium this organelle might function in Ca2+ homeostasis as well as in water regulation. --------------------------------------------------------------------- [End CSM News, volume 5, number 9]