Dicty News
Electronic Edition
Volume 9, number 16
December 13, 1997

Please submit abstracts of your papers as soon as they have been
accepted for publication by sending them to dicty@nwu.edu.

Back issues of Dicty-News, the Dicty Reference database and other useful
information is available at the Dictyostelium Web Page 
"http://dicty.cmb.nwu.edu/dicty/dicty.html"

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 Abstracts
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Cloning and sequence analysis of the cDNA encoding the elongation 
factor-1b of Dictyostelium discoideum

Soo-Cheon Chae and Yasuo Maeda *

Biological Institute, Graduate School of Science, Tohoku University, 
Aoba, Sendai 980-77, Japan

Biochim. Biophys. Acta, in press

Abstract

   A cDNA encoding elongation factor-1b (DdEF-1b) for protein synthesis 
was isolated from Dictyostlium discoideum cells by the differential 
display (DD) method. The DdEF-1b cDNA sequence with a length of 733 
bp encodes a protein (Mr. 24.1 kDa) consisting of 214 amino acids. 
Comparison of the predicted amino acid sequence revealed relatively 
high homology to that of DdEF-1b from silkworm (59%), human (57%) and 
Xenopus (55%). Northern analysis showed that the DdEF-1b mRNA is 
maximally expressed during the vegetative growth phase, followed by 
marked decrease in response to cell differentiation induced by 
starvation.

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MAP Kinase Function in Amoeboid Chemotaxis

Yiwen Wang, Joey Liu, and Jeffrey E. Segall
Department of Anatomy and Structural Biology

Albert Einstein College of Medicine, 1300 Morris Park Avenue
Bronx, NY 10461

J. Cell Science, in press

Summary

   Mutants lacking the MAP kinase DdERK2 show reduced chemotactic 
responses to folate and cAMP.   Analysis of cAMP chemotaxis shows 
that Dderk2- cells are defective in chemotaxis to high concentrations 
of cAMP.  This defect is due to an inability to repolarize in the 
continued presence of high concentrations of cAMP.  Under these 
conditions, the speed of movement of mutant cells remains low.  
Instead of generating a leading pseudopod, mutant cells generate 
transient crown-like structures over multiple regions of the cell 
surface.  These structures differ from pseudopods in that they 
contain myosin II as well as F actin and coronin.   These studies 
identify a role for MAP kinases in coordinating the formation of 
cell projections generated in response to chemoattractants.

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[End Dicty News, volume 9, number 16]