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A fish to detect contaminant endocrinal disruptors (24/09/2012)

 

A test in fish that allows us to detect the endocrinal disrupting effects of certain contaminants in the environment has just been developped by the researchers from INERIS and Inserm.

Fluorescence seen in the brain of the fish embryo, induced by the expression of gene cyp19a1b bound to the GFP.

A team managed by Olivier Kah in Inserm unit 1085 "Institut based their work on a gene that expresses in the brain, and that reacts strongly to certain endocrinal disruptors. In order to make it easier to measure this gene, they used a fluorescent reporter gene. By using the embryos of zebrafish that are transparent, we can see the effects in the brain when the embryos are exposed to disruptor pollutants. The results of these works are published in the review Plos One (1).

Over the last 20 years, numerous studies have proved the harmful effects of artificial compounds on the reproductive capacity of organisms. Certain pollutants (nonylphenols, bisphenol A, pesticides, pharmaceutical residues, etc.) present in surface water, industrial waste or sediments are capable of mimicking the effects of oestrogens. They thus modify the biological processes that are controlled by oestrogens and are involved in the reproduction and growth functions of organisms, with potentially harmful consequences for the health of living creatures and their progeny. Such substances are known as "endocrinal disruptors" (ED).

Pollutants with oestrogen activity also affect the brain.
The originality of the work carried out by the Inserm and INERIS researchers resides in the fact that the study of endocrinal disruptors concentrates on a gene that expresses only in the brain, and demonstrates the sensitivity of the nervous system to pollutants.
The results obtained by the researchers confirm that in the fish embryo, a certain number of substances affect the activity of the stem cells in the brain, cells that are vital to the development of the central nervous system. This effect is seen in the expression of a specific gene in the brain that is extremely sensitive to oestrogens: gene cyp19a1b.

Based on these observations, the INERIS and Inserm teams developed a test to detect oestrogen activity in a transgenic fish model. This transgenic zebrafish model (2) helps to identify the effect of pollutants on an enzyme from gene cyp19a1b, aromatase, that is responsible for the synthesis of oestrogens in the body.

The brain of the fish embryos uses a fluorescent reporter known as GFP (Green Fluorescent Protein), that renders it fluorescent when exposed to substances that mimic oestrogens.

21 components (e.g. natural or synthetic oestrogens; alkylphenols, bisphenols) of the 45 tested induced varying degrees of fluorescence. The metabolic capabilities of the model allowed us to detect substances such a certain androgens and certain synthetic progestatives (used in the contraceptive pill).

A test of this type is helpful in evaluating chemical substances, as required by the REACh (3) regulation. This tool is a complement to the existing in-vitro systems, and it has the advantage of integrating what will happen to pollutants in the body and of taking account of their metabolism, something than cannot always be done using tests on cells. Given its sensitivity, it could also be used to monitor aquatic environments.

The INERIS and Inserm researchers have finally opened up new prospects in the field of study of endocrinal disruptors in the central nervous system.

For the researchers themselves, it appears that this simple, robust and sensitive test will have many fields of application in assessing the risks implied in oestrogenic endocrinal disruptors.

Footnotes:
(1) Brion (F.), Le Page (Y.), Piccini (B.), Cardoso (O.), Tong (S.K.), Chung (B.C.), Kah (O.). Screening Oestrogenic Activities of Chemicals or Mixtures In Vivo Using Transgenic (cyp19a1b-GFP) Zebrafish Embryos. PLoS One, 2012, 7(5):e36069, Epub 2012 May 7.
(2) In collaboration with Professor B.C. Chung of the Academia Sinica in Taiwan.
(3) Registration, Evaluation, Authorisation and Restriction of Chemical substances: European Parliament rule and directive No. 1907/2006 of December 18, 2006, concerning the registration, evaluation and authorization of chemical substances and the restrictions applicable to these substances.

For more information
French National Institute for Environmental Technology and Hazards

(MDN)

 


L'armadietto omeopatico casalingo
(del Dott. Turetta)
Quali sono i problemi o le disfunzioni che possono giovarsi di un intervento omeopatico d'urgenza e, di conseguenza, come dovrebbe essere un ideale armadietto medicinale omeopatico casalingo.


A cura di: Dott.ssa S.Cavalli, Dott. L. Colombo, Dott. U. Zuccardi Merli
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