Search

 

PressCNRS international magazine

Table of contents

European Network of Excellence

Tadpole-Assisted Food Research

The Cascade(1) European Network of Excellence, now entering its fourth year, was created to assess the harmful effects that chemical contaminants in food products have on human health. Some 25 research

Some chemicals, present in food and drinking water, can disrupt our hormone systems by interacting with sex hormone receptors like estrogens or testosterone ones, as well as receptors for thyroid hormones. This can result in dysfunctions which, in the long run, could be implicated in a variety of conditions including obesity, cardiovascular disease, diabetes, impaired fertility, and certain types of cancer. Hence the need for a precise assessment of the health risks associated with these residues, especially since the European Reach regulations on chemical agents were implemented in June 2007.
With a budget of €14.4 million for five years (February 2004-January 2009), Cascade is a collaboration of over 250 scientists–molecular biologists, toxicologists, endocrinologists, chemists, nutritionists–from nine European countries.2 Their aim is to elucidate the molecular mechanisms of action of endocrine disrupters and develop high-performance screening tests.
One of these teams, led by Barbara Demeneix,3 has developed a novel method to detect these chemical agents. It is a “live” technique in that it uses “monitor” amphibians (tadpoles of Xenopus laevis frogs) that are genetically modified to produce fluorescent proteins under action of thyroid hormone. Perturbation of thyroid hormone signalling due to a chemical agent acting at the level of its receptor is detected by comparing normal induction of fluorescence produced by the hormone and perturbations induced by the molecule tested. Because of their aquatic and terrestrial life cycle, amphibians are particularly exposed and vulnerable to contaminants. “The modifications to the hormone balance triggered by the agent studied are revealed by the fluorescence of young, transgenic amphibians,” explains Jean-Baptiste Fini, a PhD student in the laboratory, who benefits from a Cascade grant. “This fluorescence is specific and quantifiable, as well as being very sensitive. Furthermore, the method is simple to use, relatively inexpensive, and fast–72 hours.” Within the Cascade framework, this method is being used to analyze the effects of bisphenol A (a plasticizer), vinclozoline (a pesticide) and genistein (a plant estrogen)–i.e., three of the four hormone disrupters chosen by the network as models (the fourth being tetrachlorodibenzo-p-dioxin). “We were the first European laboratory to have developed genetic tools to detect disruption of the thyroid or reproductive systems, and to integrate them in a living vertebrate model,” concludes Fini.
Bruno de La Perrière

 

tadpole

© S. le Mével

Transgenic tadpole subjected to bisphenol A, a plasticizer that disrupts thyroid hormone signaling.


Notes :

1. Chemicals as contaminants in the food chain: a network of excellence for research, risk assessment, and education.
For further information, visit: www.cascadenet.org/projectweb/portalproject/Index.html
2. Germany, Spain, Finland, France, Hungary, Italy, Netherlands, Slovakia, and Sweden.
3. Laboratoire “Évolution des régulations endocriniennes” (CNRS / Muséum national d'histoire naturelle).

Contacts :

Barbara Demeneix
Laboratoire “Évolution des régulations endocriniennes,” Paris.
demeneix@mnhn.fr


Top

Back to homepageContactcredits