Proximal to distal gradient of luminescence in the arm of Amphiura filiformis (Echinodermata-Ophiuroidea)

Bioluminescence is a widespread phenomenon. Among benthic phyla, echinoderms contain some luminous representatives. The emission of visible light originates from a biochemical reaction where chemical energy is transformed into luminous energy. Two bioluminescent systems exist to date: the luciferin- luciferase and the photoprotein one. We here report for the first time the presence of a luciferin-luciferase system in Amphiura filiformis. New assay methods have been developed to detect luciferin and luciferase contents in A. filiformis tissues. This work shows that luciferin/luciferase contents increase from arm base to the arm tip; this increase parallels the observed raise of the light intensity induced by potassium chloride (KCl) depolarisation of isolated arm. This new approach will provide a useful tool to study functional recovery of luminous capabilities during regeneration in Amphiura filiformis