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MOLEKULARE
PARASITOLOGIE
Univ.-Doz. Mag. Dr. Julia Walochnik
A d r e s s e:
Kinderspitalgasse 15, A-1090 Wien
Tel: +43-1-40 490-79446
Fax.: +43-1-40 490-79435
Email: julia.walochnik@meduniwien.ac.at
ACHTUNG NEUE TELEFONNUMMER AB
19.11.2010
Tel: +43-1-40 160-38240
Fax.: +43-1-40 490-938233
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LEBENSLAUF:
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Seit 2008
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Vorstandsmitglied der Österreichischen Gesellschaft
für Biologische Systematik (NOBIS)
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Seit 2005
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Chefredakteurin der Österreichischen Gesellschaft für
Tropenmedizin und Parasitologie (ÖGTP)
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2004
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Habilitation zur Universitätsdozentin an der
Medizinischen Universität Wien
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2000
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Promotion zum Doktor der Naturwissenschaften (PhD) mit
Auszeichnung (Universität Wien)
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Seit 2003
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Vorstandsmitglied der Österreichischen Gesellschaft
für Tropenmedizin und Parasitologie (ÖGTP)
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1997
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Sponsion zur Magistra der Naturwissenschaften
(Universität Wien)
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Preise
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Österreichischer Hygienepreis 2002;
Gerhard-Piekarski-Preis
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MITARBEITERINNEN
Mag. Dr. Martina Köhsler Maternal leave
Maternal leave
Email: martina.koehsler@meduniwien.ac.at
Tel.: +43 1 4277 79482
DI Florian Astelbauer
PhD student, Anti-Protozoal and Anti-Fungal Activity of Plant Derived
Substances
Email: florian.astelbauer@meduniwien.ac.at
Tel.: +43 1 4277 79482
Mag. Ute Scheikl
Technician, Free-living amoebae in industrial waters
Email: u_scheikl@gmx.at
Tel.: +43 1 4277 79482
Sylvia Tippl
Diploma student, Antimicrobial agents in foam nests of tropical frogs
Email: sylviatippl@gmx.at
Tel.: +43 1 4277 79482
Susanne Glöckl
Maternal leave
Email: susanne.gloeckl@meduniwien.ac.at
Tel.: +43 1 4277 79449
Iveta Häfeli
Technician
Email: iveta.haefeli@meduniwien.ac.at
Tel.: +43 1 4277 79439
Jacek Pietrzak
Technician
Email: jacek.pietrzak@meduniwien.ac.at
Tel.: +43 1 4277 79449
Markus Kranzler
Diploma student, Mode of action of pentamycin agaist T. vaginalis
Email: a0347448@unet.univie.ac.at
Tel.: +43 1 4277 79482
Michael Syrowatka
Diploma student, Mode of action of pentamycin agaist T. vaginalis
Email: syrowatka_m@hotmail.com
Tel.: +43 1 4277 79482
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FORSCHUNG:
Classification and phylogeny of free-living amoebae
The free-living amoebae are ubiquitously occurring protozoans that feed on
bacteria, algae and yeasts. They are widely distributed in terrestrial and aquatic
habitats and have as a common feature that they are mitochondria bearing
eukaryotic unicellular microorganisms that produce pseudopodia (literally
“false feet”) protruding outward from the periphery of the cell
serving feeding and locomotion. Locomotion is performed by directed
cytoplasmic streaming and by rolling motion. Ingestion is linked very tightly
to locomotion and represents a typical phagocytosis, which is generated by an
exterior stimulus, cell-cell contact playing a major role. Most genera of the
free-living amoebae are characterised by a biphasic life cycle consisting of
a vegetative trophozoite stage and a persistant, physiologically static cyst
stage enabling them to withstand adverse environmental conditions. Some
genera show an additional flagellated dispersal form. The free-living amoebae
are highly abundant in the natural environment and serve significant roles at
the base of food webs. Moreover, they help to maintain the fertility of soils
by making nutrients available to plants. Bacteria and fungi grazing amoebae
are also of importance as biocontrol agents in both agriculture and forestry.
In addition to their important ecological functions, various representatives
of different genera of the free-living amoebae have been implicated in human
disease, however identification of species confronts with veritable
difficulties and the classification of the free-living amoebae is still
unresolved. The classification of the free-living amoebae is a most
contentious area and has been revised many times. The amoebae are asexually
propagating organisms. This implies a general discrepancy in species
determination, as the biological species is defined as a group of
interbreeding individuals that are reproductively isolated from other
organisms and is therefore not applicable on free-living amoebae. The
free-living amoebae subsummized under the taxon Rhizopoda represent an
eclectic assemblage of unicellular eukaryotes that use pseudopodia for
locomotion and feed by phagocytosis. It is now generally recognized that the
Rhizopoda are all but a monophylum and include highly diverse groups that
have evolved along many different lines. The presence of an amoeboid habit
undoubtedly represents a convergent evolution and is no longer considered to
be a conservative feature.
Because of the lack of fossil records in most protozoan groups including the
free-living amoebae the reconstruction of phylogeny has to be achieved by
comparing all available morphological, biochemical, and above all molecular
biological data of recent organisms and by searching for homologies.
