dictyNews Volume 27 Number 15

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dictyNews 
Electronic Edition 
Volume 27, number 15 
November 24, 2006 

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 dictyNews, the Dicty Reference database and other 
useful information is available at dictyBase - http://dictybase.org. 

 
========= 
  Abstracts 
========= 

 

A model for cell type localization in the migrating slug of Dictyostelium  
discoideum based on differential chemotactic sensitivity to cAMP and  
differential sensitivity to suppression of chemotaxis by ammonia 

Ira N Feit*, Jeffrey Pawlikowsky, and Caroline Zawilski 

Franklin and Marshall College, Lancaster, PA 17603 USA 

*Correspondence: Ira N. Feit (Ira.Feit@fandm.edu) 

 
Journal of Biosciences, in press 

The three basic cell types in the migrating slug of Dictyostelium  
discoideum show differential chemotactic response to cAMP and  
differential sensitivity to suppression of the chemotaxis by ammonia.  
The values of these parameters indicate a progressive maturation of  
chemotactic properties during the transdifferentiation of slug cell types.  
We present a model that explains the localization of the three cell types  
within the slug based on these chemotactic differences and on the  
maturation of its chemotactic properties. 

 
Submitted by: Ira N. Feit (Ira.Feit@fandm.edu) 
-------------------------------------------------------------------------------- 

 
Proteomic and micro-array analyses of the Dictyostelium Zak1-GSK-3  
signalling pathway reveals a role in early development 

Lana Strmecki1, Gareth Bloomfield2, Tsuyoshi Araki3, Emma Dalton4,  
Jason Skelton5, Christina Schilde3, Adrian Harwood4, Jeffrey G.  
Williams3, Al Ivens5 and Catherine Pears1 

1. Biochemistry Department, Oxford University, South Parks Road,  
Oxford OX1 3QU UK 
2. MRC Laboratory of Molecular Biology, Hills Road, Cambridge,  
CB2 2QH, UK 
3. School of Life Sciences, Wellcome Trust Biocentre, University of  
Dundee, Dundee DD1 5EJ, UK 
4. Cardiff School of Biosciences, Cardiff University, Museum Avenue,  
Cardiff, CF10 3US 
5. The Wellcome Trust Sanger Institute, Wellcome Trust Genome  
Campus, Hinxton, Cambridge, CB10 1SA, UK 

 
Eukaryotic Cell, in press.  

GskA, the Dictyostelium GSK-3 orthologue, is modified and activated by  
the dual-specificity tyrosine kinase Zak1 and the two kinases form part  
of a signalling pathway that responds to extracellular cAMP. We identify  
potential cellular effectors for the two kinases by analysing their null  
mutants. There are proteins and mRNAs that are altered in abundance in  
only one or other of the two mutants, indicating that each kinase has some  
unique functions. However, proteomic and micro-array analysis respectively  
identified a number of proteins and genes that are similarly mis-regulated in  
both mutant strains. The positive correlation between the array data and the  
proteomics data is consistent with the Zak1-GskA signalling pathway  
functioning by directly or indirectly regulating gene expression. The discoidin  
1 genes are positively regulated by the pathway while the abundance of the  
H5 protein is negatively regulated. Two of the targets, H5 and discoidin 1, are  
well-characterised markers for early development, indicating that the Zak1- 
GskA pathway plays a role in development earlier than previously observed.  

 
Submitted by: Catherine Pears [pears@bioch.ox.ac.uk] 
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[End dictyNews, volume 27, number 15]