Cholera toxin and thyrotropine can replace natural inducers required for the metamorphosis of larvae and buds of the scyphozoanCassiopea andromeda

Abstract

The scyphozoan medusaCassiopea andromeda forms free swimming planulae and buds that metamorphose into tentacle bearing sedentary polyps. About 30% of the planulae and 7% of the buds undergo such metamorphosis within 30 days in sterile natural seawater from the Red Sea. In sterile artificial sea water devoid of any organic substances, normal metamorphosis does not take place. This indicates that both the planulae and the buds require organic morphogenetic inducers present in the sea to settle and metamorphose. The addition of cholera toxin or thyrotropin to preparations of sterile artificial sea water, induced normal metamorphosis. These inducers enhanced the rate of metamorphosis and up to 100% of the planulae and buds formed polyps within 2–18 days. We conclude that our preparations of cholera toxin and thyrotropin mimic the action of natural inducers.