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]