INHIBITION OF SEROTONIN-INDUCED OOCYTE MATURATION BY A SPISULA FACTOR

A factor that blocks serotonin (5‐hydroxytryptamine, 5‐HT)‐induced maturation of Spisula oocytes was purified from Spisula oocytes by ultrafiltration through a PM‐10 membrane, charcoal adsorption, and reversed‐phase HPLC on a Partisil ODS‐3 column, The oocyte factor is a heat‐stable, non‐proteinaceous compound with an estimated Mr of less than 1,000 Da. It blocked 5‐HT‐induced maturation of Spisula ooctyes at concentrations ranging from 10 to 100 μg/ml. It did not influence KCl‐ or potassium‐ glutamate‐induced maturation of Spisula oocytes or the maturation of mouse, Chaetopterus, Xenopus, or Asterias oocytes. The oocyte substance may function as a modulator of 5‐HT action and/or be the endogenous meiotic arresting factor in Spisula oocytes. At concentrations exceeding 100 μl/ml, the oocyte factor induced formation of blebs and cytoplasmic droplets. Copyright © 1990 Wiley‐Liss, Inc., A Wiley Company