- Veronika Sieber (Vet. med. Dissertation):Todesursachen
und Neurologische Krankheiten bei Hirschen aus Gatterhaltungen
in der Schweiz (abgeschlossen)
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Stefan Hoby: Investigations on the pathology
and steroid hormone related male biased parasitism in
wild ungulates in the National Park Hohe Tauern, Austria
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| In order to survey the health status of the wild ungulates
chamois, red deer, roe deer and ibex, a monitoring programme
was established in a part of the National Park Hohe Tauern.
From 2001 to 2004, tissues from different organs from
122 harvested animals were collected and examined histologically.
Histopathological changes are present particularly in
the respiratory and the gastro-intestinal tract, usually
in association with parasitological infections. Other
prominent findings include sarcoptic mange in chamois.
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| A second objective of the study is to elucidate the
impact of parasites on the structure of wild ungulate
populations. Males of vertebrate species tend to exhibit
higher rates of parasites than females. Sex-associated
hormones may influence immunocompetence and this may lead
to the male biased parasitism. We test this hypothesis
by correlating parasite load and steroid hormone levels
in chamois. Non-invasive methods are applied to assess
the endocrine and the parasite status of chamois, using
enzyme immunoassays (ELISA) for androgen, cortisol and
oestrogen metabolites from faecal samples. Male chamois
have a higher output of gastrointestinal eggs and lungworm
larvae compared to females. |
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The hypothesis of male biased parasitism
associated with gender-related hormone levels is confirmed
for the output of lungworm larvae and androgen and cortisol
metabolite levels, but not for the gastrointestinal nematodes.
Overall, gender differences in steroid levels appear to play
an important role in male biased parasitism, but other factors
including sex differences in behaviour, habitat choice, body
size and diet composition have to be considered.
This study is partly funded by the National Park Hohe Tauern.
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| Valéria Café Marçal:
Myelopathy in cheetah |
| The world's fastest land animal, Acinonyx
jubatus (cheetah), is now an endangered species,
and listed in Appendix I of the Convention of International
Trade in Endangered Species (CITES). The Cheetah’s
genetic inbreeding has led to low survivorship with greater
susceptibility to diseases, specially to certain viruses.
Amongst the neurological diseases, a progressive degenerative
disorder of unknown aetiology called cheetah myelopathy
is at present the most frequently described disease known
to affect captive cheetahs within the European Endangered
Species Program (EEP) population. |
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| Cheetah, dorsal tract spinal cord, 20x (MBP stain) |
The cause of this disease has not been
yet determined. This study aims to evaluate and better characterize
the histopathological lesions of myelopathy in cheetah. To
this end, mainly immunohistochemical methods are applied.
The results will provide a broader understanding of the pathogenesis
of this disease.
This study is partly funded by the Zoological Garden Basel.
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| Helena Nimmervoll: Mange in free-ranging
wildlife in Switzerland - epidemiology and pathology |
| Sarcoptic mange is a skin disease occurring in over
100 species, including man. Being a highly contagious
disease, it is considered a threat to endangered wildlife
species (e.g. the lynx) and a risk to healthy animal populations.
Until now, little is known about the mange situation in
Switzerland. The aim of this project is to analyze the
distribution of mange (mainly in fox) in Switzerland and
to assess factors of relevance for mange epidemiology.
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In-depth investigations on disease infestation and
symptoms are performed in four selected regions (cantons BE,
FR, GE and VS). Animals sent from these areas are examined
pathologically, and mites are sampled for genetic analyses.
Other factors (season, climate, sex, etc) possibly influencing
the infestation are taken into consideration.
This study is part of a project funded by the Swiss Federal
Agency for the Environment, Forests and Landscape (BUWAL)
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| Richard Burki: Endocrine disruption
in brown trout from Swiss rivers: Assessment of estrogenic
exposure and effects |
| There is concern over anthropogenic substances
in the aquatic environment that have the potential to
disrupt the normal functioning of the endocrine system
of fish. The objective of this thesis is to investigate
endocrine, in particular estrogenic, disruption in brown
trout, Salmo trutta. |
Exposure of brown trout to estrogen-active substances
in Swiss midland rivers is assessed by analysing the biomarker
vitellogenin. Effects of estrogen-active substances on
brown trout are studied with respect to sexual differentiation
and to the response to parasite infections. Developing
brown trout are exposed over different time periods to
estrogens, and the consequences on gonad differentiation
and expression of aromatase, a key enzyme in sex differentiation,
are determined. Further, using the causative agent of
the proliferative kidney disease, the myxzoan parasite
Tetracapsuloides bryosalmonae, as an example, the question
is addressed whether estrogen exposure is able to modulate
prevalence and intensity of the disease.