Julia Walochnik
Susanne Glöckl
Jacek Pietrzak
COOPERATIONS
Dr. Rolf Michel, Ernst-Rodenwaldt-Institut, Koblenz, Germany
Encystment and excystment in Acanthamoeba castellanii: RNA and protein expression
in the differentiating cell
Differentiation processes such as the encystment are common in numerous
eukaryotic single cell organisms of which many are causative agents of human
infections. The cyst enables these microorganisms to endure adverse environmental
conditions and thus holds up the infectious cycle. In the ubiquitous genus
Acanthamoeba, which comprises potential pathogens causing Acanthamoeba
keratitis and granulomatous amoebic encephalitis, cysts are formed in
response to unfavourable environmental conditions including also biocide
treatment. Cysts surviving treatment lead to a more dramatic course of
disease or to recurrent infection and are also important for the vector role
of acanthamoebae.
Although Acanthamoeba castellanii has, due to its rapid growth and easily
inducible synchronous cell differentiation, been serving as a model organism
for studies on a variety of problems in cell biology for many decades, the
molecular mechanisms of Acanthamoeba encystment have not yet been elucidated.
However, the ability to form cysts is not only crucial for the role of
acanthamoebae as active and passive pathogens, but is of essential clinical
and ecological importance also in other pathogenic protozoa. Thus, a deeper
insight into this complex process is of extensive interest. It is the aim of
our project to apply contemporary molecular biological methodology to study
the encystment in A. castellanii and establish a model for protozoan cell
differentiation. Proteome analysis with two-dimensional polyacrylamide gel
electrophoresis (2D-PAGE) and subsequent genetic analysis will be applied to
elucidate the genetic and physiological key players involved in the
encystment and excystment processes of this organism. First, proteins that
are strongly expressed during differentiation will be isolated from 2D-gels,
identified and checked for regulatory sequences on the genetic level. With
regulatory sequences at hand, the A. castellanii genome will be searched for
other differentiation specific genes, including low copy proteins such as
transcriptional activators and repressors. This reverse genetic approach will
provide us with data on a large number of structural and regulatory genes,
thereby allowing the elucidation of A. castellanii differentiation. The Acanthamoeba
model will include the temporal and hierarchical order of expressed genes
that range from the induced early cyst to the mature cyst and will be the
basis for comparative studies including other cyst forming protozoan
pathogens as Entamoeba histolytica and Giardia lamblia. Moreover, the
influence of bacterial endocytobionts on Acanthamoeba castellanii encystment
will be assessed by RNA-profiling experiments based on the knowledge of the
genes involved in differentiation.
Julia Walochnik
Martina Köhsler
David Leitsch
COOPERATIONS
Univ.-Prof. Dr. Michael Duchêne, Medical University of Vienna: Department of
Specific Prophylaxis and Tropical Medicine Univ.-Prof. Dr. Günther Allmaier,
Technical University of Vienna: Department of Analytical Chemistry Univ.-Prof.
Dr. Matthias Horn, University of Vienna: Department of Microbial Ecology
this project is supported by the FWF
Identification of pathogenicity related proteins in Acanthamoeba spp.
Acanthamoebae are highly abundant in natural as well as in man-made habitats,
however, clinical manifestations of Acanthamoeba infections are rare.
Although Acanthamoeba keratitis (AK) and granulomatous amoebic encephalitis
(GAE) are highly divergent with respect to their immunobiologies, it has been
shown that in both infections host-parasite interactions play a crucial role
for the establishment of an infection. Yet the immunobiology of Acanthamoeba
infections is still poorly understood. In the current study we are focussing
on proteins involved in the establishment of an Acanthamoeba infection,
comparing virulent and non-virulent strains on one hand and AK and GAE
causing strains on the other.
Julia Walochnik
Wilawan Pumidonming
this project is supported by the ÖAD
Anti-Protozoal and Anti-Fungal Activity of Plant Derived Substances
Protozoans are the cause of widespread morbidity and mortality in many
countries of the world, including diseases such as malaria, sleeping
sickness, Chagas disease, amoebosis and leishmaniosis. Malaria alone causes
more than a million deaths and several hundred million cases of severe
disease each year. Unlike in several other diseases there are still no
vaccines on the market for any disease caused by protozoans, and very often
anti-protozoal agents are rather old drugs associated with severe
side-effects and/or problems of resistance.
This project aims to find new antiprotozoal natural compounds derived from
higher plants, focussing on bioactive substances occuring in tropical plant
families. Five different bioactive substances will be isolated and purified
and tested in vitro against different pathogenic protozoa and fungi. All five
substances have already shown anti-protozoal activity in preliminary tests
against Plasmodium falciparum, the causative agent of malaria, and Entamoeba
histolytica, the causative agent of amoebic dysentery or liver abscess.
Moreover, preliminary experiments have been performed against plant-pathogenic
species like Pyricularia grisea, Fusarium spp., Botrytis cinerea,
Pestalotiopsis spp. and Colletotrichum gloeosporioides.
In the first instance toxicity assays will be performed and substances will
be screened for potential genotoxicity. Subsequently, in vitro assays in
96-well plates will be developed in order to perform high throughput analysis
and substances will be tested against Entamoeba histolytica, Giardia
intestinalis, Leishmania donovani, Leishmania infantum, Plasmodium falciparum,
Plasmodium vivax, Toxoplasma gondii, Trichomonas vaginalis and Trypanosoma
cruzi.
Julia Walochnik
Florian Astelbauer
COOPERATIONS
Univ.-Prof. Dr. Michael Duchêne, Medical
University of Vienna: Department of Specific Prophylaxis and Tropical
Medicine Univ.-Prof. Dr. Harald Greger, University of Vienna:
Department of Phytochemistry Dr. Andreas Obwaller, Orphanidis Research GmbH
this project is supported
by the FFG
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