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Scientists from the NUS Department of Biological Sciences are developing a breed of zebra fish that can detect water pollutants by changing colours


 

Genetically-engineered zebra fish: luminating beauties with practical applications

Scientists from the NUS Department of Biological Sciences are developing a breed of zebra fish that can detect water pollutants by changing colour. The team of biologists, headed by Assoc Professor Gong Zhiyuan, aims to produce commercially viable zebra fish that can be used as pollutant indicators. This transgenic fish, bred successfully through genetic engineering, is a simple alternative to complicated pollutant-testing systems.

Zebra fish are usually black and silver in colour. Through genetic manipulation, A/P Gong has produced a few varieties that radiate green or red fluorescent colour.

The fluorescent genes are extracted from jellyfish and then injected into zebra fish eggs. With these genes, the body of the zebra fish is capable of giving off a fluorescent glow. In order to trigger off the genes in the fish to be of any use, inducible gene promoters are used to act as control switches to activate different tissues on the fish.

So far, the researchers have succeeded in isolating two types of gene promoters in the zebra fish -- an estrogen-inducible promoter and a stress-responsive promoter. These promoters have been used to drive the fluorescent colour genes in transgenic zebrafish. Such fluorescent-coloured transgenic fish will be able to respond to the presence of chemicals like oestrogen through the estrogenic promoter and heavy metals and toxins through the stress-responsive promoter. The fish will immediately display the colour depending on the type of environment the colour has been specified for.

Although only red and green colours have been produced in the zebra fish, A/P Gong revealed that he could add up to as many as five colours to the zebra fish, each colour to indicate a different pollutant. In using such transgenic fish, pollutants can be detected with one quick look. The fish are also economical to breed and biodegradable. All these factors make them very suitable pollutant indicators.

Besides zebra fish, ornamental marine species such as the carp and goldfish can also be genetically engineered to display different fluorescent colours. The team is also working towards producing fish that give off a different coloured glow depending on water temperatures. This may lead to the use of fluorescent fish as temperature indicators.

 
         
 
 
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