CSM News Electronic Edition Volume 6, number 2 January 20, 1996 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" =================== PostDoc Available =================== An NIH funded postdoctoral position is available immediately. The start date is flexible and the position is for at least two years. Experience in molecular biology, biochemistry and cell biology would be an asset. Starting salary would be $23,000-$28,000 depending on experience. Projects in my laboratory primarily involve examining the molecular factors that regulate the endocytic and biosynthetic pathways to lysosomes. Current projects include 1) defining the roles of rab and rac GTPases in lysosomal trafficking, 2) characterizing phagosomes and the process of phagocytosis, and 3) localizing the domains in lysosomal enzymes containing lysosomal sorting signals. For all of these processes we use a variety of cell biological (including SEM, TEM and IF microscoy), biochemical and molecular genetic approaches. FOR FURTHER INFORMATION CONTACT JAMES CARDELLI DEPARTMENT OF MICROBIOLOGY AND IMMUNOLOGY LSU MEDICAL CENTER SHREVEPORT, LA 71130 PHONE 318 675-5756 FAX 318 675-5764 E-MAIL JCARDE@NOMVS.LSUMC.EDU =========== Abstracts =========== Competing Patterns of Signaling Activity in Dictyostelium discoideum Kyoung J. Lee, Edward C. Cox, and Raymond E. Goldstein Departments of Physics and Molecular Biology Princeton University, Princeton, NJ 08544} Phys. Rev. Letters, in press. Quantitative experiments are described on spatio-temporal patterns of coherent chemical signaling activity in populations of Dictyostelium discoideum amoebae. We observe competition between spontaneously firing centers and rotating spiral waves that depends strongly on the overall cell density. At low densities, no complete spirals appear and chemotactic aggregation is driven by periodic concentric waves, whereas at high densities the firing centers seen at early times nucleate and are apparently entrained by spiral waves whose cores ultimately serve as aggregation centers. Possible mechanisms for these observations are discussed. --------------------------------------------------------------------- Analysis of a tRNA Gene-Like Sequence (t-Element) with TTA at the Anticodon Position in the Mitochondrial DNA of Dictyostelium discoideum. Min Pi#, Kiyohiko Angata#, Toshimichi Ikemura@, Kaichiro Yanagisawa# and Yoshimasa Tanaka# #Institute of Biological Sciences, University of Tsukuba, Tsukuba, Ibaraki, 305 Japan @Department of Population Genetics, National Institute of Genetics, Mishima, Shizuoka, 411 Japan Journal of Plant Research, in press Abstract During the course of mitochondrial DNA sequencing of Dictyostelium discoideum, a sequence with a tRNA-like structure and two genes for tRNA Gln(UUG) and tRNA Trp(CCA) were found downstream of the gene for large subunit rRNA. The existence of tRNA Trp with CCA anticodon supports the finding that UGA codon is not a tryptophan codon in D. discoideum mitochondria. Interestingly, the tRNA gene-like sequence (t-element) has TTA at the anticodon position. Northern blot analysis showed that, in low molecular mass mitochondrial RNA fraction of growth-phase cells and developmental stage cells, a mature transcript of the element could not be detected in the tRNA region on a urea-denatured 5% polyacrylamide gel, although there were several bands in the higher molecular mass region, indicating the actual transcription of the t-element. Southern blot analysis for total and mitochondrial DNA showed that the element exists as a single copy, only in the mitochondrial DNA but not in the nuclear DNA. ------------------------------------------------------------------------ [End CSM-News, volume 6, number 2]