Gadusol in epidermal mucus protects larval zebrafish from UVB-induced DNA damage

Zygotic gadusol synthesis in developing zebrafish skin is required to maintain UVB defense throughout larval development, preventing UVB-induced DNA damage and death.

• Why it matters: Maternal gadusol protects embryos, but how UVB protection persists as maternal stores deplete during larval growth was unclear.
• What they did: The study tested gadusol synthesis and epidermal mucus contributions, showing juvenile fish rely solely on zygotic gadusol for UVB protection, while melanin contributes more modestly.
• The result: Gadusol in the epidermal mucus layer intercepts UVB before it reaches underlying cells; depleting epidermal mucocytes increases UVB-induced DNA damage and activates a DNA damage response.