CSM News Electronic Edition Volume 1, number 24 December 4, 1993 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. =========== Abstracts =========== Optical flow analysis of the ventral cellular layer of the migrating Dictyostelium discoideum slug. Edmond J. Breen(1) and Keith L. Williams(2) (1) Present address:CSIRO Division of Mathematics and Statistics, Institute of Information Science and Engineering, Locked Bag 17, North Ryde, N.S.W., 2113, Australia (2) School of Biological Sciences, Macquarie University, North Ryde, N.S.W., 2109, Australia Journal of General Microbiology, in press. Summary: A digital image analysis system for extracting motion information from time-varying digital light microscopy images is presented. This system is then used to map out the movement profile of the surface layer of cells in contact with the substratum through the extracellular matrix (ECM) of the migrating D. discoideum slug. From digital high magnification light microscopy images, the morphology of moving cells within the tail region of a young migrating wild Type WS380B slug is described, and compared with the morphology of streaming D.discoideum cells. It is shown that: 1) when the migrating tip of the slug touches the agar substrate, cells in the anterior ventral surface layer of the tip region slow dramatically; 2) overall cell movement in the ventral surface layer of the migrating D. discoideum slug is slower than the movement of the slug as a whole and 3) in less than 10% of cases a wave of movement (groups of cells synchronously slowing down and then accelerating forward) propagates down the slug axis at approx. 1.2um/s. The time interval between waves may be related to the time interval between tip-to-substratum contact that is periodically reestablished during normal WS380B slug migration after each aerial projection of the tip. ---------------------------------------------------------------------- Dictyostelium prespore-specific gene (Dp87) encodes a sorus matrix protein Hajime Nakao(1), Akitugu Yamamoto(2), Ikuo Takeuchi and Masao Tasaka(3) National Institute for Basic Biology, Myodaiji, Okazaki 444, Japan 1. Laboratory of Cell Engineering, Department of Insect Genetics and Breeding, National Institute of Sericultural and Entomological Science, Tsukuba, Ibaraki 305, Japan 2. Kansai Medical University, Moriguchi, Osaka 570, Japan 3. Author for correspondence at present address: Department of Botany, Facult of Science, Kyoto University, Kyoto 606-01, Japan J. Cell Sci., in press Summary In this paper, we report on the characteristics of the product of a prespore-specific gene (Dp87) of Dictyostelium discoideum. Polyclonal antibody was made against a bacterially synthesized Dp87-encoded protein fragment. Using this antibody, the product was characterized by immunochemical and immunocytological methods. It was shown that the Dp87-encoded protein is a prespore-specific protein with a molecular mass of 83kD, which first appears at the standing slug stage and persists in mature fruiting bodies. Western blot studies revealed the presence of an additional 81kD protein prior to the appearance of 83kD protein from the tipped aggregate to the standing slug stage, thus indicating the former to be a precursor protein. Immunocytochemical and immunoelectronmicroscopical studies showed that the protein is bound to ER at the early stages of development when only 81kD protein is present. At the later stages when 83kD protein predominates, however, the protein becomes localized in prespore vacuoles (PSVs) and is associated with the inner fibrous material of PSVs, but not with the peripheral membranous material. This is in contrast to spore coat proteins which are localized in PSVs from the beginning of their appearance and associated with both structures of PSVs. In mature fruiting bodies, most Dp87 protein is localized to the interspore space (matrix) of the sori, with some left on the surface of the stalk tube. Disruptants of the Dp87 gene were also produced. Although they contained neither 81kD nor 83kD protein, they showed no phenotypic defects as compared to the parental strain. ---------------------------------------------------------------------- [[End CSM-News.v1.#24]]