An increasing number of previously "safe" chemicals have now been found to be capable of disrupting the endocrine system. Pollution caused by endocrine disruptors, especially estrogenic disruptors, is threatening the health of wildlife and humans, and is becoming one of the most serious environmental problems worldwide. Developing a reliable method for accurate and prompt detection of estrogenic activity is a priority.
From today (March 5) to July 11, the Hong Kong Science Museum has a new exhibition, "Transgenic Fish for Rapid Monitoring of Estrogenic Pollution", which introduces the transgenic brackish medaka fish strain developed by a research group led by Associate Professor of the Department of Biology and Chemistry at City University of Hong Kong, Dr Shuk Han Cheng. This fish can sensitively detect the presence of estrogenic endocrine disruptors and can produce varying intensities of green fluorescence to reflect the estrogenic activity level.
Endocrine disruptors, also called environmental hormones, are exogenous substances that alter the functions of the endocrine system and consequently affect an intact organism, or its progeny, or (sub) populations. Such disruptors include natural hormones, man-made hormones (e.g. oral contraceptives, drugs used in hormone-replacement treatment and some animal feed additives), and man-made chemicals which include thousands of new and existing man-made chemicals that can disrupt a human's endocrine system. Such chemicals may be designed for uses in industry (e.g. industrial solvents and lubricants), in agriculture (e.g. certain pesticides), and in many everyday products (e.g. certain food and beverage containers, food-can liners, food wraps, plastic bottles, plastic tableware, food additives, detergents, cosmetics and drugs).
The endocrine disruptors may enter our body through ingestion, inhalation or dermal contact and cause many health problems, ranging from developmental malformation, reproductive organ tissue abnormality and even cancers (e.g. breast cancer, ovary cancer, testicular cancer) to precocious puberty, obesity, poor semen quality, infertility, and social problems such as skewed sex ratio.
By combining the choriogenin H gene (estrogen-sensitive and liver-specific) found in medaka fish and a green fluorescent protein (GFP) gene, the City University constructed a highly estrogen-sensitive artificial gene that can produce fluorescent protein. The gene was successfully transferred into the genome of medaka. In the presence of estrogen or estrogenic endocrine disruptors, the transgenic medaka fish will express this modified gene and synthesise green fluorescent protein in the liver.
This assay is very simple. Just expose transgenic larval fish to a test solution such as environmental water samples or a water solution added with the substance under test for 12 to 24 hours, and then check the induced green fluorescence protein expression in fish liver under a fluorescence microscope. The quantity of expressed green fluorescence protein directly correlates to estrogenic endocrine disruptor concentration and exposure time, and can be quantified by measuring fluorescence intensity.
In addition to the high sensitivity and ease of use, this method is also fast and very economic. The technique can be used for rapid monitoring of estrogenic activity of different brands of soymilk as well as ingredients of cosmetics separately and in combination. Its applications may extend to monitoring the estrogenic activity of Pearl River and Hong Kong coastal waters in the future. The idea to use transgenic fish to monitor estrogenic pollutants can be further applied to develop other transgenic organisms to monitor other kinds of pollutants such as androgenic endocrine disruptors, heavy metals and toxins.
To complement the exhibition, a video "Transgenic Fish Technology" provided by the State Key Laboratory in Marine Pollution of City University, and an interview with Dr Lo Wing-lok on "Estrogen and Health", will be screened at the "Science Window" of the Science News Corner. The Science Web will also provide a list of relevant websites to enhance audiences' knowledge about the topics introduced.
The Science Museum is located at 2 Science Museum Road, Tsim Sha Tsui East. It opens from 1pm to 9pm from Monday to Wednesday and on Fridays, and from 10am to 9pm on Saturdays, Sundays and public holidays. It is closed on Thursdays (except public holidays). Admission is $25 with half-price concession for full-time students, people with disabilities and senior citizens aged 60 or above. Admission is free on Wednesdays.
For enquiries, call 2732 3232 or visit the Science Museum's website at http://hk.science.museum.
Ends/Friday, March 5, 2010