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dictyNews Volume 31 Number 18
dictyNews
Electronic Edition
Volume 31, number 18
December 12, 2008
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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Folic acid is a potent chemoattractant of free-living amoebae in a new and
amazing species of a protist, Vahlkampfia
Yasuo Maeda1*, Taira Mayanagi2 and Aiko Amagai3
1Department of Developmental Biology and Neurosciences, Graduate School
of Life Sciences, Tohoku University, Aoba, Sendai 980-8578, Japan
2The Research Center for Child Mental Development, Osaka University
Graduate School of Medicine, Yamadaoka 2-2, Suita, Osaka 565-0871, Japan
3Department of Biomolecular Science, Graduate School of Life Sciences,
Tohoku University, Katahira 2-1-1, Aoba-Ku, Sendai 980-8577, Japan
Zoological Science, in press
Folic acid (folate; vitamin Bc) is well recognized as essential for the proper
metabolism of the essential amino acid methionine as well as for the synthesis
of adenine and thymine. A folate deficiency has been implicated in a wide
variety of disorders from Alzheimer’s disease to depression and neural tube
defects. In the cellular slime molds including Dictyostelium, vegetative
growth-phase cells are known to be chemotactically moved toward folate
that is secreted by bacterial food sources such as Escherichia coli.
Intracellular folate signal transduction including G proteins, Ca2+channels,
and PIP3 pathway has been reported in D. discoideum. To our surprise, the
genuine chemoattractant(s) of free-living protozoan amoebae have remained
to be determined, possibly because of a lack of a pertinent method for assaying
chemotaxis. We recently isolated a primitive free-living amoeba from the soil
of Costa Rica, and identified it as a new species of the genus Vahlkampfia
belonging to a subclass Gymnamoebia in which Entamoeba and Acanthamoeba
are included. The amoebae can grow and multiply quite rapidly engulfing nearby
bacteria such as E. coli. Importantly, we have demonstrated here using a quite
simple but finely designed chemotaxis assay that the Vahlkampfia amoebae
exhibit chemotaxis toward higher folate concentrations. Riboflavin and
cyanocobalamin were also found to serve as positive chemoattractants. Among
these chemoattractants , folate is of particular importance because its
function seems to be evolutionarily conserved as a potent chemoattractant
of amoeboid cells in a wide range of organisms as well as in the Protista
and cellular slime molds.
Submitted by: Yasuo Maeda [ymaeda@mail.tains.tohoku.ac.jp]
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Analysis of cell movement by simultaneous quantification of local membrane
displacement and fluorescent intensities using Quimp2.
Leonard Bosgraaf *, Peter J.M. van Haastert* and Till Bretschneider #
* University of Groningen, Cell Biochemistry Department, Haren, the Netherlands
# University of Warwick, Warwick Systems Biology Centre, Warwick, United Kingdom
Cell Motility and the Cytoskeleton, in press
The use of fluorescent markers in living cells has increased dramatically in
the recent years. The quantitative analysis of the images requires specific
analysis software. Previously, the program Quimp was launched for quantitating
fluorescent intensities at the membrane or the cortex of the cell. However,
Quimp it is not well suited to quantitate local membrane displacement. Here
we present Quimp2 that is capable of tracking membrane subregions in time,
which enables the simultaneous quantification of fluorescent intensities and
membrane movement. Quimp2 has two new tools, i) conversion filters to
analyze movies obtained with fluorescent, DIC and phase contrast different
microscopes, and ii) a macro that calculates the local membrane displacement
and provides various options to display the results. Quimp2 is used here to
investigate the molecular mechanism of cell movement by correlating the
dynamics of local membrane movement with the local concentration of
myosin and F-actin.
Submitted by: Peter J.M. van Haastert [p.j.m.van.haastert@rug.nl]
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[End dictyNews, volume 31, number 18]
