Isolation and Identification of Meiosis Inducing Substance in Starfish Asterias amurensis

Abstract

INVESTIGATIONS of the mechanism of starfish spawning induced by injection of a water extract of radial nerves have shown that an active polypeptide acts on the ovary and induces the production of a second substance which is, in the true sense, a meiosis inducing factor as well as a spawning inducing factor^1–7. The neural substance has therefore been renamed gonad stimulating substance (GSS), and the second substance, produced in the ovary, is meiosis inducing substance (MIS)^5,7. Isolated ovarian fragments immersed in seawater containing MIS discharge their eggs^4,5,7, while isolated oocytes with germinal vesicles treated with MIS mature^4–7. The production of MIS by GSS has been demonstrated in isolated ovarian fragments of seven species of starfish, and it seems to be non-species specific among starfishes⁷. MIS is heat stable (100° C, 30 min) and is not a peptide^5,6.