Cyclic oscillations in melanization within Hystrix porcupine quills.

This article investigates cyclic oscillations in melanin pigmentation within the quills of the Old World porcupine species Hystrix africaeaustralis. Through chemical analyses, including spectrophotometry and high-performance liquid chromatography (HPLC), the study demonstrates that the quills exhibit multiple alternating bands of eumelanin-rich dark brown and weakly pigmented (pheomelanin-dominant) light bands, indicating temporal regulation of melanogenesis during quill growth. The findings reveal that these pigmentation cycles are more complex than the single pheomelanin banding seen in agouti mice and are comparable to cyclic melanization patterns previously observed in certain primates. The study also notes the presence of rare all-white quills, suggesting occasional absence of pigmentation, and highlights that such oscillatory pigmentation patterns are not unique to mammals, as similar banding occurs in the spines of some sea urchins.