A SMALL black-and-silver-striped fish is promising to open the door to understanding human diseases.

THIS ZEBRA IS EARNING ITS STRIPES: So why is the zebrafish a favourite among genetic scientists, with about 500 groups in the world studying it? About 7,000 of the zebrafish's markers have been found to match human genes, and while not all genes are alike, similar genes in the fish correspond to those in humans and these swing into action during certain processes. The fact that it develops its major organs within 24 hours of fertilisation also makes it a popular object for study.

Biologists at Singapore's Institute for Molecular and Cell Biology studying the zebrafish have scored a coup - they have identified and isolated 15,000 of its unique genetic markers after two years of work.

These markers act as tags for genes and their presence on a chromosome indicates the position of a gene.

Knowing this allows scientists to monitor how the gene works, its reactions to external stimuli and mutations.

They hope that their work on the fish's genes can help scientists understand how human ones work, as there is some genetic similarity between the two.

So far, a rough analysis of the 15,000 markers have revealed that about 7,000 match human genes.

While not all genes are alike, similar genes in the fish correspond to those in humans and this set of genetic material swings into action during certain processes, like the development of blood cells.

The scientific world is agog over the work and more than 40 laboratories in universities round the world have asked the institute for samples of the markers for their own research.

Dr Peng Jinrong, principal investigator with the institute's Functional Genomics Laboratory, and molecular biologist Wen Zilong led the team working on the project.

The potential of the zebra- fish, which develops its major organs within 24 hours of fertilisation, makes the creature a popular object for study among genetic scientists, and there are about 500 groups in the world studying it now, said Dr Peng.

He added that the first set of zebrafish genetic markers was isolated by the University of Washington a few years ago.

The institute's 15,000 is only the second such discovery, he said.

Currently, the institute's team is working on a 'gene chip' with the marker information.

So a scientist trying to find out which genes are the most active when the fish develops from a newly fertilised egg, would run samples he has taken at different stages of the embryo's development through this chip for the answer.

Running samples from the fish's different development stages can offer a picture of which genes are turned on to do what, for example, when a heart develops.

Dr Peng said: 'It's just the beginning. There is much more research to be done.

'The markers are a mere tool, but one that I hope can contribute to our understanding of diseases.'