dictyNews
Electronic Edition
Volume 40, number 13
May 16, 2014
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Abstracts
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Potential role of bacteria packaging by protozoa in the persistence
and transmission of pathogenic bacteria
Alix M. Denoncourt1,2, Valérie E. Paquet1,2 and Steve J. Charette1,2,3*
1. Institut de Biologie Intégrative et des Systèmes (IBIS), Canada
2. Centre de recherche de l'institut universitaire en cardiologie et
pneumologie de Québec, Canada
3. Département de biochimie, microbiologie et bio-informatique,
Université Laval, Canada
Front. Microbiol. | doi: 10.3389/fmicb.2014.00240
(Hypothesis & theory article)
http://journal.frontiersin.org/Journal/10.3389/fmicb.2014.00240/abstract)
Many pathogenic bacteria live in close association with protozoa. These
unicellular eukaryotic microorganisms are ubiquitous in various environments.
A number of protozoa such as amoebae and ciliates ingest pathogenic
bacteria, package them usually in membrane structures, and then release
them into the environment. Packaged bacteria are more resistant to various
stresses and are more apt to survive than free bacteria. New evidence
indicates that protozoa and not bacteria control the packaging process. It
is possible that packaging is more common than suspected and may play
a major role in the persistence and transmission of pathogenic bacteria.
To confirm the role of packaging in the propagation of infections, it is vital
that the molecular mechanisms governing the packaging of bacteria by
protozoa be identified as well as elements related to the ecology of this
process in order to determine whether packaging acts as a Trojan Horse.
Submitted by Steve Charette [[log in to unmask]]
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Secondary Ion Mass Spectrometry Imaging of Dictyostelium discoideum
Aggregation Streams
J. Daniel DeBord1, Donald F. Smith2, Christopher R. Anderton3,
Ron M.A. Heeren2, Ljiljana Pasa-Tolc 3, Richard H. Gomer4, and
Francisco A. Fernandez-Lima1*
1Department of Chemistry and Biochemistry, Florida International
University, Miami, FL 33199, USA
2 FOM Institute AMOLF, Science Park 104, 1098 XG Amsterdam,
The Netherlands
3 Environmental Molecular Sciences Laboratory, Pacific Northwest
National Laboratory, Richland, Washington 99352, USA
4Department of Biology, Texas A&M University, College Station,
TX 77843, USA
PLoS ONE, in press
High resolution imaging mass spectrometry could become a valuable tool
for cell and developmental biology, but both, high spatial and mass spectral
resolution are needed to enable this. In this report, we employed Bi3
bombardment time-of-flight (Bi3 ToF-SIMS) and C60 bombardment Fourier
transform ion cyclotron resonance secondary ion mass spectrometry
(C60 FTICR-SIMS) to image Dictyostelium discoideum aggregation streams.
Nearly 300 lipid species were identified from the aggregation streams. High
resolution mass spectrometry imaging (FTICR-SIMS) enabled the generation
of multiple molecular ion maps at the nominal mass level and provided good
coverage for fatty acyls, prenol lipids, and sterol lipids. The comparison of
Bi3 ToF-SIMS and C60 FTICR-SIMS suggested that while the first provides
fast, high spatial resolution molecular ion images, the chemical complexity
of biological samples warrants the use of high resolution analyzers for
accurate ion identification.
Submitted by Richard Gomer [[log in to unmask]]
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Erika Kovacs-Bogdan , Yasemin Sancak , Kimberli J. Kamer , Molly
Plovanich , Ashwini Jambhekar , Robert J. Huber , Michael A Myre ,
Michael D Blower and Vamsi K. Mootha
Reconstitution of the mitochondrial calcium uniporter in yeast.
Proceedings of the National Academy of Sciences, USA in press
The mitochondrial calcium uniporter is a highly selective calcium
channel distributed broadly across eukaryotes but absent in the yeast S.
cerevisiae. In recent years, the molecular components of the human
uniporter holocomplex (uniplex) have been identified. It consists of three
membrane-spanning subunits (MCU, its paralogue MCUb, and EMRE)
and two soluble regulatory components (MICU1 and its paralogue MICU2).
At present, the minimal components sufficient for in vivo uniporter activity
are not known. Here, we consider Dictyostelium discoideum (Dd), a
member of amoebazoa, which is the outgroup of metazoa and fungi, and
show that it has a highly simplified uniporter machinery. We show that
D. discoideum mitochondria exhibit membrane potential-dependent
calcium uptake compatible with uniporter activity. Furthermore, expression
of DdMCU complements the mitochondrial calcium uptake defect in human
cells lacking MCU or EMRE. Moreover, expression of DdMCU in yeast
alone is sufficient to reconstitute mitochondrial calcium uniporter activity.
Having established yeast as an in vivo reconstitution system, we then
reconstituted the human uniporter. We show that co-expression of MCU
and EMRE is sufficient for uniporter activity, whereas expression of MCU
alone is not sufficient. Our work establishes yeast as a powerful in vivo
reconstitution system for the uniporter. Using this system we confirm that
MCU is the pore-forming subunit, define the minimal genetic elements
sufficient for a metazoan and a non-metazoan uniporter activity, and
provide valuable insights into the evolution of the uniporter machinery.
Submitted by Michael Myre [[log in to unmask]]
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[End dictyNews, volume 40, number 13]
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