CSM News Electronic Edition Volume 2, number 9 February 26, 1994 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 [129.105.233.50], via Gopher at the same address, or by World Wide Web through WWW.acns.nwu.edu. The Continuing Saga of FM Medium --------------------------------- Jacob Franke writes: Wolfgang Nellen once asked us about the need for a commercial source of FM, the Dictyostelium defined minimal medium. I'm repeating his question: are you buying FM, or would you buy FM if the price was right? What's the right price, and how much would you buy? Lofstrand Labs, a small biotech company in Gaithersburg, MD, is willing to prepare FM, and sell it at the following prices: price/L 1-2 L $20.- 3-6 L $19.- 7-10 L $18.- 11 L or more $17.- But before preparing a batch they would like to have some assurance that there is a demand. Hence the questions. If I get a reasonable number of positive responses they are willing to invest a considerable sum in the ingredients and preparation of the medium. The medium will be tested by me. --------------------------------------------------------------------- Wolfgang Nellen writes: I was kind of surprised to see Jacob's message - we still get FM medium from GIBCO BRL at a lower price than the best conditions Jacob got (approx. $ 6/liter, supplied as a powder which is rather easy to handle). I also thought that people in the US were now getting it at the same or a similar price (except for Lenny Rome who cot the special offer of $600/ liter). At least our German sales rep knows the ins and outs of getting it and you might want to contact her if you have problems convincing your local GIBCO person that FM exists (Claudia Vogt, GIBCO - BRL, FAX: (++49) 721-78 04 99. --------------------------------------------------------------------- Del Richardson writes: We ordered FM from Gibco through Linda Parris, a rep that apparently works the south (and originally ordered some for Richard Gomer). Her number is 800/828-6686-1-6-6722 or (716) 773-0973. Gibco carries FM media in 5L pkgs under catalog # 074-90234N. They were charging $14.05 per pack for 5 packs and they estimated the freight and duty at ~$250 to $300 for our order. I tried to check the actual price, but apparently the billing has not gone through, even though the order was shipped last September. Apparently the stocks of FM are in Scotland (according to Wolfgang). ========== Abstracts ========== Aberrant pattern formation in myosin heavy chain mutants of Dictyostelium David Traynor@, Masao Tasaka#, Ikuo Takeuchi* and Jeffrey Williams The Imperial Cancer Research Fund, Clare Hall Laboratory, South Mimms, Herts., EN6 3LD, UK #Department of Botany, Faculty of Science, Kyoto University, Kyoto 606-1, Japan *National Institute for Basic Biology, Myodaiji, Okazaki 444, Japan @Present address: Department of Pharmacology, University of Cambridge, Tennis Court Road, Cambridge, CB2 1QT, UK Development, in press. Summary In mutant Dictyostelium strains which fail to accumulate the myosin heavy chain (MHC A) development is relatively normal up to the tight aggregate stage but is arrested prior to formation of the apical tip (DeLozanne and Spudich 1987, Knecht and Loomis, 1987). We show that in aggregates formed by such MHC A deficient (MHC A-) strains the proportions of pstA and pstB cells, the two prestalk cell types, and of prespore cells are similar to those found during normal development but their distribution is radically different. During the initial stages of normal slug formation pstA cells move to the tip, pstB cells accumulate in the base and prespore cells occupy the remainder of the aggregate. In the aggregates initially formed by MHC A- mutants pstA cells are present in a central core, pstB cells are present in the cortex and prespore cells lie sandwiched between them. Eventually, cells within the cortex differentiate into mature stalk cells but spores are never formed. Mixing experiments, in which MHC A- cells are allowed to co-aggregate with an excess of normal cells, show that MHC A- prestalk cells enter the aggregate relatively normally but are unable to enter the slug tip or to migrate into the stalk at culmination and that MHC A- prespore cells accumulate in the lower part of the spore head during culmination. Thus MHC A- cells appear to be able to move within the multicellular aggregate but are incapable of participating in normal morphogenesis. The structures formed by MHC A- cells are very similar to that of the agglomerates which form when wild type cells are developed in roller-tube culture, conditions