Study shows how the zebrafish gets ...(egulating the migration of neurones in t...)

When researchers looked where the molecule was found, they could see that it appeared to line up in the same pattern as a third stripe in the wild-type zebrafish, and around the collar in choker mutants.

The correlation of Sdf expression and melanophore pattern in wild-type and choker mutants embryos was so striking, it immediately suggested that Sdf plays a key role in dictating the pattern of at least this one stripe in zebrafish, said Dr Kelsh.

To test the theory, researchers positioned a bead soaked in human Sdf onto the skin of zebrafish embryo. Even in the choker mutant, this bead attracted the melanophores to where it was implanted.

The researchers also used a technique known as protein knockdown to reduce the amount of Sdf produced in the embryo, and were able to partially remove the third stripe in wild types and to reduce colouring in the neck of the choker mutant.

Sdf is really important, not just for pigmentation but also the development of neurons and germ cells, said Dr Kelsh.

The other three stripes must have some other mechanism controlling their development. We are still looking into how these other three stripes might form.

Pigment pattern formation is a classic problem in developmental biology and whilst there have been lots of mathematical theories on how the fish make different patterns, the underlying genetics have been unclear.

Similarities between animals mean that we can take what we learn about the development of these simple models, and begin applying them to more complex systems, such as humans.

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