Dicty News
Electronic Edition
Volume 20, number 4
March 15, 2003

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

Back issues of Dicty-News, the Dicty Reference database and other 
useful information is available at DictyBase--http://dictybase.org.

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

Unexpected roles of a Dictyostelium homologue of eukaryotic EF-2 in growth 
and differentiation

Sohsuke Watanabe, Kohji Sakurai, Aiko Amagai and Yasuo Maeda* Department 
of Developmental Biology and Neuroscience, Graduate School of Life 
Sciences, Tohoku University, Sendai 980-8578, Japan

*Author for correspondence (e-mail: ymaeda@mail.cc.tohoku.ac.jp)

J. Cell Sci. (in press)

Summary

EF-2 is believed to be indispensable for polypeptide chain elongation in 
protein synthesis, and therefore for cell proliferation.  Surprisingly, 
we could isolate ef2 null cells from Dictyostelium discoideum which 
exhibited almost normal growth and protein synthesis, suggesting the 
existence of another molecule capable of compensating for EF-2 function. 
The knock-out of Dictyostelium EF-2 (Dd-EF2H; 101 kDa phosphoprotein) 
impairs cytokinesis , resulting in formation of multinucleate cells. The 
initiation of differentiation including the acquisition of aggregation-
competence was delayed in Dd-ef2 null cells compared to wild-type. In 
contrast, Dd-ef2 overexpression enhanced the progression of 
differentiation, thus indicating a positive involvement of Dd-EF2H in 
growth/differentiation transition. 

----------------------------------------------------------------------------

A linear dominance hierarchy among clones in chimeras of the social 
amoeba, Dictyostelium discoideum.

Angelo Fortunato, David C. Queller, & Joan E. Strassmann 
Department of Ecology and Evolutionary Biology, Rice University, PO 
Box 1892, Houston, Texas, 77251-1892, USA 

Journal of Evolutionary Biology, in press

Abstract 

Amoebae from different clones of Dictyostelium discoideum aggregate into 
a common slug, which migrates towards light for dispersal, then forms a 
fruiting body consisting of a somatic, dead stalk, holding up a head of 
living spores. Contributions of two clones in a chimera to spore and 
stalk are often unequal, with one clone taking advantage of the other's 
stalk contribution. To determine whether there was a hierarchy of 
exploitation among clones, we competed all possible pairs among seven 
clones and measured their relative representation in the prespore and 
prestalk stage and in the final spore stage. We found a clear linear 
hierarchy at the final spore stage, but not at earlier stages. These 
results suggest that there is either a single principal mechanism or 
additive effects for differential contribution to the spore, and that 
it involves more than spore/stalk competition.


----------------------------------------------------------------------------

[End Dicty News, volume 20, number 4]