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dictyNews Volume 28 Number 18

dictyNews
Electronic Edition
Volume 28, number 18
June 22, 2007
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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Dihydrodictyopyrone A and C: New members of dictyopyrone family
isolated from Dictyostelium cellular slime molds.
Kikuchi H*, Nakamura K, Kubohara Y, Gokan N, Hosaka K, Maeda Y, & Oshima Y*.
*Corresponding authors
Graduate School of Pharmaceutical Sciences Tohoku University, Japan
Tetrahedron Lett. In press.
Abstract
We have explored the diversity of secondary metabolites produced by
cellular slime molds to evaluate if they are valuable resources for
biologically potential substances. From the methanol extract of
fruiting bodies of Dictyostelium firmibasis, we obtained new
alpha-pyranoids, dihydrodictyopyrone A (1) and C (2). Compounds
1 and 2 are new members of the dictyopyrone family, which are
characteristic secondary metabolites of various species of
Dictyostelium cellular slime molds.
Submitted by: Yuzuru Kubohara [kubohara@showa.gunma-u.ac.jp]
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An information-theoretic characterization of the optimal gradient sensing response
of cells
Burton W. Andrews and Pablo A. Iglesias
Department of Electrical and Computer Engineering
The Johns Hopkins University, Baltimore, MD 21218
PLoS Computational Biology, Accepted
Abstract
Many cellular systems rely on the ability to interpret spatial heterogeneities
in chemoattractant concentration to direct cell migration. The accuracy of
this process is limited by stochastic fluctuations in the concentration of
the external signal and in the internal signaling components. Here we use
information theory to determine the optimal scheme to detect the location
of an external chemoattractant source in the presence of noise. We compute
the minimum amount of mutual information needed between the chemoattractant
gradient and the internal signal to achieve a prespecified chemotactic accuracy.
We show that more accurate chemotaxis requires greater mutual information.
We also demonstrate that a priori information can improve chemotaxis efficiency.
We compare the optimal signaling schemes to existing experimental measurements
and models of eukaryotic gradient sensing. Remarkably, there is good quantitative
agreement between the optimal response when no a priori assumption is made about
the location of the existing source, and the observed experimental response of
unpolarized D. discoideum cells. In contrast, the measured response of polarized
D. discoideum cells matches closely the optimal scheme assuming prior knowledge
of the external gradient - for example, through prolonged chemotaxis in
a given direction. Our results demonstrate that different observed classes of
responses in cells (polarized and unpolarized) are optimal under varying
information assumptions.
Submitted by: [Pablo Iglesias <pi@jhu.edu]
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[End dictyNews, volume 28, number 18]