Zebra fish are widely used in medical research and the study of diseases. Do you know why?

Zebra fish are vertebrates and have a backbone like humans. This means that they are more closely related to humans, than the commonly used invertebrate models.

The fish is named for its five uniform horizontal blue stripes on the sides of the body. Males are torpedo-shaped and have gold stripes between the blue stripes. Females have silver stripes in between the blue stripes.

The zebra fish grows to 2.5 inches and lives for about 5 years. It produces 300 to 500 eggs per spawning. Zebra fish are similar to humans in many biological traits. These include genes, developmental processes, anatomy, physiology and behavior.

Zebra fish are easy to breed, maintain, manipulate and observe in the lab. They do well in several environments. They are small in size and can be kept together in large numbers in a small tank.

Breeding and getting eggs from the zebra fish is relatively easy. Their eggs are produced regularly in large numbers. They are fertilized externally. Their embryos develop rapidly and remain transparent throughout their development.

Their embryos are also smaller in size than many other vertebrate embryos and contain less numbers of cells. So it is easier to trace the development of individual cells.

Females lay large number of eggs. For genetic analysis we need to look at many different embryos at many different stages to understand a given mutation.

These embryos develop outside the motherís body. In contrast, mouse embryos develop inside the mother, and we have to kill the mother to get at them. This would have to be done at each stage of development we want to look at. Each time the embryos as well as the mother will have to die.

But the Zebra fish embryos are transparent like a glass. We can watch the development as it happens in living embryos. We can see the different internal organs, such as the brain, heart, blood, muscles, etc.

In addition, we can monitor the behavior of single cells in live embryos and watch the cells divide. Using dyes, we can trace the formation of the complete organism. It is not possible to achieve this resolution with other systems.

The embryos grow rapidly. They grow from a single cell to a tiny fish within 24 hours. In comparison, mice need 21 days to develop.

We can physically transplant single cells or groups of cells into the host embryos to analyze the behavior of cells at different stages. This can give us a lot of information about how certain gene products act.

In addition, fertilization of the egg can be manipulated so that the embryo contains only itís motherís genes. This allows scientists to study recessive mutations, since the characteristics are inherited from only one parent-the mother.

There is a large community of researchers currently working on the zebra fish.Their findings will surely help us fight diseases in a much better way in the future.

Visalakshi Ramani