墨西哥盲眼洞穴鱼如何揭示生物钟的秘密
Deep inside the pitch-black caves of northeastern Mexico’s Sierra de El Abra, a small, ghostly fish has learned to live without sunlight. The Mexican tetra, or Astyanax mexicanus, exists in two forms: a silvery surface dweller with functional eyes and a pale, blind cave variant that lost its sight over thousands of generations. What has captivated biologists is not just the loss of vision but how the cavefish fundamentally rewired its internal clock—a discovery that is reshaping our understanding of circadian rhythms.
Circadian clocks are the roughly 24-hour cycles that govern sleep, metabolism, and hormone release in nearly all organisms. For most animals, light is the master cue that keeps these clocks in sync. Yet the blind cavefish thrives in eternal darkness, seemingly without a functioning light-driven timer. When researchers from Mexico’s National Autonomous University first sequenced the fish’s clock genes, they found that the molecular machinery was intact; it had simply become uncoupled from the light-dark cycle that dominates life on the surface.
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