Zebra Fish as Pollution Indicators
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
Associate 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 biodegradable
and economical to breed. 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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