Zebrafish as ecotoxicity sensors
Eawag News 64, June 2008
complete issue [pdf]
Editorial: Zebrafish – the aquatic mouse
Rik Eggen
Zebrafish as models
Martina Bauchrowitz
Around 8 years ago, research on zebrafish began in
the Environmental Toxicology -Department. Since then, an active team led by
molecular biologist Rik Eggen has been working with this new model organism.
Now the researchers have an opportunity to give an account of their work. [pdf]
Well looked after
Karin Rüfenacht and Kerstin Dannenhauer
About 600 zebrafish (Danio rerio) are kept in aquariums at Eawag. These
little creatures provide the fertilized fish eggs that are required on a daily
basis for ecotoxicology experiments. [pdf]
The MolDarT – a new toxicity test
Jane Muncke
Many toxicity tests involve the use of adult fish and take lethality as
the sole criterion for assessing the toxic effects of a substance, leaving the
underlying toxic mechanisms unclear. We have therefore developed a bioassay
that provides information on the molecular effects of toxicants – and does not
require the use of adult fish. [pdf]
Mysterious deformities in Lake Thun’s whitefish
Anja Liedtke
Since 2000, gonadal alterations have been observed in large numbers of
whitefish from Lake Thun. Despite intense research efforts, the causes of these
abnormalities have yet to be explained. Possible explanations include genetic
factors, pathogens and environmental pollutants. To test the pollutant
hypothesis, Eawag is using for the first time a zebrafish bioassay developed in
its own laboratories – as described in this progress report. [pdf]
Role of estrogens in organogenesis
Rik Eggen
In estrogen biosynthesis, the key enzyme is cytochrome P450 aromatase. It
catalyses the crucial step, i.e. the conversion of androgens to estrogens,
thereby determining estrogen concentrations. We used zebrafish to investigate
whether aromatase controls the development of the sex organs and the
lateral line. [pdf]
Estrogen receptor knockdown in zebrafish
Mirjam Fröhlicher
Estrogens, the female sex hormones, can only exert their effects when
they are recognized by estrogen receptors. But what happens if the production
of these receptors is suppressed? We studied this question with the aid of
knockdown zebrafish. A particularly striking feature of their behaviour was the
fact that they persistently swam in circles, lacking the lateral line organ
that zebrafish normally use to orient themselves. [pdf]
Estrogen-related actions of dioxins
Ksenia Groh
Dioxins are widespread pollutants. Like estrogens, these chemicals are
suspected to interfere with the hormonal system of wildlife. The reproduction
of fish, for example, is severely affected. To improve assessment of the risks
posed by these contaminants to the aquatic environment, we analyzed whether the
expression of a typically estrogen-controlled target gene might be modified by
dioxins. [pdf]
Effects of crude oil on zebrafish embryos
Jules Kemadjou
Oil disasters occur every few years. In most cases, the acute effects on
wildlife are dramatic. But even decades later, oil – or its water-soluble
components – remain in the aquatic environment and seem to be persistently
toxic. Our goal was therefore to assess the effects of oil on fish under
subacute conditions. Using zebrafish embryos as a model system, we were able to
identify hundreds of genes that showed altered expression on exposure to oil. [pdf]
Exposure to pollutants revealed by protein patterns
Marc Suter
Proteome analysis is not only a promising method in the medical field.
For almost 10 years, it has also been applied in environmental toxicology. This
approach reveals which proteins are induced or suppressed when organisms are
exposed to environmental pollutants. At Eawag, the method has now been
established for zebrafish. [pdf]
Forum
Eawag spin-off: sound management of surface runoff
New centre for applied ecotoxicology
In Brief