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dictyNews Volume 29 Number 02
dictyNews
Electronic Edition
Volume 29, number 2
July 13, 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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Induction of cAMP signaling and spore differentiation in
Dictyostelium development by a novel protein, DIA2
Kaori Hirata, Aiko Amagai, Soo-Cheon Chae , Shigenori Hirose¤ and
Yasuo Maeda*
Department of Developmental Biology and Neurosciences, Graduate School of
Life Sciences, Tohoku University, Aoba, Sendai 980-8578, Japan
*Author for correspondence
Present address: Department of Pathology, Wonkwang University, Iksan-shi,
Chonbuk 570-749, South Korea
¤Present address: Departments of Molecular and Human Genetics, Biochemistry
and Molecular Biology, Baylor College of Medicine, Houston, TX 77030, USA
Differentiation, in press
The novel gene dia2 (differentiation-associated gene 2) was originally
isolated as a gene expressed specifically in response to initial
differentiation of Dictyostelium discoideum Ax-2 cells. Using dia2AS cells
in which the dia2 expression was inactivated by the antisense RNA method,
DIA2 protein was found to be required for cAMP signaling during cell
aggregation. During late development, the DIA2 protein changed its location
from the endoplasmic reticulum (ER) to prespore-specific vacuoles (PSVs)
that are specifically present in prespore cells at the slug. In
differentiating prestalk cells, however, DIA2 was found to be nearly lost
from the cells. Importantly, exocytosis of PSVs from prespore cells and the
subsequent spore differentiation were almost completely impaired in dia2AS
cells. In addition, spore induction by externally applied 8-bromo cAMP was
significantly suppressed in dia2AS cells. Taken together these results
strongly suggested that DIA2 might be closely involved in cAMP signaling
and spore differentiation as well as in the initiation of differentiation
during Dictyostelium development.
Submitted by: Yasuo Maeda [ymaeda@mail.tains.tohoku.ac.jp]
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Toward the structure of dynamic membrane-anchored actin networks:
an approach using cryo-electron tomography.
Guenther Gerisch1 and Igor Weber2
1Max-Planck-Institut fuer Biochemie, Am Klopferspitz 18a, D-82152 Germany
2Rudjer Boskovic Institute, Bijenicka cesta 54, P.O.B.180, 10002 Zagreb,
Croatia
Cell Adhesion & Migration, in press
In the cortex of a motile cell, membrane-anchored actin filaments assemble
into structures of varying shape and function. Filopodia are distinguished
by a core of bundled actin filaments within finger-like extensions of the
membrane. In a recent paper by Medalia et al. [1] cryo-electron tomography
has been used to reconstruct, from filopodia of Dictyostelium cells, the
3-dimensional organization of actin filaments in connection with the plasma
membrane. A special arrangement of short filaments converging toward the
filopodÕs tip has been called a Òterminal coneÓ. In this region force is
applied for protrusion of the membrane. Here we discuss actin organization
in the filopodia of Dictyostelium in the light of current views on forces
that are generated by polymerizing actin filaments, and on the resistance
of membranes against deformation that counteracts these forces.
Submitted by: Guenther Gerisch [Cgerisch@biochem.mpg.de]
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[End dictyNews, volume 29, number 2]
