dictyNews Volume 26 Number 18

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dictyNews 
Electronic Edition 
Volume 26, number 18 
June 23, 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. 

 
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  Abstracts 
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Kin Preference in a Social Microorganism 

Natasha J. Mehdiabadi, Chandra N. Jack, Tiffany Talley Farnham,  
Thomas G. Platt, Sara E. Kalla, Gad Shaulsky, David C. Queller,  
and Joan E. Strassmann 

 
Nature, in press 

Kin recognition facilitates the evolution of cooperation and has been  
documented in many animals, but rarely in microorganisms. Here we show that  
the social amoeba Dictyostelium purpureum preferentially associates with kin  
during the social phase of its asexual lifecycle. By directing altruism  
towards relatives, D. purpureum should generally avoid the costs of  
chimerism seen in its congener D. discoideum.  

 
Submitted by: Natasha Mehdiabadi [njum@rice.edu] 
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The contractile vacuole in Ca2+-regulation in Dictyostelium: its essential  
function for cAMP-induced Ca2+-influx 

Dieter Malchow, Daniel F. Lusche, Christina Schlatterer, Arturo De Lozanne,  
Annette MŸller-Taubenberger 

 
BMC Developmental Biology, accepted 

Background: cAMP-induced Ca2+-influx in Dictyostelium is controlled by at  
least two non-mitochondrial Ca2+-stores: acidic stores and the endoplasmic  
reticulum (ER). The acidic stores may comprise the contractile vacuole  
network (CV), the endosomal compartment and acidocalcisomes. Here the role  
of CV in respect to function as a potential Ca2+-store was investigated. 

Results: Dajumin-GFP labeled contractile vacuoles were purified 7-fold by  
anti-GFP-antibodies in a magnetic field. The purified CV were shown for the  
first time to accumulate and release Ca2+. Release of Ca2+ was elicited by  
arachidonic acid or the calmodulin antagonist W7, the latter due to  
inhibition of the pump. The characteristics of Ca2+-transport and  
Ca2+-release of CV were compared to similarly purified vesicles of the ER  
labeled by calnexin-GFP. Since the CV proved to be a highly efficient  
Ca2+-compartment we wanted to know whether or not it takes part in  
cAMP-induced Ca2+-influx. We made use of the LvsA -mutant expected to  
display reduced Ca2+-transport due to loss of calmodulin. We found a severe  
reduction of cAMP-induced Ca2+-influx into whole cells. 

Conclusion: The contractile vacuoles in Dictyostelium represent a highly  
efficient acidic Ca2+-store that is required for cAMP-induced Ca2+-influx. 

 
Submitted by: Christina Schlatterer [Christina.Schlatterer@uni-konstanz.de] 
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[End dictyNews, volume 26, number 18]