that result in loss of the polarity imparted by the presence of an air-water interface. We propose formation of such a structure by mhc A- cells to be a default response, caused by their inability to undertake the shape changes and intercalatory cell movements that are necessary to form and extend the tip. ---------------------------------------------------------------------- Disruption of the gene encoding the EcmA, extracellular matrix protein of Dictyostelium alters slug morphology Alastair Morrison, Richard L. Blanton*, Mark Grimson *, Manuela Fuchs@, Keith Williams@ and Jeffrey Williams The Imperial Cancer Research Fund, Clare Hall Laboratory, South Mimms, Herts EN63LD. *Dept of Biol Sciences, Texas Tech University, Lubbock, Texas 79409-3131, USA. @ School of Biological Sciences, Macquarie University, Sydney, New South Wales 2109 Australia Develop. Biol., in press. Abstract The ecmA and ecmB genes of Dictyostelium are expressed in prestalk and stalk cells. They encode components of the slime sheath, the extracellular matrix that surrounds the migrating slug, and the stalk tube, the matrix that encases stalk cells. We have generated, by homologous gene disruption, a mutant in which the ecmB gene is inactivated but the strain develops normally. In contrast, ecmA null mutant strains develop to form abnormally long and thin standing slugs. While the slime sheath of mutant slugs appears to be normal in electron microscopic observations, the sheath material remaining on the substratum after the slug travels through it is abnormally susceptible to breakage. After a short period of migration the axial ratio of mutant slugs decreases to that of normal slugs and, at culmination, normal fruiting bodies are produced. These data suggest that the EcmA protein has its primary role during slug formation, where it contributes to the strength of the slime sheath, and that the function of the EcmB protein is dispensible. ---------------------------------------------------------------------- Inhibition of cAMP dependent protein kinase in Dictyostelium prestalk cells impairs slug migration and phototaxis John Bonner+ and Jeffrey Williams* +Department of Ecology and Evolutionary Biology, Princeton University, Princeton, N.J. 08544-1033, U.S.A. *ICRF Clare Hall, S. Mimms, Herts EN6 3LD UK Develop. Biol., in press. Summary Dictyostelium slugs expressing a dominant inhibitor of the cAMP dependent protein kinase (PKA) selectively in prestalk cells are insensitive to the environmental signals that normally induce culmination (Harwood, et al., 1992a). When such slugs do, eventually, attempt to culminate they are unable to activate stalk-specific gene expression and they become arrested in their development. We show here that they are also about half the size of normal slugs and that they move at about half normal speed, even after their size difference has been taken into account. They are also less accurate in orienting their direction of movement towards the light. Thus, in addition to its role in cellular differentiation, PKA is required for several important aspects of slug behaviour. ------------------------------------------------------------------ A role for cAMP dependent protein kinase in determining the stability of prespore cell differentiation in Dictyostelium. Neil A. Hopper and Jeffrey Williams The Imperial Cancer Research Fund, Clare Hall Laboratory, South Mimms, Herts EN6 3LD. UK Develop. Biol. in press. ABSTRACT When Dictyostelium slugs are disaggregated and shaken in suspension prespore mRNAs disappear from the cells very rapidly but in the presence of extracellular cAMP the loss of prespore mRNA sequences is retarded, (Barklis and Lodish, 1983; Mehdy et al, 1983, Mangiarotti et al, 1983). In a mutant which lacks a functional regulatory subunit of the cAMP dependent protein kinase (PKA), and where the catalytic subunit is thereby rendered constitutively active (Simon et al, 1992), two prespore mRNA sequences persist for extended times after cellular disaggregation. Thus PKA is a component of the signalling pathway that allows prespore cells rapidly to de-differentiate when extracellular cAMP signalling is disrupted. Analysis of cells expressing a dominant inhibitor of PKA shows there to be both a PKA requiring and a non PKA requiring intracellular signalling pathway directing prespore-specific gene transcription and suggests that that there may also be post-transcriptional regulation by PKA. --------------------------------------------------------------------- [End CSM News, volume 2, number 8]