dictyNews
Electronic Edition
Volume 42, number 24
October 14, 2016
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Abstracts
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Terpene synthase genes in eukaryotes beyond plants and fungi:
Occurrence in social amoebae
Xinlu Chen, Tobias G. Kφllner, Qidong Jia, Ayla Norris,
Balaji Santhanam, Patrick Rabe, Jeroen Dickschat, Gad Shaulsky,
Jonathan Gershenzon, and Feng Chen
Department of Plant Sciences, University of Tennessee,
Knoxville, TN 37996
Max Planck Institute for Chemical Ecology, D-07745 Jena, Germany
Graduate School of Genome Science and Technology, University of
Tennessee, Knoxville, TN 37996
Graduate Program in Structural Computational Biology and Molecular
Biophysics, Baylor College of Medicine, Houston, TX 77030
Department of Molecular and Human Genetics, Baylor College of
Medicine, Houston, TX 77030
Kekulι-Institute of Organic Chemistry and Biochemistry, University
of Bonn, 53121 Bonn, Germany
PNAS, in press
Terpenes are structurally diverse natural products involved in many
ecological interactions. The pivotal enzymes for terpene biosynthesis,
terpene synthases (TPSs), had been described only in plants and fungi
in the eukaryotic domain. In this report, we systematically analyzed the
genome sequences of a broad range of nonplant/nonfungus eukaryotes
and identified putative TPS genes in six species of amoebae, five of
which are multicellular social amoebae from the order of Dictyosteliida.
A phylogenetic analysis revealed that amoebal TPSs are evolutionarily
more closely related to fungal TPSs than to bacterial TPSs. The social
amoeba Dictyostelium discoideum was selected for functional study of
the identified TPSs. D. discoideum amoebae grow as unicellular
organisms, whereas digesting bacteria and switch from vegetative growth
to multicellular development upon starvation. We found that expression of
most D. discoideum TPS genes was induced during development. Upon
heterologous expression, all nine TPSs from D. discoideum showed
sesquiterpene synthase activities. Some also exhibited monoterpene
and/or diterpene synthase activities. Direct measurement of volatile
terpenes in cultures of D. discoideum revealed essentially no emission
at an early stage of development. In contrast, a bouquet of terpenes,
dominated by sesquiterpenes including beta-barbatene and (E,E)-alpha-
farnesene, was detected at the middle and late stages of development,
suggesting a development-specific function of volatile terpenes in
D. discoideum. The patchy distribution of TPS genes in the eukaryotic
domain and the evidence for TPS function in D. discoideum indicate that
the TPS genes mediate lineage-specific adaptations.
submitted by: Gad Shaulsky [[log in to unmask]]
The Dictyostelium discoideum as a novel host system to study the
interaction between phagocytes and yeasts
Barbara Koller, Christin Schramm, Susann Siebert, Jαnos Triebel,
Eric Deland, Anna M. Pfefferkorn, Volker Rickerts and Sascha Thewes.
Front. Microbiol. 7:1665. doi: 10.3389/fmicb.2016.01665
The social amoeba Dictyostelium discoideum is a well-established model
organism to study the interaction between bacteria and phagocytes. In
contrast, research using D. discoideum as a host model for fungi is rare.
We describe a comprehensive study, which uses D. discoideum as a host
model system to investigate the interaction with apathogenic
(Saccharomyces cerevisiae) and pathogenic (Candida sp.) yeast. We
show that Dictyostelium can be co-cultivated with yeasts on solid media,
offering a convenient test to study the interaction between fungi and
phagocytes. We demonstrate that a number of D. discoideum mutants
increase (atg1-, kil1-, kil2-) or decrease (atg6-) the ability of the amoebae
to predate yeast cells. On the yeast side, growth characteristics, reduced
phagocytosis rate, as well as known virulence factors of C. albicans
(EFG1, CPH1, HGC1, ICL1) contribute to the resistance of yeast cells
against predation by the amoebae. Investigating haploid C. albicans
strains, we suggest using the amoebae plate test for screening purposes
after random mutagenesis. Finally, we discuss the potential of our
adapted amoebae plate test to use D. discoideum for risk assessment
of yeast strains.
submitted by: Sascha Thewes [[log in to unmask]]
The microfluidic lighthouse: an omnidirectional gradient generator
A. Nakajima (a), M. Ishida (b), T. Fujimori (b), Y. Wakamoto (a,b) and
S. Sawai (*a,b,c)
a Research Center for Complex Systems Biology, Graduate School of Arts
and Sciences, The University of Tokyo, Japan
b Department of Basic Science, Graduate School of Arts and Sciences,
The University of Tokyo, Japan
c PRESTO, Japan Science and Technology Agency, Japan
Lab Chip, 2016 (in press) DOI: 10.1039/c6lc00898d
Studies of chemotactic cell migration rely heavily on various assay systems
designed to evaluate the ability of cells to move in response to attractant
molecules. In particular, the development of microfluidics-based devices in
recent years has made it possible to spatially distribute attractant molecules
in graded profiles that are sufficiently stable and precise to test theoretical
predictions regarding the accuracy and efficiency of chemotaxis and the
underlying mechanism of stimulus perception. However, because the gradient
is fixed in a direction orthogonal to the laminar flow and thus the chamber
geometry, conventional devices are limited for the study of cell re-orientation to
gradients that move or change directions. Here, we describe the development
of a simple radially symmetric microfluidics device that can deliver laminar flow
in 360°. A stimulant introduced either from the central inlet or by photo uncaring
is focused into the laminar flow in a direction determined by the relative rate of
regulated flow from multiple side channels. Schemes for flow regulation and an
extended duplexed device were designed to generate and move gradients in
desired orientations and speed, and then tested to steer cell migration of
Dictyostelium and neutrophil-like HL60 cells. The device provided a high
degree of freedom in the positioning and orientation of attractant gradients,
and thus may serve as a versatile platform for studying cell migration,
re-orientation, and steering.
submitted by: Satoshi Sawai [[log in to unmask]]
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[End dictyNews, volume 42, number 24]
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