Dicty News Electronic Edition Volume 23, number 15 November 5, 2004 Please submit abstracts of your papers as soon as they have been accepted for publication by sending them to dicty@northwestern.edu or by using the form at http://dictybase.org/db/cgi-bin/dictyBase/abstract_submit. Back issues of Dicty-News, the Dicty Reference database and other useful information is available at dictyBase - http://dictybase.org. ============= Abstracts ============= The Calcineurin Inhibitor Gossypol Impairs Growth, Cell Signalling and Development in Dictyostelium discoideum Barbara Weissenmayer, Katrina B�ckeler, Angela Lahrz and Rupert Mutzel Institut f�r Biologie - Mikrobiologie, Fachbereich Biologie, Chemie, Pharmazie, Freie Universit�t Berlin, K�nigin-Luise-Strasse 12-16, 14195 Berlin, Germany FEMS Microbiology Letters, in press The Dictyostelium genome harbors single copy genes for both the catalytic and regulatory subunits of the Ca2+/calmodulin-dependent protein phosphatase calcineurin. Since molecular genetic approaches to reduce the expression of these genes have failed so far, we attempted to pharmacologically target calcineurin activity in vivo by using the recently described calcineurin inhibitor, gossypol. Up-regulation of expression of the gene for the Ca2+-ATPase PAT1 in conditions of Ca2+ stress was reduced by gossypol. Dictyostelium wild-type cells treated with 12.5 to 100 �M gossypol showed reduced growth rates and impaired development. In addition, cell signalling was affected. A cell line that overproduces the catalytic subunit of calcineurin was more resistant to gossypol. Submitted by: Barbara Weissenmayer [bweiss@zedat.fu-berlin.de] ----------------------------------------------------------------------------- Nuclear Pore Complex Structure and Dynamics revealed by Cryoelectron Tomography Martin Beck, Friedrich F�rster, Mary Ecke, J�rgen M. Plitzko, Frauke Melchior, G�nther Gerisch, Wolfgang Baumeister and Ohad Medalia Max Planck Institute of Biochemistry, D-82152 Martinsried, Germany Science, in press. Nuclear pore complexes (NPCs) are gateways for nucleocytoplasmic exchange. To analyse their structure in a close-to-life state, we studied transport-active, intact nuclei from Dictyostelium discoideum by means of cryoelectron tomography. Subvolumes of the tomograms containing individual NPCs were extracted in silico and subjected to three-dimensional classification and averaging, whereby distinct structural states were observed. The central plug/transporter (CP/T) was variable in volume and could occupy different positions along the nucleocytoplasmic axis, supporting the notion that it essentially represents cargo in transit. Changes in the position of the CP/T were accompanied by structural rearrangements in the NPC scaffold. Submitted by: Wolfgang Baumeister [baumeist@biochem.mpg.de] and Ohad Medalia [omedalia@biochem.mpg.de] ============================================================================== [End Dicty News, volume 23, number 15]