Data from: Developmental mechanisms of stripe patterns in rodents

Mammalian colour patterns are among the most recognizable characteristics found in nature and can have a profound impact on fitness. However, little is known about the mechanisms underlying the formation and subsequent evolution of these patterns. Here we show that, in the African striped mouse (Rhabdomys pumilio), periodic dorsal stripes result from underlying differences in melanocyte maturation, which give rise to spatial variation in hair colour. We identify the transcription factor ALX3 as a regulator of this process. In embryonic dorsal skin, patterned expression of Alx3 precedes pigment stripes and acts to directly repress Mitf, a master regulator of melanocyte differentiation, thereby giving rise to light-coloured hair. Moreover, Alx3 is upregulated in the light stripes of chipmunks, which have independently evolved a similar dorsal pattern. Our results show a previously undescribed mechanism for modulating spatial variation in hair colour and provide insights into how phenotypic novelty evolves.

哺乳动物体色图案是自然界中最易识别的特征之一，且对生存适合度具有深远影响。然而，学界对这类图案形成及后续演化的潜在机制仍知之甚少。本研究显示，在非洲条纹鼠（Rhabdomys pumilio）中，周期性背部条纹源于黑素细胞成熟程度的内在差异，该差异造就了毛发颜色的空间分布变异。我们鉴定出转录因子ALX3是这一过程的调控因子。在胚胎背部皮肤中，Alx3的模式化表达先于色素条纹出现，并可直接抑制黑素细胞分化的核心调控因子小眼畸形相关转录因子（Mitf），进而形成浅色毛发。此外，在独立演化出类似背部条纹图案的花栗鼠的浅色条纹区域中，Alx3的表达同样被上调。本研究揭示了一种此前未被报道的调控毛发颜色空间分布变异的机制，并为表型新特征的演化方式提供了新见解。