Abstract
Increased K+ concentration in seawater induces metamorphosis in the ascidian Herdmania momus. Larvae cultivated at 24°C exhibit highest rates of metamorphosis when treated with 40 mM KCl-elevated seawater at 21°C. At 24°C, H. momus larvae develop competence to respond to KCl-seawater and initiate metamorphosis approximately 3 h after hatching. Larval trunks and tails separated from the anterior papillae region, but maintained in a common tunic at a distance of greater than 60 μm, do not undergo metamorphosis when treated with KCl-seawater; normal muscle degradation does not occur in separated tails while ampullae develop from papillae-containing anterior fragments. Normal programmed degradation of myofibrils occurs when posterior fragments are fused to papillae-containing anterior fragments. These data indicate that H. momus settlement and metamorphosis only occurs when larvae have attained competence, and suggest that an anterior signalling centre is stimulated to release a factor that induces metamorphosis.
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Received: 15 May 1996 / Accepted: 19 September 1996
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Degnan, B., Souter, D., Degnan, S. et al. Induction of metamorphosis with potassium ions requires development of competence and an anterior signalling centre in the ascidian Herdmania momus . Dev Gene Evol 206, 370–376 (1997). https://doi.org/10.1007/s004270050066
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DOI: https://doi.org/10.1007/s004270050066