The mechanisms underlying the development of stripes in some mice and chipmunks are described in a paper published online this week in Nature. The study reveals a common mechanism for patterning in rodents and may yield new insights into the evolution of unique physical traits in other animals.
The formation of distinctive spots and stripes in mammals is not well understood. Hopi Hoekstra and colleagues examined skin development in African striped mice, which have a pattern of a set of two dark-light-dark stripes on their backs. They find that the mechanisms that give rise to the stripes begin during the embryonic stage of development. Specifically, expression of the gene Alx3 in the skin at this stage appears in the region where the dark stripes will ultimately form later in development. The authors determine that Alx3 also suppresses a regulator of pigment-producing cells, thereby creating the light-coloured stripes.Finally, they find that similar mechanisms generate patterns in Eastern chipmunks, which have a similarly striped back. The Eastern chipmunk diverged from the rodent family that includes most mice and rats about 70 million years ago, so this finding suggests that these may be common developmental mechanisms that evolved independently in multiple mammalian species.