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dictyNews Volume 23 Number 12
Dicty News
Electronic Edition
Volume 23, number 12
October 08, 2004
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 Dicty-News, the Dicty Reference database and other
useful information is available at dictyBase - http://dictybase.org.
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Abstracts
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Behavior of cellular slime molds in the soil
J. T. Bonner
D. S. Lamont
Department of Ecology and Evolutionary Biology, Princeton University,
Princeton, New Jersey 08544
Mycologia, in press
The cellular slime molds are soil organisms, yet ever since they were
discovered in 1869 they have been studied on agar surfaces. Here the
behavior of a number of species is examined and it is evident that they
have different responses to directional light and they all thrive in the
presence of soil. While phototaxis clearly plays a significant role in
their ability to come to the soil surface for dispersal, even more important
are gradients in the soil: both temperature gradients known from earlier
studies, and as we show here, gas gradients-presumably ammonia as a repellent
and oxygen as an attractant. There are numerous differences in both
morphology and behavior among slime mold species, some of which are likely
to be the result of natural selection to particular habitats, while others
could more easily be explained by neutral phenotypic variation.
Submitted by: John Bonner [jtbonner@Princeton.EDU]
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Changes in spatial and temporal localization of Dictyostelium homologues of
TRAP1 and GRP94 revealed by immuno-electron microscopy
Hitomi Yamaguchi*, Tsuyoshi Morita**, Aiko Amagai, and Yasuo Maeda1
Department of Developmental Biology and Neurosciences, Graduate School of
Life Sciences, Tohoku University, Aoba, Sendai 980-8578, Japan
Present address: *Department of Cell Genetics, National Institute of
Genetics, Mishima, Shizuoka-ken 411-8540, Japan. **Department of
Neuroscience (D13), Osaka University Graduate School of Medicine, Yamadaoka
2-2, Suita City, Osaka 565-0871, Japan.
Exp. Cell Res., in press
TRAP1 (tumor necrosis factor receptor-associated protein 1) is a member of
the molecular chaperone HSP90 (90-kDa heat shock protein) family. In this
study, we mainly examined the behavior of Dictyostelium TRAP1 homologue,
Dd-TRAP1 during Dictyostelium development by immuno-electron microscopy. In
vegetatively growing D. discoideum Ax-2 cells, Dd-TRAP1 locates in nucleolus
and vesicles in addition to the cell cortex including cell membrane. Many of
Dd-TRAP1 molecules moved to the mitochondrial matrix in response to
differentiation, though Dd-TRAP1 on the cell membrane seems to be retained.
Some Dd-TRAP1 was also found to be secreted to locate outside the cell
membrane in Ax-2 cells starved for 6 h. At the multicellular slug stage,
Dd-TRAP1 was primarily located in mitochondria and cell membrane in both
prestalk and prespore cells. More importantly, in differentiating prespore
cells a significant number of Dd-TRAP1 locates in the PSV (prespore-specific
vacuole) that is a sole cell type specific organelle and essential for spore
wall formation, whereas some Dd-TRAP1 in the cell cortical region of
prestalk cells. These findings strongly suggest importance of Dd-TRAP1
regulated temporally and spatially during Dictyostelium development.
Incidentally, we also have certificated that the glucose-regulated protein
94 (Dd-GRP94) is predominantly located in Golgi vesicles and cisternae,
followed by its colocalization with Dd-TRAP1 in the PSV.
Submitted by: Yasuo Maeda [ymaeda@mail.tains.tohoku.ac.jp>]
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A brilliant monomeric red fluorescent protein to visualize cytoskeleton
dynamics in Dictyostelium
Markus Fischer 1, Ilka Haase 1, Evelyn Simmeth 2, Guenther Gerisch 2, and
Annette Mueller-Taubenberger 2
1 Lehrstuhl fuer Organische Chemie und Biochemie
Technische Universitaet Muenchen
Lichtenbergstr. 4, D-85747 Garching, Germany
2 Max-Planck-Institut fuer Biochemie
Am Klopferspitz 18, D-82152 Martinsried, Germany
FEBS Letters, in press
Red fluorescent proteins (RFPs) combined with GFP are attractive probes for
double-fluorescence labeling of proteins in live cells. However, the
application of these proteins is restrained by stable oligomer formation and
by their weak fluorescence in vivo. Previous attempts to eliminate these
problems by mutagenesis of RFP from Discosoma (DsRed) resulted in the
monomeric mRFP1, and in the tetrameric RedStar RFP, which is distinguished
by its enhanced fluorescence in vivo. Based on these mutations we have
generated an enhanced monomeric RFP, mRFPmars, and report its spectral
properties. Together with green fluorescent labels, we used mRFPmars to
visualize filamentous actin structures and microtubules in Dictyostelium
cells. This enhanced RFP proved to be suitable to monitor the dynamics of
cytoskeletal proteins in cell motility, mitosis, and endocytosis using
dual-wavelength fluorescence microscopy.
Submitted by: Annette Mueller-Taubenberger [amueller@biochem.mpg.de]
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[End Dicty News, volume 23, number 12] 
