Scientists have discovered how the zebrafish (Danio rerio) develops one of its four stripes.
Their findings add to the growing list of tasks carried out by an important molecule that is involved in the arrangement of everything from nerve cells to reproductive cells in the developing embryo.
The research focused on a particular zebrafish mutant known as choker, which is distinctive because one of the four stripes running down its side is missing, and it has a dark collar around its neck instead.
Dark spots and stripes in fish, amphibians and reptiles are usually caused by a type of cell, known as a melanophore, which contains high quantities of the pigment melanin.
Using time-lapse photography, the team put together movies showing how the melanophores migrate in developing embryos of both the wild-type (naturally occurring) zebrafish and the choker mutant.
At first, cells migrate through the neck region in both wild-type and choker mutant fish to generate two stripes. Then, whilst cell migration ceases in the neck region of the wild-type embryo, melanophores in the choker mutant exit from the two stripes and busily cluster around the collar region of the developing fish.
It is as though someone has put up keep off the grass signs in the wild-type zebrafish to keep the melanophores in separate paths (stripes), said Dr Robert Kelsh from the University of Bath who led the study which was published in the journal Development.
The melanophores stay on the footpath of the developing stripe in a very orderly fashion, but in choker its as though these signs have been knocked down, and the pigment cells run all over the grass between the footpaths.
The breakthrough in understanding how this happens came with the discovery that a molecule, known as Sdf, appears to have some role in encouraging melanophore cell migration.
Sdf is a known cell migration guidance molecule, with roles including r
|Contact: Andrew McLaughlin|
University of Bath