Schools of glowing fish could become a tool for monitoring water quality. The US government's National Institute of Environmental Health Services (NIEHS) has been funding research into fish that glow like a firefly when exposed to polluted water.Fireflies light up when an enzyme in their stomach called luciferase oxidises luciferin. The NIEHS hopes to insert luciferase-producing genes from fireflies into the eggs of zebrafish. Other genes would then be injected into the zebrafish making them sensitive to a particular pollutant. This could make the fish generate luciferase in the presence of mercury, for example.The genetically modified fish could then be dangled in a cage into water at risk of pollution. After half an hour they could be removed and dunked into a solution containing luciferin. If they start to glow, it means the water is polluted. The brightness of their glow could even reveal just how bad the pollution is. And the fish should survive the process for re-use later.
An US patent was claimed for this work and the abstract is as follows
The present invention provides methods and systems that uses transgenic zebrafish with an easily assessable reporter gene under the control of pollutant-inducible DNA response elements. Transgenic zebrafish, carrying pollution-inducible response elements, are placed in the water to be tested, and the contaminants become bioconcentrated (generally 1,000- to 40,000-fold, relative to the water) in the tissues of the fish thereby activating specific response elements, which up-regulate the LUC reporter gene. Fish are then removed from the test water and placed immediately in a luminometer cuvette and incubated with luciferin. Luciferin is rapidly taken up into the tissues of the fish, oxidized by luciferase, and light is produced. The luminescence is proportional to the environmental concentration of the pollutant (to which the fish had been exposed), which drives the expression of the LUC gene by means of the various DNA motifs. The luminescence is quantitated in the luminometer. In each response element-containing construct, a specific class of polluting chemicals, allowing for differential identification of pollutants in a complex mixture activates the expression of the LUC gene. This assay does not require killing the fish and allows for repeated analysis of the same site with the same fish. The sensitivity of the system can be manipulated by varying the sequence of the response element.
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