Tentacles excised from syphistoma polyps of Aurelia aurita undergo rapid regeneration to form whole polyps following exposure to an excess or absence of specific ions. It has been shown that a 12-18 h exposure of isolated tentacles to 58 mM excess of Cs+ results in a rapid firing of nematocysts, followed by an accelerated, synchronous polyp morphogenesis. Absence of Mgt2+ from the culture solution for 4-24 h also led to an accelerated, synchronous polyp regeneration. In either experimental set-up, incubation in 5-10 mM hydroxyurea effectively halted regeneration. Exposure to an excess of Li+ (50-200 mm) or K+ (10-50 mM) caused no firing of nematocysts and a percentage of polyp regeneration only slightly higher than control tentacles. Use of the K+ channel blocker tetraethylammonium (TEA; 100-300 mM) lead to similar levels of regeneration. A Ca2+ or K+-reduced artificial culture solution did not enhance regeneration. Ouabain (1 mM) dampened the Cs+ induced acceleration of polyp morphogenesis, and when given without Cs+, elicited a control level response.
Keywords: Aurelia; Ions; Morphogenesis; Polyp; Regeneration.