CSM News Electronic Edition Volume 4, number 2 January 21, 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 through www.nwu.edu. ============================ Updated Database Available ============================ A new revised database and a new database update are now available via anonymous ftp from worms.cmsbio.nwu.edu [129.105.233.50]. The latest update is Update7 and contains 273 new references. Almost half of these were culled from Current Contents (through the last issue of 1994), and about 110 of the new references were obtained from the Loomis database as maintained by Del Richardson. Update7 can be added to Dicty3. The revised database is called Dicty4 and contains 5089 references. It is a thorough revision of Dicty3, and if you have not personalized the Dicty3 version, we suggest you download the new Dicty4 version in stead of adding Update7 to Dicty3. * Sixty-five refences were deleted (they were duplications or non-cellular slime mold papers), and 273 new references from Update7 were added. * Many corrections were made: no more D.d. or csm. * Page numbers are consistently p-pp, no more p,pp. * Journal abbreviations are now consistent, and with periods. * Titles are not capitalized. * Greek letter symbols have been spelled out because ASCII codes tended to corrupt some files. The references are now divided into 5 reference types: * journal articles * book chapters * books * theses * meeting abstracts. We are providing the new files in EndNote Plus and Refer/bibIX formats. We have discontinued distributing the Ref11 format since it appears that few have use for it. However, the original Ref11 v4.1 formatted file is still available for the asking. Each file format is recognized by a three letter extension: File EndNote Refer/bibIX --------------------------------------------------------------- UPDATE7 UPDATE7.END UPDATE7.BIX DICTY4 DICTY4.END DICTY4.BIX During the transfer, make sure that the ftp or the download protocol is set to BINARY. The files are large: dicty4.bix is 1.4 Mb; dicty4.end is 2.1 Mb. Additional technical notes can be found in a separate file called notes.txt in the same directory. If there are any problems with the downloading, let us know and we'll mail a floppy disk. Happy New Year, Jakob Franke and Ricky Sucgang =========== Abstracts =========== Evidence for a developmentally regulated pre-spore specific glutamine synthetase in the cellular slime mould Dictyostelium discoideum. Andrew J. Dunbar and John F. Wheldrake Flinders University of South Australia, Faculty of Science and Engineering, School of Biological Sciences, Bedford Park, Australia. Microbiology, in press. Abstract The enzyme glutamine synthetase (GS) has been described for the first time in Dictyostelium discoideum. The appearance of this enzyme is developmentally regulated. The level of activity is low in vegetative cells and increases more than three-fold during differentiation. Furthermore this enzyme has been shown to be differentially localised in prespore cells, the specific activity being approximately four-fold higher than in prestalk cells. The enzyme has an optimum pH of 7.8 and 8.2 in the glutamyltransferase and glutamylsynthetase assays respectively and an optimum temperature of 45 C. Kinetic studies of GS revealed apparent kms of 5.9 mM, 0.009 mM, and 8.6 mM for glutamine, ADP, and NH2OH respectively in the glutamyltransferase assay and 2.2 mM, 0.12 mM, and 0.64 mM for glutamate, ATP and NH2OH respectively in the glutamylsynthetase assay. ---------------------------------------------------------------------- Molecular genetic analysis of myoC, a Dictyostelium myosin I M.D. Peterson, K.D. Novak, M.C. Reedy, J.I. Ruman, and M.A. Titus Dept. of Cell Biology, Duke University Medical Center, Durham, NC 27710 J. Cell Sci., in press. Abstract: The protozoan myosin Is are widely expressed actin-based motors, yet their in vivo roles remain poorly understood. Molecular genetic studies have been carried out to determine their in vivo function in the simple eukaryote Dictyostelium, an organism that contains a family of four myosin Is. Here we report the characterization of myoC, a gene that encodes a fifth member of this family. Analysis of the deduced amino acid sequence reveals that the myoC gene encodes a myosin that is homologous to the well-described Acanthamoeba myosin Is as well as to Dictyostelium myoB and -D. The expression pattern of the myoC mRNA is similar to that of myoB and myoD, with a peak of expression at times of maximal cell migration, around 6 hours of development. Deletion of the myoB gene has been previously shown to result in mutant cells that are defective in pseudopod extension and phagocytosis. However, no obvious differences in cell growth, development, phagocytosis, or motility were detected in cells in which the myoC gene had been disrupted by homologous recombination. F-actin localization and ultrastructural organization also appeared unperturbed in myoC- cells. This apparent "lack" of phenotype in a myosin I single knockout cannot be simply explained by redundancy of function. Our results rather suggest that the present means of assessing myosin I function in vivo are insufficient to identify unique roles of these actin-based motors. --------------------------------------------------------------------- Codon usage, genetic code and phylogeny of Dictyostelium discoideum mitochondrial DNA as deduced from a 7.3 Kb region. Kiyohiko Angata, Kenji Kuroe, Kaichirou Yanagisawa and Yoshimasa Tanaka Institute of Biological Sciences, University of Tsukuba, Tsukuba, Ibaraki 305 Japan Current Genetics, in press. Abstract We have sequenced a region (7,376 bp) of the mitochondrial DNA (54 Kb) of the cellular slime mold, Dictyostelium discoideum. From DNA and amino-acid sequencecomparisons with known sequences, genes for ATPase subunit (ATP9), cytochrome (CYTB), dehydrogenase subunits 1, 3 and 6 (ND1, ND3 and ND6), small subunit rRNA (SSU rRNA) and seven tRNAs (Arg, Asn, Cys, Lys, f-Met, Met and Pro) have been identified. The sequenced region of the mt DNA has a high average A+T-content (70.8 %). The A+T-content of protein genes (73.6 %) is considerably higher than that DNA genes (61.3 %). Even with the strong A+T-bias, the genetic code is most probably the universal one. All 7 tRNAs are able to form typical clover leaf structures. The molecular phylogenetic trees of CYTB and SSU rRNA suggest that D. discoideum is closer to green plants than animals and fungi. ------------------------------------------------------------------- A group-I intron in the mitochondrial large-subunit ribosomal RNA-encoding gene of Dictyostelium discoideum: same site localization in alga and in vitro self-splicing Kiyohiko Angata, Shinji Ogawa, Kaichiro Yanagisawa and Yoshimasa Tanaka Institute of Biological Sciences, University of Tsukuba, Tsukuba, Ibaraki 305 Japan. Gene, in press. Abstract A 547-bp group-I intron belonging to subgroup IA1 was found near the 3'end of the large subunit ribosomal RNA-encoding gene (LSUrRNA) in the mitochondrial (mt) DNA of the cellular slime mold, Dictyostelium discoideum. This intron is inserted in a highly conserved stretch within the sequence that encodes the peptidyl transferase center domain V in the corresponding region of the Escherichia coli LSUrRNA. Interestingly, the insertion site of the intron is the same as that of the So.LSU.2 intron of the green alga, Scenedesmus obliquus, mt DNA and the Pw.LSU.2 intron of the colorless alga, Prototheca wickerhamii, mt DNA. The intron could self-splice in vitro at a concentration higher than 20 mM MgCl2. Polymerase chain reaction analysis showed the possible existence of an intron similar to that of D. discoideum LSUrRNA in another cellular slime mold, Polysphondylium pallidum (CK-8), but not in D. mucoroides (Dm7 and Dm11). ----------------------------------------------------------------- [End CSM News, volume 4, number 2]