dictyNews
Electronic Edition
Volume 33, number 8
September 25, 2009

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Announcement:

In del Álamo et al. (2007), PNAS 104 no. 33, 13343-13348 we described an 
improved Fourier traction cytometry algorithm that allows the calculation of 2D 
traction forces from the 2D deformations of an elastic substrate. We are 
making it available as a software package which can be found at 
http://maeresearch.ucsd.edu/~jalamo/dynacyte. 

Ruedi Meili

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


Differentiation inducing factors in Dictyostelium discoideum: a novel low 
molecular factor functions at an early stage(s) of differentiation

Akiko A. Oohata1*, Masashi Fukuzawa2, Rie Hotta3, Manabu Nakagawa4, 
Masatake Niwa3 and Yoshiaki Takaya3 

1Biological Laboratory and 4Chemical laboratory, Kansai Medical University, 
Hirakata, Osaka 573-1136, Japan 
2 Department of Biology, Faculty of Agriculture and Life Science, Hirosaki 
University, Hirosaki, Aomori 036-8561, Japan
3 Faculty of Pharmacy, Meijo University, Tempaku, Nagoya 468-8503, Japan


Devel. Growth & Differ., in press

There are reports that secreted factor(s) are involved in prespore cell 
differentiation in Dictyostelium discoideum, but the structures and functions of 
the various factors have not been elucidated. Previously, we described two 
prespore cell-inducing factors in conditioned medium; one was a glycoprotein 
named prespore-cell inducing factor (ψ factor, or PSI-1), and the other 
a heat stable, dialyzable factor(s).  In this paper, we purified and characterized 
the most potent prespore-cell inducing activity in dialysates. The factor began 
to be secreted after the onset of starvation and stopped being secreted once 
the cells had aggregated, which was earlier than the onset of psi factor gene 
expression.  In addition, unlike psi factor, its secretion did not appear to 
depend on activation of protein kinase A. Interestingly, the purified factor 
not only induced prespore-cell specific genes such as pspA and cotC but 
also a prestalk-cell specific gene, ecmB in vitro. The purified factor is 
tentatively designated polyketide like factor (PLF), because it seems to be 
a novel polyketide with mol wt 208.  Half maximal induction of prespore cell 
was obtained with 26 nM of PLF.  We propose that PLF plays a key role in 
the acquisition of differentiation commitment, before the psi factor induces 
specifically prespore cell differentiation.


Submitted by Akiko Oohata [oohata@makino.kmu.ac.jp]
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[End dictyNews, volume 33, number 8]