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| This study is part of the project SAFE
funded by the National Research Programme 50 “Endocrine
Disruption”. |
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| Kathrin Bettge: The Proliferative Kidney
Disease of salmonids: dynamics of the parasite in the
fish host |
| The Proliferative Kidney Disease (PKD) is an emerging
disease in Switzerland, which can cause massive mortalities
in infected fish populations. The causative agent of PKD
is the myxozoan parasite, Tetracapsuloides bryosalmonae.
To date, neither the life cycle of the parasite nor the
factors being involved in parasite-induced mortality are
understood. The objectives of the thesis are to study
(a) the proliferation of the parasite in the fish host,
(b) how this proliferation depends on environmental conditions,
(c) how the parasite proliferation correlates with kidney
pathology and fish mortality, and (d) if the parasites
are able to leave the fish or if the fish is a dead-end
host. |
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| The diagnostic methods used for these investigations
include histopathology, immunohistochemistry, in-situ
hybridisation and real-time PCR. |
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| Evangelia Kallivretaki: Functional significance
of aromatase in embryonic development and sexual differentiation
of zebrafish |
Estrogen plays a role in the organization
of the developing nervous and reproductive systems of
vertebrates. A key enzyme in the process of estrogen synthesis
is aromatase, the product of the cyp19 gene, which is
responsible for the production of estrogens from aromatizable
androgens. In zebrafish, there are two forms of aromatase.
Cyp19a1 is predominant in the gonads, while cyp19a2 shows
highest expression in the brain. The thesis examines the
differential role of the two aromatase isoforms in the
ontogeny of the neuronal and gonadal systems of zebrafish.
To this end, a variety of tools including immunohistochemistry,
in situ hybridization, and morpholino knock-down have
been developed. To assess the functional significance
of aromatase in embryos, the effect of aromatase knockdown
on the development of neuromasts and retina is studied.
The role of aromatase expression in goand differention
will be studied by correlating the individual Cyp19a1
and Cyp19a2 levels to the individual gonad differentiation
stage. The various parameters are analysed both in control
zebrafish and zebrafish exposed to endocrine-disrupting
substances.
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Acridine Orange staining of 4dpf zebrafish embryos.
a: control (uninjected fish)
b: cyp19a1 morphant fish
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| This study is part of the project XEBRA
funded by the National Research Programme 50 “Endocrine
Disruption”. |
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| Michael Wenger: Use of molecular techniques
to assess fish health under complex exposure scenarios |
Chemical contamination can pose a threat
to the health of fish populations. In order to evaluate
whether fish in its habitat is impacted by contaminants,
it needs a) detection whether significant exposure takes
place, b) identification of the nature of the chemicals
the fish is exposed to, and c) understanding of the interaction
between chemical stressors and other stressors such as
pathogens. An established approach to assess chemical
exposure of fish is the use of toxicant-inducible biomarkers,
for instance CYP1A for dioxin-like substances, vitellogenin
for substances activating the estrogen receptor pathway,
or histopathology as an integrative stress indicator.
The aim of the present thesis is to built on existing
biomarkers, but to explore additionally the potential
of multigene technologies. Emphasis will be given to complex
exposure situations, where both toxicants and pathogens
are present.
This study is part of the EU-funde project MODELKEY. |
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| PCR for Vitellogenin (lanes 1 & 2) and CYP1A (lanes
3 & 4) |
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My Khong Thi: Serological studies on
the dynamics of virus infections in fish
An investigation in the years 2000/2001 on the status
of viral diseases in feral and farmed fish in Switzerland
revealed a low prevalence of VHS-infected animals, as
detected by means of virus isolation or RT-PCR, but a
high prevalence of fish expressing anti-VHS-antibodies,
as detected by serological methods. |
| These contrasting findings lead to the relationship
between virus infection and serological responses. Therefore,
the thesis aims a) to follow the kinetics of serum antibody
expression in virus-infected fish, and b) to compare
different serological detection methods (ELISA, SPNT)
in order to evaluate to what extent the serological
results are method-dependent. In addition to VHS, also
IHN will be investigated.
This study is part of a project funded by the Swiss
Federal Agency for Veterinary Affairs (BVET)
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Ziele und Aufgaben