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Wednesday, May 6, 2015, 09:06

Something fishy in our product testing

By Wang Yuke

A new technology developed by an HK-based enterprise using genetically modified fish embryos to detect toxins in food and other products is making waves internationally. Wang Yuke reports.

Something fishy in our product testing
Vitargent Chief Technology O fficer Chen Xueping and founder Eric Chen (first and second from right) receive an award from the Hong Kong government on April 28. (Parker Zheng / China Daily)

Hidden toxins in food and other everyday consumer products may come to light before causing health hazards, thanks to a solution developed by a Hong Kong bioscience company, Vitargent.

Vitargent employs genetically-modified fish embryos to discover, potentially, thousands of toxic additives harmful to human health.

The World Health Organization reports that contaminated food is associated with deaths of an estimated 2 million people annually around the world.

Hormones are mixed into the feed of cattle, hogs and poultry as a matter of routine, to accelerate growth. The growth hormones in animal feed are passed down the food chain, and are known to increase the incidence of reproductive disorders in humans, the WHO found in 2012.

Vitargent’s director said the company’s innovation is capable of reforming the existing scientific testing system and improve the global food safety standard.

“Both fish and human beings are sensitive to many similar toxins. The difference is that fish have a shorter response time,” says Eric Chen, founder and director of Vitargent.

In humans, it takes 10 to 20 years for serious effects of toxic materials consumed in foods to emerge — manifesting as cancer, cardiovascular diseases and degenerative conditions.

We cannot afford to wait 20 years to see if certain chemicals can cause cancer. By then it could be too late, the American Cancer Society has concluded.

The impact of harmful chemicals on fish embryos, however, is immediate. When the living environment is askew, the development of fish embryos goes awry, so that they develop physical defects, stop growing, and some die.

Winning the big prize

The genetically-engineered embryos have proven capable of identifying the presence of any of the 1,000 toxins at a time, compared with fewer than 10 by traditional methods.

“When we test cooking oil, we normally target aflatoxins (highly toxic compounds linked to liver cancer), heavy metals, benzopyrene (a carcinogen tied to lung cancer) and detergent. But we probably don’t expect plasticizer (used as an additive used occasionally to increase liquidity of materials) in the oil sample,” says Chen Xueping, chief technology officer of the company. “When we find the amounts of aflatoxins, heavy metals and benzopyrene are lower in sum than the total level of toxicity, we know there must be some other toxins needing to be identified. Then we turn to chemical analysis to track down the existence of plasticizer.”

The invention of the modified embryos earned the Grand Prix at the 43rd International Exhibition of Inventions of Geneva in April.

The team developed two types of fish embryos, each to serve a different purpose. One breed, called Medaka, detects estrogen-like substances in cosmetics, pesticides, dairy products, meat, seafood and nutritional supplements. Estrogen extracts are added to skin cream and hair care products — products advertised as enhancements to skin elasticity and hair thickness. But long-term exposure to estrogen has led to early puberty in girls, and upset fertility cycles in mature women, preventing them from getting pregnant.

Unwitting consumption of excess estrogen hidden in food and water has led countless people to suffer from infertility every year, said Chen.

The Medaka fish embryos in the Vitargent testing undergo genetic engineering in preparation for use. Researchers extract the DNA of green fluorescent protein from jellyfish, modify the DNA to make it more stable and inject it into Medaka genome.

Chen Xueping explains hormones can prompt the release of proteins in embryos, called a gene expression. As the protein in the embryos becomes observable, the Medaka embryos, when exposed to estrogen-related compounds, turn fluorescent green under the microscope.

Using immature embryos for food testing is acceptable under international law.

Before the test, researchers must pre-treat solid samples, to inoculate Medaka embryos with liquefied samples in three different concentrations.

Chen Xueping explains varying the concentration of suspected contaminated samples helps minimize errors. “We put in eight embryos, not one or two, to minimize eccentric reactions based on individual differences. Some embryos may be sensitive to certain substances, while some may not. So ‘eight’ is a safe bet.”

Prior to testing, the Medaka embryos are stored in an incubator for 24 hours. The intensity of the green coloration is directly proportional to the degree of toxicity.

The second modified embryo is taken from the Zebra fish — which exhibits developmental defects when exposed to toxic materials. Zebra fish, says Chen Xueping, closely approximate the metabolic activity of human beings, developing an edema — a fluid build-up causing a tumor-like swelling – in contact with toxins.

Also tails of the Zebra fish tend to curl when exposed to toxins in water.

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