dictyNews Volume 23 Number 15

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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. 

 

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  Abstracts 
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The Calcineurin Inhibitor Gossypol Impairs Growth, Cell Signalling and 
Development in Dictyostelium discoideum 

Barbara Weissenmayer, Katrina Bšckeler, Angela Lahrz and Rupert Mutzel 

Institut fŸr Biologie - Mikrobiologie, Fachbereich Biologie, Chemie, 
Pharmazie, Freie UniversitŠt Berlin, Kšnigin-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 µM 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] 

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Nuclear Pore Complex Structure and Dynamics revealed by Cryoelectron 
Tomography 
  
Martin Beck, Friedrich Fšrster, Mary Ecke, JŸrgen M. Plitzko, Frauke 
Melchior, GŸnther 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] 

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[End Dicty News, volume 23, number 15]